Preview

Bring up the running app and let the user drive it themselves to judge the change, then act on their verdict.

Step 1: Determine Scope

Resolve what to preview using the first match:

User-specified — the user says what to look at. Use that.
PR — a PR URL or number is provided. Fetch its details and read the changed code.
Conversation context — prior conversation contains recent work. Extract what changed, where it lives, and the expected behavior.
App-level discovery — fresh context with no prior work. Examine entry points, routes, and the README to identify the app's core user-facing flows.

If the resolved scope has no user-visible surface to try (a CLI-only change, a library with no entry point, backend work with no UI to look at), present this message: "Nothing to preview — ." Then use the TaskList tool and proceed to any remaining task.

Step 2: Determine Launch Approach

Check for a project-specific skill or MCP tool that launches the app, and use it if present. Otherwise use the fallback for the surface type: