A pair of demos that exercise the same backend reasoning graph but
differ only in whether the frontend overrides the
`messageView.reasoningMessage` slot.
Backend (src/agents/reasoning_agent.py): uses a reasoning-capable OpenAI
model (gpt-5-mini by default, override via OPENAI_REASONING_MODEL) routed
through the Responses API so the model's chain-of-thought streams as
AG-UI REASONING_MESSAGE_* events with `role: "reasoning"`. The prompt
asks for a concrete physics answer, which reliably triggers reasoning;
meta-prompts like "show your reasoning step by step" produce no
reasoning summary because the model recognizes those as a request to
reveal chain-of-thought (which it refuses).
Frontend:
- reasoning-default/ — no slot override; built-in
CopilotChatReasoningMessage renders the "Thinking… / Thought for X"
header with an expandable content region.
- reasoning-custom/ — overrides `messageView.reasoningMessage` with a
ReasoningBlock (amber banner with `data-testid="reasoning-block"`).
The label flips from "Thinking…" while streaming to "Agent reasoning"
once the stream settles.
Suggestions live in their own files (per the page-as-entry-point
convention). Both demos share `agent="reasoning-default"` /
`agent="reasoning-custom"` against the same `reasoning_agent` graph,
registered in api/copilotkit/route.ts.
Removed:
- src/app/demos/agentic-chat-reasoning/ — replaced by reasoning-custom/
for naming clarity.
- src/app/demos/reasoning-default-render/ — earlier draft of the Default
demo with a slightly different page name.
- tests/e2e/agentic-chat-reasoning.spec.ts — replaced by
reasoning-custom.spec.ts.
Tyler Slaton