fix(server): revoke viewer tokens on logout + stop logging chat content

Security follow-ups (audit 2026-05-30, both reviewed APPROVE):
- MEDIUM: viewer tokens were never blacklisted on logout, so a minted
  session-scoped viewer token stayed valid up to its 5-min TTL after the user
  logged out. Add a per-user ViewerTokenRegistry (Arc<Mutex<HashMap<sub,
  Vec<(token, expires_at)>>>>, prune-on-insert) on AppState; mint_viewer_token
  registers each token under the user sub; logout drains take_for_user(sub) and
  blacklists each via the existing token_blacklist. The viewer WS already calls
  is_revoked, so no WS change. Key chain user.user_id == ViewerClaims.sub ==
  registry key verified consistent. 8 new tests.
- LOW: relay chat logs now emit content length, not the chat body (support-chat
  can carry secrets/PII).
cargo fmt/clippy(-D warnings)/test green on GURU-5070 (37 agent + 61 server).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/src/api/auth_logout.rs

@@ -60,10 +60,27 @@ pub async fn logout(
     // Extract token from headers
     let token = extract_token_from_headers(request.headers())?;
 
-    // Add token to blacklist
+    // Add the login JWT to the blacklist.
     state.token_blacklist.revoke(&token).await;
 
-    info!("User {} logged out (token revoked)", user.username);
+    // Also revoke any outstanding session-scoped VIEWER tokens this user minted
+    // (CRITICAL #2). The login-JWT blacklist alone leaves a viewer token minted
+    // before logout valid for the rest of its 5-minute TTL, keeping a live
+    // viewer/remote-control plane open after logout. `user.user_id` is the `sub`
+    // the viewer tokens were registered under (the same claim stamped into them).
+    // The viewer WS already blacklist-checks the exact token string, so adding
+    // them here is sufficient — no WS change needed. take_for_user drains and
+    // clears the registry entry; expired tokens are pruned (not returned).
+    let viewer_tokens = state.viewer_tokens.take_for_user(&user.user_id);
+    let revoked_viewer_count = viewer_tokens.len();
+    for viewer_token in viewer_tokens {
+        state.token_blacklist.revoke(&viewer_token).await;
+    }
+
+    info!(
+        "User {} logged out (login token revoked, {} viewer token(s) revoked)",
+        user.username, revoked_viewer_count
+    );
 
     Ok(Json(LogoutResponse {
         message: "Logged out successfully".to_string(),
@@ -196,3 +213,74 @@ pub async fn cleanup_blacklist(
         remaining_count: remaining,
     }))
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::auth::{JwtConfig, TokenBlacklist, ViewerAccess, ViewerTokenRegistry};
+    use std::time::Duration;
+    use uuid::Uuid;
+
+    /// End-to-end (component-level) proof of CRITICAL #2: a viewer token minted
+    /// under a user, then revoked at logout via the registry drain, is rejected
+    /// by the SAME blacklist check the viewer WS runs (`is_revoked`).
+    ///
+    /// This exercises the real mint → register → logout-drain → blacklist path
+    /// without the HTTP/DB plumbing of the full handler. Uses local component
+    /// instances only (no process-global env), so it is parallel-safe.
+    #[tokio::test]
+    async fn logout_revokes_minted_viewer_token() {
+        let jwt = JwtConfig::new("test-secret-at-least-32-chars-long!!".to_string(), 24);
+        let registry = ViewerTokenRegistry::new();
+        let blacklist = TokenBlacklist::new();
+
+        let user_sub = Uuid::new_v4().to_string();
+        let session_id = Uuid::new_v4();
+        let tenant_id = Uuid::new_v4();
+
+        // Mint a viewer token and register it under the user (as mint_viewer_token does).
+        let viewer_token = jwt
+            .create_viewer_token(&user_sub, session_id, tenant_id, ViewerAccess::Control)
+            .unwrap();
+        registry.register(&user_sub, &viewer_token, Duration::from_secs(300));
+
+        // The viewer WS check (is_revoked) passes BEFORE logout — token is live.
+        assert!(!blacklist.is_revoked(&viewer_token).await);
+
+        // Logout drains the user's viewer tokens into the blacklist (handler logic).
+        for tok in registry.take_for_user(&user_sub) {
+            blacklist.revoke(&tok).await;
+        }
+
+        // After logout the same WS check now REJECTS the viewer token.
+        assert!(blacklist.is_revoked(&viewer_token).await);
+        // The token also remains a structurally valid viewer JWT (not expired),
+        // proving revocation — not natural expiry — is what blocks it.
+        assert!(jwt.validate_viewer_token(&viewer_token).is_ok());
+    }
+
+    /// A different user's logout must NOT revoke this user's viewer token.
+    #[tokio::test]
+    async fn logout_does_not_revoke_other_users_viewer_token() {
+        let jwt = JwtConfig::new("test-secret-at-least-32-chars-long!!".to_string(), 24);
+        let registry = ViewerTokenRegistry::new();
+        let blacklist = TokenBlacklist::new();
+
+        let user_a = Uuid::new_v4().to_string();
+        let user_b = Uuid::new_v4().to_string();
+        let session_id = Uuid::new_v4();
+        let tenant_id = Uuid::new_v4();
+
+        let token_b = jwt
+            .create_viewer_token(&user_b, session_id, tenant_id, ViewerAccess::ViewOnly)
+            .unwrap();
+        registry.register(&user_b, &token_b, Duration::from_secs(300));
+
+        // user_a logs out — drains only user_a's (empty) token set.
+        for tok in registry.take_for_user(&user_a) {
+            blacklist.revoke(&tok).await;
+        }
+
+        // user_b's token is untouched.
+        assert!(!blacklist.is_revoked(&token_b).await);
+    }
+}

server/src/api/sessions.rs

@@ -160,6 +160,18 @@ pub async fn mint_viewer_token(
             )
         })?;
 
+    // Register the minted token under the authenticated user's `sub` so logout
+    // can revoke it (CRITICAL #2): a viewer token minted before logout would
+    // otherwise stay valid for the rest of its 5-minute TTL. The registry prunes
+    // expired entries on insert, so it cannot grow unbounded. The token string
+    // is held transiently in memory (already handled server-side) and never
+    // logged. `user.user_id` is the `sub` claim stamped into the viewer token.
+    state.viewer_tokens.register(
+        &user.user_id,
+        &token,
+        std::time::Duration::from_secs(crate::auth::jwt::VIEWER_TOKEN_TTL_SECS as u64),
+    );
+
     tracing::info!(
         "User {} minted a {} viewer token for session {} (agent {})",
         user.username,

server/src/auth/mod.rs

@@ -7,10 +7,12 @@ pub mod agent_keys;
 pub mod jwt;
 pub mod password;
 pub mod token_blacklist;
+pub mod viewer_token_registry;
 
 pub use jwt::{Claims, JwtConfig, ViewerAccess};
 pub use password::{generate_random_password, hash_password, verify_password};
 pub use token_blacklist::TokenBlacklist;
+pub use viewer_token_registry::ViewerTokenRegistry;
 
 use axum::{
     extract::FromRequestParts,

server/src/auth/viewer_token_registry.rs

@@ -0,0 +1,186 @@
+//! Per-user registry of outstanding viewer tokens.
+//!
+//! Minted viewer tokens ([`super::jwt::ViewerClaims`]) are short-lived
+//! (`VIEWER_TOKEN_TTL_SECS`, 5 min) and session-scoped. The login-JWT blacklist
+//! revokes the LOGIN token on logout, but a viewer token minted before logout
+//! stays valid for the rest of its TTL — letting a just-logged-out user keep a
+//! live remote-control plane until natural expiry.
+//!
+//! This registry closes that gap with the least-invasive mechanism: when a
+//! viewer token is minted it is registered here under the minting user's `sub`;
+//! on logout, the user's outstanding viewer tokens are taken from the registry
+//! and added to the SAME exact-string blacklist the viewer WebSocket already
+//! checks (`relay::viewer_ws_handler` -> `TokenBlacklist::is_revoked`). No
+//! change to the WS path is required.
+//!
+//! Design notes:
+//! - The registry holds bearer-token strings transiently in memory. The server
+//!   already handles these tokens; they are never logged or otherwise exposed
+//!   by this module.
+//! - Entries are pruned-on-access (insert and take) by expiry, so the map can
+//!   never grow unbounded even if a user never logs out — expired viewer tokens
+//!   self-evict on the next operation that touches the map.
+//! - Locking is a poison-tolerant `std::sync::Mutex` (matching the rate-limiter
+//!   pattern: `lock().unwrap_or_else(|e| e.into_inner())`); a panic while the
+//!   lock is held must not wedge logout/mint. No `.unwrap()` on lock paths.
+
+use std::collections::HashMap;
+use std::sync::{Arc, Mutex};
+use std::time::{Duration, Instant};
+
+/// A single registered viewer token: the token string and the instant at which
+/// it expires (mint time + TTL).
+#[derive(Clone)]
+struct Entry {
+    token: String,
+    expires_at: Instant,
+}
+
+/// Per-user registry of outstanding (un-expired, un-revoked) viewer tokens.
+///
+/// Cheap to clone (shares the inner map via `Arc`), so it can live in
+/// `AppState` and be cloned with it like the other shared state.
+#[derive(Clone, Default)]
+pub struct ViewerTokenRegistry {
+    /// Map of user `sub` -> that user's outstanding viewer tokens.
+    inner: Arc<Mutex<HashMap<String, Vec<Entry>>>>,
+}
+
+impl ViewerTokenRegistry {
+    /// Create an empty registry.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Register a freshly minted viewer token under its owning user (`sub`),
+    /// expiring `ttl` from now.
+    ///
+    /// Prunes expired entries for this user on insert so the per-user vector and
+    /// the overall map stay bounded. The token string is stored verbatim (it is
+    /// the exact string the viewer WS blacklist-checks); it is never logged.
+    pub fn register(&self, sub: &str, token: &str, ttl: Duration) {
+        let now = Instant::now();
+        let expires_at = now + ttl;
+        let mut map = self.inner.lock().unwrap_or_else(|e| e.into_inner());
+
+        let entries = map.entry(sub.to_string()).or_default();
+        // Prune-on-insert: drop this user's already-expired tokens.
+        entries.retain(|e| e.expires_at > now);
+        entries.push(Entry {
+            token: token.to_string(),
+            expires_at,
+        });
+    }
+
+    /// Remove and return all currently-valid viewer tokens for `sub`.
+    ///
+    /// Expired tokens are pruned (not returned) — they are already invalid at
+    /// the JWT layer, so there is no value in blacklisting them. The user's
+    /// entry is cleared from the map regardless (taking everything out). Returns
+    /// an empty vec if the user has no registered tokens.
+    pub fn take_for_user(&self, sub: &str) -> Vec<String> {
+        let now = Instant::now();
+        let mut map = self.inner.lock().unwrap_or_else(|e| e.into_inner());
+
+        match map.remove(sub) {
+            Some(entries) => entries
+                .into_iter()
+                .filter(|e| e.expires_at > now)
+                .map(|e| e.token)
+                .collect(),
+            None => Vec::new(),
+        }
+    }
+
+    /// Number of users currently tracked (test/observability helper). Does not
+    /// prune; reflects the raw map size.
+    #[cfg(test)]
+    fn user_count(&self) -> usize {
+        let map = self.inner.lock().unwrap_or_else(|e| e.into_inner());
+        map.len()
+    }
+
+    /// Number of registered (un-pruned) tokens for a user (test helper).
+    #[cfg(test)]
+    fn token_count(&self, sub: &str) -> usize {
+        let map = self.inner.lock().unwrap_or_else(|e| e.into_inner());
+        map.get(sub).map(|v| v.len()).unwrap_or(0)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn register_then_take_returns_and_clears() {
+        let reg = ViewerTokenRegistry::new();
+        reg.register("user-a", "tok-1", Duration::from_secs(300));
+        reg.register("user-a", "tok-2", Duration::from_secs(300));
+
+        assert_eq!(reg.token_count("user-a"), 2);
+
+        let mut taken = reg.take_for_user("user-a");
+        taken.sort();
+        assert_eq!(taken, vec!["tok-1".to_string(), "tok-2".to_string()]);
+
+        // Taking clears the user's entry.
+        assert_eq!(reg.token_count("user-a"), 0);
+        assert_eq!(reg.user_count(), 0);
+        assert!(reg.take_for_user("user-a").is_empty());
+    }
+
+    #[test]
+    fn take_for_unknown_user_is_empty() {
+        let reg = ViewerTokenRegistry::new();
+        assert!(reg.take_for_user("nobody").is_empty());
+    }
+
+    #[test]
+    fn tokens_are_scoped_per_user() {
+        let reg = ViewerTokenRegistry::new();
+        reg.register("user-a", "a-tok", Duration::from_secs(300));
+        reg.register("user-b", "b-tok", Duration::from_secs(300));
+
+        assert_eq!(reg.take_for_user("user-a"), vec!["a-tok".to_string()]);
+        // user-b is untouched.
+        assert_eq!(reg.take_for_user("user-b"), vec!["b-tok".to_string()]);
+    }
+
+    #[test]
+    fn expired_tokens_are_not_returned_by_take() {
+        let reg = ViewerTokenRegistry::new();
+        // Zero TTL -> already expired by the time take runs.
+        reg.register("user-a", "expired", Duration::from_secs(0));
+        reg.register("user-a", "live", Duration::from_secs(300));
+
+        let taken = reg.take_for_user("user-a");
+        assert_eq!(taken, vec!["live".to_string()]);
+    }
+
+    #[test]
+    fn expired_tokens_are_pruned_on_insert() {
+        let reg = ViewerTokenRegistry::new();
+        // Register an already-expired token, then a live one for the same user.
+        reg.register("user-a", "expired", Duration::from_secs(0));
+        // First insert leaves 1 entry; the second insert prunes the expired one
+        // before pushing, so only the live token remains.
+        reg.register("user-a", "live", Duration::from_secs(300));
+
+        assert_eq!(reg.token_count("user-a"), 1);
+        assert_eq!(reg.take_for_user("user-a"), vec!["live".to_string()]);
+    }
+
+    #[test]
+    fn multiple_logins_accumulate_then_all_taken() {
+        // A user with several concurrent logins mints several viewer tokens;
+        // logout must revoke ALL of them at once.
+        let reg = ViewerTokenRegistry::new();
+        for i in 0..5 {
+            reg.register("user-a", &format!("tok-{i}"), Duration::from_secs(300));
+        }
+        assert_eq!(reg.token_count("user-a"), 5);
+        assert_eq!(reg.take_for_user("user-a").len(), 5);
+        assert_eq!(reg.user_count(), 0);
+    }
+}

server/src/main.rs

@@ -37,7 +37,10 @@ use tower_http::trace::TraceLayer;
 use tracing::{info, Level};
 use tracing_subscriber::FmtSubscriber;
 
-use auth::{generate_random_password, hash_password, AuthenticatedUser, JwtConfig, TokenBlacklist};
+use auth::{
+    generate_random_password, hash_password, AuthenticatedUser, JwtConfig, TokenBlacklist,
+    ViewerTokenRegistry,
+};
 
 /// Root of the static asset tree, relative to the server's working directory.
 /// Holds the agent `downloads/` tree AND the v2 SPA build under `app/`.
@@ -66,6 +69,13 @@ pub struct AppState {
     db: Option<db::Database>,
     pub jwt_config: Arc<JwtConfig>,
     pub token_blacklist: TokenBlacklist,
+    /// Per-user registry of outstanding session-scoped viewer tokens. Minting a
+    /// viewer token registers it here under the minting user's `sub`; logout
+    /// drains the user's registered viewer tokens into `token_blacklist` so a
+    /// just-logged-out user cannot keep a live viewer/remote-control plane until
+    /// the token's natural 5-minute expiry. The viewer WS already blacklist-
+    /// checks the exact token string, so no WS change is needed.
+    pub viewer_tokens: ViewerTokenRegistry,
     /// Optional API key for persistent agents (env: AGENT_API_KEY)
     pub agent_api_key: Option<String>,
     /// Prometheus metrics
@@ -291,6 +301,7 @@ async fn main() -> Result<()> {
 
     // Create application state
     let token_blacklist = TokenBlacklist::new();
+    let viewer_tokens = ViewerTokenRegistry::new();
 
     let state = AppState {
         sessions,
@@ -298,6 +309,7 @@ async fn main() -> Result<()> {
         db: database,
         jwt_config,
         token_blacklist,
+        viewer_tokens,
         agent_api_key,
         metrics,
         registry,

server/src/relay/mod.rs

@@ -772,8 +772,11 @@ async fn handle_agent_connection(
                                 let _ = frame_tx.send(data.to_vec());
                             }
                             Some(proto::message::Payload::ChatMessage(chat)) => {
-                                // Broadcast chat message to all viewers
-                                info!("Chat from client: {}", chat.content);
+                                // Broadcast chat message to all viewers. Do NOT log
+                                // the chat body: support-session chat can carry
+                                // secrets/PII. Log only the (non-sensitive) length
+                                // so relay activity stays observable.
+                                info!("Chat from client ({} chars)", chat.content.len());
                                 let _ = frame_tx.send(data.to_vec());
                             }
                             Some(proto::message::Payload::AgentStatus(status)) => {
@@ -1369,8 +1372,10 @@ async fn handle_viewer_connection(
                             }
                             Some(proto::message::Payload::ChatMessage(chat)) => {
                                 // Forward chat message to agent (not throttled —
-                                // not an injected-input vector). Bounded send.
-                                info!("Chat from technician: {}", chat.content);
+                                // not an injected-input vector). Bounded send. Do
+                                // NOT log the chat body (secrets/PII); log only the
+                                // (non-sensitive) length so the relay is observable.
+                                info!("Chat from technician ({} chars)", chat.content.len());
                                 let _ = input_tx.try_send(data.to_vec());
                             }
                             _ => {}