Merge local and federated similarity results

ARCHITECTURE.md

@@ -123,6 +123,22 @@ The DHT is the distributed index. Nodes publish compact searchable
 descriptions of their local library and query the network without contacting a
 central search service.
 
+Similarity discovery uses a separate schema-independent DHT overlay. A node
+derives a deterministic 256-bit routing signature from every local embedding,
+groups them into fixed two-level LSH buckets, and publishes compact summaries
+containing only fine-bucket representatives, its peer identity, and the ticket
+needed to dial a previously unknown owner. The owner signs every summary with
+its existing transport key, so storage peers can relay and cache it but cannot
+impersonate or modify it. Summaries expire with the ordinary library-record TTL
+and are replaceable federation cache, never local library authority.
+
+A similarity search first performs bounded multi-probe LSH lookups to rank
+likely owners, then sends the existing normalized-vector request directly to
+at most 16 peers initially and 48 on fallback. Known peers remain a rollout
+fallback. The model, preprocessing, durable embeddings, exact cosine search,
+and consent policy remain client-owned; `music-dht` owns only compatible
+routing math, signed records, replication, and wire bounds.
+
 Once a peer is known, communication moves to direct P2P streams provided by
 iroh through `music-dht`. Furumi defines separate application protocols for
 catalog requests, audio transfer, and trusted-device synchronization. This
@@ -282,6 +298,31 @@ intended role: transforming current audio features into drawing commands. It
 is not a plugin mechanism for accessing the library, network, or player
 controls.
 
+## Music-similarity indexing
+
+Similarity search is an optional local capability and is disabled by default.
+When enabled, a background pipeline downloads a selected ONNX model, verifies
+its pinned SHA-256 digest, decodes durable local tracks, and stores normalized
+embeddings in the library SQLite database. Embeddings are keyed by an exact
+fingerprint of the model artifact and preprocessing profile. Old profile rows
+remain available while a new profile is calculated, and the in-memory exact
+cosine index switches only after the replacement profile is usable.
+
+The SQLite rows are the canonical derived store. The in-memory index can be
+discarded and rebuilt, and neither is required for import, browsing, or
+playback. Remote/cache-only tracks are never scheduled for local embedding.
+
+Federated similarity uses a separate versioned direct-stream protocol. With
+explicit privacy consent, the requester sends only a normalized embedding and
+its profile fingerprint to a bounded set of known peers. It does not publish
+queries to the DHT. Each peer searches its own active local index and returns a
+bounded metadata result with a compact embedding SimHash. The requester uses
+that signature to suppress near-duplicate recordings across peers without
+receiving every result vector. Fan-out, concurrency, message sizes, and
+timeouts are bounded; incompatible profiles are rejected. This direct
+peer-selection layer can later be replaced by DHT routing without changing
+local storage or ranking.
+
 ## Persistence boundaries
 
 Furumi stores different kinds of state according to their lifetime:
@@ -290,6 +331,7 @@ Furumi stores different kinds of state according to their lifetime:
 | --- | --- | --- |
 | Library, playlists, likes, history | SQLite | Durable local source of truth |
 | Device operation log and replicas | SQLite | Offline synchronization |
+| Versioned track embeddings | SQLite | Durable, locally rebuildable similarity data |
 | Federation catalog cache | SQLite/cache | Faster network browsing |
 | Audio and artwork cache | Filesystem cache | Reusable fetched data |
 | Settings, keymap, identity | Platform config/data dirs | Node configuration |
@@ -321,6 +363,8 @@ The source tree follows the architectural responsibilities:
 
 - `library/` owns the local catalog and import pipeline;
 - `player/` owns audio playback and analysis;
+- `similarity.rs` owns model acquisition, preprocessing, background indexing,
+  and the replaceable exact in-memory index;
 - `federation/` owns DHT-facing search, peer catalogs, and audio exchange;
 - `devices.rs` owns trusted-device replication and playback coordination;
 - `app/` owns state transitions and runtime orchestration;

CHANGELOG.md

@@ -0,0 +1,78 @@
+# Changelog
+
+All notable changes to Furumi are documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+
+- Optional offline music-similarity search for local tracks, backed by
+  versioned SQLite embeddings and a replaceable exact in-memory cosine index.
+- Automatic SHA-256-verified download and local inference for the first ONNX
+  embedding model, with retained model/profile generations and background
+  backfilling of existing library tracks.
+- Similarity settings for enablement, model/profile information, numeric worker
+  count, derived-data cleanup, processing progress, and federation privacy
+  consent.
+- Track-seeded similarity search from the track-information popup, including
+  bounded federated queries to compatible known peers.
+- The `furumi-fd/similarity/1` protocol in the visible protocol-version status.
+- Decentralized `similarity_dht` routing with signed anonymous two-level LSH
+  summaries, multi-probe lookup beyond the locally known peer set, and known-
+  peer fallback during gradual network upgrades.
+
+### Changed
+
+- Similarity wire types, bounds, validation, and stream framing now come from
+  the shared `music-dht 0.4.0` API so native, web, and future clients can
+  interoperate without sharing an embedding implementation.
+- Existing SQLite embeddings are backfilled once with compact 256-bit routing
+  signatures; new embeddings store them immediately without changing exact
+  local cosine search.
+- A similarity result page keeps the source track first as query context while
+  excluding it from the actual nearest-neighbor ranking, labels the mode as
+  `Search similar to`, and suppresses near-identical embeddings across releases
+  and federated peer responses.
+- Preprocessing profiles now open a read-only details window describing their
+  audio selection, resampling, spectrogram, patching, and aggregation contract.
+
+### Fixed
+
+- Current-track information (`Shift+I`) now uses the enriched queue entry, so
+  it shows the same complete metadata and similarity action as `I` on that
+  track in the queue.
+
+## [0.2.5] - 2026-08-02
+
+### Added
+
+- Command history navigation with the Up and Down arrow keys.
+- A copy-friendly plain terminal view for connection tickets, device and Jam
+  invites, and track-sharing links.
+- A configurable permanent music directory with write validation and an
+  optional safe migration of existing Furumi-managed files.
+- Queue reordering for one track or a `Shift+V` selection with `Alt+K` and
+  `Alt+J`.
+- Reproducible Nix/devenv tooling with Rust 1.97 and ALSA development files.
+
+### Changed
+
+- Sequential `a` actions now build one ordered play-next block instead of
+  reversing independently inserted tracks.
+- Federated artist images and release covers are stored beside permanent music
+  in an `Artist/Release` directory tree.
+
+### Fixed
+
+- Running a development build next to another Furumi instance no longer lets
+  an MPRIS name collision disable terminal raw mode and freeze keyboard input.
+- `nix develop` now keeps devenv state outside the read-only Nix store and
+  isolates Rust 1.97 build artifacts from other toolchains.
+- Music-directory validation and migration now reject overlapping changes,
+  resolve canonical paths, and produce Windows-portable managed filenames.
+
+[Unreleased]: https://gt.hexor.cy/ab/furumi_tui/compare/v0.2.5...HEAD
+[0.2.5]: https://gt.hexor.cy/ab/furumi_tui/compare/v0.2.4...v0.2.5

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "furumi_tui"
-version = "0.2.4"
+version = "0.2.6"
 edition = "2024"
 rust-version = "1.97"
 description = "A federated P2P player for personal music libraries"
@@ -21,19 +21,23 @@ image = { version = "0.25.10", default-features = false, features = ["jpeg", "pn
 lofty = "0.22"
 # P2P federation: library index in a shared DHT + audio streaming between
 # peers (same protocol as furumi-fd).
-music-dht = "0.3"
+music-dht = "0.4.0"
 ratatui = "0.30.1"
+reqwest = { version = "0.12.28", default-features = false, features = ["rustls-tls", "stream"] }
 rhai = { version = "1", features = ["sync"] }
 rodio = { version = "0.22.2", default-features = false, features = ["playback", "mp3", "flac", "vorbis", "wav", "symphonia-aac", "symphonia-isomp4", "symphonia-alac"] }
+rustfft = "6.4.1"
 rusqlite = { version = "0.32", features = ["bundled", "functions"] }
 serde = { version = "1.0.228", features = ["derive"] }
 serde_json = "1.0.150"
+sha2 = "0.10.9"
 souvlaki = { version = "0.8.3", default-features = false, features = ["use_zbus"] }
 thiserror = "2.0.18"
 tokio = { version = "1.52.3", features = ["rt-multi-thread", "macros", "sync", "time", "fs", "io-util"] }
 toml = "1.1.2"
 tracing = "0.1.44"
 tracing-subscriber = { version = "0.3.23", features = ["env-filter"] }
+tract-onnx = "0.23.4"
 unicode-width = "0.2.2"
 
 [patch.crates-io]

README.md

@@ -69,6 +69,16 @@ library management are included. Visualizations are runtime-loadable Rhai
 scripts executed in a resource-limited sandbox, so they can be added or edited
 without rebuilding the player.
 
+Optional similarity search calculates versioned embeddings for local tracks
+in the background and keeps them in SQLite. It works offline; after a separate
+privacy consent it can also ask a bounded set of federation peers for matches.
+Compatible peers are selected through signed, anonymous LSH summaries in a
+decentralized DHT; no central recommendation index or shared calibration file
+is required.
+The first selectable model is downloaded on demand and is licensed separately
+by MTG under CC BY-NC-SA 4.0 (a proprietary license is also available from
+MTG); Furumi itself remains WTFPL.
+
 ## Install
 
 ### macOS
@@ -144,6 +154,7 @@ Furumi is a Rust application built with:
 - `ratatui` and `crossterm` for the cross-platform TUI;
 - `rodio` for local audio playback;
 - SQLite for the personal library and synchronization state;
+- tract ONNX inference for optional local music embeddings;
 - a dedicated DHT for decentralized discovery;
 - iroh-based P2P streams for client-to-client communication;
 - an offline-tolerant operation log for trusted-device synchronization;

devenv.nix

@@ -0,0 +1,40 @@
+{ config, lib, pkgs, ... }:
+
+let
+  sourceRoot = builtins.toString ./.;
+  sourceKey = builtins.substring 0 12 (builtins.hashString "sha256" sourceRoot);
+  transientDotfile = "/tmp/furumi-tui-devenv-${sourceKey}";
+  rustToolchain = builtins.fromTOML (builtins.readFile ./rust-toolchain.toml);
+  rustVersion = rustToolchain.toolchain.channel;
+in
+{
+  # Pure flakes only expose their read-only store source. Keep devenv's own
+  # task/profile state writable, then restore the real checkout path in-shell.
+  devenv.root = sourceRoot;
+  devenv.dotfile = transientDotfile;
+  devenv.state = "${transientDotfile}/state";
+
+  languages.rust = {
+    enable = true;
+    toolchainFile = ./rust-toolchain.toml;
+  };
+
+  packages = [
+    pkgs.pkg-config
+  ] ++ pkgs.lib.optionals pkgs.stdenv.isLinux [
+    pkgs.alsa-lib
+  ];
+
+  env.RUST_BACKTRACE = "1";
+
+  enterShell = lib.mkAfter ''
+    export DEVENV_ROOT="$PWD"
+    # Keep Nix builds separate from artifacts produced by rustup or another
+    # devenv generation. Cargo metadata is not compatible across compilers.
+    export CARGO_TARGET_DIR="$PWD/target/devenv-rust-${rustVersion}"
+    export PATH="${config.languages.rust.toolchainPackage}/bin:$PATH"
+    export RUSTC="${config.languages.rust.toolchainPackage}/bin/rustc"
+    export RUSTDOC="${config.languages.rust.toolchainPackage}/bin/rustdoc"
+    hash -r
+  '';
+}

flake.lock

@@ -0,0 +1,399 @@
+{
+  "nodes": {
+    "cachix": {
+      "inputs": {
+        "devenv": [
+          "devenv"
+        ],
+        "flake-compat": [
+          "devenv",
+          "flake-compat"
+        ],
+        "git-hooks": [
+          "devenv",
+          "git-hooks"
+        ],
+        "nixpkgs": "nixpkgs"
+      },
+      "locked": {
+        "lastModified": 1777487137,
+        "narHash": "sha256-TuvKVBX60mqyMT6OB5JqVEh1YIWtFMR/igLCaCdC9tw=",
+        "owner": "cachix",
+        "repo": "cachix",
+        "rev": "a66a440c321d35f7193472c317f42a55ccd1cb93",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "ref": "latest",
+        "repo": "cachix",
+        "type": "github"
+      }
+    },
+    "crate2nix": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1772186516,
+        "narHash": "sha256-8s28pzmQ6TOIUzznwFibtW1CMieMUl1rYJIxoQYor58=",
+        "owner": "rossng",
+        "repo": "crate2nix",
+        "rev": "ba5dd398e31ee422fbe021767eb83b0650303a6e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "rossng",
+        "repo": "crate2nix",
+        "rev": "ba5dd398e31ee422fbe021767eb83b0650303a6e",
+        "type": "github"
+      }
+    },
+    "devenv": {
+      "inputs": {
+        "cachix": "cachix",
+        "crate2nix": "crate2nix",
+        "flake-compat": "flake-compat",
+        "flake-parts": "flake-parts",
+        "ghostty": "ghostty",
+        "git-hooks": "git-hooks",
+        "nix": "nix",
+        "nixd": "nixd",
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "rust-overlay": "rust-overlay"
+      },
+      "locked": {
+        "lastModified": 1785616853,
+        "narHash": "sha256-WKA53CfbSwXh/QuGHc3gsWoLNHYaKw4xgvkc9ceRgUA=",
+        "owner": "cachix",
+        "repo": "devenv",
+        "rev": "a3feed9ca96c66548496e8af2804d2a3a045d22e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "devenv",
+        "type": "github"
+      }
+    },
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1767039857,
+        "narHash": "sha256-vNpUSpF5Nuw8xvDLj2KCwwksIbjua2LZCqhV1LNRDns=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "5edf11c44bc78a0d334f6334cdaf7d60d732daab",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-parts": {
+      "inputs": {
+        "nixpkgs-lib": [
+          "devenv",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1778716662,
+        "narHash": "sha256-m1Yf0wZ8j1OHjTc2UwHwyQRSnNeSgLJOd7q5Y45hzi4=",
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "rev": "f7c1a2d347e4c52d5fb8d10cb4d94b5884e546fb",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "type": "github"
+      }
+    },
+    "flake-parts_2": {
+      "inputs": {
+        "nixpkgs-lib": "nixpkgs-lib"
+      },
+      "locked": {
+        "lastModified": 1782949081,
+        "narHash": "sha256-vp6Y/Grm98ESt6ceOkWiHWyZRDV3J1RID4w+6NWK9yA=",
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "rev": "17c9d6cdfc60c64f4ee8d306f9bc0b4ccb51481e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "type": "github"
+      }
+    },
+    "ghostty": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1784602798,
+        "narHash": "sha256-298x90knBUWX5GHGXh2SKsAKvStjU2ri9UgOGoF79/8=",
+        "owner": "ghostty-org",
+        "repo": "ghostty",
+        "rev": "88b4cd047fa627cdca6781bc7e7dc8b75a2cecb9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ghostty-org",
+        "repo": "ghostty",
+        "type": "github"
+      }
+    },
+    "git-hooks": {
+      "inputs": {
+        "flake-compat": [
+          "devenv",
+          "flake-compat"
+        ],
+        "nixpkgs": [
+          "devenv",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1782908218,
+        "narHash": "sha256-wLMOrPgVyeF3XmP+qfYcLqnVdTxikdcSvbIY7rA9jTA=",
+        "owner": "cachix",
+        "repo": "git-hooks.nix",
+        "rev": "9f7e99119ece7705299595299f3b031f39356de1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "git-hooks.nix",
+        "type": "github"
+      }
+    },
+    "mk-shell-bin": {
+      "locked": {
+        "lastModified": 1677004959,
+        "narHash": "sha256-/uEkr1UkJrh11vD02aqufCxtbF5YnhRTIKlx5kyvf+I=",
+        "owner": "rrbutani",
+        "repo": "nix-mk-shell-bin",
+        "rev": "ff5d8bd4d68a347be5042e2f16caee391cd75887",
+        "type": "github"
+      },
+      "original": {
+        "owner": "rrbutani",
+        "repo": "nix-mk-shell-bin",
+        "type": "github"
+      }
+    },
+    "nix": {
+      "inputs": {
+        "flake-compat": [
+          "devenv",
+          "flake-compat"
+        ],
+        "flake-parts": [
+          "devenv",
+          "flake-parts"
+        ],
+        "git-hooks-nix": [
+          "devenv",
+          "git-hooks"
+        ],
+        "nixpkgs": [
+          "devenv",
+          "nixpkgs"
+        ],
+        "nixpkgs-23-11": [
+          "devenv"
+        ],
+        "nixpkgs-regression": [
+          "devenv"
+        ]
+      },
+      "locked": {
+        "lastModified": 1785349663,
+        "narHash": "sha256-JSD8lPe5kalvPKx5X+inX8ZZdGLeXkAbd3Jiv7UDf+I=",
+        "owner": "cachix",
+        "repo": "nix",
+        "rev": "f33db89fd6db6edc337d93212f6628ab6d25f407",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "ref": "devenv-2.34",
+        "repo": "nix",
+        "type": "github"
+      }
+    },
+    "nix2container": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1775487831,
+        "narHash": "sha256-2lguQpLPQaxpQCJjXhmEEAfabwsAhkP29Z7fgLzHARA=",
+        "owner": "nlewo",
+        "repo": "nix2container",
+        "rev": "76be9608a7f4d6c985d28b0e7be903ae2547df3e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nlewo",
+        "repo": "nix2container",
+        "type": "github"
+      }
+    },
+    "nixd": {
+      "inputs": {
+        "flake-parts": [
+          "devenv",
+          "flake-parts"
+        ],
+        "nixpkgs": [
+          "devenv",
+          "nixpkgs"
+        ],
+        "treefmt-nix": "treefmt-nix"
+      },
+      "locked": {
+        "lastModified": 1783935112,
+        "narHash": "sha256-IAQ14nteIKXAz4cd75UcZrsHGEVJ7QNrkUwX9rmeZ/Y=",
+        "owner": "nix-community",
+        "repo": "nixd",
+        "rev": "a64cd33e53b316b6b092ea0a966640cd2309bf3d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "nixd",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1772624091,
+        "narHash": "sha256-QKyJ0QGWBn6r0invrMAK8dmJoBYWoOWy7lN+UHzW1jc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "80bdc1e5ce51f56b19791b52b2901187931f5353",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-lib": {
+      "locked": {
+        "lastModified": 1782614948,
+        "narHash": "sha256-ePjCwr1sNm9NYUqywL7QfK3JnlS015msC+eBu2zKlp8=",
+        "owner": "nix-community",
+        "repo": "nixpkgs.lib",
+        "rev": "db3f255737b94216eb71cce308e2912cf6bc2d7c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "nixpkgs.lib",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1785571196,
+        "narHash": "sha256-KoTsyMQqnXQZq8deCEnu4QkyldkwH/bpMMhUcfMdGIw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "148bab9c1c3c53136ecb44a6ea356a0ed5b39b06",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "devenv": "devenv",
+        "flake-parts": "flake-parts_2",
+        "mk-shell-bin": "mk-shell-bin",
+        "nix2container": "nix2container",
+        "nixpkgs": "nixpkgs_2",
+        "rust-overlay": "rust-overlay_2"
+      }
+    },
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": [
+          "devenv",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1782875958,
+        "narHash": "sha256-5eqDcnBjb1424HRQdnhuhNOBZguq1Z2tqSa2OMF/m2c=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "13139aefa973f3d96c60c0fbab801de058ae25ca",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    },
+    "rust-overlay_2": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1785562362,
+        "narHash": "sha256-J15aBa3d6B1SUUAQydQ06wFjPzrrcVceb6jkdfwfGls=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "5f29c219a7655519f8a9f8c6968064b82c17cc93",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "devenv",
+          "nixd",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1780220602,
+        "narHash": "sha256-eynAfOmbmxJnkp7YewvCEbShNnnYJ9gLLqkzsYtBPeM=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "db947814a175b7ca6ded66e21383d938df01c227",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,33 @@
+{
+  description = "Furumi TUI development environment";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    devenv.url = "github:cachix/devenv";
+    devenv.inputs.nixpkgs.follows = "nixpkgs";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+    rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
+    nix2container.url = "github:nlewo/nix2container";
+    nix2container.inputs.nixpkgs.follows = "nixpkgs";
+    mk-shell-bin.url = "github:rrbutani/nix-mk-shell-bin";
+  };
+
+  outputs = inputs@{ flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = [
+        "x86_64-linux"
+        "aarch64-linux"
+        "x86_64-darwin"
+        "aarch64-darwin"
+      ];
+
+      imports = [ inputs.devenv.flakeModule ];
+
+      perSystem = { ... }: {
+        devenv.shells.default = {
+          imports = [ ./devenv.nix ];
+        };
+      };
+    };
+}

rust-toolchain.toml

@@ -0,0 +1,4 @@
+[toolchain]
+channel = "1.97.0"
+profile = "minimal"
+components = ["clippy", "rust-src", "rustfmt"]

src/app/action.rs

@@ -38,6 +38,8 @@ pub enum Action {
     OpenCurrentTrackInfo,
     QueueAddNext,
     QueueAddLast,
+    MoveQueueUp,
+    MoveQueueDown,
     /// Download the selected federated track(s) into the local library.
     DownloadSelected,
     RemoveFromQueue,
@@ -107,6 +109,8 @@ impl Action {
             | Action::OpenListenHistory => Category::Playback,
             Action::QueueAddNext
             | Action::QueueAddLast
+            | Action::MoveQueueUp
+            | Action::MoveQueueDown
             | Action::DownloadSelected
             | Action::RemoveFromQueue
             | Action::ClearQueue
@@ -193,6 +197,8 @@ impl Action {
             Action::OpenCurrentTrackInfo => "Current track info".into(),
             Action::QueueAddNext => "Queue: add next".into(),
             Action::QueueAddLast => "Queue: add to end".into(),
+            Action::MoveQueueUp => "Queue: move track/selection up".into(),
+            Action::MoveQueueDown => "Queue: move track/selection down".into(),
             Action::DownloadSelected => "Federation: download to library".into(),
             Action::RemoveFromQueue => "Queue: remove selected".into(),
             Action::ClearQueue => "Queue: clear".into(),

src/app/cmdline.rs

@@ -17,6 +17,16 @@ pub fn handle_key(state: &mut AppState, runtime: &mut Runtime, key: KeyEvent) {
     match key.code {
         KeyCode::Esc => cancel(state),
         KeyCode::Enter => commit(state, runtime),
+        KeyCode::Up => {
+            if state.cmdline.history_previous() {
+                after_change(state, runtime);
+            }
+        }
+        KeyCode::Down => {
+            if state.cmdline.history_next() {
+                after_change(state, runtime);
+            }
+        }
         // Backspace on an empty line closes it, like vim.
         KeyCode::Backspace if state.cmdline.input.is_empty() => cancel(state),
         _ => {
@@ -87,6 +97,11 @@ fn set_view_cursor_zero(state: &mut AppState) {
 /// spawned task only queries if it is still the latest after the debounce,
 /// and the receiver drops responses that arrive out of date.
 pub(super) fn schedule_search(state: &mut AppState, runtime: &Runtime) {
+    state.search.similarity_source = None;
+    state.search.similarity_source_track = None;
+    state.search.similarity_tracks.clear();
+    state.search.similarity_stats = None;
+    state.search.similarity_error = None;
     let seq = runtime.search_seq.fetch_add(1, Ordering::SeqCst) + 1;
     let query = state.search.query.clone();
     if query.is_empty() {
@@ -135,6 +150,53 @@ pub(super) fn schedule_search(state: &mut AppState, runtime: &Runtime) {
     }
 }
 
+pub(super) fn schedule_similarity_search(
+    state: &mut AppState,
+    runtime: &Runtime,
+    track: &crate::library::models::TrackItem,
+) {
+    let seq = runtime.search_seq.fetch_add(1, Ordering::SeqCst) + 1;
+    let artist = track.artist_line();
+    state.search.query = if artist.is_empty() {
+        track.title.clone()
+    } else {
+        format!("{} — {artist}", track.title)
+    };
+    state.search.similarity_source = Some(track.id);
+    state.search.similarity_source_track = Some(track.clone());
+    state.search.similarity_tracks.clear();
+    state.search.similarity_stats = None;
+    state.search.similarity_error = None;
+    state.search.loading = true;
+    state.search.results = None;
+    state.search.fed_tracks.clear();
+    state.search.fed_artists.clear();
+    state.search.fed_loading = false;
+    state.active_tab = crate::app::state::Tab::Global;
+    if let Some(crate::app::state::GlobalView::Search { cursor }) = state.global.stack.last_mut() {
+        *cursor = 0;
+    } else {
+        state
+            .global
+            .stack
+            .push(crate::app::state::GlobalView::Search { cursor: 0 });
+    }
+
+    let similarity = Arc::clone(&runtime.similarity);
+    let tx = runtime.event_tx.clone();
+    let track_id = track.id;
+    tokio::task::spawn_blocking(move || {
+        let result = similarity
+            .search_track(track_id, 49)
+            .map(|(matches, query)| (matches, query));
+        let (result, query) = match result {
+            Ok((results, query)) => (Ok(results), Some(query)),
+            Err(err) => (Err(format!("{err:#}")), None),
+        };
+        let _ = tx.send(AppEvent::SimilaritySearchLoaded { seq, result, query });
+    });
+}
+
 /// Refresh only the local-library half of an already open search.
 ///
 /// Library/device sync notifications can arrive while federated search
@@ -142,6 +204,9 @@ pub(super) fn schedule_search(state: &mut AppState, runtime: &Runtime) {
 /// federation rows and bump the shared sequence, causing valid network
 /// responses to be dropped or flicker away.
 pub(super) fn refresh_local_search(state: &mut AppState, runtime: &Runtime) {
+    if state.search.similarity_source.is_some() {
+        return;
+    }
     let query = state.search.query.clone();
     if query.is_empty() {
         return;
@@ -162,7 +227,9 @@ pub(super) fn refresh_local_search(state: &mut AppState, runtime: &Runtime) {
 /// Enter: close the line. Live commands already took effect (their view
 /// stays open); one-shot commands execute here.
 fn commit(state: &mut AppState, runtime: &mut Runtime) {
+    let remembered = state.cmdline.input.as_str().to_string();
     let parsed = command::parse(&state.cmdline.input);
+    state.cmdline.remember(&remembered);
     close(state);
     match parsed {
         Parsed::Empty => {}
@@ -272,6 +339,7 @@ fn close(state: &mut AppState) {
     state.cmdline.active = false;
     state.cmdline.input.clear();
     state.cmdline.live = false;
+    state.cmdline.begin_history_navigation();
 }
 
 /// Pop the live search view if this command-line session opened it.

src/app/event.rs

@@ -32,6 +32,21 @@ pub enum AppEvent {
         seq: u64,
         result: Result<SearchResults, String>,
     },
+    /// Local similar-track search completed. It uses the same sequence as
+    /// text search so stale pages cannot overwrite a newer request.
+    SimilaritySearchLoaded {
+        seq: u64,
+        result: Result<Vec<crate::similarity::SimilarTrack>, String>,
+        query: Option<crate::similarity::QueryVector>,
+    },
+    /// Federated candidates and diagnostics for a track-seeded search.
+    FedSimilaritySearchLoaded {
+        seq: u64,
+        result: Result<crate::federation::FedSimilaritySearchResults, String>,
+    },
+    SimilarityStatus(crate::similarity::SimilarityStatus),
+    /// `None` is emitted after clearing every stored embedding.
+    SimilarityProfileActivated(Option<String>),
     /// Artwork loaded and decoded for the shared art cache.
     ArtLoaded {
         key: String,
@@ -56,6 +71,8 @@ pub enum AppEvent {
     LocalContentIdsLoaded(Result<Vec<String>, String>),
     /// Counts and storage footprint of the local library/database.
     LocalLibraryStatsLoaded(Result<crate::library::LocalLibraryStats, String>),
+    MusicDirectoryValidated(Result<std::path::PathBuf, String>),
+    MusicDirectoryChanged(Result<crate::library::MusicRelocationStats, String>),
     ListenHistoryLoaded(Result<Vec<crate::library::ListenHistoryEntry>, String>),
     /// One content id became available locally while the UI is open.
     LocalContentAvailable {

src/app/mod.rs

@@ -8,6 +8,7 @@ pub mod state;
 pub mod update;
 
 use std::io;
+use std::io::Write as _;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::sync::Arc;
@@ -40,8 +41,13 @@ pub struct Runtime {
     pub devices: Arc<crate::devices::DeviceSync>,
     pub jam: Arc<crate::jam::JamManager>,
     pub federation: Arc<crate::federation::Federation>,
+    pub similarity: Arc<crate::similarity::Manager>,
     /// When the last Federation-tab status snapshot was requested.
     pub fed_status_at: Option<std::time::Instant>,
+    /// Keeps the last successful local-data snapshot visible while a newer
+    /// one is calculated and collapses bursts of library-change events.
+    pub local_library_stats_refreshing: Arc<std::sync::atomic::AtomicBool>,
+    pub local_library_stats_refresh_requested: Arc<std::sync::atomic::AtomicBool>,
     pub library_network_refresh_at: Option<std::time::Instant>,
     pub library_network_refreshing: Arc<std::sync::atomic::AtomicBool>,
     pub library_network_cursors:
@@ -61,6 +67,8 @@ pub struct Runtime {
     pub art_semaphore: Arc<tokio::sync::Semaphore>,
     /// The terminal screen was externally disturbed and needs a full repaint.
     pub force_redraw: bool,
+    /// The alternate screen is temporarily suspended for copy-friendly text.
+    pub plain_text_mode: bool,
     /// Monotonic sequence for live search; stale responses are dropped.
     pub search_seq: Arc<std::sync::atomic::AtomicU64>,
     pub player: player::Controller,
@@ -98,11 +106,49 @@ fn refresh_local_content_ids(runtime: &Runtime) {
 }
 
 fn refresh_local_library_stats(runtime: &Runtime) {
+    runtime
+        .local_library_stats_refresh_requested
+        .store(true, std::sync::atomic::Ordering::Release);
+    if runtime
+        .local_library_stats_refreshing
+        .swap(true, std::sync::atomic::Ordering::AcqRel)
+    {
+        return;
+    }
     let library = Arc::clone(&runtime.library);
     let tx = runtime.event_tx.clone();
+    let refreshing = Arc::clone(&runtime.local_library_stats_refreshing);
+    let requested = Arc::clone(&runtime.local_library_stats_refresh_requested);
     tokio::task::spawn_blocking(move || {
-        let result = library.local_stats().map_err(err_string);
-        let _ = tx.send(AppEvent::LocalLibraryStatsLoaded(result));
+        loop {
+            requested.store(false, std::sync::atomic::Ordering::Release);
+            let result = library.local_stats().map_err(err_string);
+            let _ = tx.send(AppEvent::LocalLibraryStatsLoaded(result));
+            if requested.load(std::sync::atomic::Ordering::Acquire) {
+                continue;
+            }
+            refreshing.store(false, std::sync::atomic::Ordering::Release);
+            if requested.swap(false, std::sync::atomic::Ordering::AcqRel)
+                && !refreshing.swap(true, std::sync::atomic::Ordering::AcqRel)
+            {
+                continue;
+            }
+            break;
+        }
+    });
+}
+
+pub(super) fn validate_music_directory(state: &mut AppState, runtime: &Runtime, path: PathBuf) {
+    if state.music_dir_changing {
+        state.status_message = Some("music directory change is already running".into());
+        return;
+    }
+    state.music_dir_changing = true;
+    state.status_message = Some("checking music directory write access…".into());
+    let tx = runtime.event_tx.clone();
+    tokio::task::spawn_blocking(move || {
+        let result = Library::validate_music_directory(&path).map_err(err_string);
+        let _ = tx.send(AppEvent::MusicDirectoryValidated(result));
     });
 }
 
@@ -244,6 +290,8 @@ pub async fn run(
     };
     state.player.volume = settings.volume;
     state.global.filters = settings.library;
+    state.music_dir = settings.music_dir.clone();
+    state.similarity.settings = settings.similarity.clone();
     if let Err(err) = state.visualizer.load_library() {
         state.status_message = Some(format!("visualizations disabled: {err:#}"));
     }
@@ -251,11 +299,20 @@ pub async fn run(
     let devices = crate::devices::DeviceSync::new(Arc::clone(&library))?;
     devices.set_event_tx(event_tx.clone());
     let jam = crate::jam::JamManager::new(event_tx.clone());
+    let similarity = crate::similarity::Manager::new(
+        Arc::clone(&library),
+        event_tx.clone(),
+        settings.similarity.clone(),
+    );
+    state.similarity.status = similarity.status();
     let federation = crate::federation::Federation::new(
         Arc::clone(&library),
         Arc::clone(&devices),
         Arc::clone(&jam),
+        Arc::clone(&similarity),
+        settings.music_dir.clone(),
     );
+    state.music_dir = federation.media_dir();
     state.federation.settings = federation.settings();
     state.federation.devices = Some(devices.status());
     if let Ok((device_id, device_name)) = devices.identity_summary() {
@@ -272,7 +329,10 @@ pub async fn run(
         devices,
         jam,
         federation,
+        similarity,
         fed_status_at: None,
+        local_library_stats_refreshing: Arc::new(std::sync::atomic::AtomicBool::new(false)),
+        local_library_stats_refresh_requested: Arc::new(std::sync::atomic::AtomicBool::new(false)),
         library_network_refresh_at: None,
         library_network_refreshing: Arc::new(std::sync::atomic::AtomicBool::new(false)),
         library_network_cursors: Arc::new(std::sync::Mutex::new(std::collections::HashMap::new())),
@@ -288,6 +348,7 @@ pub async fn run(
         fed_streaming: Arc::new(std::sync::Mutex::new(std::collections::HashSet::new())),
         art_semaphore: Arc::new(tokio::sync::Semaphore::new(4)),
         force_redraw: false,
+        plain_text_mode: false,
         search_seq: Arc::new(std::sync::atomic::AtomicU64::new(0)),
         player: player::spawn(move |event| {
             let _ = player_events.send(AppEvent::Player(event));
@@ -298,6 +359,9 @@ pub async fn run(
         status_publisher: crate::status::Publisher::spawn(),
     };
     spawn_content_id_backfill(&runtime);
+    if state.similarity.settings.enabled {
+        runtime.similarity.start();
+    }
 
     {
         let fed = Arc::clone(&runtime.federation);
@@ -318,11 +382,30 @@ pub async fn run(
     visual_tick.set_missed_tick_behavior(MissedTickBehavior::Skip);
 
     loop {
-        if runtime.force_redraw {
-            terminal.clear()?;
-            runtime.force_redraw = false;
+        let plain_text = match state.popup.as_ref() {
+            Some(state::Popup::PlainText { text }) => Some(text.as_str()),
+            _ => None,
+        };
+        match (runtime.plain_text_mode, plain_text) {
+            (false, Some(text)) => {
+                enter_plain_text_mode(text)?;
+                runtime.plain_text_mode = true;
+            }
+            (true, None) => {
+                leave_plain_text_mode()?;
+                runtime.plain_text_mode = false;
+                runtime.force_redraw = true;
+            }
+            _ => {}
+        }
+
+        if !runtime.plain_text_mode {
+            if runtime.force_redraw {
+                terminal.clear()?;
+                runtime.force_redraw = false;
+            }
+            terminal.draw(|frame| ui::draw(frame, &state, &keymap))?;
         }
-        terminal.draw(|frame| ui::draw(frame, &state, &keymap))?;
 
         tokio::select! {
             maybe_event = input.next() => match maybe_event {
@@ -347,6 +430,10 @@ pub async fn run(
         }
 
         if state.should_quit {
+            if runtime.plain_text_mode {
+                leave_plain_text_mode()?;
+                runtime.plain_text_mode = false;
+            }
             state.shutting_down = true;
             terminal.draw(|frame| ui::draw(frame, &state, &keymap))?;
             runtime.federation.shutdown().await;
@@ -356,6 +443,32 @@ pub async fn run(
     }
 }
 
+fn enter_plain_text_mode(text: &str) -> Result<()> {
+    let text: String = text
+        .chars()
+        .filter(|character| !character.is_control())
+        .collect();
+    crossterm::execute!(
+        io::stdout(),
+        crossterm::terminal::LeaveAlternateScreen,
+        crossterm::event::DisableBracketedPaste,
+        crossterm::terminal::Clear(crossterm::terminal::ClearType::All),
+        crossterm::cursor::MoveTo(0, 0),
+        crossterm::style::Print(text)
+    )?;
+    io::stdout().flush()?;
+    Ok(())
+}
+
+fn leave_plain_text_mode() -> Result<()> {
+    crossterm::execute!(
+        io::stdout(),
+        crossterm::terminal::EnterAlternateScreen,
+        crossterm::event::EnableBracketedPaste
+    )?;
+    Ok(())
+}
+
 fn sync_player_shared(state: &mut AppState, runtime: &Runtime) {
     if state.device_playback.is_control() {
         extrapolate_control_position(state);
@@ -453,6 +566,7 @@ fn apply_playback_state_to_ui(
         .filter(|track| update::track_allowed_by_source_mode(state, track))
         .collect();
     state.player.queue_pos = queue_pos.min(state.player.queue.len().saturating_sub(1));
+    state.player.play_next_end = None;
     state.player.playing = wire.playing && !state.player.queue.is_empty();
     state.player.paused = wire.paused;
     state.device_playback.local_idle_since_ms = if state.player.playing && !state.player.paused {
@@ -1331,6 +1445,14 @@ fn perform_effect(state: &mut AppState, runtime: &mut Runtime, effect: Effect) {
         }
         Effect::SetOptions => {}
         Effect::PlaybackQueueChanged => {}
+        Effect::QueueOrderChanged { restart_current } => {
+            if restart_current && state.player.playing && state.player.current.is_some() {
+                let paused = state.player.paused;
+                start_current_audio(state, runtime, state.player.position_secs, paused);
+                push_media_metadata(state, runtime);
+                push_media_update(state, runtime, true);
+            }
+        }
         Effect::SourceModeChanged => {
             runtime.library_network_refresh_at = None;
             if let Ok(mut cursors) = runtime.library_network_cursors.lock() {
@@ -1349,6 +1471,30 @@ fn perform_effect(state: &mut AppState, runtime: &mut Runtime, effect: Effect) {
                 perform_effect(state, runtime, effect);
             }
         }
+        Effect::ChangeMusicDirectory {
+            path,
+            move_existing,
+        } => {
+            if state.music_dir_changing {
+                state.status_message = Some("music directory change is already running".into());
+                return;
+            }
+            state.music_dir_changing = true;
+            state.status_message = Some(if move_existing {
+                "moving saved music to the new directory…".into()
+            } else {
+                "changing music save directory…".into()
+            });
+            let federation = Arc::clone(&runtime.federation);
+            let tx = runtime.event_tx.clone();
+            tokio::spawn(async move {
+                let result = federation
+                    .change_media_dir(path, move_existing)
+                    .await
+                    .map_err(err_string);
+                let _ = tx.send(AppEvent::MusicDirectoryChanged(result));
+            });
+        }
         Effect::EnqueueRelease { id, next } => {
             let library = Arc::clone(&runtime.library);
             let tx = runtime.event_tx.clone();
@@ -1478,6 +1624,15 @@ fn perform_effect(state: &mut AppState, runtime: &mut Runtime, effect: Effect) {
                 let _ = tx.send(event);
             });
         }
+        Effect::SimilarityApplySettings => {
+            save_app_settings(state);
+            runtime.similarity.apply(state.similarity.settings.clone());
+            state.similarity.status = runtime.similarity.status();
+        }
+        Effect::SimilarityClear => {
+            state.status_message = Some("clearing stored embeddings…".to_string());
+            runtime.similarity.clear();
+        }
         Effect::FedApplySettings => fed_apply_settings(state, runtime),
         Effect::FedSyncNow => {
             state.federation.publishing = true;
@@ -1733,6 +1888,7 @@ fn is_controlled_playback_effect(effect: &Effect) -> bool {
             | Effect::SetOptions
             | Effect::RemoveQueueIndices { .. }
             | Effect::PlaybackQueueChanged
+            | Effect::QueueOrderChanged { .. }
     )
 }
 
@@ -1766,7 +1922,9 @@ fn perform_control_playback_effect(state: &mut AppState, runtime: &mut Runtime,
         Effect::SetOptions
         | Effect::RemoveQueueIndices { .. }
         | Effect::PlaybackQueueChanged
-        | Effect::LoadListenHistory => {}
+        | Effect::QueueOrderChanged { .. }
+        | Effect::LoadListenHistory
+        | Effect::ChangeMusicDirectory { .. } => {}
         _ => {}
     }
     if local_only_volume {
@@ -2618,7 +2776,12 @@ fn on_library_changed(state: &mut AppState, runtime: &mut Runtime) {
     // until then.
     state.likes_loaded = false;
     state.local_content_ids_loaded = false;
-    state.local_library_stats = None;
+    // Refresh in place: status cards keep the last successful snapshot
+    // instead of flashing `loading` for every background library event.
+    if state.local_library_stats.is_none() {
+        state.local_library_stats = Some(state::Loadable::Loading);
+    }
+    refresh_local_library_stats(runtime);
 
     // Fresh copies of whatever sits in the queue. Federated placeholders
     // and ephemeral tracks (negative ids) are not library rows and keep
@@ -2678,6 +2841,8 @@ fn save_app_settings(state: &AppState) {
     let settings = crate::config::settings::AppSettings {
         volume: state.player.volume,
         library: state.global.filters,
+        music_dir: state.music_dir.clone(),
+        similarity: state.similarity.settings.clone(),
     };
     if let Err(err) = crate::config::settings::save(&settings) {
         tracing::warn!(%err, "saving app settings failed");
@@ -2939,6 +3104,48 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
                 Err(err) => state::Loadable::Failed(err),
             });
         }
+        AppEvent::MusicDirectoryValidated(result) => {
+            state.music_dir_changing = false;
+            match result {
+                Ok(path) => {
+                    let current = std::fs::canonicalize(&state.music_dir)
+                        .unwrap_or_else(|_| state.music_dir.clone());
+                    if path == current {
+                        state.status_message =
+                            Some("this is already the music save directory".into());
+                    } else {
+                        state.popup = Some(state::Popup::ConfirmMusicDirectory { path });
+                        state.status_message = None;
+                    }
+                }
+                Err(message) => {
+                    state.status_message = Some(format!(
+                        "music directory is not writable; nothing changed: {message}"
+                    ));
+                }
+            }
+        }
+        AppEvent::MusicDirectoryChanged(result) => {
+            state.music_dir_changing = false;
+            match result {
+                Ok(stats) => {
+                    state.music_dir = runtime.federation.media_dir();
+                    save_app_settings(state);
+                    state.status_message = Some(format!(
+                        "music directory changed · moved {} track(s), {} image(s)",
+                        stats.tracks, stats.images
+                    ));
+                    let _ = runtime.event_tx.send(AppEvent::LibraryChanged {
+                        message: state.status_message.clone(),
+                    });
+                }
+                Err(message) => {
+                    state.status_message = Some(format!(
+                        "music directory change failed; old library kept: {message}"
+                    ));
+                }
+            }
+        }
         AppEvent::FederationStatus(status) => {
             state.federation.status = Some(status);
         }
@@ -3018,6 +3225,7 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
                     title: "Device invite".to_string(),
                     text: invite,
                     help: "Use this invite on another client within 10 minutes to pair it with this device group.".to_string(),
+                    cursor: 0,
                 });
                 state.status_message = Some("device invite generated".to_string());
             }
@@ -3117,6 +3325,7 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
                     title: "Jam invite".to_string(),
                     text: invite,
                     help: "Copied capability lets federation peers control this host player until restart or regeneration.".to_string(),
+                    cursor: 0,
                 });
                 state.status_message = Some("Jam started".into());
             }
@@ -3139,6 +3348,39 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
                 Err(message) => tracing::warn!(%message, "federated search failed"),
             }
         }
+        AppEvent::FedSimilaritySearchLoaded { seq, result } => {
+            if runtime.search_seq.load(std::sync::atomic::Ordering::SeqCst) != seq {
+                return;
+            }
+            state.search.fed_loading = false;
+            let selected_key = state.global.stack.last().and_then(|view| match view {
+                state::GlobalView::Search { cursor } => state.search.similarity_key(*cursor),
+                _ => None,
+            });
+            match result {
+                Ok(results) => {
+                    let remote = results.tracks.into_iter().map(|hit| {
+                        state::SimilaritySearchHit::Federated {
+                            track: hit.track,
+                            score: hit.score,
+                            embedding_signature: hit.embedding_signature,
+                        }
+                    });
+                    state.search.similarity_tracks.extend(remote);
+                    rank_similarity_search_tracks(
+                        &mut state.search.similarity_tracks,
+                        state.similarity.settings.max_tracks_per_artist,
+                    );
+                    state.search.similarity_stats = Some(results.stats);
+                    state.search.similarity_error = None;
+                }
+                Err(message) => {
+                    tracing::warn!(%message, "federated similarity search failed");
+                    state.search.similarity_error = Some(message);
+                }
+            }
+            restore_similarity_cursor(state, selected_key.as_deref());
+        }
         AppEvent::FedTrackResolved {
             placeholder_id,
             resolve_key,
@@ -3273,6 +3515,7 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
                         // Skip the failed track instead of stalling the queue.
                         if state.player.queue_pos + 1 < state.player.queue.len() {
                             state.player.queue_pos += 1;
+                            update::normalize_play_next_block(&mut state.player);
                             start_current_audio(state, runtime, 0.0, state.player.paused);
                             push_media_metadata(state, runtime);
                             push_media_update(state, runtime, true);
@@ -3374,6 +3617,7 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
                     text: ticket,
                     help: "Copy this ticket and paste it into Connect to a peer on another client."
                         .to_string(),
+                    cursor: 0,
                 });
             }
             Err(message) => state.status_message = Some(message),
@@ -3479,6 +3723,53 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
                 Err(message) => state.status_message = Some(message),
             }
         }
+        AppEvent::SimilaritySearchLoaded { seq, result, query } => {
+            if seq != runtime.search_seq.load(std::sync::atomic::Ordering::SeqCst) {
+                return;
+            }
+            state.search.loading = false;
+            match result {
+                Ok(results) => {
+                    state.search.similarity_tracks = results
+                        .into_iter()
+                        .map(|hit| state::SimilaritySearchHit::Local {
+                            track: hit.track,
+                            score: hit.score,
+                            embedding_signature: hit.embedding_signature,
+                        })
+                        .collect();
+                    rank_similarity_search_tracks(
+                        &mut state.search.similarity_tracks,
+                        state.similarity.settings.max_tracks_per_artist,
+                    );
+                }
+                Err(message) => {
+                    state.status_message = Some(format!("similarity search failed: {message}"));
+                    return;
+                }
+            }
+            if let Some(query) = query
+                && state.federation.settings.enabled
+                && runtime.similarity.network_allowed()
+            {
+                state.search.fed_loading = true;
+                let federation = Arc::clone(&runtime.federation);
+                let tx = runtime.event_tx.clone();
+                tokio::spawn(async move {
+                    let result = federation
+                        .search_similar(query, 50)
+                        .await
+                        .map_err(|err| format!("{err:#}"));
+                    let _ = tx.send(AppEvent::FedSimilaritySearchLoaded { seq, result });
+                });
+            }
+        }
+        AppEvent::SimilarityStatus(status) => state.similarity.status = status,
+        AppEvent::SimilarityProfileActivated(profile_id) => {
+            state.similarity.settings.active_profile = profile_id;
+            state.similarity.status = runtime.similarity.status();
+            save_app_settings(state);
+        }
         AppEvent::ArtLoaded { key, art } => {
             let entry = match art {
                 Some(image) => state::ArtState::Ready(image),
@@ -3516,6 +3807,7 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
                     .take()
                     .unwrap_or(state.player.queue_pos + 1);
                 state.player.queue_pos = next_pos.min(state.player.queue.len().saturating_sub(1));
+                update::normalize_play_next_block(&mut state.player);
                 state.player.current = state.player.queue.get(state.player.queue_pos).cloned();
                 state.player.position_secs = 0.0;
                 state.player.track_started_at = Some(now_epoch_seconds());
@@ -3581,15 +3873,17 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
                 tracing::warn!(%message, "local content id load failed");
             }
         },
-        AppEvent::LocalLibraryStatsLoaded(result) => {
-            state.local_library_stats = Some(match result {
-                Ok(stats) => state::Loadable::Ready(stats),
-                Err(message) => {
-                    tracing::warn!(%message, "local library stats load failed");
-                    state::Loadable::Failed(message)
+        AppEvent::LocalLibraryStatsLoaded(result) => match result {
+            Ok(stats) => {
+                state.local_library_stats = Some(state::Loadable::Ready(stats));
+            }
+            Err(message) => {
+                tracing::warn!(%message, "local library stats load failed");
+                if !matches!(state.local_library_stats, Some(state::Loadable::Ready(_))) {
+                    state.local_library_stats = Some(state::Loadable::Failed(message));
                 }
-            });
-        }
+            }
+        },
         AppEvent::LocalContentAvailable { content_id } => {
             if let Some(content_id) = music_dht::normalize_content_id(&content_id) {
                 state.local_content_ids.insert(content_id);
@@ -3648,9 +3942,13 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
         }
         AppEvent::EnqueueTracks { tracks, next } => {
             let previous_len = state.player.queue.len();
-            update::enqueue_tracks(state, tracks, next);
+            let restart_current = update::enqueue_tracks(state, tracks, next);
             let count = state.player.queue.len().saturating_sub(previous_len);
-            record_control_playback_state(state, runtime, false);
+            perform_effect(
+                state,
+                runtime,
+                Effect::QueueOrderChanged { restart_current },
+            );
             state.status_message = Some(if count == 0 {
                 "no tracks available in the current source mode".to_string()
             } else if next {
@@ -3699,6 +3997,9 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
         }
         AppEvent::LibraryChanged { message } => {
             on_library_changed(state, runtime);
+            if state.similarity.settings.enabled {
+                runtime.similarity.start();
+            }
             if let Some(message) = message {
                 state.status_message = Some(message);
             }
@@ -3752,6 +4053,135 @@ fn handle_app_event(state: &mut AppState, runtime: &mut Runtime, event: AppEvent
     }
 }
 
+fn rank_similarity_search_tracks(
+    tracks: &mut Vec<state::SimilaritySearchHit>,
+    max_tracks_per_artist: usize,
+) {
+    const RESULT_LIMIT: usize = 49;
+    const MAX_NEAR_DUPLICATE_SIGNATURE_DISTANCE: u32 = 8;
+
+    tracks.sort_by(|left, right| right.score().total_cmp(&left.score()));
+    let candidates = std::mem::take(tracks);
+    let mut content = std::collections::HashSet::new();
+    let mut signatures = Vec::new();
+    let mut artist_counts: std::collections::HashMap<String, usize> = Default::default();
+    for hit in candidates {
+        if !content.insert(hit.content_key()) {
+            continue;
+        }
+        if hit.embedding_signature().is_some_and(|candidate| {
+            signatures.iter().any(|existing| {
+                music_dht::similarity::signature_distance(&candidate, existing)
+                    <= MAX_NEAR_DUPLICATE_SIGNATURE_DISTANCE
+            })
+        }) {
+            continue;
+        }
+        let artist = hit.primary_artist_key();
+        let count = artist_counts.entry(artist.clone()).or_default();
+        if !artist.is_empty() && *count >= max_tracks_per_artist.clamp(1, RESULT_LIMIT) {
+            continue;
+        }
+        *count += 1;
+        if let Some(signature) = hit.embedding_signature() {
+            signatures.push(signature);
+        }
+        tracks.push(hit);
+        if tracks.len() >= RESULT_LIMIT {
+            break;
+        }
+    }
+}
+
+fn restore_similarity_cursor(state: &mut AppState, selected_key: Option<&str>) {
+    let selected_index = selected_key.and_then(|key| state.search.similarity_index_for_key(key));
+    let len = state.search.similarity_len();
+    if let Some(state::GlobalView::Search { cursor }) = state.global.stack.last_mut() {
+        *cursor = selected_index.unwrap_or(*cursor).min(len.saturating_sub(1));
+    }
+}
+
+#[cfg(test)]
+mod similarity_search_tests {
+    use super::*;
+    use crate::library::models::{ArtistRef, TrackItem};
+
+    fn local_hit(id: i64, artist: &str, score: f32, signature: u8) -> state::SimilaritySearchHit {
+        state::SimilaritySearchHit::Local {
+            track: TrackItem {
+                id,
+                title: format!("local {id}"),
+                track_number: None,
+                disc_number: None,
+                duration_seconds: 1.0,
+                artists: vec![ArtistRef {
+                    id,
+                    name: artist.to_string(),
+                }],
+                featured_artists: Vec::new(),
+                release_id: id,
+                release_title: "release".to_string(),
+                release_year: None,
+                file_path: format!("/music/{id}"),
+                content_id: Some(format!("local-{id}")),
+                cover_path: None,
+                audio_format: None,
+                audio_bitrate: None,
+                audio_sample_rate: None,
+                audio_bit_depth: None,
+                file_size_bytes: None,
+                play_count: 0,
+                fed: None,
+            },
+            score,
+            embedding_signature: [signature; music_dht::similarity::SIMILARITY_SIGNATURE_BYTES],
+        }
+    }
+
+    fn remote_hit(artist: &str, score: f32, signature: u8) -> state::SimilaritySearchHit {
+        state::SimilaritySearchHit::Federated {
+            track: crate::federation::FedTrack {
+                item_id: format!("remote-{signature}"),
+                owner: "peer".to_string(),
+                own: false,
+                title: format!("remote {signature}"),
+                artist_names: vec![artist.to_string()],
+                featured_artist_names: Vec::new(),
+                year: None,
+                duration_seconds: Some(1),
+                content_id: Some(format!("remote-{signature}")),
+                release_title: None,
+                track_number: None,
+                disc_number: None,
+            },
+            score,
+            embedding_signature: Some(
+                [signature; music_dht::similarity::SIMILARITY_SIGNATURE_BYTES],
+            ),
+        }
+    }
+
+    #[test]
+    fn similarity_results_rank_local_and_remote_together_with_one_artist_cap() {
+        let mut tracks = vec![
+            local_hit(1, "same artist", 0.70, 1),
+            remote_hit("other artist", 0.90, 2),
+            remote_hit("same artist", 0.80, 3),
+            local_hit(2, "same artist", 0.60, 4),
+        ];
+
+        rank_similarity_search_tracks(&mut tracks, 1);
+
+        assert_eq!(tracks.len(), 2);
+        assert_eq!(tracks[0].score(), 0.90);
+        assert_eq!(tracks[1].score(), 0.80);
+        assert!(matches!(
+            tracks[0],
+            state::SimilaritySearchHit::Federated { .. }
+        ));
+    }
+}
+
 /// Mirror the playback state to the OS now-playing surface. `force` skips
 /// the position throttle (track switches, pauses).
 fn push_media_update(state: &AppState, runtime: &mut Runtime, force: bool) {

src/app/popup.rs

@@ -115,6 +115,39 @@ pub fn handle_key(state: &mut AppState, runtime: &mut Runtime, key: KeyEvent) {
         Popup::ConfirmDelete { target, label } => {
             handle_confirm_delete(state, runtime, target, label, key);
         }
+        Popup::SimilarityPrivacyConsent { enable_federation } => match key.code {
+            KeyCode::Enter | KeyCode::Char('y') => {
+                state.similarity.settings.federation_consent = true;
+                state.similarity.settings.enabled = true;
+                super::perform_effect(
+                    state,
+                    runtime,
+                    crate::app::update::Effect::SimilarityApplySettings,
+                );
+                if enable_federation {
+                    super::perform_effect(
+                        state,
+                        runtime,
+                        crate::app::update::Effect::FedApplySettings,
+                    );
+                }
+            }
+            KeyCode::Esc | KeyCode::Char('n') | KeyCode::Char('q') => {
+                if enable_federation {
+                    state.federation.settings.enabled = false;
+                }
+            }
+            _ => {
+                state.popup = Some(Popup::SimilarityPrivacyConsent { enable_federation });
+            }
+        },
+        Popup::ConfirmClearEmbeddings => match key.code {
+            KeyCode::Enter | KeyCode::Char('y') => {
+                super::perform_effect(state, runtime, crate::app::update::Effect::SimilarityClear)
+            }
+            KeyCode::Esc | KeyCode::Char('n') | KeyCode::Char('q') => {}
+            _ => state.popup = Some(Popup::ConfirmClearEmbeddings),
+        },
         Popup::LibraryFilters { cursor } => handle_library_filters(state, runtime, cursor, key),
         Popup::TrackInfo {
             tracks,
@@ -136,17 +169,52 @@ pub fn handle_key(state: &mut AppState, runtime: &mut Runtime, key: KeyEvent) {
             KeyCode::Esc | KeyCode::Enter | KeyCode::Char('q') => {}
             _ => state.popup = Some(Popup::FedText { title, text }),
         },
-        Popup::FedCopyText { title, text, help } => match key.code {
+        Popup::FedCopyText {
+            title,
+            text,
+            help,
+            mut cursor,
+        } => match key.code {
             KeyCode::Esc | KeyCode::Char('q') => {}
+            KeyCode::Left | KeyCode::Right | KeyCode::Tab | KeyCode::BackTab => {
+                cursor = usize::from(cursor == 0);
+                state.popup = Some(Popup::FedCopyText {
+                    title,
+                    text,
+                    help,
+                    cursor,
+                });
+            }
+            KeyCode::Enter if cursor == 1 => state.popup = Some(Popup::PlainText { text }),
+            KeyCode::Char('p') => state.popup = Some(Popup::PlainText { text }),
             KeyCode::Enter | KeyCode::Char('c') => match copy_to_clipboard(&text) {
                 Ok(()) => state.status_message = Some("copied to clipboard".to_string()),
                 Err(err) => {
                     state.status_message = Some(format!("copy failed: {err}"));
-                    state.popup = Some(Popup::FedCopyText { title, text, help });
+                    state.popup = Some(Popup::FedCopyText {
+                        title,
+                        text,
+                        help,
+                        cursor,
+                    });
                 }
             },
-            _ => state.popup = Some(Popup::FedCopyText { title, text, help }),
+            _ => {
+                state.popup = Some(Popup::FedCopyText {
+                    title,
+                    text,
+                    help,
+                    cursor,
+                })
+            }
         },
+        Popup::PlainText { text } => match key.code {
+            KeyCode::Esc => {}
+            _ => state.popup = Some(Popup::PlainText { text }),
+        },
+        Popup::ConfirmMusicDirectory { path } => {
+            handle_music_directory_confirmation(state, runtime, path, key)
+        }
         Popup::FederationStatusDetails {
             focus,
             status_cursor,
@@ -502,6 +570,58 @@ fn handle_fed_input(
                         !state.federation.settings.network_id.is_empty();
                     super::fed_apply_settings(state, runtime);
                 }
+                FedInputField::MusicDirectory => {
+                    if value.is_empty() {
+                        state.status_message = Some("music directory is empty".into());
+                    } else {
+                        super::validate_music_directory(state, runtime, value.into());
+                    }
+                }
+                FedInputField::SimilarityWorkers => match value.parse::<usize>() {
+                    Ok(workers @ 1..=16) => {
+                        state.similarity.settings.workers = workers;
+                        super::perform_effect(
+                            state,
+                            runtime,
+                            crate::app::update::Effect::SimilarityApplySettings,
+                        );
+                    }
+                    _ => {
+                        state.status_message =
+                            Some("similarity workers must be a number from 1 to 16".into());
+                        state.popup = Some(Popup::FedInput { field, input });
+                    }
+                },
+                FedInputField::SimilarityMinimumScore => match value.parse::<f32>() {
+                    Ok(score) if score.is_finite() && (0.0..=1.0).contains(&score) => {
+                        state.similarity.settings.minimum_score = score;
+                        super::perform_effect(
+                            state,
+                            runtime,
+                            crate::app::update::Effect::SimilarityApplySettings,
+                        );
+                    }
+                    _ => {
+                        state.status_message =
+                            Some("minimum similarity must be a number from 0.00 to 1.00".into());
+                        state.popup = Some(Popup::FedInput { field, input });
+                    }
+                },
+                FedInputField::SimilarityMaxTracksPerArtist => match value.parse::<usize>() {
+                    Ok(limit @ 1..=50) => {
+                        state.similarity.settings.max_tracks_per_artist = limit;
+                        super::perform_effect(
+                            state,
+                            runtime,
+                            crate::app::update::Effect::SimilarityApplySettings,
+                        );
+                    }
+                    _ => {
+                        state.status_message =
+                            Some("tracks per artist must be a number from 1 to 50".into());
+                        state.popup = Some(Popup::FedInput { field, input });
+                    }
+                },
                 FedInputField::ConnectTicket => {
                     if value.is_empty() {
                         state.status_message = Some("ticket is empty".into());
@@ -551,6 +671,31 @@ fn handle_fed_input(
     }
 }
 
+fn handle_music_directory_confirmation(
+    state: &mut AppState,
+    runtime: &mut Runtime,
+    path: std::path::PathBuf,
+    key: KeyEvent,
+) {
+    let move_existing = match key.code {
+        KeyCode::Esc | KeyCode::Char('q') => return,
+        KeyCode::Enter | KeyCode::Char('y') | KeyCode::Char('Y') => true,
+        KeyCode::Char('n') | KeyCode::Char('N') => false,
+        _ => {
+            state.popup = Some(Popup::ConfirmMusicDirectory { path });
+            return;
+        }
+    };
+    super::perform_effect(
+        state,
+        runtime,
+        crate::app::update::Effect::ChangeMusicDirectory {
+            path,
+            move_existing,
+        },
+    );
+}
+
 fn handle_device_pairing(
     state: &mut AppState,
     runtime: &Runtime,
@@ -934,10 +1079,15 @@ fn handle_track_info(
         KeyCode::Char('c') => {
             if let Some(track) = tracks.get(cursor.min(len.saturating_sub(1))) {
                 match crate::share::track_share_link(track) {
-                    Some(link) => match copy_to_clipboard(&link) {
-                        Ok(()) => state.status_message = Some("frid link copied".into()),
-                        Err(err) => state.status_message = Some(format!("copy failed: {err}")),
-                    },
+                    Some(link) => {
+                        state.popup = Some(Popup::FedCopyText {
+                            title: "Track share link".into(),
+                            text: link,
+                            help: "Copy the link with a clipboard helper, or show it as one clean terminal line for mouse selection.".into(),
+                            cursor: 0,
+                        });
+                        return;
+                    }
                     None => state.status_message = Some("no content id for this track yet".into()),
                 }
             }
@@ -947,6 +1097,28 @@ fn handle_track_info(
                 scroll,
             });
         }
+        KeyCode::Char('s') => {
+            let Some(track) = tracks.get(cursor.min(len.saturating_sub(1))) else {
+                return;
+            };
+            if !state.similarity.settings.enabled {
+                state.status_message = Some("enable Similarity search in Settings first".into());
+                state.popup = Some(Popup::TrackInfo {
+                    tracks,
+                    cursor,
+                    scroll,
+                });
+            } else if track.id < 0 || track.file_path.is_empty() {
+                state.status_message = Some("similarity search starts from a local track".into());
+                state.popup = Some(Popup::TrackInfo {
+                    tracks,
+                    cursor,
+                    scroll,
+                });
+            } else {
+                super::cmdline::schedule_similarity_search(state, runtime, track);
+            }
+        }
         _ => {
             state.popup = Some(Popup::TrackInfo {
                 tracks,

src/app/state.rs

@@ -389,6 +389,7 @@ mod tests {
             featured_tracks: Vec::new(),
         };
         let mut state = AppState::default();
+        state.global.filters.source_mode = crate::config::settings::LibrarySourceMode::Local;
         state.artist_fed_views.insert(
             detail.id,
             Loadable::Ready(crate::federation::FedArtistCard {
@@ -508,6 +509,8 @@ pub enum TrackSelectionScope {
     Release(i64),
     Playlist(i64),
     Queue,
+    /// The unified local + federated similar-track result list.
+    SimilaritySearch,
     /// The federated section of the search results (its tracks).
     FedSearch,
     /// The tracklist of the open federated release view.
@@ -686,6 +689,10 @@ pub enum Popup {
     },
     /// Delete confirmation; Enter/y deletes, Esc/n cancels.
     ConfirmDelete { target: DeleteTarget, label: String },
+    /// Enabling network similarity reveals an embedding query to peers.
+    SimilarityPrivacyConsent { enable_federation: bool },
+    /// Derived data is safe to recreate but potentially expensive.
+    ConfirmClearEmbeddings,
     /// Library-home filters. Cursor is kept for the next filters added here.
     LibraryFilters { cursor: usize },
     /// Track metadata viewer; left/right switch between selected tracks.
@@ -716,7 +723,16 @@ pub enum Popup {
         title: String,
         text: String,
         help: String,
+        cursor: usize,
     },
+    /// A copy-friendly terminal screen containing exactly one logical line.
+    /// The app loop temporarily leaves the alternate screen while this is
+    /// active so terminal selection does not acquire TUI borders or hard
+    /// line breaks.
+    PlainText { text: String },
+    /// The destination is already write-tested; Enter/y migrates managed
+    /// files, while n changes only the destination for future downloads.
+    ConfirmMusicDirectory { path: std::path::PathBuf },
     /// Incoming trusted-device pairing request.
     DevicePairing {
         request_id: String,
@@ -801,6 +817,10 @@ impl StatusDetailFocus {
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum FedInputField {
+    MusicDirectory,
+    SimilarityWorkers,
+    SimilarityMinimumScore,
+    SimilarityMaxTracksPerArtist,
     NetworkId,
     ConnectTicket,
     DeviceName,
@@ -811,6 +831,10 @@ pub enum FedInputField {
 impl FedInputField {
     pub fn title(self) -> &'static str {
         match self {
+            FedInputField::MusicDirectory => "Music save directory",
+            FedInputField::SimilarityWorkers => "Similarity background workers",
+            FedInputField::SimilarityMinimumScore => "Minimum similarity score",
+            FedInputField::SimilarityMaxTracksPerArtist => "Tracks per artist",
             FedInputField::NetworkId => "Network ID",
             FedInputField::ConnectTicket => "Connect to peer (paste ticket)",
             FedInputField::DeviceName => "Device name",
@@ -821,6 +845,18 @@ impl FedInputField {
 
     pub fn help(self) -> &'static str {
         match self {
+            FedInputField::MusicDirectory => {
+                "Federated tracks saved to your library use this directory. The directory is checked for write access before anything changes."
+            }
+            FedInputField::SimilarityWorkers => {
+                "Enter the maximum number of tracks processed in parallel, from 1 to 16. The change takes effect immediately."
+            }
+            FedInputField::SimilarityMinimumScore => {
+                "Enter the minimum cosine similarity from 0.00 to 1.00. Lower values show broader matches; higher values hide weak matches. Embeddings are not recalculated."
+            }
+            FedInputField::SimilarityMaxTracksPerArtist => {
+                "Enter how many tracks by one primary artist may appear in similarity results, from 1 to 50. Embeddings are not recalculated."
+            }
             FedInputField::NetworkId => {
                 "A unique network id. It must match exactly on every client that should see and connect to the same peers."
             }
@@ -851,6 +887,29 @@ pub enum FedRow {
     Connect,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SimilarityRow {
+    Toggle,
+    Model,
+    Profile,
+    MinimumScore,
+    MaxTracksPerArtist,
+    Workers,
+    Clear,
+}
+
+impl SimilarityRow {
+    pub const ALL: [SimilarityRow; 7] = [
+        SimilarityRow::Toggle,
+        SimilarityRow::Model,
+        SimilarityRow::Profile,
+        SimilarityRow::MinimumScore,
+        SimilarityRow::MaxTracksPerArtist,
+        SimilarityRow::Workers,
+        SimilarityRow::Clear,
+    ];
+}
+
 impl FedRow {
     pub const ALL: [FedRow; 6] = [
         FedRow::Toggle,
@@ -867,6 +926,8 @@ impl FedRow {
 /// the config directory.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum SettingsRow {
+    MusicDirectory,
+    Similarity(SimilarityRow),
     Federation(FedRow),
     StatusDetails,
     DeviceName,
@@ -1004,7 +1065,8 @@ pub fn device_status_order(state: &AppState) -> Vec<usize> {
 }
 
 pub fn settings_rows(state: &AppState) -> Vec<SettingsRow> {
-    let mut rows = Vec::new();
+    let mut rows = vec![SettingsRow::MusicDirectory];
+    rows.extend(SimilarityRow::ALL.into_iter().map(SettingsRow::Similarity));
     rows.extend(FedRow::ALL.into_iter().map(SettingsRow::Federation));
     rows.push(SettingsRow::DeviceName);
     rows.push(SettingsRow::DeviceInvite);
@@ -1043,6 +1105,12 @@ pub struct FederationTab {
     pub device_syncing: bool,
 }
 
+#[derive(Debug, Default)]
+pub struct SimilarityTab {
+    pub settings: crate::config::settings::SimilaritySettings,
+    pub status: crate::similarity::SimilarityStatus,
+}
+
 /// Playlists eligible as add-targets (the virtual Likes playlist is managed
 /// through likes, not direct adds).
 pub fn addable_playlists(state: &AppState) -> Vec<(i64, String)> {
@@ -1064,9 +1132,180 @@ pub struct Cmdline {
     /// A live command (search) applied effects during this session; Esc
     /// undoes them, Enter keeps them.
     pub live: bool,
+    /// Commands committed during this process, oldest first.
+    pub history: Vec<String>,
+    /// Entry currently recalled with Up/Down. `None` is the editable draft
+    /// after the newest history entry.
+    history_index: Option<usize>,
+    history_draft: String,
+}
+
+impl Cmdline {
+    const HISTORY_LIMIT: usize = 100;
+
+    pub fn begin_history_navigation(&mut self) {
+        self.history_index = None;
+        self.history_draft.clear();
+    }
+
+    pub fn remember(&mut self, value: &str) {
+        let value = value.trim();
+        if value.is_empty() {
+            return;
+        }
+        if self.history.last().is_none_or(|last| last != value) {
+            self.history.push(value.to_string());
+            if self.history.len() > Self::HISTORY_LIMIT {
+                self.history.remove(0);
+            }
+        }
+        self.begin_history_navigation();
+    }
+
+    pub fn history_previous(&mut self) -> bool {
+        if self.history.is_empty() {
+            return false;
+        }
+        let index = match self.history_index {
+            Some(index) => index.saturating_sub(1),
+            None => {
+                self.history_draft = self.input.as_str().to_string();
+                self.history.len() - 1
+            }
+        };
+        self.history_index = Some(index);
+        self.input = LineEdit::new(self.history[index].clone());
+        true
+    }
+
+    pub fn history_next(&mut self) -> bool {
+        let Some(index) = self.history_index else {
+            return false;
+        };
+        if index + 1 < self.history.len() {
+            self.history_index = Some(index + 1);
+            self.input = LineEdit::new(self.history[index + 1].clone());
+        } else {
+            self.history_index = None;
+            self.input = LineEdit::new(std::mem::take(&mut self.history_draft));
+        }
+        true
+    }
+}
+
+#[cfg(test)]
+mod cmdline_history_tests {
+    use super::Cmdline;
+    use crate::app::input::LineEdit;
+
+    #[test]
+    fn history_walks_oldest_and_restores_the_draft() {
+        let mut cmdline = Cmdline::default();
+        cmdline.remember("volume 20");
+        cmdline.remember("/ambient");
+        cmdline.input = LineEdit::new("unfinished");
+
+        assert!(cmdline.history_previous());
+        assert_eq!(cmdline.input.as_str(), "/ambient");
+        assert!(cmdline.history_previous());
+        assert_eq!(cmdline.input.as_str(), "volume 20");
+        assert!(cmdline.history_previous());
+        assert_eq!(cmdline.input.as_str(), "volume 20");
+        assert!(cmdline.history_next());
+        assert_eq!(cmdline.input.as_str(), "/ambient");
+        assert!(cmdline.history_next());
+        assert_eq!(cmdline.input.as_str(), "unfinished");
+    }
+
+    #[test]
+    fn history_deduplicates_consecutive_commands() {
+        let mut cmdline = Cmdline::default();
+        cmdline.remember("q");
+        cmdline.remember(" q ");
+        assert_eq!(cmdline.history, vec!["q"]);
+    }
 }
 
 /// Live search state driven by the `:/query` command.
+#[derive(Debug, Clone)]
+pub enum SimilaritySearchHit {
+    Local {
+        track: TrackItem,
+        score: f32,
+        embedding_signature: [u8; music_dht::similarity::SIMILARITY_SIGNATURE_BYTES],
+    },
+    Federated {
+        track: crate::federation::FedTrack,
+        score: f32,
+        embedding_signature: Option<[u8; music_dht::similarity::SIMILARITY_SIGNATURE_BYTES]>,
+    },
+}
+
+impl SimilaritySearchHit {
+    pub fn score(&self) -> f32 {
+        match self {
+            Self::Local { score, .. } | Self::Federated { score, .. } => *score,
+        }
+    }
+
+    pub fn embedding_signature(
+        &self,
+    ) -> Option<[u8; music_dht::similarity::SIMILARITY_SIGNATURE_BYTES]> {
+        match self {
+            Self::Local {
+                embedding_signature,
+                ..
+            } => Some(*embedding_signature),
+            Self::Federated {
+                embedding_signature,
+                ..
+            } => *embedding_signature,
+        }
+    }
+
+    pub fn track_item(&self) -> TrackItem {
+        match self {
+            Self::Local { track, .. } => track.clone(),
+            Self::Federated { track, .. } => crate::federation::pending_track(track),
+        }
+    }
+
+    pub fn federated_track(&self) -> Option<&crate::federation::FedTrack> {
+        match self {
+            Self::Federated { track, .. } => Some(track),
+            Self::Local { .. } => None,
+        }
+    }
+
+    pub fn primary_artist_key(&self) -> String {
+        match self {
+            Self::Local { track, .. } => track
+                .artists
+                .first()
+                .map(|artist| music_dht::normalize_name(&artist.name))
+                .unwrap_or_default(),
+            Self::Federated { track, .. } => track
+                .artist_names
+                .first()
+                .map(|artist| music_dht::normalize_name(artist))
+                .unwrap_or_default(),
+        }
+    }
+
+    pub fn content_key(&self) -> String {
+        match self {
+            Self::Local { track, .. } => track
+                .content_id
+                .clone()
+                .unwrap_or_else(|| format!("local:{}", track.id)),
+            Self::Federated { track, .. } => track
+                .content_id
+                .clone()
+                .unwrap_or_else(|| format!("remote:{}:{}", track.owner, track.item_id)),
+        }
+    }
+}
+
 #[derive(Debug, Default)]
 pub struct SearchState {
     pub query: String,
@@ -1079,6 +1318,62 @@ pub struct SearchState {
     /// from the artist names of matching tracks.
     pub fed_artists: Vec<crate::federation::FedArtistHit>,
     pub fed_loading: bool,
+    /// Present only for a track-seeded search; text-search refreshes must not
+    /// replace this page with a title query.
+    pub similarity_source: Option<i64>,
+    /// The source is pinned at row zero; candidates below it are globally
+    /// ranked across the local library and federation.
+    pub similarity_source_track: Option<TrackItem>,
+    pub similarity_tracks: Vec<SimilaritySearchHit>,
+    pub similarity_stats: Option<crate::federation::SimilaritySearchStats>,
+    pub similarity_error: Option<String>,
+}
+
+impl SearchState {
+    pub fn similarity_len(&self) -> usize {
+        usize::from(self.similarity_source_track.is_some()) + self.similarity_tracks.len()
+    }
+
+    pub fn similarity_track(&self, index: usize) -> Option<TrackItem> {
+        if index == 0 {
+            return self.similarity_source_track.clone();
+        }
+        self.similarity_tracks
+            .get(index.checked_sub(1)?)
+            .map(SimilaritySearchHit::track_item)
+    }
+
+    pub fn similarity_fed_track(&self, index: usize) -> Option<&crate::federation::FedTrack> {
+        self.similarity_tracks
+            .get(index.checked_sub(1)?)?
+            .federated_track()
+    }
+
+    pub fn similarity_key(&self, index: usize) -> Option<String> {
+        if index == 0 {
+            return self
+                .similarity_source_track
+                .as_ref()
+                .map(|track| format!("source:{}", track.id));
+        }
+        self.similarity_tracks
+            .get(index.checked_sub(1)?)
+            .map(SimilaritySearchHit::content_key)
+    }
+
+    pub fn similarity_index_for_key(&self, key: &str) -> Option<usize> {
+        if self
+            .similarity_source_track
+            .as_ref()
+            .is_some_and(|track| key == format!("source:{}", track.id))
+        {
+            return Some(0);
+        }
+        self.similarity_tracks
+            .iter()
+            .position(|hit| hit.content_key() == key)
+            .map(|index| index + 1)
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
@@ -1169,6 +1464,9 @@ impl RepeatMode {
 pub struct PlayerBar {
     pub queue: Vec<TrackItem>,
     pub queue_pos: usize,
+    /// Exclusive end of the contiguous "play next" block built by
+    /// sequential `a` actions. New `a` additions are inserted here.
+    pub play_next_end: Option<usize>,
     pub current: Option<TrackItem>,
     /// A track is loaded (playing or paused); false = stopped.
     pub playing: bool,
@@ -1194,6 +1492,7 @@ impl Default for PlayerBar {
         Self {
             queue: Vec::new(),
             queue_pos: 0,
+            play_next_end: None,
             current: None,
             playing: false,
             paused: false,
@@ -1283,6 +1582,9 @@ pub struct AppState {
     pub status_message: Option<String>,
     pub spinner_frame: usize,
     pub settings_cursor: usize,
+    /// Root for music permanently downloaded from federation peers.
+    pub music_dir: std::path::PathBuf,
+    pub music_dir_changing: bool,
     pub player: PlayerBar,
     pub device_playback: DevicePlaybackState,
     pub jam: crate::jam::JamStatus,
@@ -1308,6 +1610,7 @@ pub struct AppState {
     pub logs: LogsTab,
     pub queue_tab: QueueTab,
     pub federation: FederationTab,
+    pub similarity: SimilarityTab,
     /// The one federated artist card being viewed (name + loading state);
     /// opening another card replaces it.
     pub fed_artist_view: Option<(String, Loadable<crate::federation::FedArtistCard>)>,

src/app/update.rs

@@ -48,10 +48,24 @@ pub enum Effect {
     },
     /// Queue/options changed without a direct audio engine action.
     PlaybackQueueChanged,
+    /// Queue order changed. A decoded gapless-next source must be discarded
+    /// by restarting the current source at its current position.
+    QueueOrderChanged {
+        restart_current: bool,
+    },
     /// Persist and apply a Local / My / Global source-mode change.
     SourceModeChanged,
+    /// Switch the permanent federation-download root, optionally relocating
+    /// files managed under the previous root first.
+    ChangeMusicDirectory {
+        path: std::path::PathBuf,
+        move_existing: bool,
+    },
     /// Persist the federation settings and start/stop the node.
     FedApplySettings,
+    /// Persist/apply embedding model, profile, worker or enable changes.
+    SimilarityApplySettings,
+    SimilarityClear,
     /// Force an immediate library publish into the DHT.
     FedSyncNow,
     /// Fetch this peer's ticket and show it in a popup.
@@ -180,6 +194,7 @@ pub fn update(state: &mut AppState, action: Action) -> Option<Effect> {
         }
         Action::ToggleShuffle => {
             state.player.shuffle = !state.player.shuffle;
+            state.player.play_next_end = None;
             // Shuffle physically reorders the unplayed tail, so the Queue
             // tab always shows the real upcoming order; turning it off
             // restores the original ordering.
@@ -275,6 +290,7 @@ pub fn update(state: &mut AppState, action: Action) -> Option<Effect> {
         Action::OpenCommandLine => {
             state.cmdline.active = true;
             state.cmdline.input.clear();
+            state.cmdline.begin_history_navigation();
             None
         }
         Action::OpenSearch => {
@@ -283,6 +299,7 @@ pub fn update(state: &mut AppState, action: Action) -> Option<Effect> {
             state.cmdline.active = true;
             state.cmdline.input = crate::app::input::LineEdit::new("/");
             state.cmdline.live = true;
+            state.cmdline.begin_history_navigation();
             state.search = SearchState::default();
             state.active_tab = Tab::Global;
             if !matches!(state.global.stack.last(), Some(GlobalView::Search { .. })) {
@@ -365,12 +382,14 @@ pub fn update(state: &mut AppState, action: Action) -> Option<Effect> {
             open_track_info(state, tracks, "no track selected")
         }
         Action::OpenCurrentTrackInfo => {
-            let tracks = state.player.current.clone().into_iter().collect();
+            let tracks = current_track_for_info(state).into_iter().collect();
             open_track_info(state, tracks, "nothing playing")
         }
         Action::RemoveFromQueue => remove_selected_from_queue(state),
         Action::QueueAddNext => queue_add(state, true),
         Action::QueueAddLast => queue_add(state, false),
+        Action::MoveQueueUp => move_selected_queue(state, true),
+        Action::MoveQueueDown => move_selected_queue(state, false),
         Action::GoToRelease => {
             let track = selected_track(state).or_else(|| state.player.current.clone());
             match track {
@@ -418,6 +437,7 @@ pub fn update(state: &mut AppState, action: Action) -> Option<Effect> {
             let had_tracks = !state.player.queue.is_empty();
             state.player.queue.clear();
             state.player.queue_pos = 0;
+            state.player.play_next_end = None;
             state.player.current = None;
             state.player.playing = false;
             state.player.paused = false;
@@ -440,6 +460,31 @@ pub fn update(state: &mut AppState, action: Action) -> Option<Effect> {
     }
 }
 
+/// Prefer the queue's current entry because it may have been enriched or
+/// replaced with a durable local track after streaming started. The player
+/// keeps its original lightweight entry while that stream is active.
+fn current_track_for_info(state: &AppState) -> Option<TrackItem> {
+    let current = state.player.current.as_ref()?;
+    let current_key = super::state::track_key(current);
+    let queued_at_position = state.player.queue.get(state.player.queue_pos);
+
+    queued_at_position
+        .filter(|queued| {
+            super::state::track_key(queued) == current_key
+                || queued.id == current.id
+                || current.is_fed_pending()
+        })
+        .or_else(|| {
+            state
+                .player
+                .queue
+                .iter()
+                .find(|queued| super::state::track_key(queued) == current_key)
+        })
+        .cloned()
+        .or_else(|| Some(current.clone()))
+}
+
 fn track_info_needs_fed_metadata(track: &TrackItem) -> bool {
     track.fed.is_some()
         && (track.featured_artists.is_empty()
@@ -860,6 +905,9 @@ fn set_track_scope_cursor(state: &mut AppState, scope: &TrackSelectionScope, val
         TrackSelectionScope::Queue => {
             state.queue_tab.cursor = value;
         }
+        TrackSelectionScope::SimilaritySearch => {
+            set_view_cursor(state, value);
+        }
         TrackSelectionScope::FedSearch => {
             let base = state.search.results.as_ref().map_or(0, |r| r.len())
                 + state.search.fed_artists.len();
@@ -907,6 +955,14 @@ fn current_track_list_context(state: &AppState) -> Option<(TrackSelectionScope,
                 _ => None,
             },
             GlobalView::Search { cursor } => {
+                if state.search.similarity_source.is_some() {
+                    let len = state.search.similarity_len();
+                    return (*cursor < len).then_some((
+                        TrackSelectionScope::SimilaritySearch,
+                        *cursor,
+                        len,
+                    ));
+                }
                 // Only the federated tracks section is selectable here.
                 let base = state.search.results.as_ref().map_or(0, |r| r.len())
                     + state.search.fed_artists.len();
@@ -999,6 +1055,20 @@ fn current_track_list(state: &AppState) -> Option<(TrackSelectionScope, usize, V
 }
 
 pub fn selected_tracks(state: &AppState) -> Vec<TrackItem> {
+    if state.active_tab == Tab::Global
+        && state.search.similarity_source.is_some()
+        && let Some(GlobalView::Search { cursor }) = state.global.stack.last()
+    {
+        let len = state.search.similarity_len();
+        let indices = state
+            .track_selection
+            .indices(&TrackSelectionScope::SimilaritySearch, len)
+            .unwrap_or_else(|| vec![(*cursor).min(len.saturating_sub(1))]);
+        return indices
+            .into_iter()
+            .filter_map(|index| state.search.similarity_track(index))
+            .collect();
+    }
     // Federated contexts produce queueable placeholders that behave like
     // regular tracks (queue, info, playback-on-demand).
     {
@@ -1030,6 +1100,68 @@ fn selected_queue_indices(state: &AppState) -> Vec<usize> {
         .unwrap_or_else(|| vec![state.queue_tab.cursor.min(state.player.queue.len() - 1)])
 }
 
+fn move_selected_queue(state: &mut AppState, up: bool) -> Option<Effect> {
+    let indices = selected_queue_indices(state);
+    let Some(&start) = indices.first() else {
+        state.status_message = Some("queue is empty".into());
+        return None;
+    };
+    let end = *indices.last().unwrap_or(&start);
+    let len = state.player.queue.len();
+    if (up && start == 0) || (!up && end + 1 >= len) {
+        state.status_message = Some(if up {
+            "selection is already at the top of the queue".into()
+        } else {
+            "selection is already at the bottom of the queue".into()
+        });
+        return None;
+    }
+
+    let old_current = state.player.queue_pos;
+    let new_current = if up {
+        let displaced = state.player.queue.remove(start - 1);
+        state.player.queue.insert(end, displaced);
+        if old_current == start - 1 {
+            end
+        } else if (start..=end).contains(&old_current) {
+            old_current - 1
+        } else {
+            old_current
+        }
+    } else {
+        let displaced = state.player.queue.remove(end + 1);
+        state.player.queue.insert(start, displaced);
+        if old_current == end + 1 {
+            start
+        } else if (start..=end).contains(&old_current) {
+            old_current + 1
+        } else {
+            old_current
+        }
+    };
+    let delta: isize = if up { -1 } else { 1 };
+    state.player.queue_pos = new_current;
+    state.queue_tab.cursor = (state.queue_tab.cursor as isize + delta) as usize;
+    if state
+        .track_selection
+        .is_active_for(&TrackSelectionScope::Queue)
+    {
+        state.track_selection.anchor = (state.track_selection.anchor as isize + delta) as usize;
+        state.track_selection.cursor = (state.track_selection.cursor as isize + delta) as usize;
+    }
+    // An explicit manual order supersedes both the temporary play-next block
+    // and a saved pre-shuffle order.
+    state.player.play_next_end = None;
+    state.player.original_order = None;
+    let restart_current = state.player.prefetched_pos.take().is_some();
+    state.status_message = Some(format!(
+        "moved {} track(s) {}",
+        indices.len(),
+        if up { "up" } else { "down" }
+    ));
+    Some(Effect::QueueOrderChanged { restart_current })
+}
+
 fn remove_selected_from_queue(state: &mut AppState) -> Option<Effect> {
     let indices = selected_queue_indices(state);
     if indices.is_empty() {
@@ -1081,6 +1213,10 @@ fn remove_queue_indices(state: &mut AppState, indices: &[usize]) -> QueueRemoval
         .iter()
         .filter(|index| **index < old_queue_pos)
         .count();
+    if let Some(end) = state.player.play_next_end {
+        let removed_before_end = unique.iter().filter(|index| **index < end).count();
+        state.player.play_next_end = Some(end.saturating_sub(removed_before_end));
+    }
     let was_loaded = state.player.playing;
     let was_paused = state.player.paused;
 
@@ -1107,6 +1243,7 @@ fn remove_queue_indices(state: &mut AppState, indices: &[usize]) -> QueueRemoval
         state.player.track_started_at = None;
         state.player.listen_id = None;
         state.queue_tab.cursor = state.queue_tab.cursor.min(state.player.queue.len() - 1);
+        normalize_play_next_block(&mut state.player);
         return QueueRemovalOutcome {
             restart_paused: was_loaded.then_some(was_paused),
             stop: false,
@@ -1134,6 +1271,7 @@ fn remove_queue_indices(state: &mut AppState, indices: &[usize]) -> QueueRemoval
             .cloned()
     });
     state.queue_tab.cursor = state.queue_tab.cursor.min(state.player.queue.len() - 1);
+    normalize_play_next_block(&mut state.player);
     QueueRemovalOutcome {
         restart_paused: None,
         stop: false,
@@ -1163,6 +1301,9 @@ pub fn selected_track(state: &AppState) -> Option<TrackItem> {
                 _ => None,
             },
             GlobalView::Search { cursor } => {
+                if state.search.similarity_source.is_some() {
+                    return state.search.similarity_track(*cursor);
+                }
                 let results = state.search.results.as_ref()?;
                 let offset = cursor.checked_sub(results.artists.len() + results.releases.len())?;
                 match results.tracks.get(offset) {
@@ -1267,7 +1408,7 @@ fn queue_add(state: &mut AppState, next: bool) -> Option<Effect> {
     if !tracks.is_empty() {
         let count = tracks.len();
         let title = tracks[0].title.clone();
-        enqueue_tracks(state, tracks, next);
+        let restart_current = enqueue_tracks(state, tracks, next);
         state.track_selection.clear();
         state.status_message = Some(if count == 1 && next {
             format!("queued next: {title}")
@@ -1278,7 +1419,7 @@ fn queue_add(state: &mut AppState, next: bool) -> Option<Effect> {
         } else {
             format!("queued: {count} tracks")
         });
-        return Some(Effect::PlaybackQueueChanged);
+        return Some(Effect::QueueOrderChanged { restart_current });
     }
     if let Some(id) = selected_release_id(state) {
         return Some(Effect::EnqueueRelease { id, next });
@@ -1372,19 +1513,22 @@ pub(crate) fn track_artist_refs(track: &TrackItem) -> Vec<crate::library::models
     refs
 }
 
-/// Insert tracks after the playing one (`next`) or at the end. Keeps the
-/// gapless prefetch index pointing at the same track if items shift.
-pub fn enqueue_tracks(state: &mut AppState, tracks: Vec<TrackItem>, next: bool) {
+/// Insert tracks into the stable "play next" block (`next`) or at the end.
+/// Returns whether a decoded gapless-next source became stale.
+pub fn enqueue_tracks(state: &mut AppState, tracks: Vec<TrackItem>, next: bool) -> bool {
     let tracks: Vec<_> = tracks
         .into_iter()
         .filter(|track| track_allowed_by_source_mode(state, track))
         .collect();
     let player = &mut state.player;
     if tracks.is_empty() {
-        return;
+        return false;
     }
     let insert_at = if next && !player.queue.is_empty() {
-        (player.queue_pos + 1).min(player.queue.len())
+        player
+            .play_next_end
+            .filter(|end| *end >= player.queue_pos.saturating_add(1) && *end <= player.queue.len())
+            .unwrap_or_else(|| (player.queue_pos + 1).min(player.queue.len()))
     } else if next {
         0
     } else {
@@ -1394,14 +1538,28 @@ pub fn enqueue_tracks(state: &mut AppState, tracks: Vec<TrackItem>, next: bool)
     for (offset, track) in tracks.into_iter().enumerate() {
         player.queue.insert(insert_at + offset, track);
     }
-    if let Some(prefetched) = &mut player.prefetched_pos
-        && insert_at <= *prefetched
-    {
-        *prefetched += count;
+    let restart_current = player
+        .prefetched_pos
+        .is_some_and(|prefetched| insert_at <= prefetched);
+    if restart_current {
+        player.prefetched_pos = None;
     }
     if insert_at <= player.queue_pos && player.current.is_some() {
         player.queue_pos += count;
     }
+    if next {
+        player.play_next_end = Some(insert_at + count);
+    }
+    restart_current
+}
+
+pub(super) fn normalize_play_next_block(player: &mut super::state::PlayerBar) {
+    if player
+        .play_next_end
+        .is_some_and(|end| end <= player.queue_pos || end > player.queue.len())
+    {
+        player.play_next_end = None;
+    }
 }
 
 /// Manual queue navigation (n / p); the tail is pre-shuffled when shuffle
@@ -1426,6 +1584,7 @@ fn queue_step(state: &mut AppState, direction: isize) -> Option<Effect> {
     } else {
         player.queue_pos = next as usize;
     }
+    normalize_play_next_block(player);
     Some(Effect::PlayCurrent)
 }
 
@@ -1464,9 +1623,11 @@ pub fn advance_after_finish(state: &mut AppState) -> Option<Effect> {
         repeat => {
             if player.queue_pos + 1 < player.queue.len() {
                 player.queue_pos += 1;
+                normalize_play_next_block(player);
                 Some(Effect::PlayCurrent)
             } else if repeat == super::state::RepeatMode::All {
                 player.queue_pos = 0;
+                player.play_next_end = None;
                 Some(Effect::PlayCurrent)
             } else {
                 player.playing = false;
@@ -1744,10 +1905,13 @@ fn move_selection(state: &mut AppState, dx: isize, dy: isize) {
             refresh_track_selection_cursor(state);
         }
         Some(GlobalView::Search { cursor }) => {
-            // Local results plus the federated section below them.
-            let total = (state.search.results.as_ref().map_or(0, |r| r.len())
-                + state.search.fed_artists.len()
-                + state.search.fed_tracks.len()) as isize;
+            let total = if state.search.similarity_source.is_some() {
+                state.search.similarity_len()
+            } else {
+                state.search.results.as_ref().map_or(0, |r| r.len())
+                    + state.search.fed_artists.len()
+                    + state.search.fed_tracks.len()
+            } as isize;
             if total == 0 {
                 return;
             }
@@ -1867,9 +2031,13 @@ fn current_view_len(state: &AppState) -> usize {
             _ => 0,
         },
         Some(GlobalView::Search { .. }) => {
-            state.search.results.as_ref().map_or(0, |r| r.len())
-                + state.search.fed_artists.len()
-                + state.search.fed_tracks.len()
+            if state.search.similarity_source.is_some() {
+                state.search.similarity_len()
+            } else {
+                state.search.results.as_ref().map_or(0, |r| r.len())
+                    + state.search.fed_artists.len()
+                    + state.search.fed_tracks.len()
+            }
         }
         Some(GlobalView::FedArtist { .. }) => fed_card_len(state),
         Some(GlobalView::FedRelease { index, .. }) => fed_card_release(state, *index)
@@ -2076,6 +2244,7 @@ fn select_current(state: &mut AppState) -> Option<Effect> {
             return None;
         }
         state.player.queue_pos = state.queue_tab.cursor.min(state.player.queue.len() - 1);
+        normalize_play_next_block(&mut state.player);
         return Some(Effect::PlayCurrent);
     }
     if state.active_tab != Tab::Global {
@@ -2158,31 +2327,47 @@ fn select_current(state: &mut AppState) -> Option<Effect> {
             },
             _ => Outcome::Nothing,
         },
-        Some(GlobalView::Search { cursor }) => match &state.search.results {
-            Some(results) => {
-                let artists = results.artists.len();
-                let releases = results.releases.len();
-                if cursor < artists {
-                    Outcome::Push(GlobalView::Artist {
-                        id: results.artists[cursor].id,
-                        cursor: 0,
-                    })
-                } else if cursor < artists + releases {
-                    Outcome::Push(GlobalView::Release {
-                        id: results.releases[cursor - artists].id,
-                        cursor: 0,
-                    })
-                } else if results.tracks.get(cursor - artists - releases).is_some() {
-                    Outcome::Play {
-                        tracks: results.tracks.clone(),
-                        start: cursor - artists - releases,
-                    }
+        Some(GlobalView::Search { cursor }) => {
+            if state.search.similarity_source.is_some() {
+                let tracks = (0..state.search.similarity_len())
+                    .filter_map(|index| state.search.similarity_track(index))
+                    .collect::<Vec<_>>();
+                if tracks.is_empty() {
+                    Outcome::Nothing
                 } else {
-                    fed_outcome(state, cursor - artists - releases - results.tracks.len())
+                    Outcome::Play {
+                        start: cursor.min(tracks.len() - 1),
+                        tracks,
+                    }
+                }
+            } else {
+                match &state.search.results {
+                    Some(results) => {
+                        let artists = results.artists.len();
+                        let releases = results.releases.len();
+                        if cursor < artists {
+                            Outcome::Push(GlobalView::Artist {
+                                id: results.artists[cursor].id,
+                                cursor: 0,
+                            })
+                        } else if cursor < artists + releases {
+                            Outcome::Push(GlobalView::Release {
+                                id: results.releases[cursor - artists].id,
+                                cursor: 0,
+                            })
+                        } else if results.tracks.get(cursor - artists - releases).is_some() {
+                            Outcome::Play {
+                                tracks: results.tracks.clone(),
+                                start: cursor - artists - releases,
+                            }
+                        } else {
+                            fed_outcome(state, cursor - artists - releases - results.tracks.len())
+                        }
+                    }
+                    None => fed_outcome(state, cursor),
                 }
             }
-            None => fed_outcome(state, cursor),
-        },
+        }
         Some(GlobalView::FedArtist { cursor }) => match &state.fed_artist_view {
             Some((_, Loadable::Ready(card))) => {
                 let release_indices = fed_artist_visible_release_indices(state, card);
@@ -2358,6 +2543,20 @@ pub(crate) fn selected_fed_tracks(state: &AppState) -> Vec<crate::federation::Fe
     if state.active_tab != Tab::Global {
         return Vec::new();
     }
+    if state.search.similarity_source.is_some()
+        && let Some(GlobalView::Search { cursor }) = state.global.stack.last()
+    {
+        let scope = TrackSelectionScope::SimilaritySearch;
+        let len = state.search.similarity_len();
+        let indices = state
+            .track_selection
+            .indices(&scope, len)
+            .unwrap_or_else(|| vec![(*cursor).min(len.saturating_sub(1))]);
+        return indices
+            .into_iter()
+            .filter_map(|index| state.search.similarity_fed_track(index).cloned())
+            .collect();
+    }
     // An active Shift-V range in a federated scope.
     if let Some(scope) = state.track_selection.scope.clone() {
         match scope {
@@ -2614,8 +2813,86 @@ fn fed_card_featured_artist_names(track: &crate::federation::FedCardTrack) -> Ve
 /// Enter on Settings: toggle switches, open text inputs, run
 /// one-shot operations. The heavy lifting happens in perform_effect().
 fn federation_select(state: &mut AppState) -> Option<Effect> {
-    use super::state::{FedInputField, FedRow, Popup, SettingsRow};
+    use super::state::{FedInputField, FedRow, Popup, SettingsRow, SimilarityRow};
     match settings_rows(state).get(state.settings_cursor).copied()? {
+        SettingsRow::MusicDirectory => {
+            if state.music_dir_changing {
+                state.status_message = Some("music directory change is already running".into());
+                return None;
+            }
+            state.popup = Some(Popup::FedInput {
+                field: FedInputField::MusicDirectory,
+                input: crate::app::input::LineEdit::new(
+                    state.music_dir.to_string_lossy().into_owned(),
+                ),
+            });
+            None
+        }
+        SettingsRow::Similarity(SimilarityRow::Toggle) => {
+            if !state.similarity.settings.enabled
+                && state.federation.settings.enabled
+                && !state.similarity.settings.federation_consent
+            {
+                state.popup = Some(Popup::SimilarityPrivacyConsent {
+                    enable_federation: false,
+                });
+                return None;
+            }
+            state.similarity.settings.enabled = !state.similarity.settings.enabled;
+            Some(Effect::SimilarityApplySettings)
+        }
+        SettingsRow::Similarity(SimilarityRow::Model) => {
+            let models = crate::similarity::MODELS;
+            let current = models
+                .iter()
+                .position(|model| model.id == state.similarity.settings.model)
+                .unwrap_or(0);
+            state.similarity.settings.model = models[(current + 1) % models.len()].id.to_string();
+            Some(Effect::SimilarityApplySettings)
+        }
+        SettingsRow::Similarity(SimilarityRow::Profile) => {
+            let profile = state.similarity.settings.profile.clone();
+            let text =
+                crate::similarity::profile_details(&profile, &state.similarity.settings.model)
+                    .unwrap_or_else(|| format!("Unknown preprocessing profile: {profile}"));
+            state.popup = Some(Popup::FedText {
+                title: format!("Preprocessing profile: {profile}"),
+                text,
+            });
+            None
+        }
+        SettingsRow::Similarity(SimilarityRow::MinimumScore) => {
+            state.popup = Some(Popup::FedInput {
+                field: FedInputField::SimilarityMinimumScore,
+                input: crate::app::input::LineEdit::new(format!(
+                    "{:.2}",
+                    state.similarity.settings.minimum_score
+                )),
+            });
+            None
+        }
+        SettingsRow::Similarity(SimilarityRow::MaxTracksPerArtist) => {
+            state.popup = Some(Popup::FedInput {
+                field: FedInputField::SimilarityMaxTracksPerArtist,
+                input: crate::app::input::LineEdit::new(
+                    state.similarity.settings.max_tracks_per_artist.to_string(),
+                ),
+            });
+            None
+        }
+        SettingsRow::Similarity(SimilarityRow::Workers) => {
+            state.popup = Some(Popup::FedInput {
+                field: FedInputField::SimilarityWorkers,
+                input: crate::app::input::LineEdit::new(
+                    state.similarity.settings.workers.to_string(),
+                ),
+            });
+            None
+        }
+        SettingsRow::Similarity(SimilarityRow::Clear) => {
+            state.popup = Some(Popup::ConfirmClearEmbeddings);
+            None
+        }
         SettingsRow::Federation(FedRow::Toggle) => {
             let settings = &mut state.federation.settings;
             if !settings.enabled && settings.network_id.trim().is_empty() {
@@ -2625,7 +2902,17 @@ fn federation_select(state: &mut AppState) -> Option<Effect> {
                 });
                 return None;
             }
-            settings.enabled = !settings.enabled;
+            let enabling = !settings.enabled;
+            settings.enabled = enabling;
+            if enabling
+                && state.similarity.settings.enabled
+                && !state.similarity.settings.federation_consent
+            {
+                state.popup = Some(Popup::SimilarityPrivacyConsent {
+                    enable_federation: true,
+                });
+                return None;
+            }
             Some(Effect::FedApplySettings)
         }
         SettingsRow::Federation(FedRow::NetworkId) => {
@@ -2789,6 +3076,7 @@ fn require_connected_devices_enabled(state: &mut AppState) -> bool {
 pub(super) fn on_new_queue(state: &mut AppState) {
     let player = &mut state.player;
     player.original_order = None;
+    player.play_next_end = None;
     if player.shuffle && !player.queue.is_empty() {
         player.original_order = Some(player.queue.iter().map(track_key).collect());
         shuffle_range(player, (player.queue_pos + 1).min(player.queue.len()));

src/app/update_tests.rs

@@ -457,6 +457,7 @@ fn local_mode_hides_pending_federation_tracks_from_playlists_and_playback() {
         active_tab: Tab::Playlists,
         ..AppState::default()
     };
+    state.global.filters.source_mode = crate::config::settings::LibrarySourceMode::Local;
     state.playlists.opened = Some(OpenedPlaylist { id: 7, cursor: 1 });
     state.playlist_views.insert(
         7,
@@ -512,6 +513,7 @@ fn network_modes_show_pending_federation_playlist_tracks() {
 #[test]
 fn local_mode_rejects_async_federation_queue_additions() {
     let mut state = AppState::default();
+    state.global.filters.source_mode = crate::config::settings::LibrarySourceMode::Local;
 
     enqueue_tracks(
         &mut state,
@@ -569,9 +571,15 @@ fn current_track_info_uses_now_playing_track() {
         active_tab: Tab::Queue,
         ..AppState::default()
     };
-    state.player.queue = vec![test_track(1), test_track(2)];
+    let mut complete = test_track(2);
+    complete.audio_format = Some("flac".into());
+    complete.audio_bitrate = Some(921);
+    state.player.queue = vec![test_track(1), complete];
+    state.player.queue_pos = 1;
     state.queue_tab.cursor = 0;
-    state.player.current = Some(test_track(2));
+    let mut lightweight = test_track(2);
+    lightweight.file_path.clear();
+    state.player.current = Some(lightweight);
 
     assert_eq!(update(&mut state, Action::OpenCurrentTrackInfo), None);
     match &state.popup {
@@ -580,6 +588,9 @@ fn current_track_info_uses_now_playing_track() {
                 tracks.iter().map(|track| track.id).collect::<Vec<_>>(),
                 vec![2]
             );
+            assert_eq!(tracks[0].file_path, "/s/2");
+            assert_eq!(tracks[0].audio_format.as_deref(), Some("flac"));
+            assert_eq!(tracks[0].audio_bitrate, Some(921));
         }
         other => panic!("expected track info popup, got {other:?}"),
     }
@@ -732,13 +743,78 @@ fn artist_top_track_selection_queues_all_selected_tracks() {
     update(&mut state, Action::MoveDown);
     assert_eq!(
         update(&mut state, Action::QueueAddLast),
-        Some(Effect::PlaybackQueueChanged),
+        Some(Effect::QueueOrderChanged {
+            restart_current: false,
+        }),
     );
     let queued: Vec<i64> = state.player.queue.iter().map(|track| track.id).collect();
     assert_eq!(queued, vec![1, 2]);
     assert!(!state.track_selection.is_active());
 }
 
+#[test]
+fn sequential_queue_next_additions_keep_their_order_as_one_block() {
+    let mut state = AppState::default();
+    state.player.queue = (10..=13).map(test_track).collect();
+    state.player.queue_pos = 0;
+    state.player.current = Some(test_track(10));
+
+    assert!(!enqueue_tracks(&mut state, vec![test_track(1)], true));
+    assert!(!enqueue_tracks(&mut state, vec![test_track(2)], true));
+    assert!(!enqueue_tracks(&mut state, vec![test_track(3)], true));
+
+    assert_eq!(
+        state
+            .player
+            .queue
+            .iter()
+            .map(|track| track.id)
+            .collect::<Vec<_>>(),
+        vec![10, 1, 2, 3, 11, 12, 13]
+    );
+    assert_eq!(state.player.play_next_end, Some(4));
+}
+
+#[test]
+fn queue_selection_moves_as_a_group_and_preserves_current_track() {
+    let mut state = AppState {
+        active_tab: Tab::Queue,
+        ..AppState::default()
+    };
+    state.player.queue = (1..=5).map(test_track).collect();
+    state.player.queue_pos = 0;
+    state.player.current = Some(test_track(1));
+    state.queue_tab.cursor = 2;
+    state.track_selection.start(TrackSelectionScope::Queue, 2);
+    state
+        .track_selection
+        .set_cursor(TrackSelectionScope::Queue, 3);
+
+    assert_eq!(
+        update(&mut state, Action::MoveQueueUp),
+        Some(Effect::QueueOrderChanged {
+            restart_current: false,
+        })
+    );
+    assert_eq!(
+        state
+            .player
+            .queue
+            .iter()
+            .map(|track| track.id)
+            .collect::<Vec<_>>(),
+        vec![1, 3, 4, 2, 5]
+    );
+    assert_eq!(state.player.queue_pos, 0);
+    assert_eq!(state.queue_tab.cursor, 1);
+    assert_eq!(
+        state
+            .track_selection
+            .indices(&TrackSelectionScope::Queue, 5),
+        Some(vec![1, 2])
+    );
+}
+
 #[test]
 fn removing_current_queue_track_requests_paused_restart() {
     let mut state = AppState {

src/config/default_keymap.toml

@@ -63,6 +63,16 @@ command = "QueueAddNext"
 key_sequence = "shift-a"
 command = "QueueAddLast"
 
+[[keymaps]]
+key_sequence = "alt-k"
+command = "MoveQueueUp"
+context = "queue"
+
+[[keymaps]]
+key_sequence = "alt-j"
+command = "MoveQueueDown"
+context = "queue"
+
 [[keymaps]]
 key_sequence = "shift-c"
 command = "OpenConnectedDevices"

src/config/settings.rs

@@ -1,5 +1,6 @@
 use anyhow::{Context as _, Result};
 use serde::{Deserialize, Serialize};
+use std::path::PathBuf;
 
 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
@@ -44,12 +45,61 @@ pub struct LibraryFilters {
     pub source_mode: LibrarySourceMode,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct SimilaritySettings {
+    /// Local embedding/search master switch. Network participation follows
+    /// federation and additionally requires the explicit privacy consent.
+    #[serde(default)]
+    pub enabled: bool,
+    #[serde(default = "default_similarity_model")]
+    pub model: String,
+    #[serde(default = "default_similarity_profile")]
+    pub profile: String,
+    #[serde(default = "default_similarity_workers")]
+    pub workers: usize,
+    /// Requester-side cosine score floor. This is search policy, not part of
+    /// the embedding profile, so changing it never invalidates vectors.
+    #[serde(default = "default_similarity_minimum_score")]
+    pub minimum_score: f32,
+    /// Requester-side diversity cap applied independently to local and
+    /// federated candidates.
+    #[serde(default = "default_similarity_max_tracks_per_artist")]
+    pub max_tracks_per_artist: usize,
+    #[serde(default)]
+    pub federation_consent: bool,
+    /// Exact fingerprint of the last fully usable profile. Keeping this
+    /// separate from the selected target lets an old index serve searches
+    /// while a newly selected model/profile is being calculated.
+    #[serde(default)]
+    pub active_profile: Option<String>,
+}
+
+impl Default for SimilaritySettings {
+    fn default() -> Self {
+        Self {
+            enabled: false,
+            model: default_similarity_model(),
+            profile: default_similarity_profile(),
+            workers: default_similarity_workers(),
+            minimum_score: default_similarity_minimum_score(),
+            max_tracks_per_artist: default_similarity_max_tracks_per_artist(),
+            federation_consent: false,
+            active_profile: None,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct AppSettings {
     #[serde(default = "default_volume")]
     pub volume: u8,
     #[serde(default)]
     pub library: LibraryFilters,
+    /// Root used for music materialized from federation peers.
+    #[serde(default = "default_music_dir")]
+    pub music_dir: PathBuf,
+    #[serde(default)]
+    pub similarity: SimilaritySettings,
 }
 
 impl Default for AppSettings {
@@ -57,6 +107,8 @@ impl Default for AppSettings {
         Self {
             volume: default_volume(),
             library: LibraryFilters::default(),
+            music_dir: default_music_dir(),
+            similarity: SimilaritySettings::default(),
         }
     }
 }
@@ -64,6 +116,21 @@ impl Default for AppSettings {
 impl AppSettings {
     pub fn normalized(mut self) -> Self {
         self.volume = self.volume.min(100);
+        if self.music_dir.as_os_str().is_empty() {
+            self.music_dir = default_music_dir();
+        }
+        if self.similarity.model.trim().is_empty() {
+            self.similarity.model = default_similarity_model();
+        }
+        if self.similarity.profile.trim().is_empty() {
+            self.similarity.profile = default_similarity_profile();
+        }
+        self.similarity.workers = self.similarity.workers.clamp(1, 16);
+        if !self.similarity.minimum_score.is_finite() {
+            self.similarity.minimum_score = default_similarity_minimum_score();
+        }
+        self.similarity.minimum_score = self.similarity.minimum_score.clamp(0.0, 1.0);
+        self.similarity.max_tracks_per_artist = self.similarity.max_tracks_per_artist.clamp(1, 50);
         self
     }
 }
@@ -72,6 +139,36 @@ fn default_volume() -> u8 {
     80
 }
 
+fn default_similarity_model() -> String {
+    "discogs-effnet-bsdynamic-1".to_string()
+}
+
+fn default_similarity_profile() -> String {
+    "furumi-full-track-v1".to_string()
+}
+
+fn default_similarity_workers() -> usize {
+    std::thread::available_parallelism()
+        .map(|count| (count.get() / 2).clamp(1, 4))
+        .unwrap_or(1)
+}
+
+fn default_similarity_minimum_score() -> f32 {
+    0.70
+}
+
+fn default_similarity_max_tracks_per_artist() -> usize {
+    5
+}
+
+/// The historical permanent-download location, kept as the default for
+/// backward compatibility with existing installations.
+pub fn default_music_dir() -> PathBuf {
+    crate::config::project_dirs()
+        .map(|dirs| dirs.data_dir().join("federation-media"))
+        .unwrap_or_else(|| PathBuf::from("federation-media"))
+}
+
 pub fn load() -> (AppSettings, Option<String>) {
     let Some(path) = settings_path() else {
         return (AppSettings::default(), None);
@@ -129,5 +226,22 @@ hide_featured_only = true
         assert_eq!(settings.volume, 100);
         assert!(settings.library.hide_featured_only);
         assert_eq!(settings.library.source_mode, LibrarySourceMode::Global);
+        assert_eq!(settings.music_dir, default_music_dir());
+        assert_eq!(settings.similarity.minimum_score, 0.70);
+        assert_eq!(settings.similarity.max_tracks_per_artist, 5);
+    }
+
+    #[test]
+    fn similarity_search_policy_is_normalized_without_changing_the_profile() {
+        let mut settings = AppSettings::default();
+        let profile = settings.similarity.profile.clone();
+        settings.similarity.minimum_score = f32::NAN;
+        settings.similarity.max_tracks_per_artist = 0;
+
+        let settings = settings.normalized();
+
+        assert_eq!(settings.similarity.minimum_score, 0.70);
+        assert_eq!(settings.similarity.max_tracks_per_artist, 1);
+        assert_eq!(settings.similarity.profile, profile);
     }
 }

src/federation/capabilities.rs

@@ -170,6 +170,8 @@ mod tests {
             "music_dht",
             "catalog",
             "audio",
+            "similarity",
+            "similarity_dht",
             "device_sync",
             "jam",
         ] {

src/federation/mod.rs

@@ -15,6 +15,7 @@
 mod audio;
 mod capabilities;
 pub mod catalog;
+mod similarity;
 
 use std::collections::{HashMap, VecDeque};
 use std::path::{Path, PathBuf};
@@ -24,6 +25,8 @@ use std::sync::atomic::{AtomicI64, Ordering};
 use std::time::Duration;
 
 use anyhow::{Context, Result};
+use music_dht::similarity_dht::SimilarityDht;
+use music_dht::similarity_lsh::SIMILARITY_DHT_ALPN;
 use music_dht::{
     ByteStream, ByteStreamConnectionStats, EndpointId, ItemKind, ItemSpec, LibraryItem,
     MusicDhtConfig, MusicDhtService, NetworkId, PeerTicket, PublishStats, RendezvousConfig,
@@ -39,6 +42,7 @@ use crate::library::models::{ArtistRef, TrackItem};
 pub use audio::{AUDIO_ALPN, DownloadProgress, StreamingStart, TrackMetadata};
 pub use capabilities::ProtocolVersions;
 pub use catalog::{CATALOG_ALPN, FedAppearsOn, FedArtistCard, FedCardTrack, FedRelease};
+pub use similarity::SIMILARITY_ALPN;
 
 /// How often the published library is re-synchronized with the local index.
 const SYNC_INTERVAL: Duration = Duration::from_secs(60);
@@ -334,6 +338,27 @@ pub struct FedSearchResults {
     pub tracks: Vec<FedTrack>,
 }
 
+#[derive(Debug, Clone)]
+pub struct ScoredFedTrack {
+    pub track: FedTrack,
+    pub score: f32,
+    pub embedding_signature: Option<[u8; music_dht::similarity::SIMILARITY_SIGNATURE_BYTES]>,
+}
+
+#[derive(Debug, Clone, Default, PartialEq, Eq)]
+pub struct SimilaritySearchStats {
+    pub tracks: usize,
+    pub artists: usize,
+    pub peers_queried: usize,
+    pub elapsed_ms: u64,
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct FedSimilaritySearchResults {
+    pub tracks: Vec<ScoredFedTrack>,
+    pub stats: SimilaritySearchStats,
+}
+
 /// A track found through federated search.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct FedTrack {
@@ -411,6 +436,7 @@ pub struct NetworkLibrarySource {
 
 struct Running {
     service: Arc<MusicDhtService>,
+    similarity_dht: Arc<SimilarityDht>,
     network_name: String,
     network_id: NetworkId,
     tasks: Vec<tokio::task::JoinHandle<()>>,
@@ -420,9 +446,12 @@ pub struct Federation {
     library: Arc<Library>,
     devices: Arc<crate::devices::DeviceSync>,
     jam: Arc<crate::jam::JamManager>,
+    similarity: Arc<crate::similarity::Manager>,
     data_dir: PathBuf,
     cache_dir: PathBuf,
-    media_dir: PathBuf,
+    media_dir: std::sync::Mutex<PathBuf>,
+    /// Serializes permanent downloads/card writes with a directory change.
+    media_change: tokio::sync::Mutex<()>,
     metadata_cache: std::sync::Mutex<std::collections::HashMap<String, CachedTrackMetadata>>,
     settings: std::sync::Mutex<FedSettings>,
     running: tokio::sync::Mutex<Option<Running>>,
@@ -524,6 +553,8 @@ impl Federation {
         library: Arc<Library>,
         devices: Arc<crate::devices::DeviceSync>,
         jam: Arc<crate::jam::JamManager>,
+        similarity: Arc<crate::similarity::Manager>,
+        media_dir: PathBuf,
     ) -> Arc<Self> {
         let dirs = crate::config::project_dirs();
         let data_dir = dirs
@@ -534,10 +565,6 @@ impl Federation {
             .as_ref()
             .map(|d| d.cache_dir().join("fedcache"))
             .unwrap_or_else(|| PathBuf::from("fedcache"));
-        let media_dir = dirs
-            .as_ref()
-            .map(|d| d.data_dir().join("federation-media"))
-            .unwrap_or_else(|| PathBuf::from("federation-media"));
         let initial_error = [&data_dir, &cache_dir, &media_dir]
             .into_iter()
             .find_map(|dir| {
@@ -545,13 +572,16 @@ impl Federation {
                     .err()
                     .map(|err| format!("cannot create {}: {err}", dir.display()))
             });
+        let media_dir = std::fs::canonicalize(&media_dir).unwrap_or(media_dir);
         Arc::new(Self {
             library,
             devices,
             jam,
+            similarity,
             data_dir,
             cache_dir,
-            media_dir,
+            media_dir: std::sync::Mutex::new(media_dir),
+            media_change: tokio::sync::Mutex::new(()),
             metadata_cache: std::sync::Mutex::new(Default::default()),
             settings: std::sync::Mutex::new(load_settings()),
             running: tokio::sync::Mutex::new(None),
@@ -566,6 +596,40 @@ impl Federation {
         lock(&self.settings).clone()
     }
 
+    pub fn media_dir(&self) -> PathBuf {
+        lock(&self.media_dir).clone()
+    }
+
+    /// Switches the permanent-download root while excluding concurrent
+    /// downloads. Validation runs again here because permissions may have
+    /// changed after the confirmation popup was shown.
+    pub async fn change_media_dir(
+        self: &Arc<Self>,
+        requested: PathBuf,
+        move_existing: bool,
+    ) -> Result<crate::library::MusicRelocationStats> {
+        let _guard = self.media_change.lock().await;
+        let old = self.media_dir();
+        let library = Arc::clone(&self.library);
+        let requested_for_task = requested.clone();
+        let (path, stats) = tokio::task::spawn_blocking(move || -> Result<_> {
+            let path = Library::validate_music_directory(&requested_for_task)?;
+            if path == std::fs::canonicalize(&old).unwrap_or(old.clone()) {
+                return Ok((path, crate::library::MusicRelocationStats::default()));
+            }
+            let stats = if move_existing && old.exists() {
+                library.relocate_managed_music(&old, &path)?
+            } else {
+                crate::library::MusicRelocationStats::default()
+            };
+            Ok((path, stats))
+        })
+        .await
+        .context("music directory task failed")??;
+        *lock(&self.media_dir) = path;
+        Ok(stats)
+    }
+
     pub async fn create_jam(&self) -> Result<String> {
         let service = {
             let running = self.running.lock().await;
@@ -657,10 +721,15 @@ impl Federation {
             .stream_protocol(AUDIO_ALPN)
             // ...and browse each other's per-artist catalogs over this one.
             .stream_protocol(CATALOG_ALPN)
+            // Anonymous, bounded direct embedding queries have their own
+            // versioned contract and survive catalog-schema upgrades.
+            .schema_independent_stream_protocol(SIMILARITY_ALPN)
             // Personal-device sync (likes, playlists, trusted devices).
             .stream_protocol(crate::devices::SYNC_ALPN)
             // Capability-scoped shared playback control.
             .stream_protocol(crate::jam::JAM_ALPN)
+            // Signed LSH summaries form their own upgrade-safe DHT overlay.
+            .schema_independent_stream_protocol(SIMILARITY_DHT_ALPN)
             // Informational application/protocol versions.
             .schema_independent_stream_protocol(capabilities::CAPABILITIES_ALPN)
             .build()
@@ -675,6 +744,25 @@ impl Federation {
             "federation started"
         );
 
+        let similarity_dht = SimilarityDht::open(
+            Arc::clone(&service),
+            self.data_dir.join("similarity-routing.sqlite3"),
+        )
+        .await
+        .map_err(|err| anyhow::anyhow!("failed to start the similarity DHT: {err}"))?;
+        let similarity_dht_acceptor = service
+            .stream_acceptor(SIMILARITY_DHT_ALPN)
+            .map_err(|err| anyhow::anyhow!("failed to take similarity DHT acceptor: {err}"))?;
+        let similarity_dht_serve_task =
+            tokio::spawn(Arc::clone(&similarity_dht).serve(similarity_dht_acceptor));
+        let similarity_dht_maintenance_task =
+            tokio::spawn(Arc::clone(&similarity_dht).maintenance());
+        let similarity_dht_sync_task = tokio::spawn(similarity_route_sync_loop(
+            Arc::clone(&similarity_dht),
+            Arc::clone(&self.similarity),
+            Arc::clone(&self.library),
+        ));
+
         // Drain DHT events into the log; the channel is bounded.
         let event_task = tokio::spawn(async move {
             while let Some(event) = events.recv().await {
@@ -711,6 +799,15 @@ impl Federation {
             service.endpoint_id(),
             Arc::clone(&self.transport_stats),
         ));
+        let similarity_acceptor = service
+            .stream_acceptor(SIMILARITY_ALPN)
+            .map_err(|err| anyhow::anyhow!("failed to take the similarity acceptor: {err}"))?;
+        let similarity_task = tokio::spawn(similarity::serve_peers(
+            similarity_acceptor,
+            Arc::clone(&self.similarity),
+            service.endpoint_id(),
+            Arc::clone(&self.transport_stats),
+        ));
         let sync_acceptor = service
             .stream_acceptor(crate::devices::SYNC_ALPN)
             .map_err(|err| anyhow::anyhow!("failed to take the device-sync acceptor: {err}"))?;
@@ -746,6 +843,7 @@ impl Federation {
 
         *guard = Some(Running {
             service,
+            similarity_dht,
             network_name,
             network_id,
             tasks: vec![
@@ -753,12 +851,16 @@ impl Federation {
                 sync_task,
                 audio_task,
                 catalog_task,
+                similarity_task,
                 device_sync_task,
                 device_tick_task,
                 jam_serve_task,
                 jam_poll_task,
                 capabilities_serve_task,
                 capabilities_probe_task,
+                similarity_dht_serve_task,
+                similarity_dht_maintenance_task,
+                similarity_dht_sync_task,
             ],
         });
         self.set_error(None);
@@ -783,6 +885,20 @@ impl Federation {
             .context("federation is not running")
     }
 
+    async fn similarity_services(&self) -> Result<(Arc<MusicDhtService>, Arc<SimilarityDht>)> {
+        self.running
+            .lock()
+            .await
+            .as_ref()
+            .map(|running| {
+                (
+                    Arc::clone(&running.service),
+                    Arc::clone(&running.similarity_dht),
+                )
+            })
+            .context("federation is not running")
+    }
+
     fn ensure_connected_devices_enabled(&self) -> Result<()> {
         let settings = self.settings();
         anyhow::ensure!(
@@ -1112,6 +1228,30 @@ impl Federation {
         Ok(FedSearchResults { artists, tracks })
     }
 
+    /// Bounded fan-out to known peers using the exact model/profile
+    /// fingerprint carried with the query. No DHT records are written.
+    pub async fn search_similar(
+        &self,
+        query: crate::similarity::QueryVector,
+        limit: usize,
+    ) -> Result<FedSimilaritySearchResults> {
+        anyhow::ensure!(
+            self.similarity.network_allowed(),
+            "similarity federation has no consent"
+        );
+        let (service, similarity_dht) = self.similarity_services().await?;
+        let settings = self.similarity.settings();
+        similarity::search(
+            service,
+            similarity_dht,
+            query,
+            limit,
+            settings.minimum_score,
+            Arc::clone(&self.transport_stats),
+        )
+        .await
+    }
+
     /// Resolves a share-link content id to one playable federated track.
     ///
     /// Resolution order: the in-session metadata cache, the DHT content key,
@@ -1403,29 +1543,21 @@ impl Federation {
         Ok(peer.to_string())
     }
 
-    /// Directory for streamed (never library-imported) card artwork.
-    fn art_cache_dir(&self) -> PathBuf {
-        self.cache_dir.join("art")
-    }
-
     /// Returns a cached-or-streamed image for the card: the artist image
     /// (`release: None`) or a release cover. Peers are tried in order until
-    /// one answers with an image; the result lands in the art cache and its
-    /// local path is returned.
+    /// one answers with an image; the result is stored beside the artist or
+    /// release in the permanent music tree and its local path is returned.
     pub async fn card_image(
         &self,
         owners: &[String],
         artist: &str,
         release: Option<&str>,
     ) -> Option<String> {
-        let dir = self.art_cache_dir();
+        let _guard = self.media_change.lock().await;
+        let dir = music_art_dir(&self.media_dir(), artist, release);
         let stem = match release {
-            Some(release) => format!(
-                "cover-{}-{}",
-                sanitize_file_stem(artist),
-                sanitize_file_stem(release)
-            ),
-            None => format!("artist-{}", sanitize_file_stem(artist)),
+            Some(_) => "cover".to_string(),
+            None => "artist".to_string(),
         };
         // Reuse a previously streamed copy of any known image type.
         for extension in ["jpg", "png", "webp", "gif", "bmp"] {
@@ -1489,7 +1621,7 @@ impl Federation {
         F: FnMut(DownloadProgress) + Send,
     {
         let save = self.settings().save_on_listen;
-        self.fetch_playable_with_progress(fed, save, false, progress, None)
+        self.fetch_playable_with_progress(fed, save, save, progress, None)
             .await
     }
 
@@ -1504,7 +1636,7 @@ impl Federation {
         S: FnMut(StreamingStart) + Send,
     {
         let save = self.settings().save_on_listen;
-        self.fetch_playable_with_progress(fed, save, false, progress, Some(&mut stream_start))
+        self.fetch_playable_with_progress(fed, save, save, progress, Some(&mut stream_start))
             .await
     }
 
@@ -1558,6 +1690,11 @@ impl Federation {
     where
         F: FnMut(DownloadProgress) + Send,
     {
+        let _media_guard = if save {
+            Some(self.media_change.lock().await)
+        } else {
+            None
+        };
         let mut fed = fed.clone();
         let mut tried_content_lookup = false;
 
@@ -1636,8 +1773,10 @@ impl Federation {
                 }
                 Err(_) => anyhow::bail!("malformed owner id '{}'", fed.owner),
             };
+            let media_dir;
             let dir = if save {
-                &self.media_dir
+                media_dir = music_release_dir(&self.media_dir(), &fed);
+                &media_dir
             } else {
                 &self.cache_dir
             };
@@ -1698,8 +1837,14 @@ impl Federation {
                     }
                     // Same for the cover: the peer's library cover wins over an
                     // embedded picture; embedded art stays as the fallback.
-                    if import_cover.is_some() {
-                        import.cover = import_cover;
+                    if let Some((bytes, extension)) = &import_cover {
+                        match save_release_cover(&import_path, bytes, extension) {
+                            Ok(()) => import.cover = None,
+                            Err(err) => {
+                                tracing::warn!(%err, "saving the release cover beside its music failed");
+                                import.cover = import_cover;
+                            }
+                        }
                     }
                     let (track_id, _) = crate::library::import::upsert_track(&library, &import)?;
                     // A like that referenced the federated track moves onto the
@@ -1711,7 +1856,13 @@ impl Federation {
                     // created (or still image-less) main artist.
                     if let (Some((bytes, extension)), Some(artist_name)) =
                         (&artist_image, import.artists.first())
-                        && let Err(err) = save_artist_image(&library, artist_name, bytes, extension)
+                        && let Err(err) = save_artist_image(
+                            &library,
+                            artist_name,
+                            import_path.parent().and_then(Path::parent),
+                            bytes,
+                            extension,
+                        )
                     {
                         tracing::warn!(%err, "saving the artist image failed");
                     }
@@ -1938,20 +2089,18 @@ impl Federation {
     }
 }
 
-/// Writes a received artist image into the covers directory and attaches it
-/// to the artist unless one is already set.
+/// Writes a received artist image into the artist's music directory and
+/// attaches it to the artist unless one is already set.
 fn save_artist_image(
     library: &Library,
     artist_name: &str,
+    artist_dir: Option<&Path>,
     bytes: &[u8],
     extension: &str,
 ) -> Result<()> {
-    let covers_dir = library.covers_dir();
-    std::fs::create_dir_all(covers_dir)?;
-    let path = covers_dir.join(format!(
-        "artist-{}.{extension}",
-        sanitize_file_stem(artist_name)
-    ));
+    let artist_dir = artist_dir.context("downloaded track has no artist directory")?;
+    std::fs::create_dir_all(artist_dir)?;
+    let path = artist_dir.join(format!("artist.{extension}"));
     // Write only if the artist actually lacks an image, to avoid litter.
     if library.artist_image_missing(artist_name)? {
         std::fs::write(&path, bytes)?;
@@ -1960,6 +2109,16 @@ fn save_artist_image(
     Ok(())
 }
 
+fn save_release_cover(audio_path: &Path, bytes: &[u8], extension: &str) -> Result<()> {
+    let directory = audio_path
+        .parent()
+        .context("downloaded track has no release directory")?;
+    std::fs::create_dir_all(directory)?;
+    let path = directory.join(format!("cover.{extension}"));
+    std::fs::write(&path, bytes).with_context(|| format!("writing {}", path.display()))?;
+    Ok(())
+}
+
 /// Overlays the peer-supplied metadata onto tag-derived import data. Every
 /// non-empty peer field wins; file tags only fill the gaps.
 fn apply_remote_metadata(import: &mut crate::library::import::TrackImport, meta: &TrackMetadata) {
@@ -2479,6 +2638,77 @@ fn sort_fed_appearances(appearances: &mut [FedAppearsOn]) {
     });
 }
 
+async fn similarity_route_sync_loop(
+    routing: Arc<SimilarityDht>,
+    similarity: Arc<crate::similarity::Manager>,
+    library: Arc<Library>,
+) {
+    let mut interval = tokio::time::interval(SYNC_INTERVAL);
+    interval.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);
+    let mut published_marker: Option<(String, blake3::Hash)> = None;
+    loop {
+        interval.tick().await;
+        if !similarity.network_allowed() {
+            if published_marker.take().is_some() {
+                routing.clear_local_signatures();
+                tracing::info!("local similarity DHT publication disabled");
+            }
+            continue;
+        }
+        let status = similarity.status();
+        let Some(profile_id) = status.active_profile else {
+            continue;
+        };
+        if status.phase != crate::similarity::Phase::Ready {
+            continue;
+        }
+        let library = Arc::clone(&library);
+        let profile_for_task = profile_id.clone();
+        let loaded = tokio::task::spawn_blocking(move || {
+            let signatures = library.similarity_routing_signatures(&profile_for_task)?;
+            let mut hasher = blake3::Hasher::new();
+            for signature in &signatures {
+                hasher.update(signature);
+            }
+            Ok::<_, anyhow::Error>((signatures, hasher.finalize()))
+        })
+        .await;
+        let (signatures, fingerprint) = match loaded {
+            Ok(Ok(loaded)) => loaded,
+            Ok(Err(error)) => {
+                tracing::warn!(%error, %profile_id, "similarity routing signatures unavailable");
+                continue;
+            }
+            Err(error) => {
+                tracing::warn!(%error, "similarity routing signature task failed");
+                continue;
+            }
+        };
+        let marker = (profile_id.clone(), fingerprint);
+        if published_marker.as_ref() == Some(&marker) {
+            continue;
+        }
+        match routing
+            .sync_local_signatures(profile_id.clone(), signatures)
+            .await
+        {
+            Ok(stats) => {
+                tracing::info!(
+                    profile = %profile_id,
+                    records = stats.records,
+                    keys = stats.keys,
+                    remote_nodes = stats.remote_nodes,
+                    "local similarity DHT index synchronized"
+                );
+                published_marker = Some(marker);
+            }
+            Err(error) => {
+                tracing::warn!(%error, %profile_id, "similarity DHT synchronization failed");
+            }
+        }
+    }
+}
+
 async fn stop_running(running: Option<Running>) {
     let Some(running) = running else { return };
     for task in &running.tasks {
@@ -2546,29 +2776,43 @@ fn collect_specs(library: &Library) -> Result<Vec<ItemSpec>> {
     Ok(specs)
 }
 
-fn sanitize_file_stem(value: &str) -> String {
-    let cleaned: String = value
-        .chars()
-        .map(|c| match c {
-            '/' | '\\' | ':' | '*' | '?' | '"' | '<' | '>' | '|' => '_',
-            c if c.is_control() => '_',
-            c => c,
-        })
-        .collect();
-    let trimmed = cleaned.trim().trim_matches('.');
-    let mut stem: String = trimmed.chars().take(120).collect();
-    if stem.is_empty() {
-        stem.push_str("track");
+fn music_artist_dir(root: &Path, artist: &str) -> PathBuf {
+    let artist = if artist.trim().is_empty() {
+        "Unknown Artist"
+    } else {
+        artist
+    };
+    root.join(crate::library::storage_name(artist, "Unknown Artist"))
+}
+
+fn music_art_dir(root: &Path, artist: &str, release: Option<&str>) -> PathBuf {
+    let artist_dir = music_artist_dir(root, artist);
+    match release.filter(|release| !release.trim().is_empty()) {
+        Some(release) => artist_dir.join(crate::library::storage_name(release, "Unknown Release")),
+        None => artist_dir,
     }
-    stem
+}
+
+fn music_release_dir(root: &Path, fed: &FedTrack) -> PathBuf {
+    let artist = fed
+        .artist_names
+        .first()
+        .map(String::as_str)
+        .unwrap_or("Unknown Artist");
+    let release = fed
+        .release_title
+        .as_deref()
+        .filter(|release| !release.trim().is_empty())
+        .unwrap_or("Unknown Release");
+    music_art_dir(root, artist, Some(release))
 }
 
 fn download_stem(fed: &FedTrack) -> String {
     let artists = fed.artist_line();
     if artists.is_empty() {
-        sanitize_file_stem(&fed.title)
+        crate::library::storage_name(&fed.title, "track")
     } else {
-        sanitize_file_stem(&format!("{artists} - {}", fed.title))
+        crate::library::storage_name(&format!("{artists} - {}", fed.title), "track")
     }
 }
 

src/federation/similarity.rs

@@ -0,0 +1,367 @@
+//! Furumi policy and local-index adapter for the shared similarity protocol.
+//!
+//! `music_dht::similarity` owns the versioned wire contract and framing. This
+//! module owns application policy: consent, peer fan-out, local index access,
+//! result conversion, deduplication, and ranking limits.
+
+use std::collections::HashSet;
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+
+use anyhow::{Context as _, Result};
+use futures_util::stream::{self, StreamExt as _};
+use music_dht::similarity::{self as wire, SimilarityHit, SimilarityRequest, SimilarityResponse};
+use music_dht::similarity_dht::SimilarityDht;
+use music_dht::{
+    ByteStream, EndpointId, ItemId, ItemKind, MusicDhtService, PeerTicket, StreamAcceptor,
+};
+
+use crate::federation::{
+    FedSimilaritySearchResults, FedTrack, ScoredFedTrack, SimilaritySearchStats, TransportStats,
+};
+use crate::similarity::{Manager, QueryVector};
+
+pub use music_dht::similarity::SIMILARITY_ALPN;
+
+const INITIAL_QUERY_PEERS: usize = 16;
+const MAX_QUERY_PEERS: usize = 48;
+const QUERY_CONCURRENCY: usize = 8;
+const QUERY_TIMEOUT: Duration = Duration::from_secs(5);
+const ROUTING_TIMEOUT: Duration = Duration::from_secs(5);
+const MAX_NEAR_DUPLICATE_SIGNATURE_DISTANCE: u32 = 8;
+
+pub async fn serve_peers(
+    mut acceptor: StreamAcceptor,
+    similarity: Arc<Manager>,
+    own: EndpointId,
+    transport: Arc<TransportStats>,
+) {
+    while let Some(stream) = acceptor.accept().await {
+        let similarity = Arc::clone(&similarity);
+        let transport = Arc::clone(&transport);
+        tokio::spawn(async move {
+            let peer = stream.peer_id;
+            if let Err(err) = serve_one(stream, similarity, own, transport).await {
+                tracing::warn!(peer = %peer, "similarity request failed: {err:#}");
+            }
+        });
+    }
+}
+
+async fn serve_one(
+    mut stream: ByteStream,
+    similarity: Arc<Manager>,
+    own: EndpointId,
+    transport: Arc<TransportStats>,
+) -> Result<()> {
+    super::record_stream_transport(&transport, "similarity", "inbound", "open", &stream);
+    let request = wire::read_request(&mut stream).await?;
+    let response = if !similarity.network_allowed() {
+        SimilarityResponse::refused("similarity federation is disabled or has no privacy consent")?
+    } else {
+        let profile = request.profile_id;
+        let vector = request.vector;
+        let limit = request.limit;
+        let matches = tokio::task::spawn_blocking(move || {
+            similarity.search_vector_for_peer(&profile, &vector, limit)
+        })
+        .await
+        .context("local similarity task failed")
+        .and_then(|result| result);
+        match matches {
+            Ok(matches) => {
+                let hits = matches
+                    .into_iter()
+                    .filter_map(|found| {
+                        let track = found.track;
+                        let hit = SimilarityHit {
+                            score: found.score,
+                            item_id: super::audio::hex_encode(
+                                ItemId::derive(
+                                    &own,
+                                    ItemKind::Track,
+                                    &format!("track:{}", track.id),
+                                )
+                                .as_bytes(),
+                            ),
+                            title: track.title,
+                            artist_names: track
+                                .artists
+                                .into_iter()
+                                .map(|artist| artist.name)
+                                .collect(),
+                            featured_artist_names: track
+                                .featured_artists
+                                .into_iter()
+                                .map(|artist| artist.name)
+                                .collect(),
+                            year: track.release_year,
+                            duration_seconds: Some(track.duration_seconds.round() as i64),
+                            content_id: track.content_id,
+                            release_title: Some(track.release_title),
+                            track_number: track.track_number,
+                            disc_number: track.disc_number,
+                            embedding_signature: Some(found.embedding_signature),
+                        };
+                        match hit.validate() {
+                            Ok(()) => Some(hit),
+                            Err(err) => {
+                                tracing::debug!(%err, "invalid local similarity metadata skipped");
+                                None
+                            }
+                        }
+                    })
+                    .collect();
+                SimilarityResponse::success(hits)?
+            }
+            Err(err) => {
+                SimilarityResponse::refused(format!("similarity query is unavailable: {err:#}"))?
+            }
+        }
+    };
+    wire::write_response(&mut stream, &response).await?;
+    stream.send.finish()?;
+    let _ = stream.send.stopped().await;
+    super::record_stream_transport(&transport, "similarity", "inbound", "done", &stream);
+    Ok(())
+}
+
+pub async fn search(
+    service: Arc<MusicDhtService>,
+    routing: Arc<SimilarityDht>,
+    query: QueryVector,
+    limit: usize,
+    minimum_score: f32,
+    transport: Arc<TransportStats>,
+) -> Result<FedSimilaritySearchResults> {
+    let started = Instant::now();
+    let own = service.endpoint_id();
+    let routed = match tokio::time::timeout(
+        ROUTING_TIMEOUT,
+        routing.find_peers(&query.profile_id, &query.vector, MAX_QUERY_PEERS),
+    )
+    .await
+    {
+        Ok(Ok(peers)) => peers,
+        Err(_) => {
+            tracing::debug!("similarity DHT lookup timed out; using known peers");
+            Vec::new()
+        }
+        Ok(Err(error)) => {
+            tracing::debug!(%error, "similarity DHT lookup unavailable; using known peers");
+            Vec::new()
+        }
+    };
+    let mut seen = HashSet::new();
+    let mut peers: Vec<QueryPeer> = routed
+        .into_iter()
+        .filter_map(|ticket| {
+            let owner = ticket.endpoint_id();
+            (owner != own && seen.insert(owner)).then_some(QueryPeer {
+                owner,
+                ticket: Some(ticket),
+            })
+        })
+        .collect();
+    for peer in service
+        .connected_peers()
+        .into_iter()
+        .chain(service.known_peers().into_iter().map(|peer| peer.peer_id))
+    {
+        if peer != own && seen.insert(peer) {
+            peers.push(QueryPeer {
+                owner: peer,
+                ticket: None,
+            });
+        }
+        if peers.len() >= MAX_QUERY_PEERS {
+            break;
+        }
+    }
+    let query_signature = wire::embedding_signature(&query.vector)?;
+    let request = Arc::new(SimilarityRequest::new(
+        query.profile_id,
+        query.vector,
+        limit.clamp(1, wire::MAX_SIMILARITY_RESULTS),
+    )?);
+
+    let mut hits = Vec::new();
+    let initial = peers.len().min(INITIAL_QUERY_PEERS);
+    let responses = query_peers(
+        Arc::clone(&service),
+        &peers[..initial],
+        Arc::clone(&request),
+        Arc::clone(&transport),
+    )
+    .await;
+    let mut successful = 0usize;
+    let mut peers_queried = initial;
+    for response in responses {
+        match response {
+            Ok(peer_hits) => {
+                successful += 1;
+                hits.extend(peer_hits);
+            }
+            Err(err) => tracing::debug!(%err, "similarity peer query skipped"),
+        }
+    }
+    if initial < peers.len() && (hits.len() < limit || successful < initial.min(4)) {
+        peers_queried = peers.len();
+        for response in query_peers(
+            Arc::clone(&service),
+            &peers[initial..],
+            Arc::clone(&request),
+            Arc::clone(&transport),
+        )
+        .await
+        {
+            match response {
+                Ok(peer_hits) => hits.extend(peer_hits),
+                Err(err) => tracing::debug!(%err, "fallback similarity peer query skipped"),
+            }
+        }
+    }
+    hits.sort_by(|left, right| right.1.total_cmp(&left.1));
+    let mut dedup = HashSet::new();
+    let mut embedding_signatures = vec![query_signature];
+    let mut tracks = Vec::new();
+    for (track, score, embedding_signature) in hits {
+        if score < minimum_score {
+            break;
+        }
+        if query
+            .source_content_id
+            .as_deref()
+            .is_some_and(|source| track.content_id.as_deref() == Some(source))
+        {
+            continue;
+        }
+        let key = track
+            .content_id
+            .clone()
+            .unwrap_or_else(|| format!("{}:{}", track.owner, track.item_id));
+        if !dedup.insert(key) {
+            continue;
+        }
+        if embedding_signature.is_some_and(|candidate| {
+            embedding_signatures.iter().any(|existing| {
+                wire::signature_distance(&candidate, existing)
+                    <= MAX_NEAR_DUPLICATE_SIGNATURE_DISTANCE
+            })
+        }) {
+            continue;
+        }
+        if let Some(signature) = embedding_signature {
+            embedding_signatures.push(signature);
+        }
+        tracks.push(ScoredFedTrack {
+            track,
+            score,
+            embedding_signature,
+        });
+        if tracks.len() >= limit.min(wire::MAX_SIMILARITY_RESULTS) {
+            break;
+        }
+    }
+    let artists = tracks
+        .iter()
+        .filter_map(|hit| hit.track.artist_names.first())
+        .map(|name| music_dht::normalize_name(name))
+        .filter(|name| !name.is_empty())
+        .collect::<HashSet<_>>()
+        .len();
+    let elapsed_ms = started.elapsed().as_millis().min(u128::from(u64::MAX)) as u64;
+    Ok(FedSimilaritySearchResults {
+        stats: SimilaritySearchStats {
+            tracks: tracks.len(),
+            artists,
+            peers_queried,
+            elapsed_ms,
+        },
+        tracks,
+    })
+}
+
+type PeerHits = Vec<(
+    FedTrack,
+    f32,
+    Option<[u8; wire::SIMILARITY_SIGNATURE_BYTES]>,
+)>;
+
+#[derive(Clone)]
+struct QueryPeer {
+    owner: EndpointId,
+    ticket: Option<PeerTicket>,
+}
+
+async fn query_peers(
+    service: Arc<MusicDhtService>,
+    peers: &[QueryPeer],
+    request: Arc<SimilarityRequest>,
+    transport: Arc<TransportStats>,
+) -> Vec<Result<PeerHits>> {
+    stream::iter(peers.iter().cloned().map(|peer| {
+        let service = Arc::clone(&service);
+        let request = Arc::clone(&request);
+        let transport = Arc::clone(&transport);
+        async move {
+            tokio::time::timeout(
+                QUERY_TIMEOUT,
+                query_peer(service, peer, &request, transport),
+            )
+            .await
+            .map_err(|_| anyhow::anyhow!("similarity peer timed out"))?
+        }
+    }))
+    .buffer_unordered(QUERY_CONCURRENCY)
+    .collect()
+    .await
+}
+
+async fn query_peer(
+    service: Arc<MusicDhtService>,
+    peer: QueryPeer,
+    request: &SimilarityRequest,
+    transport: Arc<TransportStats>,
+) -> Result<PeerHits> {
+    let owner = peer.owner;
+    let mut stream = match peer.ticket {
+        Some(ticket) => service.open_stream_to(&ticket, SIMILARITY_ALPN).await,
+        None => service.open_stream(owner, SIMILARITY_ALPN).await,
+    }
+    .map_err(|err| anyhow::anyhow!("cannot reach similarity peer: {err}"))?;
+    super::record_stream_transport(&transport, "similarity", "outbound", "open", &stream);
+    let response = wire::exchange(&mut stream, request).await?;
+    super::record_stream_transport(&transport, "similarity", "outbound", "done", &stream);
+    anyhow::ensure!(
+        response.ok,
+        "peer refused similarity query: {}",
+        response.error.unwrap_or_default()
+    );
+    Ok(response
+        .hits
+        .into_iter()
+        .map(|hit| {
+            let score = hit.score;
+            let embedding_signature = hit.embedding_signature;
+            (
+                FedTrack {
+                    item_id: hit.item_id,
+                    owner: owner.to_string(),
+                    own: false,
+                    title: hit.title,
+                    artist_names: hit.artist_names,
+                    featured_artist_names: hit.featured_artist_names,
+                    year: hit.year,
+                    duration_seconds: hit.duration_seconds,
+                    content_id: hit.content_id,
+                    release_title: hit.release_title,
+                    track_number: hit.track_number,
+                    disc_number: hit.disc_number,
+                },
+                score,
+                embedding_signature,
+            )
+        })
+        .collect())
+}

src/library/mod.rs

@@ -11,6 +11,7 @@ pub mod import;
 pub mod models;
 
 use std::collections::{HashMap, HashSet};
+use std::io::Write as _;
 use std::path::{Path, PathBuf};
 use std::sync::Mutex;
 
@@ -192,6 +193,27 @@ CREATE INDEX IF NOT EXISTS idx_network_artist_cache_kind
     ON network_artist_cache(source_kind, seen_at_ms);
 CREATE INDEX IF NOT EXISTS idx_network_artist_cache_artist
     ON network_artist_cache(artist_key);
+CREATE TABLE IF NOT EXISTS similarity_profiles (
+    profile_id       TEXT PRIMARY KEY,
+    model_id         TEXT NOT NULL,
+    model_version    TEXT NOT NULL,
+    model_sha256     TEXT NOT NULL,
+    preprocessing    TEXT NOT NULL,
+    dimensions       INTEGER NOT NULL,
+    created_at_ms    INTEGER NOT NULL
+);
+CREATE TABLE IF NOT EXISTS track_embeddings (
+    track_id          INTEGER NOT NULL REFERENCES tracks(id) ON DELETE CASCADE,
+    profile_id        TEXT NOT NULL REFERENCES similarity_profiles(profile_id) ON DELETE CASCADE,
+    dimensions        INTEGER NOT NULL,
+    vector            BLOB NOT NULL,
+    routing_signature BLOB,
+    source_content_id TEXT,
+    computed_at_ms    INTEGER NOT NULL,
+    PRIMARY KEY (track_id, profile_id)
+);
+CREATE INDEX IF NOT EXISTS idx_track_embeddings_profile
+    ON track_embeddings(profile_id, track_id);
 ";
 
 /// The SELECT column list every TrackItem row is built from; artist lists
@@ -270,6 +292,32 @@ pub struct NetworkArtistImageRequest {
     pub name: String,
 }
 
+/// Minimal durable-track row used by the background embedding pipeline.
+#[derive(Debug, Clone)]
+pub struct SimilarityTrack {
+    pub id: i64,
+    pub title: String,
+    pub file_path: String,
+    pub content_id: Option<String>,
+    pub duration_seconds: f64,
+}
+
+/// One validated vector loaded from SQLite for the in-memory exact index.
+#[derive(Debug, Clone)]
+pub struct StoredEmbedding {
+    pub track_id: i64,
+    pub vector: Vec<f32>,
+    pub artist_key: String,
+}
+
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+pub struct SimilarityStorageStats {
+    pub total_tracks: usize,
+    pub embedded_tracks: usize,
+    pub stored_vectors: usize,
+    pub stored_bytes: u64,
+}
+
 pub struct Library {
     conn: Mutex<Connection>,
     db_path: PathBuf,
@@ -288,6 +336,12 @@ pub struct LocalLibraryStats {
     pub database_bytes: u64,
 }
 
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+pub struct MusicRelocationStats {
+    pub tracks: usize,
+    pub images: usize,
+}
+
 impl LocalLibraryStats {
     pub fn total_bytes(&self) -> u64 {
         self.audio_bytes
@@ -330,6 +384,261 @@ impl Library {
         &self.covers_dir
     }
 
+    /// Verifies that `path` can actually be used for durable downloads. The
+    /// returned path is absolute/canonical, so the persisted setting does not
+    /// later depend on Furumi's working directory.
+    pub fn validate_music_directory(path: &Path) -> Result<PathBuf> {
+        anyhow::ensure!(!path.as_os_str().is_empty(), "music directory is empty");
+        std::fs::create_dir_all(path)
+            .with_context(|| format!("creating music directory {}", path.display()))?;
+        let path = std::fs::canonicalize(path)
+            .with_context(|| format!("resolving music directory {}", path.display()))?;
+        anyhow::ensure!(path.is_dir(), "{} is not a directory", path.display());
+
+        let unique = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .map(|duration| duration.as_nanos())
+            .unwrap_or(0);
+        let probe = path.join(format!(
+            ".furumi-write-test-{}-{unique}",
+            std::process::id()
+        ));
+        let result = (|| -> Result<()> {
+            let mut file = std::fs::OpenOptions::new()
+                .write(true)
+                .create_new(true)
+                .open(&probe)
+                .with_context(|| format!("no write access to {}", path.display()))?;
+            file.write_all(b"furumi")?;
+            file.sync_all()?;
+            Ok(())
+        })();
+        let _ = std::fs::remove_file(&probe);
+        result?;
+        Ok(path)
+    }
+
+    /// Copies Furumi-managed audio and its managed artwork into a portable
+    /// `Artist/Release` tree, atomically switches SQLite paths, then removes
+    /// the old copies. User-imported audio outside `old_root` is untouched.
+    pub fn relocate_managed_music(
+        &self,
+        old_root: &Path,
+        new_root: &Path,
+    ) -> Result<MusicRelocationStats> {
+        let new_root = Self::validate_music_directory(new_root)?;
+        let old_root = std::fs::canonicalize(old_root)
+            .with_context(|| format!("resolving old music directory {}", old_root.display()))?;
+        anyhow::ensure!(
+            old_root != new_root,
+            "the new music directory is the current directory"
+        );
+        anyhow::ensure!(
+            !old_root.starts_with(&new_root) && !new_root.starts_with(&old_root),
+            "choose a directory outside the current music directory"
+        );
+
+        #[derive(Debug)]
+        struct Row {
+            track_id: i64,
+            track_path: String,
+            release_id: i64,
+            release_title: String,
+            cover_path: Option<String>,
+            artist_id: Option<i64>,
+            artist_name: String,
+            image_path: Option<String>,
+        }
+
+        let rows = {
+            let conn = self.lock();
+            let mut statement = conn.prepare(
+                "SELECT t.id, t.file_path, r.id, r.title, r.cover_path,
+                        a.id, COALESCE(a.name, 'Unknown Artist'), a.image_path
+                 FROM tracks t
+                 JOIN releases r ON r.id = t.release_id
+                 LEFT JOIN track_artists ta
+                   ON ta.track_id = t.id AND ta.role = 'main' AND ta.position = 0
+                 LEFT JOIN artists a ON a.id = ta.artist_id
+                 ORDER BY t.id",
+            )?;
+            statement
+                .query_map([], |row| {
+                    Ok(Row {
+                        track_id: row.get(0)?,
+                        track_path: row.get(1)?,
+                        release_id: row.get(2)?,
+                        release_title: row.get(3)?,
+                        cover_path: row.get(4)?,
+                        artist_id: row.get(5)?,
+                        artist_name: row.get(6)?,
+                        image_path: row.get(7)?,
+                    })
+                })?
+                .collect::<rusqlite::Result<Vec<_>>>()?
+        };
+
+        #[derive(Debug, Clone)]
+        struct CopyOp {
+            source: PathBuf,
+            destination: PathBuf,
+        }
+        let managed_art =
+            |path: &Path| path.starts_with(&old_root) || path.starts_with(&self.covers_dir);
+        let mut reserved = HashSet::<PathBuf>::new();
+        let mut copies = Vec::<CopyOp>::new();
+        let mut track_updates = Vec::<(i64, String, String)>::new();
+        let mut release_updates = HashMap::<i64, (String, String)>::new();
+        let mut artist_updates = HashMap::<i64, (String, String)>::new();
+
+        for row in rows {
+            let source = PathBuf::from(&row.track_path);
+            let source = std::fs::canonicalize(&source).unwrap_or(source);
+            if !source.is_file() || !source.starts_with(&old_root) {
+                continue;
+            }
+            let artist_dir = new_root.join(storage_name(&row.artist_name, "Unknown Artist"));
+            let release_dir = artist_dir.join(storage_name(&row.release_title, "Unknown Release"));
+            let filename = source
+                .file_name()
+                .filter(|name| !name.is_empty())
+                .unwrap_or_else(|| std::ffi::OsStr::new("track"));
+            let destination =
+                unique_destination(release_dir.join(filename), row.track_id, &mut reserved);
+            copies.push(CopyOp {
+                source: source.clone(),
+                destination: destination.clone(),
+            });
+            track_updates.push((
+                row.track_id,
+                row.track_path,
+                destination.to_string_lossy().into_owned(),
+            ));
+
+            if let Some(cover) = row.cover_path {
+                let cover_source = PathBuf::from(&cover);
+                let cover_source = std::fs::canonicalize(&cover_source).unwrap_or(cover_source);
+                if cover_source.is_file()
+                    && managed_art(&cover_source)
+                    && !release_updates.contains_key(&row.release_id)
+                {
+                    let extension = cover_source.extension().unwrap_or_default();
+                    let mut destination = release_dir.join("cover");
+                    destination.set_extension(extension);
+                    let destination =
+                        unique_destination(destination, row.release_id, &mut reserved);
+                    copies.push(CopyOp {
+                        source: cover_source,
+                        destination: destination.clone(),
+                    });
+                    release_updates.insert(
+                        row.release_id,
+                        (cover, destination.to_string_lossy().into_owned()),
+                    );
+                }
+            }
+
+            if let (Some(artist_id), Some(image)) = (row.artist_id, row.image_path) {
+                let image_source = PathBuf::from(&image);
+                let image_source = std::fs::canonicalize(&image_source).unwrap_or(image_source);
+                if image_source.is_file()
+                    && managed_art(&image_source)
+                    && !artist_updates.contains_key(&artist_id)
+                {
+                    let extension = image_source.extension().unwrap_or_default();
+                    let mut destination = artist_dir.join("artist");
+                    destination.set_extension(extension);
+                    let destination = unique_destination(destination, artist_id, &mut reserved);
+                    copies.push(CopyOp {
+                        source: image_source,
+                        destination: destination.clone(),
+                    });
+                    artist_updates.insert(
+                        artist_id,
+                        (image, destination.to_string_lossy().into_owned()),
+                    );
+                }
+            }
+        }
+
+        let mut created = Vec::<PathBuf>::new();
+        let copy_result = (|| -> Result<()> {
+            for op in &copies {
+                let parent = op
+                    .destination
+                    .parent()
+                    .context("music destination has no parent")?;
+                std::fs::create_dir_all(parent)?;
+                copy_file_exclusive(&op.source, &op.destination)?;
+                created.push(op.destination.clone());
+            }
+            Ok(())
+        })();
+        if let Err(error) = copy_result {
+            for path in created.iter().rev() {
+                let _ = std::fs::remove_file(path);
+            }
+            return Err(error.context("copying the existing music library"));
+        }
+
+        let database_result = (|| -> Result<()> {
+            let mut conn = self.lock();
+            let transaction = conn.transaction()?;
+            for (id, old, new) in &track_updates {
+                anyhow::ensure!(
+                    transaction.execute(
+                        "UPDATE tracks SET file_path = ?3 WHERE id = ?1 AND file_path = ?2",
+                        params![id, old, new],
+                    )? == 1,
+                    "track {id} changed while the music library was moving"
+                );
+            }
+            for (id, (old, new)) in &release_updates {
+                anyhow::ensure!(
+                    transaction.execute(
+                        "UPDATE releases SET cover_path = ?3 WHERE id = ?1 AND cover_path = ?2",
+                        params![id, old, new],
+                    )? == 1,
+                    "release {id} changed while the music library was moving"
+                );
+            }
+            for (id, (old, new)) in &artist_updates {
+                anyhow::ensure!(
+                    transaction.execute(
+                        "UPDATE artists SET image_path = ?3 WHERE id = ?1 AND image_path = ?2",
+                        params![id, old, new],
+                    )? == 1,
+                    "artist {id} changed while the music library was moving"
+                );
+            }
+            transaction.commit()?;
+            Ok(())
+        })();
+        if let Err(error) = database_result {
+            for path in created.iter().rev() {
+                let _ = std::fs::remove_file(path);
+            }
+            return Err(error.context("updating music paths in the library"));
+        }
+
+        let mut removed = HashSet::new();
+        for op in &copies {
+            if removed.insert(op.source.clone())
+                && let Err(error) = std::fs::remove_file(&op.source)
+            {
+                // The committed destination is authoritative. A failed old
+                // delete only leaves a recoverable duplicate.
+                tracing::warn!(path = %op.source.display(), %error, "old music copy was not removed");
+            }
+        }
+        remove_empty_directories(&old_root);
+
+        Ok(MusicRelocationStats {
+            tracks: track_updates.len(),
+            images: release_updates.len() + artist_updates.len(),
+        })
+    }
+
     pub fn local_stats(&self) -> Result<LocalLibraryStats> {
         let (artist_count, release_count, track_count, audio_bytes, tracks_without_size) = {
             let conn = self.lock();
@@ -1171,6 +1480,254 @@ impl Library {
         Ok(tracks.pop())
     }
 
+    // -----------------------------------------------------------------
+    // Similarity embeddings. SQLite is the canonical store; callers build
+    // replaceable in-memory indexes from these rows.
+    // -----------------------------------------------------------------
+
+    pub fn ensure_similarity_profile(
+        &self,
+        profile_id: &str,
+        model_id: &str,
+        model_version: &str,
+        model_sha256: &str,
+        preprocessing: &str,
+        dimensions: usize,
+    ) -> Result<()> {
+        let conn = self.lock();
+        conn.execute(
+            "INSERT INTO similarity_profiles (
+                 profile_id, model_id, model_version, model_sha256,
+                 preprocessing, dimensions, created_at_ms
+             ) VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7)
+             ON CONFLICT(profile_id) DO NOTHING",
+            params![
+                profile_id,
+                model_id,
+                model_version,
+                model_sha256,
+                preprocessing,
+                dimensions as i64,
+                now_ms_i64(),
+            ],
+        )?;
+        Ok(())
+    }
+
+    pub fn pending_similarity_tracks(&self, profile_id: &str) -> Result<Vec<SimilarityTrack>> {
+        let conn = self.lock();
+        let mut statement = conn.prepare(
+            "SELECT t.id, t.title, t.file_path, t.content_id, t.duration_seconds
+             FROM tracks t
+             WHERE NOT EXISTS (
+                 SELECT 1 FROM track_embeddings e
+                 WHERE e.track_id = t.id
+                   AND e.profile_id = ?1
+                   AND e.source_content_id IS t.content_id
+             )
+             ORDER BY t.id",
+        )?;
+        Ok(statement
+            .query_map([profile_id], |row| {
+                Ok(SimilarityTrack {
+                    id: row.get(0)?,
+                    title: row.get(1)?,
+                    file_path: row.get(2)?,
+                    content_id: row.get(3)?,
+                    duration_seconds: row.get(4)?,
+                })
+            })?
+            .collect::<rusqlite::Result<Vec<_>>>()?)
+    }
+
+    pub fn store_similarity_embedding(
+        &self,
+        track: &SimilarityTrack,
+        profile_id: &str,
+        vector: &[f32],
+    ) -> Result<()> {
+        anyhow::ensure!(!vector.is_empty(), "embedding vector is empty");
+        anyhow::ensure!(
+            vector.iter().all(|value| value.is_finite()),
+            "embedding contains a non-finite value"
+        );
+        let bytes = embedding_to_bytes(vector);
+        let routing_signature = music_dht::similarity_lsh::routing_signature(vector)?;
+        let conn = self.lock();
+        conn.execute(
+            "INSERT INTO track_embeddings (
+                 track_id, profile_id, dimensions, vector, routing_signature,
+                 source_content_id, computed_at_ms
+             ) VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7)
+             ON CONFLICT(track_id, profile_id) DO UPDATE SET
+                 dimensions = excluded.dimensions,
+                 vector = excluded.vector,
+                 routing_signature = excluded.routing_signature,
+                 source_content_id = excluded.source_content_id,
+                 computed_at_ms = excluded.computed_at_ms",
+            params![
+                track.id,
+                profile_id,
+                vector.len() as i64,
+                bytes,
+                routing_signature.as_slice(),
+                track.content_id.as_deref(),
+                now_ms_i64(),
+            ],
+        )?;
+        Ok(())
+    }
+
+    pub fn similarity_embedding(
+        &self,
+        track_id: i64,
+        profile_id: &str,
+    ) -> Result<Option<Vec<f32>>> {
+        let conn = self.lock();
+        let row = conn
+            .query_row(
+                "SELECT e.dimensions, e.vector
+                 FROM track_embeddings e
+                 JOIN tracks t ON t.id = e.track_id
+                 WHERE e.track_id = ?1
+                   AND e.profile_id = ?2
+                   AND e.source_content_id IS t.content_id",
+                params![track_id, profile_id],
+                |row| Ok((row.get::<_, i64>(0)?, row.get::<_, Vec<u8>>(1)?)),
+            )
+            .optional()?;
+        row.map(|(dimensions, bytes)| embedding_from_bytes(dimensions, &bytes))
+            .transpose()
+    }
+
+    pub fn load_similarity_index(&self, profile_id: &str) -> Result<Vec<StoredEmbedding>> {
+        let conn = self.lock();
+        let mut statement = conn.prepare(
+            "SELECT e.track_id, e.dimensions, e.vector,
+                    COALESCE((
+                        SELECT norm(a.name)
+                        FROM track_artists ta
+                        JOIN artists a ON a.id = ta.artist_id
+                        WHERE ta.track_id = e.track_id AND ta.role = 'main'
+                        ORDER BY ta.position LIMIT 1
+                    ), '')
+             FROM track_embeddings e
+             JOIN tracks t ON t.id = e.track_id
+             WHERE e.profile_id = ?1
+               AND e.source_content_id IS t.content_id
+             ORDER BY e.track_id",
+        )?;
+        let rows = statement.query_map([profile_id], |row| {
+            Ok((
+                row.get::<_, i64>(0)?,
+                row.get::<_, i64>(1)?,
+                row.get::<_, Vec<u8>>(2)?,
+                row.get::<_, String>(3)?,
+            ))
+        })?;
+        let mut embeddings = Vec::new();
+        for row in rows {
+            let (track_id, dimensions, bytes, artist_key) = row?;
+            embeddings.push(StoredEmbedding {
+                track_id,
+                vector: embedding_from_bytes(dimensions, &bytes)?,
+                artist_key,
+            });
+        }
+        Ok(embeddings)
+    }
+
+    /// Loads the compact DHT-routing signatures for every current local
+    /// embedding. Rows created before similarity routing existed are
+    /// backfilled in place from their durable vectors.
+    pub fn similarity_routing_signatures(&self, profile_id: &str) -> Result<Vec<[u8; 32]>> {
+        let mut conn = self.lock();
+        let transaction = conn.transaction()?;
+        let missing = {
+            let mut statement = transaction.prepare(
+                "SELECT e.track_id, e.dimensions, e.vector
+             FROM track_embeddings e
+             JOIN tracks t ON t.id = e.track_id
+             WHERE e.profile_id = ?1
+               AND e.source_content_id IS t.content_id
+               AND (e.routing_signature IS NULL OR length(e.routing_signature) != 32)
+             ORDER BY e.track_id",
+            )?;
+            statement
+                .query_map([profile_id], |row| {
+                    Ok((
+                        row.get::<_, i64>(0)?,
+                        row.get::<_, i64>(1)?,
+                        row.get::<_, Vec<u8>>(2)?,
+                    ))
+                })?
+                .collect::<rusqlite::Result<Vec<_>>>()?
+        };
+        for (track_id, dimensions, vector_bytes) in missing {
+            let vector = embedding_from_bytes(dimensions, &vector_bytes)?;
+            let signature = music_dht::similarity_lsh::routing_signature(&vector)?;
+            transaction.execute(
+                "UPDATE track_embeddings
+                 SET routing_signature = ?3
+                 WHERE track_id = ?1 AND profile_id = ?2",
+                params![track_id, profile_id, signature.as_slice()],
+            )?;
+        }
+        transaction.commit()?;
+
+        let mut statement = conn.prepare(
+            "SELECT e.routing_signature
+             FROM track_embeddings e
+             JOIN tracks t ON t.id = e.track_id
+             WHERE e.profile_id = ?1
+               AND e.source_content_id IS t.content_id
+             ORDER BY e.track_id",
+        )?;
+        let stored = statement
+            .query_map([profile_id], |row| row.get::<_, Vec<u8>>(0))?
+            .collect::<rusqlite::Result<Vec<_>>>()?;
+        let signatures = stored
+            .into_iter()
+            .map(|signature| {
+                <[u8; 32]>::try_from(signature)
+                    .map_err(|_| anyhow::anyhow!("invalid similarity routing signature length"))
+            })
+            .collect::<Result<Vec<_>>>()?;
+        Ok(signatures)
+    }
+
+    pub fn similarity_storage_stats(&self, profile_id: &str) -> Result<SimilarityStorageStats> {
+        let conn = self.lock();
+        let total_tracks = conn.query_row("SELECT COUNT(*) FROM tracks", [], |row| {
+            row.get::<_, i64>(0)
+        })?;
+        let embedded_tracks = conn.query_row(
+            "SELECT COUNT(*)
+             FROM track_embeddings e JOIN tracks t ON t.id = e.track_id
+             WHERE e.profile_id = ?1 AND e.source_content_id IS t.content_id",
+            [profile_id],
+            |row| row.get::<_, i64>(0),
+        )?;
+        let (stored_vectors, stored_bytes) = conn.query_row(
+            "SELECT COUNT(*), COALESCE(SUM(length(vector)), 0) FROM track_embeddings",
+            [],
+            |row| Ok((row.get::<_, i64>(0)?, row.get::<_, i64>(1)?)),
+        )?;
+        Ok(SimilarityStorageStats {
+            total_tracks: total_tracks.max(0) as usize,
+            embedded_tracks: embedded_tracks.max(0) as usize,
+            stored_vectors: stored_vectors.max(0) as usize,
+            stored_bytes: stored_bytes.max(0) as u64,
+        })
+    }
+
+    pub fn clear_similarity_embeddings(&self) -> Result<()> {
+        let conn = self.lock();
+        conn.execute("DELETE FROM track_embeddings", [])?;
+        conn.execute("DELETE FROM similarity_profiles", [])?;
+        Ok(())
+    }
+
     // -----------------------------------------------------------------
     // Playlists & likes
     // -----------------------------------------------------------------
@@ -2498,6 +3055,96 @@ impl Library {
     }
 }
 
+pub(crate) fn storage_name(value: &str, fallback: &str) -> String {
+    let cleaned: String = value
+        .chars()
+        .map(|character| match character {
+            '/' | '\\' | ':' | '*' | '?' | '"' | '<' | '>' | '|' => '_',
+            character if character.is_control() => '_',
+            character => character,
+        })
+        .collect();
+    let cleaned = cleaned.trim().trim_matches('.');
+    let mut shortened: String = cleaned.chars().take(120).collect();
+    if shortened.is_empty() {
+        return fallback.to_string();
+    }
+    let windows_base = shortened
+        .split('.')
+        .next()
+        .unwrap_or_default()
+        .to_ascii_uppercase();
+    let windows_reserved = matches!(windows_base.as_str(), "CON" | "PRN" | "AUX" | "NUL")
+        || windows_base
+            .strip_prefix("COM")
+            .or_else(|| windows_base.strip_prefix("LPT"))
+            .is_some_and(|number| number.len() == 1 && matches!(number.as_bytes()[0], b'1'..=b'9'));
+    if windows_reserved {
+        shortened.insert(0, '_');
+    }
+    shortened
+}
+
+fn unique_destination(requested: PathBuf, id: i64, reserved: &mut HashSet<PathBuf>) -> PathBuf {
+    if !requested.exists() && reserved.insert(requested.clone()) {
+        return requested;
+    }
+    let stem = requested
+        .file_stem()
+        .unwrap_or_else(|| std::ffi::OsStr::new("file"))
+        .to_string_lossy();
+    let extension = requested.extension().map(|value| value.to_os_string());
+    let mut candidate = requested.with_file_name(format!("{stem}-{id}"));
+    if let Some(extension) = extension {
+        candidate.set_extension(extension);
+    }
+    let mut suffix = 2usize;
+    while candidate.exists() || !reserved.insert(candidate.clone()) {
+        candidate = requested.with_file_name(format!("{stem}-{id}-{suffix}"));
+        if let Some(extension) = requested.extension() {
+            candidate.set_extension(extension);
+        }
+        suffix += 1;
+    }
+    candidate
+}
+
+fn copy_file_exclusive(source: &Path, destination: &Path) -> Result<()> {
+    let mut input =
+        std::fs::File::open(source).with_context(|| format!("opening {}", source.display()))?;
+    let mut output = std::fs::OpenOptions::new()
+        .write(true)
+        .create_new(true)
+        .open(destination)
+        .with_context(|| format!("creating {}", destination.display()))?;
+    let result = std::io::copy(&mut input, &mut output)
+        .with_context(|| format!("copying {}", source.display()))
+        .and_then(|_| {
+            output
+                .sync_all()
+                .with_context(|| format!("syncing {}", destination.display()))
+        });
+    if let Err(error) = result {
+        drop(output);
+        let _ = std::fs::remove_file(destination);
+        return Err(error);
+    }
+    Ok(())
+}
+
+fn remove_empty_directories(root: &Path) {
+    let Ok(entries) = std::fs::read_dir(root) else {
+        return;
+    };
+    for entry in entries.flatten() {
+        let path = entry.path();
+        if path.is_dir() {
+            remove_empty_directories(&path);
+        }
+    }
+    let _ = std::fs::remove_dir(root);
+}
+
 fn cleanup_empty_releases(tx: &rusqlite::Transaction) -> rusqlite::Result<()> {
     tx.execute(
         "DELETE FROM releases WHERE id NOT IN (SELECT release_id FROM tracks)",
@@ -2779,6 +3426,32 @@ fn now_ms_i64() -> i64 {
         .unwrap_or(0)
 }
 
+fn embedding_to_bytes(vector: &[f32]) -> Vec<u8> {
+    let mut bytes = Vec::with_capacity(std::mem::size_of_val(vector));
+    for value in vector {
+        bytes.extend_from_slice(&value.to_le_bytes());
+    }
+    bytes
+}
+
+fn embedding_from_bytes(dimensions: i64, bytes: &[u8]) -> Result<Vec<f32>> {
+    anyhow::ensure!(dimensions > 0, "stored embedding has invalid dimensions");
+    let dimensions = dimensions as usize;
+    anyhow::ensure!(
+        bytes.len() == dimensions * std::mem::size_of::<f32>(),
+        "stored embedding byte length does not match its dimensions"
+    );
+    let vector: Vec<f32> = bytes
+        .chunks_exact(4)
+        .map(|chunk| f32::from_le_bytes([chunk[0], chunk[1], chunk[2], chunk[3]]))
+        .collect();
+    anyhow::ensure!(
+        vector.iter().all(|value| value.is_finite()),
+        "stored embedding contains a non-finite value"
+    );
+    Ok(vector)
+}
+
 fn remote_artist_id(artist_key: &str) -> i64 {
     let hash = blake3::hash(artist_key.as_bytes());
     let mut bytes = [0u8; 8];
@@ -2834,6 +3507,16 @@ fn ensure_schema_migrations(conn: &Connection) -> Result<()> {
             [],
         )?;
     }
+    let embedding_columns = table_columns(conn, "track_embeddings")?;
+    if !embedding_columns
+        .iter()
+        .any(|column| column == "routing_signature")
+    {
+        conn.execute(
+            "ALTER TABLE track_embeddings ADD COLUMN routing_signature BLOB",
+            [],
+        )?;
+    }
     let mut rows = conn.prepare("SELECT id, title FROM playlists WHERE sync_id IS NULL")?;
     let missing = rows
         .query_map([], |row| {

src/library/tests.rs

@@ -60,6 +60,138 @@ fn artist_filters(hide_featured_only: bool) -> crate::config::settings::LibraryF
     }
 }
 
+fn unique_test_dir(label: &str) -> std::path::PathBuf {
+    let unique = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap()
+        .as_nanos();
+    std::env::temp_dir().join(format!("furumi-{label}-{}-{unique}", std::process::id()))
+}
+
+#[test]
+fn managed_music_relocation_builds_artist_release_tree_and_updates_paths() {
+    let root = unique_test_dir("music-relocation");
+    let old = root.join("old");
+    let new = root.join("new");
+    let covers = root.join("covers");
+    std::fs::create_dir_all(&old).unwrap();
+    std::fs::create_dir_all(&covers).unwrap();
+    let audio = old.join("legacy.flac");
+    let cover = covers.join("release.jpg");
+    let artist_image = covers.join("artist.png");
+    std::fs::write(&audio, b"audio").unwrap();
+    std::fs::write(&cover, b"cover").unwrap();
+    std::fs::write(&artist_image, b"artist").unwrap();
+
+    let conn = Connection::open_in_memory().unwrap();
+    conn.pragma_update(None, "foreign_keys", "ON").unwrap();
+    register_norm_function(&conn).unwrap();
+    conn.execute_batch(SCHEMA).unwrap();
+    let library = Library {
+        conn: Mutex::new(conn),
+        db_path: root.join("library.db"),
+        covers_dir: covers,
+    };
+    let track_id = import::upsert_track(
+        &library,
+        &import::TrackImport {
+            file_path: audio.to_string_lossy().into_owned(),
+            title: "Song".into(),
+            artists: vec!["Artist".into()],
+            featured_artists: vec![],
+            album_artists: vec!["Artist".into()],
+            release_title: "Release".into(),
+            release_type: Some("album".into()),
+            year: Some(2026),
+            track_number: Some(1),
+            disc_number: Some(1),
+            duration_seconds: 1.0,
+            audio_format: Some("flac".into()),
+            audio_bitrate: None,
+            audio_sample_rate: None,
+            audio_bit_depth: None,
+            file_size_bytes: Some(5),
+            cover: None,
+        },
+    )
+    .unwrap()
+    .0;
+    let (release_id, artist_id): (i64, i64) = library
+        .lock()
+        .query_row(
+            "SELECT t.release_id, ta.artist_id
+             FROM tracks t JOIN track_artists ta ON ta.track_id = t.id
+             WHERE t.id = ?1 AND ta.role = 'main'",
+            [track_id],
+            |row| Ok((row.get(0)?, row.get(1)?)),
+        )
+        .unwrap();
+    library
+        .lock()
+        .execute(
+            "UPDATE releases SET cover_path = ?2 WHERE id = ?1",
+            params![release_id, cover.to_string_lossy()],
+        )
+        .unwrap();
+    library
+        .lock()
+        .execute(
+            "UPDATE artists SET image_path = ?2 WHERE id = ?1",
+            params![artist_id, artist_image.to_string_lossy()],
+        )
+        .unwrap();
+
+    let stats = library.relocate_managed_music(&old, &new).unwrap();
+    assert_eq!(stats.tracks, 1);
+    assert_eq!(stats.images, 2);
+    let track = library.tracks_by_ids(&[track_id]).unwrap().remove(0);
+    assert_eq!(
+        track.file_path,
+        new.join("Artist/Release/legacy.flac").to_string_lossy()
+    );
+    assert_eq!(
+        track.cover_path.as_deref(),
+        Some(
+            new.join("Artist/Release/cover.jpg")
+                .to_string_lossy()
+                .as_ref()
+        )
+    );
+    let image: String = library
+        .lock()
+        .query_row(
+            "SELECT image_path FROM artists WHERE id = ?1",
+            [artist_id],
+            |row| row.get(0),
+        )
+        .unwrap();
+    assert_eq!(image, new.join("Artist/artist.png").to_string_lossy());
+    assert!(!audio.exists());
+
+    std::fs::remove_dir_all(root).unwrap();
+}
+
+#[test]
+fn music_directory_validation_rejects_a_file_without_touching_it() {
+    let root = unique_test_dir("music-validation");
+    std::fs::create_dir_all(&root).unwrap();
+    let file = root.join("not-a-directory");
+    std::fs::write(&file, b"keep").unwrap();
+
+    assert!(Library::validate_music_directory(&file).is_err());
+    assert_eq!(std::fs::read(&file).unwrap(), b"keep");
+
+    std::fs::remove_dir_all(root).unwrap();
+}
+
+#[test]
+fn managed_music_names_are_portable_to_windows() {
+    assert_eq!(storage_name("Artist/Name", "fallback"), "Artist_Name");
+    assert_eq!(storage_name("CON", "fallback"), "_CON");
+    assert_eq!(storage_name("lpt9.live", "fallback"), "_lpt9.live");
+    assert_eq!(storage_name("...", "fallback"), "fallback");
+}
+
 #[test]
 fn local_stats_counts_library_rows_and_audio_bytes() {
     let lib = test_library();
@@ -554,3 +686,101 @@ fn listen_history_hides_unqualified_events_and_keeps_remote_metadata() {
     assert!(lib.apply_listen_event(&event, "remote-device").unwrap());
     assert!(lib.listen_history(20).unwrap().is_empty());
 }
+
+#[test]
+fn similarity_embeddings_round_trip_and_keep_profiles_separate() {
+    let lib = test_library();
+    let track_id = add_track(&lib, "Song", "Artist", "Album");
+    for profile in ["profile-a", "profile-b"] {
+        lib.ensure_similarity_profile(profile, "model", "1", "sha", "prep", 3)
+            .unwrap();
+    }
+    let track = lib
+        .pending_similarity_tracks("profile-a")
+        .unwrap()
+        .into_iter()
+        .find(|track| track.id == track_id)
+        .unwrap();
+    let first = [0.26726124, 0.5345225, 0.8017837];
+    let second = [0.8017837, 0.5345225, 0.26726124];
+    lib.store_similarity_embedding(&track, "profile-a", &first)
+        .unwrap();
+    lib.store_similarity_embedding(&track, "profile-b", &second)
+        .unwrap();
+
+    assert_eq!(
+        lib.similarity_embedding(track_id, "profile-a").unwrap(),
+        Some(first.to_vec())
+    );
+    assert_eq!(
+        lib.similarity_embedding(track_id, "profile-b").unwrap(),
+        Some(second.to_vec())
+    );
+    let stats = lib.similarity_storage_stats("profile-a").unwrap();
+    assert_eq!(stats.total_tracks, 1);
+    assert_eq!(stats.embedded_tracks, 1);
+    assert_eq!(stats.stored_vectors, 2);
+    assert_eq!(stats.stored_bytes, 24);
+    lib.lock()
+        .execute(
+            "UPDATE track_embeddings SET routing_signature = NULL WHERE profile_id = 'profile-a'",
+            [],
+        )
+        .unwrap();
+    assert_eq!(
+        lib.similarity_routing_signatures("profile-a")
+            .unwrap()
+            .len(),
+        1
+    );
+    let stored_signature_bytes: i64 = lib
+        .lock()
+        .query_row(
+            "SELECT length(routing_signature) FROM track_embeddings WHERE profile_id = 'profile-a'",
+            [],
+            |row| row.get(0),
+        )
+        .unwrap();
+    assert_eq!(stored_signature_bytes, 32);
+}
+
+#[test]
+fn changed_content_id_invalidates_only_the_stale_embedding() {
+    let lib = test_library();
+    let track_id = add_track(&lib, "Song", "Artist", "Album");
+    lib.ensure_similarity_profile("profile", "model", "1", "sha", "prep", 2)
+        .unwrap();
+    let track = lib.pending_similarity_tracks("profile").unwrap().remove(0);
+    lib.store_similarity_embedding(&track, "profile", &[0.6, 0.8])
+        .unwrap();
+    lib.lock()
+        .execute(
+            "UPDATE tracks SET content_id = ?2 WHERE id = ?1",
+            params![track_id, format!("b3:{}", "f".repeat(64))],
+        )
+        .unwrap();
+
+    assert_eq!(lib.pending_similarity_tracks("profile").unwrap().len(), 1);
+    assert_eq!(lib.similarity_embedding(track_id, "profile").unwrap(), None);
+    assert!(lib.load_similarity_index("profile").unwrap().is_empty());
+}
+
+#[test]
+fn clearing_embeddings_preserves_the_library() {
+    let lib = test_library();
+    let track_id = add_track(&lib, "Song", "Artist", "Album");
+    lib.ensure_similarity_profile("profile", "model", "1", "sha", "prep", 2)
+        .unwrap();
+    let track = lib.pending_similarity_tracks("profile").unwrap().remove(0);
+    lib.store_similarity_embedding(&track, "profile", &[0.6, 0.8])
+        .unwrap();
+
+    lib.clear_similarity_embeddings().unwrap();
+
+    assert_eq!(lib.tracks_by_ids(&[track_id]).unwrap().len(), 1);
+    assert!(
+        lib.similarity_embedding(track_id, "profile")
+            .unwrap()
+            .is_none()
+    );
+}

src/main.rs

@@ -8,6 +8,7 @@ mod library;
 mod media;
 mod player;
 mod share;
+mod similarity;
 mod status;
 mod streaming;
 mod ui;

src/media.rs

@@ -99,9 +99,10 @@ fn create_controls() -> Option<MediaControls> {
     #[cfg(not(target_os = "windows"))]
     let hwnd = None;
 
+    let dbus_name = platform_dbus_name();
     let config = PlatformConfig {
         display_name: "Furumi",
-        dbus_name: "cy.hexor.furumi",
+        dbus_name: &dbus_name,
         hwnd,
     };
     match MediaControls::new(config) {
@@ -113,6 +114,41 @@ fn create_controls() -> Option<MediaControls> {
     }
 }
 
+/// MPRIS well-known names must be unique on the session bus. Developers often
+/// run a checkout next to an installed Furumi, and souvlaki 0.8.3 reports a
+/// duplicate name by panicking in its private service thread. Ratatui's global
+/// panic hook then restores the terminal even though the app thread is still
+/// alive, leaving a frozen UI in canonical/echo mode.
+///
+/// Give every Unix MPRIS instance its own valid bus-name component. Other
+/// backends ignore `dbus_name`, so retain the stable application identifier
+/// there.
+fn platform_dbus_name() -> String {
+    #[cfg(all(
+        unix,
+        not(any(target_os = "macos", target_os = "ios", target_os = "android"))
+    ))]
+    {
+        mpris_dbus_name(std::process::id())
+    }
+
+    #[cfg(not(all(
+        unix,
+        not(any(target_os = "macos", target_os = "ios", target_os = "android"))
+    )))]
+    {
+        "cy.hexor.furumi".to_string()
+    }
+}
+
+#[cfg(all(
+    unix,
+    not(any(target_os = "macos", target_os = "ios", target_os = "android"))
+))]
+fn mpris_dbus_name(process_id: u32) -> String {
+    format!("cy.hexor.furumi.instance{process_id}")
+}
+
 /// An invisible top-level window owning the SMTC session. Created on the
 /// main thread, which also pumps its messages in `pump_platform_events`.
 #[cfg(target_os = "windows")]
@@ -217,3 +253,18 @@ fn pump_platform_events() {
 
 #[cfg(not(any(target_os = "macos", target_os = "windows")))]
 fn pump_platform_events() {}
+
+#[cfg(test)]
+mod tests {
+    #[cfg(all(
+        unix,
+        not(any(target_os = "macos", target_os = "ios", target_os = "android"))
+    ))]
+    #[test]
+    fn mpris_names_are_distinct_between_processes() {
+        let first = super::mpris_dbus_name(41);
+        let second = super::mpris_dbus_name(42);
+        assert_eq!(first, "cy.hexor.furumi.instance41");
+        assert_ne!(first, second);
+    }
+}

src/ui/federation.rs

@@ -7,7 +7,7 @@ use ratatui::text::{Line, Span};
 use ratatui::widgets::{Block, Paragraph};
 
 use super::theme;
-use crate::app::state::{AppState, DevicePresenceSection, FedRow, settings_rows};
+use crate::app::state::{AppState, DevicePresenceSection, FedRow, SimilarityRow, settings_rows};
 
 pub fn draw(frame: &mut Frame, area: Rect, state: &AppState) {
     let block = Block::bordered()
@@ -28,12 +28,12 @@ pub fn draw(frame: &mut Frame, area: Rect, state: &AppState) {
         .areas(inner);
 
         draw_settings_rows(frame, rows_area, state);
-        draw_status(frame, status_area, state);
+        draw_status_column(frame, status_area, state);
         return;
     }
 
     let rows_height =
-        (settings_rows(state).len() + 6 + device_presence_sections(state).len()) as u16;
+        (settings_rows(state).len() + 10 + device_presence_sections(state).len()) as u16;
     let [rows_area, _, status_area] = Layout::vertical([
         Constraint::Length(rows_height.min(inner.height)),
         Constraint::Length(1),
@@ -42,7 +42,7 @@ pub fn draw(frame: &mut Frame, area: Rect, state: &AppState) {
     .areas(inner);
 
     draw_settings_rows(frame, rows_area, state);
-    draw_status(frame, status_area, state);
+    draw_status_column(frame, status_area, state);
 }
 
 fn device_presence_sections(state: &AppState) -> Vec<DevicePresenceSection> {
@@ -69,6 +69,66 @@ fn draw_settings_rows(frame: &mut Frame, area: Rect, state: &AppState) {
     let mut y = area.y;
     let mut cursor = 0usize;
 
+    draw_section(frame, area, state, &mut y, "Library");
+    draw_row(
+        frame,
+        area,
+        state,
+        &mut y,
+        cursor,
+        state.settings_cursor,
+        "Music save directory",
+        if state.music_dir_changing {
+            format!("{} checking/changing…", state.spinner())
+        } else {
+            state.music_dir.to_string_lossy().into_owned()
+        },
+    );
+    cursor += 1;
+
+    y = y.saturating_add(1);
+
+    draw_section(frame, area, state, &mut y, "Similarity Search");
+    let similarity = &state.similarity.settings;
+    for row in SimilarityRow::ALL {
+        let (label, value) = match row {
+            SimilarityRow::Toggle => ("Similarity search", on_off(similarity.enabled).to_string()),
+            SimilarityRow::Model => (
+                "Embedding model",
+                crate::similarity::model_by_id(&similarity.model)
+                    .map(|model| format!("{} · {}", model.id, model.license))
+                    .unwrap_or_else(|| similarity.model.clone()),
+            ),
+            SimilarityRow::Profile => (
+                "Preprocessing profile",
+                format!("{} (enter for details)", similarity.profile),
+            ),
+            SimilarityRow::MinimumScore => (
+                "Minimum similarity",
+                format!("{:.2}", similarity.minimum_score),
+            ),
+            SimilarityRow::MaxTracksPerArtist => (
+                "Tracks per artist",
+                similarity.max_tracks_per_artist.to_string(),
+            ),
+            SimilarityRow::Workers => ("Background workers", similarity.workers.to_string()),
+            SimilarityRow::Clear => ("Clear all stored embeddings", "↵".to_string()),
+        };
+        draw_row(
+            frame,
+            area,
+            state,
+            &mut y,
+            cursor,
+            state.settings_cursor,
+            label,
+            value,
+        );
+        cursor += 1;
+    }
+
+    y = y.saturating_add(1);
+
     draw_section(frame, area, state, &mut y, "Federation");
     for row in FedRow::ALL {
         let (label, value) = match row {
@@ -347,6 +407,8 @@ fn protocol_label(id: &str) -> &str {
         "music_dht" => "Music DHT",
         "catalog" => "Catalog",
         "audio" => "Audio transfer",
+        "similarity" => "Similarity search",
+        "similarity_dht" => "Similarity DHT",
         "device_sync" => "Device sync",
         "jam" => "Jam",
         other => other,
@@ -486,6 +548,61 @@ fn short_id(id: &str) -> String {
     id.chars().take(12).collect::<String>() + "…"
 }
 
+fn draw_status_column(frame: &mut Frame, area: Rect, state: &AppState) {
+    draw_status(frame, area, state);
+}
+
+fn draw_similarity_status(frame: &mut Frame, area: Rect, state: &AppState) {
+    draw_summary_card(
+        frame,
+        area,
+        state,
+        " Similarity Processing ",
+        similarity_summary_lines(state),
+    );
+}
+
+fn similarity_summary_lines(state: &AppState) -> Vec<Line<'static>> {
+    let status = &state.similarity.status;
+    let progress = if status.total_tracks == 0 {
+        "0 / 0".to_string()
+    } else {
+        format!("{} / {}", status.completed_tracks, status.total_tracks)
+    };
+    let active = status
+        .active_profile
+        .as_deref()
+        .map(short_id)
+        .unwrap_or_else(|| "not ready".to_string());
+    let target = status
+        .target_profile
+        .as_deref()
+        .map(short_id)
+        .unwrap_or_else(|| "—".to_string());
+    vec![
+        summary_line("State", status.phase.label().to_string()),
+        summary_line("Progress", progress),
+        summary_line("Active", active),
+        summary_line("Processing", target),
+        summary_line(
+            "Stored",
+            format!(
+                "{} vectors / {}",
+                status.stored_vectors,
+                short_bytes_label(status.stored_bytes)
+            ),
+        ),
+        summary_line(
+            "Current",
+            status
+                .current_track
+                .clone()
+                .or_else(|| status.last_error.clone())
+                .unwrap_or_else(|| format!("{} errors", status.failed_tracks)),
+        ),
+    ]
+}
+
 fn draw_status(frame: &mut Frame, area: Rect, state: &AppState) {
     if area.width == 0 || area.height == 0 {
         return;
@@ -500,69 +617,81 @@ fn draw_status(frame: &mut Frame, area: Rect, state: &AppState) {
         return;
     }
 
-    if area.width >= 60 && area.height >= 20 {
-        let protocols_height =
-            protocol_card_height(state, area.width.saturating_sub(2), area.height);
-        let [top_area, _, bottom_area, _, protocols_area, _] = Layout::vertical([
-            Constraint::Length(7),
-            Constraint::Length(1),
-            Constraint::Length(7),
-            Constraint::Length(1),
-            Constraint::Length(protocols_height),
-            Constraint::Min(0),
-        ])
-        .areas(area);
-        let [status_area, _, local_area] = Layout::horizontal([
-            Constraint::Percentage(50),
-            Constraint::Length(1),
-            Constraint::Percentage(50),
-        ])
-        .areas(top_area);
-        let [transport_area, _, devices_area] = Layout::horizontal([
-            Constraint::Percentage(50),
-            Constraint::Length(1),
-            Constraint::Percentage(50),
-        ])
-        .areas(bottom_area);
-        draw_summary_card(
-            frame,
-            status_area,
-            state,
-            " Status ",
-            node_summary_lines(state),
-        );
-        draw_summary_card(
-            frame,
-            local_area,
-            state,
-            " Local Data ",
-            local_data_summary_lines(state),
-        );
-        draw_summary_card(
-            frame,
-            transport_area,
-            state,
-            " Iroh Transport ",
-            transport_summary_lines(state),
-        );
-        draw_summary_card(
-            frame,
-            devices_area,
-            state,
-            " Connected Devices ",
-            device_summary_lines(state),
-        );
-        draw_summary_card(
-            frame,
-            protocols_area,
-            state,
-            " Protocol Versions ",
-            protocol_summary_lines(state, protocols_area.width.saturating_sub(2)),
-        );
-        return;
+    if area.width >= 60 {
+        let paired_width = area.width.saturating_sub(1) / 2;
+        let paired_height =
+            protocol_card_height(state, paired_width.saturating_sub(2), area.height).max(8);
+        if area.height >= 16 + paired_height {
+            let [top_area, _, middle_area, _, paired_area, _] = Layout::vertical([
+                Constraint::Length(7),
+                Constraint::Length(1),
+                Constraint::Length(7),
+                Constraint::Length(1),
+                Constraint::Length(paired_height),
+                Constraint::Min(0),
+            ])
+            .areas(area);
+            let [status_area, _, local_area] = Layout::horizontal([
+                Constraint::Percentage(50),
+                Constraint::Length(1),
+                Constraint::Percentage(50),
+            ])
+            .areas(top_area);
+            let [transport_area, _, devices_area] = Layout::horizontal([
+                Constraint::Percentage(50),
+                Constraint::Length(1),
+                Constraint::Percentage(50),
+            ])
+            .areas(middle_area);
+            let [similarity_area, _, protocols_area] = Layout::horizontal([
+                Constraint::Percentage(50),
+                Constraint::Length(1),
+                Constraint::Percentage(50),
+            ])
+            .areas(paired_area);
+            draw_summary_card(
+                frame,
+                status_area,
+                state,
+                " Status ",
+                node_summary_lines(state),
+            );
+            draw_summary_card(
+                frame,
+                local_area,
+                state,
+                " Local Data ",
+                local_data_summary_lines(state),
+            );
+            draw_summary_card(
+                frame,
+                transport_area,
+                state,
+                " Iroh Transport ",
+                transport_summary_lines(state),
+            );
+            draw_summary_card(
+                frame,
+                devices_area,
+                state,
+                " Connected Devices ",
+                device_summary_lines(state),
+            );
+            draw_similarity_status(frame, similarity_area, state);
+            draw_summary_card(
+                frame,
+                protocols_area,
+                state,
+                " Protocol Versions ",
+                protocol_summary_lines(state, protocols_area.width.saturating_sub(2)),
+            );
+            return;
+        }
     }
 
-    if area.height < 39 {
+    let protocols_height = protocol_card_height(state, area.width.saturating_sub(2), area.height);
+    let required_vertical_height = 41u16.saturating_add(protocols_height);
+    if area.height < required_vertical_height {
         frame.render_widget(
             Paragraph::new(compact_status_lines(state))
                 .wrap(ratatui::widgets::Wrap { trim: false }),
@@ -580,6 +709,8 @@ fn draw_status(frame: &mut Frame, area: Rect, state: &AppState) {
         _,
         local_area,
         _,
+        similarity_area,
+        _,
         protocols_area,
         _,
     ] = Layout::vertical([
@@ -591,11 +722,9 @@ fn draw_status(frame: &mut Frame, area: Rect, state: &AppState) {
         Constraint::Length(1),
         Constraint::Length(7),
         Constraint::Length(1),
-        Constraint::Length(protocol_card_height(
-            state,
-            area.width.saturating_sub(2),
-            area.height,
-        )),
+        Constraint::Length(8),
+        Constraint::Length(1),
+        Constraint::Length(protocols_height),
         Constraint::Min(0),
     ])
     .areas(area);
@@ -628,6 +757,7 @@ fn draw_status(frame: &mut Frame, area: Rect, state: &AppState) {
         " Local Data ",
         local_data_summary_lines(state),
     );
+    draw_similarity_status(frame, similarity_area, state);
     draw_summary_card(
         frame,
         protocols_area,
@@ -651,6 +781,12 @@ fn compact_status_lines(state: &AppState) -> Vec<Line<'static>> {
     lines.push(Line::styled("Connected Devices", theme::header_for(state)));
     lines.extend(device_summary_lines(state).into_iter().take(2));
     lines.push(Line::default());
+    lines.push(Line::styled(
+        "Similarity Processing",
+        theme::header_for(state),
+    ));
+    lines.extend(similarity_summary_lines(state).into_iter().take(3));
+    lines.push(Line::default());
     lines.push(Line::styled("Protocol Versions", theme::header_for(state)));
     lines.extend(protocol_summary_lines(state, 0).into_iter().take(3));
     lines

src/ui/global.rs

@@ -890,11 +890,19 @@ fn draw_release(frame: &mut Frame, area: Rect, state: &AppState, id: i64, cursor
 
 fn draw_search(frame: &mut Frame, area: Rect, state: &AppState, cursor: usize) {
     let search = &state.search;
-    let mut title = format!(" Search: {} ", search.query);
+    let prefix = if search.similarity_source.is_some() {
+        "Search similar to"
+    } else {
+        "Search"
+    };
+    let mut title = format!(" {prefix}: {} ", search.query);
     if search.loading {
         title.push_str("· searching… ");
     }
     let inner = bordered(frame, area, state, title);
+    if search.similarity_source.is_some() {
+        return draw_similarity_search(frame, inner, state, cursor);
+    }
 
     let empty_results = SearchResults::default();
     let results = match &search.results {
@@ -1097,6 +1105,156 @@ fn draw_search(frame: &mut Frame, area: Rect, state: &AppState, cursor: usize) {
     }
 }
 
+fn draw_similarity_search(frame: &mut Frame, area: Rect, state: &AppState, cursor: usize) {
+    let search = &state.search;
+    let status = if search.fed_loading {
+        super::loading_line(state, "searching federation…")
+    } else if let Some(stats) = &search.similarity_stats {
+        let elapsed = if stats.elapsed_ms < 1_000 {
+            format!("{} ms", stats.elapsed_ms)
+        } else {
+            format!("{:.2} s", stats.elapsed_ms as f64 / 1_000.0)
+        };
+        Line::from(vec![
+            Span::styled("Federation · ", theme::accent_for(state)),
+            Span::styled(
+                format!(
+                    "{} tracks · {} artists · {} peers queried · {elapsed}",
+                    stats.tracks, stats.artists, stats.peers_queried
+                ),
+                theme::dim(),
+            ),
+        ])
+    } else if search.similarity_error.is_some() {
+        Line::styled(
+            "Federation search failed · showing local results",
+            error_style(),
+        )
+    } else if search.loading {
+        super::loading_line(state, "preparing local similarity search…")
+    } else {
+        Line::styled("Federation disabled · showing local results", theme::dim())
+    };
+    let [status_area, content] =
+        Layout::vertical([Constraint::Length(1), Constraint::Min(0)]).areas(area);
+    frame.render_widget(Paragraph::new(status), status_area);
+
+    let mut rows: Vec<(Line, Option<String>, Option<usize>)> = Vec::new();
+    rows.push((Line::styled("Tracks", theme::header_for(state)), None, None));
+    if let Some(track) = &search.similarity_source_track {
+        let heart = if state.track_liked(track) {
+            Span::styled("♥ ", theme::accent_for(state))
+        } else {
+            Span::raw("  ")
+        };
+        rows.push((
+            Line::from(vec![
+                heart,
+                Span::raw(track.title.clone()),
+                Span::styled(
+                    format!("  {} · {}", track.artist_line(), track.release_title),
+                    theme::dim(),
+                ),
+            ]),
+            Some(super::track_meta_suffix(track, true)),
+            Some(0),
+        ));
+    }
+    for (offset, hit) in search.similarity_tracks.iter().enumerate() {
+        let index = offset + 1;
+        match hit {
+            crate::app::state::SimilaritySearchHit::Local { track, .. } => {
+                let heart = if state.track_liked(track) {
+                    Span::styled("♥ ", theme::accent_for(state))
+                } else {
+                    Span::raw("  ")
+                };
+                rows.push((
+                    Line::from(vec![
+                        heart,
+                        Span::raw(track.title.clone()),
+                        Span::styled(
+                            format!("  {} · {}", track.artist_line(), track.release_title),
+                            theme::dim(),
+                        ),
+                    ]),
+                    Some(super::track_meta_suffix(track, true)),
+                    Some(index),
+                ));
+            }
+            crate::app::state::SimilaritySearchHit::Federated { track, .. } => {
+                let heart = if state.fed_track_liked(track) {
+                    Span::styled("♥ ", theme::accent_for(state))
+                } else {
+                    Span::raw("  ")
+                };
+                let origin = if track.own {
+                    "your library".to_string()
+                } else {
+                    format!("peer {}…", track.owner_short())
+                };
+                let mut meta = track.duration_label();
+                if let Some(year) = track.year {
+                    if !meta.is_empty() {
+                        meta.push_str(" · ");
+                    }
+                    meta.push_str(&year.to_string());
+                }
+                rows.push((
+                    Line::from(vec![
+                        heart,
+                        fed_track_availability_prefix(state, track),
+                        Span::raw(track.title.clone()),
+                        Span::styled(
+                            format!("  {} · {origin}", track.artist_line()),
+                            theme::dim(),
+                        ),
+                    ]),
+                    Some(meta),
+                    Some(index),
+                ));
+            }
+        }
+    }
+
+    let scope = crate::app::state::TrackSelectionScope::SimilaritySearch;
+    let mut selected = std::collections::HashSet::new();
+    if state.track_selection.is_active_for(&scope)
+        && let Some(indices) = state
+            .track_selection
+            .indices(&scope, search.similarity_len())
+    {
+        selected.extend(indices);
+    }
+    let cursor_row = rows
+        .iter()
+        .position(|(_, _, row_cursor)| *row_cursor == Some(cursor))
+        .unwrap_or(0);
+    let visible = usize::from(content.height.max(1));
+    let first = cursor_row
+        .saturating_sub(visible / 2)
+        .min(rows.len().saturating_sub(visible));
+    for (offset, (line, right, row_cursor)) in
+        rows.into_iter().enumerate().skip(first).take(visible)
+    {
+        let rect = Rect {
+            x: content.x,
+            y: content.y + (offset - first) as u16,
+            width: content.width,
+            height: 1,
+        };
+        if let Some(row_index) = row_cursor
+            && selected.contains(&row_index)
+            && row_index != cursor
+        {
+            frame
+                .buffer_mut()
+                .set_style(rect, theme::selection_for(state));
+        }
+        draw_row(frame, rect, state, line, right, row_cursor == Some(cursor));
+    }
+}
+
 // ---------------------------------------------------------------------------
 // Federated artist card (assembled from peer catalogs)
 // ---------------------------------------------------------------------------

src/ui/mod.rs

@@ -258,7 +258,7 @@ fn draw_queue(frame: &mut Frame, area: Rect, state: &AppState) {
     let player = &state.player;
     let block = Block::bordered()
         .title(format!(
-            " Queue — {} tracks · Mode: {} · enter: play · d: remove · shift-v: select · :clear ",
+            " Queue — {} tracks · Mode: {} · enter: play · alt-j/k: move · d: remove · shift-v: select · :clear ",
             player.queue.len(),
             state.global.filters.source_mode.label()
         ))

src/ui/popup.rs

@@ -25,6 +25,10 @@ pub fn draw(frame: &mut Frame, state: &AppState) {
             ..
         }) => draw_edit(frame, state, title, fields, *focus, error.as_deref()),
         Some(Popup::ConfirmDelete { label, .. }) => draw_confirm_delete(frame, state, label),
+        Some(Popup::SimilarityPrivacyConsent { .. }) => {
+            draw_similarity_privacy_consent(frame, state)
+        }
+        Some(Popup::ConfirmClearEmbeddings) => draw_confirm_clear_embeddings(frame, state),
         Some(Popup::LibraryFilters { cursor }) => draw_library_filters(frame, state, *cursor),
         Some(Popup::TrackInfo {
             tracks,
@@ -42,8 +46,15 @@ pub fn draw(frame: &mut Frame, state: &AppState) {
             draw_fed_input(frame, state, field.title(), field.help(), input)
         }
         Some(Popup::FedText { title, text }) => draw_fed_text(frame, state, title, text),
-        Some(Popup::FedCopyText { title, text, help }) => {
-            draw_fed_copy_text(frame, state, title, text, help)
+        Some(Popup::FedCopyText {
+            title,
+            text,
+            help,
+            cursor,
+        }) => draw_fed_copy_text(frame, state, title, text, help, *cursor),
+        Some(Popup::PlainText { .. }) => {}
+        Some(Popup::ConfirmMusicDirectory { path }) => {
+            draw_music_directory_confirmation(frame, state, path)
         }
         Some(Popup::FederationStatusDetails {
             focus,
@@ -93,6 +104,79 @@ pub fn draw(frame: &mut Frame, state: &AppState) {
     }
 }
 
+fn draw_similarity_privacy_consent(frame: &mut Frame, state: &AppState) {
+    let area = centered(frame.area(), 78, 11);
+    let block = Block::bordered()
+        .title(" Similarity search and federation ")
+        .title_style(theme::header_for(state))
+        .border_style(theme::strong_border_for(state));
+    let inner = block.inner(area);
+    frame.render_widget(Clear, area);
+    frame.render_widget(block, area);
+    frame.render_widget(
+        Paragraph::new(vec![
+            Line::raw("To find similar music on other peers, Furumi sends them an"),
+            Line::raw("anonymous numeric embedding of the selected track."),
+            Line::raw(""),
+            Line::raw("It contains no account identity, but a peer may technically"),
+            Line::raw("infer what kind of music you are searching from it."),
+            Line::raw(""),
+            Line::styled("enter/y: agree and enable · n/esc: cancel", theme::dim()),
+        ])
+        .wrap(Wrap { trim: true }),
+        inner,
+    );
+}
+
+fn draw_confirm_clear_embeddings(frame: &mut Frame, state: &AppState) {
+    let area = centered(frame.area(), 70, 8);
+    let block = Block::bordered()
+        .title(" Clear embeddings? ")
+        .title_style(theme::header_for(state))
+        .border_style(theme::strong_border_for(state));
+    let inner = block.inner(area);
+    frame.render_widget(Clear, area);
+    frame.render_widget(block, area);
+    frame.render_widget(
+        Paragraph::new(vec![
+            Line::raw("All model/profile embeddings will be removed from SQLite."),
+            Line::raw("Audio and library metadata stay untouched."),
+            Line::raw("If enabled, processing starts again automatically."),
+            Line::raw(""),
+            Line::styled("enter/y: clear · n/esc: cancel", theme::dim()),
+        ]),
+        inner,
+    );
+}
+
+fn draw_music_directory_confirmation(frame: &mut Frame, state: &AppState, path: &std::path::Path) {
+    let area = centered(frame.area(), 76, 9);
+    let block = Block::bordered()
+        .title(" Move existing music? ")
+        .title_style(theme::header_for(state))
+        .border_style(theme::strong_border_for(state));
+    let inner = block.inner(area);
+    frame.render_widget(Clear, area);
+    frame.render_widget(block, area);
+    frame.render_widget(
+        Paragraph::new(vec![
+            Line::raw("The destination is writable:"),
+            Line::styled(
+                path.to_string_lossy().into_owned(),
+                theme::accent_for(state),
+            ),
+            Line::raw(""),
+            Line::raw("Move music and artwork previously saved by Furumi there?"),
+            Line::styled(
+                "enter/y move · n keep existing files where they are · esc cancel",
+                theme::dim(),
+            ),
+        ])
+        .wrap(Wrap { trim: false }),
+        inner,
+    );
+}
+
 fn draw_listen_history(frame: &mut Frame, state: &AppState, cursor: usize) {
     let area = centered(
         frame.area(),
@@ -838,11 +922,19 @@ fn draw_fed_input(
     );
 }
 
-/// Read-only wrapped text (this peer's federation ticket).
+/// Read-only wrapped text.
 fn draw_fed_text(frame: &mut Frame, state: &AppState, title: &str, text: &str) {
     let width = frame.area().width.saturating_sub(8).clamp(24, 90);
     let text_width = usize::from(width.saturating_sub(2));
-    let lines_needed = (text.chars().count() / text_width.max(1) + 3) as u16;
+    let lines_needed = text
+        .lines()
+        .map(|line| {
+            UnicodeWidthStr::width(line)
+                .max(1)
+                .div_ceil(text_width.max(1))
+        })
+        .sum::<usize>()
+        .saturating_add(2) as u16;
     let area = centered(
         frame.area(),
         width,
@@ -862,7 +954,14 @@ fn draw_fed_text(frame: &mut Frame, state: &AppState, title: &str, text: &str) {
 }
 
 /// Wrapped text with an explicit copy-and-close action.
-fn draw_fed_copy_text(frame: &mut Frame, state: &AppState, title: &str, text: &str, help: &str) {
+fn draw_fed_copy_text(
+    frame: &mut Frame,
+    state: &AppState,
+    title: &str,
+    text: &str,
+    help: &str,
+    cursor: usize,
+) {
     let width = frame.area().width.saturating_sub(8).clamp(36, 96);
     let text_width = usize::from(width.saturating_sub(2));
     let text_lines = (text.chars().count() / text_width.max(1) + 1) as u16;
@@ -894,17 +993,28 @@ fn draw_fed_copy_text(frame: &mut Frame, state: &AppState, title: &str, text: &s
         Paragraph::new(text.to_string()).wrap(Wrap { trim: false }),
         body_area,
     );
+    let button = |label: &str, selected: bool| {
+        if selected {
+            Span::styled(format!(" {label} "), theme::tab_active_for(state))
+        } else {
+            Span::styled(format!(" {label} "), theme::dim())
+        }
+    };
     frame.render_widget(
-        Paragraph::new(Line::styled(
-            " Copy to clipboard and close ",
-            theme::tab_active_for(state),
-        ))
+        Paragraph::new(Line::from(vec![
+            button("Copy to clipboard", cursor == 0),
+            Span::raw("   "),
+            button("Show as plain terminal line", cursor == 1),
+        ]))
         .alignment(Alignment::Center),
         button_area,
     );
     frame.render_widget(
-        Paragraph::new(Line::styled("enter/c copy · esc close", theme::dim()))
-            .alignment(Alignment::Center),
+        Paragraph::new(Line::styled(
+            "left/right choose · enter apply · c copy · p plain line · esc close",
+            theme::dim(),
+        ))
+        .alignment(Alignment::Center),
         footer_area,
     );
 }
@@ -1228,12 +1338,22 @@ fn draw_track_info(
     );
 
     let can_share = crate::share::track_can_share(track);
-    let hint = if tracks.len() > 1 && can_share {
+    let can_similar =
+        state.similarity.settings.enabled && track.id >= 0 && !track.file_path.is_empty();
+    let hint = if tracks.len() > 1 && can_share && can_similar {
+        "j/k scroll · h/left previous · l/right next · a artist · s similar · c copy link · esc"
+    } else if tracks.len() > 1 && can_share {
         "j/k scroll · h/left previous · l/right next · a artist · c copy frid link · esc close"
+    } else if tracks.len() > 1 && can_similar {
+        "j/k scroll · h/left previous · l/right next · a artist · s similar · esc close"
     } else if tracks.len() > 1 {
         "j/k scroll · h/left previous · l/right next · a artist · esc close"
+    } else if can_share && can_similar {
+        "j/k scroll · a artist · s similar · c copy link · esc close"
     } else if can_share {
         "j/k scroll · a artist · c copy frid link · esc close"
+    } else if can_similar {
+        "j/k scroll · a artist · s similar · esc close"
     } else {
         "j/k scroll · a artist · esc close"
     };