d07363cbe5
Bridges Molecule A2A traffic into a Claude Code session via MCP. Inbound A2A messages from watched workspaces surface as conversation turns (notifications/claude/channel); replies route back through the existing POST /workspaces/:id/a2a endpoint via the reply_to_workspace MCP tool. Architecture: - Polling-based inbound (uses /activity?since_secs= shipped in molecule-core PR #2300). Works through every NAT/firewall, no tunnel required — optimized for laptop-launched Claude Code sessions vs the existing push-based external-agent flow that needs ngrok. - Per-workspace bearer auth (MOLECULE_WORKSPACE_TOKENS, comma-separated to match MOLECULE_WORKSPACE_IDS). Same token covers /activity (read) and /a2a (write). - Singleton lock at ~/.claude/channels/molecule/bot.pid prevents two channel servers racing the dedup state. - Dedup by activity.id; 30s overlap window over a 5s poll interval protects against missed ticks (laptop sleep, transient network blips). v0.1 ships: - .claude-plugin/plugin.json, .mcp.json, package.json, LICENSE (Apache-2.0) - server.ts: MCP server with notification emission + reply_to_workspace tool - README: install + .env config + architecture notes + v0.2 roadmap v0.1 explicit non-goals (tracked in README): - No push-mode inbound (requires tunnel; deferred to v0.2) - No pairing flow (manual .env tokens; canvas pairing in v0.2) - No file-attachment download (URLs surface in meta; host fetches on-demand) - No outbound channel-init (only replies; start_workspace_chat in v0.2) Mirrors the architecture of @claude-plugins-official/telegram v0.0.6 (MCP notification contract: notifications/claude/channel with {content, meta}) so the host's existing channel-handling logic works without custom adapters. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
137 lines
6.4 KiB
Markdown
137 lines
6.4 KiB
Markdown
# molecule-mcp-claude-channel
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Claude Code channel plugin for [Molecule AI](https://moleculesai.app). Bridges Molecule A2A traffic into a Claude Code session: peer messages from your watched workspaces surface as conversation turns, and your replies route back through Molecule's A2A.
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## What it does
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When you launch Claude Code with this plugin enabled and configure it to watch one or more Molecule workspaces, every A2A message your watched workspaces receive shows up in the session as a user-turn. You reply normally; the plugin's MCP `reply_to_workspace` tool sends the response back through Molecule.
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```
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Molecule peer ──A2A──> [your workspace] ──poll──> [this plugin] ──MCP notification──> Claude Code session
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^ │
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└────────── POST /workspaces/:id/a2a ◄── reply_to_workspace tool ──┘
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```
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No tunnel. No public endpoint. The plugin polls your tenant for new A2A activity (using the `?since_secs=` filter on `/workspaces/:id/activity`); replies POST back to `/workspaces/:peer_id/a2a` via the same bearer token.
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## Install
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```bash
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claude --channels plugin:molecule@Molecule-AI/molecule-mcp-claude-channel
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```
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On first launch the plugin creates `~/.claude/channels/molecule/` and exits with a config-missing error pointing at `.env`. Fill it in:
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```
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# ~/.claude/channels/molecule/.env
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# Required
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MOLECULE_PLATFORM_URL=https://your-tenant.staging.moleculesai.app
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MOLECULE_WORKSPACE_IDS=ws-uuid-1,ws-uuid-2
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MOLECULE_WORKSPACE_TOKENS=tok-1,tok-2
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# Optional
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MOLECULE_POLL_INTERVAL_MS=5000 # default 5s
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MOLECULE_POLL_WINDOW_SECS=30 # default 30s — overlap protects against missed ticks
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```
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The `.env` file is `chmod 600` after first read; tokens never appear in environment-block-style `claude doctor` dumps.
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Re-launch Claude Code:
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```bash
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claude --channels plugin:molecule@Molecule-AI/molecule-mcp-claude-channel
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```
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You should see on stderr:
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```
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molecule channel: connected — watching 2 workspace(s) at https://your-tenant.staging.moleculesai.app
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workspaces: ws-uuid-1, ws-uuid-2
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poll: every 5000ms with 30s window
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```
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## Getting workspace_id + token
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Every Molecule workspace has a workspace-scoped bearer that authenticates against `/activity` (read) and `/a2a` (write). Two ways to get one:
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### From Canvas (recommended)
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1. Open the workspace in Canvas
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2. Settings tab → "Auth tokens" → **Create channel token**
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3. Copy the workspace_id (UUID at the top) and the token (shown once)
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### From the API
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```bash
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curl -X POST "$MOLECULE_PLATFORM_URL/admin/workspaces/$WORKSPACE_ID/tokens" \
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-H "Authorization: Bearer $ADMIN_TOKEN" \
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-H "Content-Type: application/json" \
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-d '{"label": "claude-channel"}'
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```
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## How replies work
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When a peer's message lands in your session, the meta block carries the routing data Claude needs:
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```json
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{
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"method": "notifications/claude/channel",
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"params": {
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"content": "Hey, can you take a look at this? <issue body>",
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"meta": {
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"source": "molecule",
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"workspace_id": "ws-uuid-1",
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"watching_as": "ws-uuid-1",
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"peer_id": "ws-uuid-pm-coordinator",
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"method": "user_message",
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"activity_id": "act-...",
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"ts": "2026-04-29T..."
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}
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}
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}
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```
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Claude can call `reply_to_workspace({peer_id, text})` to send the response back. If only one workspace is watched, `workspace_id` is implicit. Multi-workspace setups need the watched id explicitly.
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## Architecture notes
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### Why polling instead of push?
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The existing external-agent integration in Molecule uses **push**: register an inbound URL, platform POSTs A2A to that URL. That's lower latency but requires a tunnel (ngrok/Cloudflare) or a static IP — non-trivial for a laptop-launched Claude Code session.
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This plugin uses **polling** as the default because it works through every NAT/firewall with zero infra. The cost is up to `MOLECULE_POLL_INTERVAL_MS` (default 5s) of inbound latency. For production setups where lower latency matters, a future `MOLECULE_INBOUND_MODE=push` can opt into the existing register-and-receive flow.
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### Why `since_secs=30` overlapping a `5s` poll interval?
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A single missed tick (transient network blip, GC pause, laptop sleep) shouldn't lose messages. The plugin re-fetches the last 30 seconds on every poll and dedups by `activity_id`, so 25 seconds of overlap is the recovery margin. Set `MOLECULE_POLL_WINDOW_SECS` higher for noisier networks.
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### Singleton lock
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Only one channel server can poll a given workspace set at a time — multiple instances would race the dedup state and double-deliver. The plugin maintains a PID file at `~/.claude/channels/molecule/bot.pid` and on startup kills any stale predecessor (matches the telegram channel pattern).
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### File attachments
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A2A messages can carry `Part` entries with `url` and `media_type`. The MVP delivers attachments by-reference (URL surfaces in the meta block, Claude can fetch via the workspace_secrets-scoped token); inline image-content delivery (mirroring telegram's `image_path` mechanism) is a v0.2 feature.
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## Limitations (v0.1)
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- **Polling-only inbound.** No push mode yet; latency floor is `MOLECULE_POLL_INTERVAL_MS`.
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- **No pairing flow.** Tokens are configured manually via `.env`; no canvas-side approval handshake. Add `MOLECULE_ACCESS_MODE=pair` (mirroring telegram) in v0.2.
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- **No file-attachment download.** URLs surface in the meta block; the host fetches on-demand.
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- **No outbound channel-init.** The plugin only sends replies (in response to inbound A2A); starting a fresh A2A conversation initiated FROM the channel side requires a future `start_workspace_chat` tool.
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## Compatibility
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- **molecule-runtime/workspace-server**: requires the `?since_secs=` query parameter on `GET /workspaces/:id/activity` (shipped in molecule-core PR #2300, available staging-onward).
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- **Claude Code**: tested against the channel-plugin contract that expects `notifications/claude/channel` with `{content, meta}` (matches `@claude-plugins-official/telegram` v0.0.6).
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- **bun**: the MCP server runs under bun for fast startup; `package.json` `start` does `bun install --no-summary && bun server.ts` so no global install needed.
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## Contributing
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Single-file MCP server. The whole bridge lives in `server.ts`. Open issues at [Molecule-AI/molecule-mcp-claude-channel](https://github.com/Molecule-AI/molecule-mcp-claude-channel/issues).
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## License
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Apache-2.0 — see LICENSE.
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