Retire offline node claims with equal network-wide cleanup rights

Offline devices reserved names and IPv4 addresses indefinitely, leaving stale
members in the device history. Give every authenticated network participant
the same right to retire another device's observed signed claim without an
owner, quorum, permanent identity ban or secret change.

Add a separately signed retirement containing the target's original signed
claim as proof. Verify both signatures and network scopes, retain the strongest
proved cutoff per target with deterministic ties, and suppress claim versions
at or below it in membership, hostname ownership and IPv4 allocation. Keep the
old signed records and range agreement, and retain markers after a newer claim
returns so old replicas cannot resurrect obsolete reservations. A returning
device signs a newer claim, allocates against current holders and resets its
previous hostname priority rather than taking a reused name with an old time.

Commit local retirement and the requester's author counter atomically before
announcing it; receivers persist proofs before applying them. Bound history to
1024 targets by default, reject additional targets without evicting protection,
and treat corrupt or over-limit mandatory storage as an explicit error. Repeat
bounded marker batches with a per-session rotating cursor so queue pressure
cannot indefinitely starve later markers. Exclude retired claims and cached
hints from history-derived discovery without preventing a fresh authenticated
device from returning.

Expose Agent::forget_node through the shared local control API. CLI command
tsng network forget-node accepts exact network names, full ids or unique id
prefixes, and exact node hostnames, ids, prefixes or overlay IPv4 addresses.
Ambiguous selections change nothing. Recheck the observed version and refuse
self, online nodes, the selected exit node and absent or changed claims.
Add Forget with an identity confirmation to offline tray device rows. Widen
Show devices to 1440x640 with an 800x400 minimum to fit its contents.

Control ALPN/version advances to tsunagi/ctrl/7 and local IPC to 21; upgrade
all peers and restart the agent with matching CLI/tray clients. Data ALPN 5,
network identity derivation, handshake encoding and existing record signing
bytes remain unchanged. SQLite schema 9 adds retirement storage while retaining
identity, secrets, settings and signed claims. Document behavior and limits.

Validation on Linux through nix develop:
- cargo fmt --all -- --check
- cargo clippy --locked --workspace --all-targets -- -D warnings
- cargo test --locked --workspace --all-targets: 519 passed, 2 existing ignored
  tests; inherited TSUNAGI_CONTROL_SOCKET and TSUNAGI_CONTROL_GROUP were unset
- git diff --check and the built CLI forget-node help

Tests use real iroh authentication and SQLite. Cover restart, stale-replica
recovery, equal rights and network isolation, hostname reuse and return, twelve
marker batches through a two-message queue, malformed signatures and proofs,
invented future cutoffs, deterministic merge, capacity, migration and injected
counter-write rollback, selectors and cleanup through two real CLI processes.
Earlier iterations caught a private test API, a collapsible tray conditional
and a crash-based CLI test waiting for QUIC's idle timeout; corrected before
the final successful suite. Manual tray rendering, macOS/Windows, privileged
TUNs and public-network traversal were not run. The requested RC tag is
v0.1.0-rc.31; no push was requested.

crates/tsunagi-core/src/ipc/mod.rs

@@ -171,6 +171,15 @@ pub fn default_control_socket_path() -> PathBuf {
 #[derive(Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[non_exhaustive]
 pub enum Request {
+    /// Retire the selected offline member's observed claim.
+    ForgetNode {
+        /// Exact public network id.
+        network_id: String,
+        /// Exact device identity selected by the client.
+        peer: String,
+        /// Claim version displayed when the user selected the node.
+        expected_version: u64,
+    },
     /// Replace one network's ordered local data-plane selection.
     SetProtocols {
         /// Public network identifier.
@@ -262,6 +271,14 @@ pub enum Request {
 impl std::fmt::Debug for Request {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
+            Request::ForgetNode {
+                network_id,
+                peer,
+                expected_version,
+            } => write!(
+                f,
+                "ForgetNode {{ {network_id}, peer: {peer}, version: {expected_version} }}"
+            ),
             Request::SetProtocols {
                 network_id,
                 protocols,
@@ -300,6 +317,8 @@ impl std::fmt::Debug for Request {
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[non_exhaustive]
 pub enum Response {
+    /// An observed offline claim was durably retired.
+    NodeForgotten(ForgottenNodeReport),
     /// Accepted ordered protocol selection.
     Protocols(Vec<String>),
     /// A status report.
@@ -328,6 +347,141 @@ pub enum Response {
     Error(String),
 }
 
+/// The durable result of an offline-node cleanup.
+#[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
+pub struct ForgottenNodeReport {
+    /// Selected device identity.
+    pub peer: String,
+    /// The retired claim version, not a future-version ban.
+    pub record_version: u64,
+    /// Peers to which cleanup was immediately queued.
+    pub peers_told: u32,
+}
+
+/// Resolves a node by exact hostname, full id, unique id prefix or overlay IPv4.
+/// Ambiguity is reported with names and full ids and never guessed.
+pub fn resolve_node<'a>(
+    network: &'a NetworkReport,
+    selector: &str,
+) -> std::result::Result<&'a MemberReport, String> {
+    let selector = selector.trim();
+    if selector.is_empty() {
+        return Err("select a node by name, id or IPv4 address".into());
+    }
+    if let Some(member) = network.members.iter().find(|m| m.endpoint_id == selector) {
+        return Ok(member);
+    }
+    let prefix = selector.trim_end_matches('…');
+    let matches: Vec<_> = network
+        .members
+        .iter()
+        .filter(|m| {
+            m.hostname.as_deref() == Some(selector)
+                || m.overlay_address_v4.as_deref() == Some(selector)
+                || (!prefix.is_empty() && m.endpoint_id.starts_with(prefix))
+        })
+        .collect();
+    match matches.as_slice() {
+        [one] => Ok(one),
+        [] => Err(format!(
+            "no signed node matches `{selector}` in `{}`",
+            network.name
+        )),
+        many => Err(format!(
+            "`{selector}` is ambiguous; use a full id or unique id prefix:\n{}",
+            many.iter()
+                .map(|m| format!(
+                    "  {}  {}  {}",
+                    m.hostname.as_deref().unwrap_or("unnamed"),
+                    m.endpoint_id,
+                    m.overlay_address_v4.as_deref().unwrap_or("no IPv4")
+                ))
+                .collect::<Vec<_>>()
+                .join("\n")
+        )),
+    }
+}
+
+/// Retires an exact selected claim; an online or changed target is rejected.
+pub async fn forget_node(
+    socket: &Path,
+    network: &str,
+    peer: &str,
+    expected_version: u64,
+) -> Result<ForgottenNodeReport> {
+    let request = Request::ForgetNode {
+        network_id: network.into(),
+        peer: peer.into(),
+        expected_version,
+    };
+    match exchange(socket, &request, EXCHANGE_TIMEOUT).await? {
+        Response::NodeForgotten(report) => Ok(report),
+        Response::Error(reason) => Err(Error::ForgetNode(reason)),
+        other => Err(Error::Storage(format!("unexpected response: {other:?}"))),
+    }
+}
+
+#[cfg(test)]
+mod node_selector_tests {
+    use super::*;
+
+    #[test]
+    fn exact_names_addresses_and_unique_prefixes_select_the_same_signed_node() {
+        let node = MemberReport {
+            endpoint_id: "abcdef01".into(),
+            hostname: Some("laptop".into()),
+            overlay_address_v4: Some("10.2.0.3".into()),
+            record_version: 42,
+            ..Default::default()
+        };
+        let network = NetworkReport {
+            name: "home".into(),
+            members: vec![node.clone()],
+            ..Default::default()
+        };
+        for selector in ["laptop", "10.2.0.3", "abcdef01", "abc…"] {
+            assert_eq!(resolve_node(&network, selector), Ok(&node));
+        }
+        for selector in ["", "LAPTOP", "missing"] {
+            assert!(resolve_node(&network, selector).is_err());
+        }
+    }
+
+    #[test]
+    fn collisions_between_names_addresses_and_prefixes_require_an_explicit_identity() {
+        let first = MemberReport {
+            endpoint_id: "abcdef01".into(),
+            hostname: Some("duplicate".into()),
+            overlay_address_v4: Some("10.2.0.3".into()),
+            ..Default::default()
+        };
+        let second = MemberReport {
+            endpoint_id: "abcdef02".into(),
+            hostname: Some("duplicate".into()),
+            overlay_address_v4: Some("10.2.0.3".into()),
+            ..Default::default()
+        };
+        let third = MemberReport {
+            endpoint_id: "12345678".into(),
+            hostname: Some("abc".into()),
+            ..Default::default()
+        };
+        let network = NetworkReport {
+            name: "home".into(),
+            members: vec![first.clone(), second, third],
+            ..Default::default()
+        };
+        for selector in ["duplicate", "10.2.0.3", "abc"] {
+            let result = resolve_node(&network, selector);
+            assert!(result.is_err_and(|error| error.contains("ambiguous")
+                && error.contains("abcdef01")
+                && error.contains("abcdef02")
+                && error.contains("duplicate")));
+        }
+        assert_eq!(resolve_node(&network, "abcdef01"), Ok(&first));
+    }
+}
+
 /// What happened when a network was stopped or started.
 #[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
 pub struct ActiveReport {
@@ -580,6 +734,8 @@ pub struct HostnameConflictReport {
 /// One member of the network, from signed state.
 #[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
 pub struct MemberReport {
+    /// Signed claim version used to reject stale cleanup requests.
+    pub record_version: u64,
     /// The member's device identity.
     pub endpoint_id: String,
     /// The IPv4 overlay address it claimed and signed for.
@@ -749,6 +905,15 @@ impl OverlayPeerReport {
 /// running and what they can report or change. That is what keeps this module
 /// free of any knowledge of them.
 pub trait ReportSource: Send + Sync + 'static {
+    /// Persists and announces a version-scoped node cleanup.
+    fn forget_node(
+        &self,
+        _network: String,
+        _peer: String,
+        _expected_version: u64,
+    ) -> BoxFuture<'_, std::result::Result<ForgottenNodeReport, String>> {
+        Box::pin(async { Err("this agent cannot forget node history".into()) })
+    }
     /// Saves and applies a local ordered protocol set for one network.
     fn set_protocols(
         &self,
@@ -886,7 +1051,7 @@ pub const EXCHANGE_TIMEOUT: Duration = Duration::from_secs(5);
 ///
 /// Bump it whenever [`Request`], [`Response`] or anything they contain
 /// changes shape.
-pub const CONTROL_PROTOCOL: u32 = u32::from_be_bytes([b'T', b'S', b'N', 20]);
+pub const CONTROL_PROTOCOL: u32 = u32::from_be_bytes([b'T', b'S', b'N', 21]);
 
 /// Reads one request off an accepted stream, answers it, writes the response.
 ///
@@ -910,6 +1075,14 @@ where
             }
         };
     let response = match request {
+        Request::ForgetNode {
+            network_id,
+            peer,
+            expected_version,
+        } => match source.forget_node(network_id, peer, expected_version).await {
+            Ok(report) => Response::NodeForgotten(report),
+            Err(reason) => Response::Error(reason),
+        },
         Request::SetProtocols {
             network_id,
             protocols,