QA: Frontend Tools (In-App Actions) — LangGraph (Python)

Prerequisites

• Demo is deployed and accessible at /demos/frontend-tools on the dashboard host
• Agent backend is healthy (/api/copilotkit GET returns langgraph_status: "reachable"); OPENAI_API_KEY is set; LANGGRAPH_DEPLOYMENT_URL points at a deployment exposing the frontend_tools graph (registered under agent name frontend_tools)
• The backend frontend_tools.py registers NO server-side tools — the agent forwards the frontend tool schema at runtime; the browser owns the handler
• Frontend registers exactly ONE tool via useFrontendTool: change_background (parameter: background: string — a CSS background value, colors or gradients). Handler sets local React state and returns { status: "success", message: "Background changed to …" }

Test Steps

1. Basic Functionality

• Navigate to /demos/frontend-tools; verify the page loads within 3s
• Verify the background container (data-testid="background-container") is visible, full-screen, flex-centered
• Verify the initial background value is var(--copilot-kit-background-color) (the theme default) — inspect the container's inline style.background
• Verify the CopilotChat panel renders centered (max width 4xl, rounded-2xl corners) inside the background container
• Send "Hello"; verify the agent responds with plain text within 10s and does NOT call change_background

2. Feature-Specific Checks

Suggestion Pills

• Verify the "Change background" suggestion pill is visible above the input
• Verify the "Sunset theme" suggestion pill is visible
• Click the "Change background" pill; verify it sends the verbatim prompt "Change the background to a blue-to-purple gradient."

change_background — Successful Invocation

• After clicking the "Change background" pill (or typing "Change the background to a linear gradient from indigo to pink"), verify within 15s that the agent invokes the change_background tool
• Verify the data-testid="background-container" element's inline style.background mutates from var(--copilot-kit-background-color) to a CSS gradient string containing linear-gradient (or radial-gradient)
• Verify the change is visually reflected (color/gradient swap is instant, no flash)

Round-Trip — Agent References Tool Return Value

• Immediately after the background changes, verify the agent emits a follow-up assistant message that acknowledges the change
• Verify the follow-up message text references the new background value OR echoes the "Background changed to <value>" success message (confirming the agent consumed the handler's return payload, not just triggered the tool blindly)
• Ask "What color is the background right now?"; verify the agent replies with a description consistent with the last change_background call's argument (demonstrates the agent received the handler's return string into context)

Second Invocation — State Persistence

• Ask "Change it to a sunset gradient with orange and pink"; verify the background mutates again to a new gradient
• Verify the previous gradient is fully replaced (not layered)
• Ask "Now make it solid dark blue"; verify style.background becomes a solid color value (e.g. #00008b, darkblue, or rgb(...)) — no gradient keyword

3. Error Handling

• Send "Change the background to banana"; verify the agent either (a) calls change_background with a valid CSS fallback (e.g. yellow, #FFE135) and the container updates, or (b) declines politely without calling the tool — either is acceptable, but the UI must not crash
• Send an empty message; verify it is a no-op
• Send a ~500-character prompt unrelated to backgrounds; verify the agent responds normally without invoking change_background
• Open DevTools → Console; verify no uncaught errors, no Zod parse failures, no useFrontendTool warnings

Expected Results

• Chat loads within 3 seconds; first change_background invocation completes within 15 seconds of prompt
• The [data-testid="background-container"] inline style.background updates in real time as the tool is invoked
• Agent's follow-up reply demonstrably uses the handler's returned message field (round-trip verified)
• Multiple sequential invocations replace the background cleanly with no visual artifacts
• No uncaught console errors; no broken layouts