chore: add attach-gate debug log and skip-list maintenance warning

src/components/TerminalView.tsx

@@ -2477,6 +2477,11 @@ function TerminalView({ tabId, paneId, paneContent, hidden }: TerminalViewProps)
     // close-during-create race and stale deferred re-attach timers.
     const layouts = appStore.getState().panes.layouts
     if (!collectAllTerminalIds(layouts).has(tid)) {
+      log.debug('attach gate declined: terminal not referenced by any layout', {
+        terminalId: tid,
+        paneId: paneIdRef.current,
+        intent,
+      })
       return
     }
     const term = termRef.current

src/store/terminalDetachMiddleware.ts

@@ -12,6 +12,15 @@ type PanesStateSlice = { panes: { layouts: Record<string, PaneNode | undefined>
  * reported dead or unrecoverable (terminal.inventory / terminals.changed).
  * There is no live subscription to release, and the server replies with an
  * error for terminal.detach on a non-existent terminal — so skip them.
+ *
+ * MAINTENANCE WARNING: this skip-list is maintained BY HAND. If you add a
+ * new reducer/action that removes terminalIds from layouts because the
+ * SERVER already reported those terminals dead, you MUST register it here —
+ * otherwise this middleware sends a redundant terminal.detach for each one
+ * and the server answers with an error (harmless but noisy). Conversely,
+ * never register an action that removes a LIVE terminal from the layouts:
+ * skipping it would leak the server-side subscription — the exact bug this
+ * middleware exists to prevent (see PR #534).
  */
 const skipDetachActionTypes = new Set<string>([
   clearDeadTerminals.type,