session-knowledge

Claude Code's memory is scoped per project directory. Your history isn't.

Every session you've ever run is already on disk in ~/.claude/projects/**/*.jsonl — every decision, every command that worked, every credential you pasted. But open a session in a different directory and none of it is reachable. You re-ask questions you already answered, and re-implement integrations you already wrote.

This indexes all of it and hands Claude 13 MCP tools to search it. You just ask normally.

What was the retry logic in that deploy script? Which DATABASE_URL did I actually use for staging? Before I write the Stripe integration — has anyone here already done payment auth?

Pure Python standard library. No third-party dependencies, no embeddings, no API calls, nothing leaves your machine.

git clone https://github.com/nameforjt-afk/session-knowledge.git
cd session-knowledge
bash install.sh

Restart Claude Code. Done.

⚠️ Read this before installing

The index lives in ~/.claude/session-index/ and it contains plaintext credentials scraped from your sessions. That is the precondition for "which key did I use here" to work at all.

Never commit that directory, never sync it to cloud storage, never send it to anyone. This repo's .gitignore covers the default location, but if you relocate it that's on you.

The full-text index itself is redacted: common credential shapes (API keys, Bearer tokens, JWTs, GitHub PATs, passwords inside connection strings) are replaced with ⟦SECRET:fingerprint⟧ before they are written. Plaintext lives only in vault.db at mode 0600, and only an explicit creds get returns it.

Redaction is pattern matching, not magic. Custom-format secrets can slip through. verify-redaction spot-checks for leaks.

What it actually solves

Four things, in rough order of how often they save you:

1. "Have I already built this?" — Search by external service, not by function name. grep only works if you already know the string to search for (you need to know it's tenant_access_token before you can grep for Feishu auth). Capability tags don't require that.

2. "How did we decide this?" — The rationale is buried in thousands of past instructions. Full-text search over them, filterable to just your own instructions.

3. "How did that command go again?" — Every Bash and MCP call, with arguments and results. Filter to only the ones that failed, to recall the traps.

4. "Which value does this key take?" — Same variable name routinely has several real values (multiple apps, dev vs prod, two tables). It returns all candidates ranked, with the call site each came from, rather than silently picking one.

Usage

Day to day: nothing

A hook refreshes the index incrementally on each Claude Code start (async, non-blocking, usually 1–2s). Ask questions normally; Claude reaches for the tools on its own.

CLI

python3 -m sessionmcp.cli index                     # incremental refresh
python3 -m sessionmcp.cli stats                     # index health check

python3 -m sessionmcp.cli search "deploy timeout"   # full text (multi-word = AND)
python3 -m sessionmcp.cli search "pricing" --kind user_instruction
python3 -m sessionmcp.cli tool "docker build"       # past commands and API calls
python3 -m sessionmcp.cli tool "stripe" --errors    # only the ones that failed
python3 -m sessionmcp.cli timeline "that migration" # reconstruct how it unfolded
python3 -m sessionmcp.cli synth "rate limiting"     # cross-session material pack
python3 -m sessionmcp.cli evolution "auth design"   # how a decision changed over time

python3 -m sessionmcp.cli code find --capability stripe   # who implemented payment auth
python3 -m sessionmcp.cli code find send_message          # by symbol name
python3 -m sessionmcp.cli code dup                        # duplicate-implementation report

python3 -m sessionmcp.cli creds list                 # variable names only, never values
python3 -m sessionmcp.cli creds get DATABASE_URL     # all candidates, ranked
python3 -m sessionmcp.cli creds get X --masked       # masked form only
python3 -m sessionmcp.cli verify-redaction           # confirm no plaintext in the index

Search is AND. More words means fewer hits. Use the 2–3 words you would actually have typed back then, not a sentence.

The fake-credential problem

Not every "credential" in your history is real. Doc examples, error snippets, values someone made up mid-discussion — all get extracted, and they look exactly like the real thing. A fake in your candidate list is worse than no record at all: it looks perfectly plausible, so you use it.

Blacklist it permanently:

python3 -m sessionmcp.cli creds forget --fingerprint <fp> --reason "doc example"

Deleting alone does nothing — the index re-scans daily and the value comes right back. forget is delete plus blacklist.

The 13 MCP tools

How it works

~/.claude/projects/**/*.jsonl      transcripts Claude Code already writes
            ↓  single pass
   ┌────────┴────────┐
 index side        credential side
 redacted → FTS5   KEY=VALUE → vault.db (0600)
   ↓                  ↓
index.db          vault.db          code.db
full text         credential        symbols +
                  registry          capability tags

CJK search uses bigram pre-tokenization. FTS5's built-in trigram cannot match two-character Chinese words (measured: common two-char terms returned nothing), and unicode61 doesn't segment CJK at all. So CJK text is expanded into adjacent character pairs at write time and the query is expanded the same way — exact matches work, still on the FTS5 index, BM25 ranking preserved.

Configuration

Most of it needs none. To tune, edit sessionmcp/config.py:

Which directories get code-indexed

Auto-derived: working directories with ≥2 sessions in the last 45 days, top 30 by session count. Not hard-coding a list is deliberate — a hard-coded list goes stale silently as projects come and go, and is entirely wrong on a new machine.

If you're new to Claude Code and every project has exactly one session, this derives an empty list and the code index scans nothing. Override:

export SESSION_KNOWLEDGE_PROJECT_DIRS="~/proj-a:~/proj-b"

Claiming a canonical implementation

~/.claude/knowledge/canonical.json lets you declare which file is the canonical implementation of a capability. The generator reads it and never overwrites it, so daily refreshes won't clobber your call. When the same logic shows up a third time, claiming one beats copying it a fourth.

Uninstall

bash uninstall.sh            # remove MCP + hook, keep the index
bash uninstall.sh --purge    # remove the index too

Known limits

• Claude Code transcripts only (~/.claude/projects/**/*.jsonl). Not Cursor, not Copilot.
• Redaction is pattern matching. Common shapes are covered; custom formats can leak. Run verify-redaction periodically.
• Code index reads Python/JS/TS only (.py .js .ts .tsx .mjs .jsx).
• First full index of a few hundred sessions takes 1–3 minutes. Incremental after that is 1–2s.
• Python 3.10+, with FTS5 compiled into the bundled sqlite3. The system Python on macOS sometimes lacks it — install from python.org or brew install python.

中文文档

Contributing and security

See CONTRIBUTING.md before opening an issue or pull request. Never include real transcripts or credentials in public reports. Potential vulnerabilities should be reported privately according to SECURITY.md.

Release history is recorded in CHANGELOG.md.

License

MIT — see LICENSE.