Improved DHT publication. Adjust batching, added validation per key

.gitignore

@@ -2,3 +2,4 @@
 /nul
 /.claude
 /media
+/federation

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "furumusic"
-version = "0.6.0-fd"
+version = "0.7.0"
 edition = "2024"
 description = "Reusable web-app boilerplate: auth, OIDC/SSO, admin panel, user management, i18n, PostgreSQL"
 
@@ -16,6 +16,7 @@ reqwest = { version = "0.12", default-features = false, features = ["rustls-tls"
 tokio = { version = "1", features = ["sync", "fs", "io-util"] }
 tower = "0.5"
 base64 = "0.22"
+blake3 = "1"
 serde_json = "1"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
@@ -31,6 +32,7 @@ anyhow = "1.0"
 tokio-cron-scheduler = "0.15"
 croner = "3"
 async-trait = "0.1"
+postcard = { version = "1", features = ["alloc"] }
 uuid = "1"
 librqbit = { version = "8.1.1", features = ["disable-upload"] }
 # P2P federation: publishes the library into a shared DHT and serves audio /

federation/identity.key

@@ -1 +0,0 @@
-f48e5b2499a4ce1be021b2132401de29a1c23e84163d22e778874a8950757ff1

src/federation/mod.rs

@@ -13,20 +13,24 @@
 //! starts, stops or re-joins the node without a server restart.
 
 mod serve;
+mod storage;
 
+use std::collections::{HashMap, HashSet};
 use std::path::PathBuf;
 use std::sync::{Arc, OnceLock};
 use std::time::Duration;
 
 use anyhow::{Context, Result};
 use music_dht::{
-    ItemKind, ItemSpec, MusicDhtConfig, MusicDhtService, NetworkId, PeerTicket, RendezvousConfig,
+    ItemKind, ItemSpec, MusicDhtConfig, MusicDhtService, NetworkId, PeerTicket, PublishStats,
+    RendezvousConfig, SyncStats,
 };
 use serde_json::{Value, json};
 use sqlx::PgPool;
 use sqlx::Row as _;
 
 use crate::config::AppConfig;
+use storage::PostgresFederationStorage;
 
 pub use serve::{AUDIO_ALPN, CATALOG_ALPN};
 
@@ -39,10 +43,19 @@ struct Running {
     tasks: Vec<tokio::task::JoinHandle<()>>,
 }
 
+struct ContentHashJob {
+    media_file_id: i64,
+    sha256_hash: String,
+    file_path: String,
+}
+
 pub struct Federation {
-    /// Directory for the peer identity and DHT replica state.
+    /// Transport data directory; server-side DHT state and identity live in PostgreSQL.
     data_dir: PathBuf,
     database_url: std::sync::Mutex<String>,
+    storage_dir: std::sync::Mutex<String>,
+    content_cache: std::sync::Mutex<HashMap<i64, (String, String)>>,
+    content_pending: std::sync::Mutex<HashSet<i64>>,
     pool: tokio::sync::OnceCell<PgPool>,
     running: tokio::sync::Mutex<Option<Running>>,
     last_sync: std::sync::Mutex<Option<String>>,
@@ -66,6 +79,9 @@ pub fn handle() -> Arc<Federation> {
         Arc::new(Federation {
             data_dir: PathBuf::from(crate::media_paths::resolve_config_path("federation")),
             database_url: std::sync::Mutex::new(String::new()),
+            storage_dir: std::sync::Mutex::new(String::new()),
+            content_cache: std::sync::Mutex::new(Default::default()),
+            content_pending: std::sync::Mutex::new(Default::default()),
             pool: tokio::sync::OnceCell::new(),
             running: tokio::sync::Mutex::new(None),
             last_sync: std::sync::Mutex::new(None),
@@ -134,8 +150,7 @@ impl Federation {
                 }
                 "federation_network_id" => effective.federation_network_id = value,
                 "agent_storage_dir" => {
-                    effective.agent_storage_dir =
-                        crate::media_paths::resolve_config_path(&value);
+                    effective.agent_storage_dir = crate::media_paths::resolve_config_path(&value);
                 }
                 _ => {}
             }
@@ -147,6 +162,7 @@ impl Federation {
     /// node. Called at boot and every time the admin settings are saved.
     pub async fn apply(self: &Arc<Self>, config: &AppConfig) {
         *lock(&self.database_url) = config.database_url.clone();
+        *lock(&self.storage_dir) = config.agent_storage_dir.clone();
         let network = config.federation_network_id.trim().to_string();
         if config.federation_enabled && !network.is_empty() {
             if let Err(err) = self.start(network, config.agent_storage_dir.clone()).await {
@@ -170,6 +186,9 @@ impl Federation {
             stop_running(guard.take()).await;
         }
 
+        let dht_storage = Arc::new(PostgresFederationStorage::new(pool.clone()).await?);
+        let secret_key = dht_storage.load_or_create_secret_key().await?;
+
         let config = MusicDhtConfig::builder()
             .data_dir(&self.data_dir)
             .network_id(NetworkId::from_name(&network_name))
@@ -179,9 +198,10 @@ impl Federation {
             .stream_protocol(CATALOG_ALPN)
             .build()
             .map_err(|err| anyhow::anyhow!("invalid federation config: {err}"))?;
-        let (service, mut events) = MusicDhtService::start(config)
-            .await
-            .map_err(|err| anyhow::anyhow!("failed to start the DHT node: {err}"))?;
+        let (service, mut events) =
+            MusicDhtService::start_with_storage_and_secret_key(config, dht_storage, secret_key)
+                .await
+                .map_err(|err| anyhow::anyhow!("failed to start the DHT node: {err}"))?;
         let service = Arc::new(service);
         tracing::info!(
             endpoint_id = %service.endpoint_id(),
@@ -202,7 +222,7 @@ impl Federation {
             let mut interval = tokio::time::interval(SYNC_INTERVAL);
             loop {
                 interval.tick().await;
-                sync_self.sync_once(&sync_service).await;
+                let _ = sync_self.sync_once(&sync_service).await;
             }
         });
         // Serve audio and catalog requests from other peers.
@@ -254,54 +274,94 @@ impl Federation {
     async fn spawn_sync_soon(self: &Arc<Self>) {
         if let Ok(service) = self.service().await {
             let fed = Arc::clone(self);
-            tokio::spawn(async move { fed.sync_once(&service).await });
+            tokio::spawn(async move {
+                let _ = fed.sync_once(&service).await;
+            });
         }
     }
 
     pub async fn sync_now(self: &Arc<Self>) -> Result<()> {
         let service = self.service().await?;
-        self.sync_once(&service).await;
+        let sync_stats = self.sync_once(&service).await?;
+        let publish_stats = match service.republish().await {
+            Ok(stats) => stats,
+            Err(err) => {
+                tracing::warn!("federation republish failed: {err}");
+                self.set_error(Some(format!("republish failed: {err}")));
+                anyhow::bail!("republish failed: {err}");
+            }
+        };
+        self.record_publish_success(sync_stats, publish_stats);
         Ok(())
     }
 
-    async fn sync_once(&self, service: &MusicDhtService) {
+    async fn sync_once(self: &Arc<Self>, service: &MusicDhtService) -> Result<SyncStats> {
         let specs = match self.collect_specs().await {
             Ok(specs) => specs,
             Err(err) => {
                 tracing::warn!("federation sync: library read failed: {err:#}");
                 self.set_error(Some(format!("library read failed: {err}")));
-                return;
+                anyhow::bail!("library read failed: {err}");
             }
         };
         match service.sync_library(specs).await {
             Ok(stats) => {
-                *lock(&self.last_sync) = Some(format!(
-                    "{} (+{} ~{} −{}, unchanged {})",
-                    now_iso(),
-                    stats.added,
-                    stats.updated,
-                    stats.removed,
-                    stats.unchanged
-                ));
-                self.set_error(None);
+                self.record_sync_success(stats);
+                if stats.failed > 0 {
+                    self.set_error(Some(format!(
+                        "{} item(s) failed to publish in the last sync",
+                        stats.failed
+                    )));
+                } else {
+                    self.set_error(None);
+                }
+                Ok(stats)
             }
             Err(err) => {
                 tracing::warn!("federation sync failed: {err}");
                 self.set_error(Some(format!("sync failed: {err}")));
+                Err(anyhow::anyhow!("sync failed: {err}"))
             }
         }
     }
 
+    fn record_sync_success(&self, stats: SyncStats) {
+        *lock(&self.last_sync) = Some(format!(
+            "{} (+{} ~{} −{}, unchanged {}, failed {})",
+            now_iso(),
+            stats.added,
+            stats.updated,
+            stats.removed,
+            stats.unchanged,
+            stats.failed
+        ));
+    }
+
+    fn record_publish_success(&self, sync_stats: SyncStats, publish_stats: PublishStats) {
+        *lock(&self.last_sync) = Some(format!(
+            "{} (+{} ~{} −{}, unchanged {}, failed {}; republished {} records, {} keys, remote nodes {})",
+            now_iso(),
+            sync_stats.added,
+            sync_stats.updated,
+            sync_stats.removed,
+            sync_stats.unchanged,
+            sync_stats.failed,
+            publish_stats.records,
+            publish_stats.keys,
+            publish_stats.remote_nodes,
+        ));
+        self.set_error(None);
+    }
+
     /// Everything the regular player shows, as DHT item specs: non-hidden
     /// artists, releases and tracks (a track also hides with its release).
-    async fn collect_specs(&self) -> Result<Vec<ItemSpec>> {
+    async fn collect_specs(self: &Arc<Self>) -> Result<Vec<ItemSpec>> {
         let pool = self.pool().await?;
         let mut specs = Vec::new();
 
-        let artists =
-            sqlx::query("SELECT id, name FROM furumusic__artist WHERE is_hidden = false")
-                .fetch_all(&pool)
-                .await?;
+        let artists = sqlx::query("SELECT id, name FROM furumusic__artist WHERE is_hidden = false")
+            .fetch_all(&pool)
+            .await?;
         for row in &artists {
             let id: i64 = row.get(0);
             specs.push(ItemSpec {
@@ -309,9 +369,14 @@ impl Federation {
                 kind: ItemKind::Artist,
                 name: row.get(1),
                 artist_names: Vec::new(),
+                featured_artist_names: Vec::new(),
                 year: None,
                 release_type: None,
+                release_title: None,
+                track_number: None,
+                disc_number: None,
                 duration_seconds: None,
+                content_id: None,
             });
         }
 
@@ -343,52 +408,150 @@ impl Federation {
                 kind: ItemKind::Release,
                 name: row.get(1),
                 artist_names: artists_of_release.remove(&id).unwrap_or_default(),
+                featured_artist_names: Vec::new(),
                 year: row.get(2),
                 release_type: row.get(3),
+                release_title: None,
+                track_number: None,
+                disc_number: None,
                 duration_seconds: None,
+                content_id: None,
             });
         }
 
         let track_artists = sqlx::query(
-            "SELECT ta.track_id, a.name FROM furumusic__track_artist ta
+            "SELECT ta.track_id, a.name, ta.role FROM furumusic__track_artist ta
              JOIN furumusic__artist a ON a.id = ta.artist_id
              WHERE ta.role IN ('main', 'featuring')
-             ORDER BY ta.track_id, ta.position",
+             ORDER BY ta.track_id,
+                      CASE ta.role WHEN 'main' THEN 0 ELSE 1 END,
+                      ta.position",
         )
         .fetch_all(&pool)
         .await?;
         let mut artists_of_track: std::collections::HashMap<i64, Vec<String>> = Default::default();
+        let mut featured_of_track: std::collections::HashMap<i64, Vec<String>> = Default::default();
         for row in &track_artists {
-            artists_of_track
-                .entry(row.get(0))
-                .or_default()
-                .push(row.get(1));
+            let id: i64 = row.get(0);
+            let name: String = row.get(1);
+            if row.get::<String, _>(2) == "featuring" {
+                featured_of_track.entry(id).or_default().push(name);
+            } else {
+                artists_of_track.entry(id).or_default().push(name);
+            }
         }
         let tracks = sqlx::query(
-            "SELECT t.id, t.title, COALESCE(t.year, r.year), t.duration_seconds
+            "SELECT t.id, t.title, COALESCE(t.year, r.year), t.duration_seconds,
+                    r.title, r.release_type, t.track_number, t.disc_number,
+                    t.audio_file_id, m.file_path, m.sha256_hash, c.content_id
              FROM furumusic__track t
              JOIN furumusic__release r ON r.id = t.release_id
+             JOIN furumusic__media_file m ON m.id = t.audio_file_id
+             LEFT JOIN furumusic__federation_content_id_cache c
+                    ON c.media_file_id = m.id AND c.sha256_hash = m.sha256_hash
              WHERE t.is_hidden = false AND r.is_hidden = false",
         )
         .fetch_all(&pool)
         .await?;
+        let storage_dir = lock(&self.storage_dir).clone();
+        let mut content_hash_jobs = Vec::new();
         for row in &tracks {
             let id: i64 = row.get(0);
             let duration: f64 = row.get(3);
+            let media_file_id: i64 = row.get(8);
+            let file_path: String = row.get(9);
+            let sha256_hash: String = row.get(10);
+            let cached_content_id: Option<String> = row.get(11);
+            let content_id = cached_content_id
+                .or_else(|| self.cached_content_id_for_media(media_file_id, &sha256_hash));
+            if content_id.is_none()
+                && !storage_dir.trim().is_empty()
+                && self.mark_content_hash_pending(media_file_id)
+            {
+                content_hash_jobs.push(ContentHashJob {
+                    media_file_id,
+                    sha256_hash,
+                    file_path,
+                });
+            }
             specs.push(ItemSpec {
                 local_key: format!("track:{id}"),
                 kind: ItemKind::Track,
                 name: row.get(1),
                 artist_names: artists_of_track.remove(&id).unwrap_or_default(),
+                featured_artist_names: featured_of_track.remove(&id).unwrap_or_default(),
                 year: row.get(2),
-                release_type: None,
+                release_type: row.get(5),
+                release_title: Some(row.get(4)),
+                track_number: row.get(6),
+                disc_number: row.get(7),
                 duration_seconds: (duration > 0.0).then_some(duration),
+                content_id,
             });
         }
+        self.spawn_content_warmer(pool.clone(), storage_dir, content_hash_jobs);
 
         Ok(specs)
     }
 
+    fn cached_content_id_for_media(&self, media_file_id: i64, sha256_hash: &str) -> Option<String> {
+        if let Some((cached_hash, content_id)) = lock(&self.content_cache).get(&media_file_id)
+            && cached_hash == sha256_hash
+        {
+            return Some(content_id.clone());
+        }
+        None
+    }
+
+    fn mark_content_hash_pending(&self, media_file_id: i64) -> bool {
+        lock(&self.content_pending).insert(media_file_id)
+    }
+
+    fn spawn_content_warmer(
+        self: &Arc<Self>,
+        pool: PgPool,
+        storage_dir: String,
+        jobs: Vec<ContentHashJob>,
+    ) {
+        if jobs.is_empty() {
+            return;
+        }
+        let fed = Arc::clone(self);
+        tokio::spawn(async move {
+            let total = jobs.len();
+            let mut stored = 0usize;
+            for job in jobs {
+                let job_storage_dir = storage_dir.clone();
+                let job_file_path = job.file_path.clone();
+                let content_id = tokio::task::spawn_blocking(move || {
+                    audio_content_id(&job_storage_dir, &job_file_path)
+                })
+                .await
+                .ok()
+                .flatten();
+                lock(&fed.content_pending).remove(&job.media_file_id);
+                if let Some(content_id) = content_id {
+                    lock(&fed.content_cache).insert(
+                        job.media_file_id,
+                        (job.sha256_hash.clone(), content_id.clone()),
+                    );
+                    if let Err(err) =
+                        persist_content_id(&pool, job.media_file_id, &job.sha256_hash, &content_id)
+                            .await
+                    {
+                        tracing::warn!(
+                            media_file_id = job.media_file_id,
+                            "federation content-id cache write failed: {err:#}"
+                        );
+                    } else {
+                        stored += 1;
+                    }
+                }
+            }
+            tracing::info!(total, stored, "federation content-id cache warm finished");
+        });
+    }
+
     /// Live status for the admin page.
     pub async fn status(&self) -> Value {
         let guard = self.running.lock().await;
@@ -446,6 +609,41 @@ impl Federation {
     }
 }
 
+async fn persist_content_id(
+    pool: &PgPool,
+    media_file_id: i64,
+    sha256_hash: &str,
+    content_id: &str,
+) -> Result<()> {
+    sqlx::query(
+        "INSERT INTO furumusic__federation_content_id_cache
+         (media_file_id, sha256_hash, content_id, updated_at)
+         VALUES ($1, $2, $3, $4)
+         ON CONFLICT (media_file_id) DO UPDATE SET
+            sha256_hash = EXCLUDED.sha256_hash,
+            content_id = EXCLUDED.content_id,
+            updated_at = EXCLUDED.updated_at",
+    )
+    .bind(media_file_id)
+    .bind(sha256_hash)
+    .bind(content_id)
+    .bind(now_iso())
+    .execute(pool)
+    .await?;
+    Ok(())
+}
+
+fn audio_content_id(storage_dir: &str, file_path: &str) -> Option<String> {
+    if storage_dir.trim().is_empty() {
+        return None;
+    }
+    let path = crate::media_paths::resolve_media_file_path(storage_dir, file_path);
+    let mut file = std::fs::File::open(path).ok()?;
+    let mut hasher = blake3::Hasher::new();
+    std::io::copy(&mut file, &mut hasher).ok()?;
+    Some(format!("b3:{}", hasher.finalize().to_hex()))
+}
+
 async fn stop_running(running: Option<Running>) {
     let Some(running) = running else { return };
     for task in &running.tasks {

src/federation/serve.rs

@@ -101,6 +101,8 @@ struct CatalogTrack {
     track_number: Option<i32>,
     disc_number: Option<i32>,
     duration_seconds: Option<f64>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    content_id: Option<String>,
     item_id: String,
 }
 
@@ -150,7 +152,10 @@ async fn read_line<R: AsyncRead + Unpin>(reader: &mut R) -> Result<Vec<u8>> {
     }
 }
 
-async fn write_line<W: AsyncWriteExt + Unpin>(writer: &mut W, value: &impl Serialize) -> Result<()> {
+async fn write_line<W: AsyncWriteExt + Unpin>(
+    writer: &mut W,
+    value: &impl Serialize,
+) -> Result<()> {
     let mut line = serde_json::to_vec(value)?;
     line.push(b'\n');
     writer.write_all(&line).await?;
@@ -186,7 +191,10 @@ fn guess_mime(path: &Path) -> &'static str {
 }
 
 /// Reads an image media file from disk, bounded by [`MAX_IMAGE_BYTES`].
-async fn read_image(storage_dir: &str, media: Option<(String, String)>) -> Option<(Vec<u8>, String)> {
+async fn read_image(
+    storage_dir: &str,
+    media: Option<(String, String)>,
+) -> Option<(Vec<u8>, String)> {
     let (file_path, mime) = media?;
     let path = resolve_media_path(storage_dir, &file_path);
     let size = tokio::fs::metadata(&path).await.ok()?.len();
@@ -367,7 +375,9 @@ async fn serve_audio_one(
         Some(item_id) => match resolve_track_id(&pool, &own, item_id).await {
             Ok(Some(track_id)) => track_id,
             Ok(None) => return refuse_audio(stream, "track not found in the library").await,
-            Err(err) => return refuse_audio(stream, &format!("library lookup failed: {err:#}")).await,
+            Err(err) => {
+                return refuse_audio(stream, &format!("library lookup failed: {err:#}")).await;
+            }
         },
         None => return refuse_audio(stream, "malformed item_id").await,
     };
@@ -378,7 +388,9 @@ async fn serve_audio_one(
     let path = resolve_media_path(&storage_dir, &file_path);
     let mut file = match tokio::fs::File::open(&path).await {
         Ok(file) => file,
-        Err(err) => return refuse_audio(stream, &format!("audio file is not readable: {err}")).await,
+        Err(err) => {
+            return refuse_audio(stream, &format!("audio file is not readable: {err}")).await;
+        }
     };
     let total_size = file.metadata().await?.len();
     let offset = request.offset.min(total_size);
@@ -395,10 +407,17 @@ async fn serve_audio_one(
     };
     let (cover, artist_image) = if request.want_cover {
         (
-            read_image(&storage_dir, track_cover_file(&pool, track_id).await.ok().flatten()).await,
             read_image(
                 &storage_dir,
-                track_artist_image_file(&pool, track_id).await.ok().flatten(),
+                track_cover_file(&pool, track_id).await.ok().flatten(),
+            )
+            .await,
+            read_image(
+                &storage_dir,
+                track_artist_image_file(&pool, track_id)
+                    .await
+                    .ok()
+                    .flatten(),
             )
             .await,
         )
@@ -511,7 +530,10 @@ async fn serve_catalog_one(
                     artist: None,
                 },
             };
-            stream.send.write_all(&serde_json::to_vec(&response)?).await?;
+            stream
+                .send
+                .write_all(&serde_json::to_vec(&response)?)
+                .await?;
         }
         Some(want @ ("artist_image" | "release_cover")) => {
             let media = if want == "release_cover" {
@@ -549,7 +571,10 @@ async fn serve_catalog_one(
                 error: Some(format!("unknown request kind '{other}'")),
                 artist: None,
             };
-            stream.send.write_all(&serde_json::to_vec(&response)?).await?;
+            stream
+                .send
+                .write_all(&serde_json::to_vec(&response)?)
+                .await?;
         }
     }
     stream.send.finish()?;
@@ -589,32 +614,36 @@ async fn build_catalog(pool: &PgPool, own: &EndpointId, artist: &str) -> Result<
     for release_row in release_rows {
         let release_id: i64 = release_row.get(0);
         let track_rows = sqlx::query(
-            "SELECT id, title, track_number, disc_number, duration_seconds
-             FROM furumusic__track
-             WHERE release_id = $1 AND is_hidden = false
-             ORDER BY disc_number NULLS FIRST, track_number NULLS LAST, title",
+            "SELECT t.id, t.title, t.track_number, t.disc_number, t.duration_seconds,
+                    c.content_id
+             FROM furumusic__track t
+             JOIN furumusic__media_file m ON m.id = t.audio_file_id
+             LEFT JOIN furumusic__federation_content_id_cache c
+                    ON c.media_file_id = m.id AND c.sha256_hash = m.sha256_hash
+             WHERE t.release_id = $1 AND t.is_hidden = false
+             ORDER BY t.disc_number NULLS FIRST, t.track_number NULLS LAST, t.title",
         )
         .bind(release_id)
         .fetch_all(pool)
         .await?;
+        let mut tracks = Vec::with_capacity(track_rows.len());
+        for row in track_rows {
+            let track_id: i64 = row.get(0);
+            let duration: f64 = row.get(4);
+            tracks.push(CatalogTrack {
+                title: row.get(1),
+                track_number: row.get(2),
+                disc_number: row.get(3),
+                duration_seconds: (duration > 0.0).then_some(duration),
+                content_id: row.get(5),
+                item_id: item_id_of(own, track_id),
+            });
+        }
         releases.push(CatalogRelease {
             title: release_row.get(1),
             release_type: release_row.get(2),
             year: release_row.get(3),
-            tracks: track_rows
-                .into_iter()
-                .map(|row| {
-                    let track_id: i64 = row.get(0);
-                    let duration: f64 = row.get(4);
-                    CatalogTrack {
-                        title: row.get(1),
-                        track_number: row.get(2),
-                        disc_number: row.get(3),
-                        duration_seconds: (duration > 0.0).then_some(duration),
-                        item_id: item_id_of(own, track_id),
-                    }
-                })
-                .collect(),
+            tracks,
         });
     }
 

src/federation/storage.rs

@@ -0,0 +1,349 @@
+use std::str::FromStr;
+
+use async_trait::async_trait;
+use music_dht::{
+    DhtKey, EndpointId, LibraryItem, MAX_RECORDS_PER_RESPONSE, MusicDhtError, MusicDhtStorage,
+    NodeContact, NodeId, SecretKey, StoreDecision, StoredRecord, decide_store,
+};
+use sqlx::{PgPool, Row as _};
+
+const IDENTITY_NAME: &str = "default";
+
+const SCHEMA: &[&str] = &[
+    "CREATE TABLE IF NOT EXISTS furumusic__federation_identity (
+        name        TEXT PRIMARY KEY,
+        secret_key  BYTEA NOT NULL,
+        created_at  TEXT NOT NULL,
+        updated_at  TEXT NOT NULL
+    )",
+    "CREATE TABLE IF NOT EXISTS furumusic__federation_local_item (
+        id              BYTEA PRIMARY KEY,
+        normalized_name TEXT NOT NULL,
+        revision        BIGINT NOT NULL,
+        deleted         BOOLEAN NOT NULL DEFAULT false,
+        updated_at_ms   BIGINT NOT NULL,
+        payload         BYTEA NOT NULL
+    )",
+    "CREATE INDEX IF NOT EXISTS idx_furumusic_federation_local_item_normalized_name
+        ON furumusic__federation_local_item(normalized_name)",
+    "CREATE TABLE IF NOT EXISTS furumusic__federation_dht_record (
+        dht_key          BYTEA NOT NULL,
+        item_id          BYTEA NOT NULL,
+        owner_peer_id    TEXT NOT NULL,
+        payload          BYTEA NOT NULL,
+        revision         BIGINT NOT NULL,
+        deleted          BOOLEAN NOT NULL,
+        expires_at_ms    BIGINT NOT NULL,
+        PRIMARY KEY (dht_key, item_id, owner_peer_id)
+    )",
+    "CREATE INDEX IF NOT EXISTS idx_furumusic_federation_dht_record_expires_at
+        ON furumusic__federation_dht_record(expires_at_ms)",
+    "CREATE TABLE IF NOT EXISTS furumusic__federation_known_peer (
+        peer_id       TEXT PRIMARY KEY,
+        node_id       BYTEA NOT NULL,
+        ticket        TEXT NOT NULL,
+        last_seen_ms  BIGINT NOT NULL
+    )",
+    "CREATE TABLE IF NOT EXISTS furumusic__federation_content_id_cache (
+        media_file_id  BIGINT PRIMARY KEY,
+        sha256_hash    TEXT NOT NULL,
+        content_id     TEXT NOT NULL,
+        updated_at     TEXT NOT NULL
+    )",
+    "CREATE INDEX IF NOT EXISTS idx_furumusic_federation_content_id_cache_content_id
+        ON furumusic__federation_content_id_cache(content_id)",
+];
+
+#[derive(Debug, Clone)]
+pub struct PostgresFederationStorage {
+    pool: PgPool,
+}
+
+impl PostgresFederationStorage {
+    pub async fn new(pool: PgPool) -> music_dht::Result<Self> {
+        let storage = Self { pool };
+        storage.ensure_schema().await?;
+        Ok(storage)
+    }
+
+    pub async fn load_or_create_secret_key(&self) -> music_dht::Result<SecretKey> {
+        if let Some(bytes) = sqlx::query_scalar::<_, Vec<u8>>(
+            "SELECT secret_key FROM furumusic__federation_identity WHERE name = $1",
+        )
+        .bind(IDENTITY_NAME)
+        .fetch_optional(&self.pool)
+        .await
+        .map_err(db_error)?
+        {
+            return secret_from_bytes(bytes);
+        }
+
+        let key = SecretKey::generate();
+        let key_bytes = key.to_bytes();
+        let now = now_iso();
+        let inserted = sqlx::query(
+            "INSERT INTO furumusic__federation_identity
+             (name, secret_key, created_at, updated_at)
+             VALUES ($1, $2, $3, $4)
+             ON CONFLICT (name) DO NOTHING",
+        )
+        .bind(IDENTITY_NAME)
+        .bind(key_bytes.as_slice())
+        .bind(&now)
+        .bind(&now)
+        .execute(&self.pool)
+        .await
+        .map_err(db_error)?
+        .rows_affected();
+        if inserted == 1 {
+            return Ok(key);
+        }
+
+        let bytes = sqlx::query_scalar::<_, Vec<u8>>(
+            "SELECT secret_key FROM furumusic__federation_identity WHERE name = $1",
+        )
+        .bind(IDENTITY_NAME)
+        .fetch_one(&self.pool)
+        .await
+        .map_err(db_error)?;
+        secret_from_bytes(bytes)
+    }
+
+    async fn ensure_schema(&self) -> music_dht::Result<()> {
+        for sql in SCHEMA {
+            sqlx::query(sql)
+                .execute(&self.pool)
+                .await
+                .map_err(db_error)?;
+        }
+        Ok(())
+    }
+}
+
+#[async_trait]
+impl MusicDhtStorage for PostgresFederationStorage {
+    async fn upsert_local_item(&self, item: &LibraryItem) -> music_dht::Result<()> {
+        let payload = postcard::to_stdvec(item).map_err(db_error)?;
+        sqlx::query(
+            "INSERT INTO furumusic__federation_local_item
+             (id, normalized_name, revision, deleted, updated_at_ms, payload)
+             VALUES ($1, $2, $3, $4, $5, $6)
+             ON CONFLICT (id) DO UPDATE SET
+                normalized_name = EXCLUDED.normalized_name,
+                revision = EXCLUDED.revision,
+                deleted = EXCLUDED.deleted,
+                updated_at_ms = EXCLUDED.updated_at_ms,
+                payload = EXCLUDED.payload",
+        )
+        .bind(item.id.as_bytes().as_slice())
+        .bind(&item.normalized_name)
+        .bind(item.revision as i64)
+        .bind(item.deleted)
+        .bind(item.updated_at_ms as i64)
+        .bind(payload)
+        .execute(&self.pool)
+        .await
+        .map_err(db_error)?;
+        Ok(())
+    }
+
+    async fn list_local_items(&self, include_deleted: bool) -> music_dht::Result<Vec<LibraryItem>> {
+        let rows = sqlx::query(
+            "SELECT payload
+             FROM furumusic__federation_local_item
+             WHERE $1 OR deleted = false
+             ORDER BY normalized_name",
+        )
+        .bind(include_deleted)
+        .fetch_all(&self.pool)
+        .await
+        .map_err(db_error)?;
+        Ok(rows
+            .into_iter()
+            .filter_map(|row| postcard::from_bytes::<LibraryItem>(&row.get::<Vec<u8>, _>(0)).ok())
+            .collect())
+    }
+
+    async fn store_dht_record(&self, key: DhtKey, record: StoredRecord) -> music_dht::Result<bool> {
+        let mut conn = self.pool.acquire().await.map_err(db_error)?;
+        store_record_in_conn(&mut conn, &key, &record).await
+    }
+
+    async fn store_dht_records(
+        &self,
+        entries: Vec<(DhtKey, StoredRecord)>,
+    ) -> music_dht::Result<Vec<bool>> {
+        let mut tx = self.pool.begin().await.map_err(db_error)?;
+        let mut stored = Vec::with_capacity(entries.len());
+        for (key, record) in &entries {
+            stored.push(store_record_in_conn(&mut tx, key, record).await?);
+        }
+        tx.commit().await.map_err(db_error)?;
+        Ok(stored)
+    }
+
+    async fn dht_records_by_key(
+        &self,
+        key: DhtKey,
+        now_ms: u64,
+    ) -> music_dht::Result<Vec<StoredRecord>> {
+        let rows = sqlx::query(
+            "SELECT payload
+             FROM furumusic__federation_dht_record
+             WHERE dht_key = $1 AND expires_at_ms > $2
+             ORDER BY expires_at_ms DESC, item_id
+             LIMIT $3",
+        )
+        .bind(key.as_bytes().as_slice())
+        .bind(now_ms as i64)
+        .bind(MAX_RECORDS_PER_RESPONSE as i64)
+        .fetch_all(&self.pool)
+        .await
+        .map_err(db_error)?;
+        Ok(rows
+            .into_iter()
+            .filter_map(|row| postcard::from_bytes::<StoredRecord>(&row.get::<Vec<u8>, _>(0)).ok())
+            .collect())
+    }
+
+    async fn delete_expired_records(&self, now_ms: u64) -> music_dht::Result<usize> {
+        let result =
+            sqlx::query("DELETE FROM furumusic__federation_dht_record WHERE expires_at_ms <= $1")
+                .bind(now_ms as i64)
+                .execute(&self.pool)
+                .await
+                .map_err(db_error)?;
+        Ok(result.rows_affected() as usize)
+    }
+
+    async fn upsert_known_peer(&self, contact: &NodeContact) -> music_dht::Result<()> {
+        sqlx::query(
+            "INSERT INTO furumusic__federation_known_peer
+             (peer_id, node_id, ticket, last_seen_ms)
+             VALUES ($1, $2, $3, $4)
+             ON CONFLICT (peer_id) DO UPDATE SET
+                node_id = EXCLUDED.node_id,
+                ticket = EXCLUDED.ticket,
+                last_seen_ms = EXCLUDED.last_seen_ms",
+        )
+        .bind(contact.peer_id.to_string())
+        .bind(contact.node_id.as_bytes().as_slice())
+        .bind(&contact.ticket)
+        .bind(contact.last_seen_ms as i64)
+        .execute(&self.pool)
+        .await
+        .map_err(db_error)?;
+        Ok(())
+    }
+
+    async fn delete_known_peer(&self, peer_id: EndpointId) -> music_dht::Result<()> {
+        sqlx::query("DELETE FROM furumusic__federation_known_peer WHERE peer_id = $1")
+            .bind(peer_id.to_string())
+            .execute(&self.pool)
+            .await
+            .map_err(db_error)?;
+        Ok(())
+    }
+
+    async fn load_known_peers(&self) -> music_dht::Result<Vec<NodeContact>> {
+        let rows = sqlx::query(
+            "SELECT peer_id, node_id, ticket, last_seen_ms
+             FROM furumusic__federation_known_peer",
+        )
+        .fetch_all(&self.pool)
+        .await
+        .map_err(db_error)?;
+        let mut contacts = Vec::new();
+        for row in rows {
+            let peer_id: String = row.get(0);
+            let node_id: Vec<u8> = row.get(1);
+            let ticket: String = row.get(2);
+            let last_seen_ms: i64 = row.get(3);
+            let Ok(peer_id) = EndpointId::from_str(&peer_id) else {
+                continue;
+            };
+            let Ok(node_id) = <[u8; 32]>::try_from(node_id.as_slice()) else {
+                continue;
+            };
+            contacts.push(NodeContact {
+                node_id: NodeId::from_bytes(node_id),
+                peer_id,
+                ticket,
+                last_seen_ms: last_seen_ms as u64,
+            });
+        }
+        Ok(contacts)
+    }
+}
+
+fn now_iso() -> String {
+    chrono::Utc::now().format("%Y-%m-%dT%H:%M:%SZ").to_string()
+}
+
+fn secret_from_bytes(bytes: Vec<u8>) -> music_dht::Result<SecretKey> {
+    let bytes: [u8; 32] = bytes
+        .as_slice()
+        .try_into()
+        .map_err(|_| MusicDhtError::Database("stored federation identity is corrupted".into()))?;
+    Ok(SecretKey::from_bytes(&bytes))
+}
+
+/// Applies one validated record following the revision/tombstone rules.
+/// Returns `true` if the record was written or refreshed. Runs against a
+/// pooled connection or an open transaction.
+async fn store_record_in_conn(
+    conn: &mut sqlx::PgConnection,
+    key: &DhtKey,
+    record: &StoredRecord,
+) -> music_dht::Result<bool> {
+    let existing = sqlx::query(
+        "SELECT revision, deleted, expires_at_ms
+         FROM furumusic__federation_dht_record
+         WHERE dht_key = $1 AND item_id = $2 AND owner_peer_id = $3",
+    )
+    .bind(key.as_bytes().as_slice())
+    .bind(record.item.id.as_bytes().as_slice())
+    .bind(record.item.owner.to_string())
+    .fetch_optional(&mut *conn)
+    .await
+    .map_err(db_error)?
+    .map(|row| {
+        (
+            row.get::<i64, _>(0) as u64,
+            row.get::<bool, _>(1),
+            row.get::<i64, _>(2) as u64,
+        )
+    });
+
+    match decide_store(existing, record) {
+        StoreDecision::Ignore => return Ok(false),
+        StoreDecision::Write | StoreDecision::RefreshExpiry(_) => {}
+    }
+
+    let payload = postcard::to_stdvec(record).map_err(db_error)?;
+    sqlx::query(
+        "INSERT INTO furumusic__federation_dht_record
+         (dht_key, item_id, owner_peer_id, payload, revision, deleted, expires_at_ms)
+         VALUES ($1, $2, $3, $4, $5, $6, $7)
+         ON CONFLICT (dht_key, item_id, owner_peer_id) DO UPDATE SET
+            payload = EXCLUDED.payload,
+            revision = EXCLUDED.revision,
+            deleted = EXCLUDED.deleted,
+            expires_at_ms = EXCLUDED.expires_at_ms",
+    )
+    .bind(key.as_bytes().as_slice())
+    .bind(record.item.id.as_bytes().as_slice())
+    .bind(record.item.owner.to_string())
+    .bind(payload)
+    .bind(record.item.revision as i64)
+    .bind(record.item.deleted)
+    .bind(record.expires_at_ms as i64)
+    .execute(&mut *conn)
+    .await
+    .map_err(db_error)?;
+    Ok(true)
+}
+
+fn db_error(err: impl std::fmt::Display) -> MusicDhtError {
+    MusicDhtError::Database(err.to_string())
+}

src/main.rs

@@ -3,6 +3,7 @@ mod agent;
 mod api;
 mod auth;
 mod config;
+mod federation;
 mod i18n;
 mod jobs;
 mod lastfm;
@@ -12,7 +13,6 @@ mod music;
 mod oidc;
 mod player;
 mod scheduler;
-mod federation;
 mod torrents;
 mod user;