fix(web): follow a blank session's preset switch in the slash catalog

Presets own the rows that decide what a session's `/` menu contains, but
both browser catalogs cache per session and had no invalidation edge for a
recompose: `commands/changed` is registry-wide and recomposing registers
nothing, so the menu kept serving the composition the session no longer ran.

The host stream now frames the logged `agent-preset/selected` commit as
`host/session-preset-changed`; the runtime bridges it to the typed
`session/preset-changed` event, `ui-command` soft-refreshes that session's
directory key and `ui-skill` invalidates its catalog entry.

Reaching the host on a second switch was a separate defect: the list-row
identity guard compared every summary field except `agentPreset`, and the
merge keeps the row's `updatedAt`, so a switched row looked unchanged and
served its cached instance forever. The hero chip compares the pick against
that row, so switching back to the creation-time preset sent no RPC at all.

packages/client/runtime/src/client/index.ts

@@ -181,6 +181,18 @@ declare module 'cordis' {
      * @mode emit
      */
     'models/changed'(): void
+    /**
+     * One session's agent preset changed (host/session-preset-changed
+     * passthrough), so everything its composition decides — the command
+     * catalog, the skill catalog — is stale for that session and no other.
+     * Every connected client observes it, not only the one that issued the
+     * switch. Subscribers refetch their own session-keyed caches; the frame
+     * carries no catalog.
+     * @mode emit
+     * @param sessionId - the session whose composition changed.
+     * @param agentPreset - the preset it now runs.
+     */
+    'session/preset-changed'(sessionId: SessionId, agentPreset: string): void
     /**
      * A connection generation was (re-)established. Wire-derived caches must
      * treat their state as stale and repull (commands directory; the queue
@@ -244,6 +256,9 @@ export function apply(ctx: Context): void {
       // and model surfaces) subscribe on ctx.
       const frame = envelope.payload
       if (frame.type === 'host/commands-changed') ctx.emit('commands/changed')
+      else if (frame.type === 'host/session-preset-changed') {
+        ctx.emit('session/preset-changed', frame.sessionId, frame.agentPreset)
+      }
       else if (frame.type === 'host/settings-changed') ctx.emit('settings/changed', frame.ns)
       else if (frame.type === 'host/credentials-changed') ctx.emit('credentials/changed', frame.ref)
       else if (frame.type === 'host/models-changed') ctx.emit('models/changed')

packages/client/runtime/src/client/sessions/manager.ts

@@ -1005,7 +1005,7 @@ export class SessionManager {
       const prev = this.entryCache.get(entry.sessionId)
       if (
         prev !== undefined && prev.updatedAt === entry.updatedAt && prev.running === entry.running
-        && prev.blank === entry.blank
+        && prev.blank === entry.blank && prev.agentPreset === entry.agentPreset
         && prev.parentSessionId === entry.parentSessionId && prev.cwd === entry.cwd
         && prev.origin === entry.origin && prev.title === entry.title && prev.depth === entry.depth
         && prev.pendingInteraction === entry.pendingInteraction