QA: Declarative UI — json-render — AWS Strands (Python)

Prerequisites

• Demo reachable at /demos/declarative-json-render
• agent_server.py running and healthy; the shared agent at / cannot emit the flat spec, so a dedicated prompt-specialized agent is mounted at /byoc-json-render/
• src/app/api/copilotkit-declarative-json-render/route.ts proxies to ${AGENT_URL}/byoc-json-render/ (AGENT_URL defaults to http://localhost:8000)
• OPENAI_API_KEY set for the agent backend
• @json-render/core + @json-render/react present in package.json (pinned to 0.18.0)

Test Steps

1. Page load

• Navigate to /demos/declarative-json-render.
• Chat composer is visible.
• Three suggestion pills appear with titles: "Sales dashboard", "Revenue by category", "Expense trend".
• No console errors.

2. Sales dashboard suggestion

• Click the "Sales dashboard" suggestion.
• Within 60 seconds, a data-testid="json-render-root" wrapper appears in the assistant bubble.
• A data-testid="metric-card" renders inside the wrapper.
• A chart (data-testid="bar-chart" or data-testid="pie-chart") renders inside the wrapper.
• Nested children of the MetricCard (the BarChart in the Sales Dashboard worked example) render — they are NOT silently dropped.
• No raw JSON text is shown once rendering finishes — the streaming JSON is replaced by components.

3. Revenue by category

• Click the "Revenue by category" suggestion.
• Within 60 seconds, a data-testid="pie-chart" renders with multiple category slices + legend.
• No useVisibility must be used within a VisibilityProvider console error (<JSONUIProvider> must wrap <Renderer>).

4. Expense trend

• Click the "Expense trend" suggestion.
• Within 60 seconds, a data-testid="bar-chart" renders with month labels.

5. Free-form prompt

• Type "Show me a metric for quarterly revenue" and send.
• Verify at least one metric-card renders; no console errors.

6. Multi-turn

• After a previous render is visible, send a follow-up prompt ("Now break that down by region").
• A new assistant message appears with a new json-render rendering — prior renders stay in the transcript.

7. Malformed output handling

• If the agent ever replies with non-JSON text (force it by asking "tell me a joke"), the chat falls back to rendering that raw text via the default assistant bubble. No crash, no stuck spinner.

Expected Results

• Suggestion renders land within 60 seconds. Budget is slightly higher than the hashbrown demo because a JSON { root, elements } spec is more verbose than hashbrown's token stream.
• No uncaught errors in the console.
• Streaming falls back to plain text until the JSON parses, then swaps to rendered components.

Integration notes

• The canonical flat-spec ({ root, elements }) prompt lives in src/agents/byoc_json_render.py; the byoc_ prefix on the backend module and the /byoc-json-render/ HTTP mount are deliberate and stay.
• A legacy src/app/api/copilotkit-byoc-json-render/route.ts is still present alongside the canonical one; the demo page uses the declarative- route.
• The nested-children and JSONUIProvider checks in steps 2 and 3 are the regression guards for PR #4271 — keep them in every pass.