fix(tui): release the adapter-registration listener on channel detach

Review follow-up: the llm/adapters-updated listener's disposer was
discarded, leaving it firing (harmlessly, behind isDisposed()) between
TUI shutdown and fiber disposal, asymmetric with the sibling channel
listeners. The controller now exposes detach(), and the channel's
detachListeners() calls it on both the dispose() and startup-failure
paths.

packages/ui/tui/src/chat/model-command.ts

@@ -37,6 +37,8 @@ export interface ModelController {
   resetContextResolution(): void
   /** Forget the tracked selector overlay (shutdown). */
   clearOverlay(): void
+  /** Remove the adapter-registration listener (channel detach). */
+  detach(): void
 }
 
 type ContextResolution =
@@ -88,8 +90,9 @@ export function createModelController(deps: ModelControllerDeps): ModelControlle
   // The wait cannot go stale against `target.current`: every target change
   // re-enters resolveContextWindow, which clears it. A commit that still
   // lacks the route parks the resolution again rather than erroring, so
-  // unrelated topology changes stay silent.
-  ctx.on('llm/adapters-updated', () => {
+  // unrelated topology changes stay silent. The disposer rides the channel's
+  // detachListeners() through detach(), matching the sibling listeners.
+  const disposeAdapterListener = ctx.on('llm/adapters-updated', () => {
     if (deps.isDisposed() || !awaitingAdapter) return
     resolveContextWindow(target.current)
   })
@@ -206,5 +209,8 @@ export function createModelController(deps: ModelControllerDeps): ModelControlle
     clearOverlay(): void {
       modelOverlay = undefined
     },
+    detach(): void {
+      disposeAdapterListener()
+    },
   }
 }