feat(control-plane): getGithubApp MCP tool hands the agent the App install link

[spacedragon]

What

Adds one read tool to the admin MCP catalog: getGithubApp → GET /github/app. It returns whether the deployment has a GitHub App, its slug, and a fresh installUrl — the signed, one-shot, org-bound link to install the App on GitHub for the caller's organization.

• http/mcp/tools.ts: the tool, placed before listGithubInstallations, with a description that tells the model when to call it (installations empty, or none covering the repository's owner) and to hand the link to the user verbatim.
• test/integration/mcp.route.test.ts: added to the GitHub-gated set so the route-reach guard probes it against the GitHub-configured app.
• docs/designs/agent-assistant.md §6.2: catalog row.

Why

Seen in a webchat session with the built-in agent: when the GitHub App was not installed, the create-agent flow could only point at a console tab. No tool returned the install link, and the skill cannot construct it, because the route mints a signed state per call that the setup callback needs to bind the installation to the org.

Reviewer notes

• Read tool, GET only. The route keeps its own denyViewerWrite gate (minting the link starts a connection change); a viewer's 403 is relayed as-is and the tool description says an editor/owner has to open the link.
• Each call mints a new state row (15-minute TTL, consumed once). The paired skill change tells the agent to call it only when an installation is actually missing and to fetch a fresh one rather than reuse an old link.
• Pairs with feat: a missing GitHub App installation gets the install link, not a console page agentconnect-skill#5, which makes the code-reviewer template use it.

Verification

• vitest run src/http/mcp/tools.test.ts — 37 passed.
• vitest run --project integration test/integration/mcp.route.test.ts — 34 passed (includes "every registered tool reaches a real route").
• Prettier clean on the three files.

🤖 Generated with Claude Code

[agentconnect-md-test]

Reviewed revision b564f074a790f51f68757a67bee7c22477228c88. No blocking regressions found. The new tool reuses the caller-scoped GitHub App route, preserves its viewer restriction, and returns the existing signed, one-shot install link unchanged.

git diff --check passed. The focused MCP unit tests could not run: dependencies are absent, and pnpm’s automatic install failed on a restricted filesystem path. The integration suite was not run.

_{sent by review-bot (Codex · gpt-6-astra) · open in session}