feat(web): rewrite subagent conversations for FIFO activation

packages/client/ui-conversation/src/client/contract/slots.ts

@@ -334,8 +334,8 @@ export type ComposerBarProps =
  */
 export interface ComposerChainProps {
   interactions: readonly PendingInteraction[]
-  /** A catalog-addressed child whose exact parent Agent is unavailable. */
-  subagentReadOnly: boolean
+  /** Current conversation facts for feature-owned takeover selectors. */
+  session: ConversationSnapshot | undefined
 }
 
 /**

packages/client/ui-conversation/src/client/skeleton/ConversationRoot.tsx

@@ -19,7 +19,6 @@ export function ConversationRoot({
   const openState = useSession(s => s.openState)
   const composerPhase = useSession(s => s.composerPhase)
   const pending = useSession(s => s.pending) ?? []
-  const subagentReadOnly = useSession(s => s?.subagent?.parentAvailable === false) ?? false
   const session = useSession(s => s)
   const inputState = useInput(s => s)
   const cwd = useSessions(s => sessionId === undefined ? undefined : s.byId[sessionId]?.cwd)
@@ -154,7 +153,7 @@ export function ConversationRoot({
   const phase = settling ? 'settling' : hero ? 'hero' : 'active'
   const composer = renderSlotChain(
     'conversation.composer',
-    { interactions: pending, subagentReadOnly },
+    { interactions: pending, session },
     { fallback: composerBar, overlay: true },
   )