/create customizer: randomize tool loops on second 'shuffle' turn, card stuck at "Randomizing…"

[GeneralJerel]

Summary

On the /create customizer route, the first shuffle / randomize request from the chat works fine. On the second user turn that asks for a randomize, the randomize tool card in the chat gets stuck at "Randomizing…" and the agent appears to loop (never returns a final message, stop button stays visible).

Repro

1. Navigate to /create.
2. In the theme assistant chat, send shuffle (or any prompt that triggers randomize). ✅ Works — the card transitions to "Randomized" and the agent replies with a bullet summary of what changed.
3. Send shuffle again in the same thread. ❌ The card shows "Randomizing…" indefinitely; the agent never produces a text reply.

What's been tried

• Tightened system prompt to require "call randomize EXACTLY ONCE per user request". gpt-5.4 still re-calls.
• Added a 2-second time-window guard in useRandomizeCoAgent (apps/ui/src/routes/create/agent-bridge/use-randomize-coagent.ts) — insufficient: gpt-5.4's per-call latency exceeds 2s in practice, so the window misses subsequent loop calls.
• Replaced the time window with a turn-scoped flag that resets when useCopilotChat().isLoading transitions true → false (see commit 6936b94). The flag is set on the first successful call of the run; any re-call in the same run returns an "already done" tool result. Also wrapped the handler in try/catch so unhandled exceptions still return a tool result rather than leaving the card stuck.
• User report: this fix did not resolve the issue — the second-turn loop / stuck card still reproduces.

Hypotheses to investigate

1. The handler may never actually be invoked on the second turn (card stays at "Randomizing…" = status never leaves inProgress), which would mean the fix is moot. Add a console.log at the top of the handler to confirm whether it's even entered on the second turn.
2. The tool-call event plumbing may be racing with the re-render that setParams triggers on the first call, dropping the tool result for the follow-up call. Worth checking whether useCopilotAction's registration is being invalidated between the call site and result delivery.
3. The isLoading signal from useCopilotChat() may not be reliable here (multi-agent / LangGraph agent) — if it never goes false between turns, the flag never resets; if it flaps mid-run, the flag resets too early. Log its transitions to verify.
4. Server-side (apps/agent/main.py, gpt-5.4 via LangGraph) may not be sending the follow-up tool result back to the client in a shape the frontend can consume. Check the AG-UI event stream for the second turn.

Next steps

• Add instrumentation (handler entry log, isLoading transition log, tool-call event log) to determine which of the above is actually happening.
• If it's (3), fall back to tracking user-message count via useCopilotChat().visibleMessages and reset the guard when the user-message count increments.
• Consider enforcing "max 1 randomize per turn" on the server (LangGraph middleware) as a belt-and-suspenders fix, since client-side guards rely on cooperative LLM behavior.

References

• Tool file: apps/ui/src/routes/create/agent-bridge/use-randomize-coagent.ts
• Agent config: apps/agent/main.py
• Tool card renderer: apps/ui/src/routes/create/agent-bridge/tool-call-card.tsx
• Branch: shadify-port (commits 36011f6, 6936b94)