Auto-Capture: Claude Code Adapter

Relationship to Upstream Skill

This adapter implements the session-end capture behavior defined by the upstream auto-capture skill by Jared Irish. The base skill is a behavioral protocol — it describes when and what to capture during interactive session closes. This adapter is the concrete Claude Code binding: a Stop-hook script that fires the same capture behavior automatically when a session ends without a verbal trigger. The upstream skill and this adapter are complementary; install both for full coverage.

Problem

The base auto-capture skill requires a verbal trigger ("wrap up", "park this") to fire. In practice, many Claude Code sessions end without that trigger — the user closes the terminal, hits Ctrl+C, or simply walks away. Those sessions and their decisions are lost.

What This Adapter Adds

This adapter uses Claude Code's hook system to run a capture script automatically at session end. It complements the base auto-capture skill:

• Base auto-capture handles interactive session-close captures (ACT NOW items, session summaries) when the user explicitly wraps up.
• This adapter handles ambient capture when the session ends without an explicit trigger (terminal close, timeout, Ctrl+C).

Together they ensure no valuable session falls through the cracks.

How It Works

1. Claude Code fires a Stop hook at session end, passing the transcript path and session metadata via stdin as JSON.
2. The hook script (session-end-capture.mjs) reads the transcript, filters out short or agent-only sessions, and formats the content.
3. The formatted transcript is POSTed to the Open Brain REST ingest endpoint (or smart-ingest edge function) for automatic thought extraction.
4. Failed captures are saved to a local retry queue and retried on subsequent session ends.

Skip Heuristics

Not every session is worth capturing. The hook skips:

• Sessions with fewer than 3 user turns (too short to contain decisions)
• Agent-only sessions (sub-agent work, automated tooling)
• Sessions containing restricted content (matched against sensitivity patterns)
• Session-end reasons that are not terminal (clear, resume)

Installation

Prerequisites

Install the base auto-capture skill first. This adapter extends it — it does not replace it.

Steps

1. Copy session-end-capture.mjs to your project or a shared scripts directory.

2. Register the hook in your Claude Code settings (.claude/settings.json or global ~/.claude/settings.json):

   {
     "hooks": {
       "Stop": [
         {
           "matcher": "",
           "hooks": [
             {
               "type": "command",
               "command": "node /path/to/session-end-capture.mjs"
             }
           ]
         }
       ]
     }
   }

3. Set environment variables (in .env.local or your environment):

   SUPABASE_URL=https://<project-ref>.supabase.co
   MCP_ACCESS_KEY=your-access-key

4. Restart Claude Code to pick up the hook.

5. End a test session with at least 3 user messages and verify a capture appears in your Open Brain thoughts.

Adapting the Script

The included session-end-capture.mjs is a reference implementation. Adapt it to your setup:

• Ingest endpoint: Update the URL construction if your REST API or smart-ingest function is deployed at a different path.
• Sensitivity patterns: Add a config/sensitivity-patterns.json file with regex patterns for restricted content detection, or remove the check if you don't need it.
• Retry queue: The script saves failed captures to data/capture-retry-queue/ and retries them on subsequent runs. Adjust RETRY_MAX_ATTEMPTS and RETRY_BATCH_SIZE as needed.
• Hard timeout: The script exits after 25 seconds to avoid blocking Claude Code shutdown. Adjust HARD_TIMEOUT_MS if your network is slower.

Output

When working correctly:

• Every meaningful Claude Code session (3+ user turns, non-agent, non-restricted) is automatically ingested into Open Brain for thought extraction.
• Failed captures are queued locally and retried on subsequent session ends.
• Short, agent, and restricted sessions are silently skipped.
• All outcomes are logged to logs/ambient-capture.log for debugging.

Notes

• This adapter is designed to be non-blocking. All errors are caught and logged — the hook never prevents Claude Code from shutting down.
• The base auto-capture skill and this adapter are complementary. The skill handles interactive captures with ACT NOW items; the adapter handles ambient background capture of the full session transcript.
• Tool names vary by client and connector. The hook script uses the REST API directly rather than MCP tools, so it works regardless of which MCP connector is active.