fix(security): address review feedback on cross-channel approval checks

1. thread_ops.rs: Remove .or(Some(&*message.channel)) fallback in
   maybe_hydrate_thread() so that when source_channel is NULL in the DB,
   it stays None rather than being stamped with the requesting channel.
   This preserves the fail-closed behavior of is_approval_authorized().

2. libsql_migrations.rs: Remove source_channel from base SCHEMA to
   eliminate duplicate column definition. The column is now added solely
   by V14 migration, preventing fresh databases from failing on startup.

3. wasm/setup.rs: Expand RESERVED_CHANNEL_NAMES to cover all built-in
   channels (http, signal, slack-relay, secret_save) and add a dynamic
   collision check against already-registered channel names passed from
   the startup sequence.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

migrations/V14__conversation_source_channel.sql

@@ -0,0 +1,4 @@
+-- Add source_channel to conversations for cross-channel approval authorization.
+-- Tracks which channel originally created a conversation so that approval
+-- messages from other channels can be validated.
+ALTER TABLE conversations ADD COLUMN source_channel TEXT;

src/agent/agent_loop.rs

@@ -843,7 +843,10 @@ impl Agent {
             {
                 use crate::agent::session::Thread;
                 let mut sess = session.lock().await;
-                let thread = Thread::with_id(id, sess.id);
+                // Bootstrap thread has no incoming message -- use the
+                // "__bootstrap__" sentinel so approvals from any channel are
+                // permitted. None means "deny by default" (fail-closed).
+                let thread = Thread::with_id(id, sess.id, Some("__bootstrap__"));
                 sess.active_thread = Some(id);
                 sess.threads.entry(id).or_insert(thread);
             }
@@ -1148,7 +1151,37 @@ impl Agent {
                 .get_or_create_session(&message.user_id)
                 .await;
             let mut sess = session.lock().await;
-            if sess.threads.contains_key(&target_thread_id) {
+            if let Some(thread) = sess.threads.get(&target_thread_id) {
+                // Verify the thread actually has a pending approval before
+                // allowing approval-shaped messages to target it. Without this
+                // check, an attacker could use approval messages to hijack any
+                // thread by UUID.
+                if thread.pending_approval.is_none() {
+                    tracing::warn!(
+                        %target_thread_id,
+                        approval_channel = %message.channel,
+                        "Blocked approval for thread with no pending approval"
+                    );
+                    drop(sess);
+                    return Ok(Some("Error: no pending approval on this thread".into()));
+                }
+
+                let authorized = crate::agent::session::is_approval_authorized(
+                    thread.source_channel.as_deref(),
+                    &message.channel,
+                );
+                if !authorized {
+                    tracing::warn!(
+                        %target_thread_id,
+                        source_channel = ?thread.source_channel,
+                        approval_channel = %message.channel,
+                        "Blocked cross-channel approval attempt"
+                    );
+                    drop(sess);
+                    return Ok(Some(
+                        "Error: approval not authorized for this channel".into(),
+                    ));
+                }
                 sess.active_thread = Some(target_thread_id);
                 sess.last_active_at = chrono::Utc::now();
                 drop(sess);

src/agent/compaction.rs

@@ -319,7 +319,7 @@ mod tests {
 
     #[test]
     fn test_format_turns() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         thread.start_turn("Hello");
         thread.complete_turn("Hi there");
         thread.start_turn("How are you?");
@@ -351,7 +351,7 @@ mod tests {
     /// Helper: build a thread with `n` completed turns.
     /// Turn `i` has user_input "msg-{i}" and response "resp-{i}".
     fn make_thread(n: usize) -> Thread {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         for i in 0..n {
             thread.start_turn(format!("msg-{}", i));
             thread.complete_turn(format!("resp-{}", i));
@@ -457,7 +457,7 @@ mod tests {
     async fn test_compact_truncate_empty_turns() {
         let llm = Arc::new(StubLlm::new("unused"));
         let compactor = make_compactor(llm);
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         assert!(thread.turns.is_empty());
 
         let result = compactor
@@ -698,7 +698,7 @@ mod tests {
 
     #[test]
     fn test_format_turns_for_storage_with_tool_calls() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         thread.start_turn("Search for X");
         // Record a tool call on the current turn
         if let Some(turn) = thread.turns.last_mut() {
@@ -719,7 +719,7 @@ mod tests {
 
     #[test]
     fn test_format_turns_for_storage_incomplete_turn() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         thread.start_turn("In progress message");
         // Don't complete the turn
 

src/agent/dispatcher.rs

@@ -2299,7 +2299,7 @@ mod tests {
         // Initialize a thread in the session so the loop can record tool calls.
         let thread_id = {
             let mut sess = session.lock().await;
-            sess.create_thread().id
+            sess.create_thread(Some("test")).id
         };
 
         let message = IncomingMessage::new("test", "test-user", "do something");
@@ -2412,7 +2412,7 @@ mod tests {
         let session = Arc::new(Mutex::new(Session::new("test-user")));
         let thread_id = {
             let mut sess = session.lock().await;
-            sess.create_thread().id
+            sess.create_thread(Some("test")).id
         };
 
         let message = IncomingMessage::new("test", "test-user", "keep calling tools");

src/agent/session.rs

@@ -68,8 +68,8 @@ impl Session {
     }
 
     /// Create a new thread in this session.
-    pub fn create_thread(&mut self) -> &mut Thread {
-        let thread = Thread::new(self.id);
+    pub fn create_thread(&mut self, channel: Option<&str>) -> &mut Thread {
+        let thread = Thread::new(self.id, channel);
         let thread_id = thread.id;
         self.active_thread = Some(thread_id);
         self.last_active_at = Utc::now();
@@ -87,9 +87,9 @@ impl Session {
     }
 
     /// Get or create the active thread.
-    pub fn get_or_create_thread(&mut self) -> &mut Thread {
+    pub fn get_or_create_thread(&mut self, channel: Option<&str>) -> &mut Thread {
         match self.active_thread {
-            None => self.create_thread(),
+            None => self.create_thread(channel),
             Some(id) => {
                 if self.threads.contains_key(&id) {
                     // Entry existence confirmed by contains_key above.
@@ -100,7 +100,7 @@ impl Session {
                 } else {
                     // Stale active_thread ID: create a new thread, which
                     // updates self.active_thread to the new thread's ID.
-                    self.create_thread()
+                    self.create_thread(channel)
                 }
             }
         }
@@ -225,6 +225,9 @@ pub struct Thread {
     /// Messages queued while the thread was processing a turn.
     #[serde(default, skip_serializing_if = "VecDeque::is_empty")]
     pub pending_messages: VecDeque<String>,
+    /// Channel that created this thread (for approval authorization).
+    #[serde(default)]
+    pub source_channel: Option<String>,
 }
 
 /// Maximum number of messages that can be queued while a thread is processing.
@@ -233,9 +236,29 @@ pub struct Thread {
 /// rapid follow-ups. The drain loop processes them as one newline-delimited turn.
 pub const MAX_PENDING_MESSAGES: usize = 10;
 
+/// Sentinel value for bootstrap threads that accept approvals from any channel.
+pub const BOOTSTRAP_SOURCE_CHANNEL: &str = "__bootstrap__";
+
+/// Check whether an approval from `requesting_channel` is authorized for a
+/// thread whose `source_channel` is `source`.
+///
+/// Rules:
+/// - `None` (unknown origin) -> denied (fail-closed)
+/// - `Some("__bootstrap__")` -> authorized from any channel
+/// - `Some(src) == requesting` -> same channel, authorized
+/// - requesting is "web" or "gateway" -> always authorized (trusted UI)
+/// - Otherwise -> denied
+pub fn is_approval_authorized(source: Option<&str>, requesting: &str) -> bool {
+    match source {
+        None => false,
+        Some(src) if src == BOOTSTRAP_SOURCE_CHANNEL => true,
+        Some(src) => src == requesting || requesting == "web" || requesting == "gateway",
+    }
+}
+
 impl Thread {
     /// Create a new thread.
-    pub fn new(session_id: Uuid) -> Self {
+    pub fn new(session_id: Uuid, source_channel: Option<&str>) -> Self {
         let now = Utc::now();
         Self {
             id: Uuid::new_v4(),
@@ -248,11 +271,12 @@ impl Thread {
             pending_approval: None,
             pending_auth: None,
             pending_messages: VecDeque::new(),
+            source_channel: source_channel.map(String::from),
         }
     }
 
     /// Create a thread with a specific ID (for DB hydration).
-    pub fn with_id(id: Uuid, session_id: Uuid) -> Self {
+    pub fn with_id(id: Uuid, session_id: Uuid, source_channel: Option<&str>) -> Self {
         let now = Utc::now();
         Self {
             id,
@@ -265,6 +289,7 @@ impl Thread {
             pending_approval: None,
             pending_auth: None,
             pending_messages: VecDeque::new(),
+            source_channel: source_channel.map(String::from),
         }
     }
 
@@ -787,13 +812,13 @@ mod tests {
         let mut session = Session::new("user-123");
         assert!(session.active_thread.is_none());
 
-        session.create_thread();
+        session.create_thread(None);
         assert!(session.active_thread.is_some());
     }
 
     #[test]
     fn test_thread_turns() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("Hello");
         assert_eq!(thread.state, ThreadState::Processing);
@@ -806,7 +831,7 @@ mod tests {
 
     #[test]
     fn test_thread_messages() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("First message");
         thread.complete_turn("First response");
@@ -829,7 +854,7 @@ mod tests {
 
     #[test]
     fn test_restore_from_messages() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // First add some turns
         thread.start_turn("Original message");
@@ -855,7 +880,7 @@ mod tests {
 
     #[test]
     fn test_restore_from_messages_incomplete_turn() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Messages with incomplete last turn (no assistant response)
         let messages = vec![
@@ -874,7 +899,7 @@ mod tests {
     #[test]
     fn test_enter_auth_mode() {
         let before = Utc::now();
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         assert!(thread.pending_auth.is_none());
 
         thread.enter_auth_mode("telegram".to_string());
@@ -887,7 +912,7 @@ mod tests {
 
     #[test]
     fn test_take_pending_auth() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         thread.enter_auth_mode("notion".to_string());
 
         let pending = thread.take_pending_auth();
@@ -902,7 +927,7 @@ mod tests {
 
     #[test]
     fn test_pending_auth_serialization() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         thread.enter_auth_mode("openai".to_string());
 
         let json = serde_json::to_string(&thread).expect("should serialize");
@@ -932,7 +957,7 @@ mod tests {
     #[test]
     fn test_pending_auth_default_none() {
         // Deserialization of old data without pending_auth should default to None
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         thread.pending_auth = None;
         let json = serde_json::to_string(&thread).expect("serialize");
 
@@ -946,7 +971,7 @@ mod tests {
     fn test_thread_with_id() {
         let specific_id = Uuid::new_v4();
         let session_id = Uuid::new_v4();
-        let thread = Thread::with_id(specific_id, session_id);
+        let thread = Thread::with_id(specific_id, session_id, None);
 
         assert_eq!(thread.id, specific_id);
         assert_eq!(thread.session_id, session_id);
@@ -958,7 +983,7 @@ mod tests {
     fn test_thread_with_id_restore_messages() {
         let thread_id = Uuid::new_v4();
         let session_id = Uuid::new_v4();
-        let mut thread = Thread::with_id(thread_id, session_id);
+        let mut thread = Thread::with_id(thread_id, session_id, None);
 
         let messages = vec![
             ChatMessage::user("Hello from DB"),
@@ -977,7 +1002,7 @@ mod tests {
 
     #[test]
     fn test_restore_from_messages_empty() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Add a turn first, then restore with empty vec
         thread.start_turn("hello");
@@ -993,7 +1018,7 @@ mod tests {
 
     #[test]
     fn test_restore_from_messages_only_assistant_messages() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Only assistant messages (no user messages to anchor turns)
         let messages = vec![
@@ -1010,7 +1035,7 @@ mod tests {
 
     #[test]
     fn test_restore_from_messages_multiple_user_messages_in_a_row() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Two user messages with no assistant response between them
         let messages = vec![
@@ -1037,8 +1062,8 @@ mod tests {
     fn test_thread_switch() {
         let mut session = Session::new("user-1");
 
-        let t1_id = session.create_thread().id;
-        let t2_id = session.create_thread().id;
+        let t1_id = session.create_thread(None).id;
+        let t2_id = session.create_thread(None).id;
 
         // After creating two threads, active should be the last one
         assert_eq!(session.active_thread, Some(t2_id));
@@ -1058,8 +1083,8 @@ mod tests {
     fn test_get_or_create_thread_idempotent() {
         let mut session = Session::new("user-1");
 
-        let tid1 = session.get_or_create_thread().id;
-        let tid2 = session.get_or_create_thread().id;
+        let tid1 = session.get_or_create_thread(None).id;
+        let tid2 = session.get_or_create_thread(None).id;
 
         // Should return the same thread (not create a new one each time)
         assert_eq!(tid1, tid2);
@@ -1068,7 +1093,7 @@ mod tests {
 
     #[test]
     fn test_truncate_turns() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         for i in 0..5 {
             thread.start_turn(format!("msg-{}", i));
@@ -1092,7 +1117,7 @@ mod tests {
 
     #[test]
     fn test_truncate_turns_noop_when_fewer() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("only one");
         thread.complete_turn("response");
@@ -1104,7 +1129,7 @@ mod tests {
 
     #[test]
     fn test_thread_interrupt_and_resume() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("do something");
         assert_eq!(thread.state, ThreadState::Processing);
@@ -1122,7 +1147,7 @@ mod tests {
 
     #[test]
     fn test_resume_only_from_interrupted() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Idle thread: resume should be a no-op
         assert_eq!(thread.state, ThreadState::Idle);
@@ -1138,7 +1163,7 @@ mod tests {
 
     #[test]
     fn test_turn_fail() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("risky operation");
         thread.fail_turn("connection timed out");
@@ -1154,7 +1179,7 @@ mod tests {
 
     #[test]
     fn test_messages_with_incomplete_last_turn() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("first");
         thread.complete_turn("first reply");
@@ -1170,7 +1195,7 @@ mod tests {
 
     #[test]
     fn test_thread_serialization_round_trip() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("hello");
         thread.complete_turn("world");
@@ -1188,7 +1213,7 @@ mod tests {
     #[test]
     fn test_session_serialization_round_trip() {
         let mut session = Session::new("user-ser");
-        session.create_thread();
+        session.create_thread(None);
         session.auto_approve_tool("echo");
 
         let json = serde_json::to_string(&session).unwrap();
@@ -1226,7 +1251,7 @@ mod tests {
 
     #[test]
     fn test_turn_number_increments() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Before any turns, turn_number() is 1 (1-indexed for display)
         assert_eq!(thread.turn_number(), 1);
@@ -1241,7 +1266,7 @@ mod tests {
 
     #[test]
     fn test_complete_turn_on_empty_thread() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Completing a turn when there are no turns should be a safe no-op
         thread.complete_turn("phantom response");
@@ -1251,7 +1276,7 @@ mod tests {
 
     #[test]
     fn test_fail_turn_on_empty_thread() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Failing a turn when there are no turns should be a safe no-op
         thread.fail_turn("phantom error");
@@ -1261,7 +1286,7 @@ mod tests {
 
     #[test]
     fn test_pending_approval_flow() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         let approval = PendingApproval {
             request_id: Uuid::new_v4(),
@@ -1288,7 +1313,7 @@ mod tests {
 
     #[test]
     fn test_clear_pending_approval() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         let approval = PendingApproval {
             request_id: Uuid::new_v4(),
@@ -1317,7 +1342,7 @@ mod tests {
         assert!(session.active_thread().is_none());
         assert!(session.active_thread_mut().is_none());
 
-        let tid = session.create_thread().id;
+        let tid = session.create_thread(None).id;
 
         assert!(session.active_thread().is_some());
         assert_eq!(session.active_thread().unwrap().id, tid);
@@ -1334,7 +1359,7 @@ mod tests {
 
     #[test]
     fn test_messages_includes_tool_calls() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("Search for X");
         {
@@ -1366,7 +1391,7 @@ mod tests {
 
     #[test]
     fn test_messages_multiple_tool_calls_per_turn() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("Do two things");
         {
@@ -1393,7 +1418,7 @@ mod tests {
 
     #[test]
     fn test_restore_from_messages_with_tool_calls() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Build a message sequence with tool calls
         let tc = ToolCall {
@@ -1425,7 +1450,7 @@ mod tests {
 
     #[test]
     fn test_restore_from_messages_with_tool_error() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         let tc = ToolCall {
             id: "call_0".to_string(),
@@ -1456,7 +1481,7 @@ mod tests {
     fn test_messages_round_trip_with_tools() {
         // Build a thread with tool calls, get messages(), restore, get messages() again
         // The two message sequences should be equivalent.
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("Do search");
         {
@@ -1469,7 +1494,7 @@ mod tests {
         let messages_original = thread.messages();
 
         // Restore into a new thread
-        let mut thread2 = Thread::new(Uuid::new_v4());
+        let mut thread2 = Thread::new(Uuid::new_v4(), None);
         thread2.restore_from_messages(messages_original.clone());
 
         let messages_restored = thread2.messages();
@@ -1491,7 +1516,7 @@ mod tests {
 
     #[test]
     fn test_restore_multi_stage_tool_calls() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         let tc1 = ToolCall {
             id: "call_a".to_string(),
@@ -1534,7 +1559,7 @@ mod tests {
 
     #[test]
     fn test_messages_truncates_large_tool_results() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         thread.start_turn("Read big file");
         {
@@ -1557,7 +1582,7 @@ mod tests {
 
     #[test]
     fn test_thread_message_queue() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Queue is initially empty
         assert!(thread.pending_messages.is_empty());
@@ -1593,7 +1618,7 @@ mod tests {
 
     #[test]
     fn test_thread_message_queue_serialization() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Empty queue should not appear in serialization (skip_serializing_if)
         let json = serde_json::to_string(&thread).unwrap();
@@ -1613,7 +1638,7 @@ mod tests {
     #[test]
     fn test_thread_message_queue_default_on_old_data() {
         // Deserialization of old data without pending_messages should default to empty
-        let thread = Thread::new(Uuid::new_v4());
+        let thread = Thread::new(Uuid::new_v4(), None);
         let json = serde_json::to_string(&thread).unwrap();
 
         // The field is absent (skip_serializing_if), simulating old data
@@ -1624,7 +1649,7 @@ mod tests {
 
     #[test]
     fn test_interrupt_clears_pending_messages() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Start a turn so there's something to interrupt
         thread.start_turn("initial input");
@@ -1643,7 +1668,7 @@ mod tests {
 
     #[test]
     fn test_thread_state_idle_after_full_drain() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Simulate a full drain cycle: start turn, queue messages, complete turn,
         // then drain all queued messages as a single merged turn (#259).
@@ -1671,7 +1696,7 @@ mod tests {
 
     #[test]
     fn test_drain_pending_messages_merges_with_newlines() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Empty queue returns None
         assert!(thread.drain_pending_messages().is_none());
@@ -1700,7 +1725,7 @@ mod tests {
 
     #[test]
     fn test_requeue_drained_preserves_content_at_front() {
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
 
         // Re-queue into empty queue
         thread.requeue_drained("failed batch".to_string());
@@ -1811,4 +1836,94 @@ mod tests {
             &serde_json::json!("done")
         );
     }
+
+    #[test]
+    fn test_thread_new_stores_source_channel() {
+        let thread = Thread::new(Uuid::new_v4(), Some("telegram"));
+        assert_eq!(thread.source_channel.as_deref(), Some("telegram"));
+    }
+
+    #[test]
+    fn test_thread_new_none_channel() {
+        let thread = Thread::new(Uuid::new_v4(), None);
+        assert!(thread.source_channel.is_none());
+    }
+
+    #[test]
+    fn test_source_channel_serde_backcompat() {
+        // Simulate deserializing a Thread from older DB records that lack source_channel.
+        let thread = Thread::new(Uuid::new_v4(), Some("cli"));
+        let json = serde_json::to_string(&thread).unwrap();
+
+        // Remove the source_channel field to simulate an old record.
+        let mut value: serde_json::Value = serde_json::from_str(&json).unwrap();
+        value.as_object_mut().unwrap().remove("source_channel");
+        let old_json = serde_json::to_string(&value).unwrap();
+
+        let deserialized: Thread = serde_json::from_str(&old_json).unwrap();
+        assert!(
+            deserialized.source_channel.is_none(),
+            "missing source_channel should deserialize as None"
+        );
+    }
+
+    #[test]
+    fn test_approval_authorized_same_channel() {
+        assert!(
+            is_approval_authorized(Some("telegram"), "telegram"),
+            "same channel should be authorized"
+        );
+    }
+
+    #[test]
+    fn test_approval_authorized_different_channel_blocked() {
+        assert!(
+            !is_approval_authorized(Some("telegram"), "http"),
+            "different channel should be blocked"
+        );
+    }
+
+    #[test]
+    fn test_approval_authorized_web_always_allowed() {
+        assert!(
+            is_approval_authorized(Some("telegram"), "web"),
+            "web channel should always be authorized"
+        );
+    }
+
+    #[test]
+    fn test_approval_authorized_gateway_always_allowed() {
+        assert!(
+            is_approval_authorized(Some("telegram"), "gateway"),
+            "gateway channel should always be authorized"
+        );
+    }
+
+    #[test]
+    fn test_approval_authorized_none_denied() {
+        assert!(
+            !is_approval_authorized(None, "telegram"),
+            "None source_channel should be denied (fail-closed)"
+        );
+        assert!(
+            !is_approval_authorized(None, "web"),
+            "None source_channel should be denied even for web"
+        );
+    }
+
+    #[test]
+    fn test_approval_authorized_bootstrap_any_channel() {
+        assert!(
+            is_approval_authorized(Some(BOOTSTRAP_SOURCE_CHANNEL), "telegram"),
+            "__bootstrap__ should be authorized from any channel"
+        );
+        assert!(
+            is_approval_authorized(Some(BOOTSTRAP_SOURCE_CHANNEL), "http"),
+            "__bootstrap__ should be authorized from any channel"
+        );
+        assert!(
+            is_approval_authorized(Some(BOOTSTRAP_SOURCE_CHANNEL), "cli"),
+            "__bootstrap__ should be authorized from any channel"
+        );
+    }
 }

src/agent/session_manager.rs

@@ -200,7 +200,7 @@ impl SessionManager {
         // Create new thread (always create a new one for a new key)
         let thread_id = {
             let mut sess = session.lock().await;
-            let thread = sess.create_thread();
+            let thread = sess.create_thread(Some(channel));
             thread.id
         };
 
@@ -476,7 +476,7 @@ mod tests {
         let session = Arc::new(Mutex::new(Session::new("user-hydrate")));
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(thread_id, sess.id);
+            let thread = Thread::with_id(thread_id, sess.id, None);
             sess.threads.insert(thread_id, thread);
             sess.active_thread = Some(thread_id);
         }
@@ -600,7 +600,7 @@ mod tests {
         // Simulate hydration: create thread with a known UUID
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(known_uuid, session_id);
+            let thread = Thread::with_id(known_uuid, session_id, None);
             sess.threads.insert(known_uuid, thread);
         }
 
@@ -627,7 +627,7 @@ mod tests {
         let session = Arc::new(Mutex::new(Session::new("user-idem")));
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(tid, sess.id);
+            let thread = Thread::with_id(tid, sess.id, None);
             sess.threads.insert(tid, thread);
         }
 
@@ -656,7 +656,7 @@ mod tests {
         let session = Arc::new(Mutex::new(Session::new("user-undo")));
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(tid, sess.id);
+            let thread = Thread::with_id(tid, sess.id, None);
             sess.threads.insert(tid, thread);
         }
 
@@ -680,7 +680,7 @@ mod tests {
         let session = Arc::new(Mutex::new(Session::new("user-new")));
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(tid, sess.id);
+            let thread = Thread::with_id(tid, sess.id, None);
             sess.threads.insert(tid, thread);
         }
 
@@ -788,7 +788,7 @@ mod tests {
         let session = Arc::new(Mutex::new(Session::new("user-cross")));
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(tid, sess.id);
+            let thread = Thread::with_id(tid, sess.id, None);
             sess.threads.insert(tid, thread);
         }
 
@@ -815,7 +815,7 @@ mod tests {
         let session = Arc::new(Mutex::new(Session::new("user-cross")));
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(tid, sess.id);
+            let thread = Thread::with_id(tid, sess.id, None);
             sess.threads.insert(tid, thread);
         }
 
@@ -966,7 +966,7 @@ mod tests {
         let adopted_id = Uuid::new_v4();
         {
             let mut sess = session1.lock().await;
-            let thread = Thread::with_id(adopted_id, sess.id);
+            let thread = Thread::with_id(adopted_id, sess.id, None);
             sess.threads.insert(adopted_id, thread);
         }
         // Resolve with the UUID as external_thread_id -- should adopt it
@@ -992,7 +992,7 @@ mod tests {
         let session = Arc::new(Mutex::new(Session::new("user-direct")));
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(tid, sess.id);
+            let thread = Thread::with_id(tid, sess.id, None);
             sess.threads.insert(tid, thread);
         }
         {
@@ -1030,7 +1030,7 @@ mod tests {
         let known_id = Uuid::new_v4();
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(known_id, sess.id);
+            let thread = Thread::with_id(known_id, sess.id, None);
             sess.threads.insert(known_id, thread);
         }
 
@@ -1057,7 +1057,7 @@ mod tests {
         let known_id = Uuid::new_v4();
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(known_id, sess.id);
+            let thread = Thread::with_id(known_id, sess.id, None);
             sess.threads.insert(known_id, thread);
         }
 
@@ -1081,7 +1081,7 @@ mod tests {
         let known_id = Uuid::new_v4();
         {
             let mut sess = session.lock().await;
-            let thread = Thread::with_id(known_id, sess.id);
+            let thread = Thread::with_id(known_id, sess.id, None);
             sess.threads.insert(known_id, thread);
         }
 
@@ -1102,4 +1102,19 @@ mod tests {
             "should NOT adopt UUID when external_thread_id is None"
         );
     }
+
+    #[tokio::test]
+    async fn test_thread_stores_source_channel() {
+        let manager = SessionManager::new();
+
+        let (session, thread_id) = manager.resolve_thread("user-1", "telegram", None).await;
+
+        let sess = session.lock().await;
+        let thread = sess.threads.get(&thread_id).unwrap();
+        assert_eq!(
+            thread.source_channel.as_deref(),
+            Some("telegram"),
+            "resolve_thread should store source_channel from the channel parameter"
+        );
+    }
 }

src/agent/thread_ops.rs

@@ -135,13 +135,29 @@ impl Agent {
             msg_count = 0;
         }
 
-        // Create thread with the historical ID and restore messages
+        // Create thread with the historical ID and restore messages.
+        // Read source_channel from DB so the authorization check uses the
+        // original creator's channel, not the requesting message's channel.
+        let db_source_channel = if let Some(store) = self.store() {
+            store
+                .get_conversation_source_channel(thread_uuid)
+                .await
+                .unwrap_or(None)
+        } else {
+            None
+        };
+        let effective_source_channel = db_source_channel.as_deref();
+
         let session_id = {
             let sess = session.lock().await;
             sess.id
         };
 
-        let mut thread = crate::agent::session::Thread::with_id(thread_uuid, session_id);
+        let mut thread = crate::agent::session::Thread::with_id(
+            thread_uuid,
+            session_id,
+            effective_source_channel,
+        );
         if !chat_messages.is_empty() {
             thread.restore_from_messages(chat_messages);
         }
@@ -636,7 +652,7 @@ impl Agent {
         user_id: &str,
     ) -> bool {
         match store
-            .ensure_conversation(thread_id, channel, user_id, None)
+            .ensure_conversation(thread_id, channel, user_id, None, Some(channel))
             .await
         {
             Ok(true) => true,
@@ -1781,7 +1797,7 @@ impl Agent {
             .get_or_create_session(&message.user_id)
             .await;
         let mut sess = session.lock().await;
-        let thread = sess.create_thread();
+        let thread = sess.create_thread(Some(&message.channel));
         let thread_id = thread.id;
         Ok(SubmissionResult::ok_with_message(format!(
             "New thread: {}",
@@ -2117,7 +2133,7 @@ mod tests {
 
         let session_id = Uuid::new_v4();
         let thread_id = Uuid::new_v4();
-        let mut thread = Thread::with_id(thread_id, session_id);
+        let mut thread = Thread::with_id(thread_id, session_id, None);
 
         // Set thread to AwaitingApproval with a pending tool approval
         let pending = PendingApproval {
@@ -2185,7 +2201,7 @@ mod tests {
         use crate::agent::session::{MAX_PENDING_MESSAGES, Thread, ThreadState};
         use uuid::Uuid;
 
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         thread.start_turn("processing something");
         assert_eq!(thread.state, ThreadState::Processing);
 
@@ -2211,7 +2227,7 @@ mod tests {
         use crate::agent::session::{Thread, ThreadState};
         use uuid::Uuid;
 
-        let mut thread = Thread::new(Uuid::new_v4());
+        let mut thread = Thread::new(Uuid::new_v4(), None);
         thread.start_turn("processing");
 
         thread.queue_message("pending-1".to_string());
@@ -2241,7 +2257,7 @@ mod tests {
 
         let thread_id = Uuid::new_v4();
         let session_id = Uuid::new_v4();
-        let mut thread = Thread::with_id(thread_id, session_id);
+        let mut thread = Thread::with_id(thread_id, session_id, None);
         thread.start_turn("working");
         assert_eq!(thread.state, ThreadState::Processing);
 
@@ -2268,7 +2284,7 @@ mod tests {
 
         let thread_id = Uuid::new_v4();
         let session_id = Uuid::new_v4();
-        let mut thread = Thread::with_id(thread_id, session_id);
+        let mut thread = Thread::with_id(thread_id, session_id, None);
         thread.start_turn("working");
         assert_eq!(thread.state, ThreadState::Processing);
 

src/channels/wasm/setup.rs

@@ -34,6 +34,7 @@ pub async fn setup_wasm_channels(
     secrets_store: &Option<Arc<dyn SecretsStore + Send + Sync>>,
     extension_manager: Option<&Arc<ExtensionManager>>,
     database: Option<&Arc<dyn Database>>,
+    registered_channel_names: &[String],
 ) -> Option<WasmChannelSetup> {
     let runtime = match WasmChannelRuntime::new(WasmChannelRuntimeConfig::default()) {
         Ok(r) => Arc::new(r),
@@ -71,7 +72,46 @@ pub async fn setup_wasm_channels(
     let mut channels: Vec<(String, Box<dyn crate::channels::Channel>)> = Vec::new();
     let mut channel_names: Vec<String> = Vec::new();
 
+    // Reserved channel names that WASM modules must not claim.
+    // A malicious module could otherwise register as a trusted built-in
+    // channel and bypass cross-channel authorization checks.
+    // This list must cover every built-in channel name to prevent a WASM
+    // module from impersonating a built-in and satisfying same-channel
+    // approval checks.
+    const RESERVED_CHANNEL_NAMES: &[&str] = &[
+        "web",
+        "gateway",
+        "cli",
+        "repl",
+        "http",
+        "signal",
+        "slack-relay",
+        "secret_save",
+    ];
+
     for loaded in results.loaded {
+        let name_lower = loaded.name().to_ascii_lowercase();
+        if RESERVED_CHANNEL_NAMES.contains(&name_lower.as_str()) {
+            tracing::warn!(
+                channel = %loaded.name(),
+                "Rejected WASM channel with reserved name"
+            );
+            continue;
+        }
+        // Also reject any name that collides with an already-registered
+        // channel to prevent a WASM module from shadowing a channel that
+        // was registered earlier in the startup sequence.
+        if registered_channel_names
+            .iter()
+            .any(|n| n.to_ascii_lowercase() == name_lower)
+        {
+            tracing::warn!(
+                channel = %loaded.name(),
+                "Rejected WASM channel that collides with already-registered channel"
+            );
+            continue;
+        }
+
         let (name, channel) = register_channel(
             loaded,
             config,

src/channels/web/handlers/chat.rs

@@ -574,7 +574,7 @@ pub async fn chat_new_thread_handler(
         .await;
     let (thread_id, info) = {
         let mut sess = session.lock().await;
-        let thread = sess.create_thread();
+        let thread = sess.create_thread(Some("web"));
         let id = thread.id;
         let info = ThreadInfo {
             id: thread.id,
@@ -593,7 +593,13 @@ pub async fn chat_new_thread_handler(
     // so that the subsequent loadThreads() call from the frontend sees it.
     if let Some(ref store) = state.store {
         match store
-            .ensure_conversation(thread_id, "gateway", &identity.user_id, None)
+            .ensure_conversation(
+                thread_id,
+                "gateway",
+                &identity.user_id,
+                None,
+                Some("gateway"),
+            )
             .await
         {
             Ok(true) => {}

src/channels/web/server.rs

@@ -2014,7 +2014,7 @@ async fn chat_new_thread_handler(
     let session = session_manager.get_or_create_session(&user.user_id).await;
     let (thread_id, info) = {
         let mut sess = session.lock().await;
-        let thread = sess.create_thread();
+        let thread = sess.create_thread(Some("gateway"));
         let id = thread.id;
         let info = ThreadInfo {
             id: thread.id,
@@ -2033,7 +2033,7 @@ async fn chat_new_thread_handler(
     // so that the subsequent loadThreads() call from the frontend sees it.
     if let Some(ref store) = state.store {
         match store
-            .ensure_conversation(thread_id, "gateway", &user.user_id, None)
+            .ensure_conversation(thread_id, "gateway", &user.user_id, None, Some("gateway"))
             .await
         {
             Ok(true) => {}

src/db/libsql/conversations.rs

@@ -67,19 +67,20 @@ impl ConversationStore for LibSqlBackend {
         channel: &str,
         user_id: &str,
         thread_id: Option<&str>,
+        source_channel: Option<&str>,
     ) -> Result<bool, DatabaseError> {
         let conn = self.connect().await?;
         let now = fmt_ts(&Utc::now());
         let affected = conn
             .execute(
             r#"
-                INSERT INTO conversations (id, channel, user_id, thread_id, started_at, last_activity)
-                VALUES (?1, ?2, ?3, ?4, ?5, ?5)
+                INSERT INTO conversations (id, channel, user_id, thread_id, source_channel, started_at, last_activity)
+                VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?6)
                 ON CONFLICT (id) DO UPDATE SET last_activity = excluded.last_activity
                 WHERE conversations.user_id = excluded.user_id
                   AND conversations.channel = excluded.channel
                 "#,
-            params![id.to_string(), channel, user_id, opt_text(thread_id), now],
+            params![id.to_string(), channel, user_id, opt_text(thread_id), opt_text(source_channel), now],
         )
             .await
             .map_err(|e| DatabaseError::Query(e.to_string()))?;
@@ -565,6 +566,28 @@ impl ConversationStore for LibSqlBackend {
             .map_err(|e| DatabaseError::Query(e.to_string()))?;
         Ok(found.is_some())
     }
+
+    async fn get_conversation_source_channel(
+        &self,
+        conversation_id: Uuid,
+    ) -> Result<Option<String>, DatabaseError> {
+        let conn = self.connect().await?;
+        let mut rows = conn
+            .query(
+                "SELECT source_channel FROM conversations WHERE id = ?1",
+                params![conversation_id.to_string()],
+            )
+            .await
+            .map_err(|e| DatabaseError::Query(e.to_string()))?;
+        match rows
+            .next()
+            .await
+            .map_err(|e| DatabaseError::Query(e.to_string()))?
+        {
+            Some(row) => Ok(get_opt_text(&row, 0)),
+            None => Ok(None),
+        }
+    }
 }
 
 #[cfg(test)]

src/db/libsql/users.rs

@@ -981,7 +981,7 @@ mod tests {
         assert!(alice_stats.last_active_at.is_some());
 
         // Bob has no LLM calls so doesn't appear in summary stats
-        assert!(stats.iter().find(|s| s.user_id == "bob").is_none());
+        assert!(!stats.iter().any(|s| s.user_id == "bob"));
 
         // Filter to single user
         let alice_only = db.user_summary_stats(Some("alice")).await.unwrap();

src/db/libsql_migrations.rs

@@ -785,6 +785,14 @@ CREATE TABLE IF NOT EXISTS api_tokens (
 );
 CREATE INDEX IF NOT EXISTS idx_api_tokens_user ON api_tokens(user_id);
 CREATE INDEX IF NOT EXISTS idx_api_tokens_hash ON api_tokens(token_hash);
+"#,
+    ),
+    (
+        15,
+        "conversation_source_channel",
+        // Add source_channel to conversations for cross-channel approval authorization.
+        r#"
+ALTER TABLE conversations ADD COLUMN source_channel TEXT;
 "#,
     ),
 ];

src/db/mod.rs

@@ -373,6 +373,7 @@ pub trait ConversationStore: Send + Sync {
         channel: &str,
         user_id: &str,
         thread_id: Option<&str>,
+        source_channel: Option<&str>,
     ) -> Result<bool, DatabaseError>;
     async fn list_conversations_with_preview(
         &self,
@@ -431,6 +432,11 @@ pub trait ConversationStore: Send + Sync {
         conversation_id: Uuid,
         user_id: &str,
     ) -> Result<bool, DatabaseError>;
+    /// Get the source_channel for a conversation (the channel that created it).
+    async fn get_conversation_source_channel(
+        &self,
+        conversation_id: Uuid,
+    ) -> Result<Option<String>, DatabaseError>;
 }
 
 #[async_trait]

src/db/postgres.rs

@@ -99,9 +99,10 @@ impl ConversationStore for PgBackend {
         channel: &str,
         user_id: &str,
         thread_id: Option<&str>,
+        source_channel: Option<&str>,
     ) -> Result<bool, DatabaseError> {
         self.store
-            .ensure_conversation(id, channel, user_id, thread_id)
+            .ensure_conversation(id, channel, user_id, thread_id, source_channel)
             .await
     }
 
@@ -212,6 +213,15 @@ impl ConversationStore for PgBackend {
             .conversation_belongs_to_user(conversation_id, user_id)
             .await
     }
+
+    async fn get_conversation_source_channel(
+        &self,
+        conversation_id: Uuid,
+    ) -> Result<Option<String>, DatabaseError> {
+        self.store
+            .get_conversation_source_channel(conversation_id)
+            .await
+    }
 }
 
 // ==================== JobStore ====================

src/history/store.rs

@@ -1581,19 +1581,20 @@ impl Store {
         channel: &str,
         user_id: &str,
         thread_id: Option<&str>,
+        source_channel: Option<&str>,
     ) -> Result<bool, DatabaseError> {
         let conn = self.conn().await?;
         let affected = conn
             .execute(
                 r#"
-            INSERT INTO conversations (id, channel, user_id, thread_id)
-            VALUES ($1, $2, $3, $4)
+            INSERT INTO conversations (id, channel, user_id, thread_id, source_channel)
+            VALUES ($1, $2, $3, $4, $5)
             ON CONFLICT (id) DO UPDATE
             SET last_activity = NOW()
             WHERE conversations.user_id = EXCLUDED.user_id
               AND conversations.channel = EXCLUDED.channel
             "#,
-                &[&id, &channel, &user_id, &thread_id],
+                &[&id, &channel, &user_id, &thread_id, &source_channel],
             )
             .await?;
         Ok(affected > 0)
@@ -1892,6 +1893,21 @@ impl Store {
         Ok(row.is_some())
     }
 
+    /// Get the source_channel for a conversation.
+    pub async fn get_conversation_source_channel(
+        &self,
+        conversation_id: Uuid,
+    ) -> Result<Option<String>, DatabaseError> {
+        let conn = self.conn().await?;
+        let row = conn
+            .query_opt(
+                "SELECT source_channel FROM conversations WHERE id = $1",
+                &[&conversation_id],
+            )
+            .await?;
+        Ok(row.and_then(|r| r.get::<_, Option<String>>(0)))
+    }
+
     /// Load messages for a conversation with cursor-based pagination.
     ///
     /// Returns `(messages_oldest_first, has_more)`.

src/main.rs

@@ -449,6 +449,7 @@ async fn async_main() -> anyhow::Result<()> {
             &components.secrets_store,
             components.extension_manager.as_ref(),
             components.db.as_ref(),
+            &channel_names,
         )
         .await;
 

src/tenant.rs

@@ -278,7 +278,7 @@ impl TenantScope {
         thread_id: Option<&str>,
     ) -> Result<bool, DatabaseError> {
         self.inner
-            .ensure_conversation(id, channel, &self.user_id, thread_id)
+            .ensure_conversation(id, channel, &self.user_id, thread_id, None)
             .await
     }
 

src/testing/mod.rs

@@ -753,7 +753,7 @@ mod tests {
 
         // ensure_conversation should create the row.
         assert!(
-            db.ensure_conversation(conv_id, "web", "carol", None)
+            db.ensure_conversation(conv_id, "web", "carol", None, Some("web"))
                 .await
                 .expect("ensure first"),
             "first ensure_conversation should create the row"
@@ -761,7 +761,7 @@ mod tests {
 
         // Calling again with the same ID should not error.
         assert!(
-            db.ensure_conversation(conv_id, "web", "carol", None)
+            db.ensure_conversation(conv_id, "web", "carol", None, Some("web"))
                 .await
                 .expect("ensure second (idempotent)"),
             "second ensure_conversation should touch owned row"
@@ -806,7 +806,7 @@ mod tests {
         tokio::time::sleep(std::time::Duration::from_millis(25)).await;
 
         assert!(
-            !db.ensure_conversation(conv_id, "web", "mallory", None)
+            !db.ensure_conversation(conv_id, "web", "mallory", None, None)
                 .await
                 .expect("foreign ensure should not error"),
             "foreign ensure_conversation should report not ensured"

tests/e2e_thread_id_isolation.rs

@@ -48,7 +48,13 @@ mod tests {
         let store = rig.database();
         assert!(
             store
-                .ensure_conversation(foreign_thread_id, "gateway", "victim-user", None)
+                .ensure_conversation(
+                    foreign_thread_id,
+                    "gateway",
+                    "victim-user",
+                    None,
+                    Some("gateway")
+                )
                 .await
                 .expect("failed to create victim conversation"),
             "test setup failed: victim conversation was not created"