Dumbwaiter MCP

Dumbwaiter MCP: Wait-for-Change

Goal: give Claude a single, stable way to “wait until X happens” on a code host (GitHub now; GitLab next). This skill teaches Claude when and how to use the Dumbwaiter MCP server’s tools.

Prerequisites

• Server: this repo builds a stdio MCP server (cargo build && target/debug/dumbwaiter-mcp).
• Auth: export GITHUB_TOKEN=… (repo read permissions are sufficient for commit statuses).
• Persistence (optional): DUMBWAITER_DB to override ./state/dumbwaiter.sqlite.
• Await settings (optional): DUMBWAITER_AWAIT_TTL_SECS (default 900), DUMBWAITER_ENGINE=1 to enable the background engine (legacy alias DUMBWAITER_WATCHER=1 still works).

When to use this skill

• You need to pause orchestration until PR checks turn green, a PR is merged, or checks fail.
• You want durable waits with a wait_id, cancellable and recoverable after restarts.
• You want progress updates visible to the host via MCP notify_progress.

Tools overview

• wait.start → returns { wait_id } for a condition on a selector
• wait.status → returns current state: pending|satisfied|failed|timeout|cancelled|unknown
• wait.cancel → cancels a pending wait
• wait.await → polls provider with exponential backoff; emits progress notifications; resolves to terminal state or timeout

Selectors and conditions (GitHub)

• selector: { "owner": "ORG", "repo": "REPO", "pr": 123 }
• Supported condition tokens:
  • checks_succeeded — combined status success
  • checks_failed — combined status failure/error
  • pr_merged — merged flag true
  • pr_approved — at least one approved review
  • changes_requested — an open review with changes requested
  • workflow_completed — at least one completed workflow run
  • comment_received — any new PR comment/review/reaction event (see streaming section below)

For comment_received, optional filters refine which events count. If omitted, since defaults to the wait's created_at timestamp so Dumbwaiter streams everything posted after the wait was created.

Happy-path flow

1. Start wait
   • name: wait.start
   • arguments: { "provider": "github", "selector": {…}, "condition": "checks_succeeded" }
   • capture wait_id
2. Await
   • name: wait.await
   • arguments: { "wait_id": "…" }
   • Observe progress notifications; handle final result
3. Query or cancel as needed
   • wait.status or wait.cancel

Guidelines

• Prefer wait.await when a host can display progress; otherwise poll with wait.status on an interval < backoff cap (default 30s).
• Always report final state back to the orchestrator and link the wait_id in logs/notes.
• On auth errors or rate limits, surface a clear, actionable message; do not retry aggressively (respect backoff).
• On timeouts, return timeout with elapsed seconds; let the caller decide next steps.
• Security: never echo tokens; require least scopes.

Streaming GitHub comment events

Set condition to comment_received plus optional filters:

{
  "provider": "github",
  "selector": { "owner": "acme", "repo": "widgets", "pr": 42 },
  "condition": "comment_received",
  "filters": {
    "since": "2025-01-01T00:00:00Z",
    "include_bots": true,
    "author_allowlist": ["alice"],
    "author_denylist": ["bot"]
  }
}

wait.await emits notify_progress for every matching comment/review/reaction (body + URL + reaction counts + code context) before returning the terminal payload that mirrors the streamed events. Use this when an orchestrator needs to react to each individual discussion event.

Examples

• “Wait for PR 42 in acme/widgets until checks pass.”
  • start → { provider: "github", selector: { owner: "acme", repo: "widgets", pr: 42 }, condition: "checks_succeeded" }
  • await → { wait_id }
• “Stream every new comment on PR 42 since midnight UTC.”
  • start → { provider: "github", selector: { owner: "acme", repo: "widgets", pr: 42 }, condition: "comment_received", filters: { since: "2025-01-01T00:00:00Z", include_bots: true } }
  • await → receives per-comment progress events plus the final summary payload

Troubleshooting

• unknown status: the wait_id was not found (DB purge or wrong project).
• No progress events: confirm host supports MCP notifications and server is connected.
• Auth failures: ensure GITHUB_TOKEN is set and valid for the target repo.