Memento Vault

Persistent knowledge capture for coding agents. Sessions get triaged, scored, and filed as searchable Zettelkasten notes. Runs locally or as a remote service accessible from any device.

Works with Claude Code (native hooks), pi (native extension), and any MCP-compatible agent (Cursor, Windsurf, Codex, etc.) via the built-in MCP server.

What it does

When a coding session ends, the triage pipeline reads the transcript and decides what to keep. Short sessions get a one-liner in a daily log. Substantial ones spawn a background agent that writes atomic notes with YAML frontmatter, wikilinks, and epistemic metadata (how confident is this note? what would make it wrong?). Everything lives in a local git repo you can browse with Obsidian or search with QMD.

For agents without native hook support, the MCP server exposes the same operations as tools: search the vault, store notes, capture sessions, read specific notes.

Install

Homebrew tap

brew tap sandsower/tap
brew install memento-vault
memento-vault install

Git/manual install

git clone https://github.com/sandsower/memento-vault.git
cd memento-vault
./install.sh

Creates the vault at ~/memento, copies hooks and the memento/ package into ~/.claude/, optionally sets up Obsidian views and QMD search. Works on Linux and macOS.

Custom vault path:

MEMENTO_VAULT_PATH=~/my-vault ./install.sh

The installer also links the memento-vault CLI into ~/.local/bin when possible, so future updates can use memento-vault update. If ~/.local/bin is not on your PATH, either add it or run the repository-local ./bin/memento-vault directly.

To safely rerun setup for the same version without discarding local edits:

memento-vault install --reinstall

Check local vault/install health at any time:

memento-vault health        # concise read-only diagnostics
memento-vault doctor        # alias for health
memento-vault health --json # structured output for automation

Warnings exit 0 by default; failures exit 1. Use --strict if automation should fail on warnings too. The command is read-only: it reports suggested repairs such as ./install.sh --reinstall, but does not modify vault/config files.

--force is reserved for recovery from broken installed files. It overwrites memento-managed files and requires confirmation, or MEMENTO_FORCE=1 in non-interactive environments.

Full install (hooks + retrieval + consolidation)

The base install captures knowledge. To also inject knowledge back into active sessions and enable background consolidation:

./install.sh --experimental

This adds two modules:

• Tenet -- three retrieval hooks that inject vault notes into active sessions (briefing, recall, tool context)
• Inception -- background consolidation that clusters notes and synthesizes cross-session patterns

Both require QMD. Inception also needs pip install numpy hdbscan scikit-learn. See Tenet and Inception for details.

MCP install (hookless agents)

For agents that support MCP but not native hooks (Cursor, Windsurf, etc.):

./install.sh --mcp

This installs the memento/ package, writes generic MCP server config, and registers the server with Claude Code and Codex when those CLIs are installed. The server runs over stdio via python -m memento. The installer verifies the mcp Python package is available and installs it if needed. Claude Code gets Claude-specific skills and the concierge agent under ~/.claude; Codex gets agent-agnostic skills under ~/.codex/skills.

You can combine flags: ./install.sh --experimental --mcp gives you hooks + retrieval + MCP.

Pi extension

Memento ships a native pi extension from this repo. The extension is TypeScript, but lifecycle policy stays in Python core: pi calls a short-lived JSON adapter (python3 -m memento.pi_bridge) for briefing, recall, and read-tool context.

For local testing:

pi -e ./extensions/memento.ts

For package installation from a checkout:

pi install /path/to/memento-vault

The pi bridge does not start a long-lived MCP child process. Automatic durable writes are not enabled by default. Candidate captures are queued in local state for review and can be processed into curated notes manually.

Useful pi commands/tools:

• /memento — open the TUI dashboard for status, readable queued-capture review cards, explicit capture selection, processing previews, and live group-level processing progress.
• /memento-status or memento_status — bridge/vault status, lifecycle feature state, queue count.
• /memento-queue or memento_queue — list queued pi capture candidates with deterministic excerpts and size metadata.
• /memento-process or memento_process — process selected queued captures into curated durable notes. With no arguments the command shows a dry-run preview; use /memento for interactive selection and confirmation.
• memento_capture — manually write a durable note; pass queue: true to queue instead.

Pi bridge configuration can live in either ~/.config/memento-vault/pi-bridge.json, project-local .pi/settings.json, or project package.json. The bridge reads memento.piBridge first, then piBridge, then top-level keys:

{
  "memento": {
    "piBridge": {
      "enabled": true,
      "briefing": true,
      "promptRecall": true,
      "toolContext": false,
      "autoCapture": false,
      "captureQueue": true,
      "processQueue": true,
      "processQueueOnSessionClose": false,
      "processQueueMaxCaptures": 3,
      "processQueueModel": null,
      "maxInjectedChars": 4000,
      "maxToolContextPerSession": 5
    }
  }
}

Environment variables override file config:

Variable	Default	Purpose
MEMENTO_PI_ENABLED	true	Enable/disable the extension lifecycle work.
MEMENTO_PI_BRIEFING	true	First-turn project briefing.
MEMENTO_PI_PROMPT_RECALL	true	Prompt recall before each agent turn.
MEMENTO_PI_TOOL_CONTEXT	false	Read-tool context injection.
MEMENTO_PI_MAX_INJECTED_CHARS	4000	Per-injection character cap.
MEMENTO_PI_MAX_TOOL_CONTEXT_PER_SESSION	5	Tool-context injection cap per pi session.
MEMENTO_PI_AUTO_CAPTURE	false	Queue automatic capture candidates on agent_end, compaction, and shutdown lifecycle events.
MEMENTO_PI_CAPTURE_QUEUE	true	Queue automatic capture candidates instead of writing notes directly.
MEMENTO_PI_PROCESS_QUEUE	true	Enable manual queued-capture processing.
MEMENTO_PI_PROCESS_QUEUE_ON_SESSION_CLOSE	false	Reserved future automation route for processing a small batch on session close.
MEMENTO_PI_PROCESS_QUEUE_MAX_CAPTURES	3	Reserved future cap for session-close processing.
MEMENTO_PI_PROCESS_QUEUE_MODEL	unset	Optional model override for processor sessions.

When automatic capture is enabled, pi lifecycle events only create reviewable queue entries in local state (${MEMENTO_PI_STATE_HOME:-${XDG_STATE_HOME:-~/.local/state}/memento/pi}/queue/pi-captures.jsonl). They do not write durable notes until /memento-process or /memento curates the queue into one or more atomic Memento notes. Processing runs write progress under ${MEMENTO_PI_STATE_HOME:-${XDG_STATE_HOME:-~/.local/state}/memento/pi}/processing/<run-id>/, and the /memento footer shows a compact active/failed/interrupted indicator while background processing is visible. Shutdown capture is skipped if another lifecycle capture was already queued during the same session.

Before cutting a pi bridge release, run this interactive smoke checklist from a checkout:

pi -e ./extensions/memento.ts

Then verify /memento-status, /memento-queue, /reload, /new, /resume, /fork, /compact, and quit. The bridge uses short-lived python3 -m memento.pi_bridge calls rather than a persistent child process, so shutdown cleanup should leave no memento-owned child process behind.

Remote vault (access from any device)

Deploy the vault as a remote service so multiple devices and agents share the same knowledge base. The local install is the default; remote mode is opt-in.

Connect to an existing remote vault:

./install.sh --remote https://vault.example.com:8745

This installs hooks that sync to the remote vault over HTTP. A local vault is always created — remote mode is additive, not a replacement.

Deploy the vault yourself — four options depending on your setup:

Option	Cost	What you need
Docker Compose	—	Docker on any machine
Fly.io	~$3-5/mo	Fly.io account
Cloudflare Tunnel	Free	Docker + Cloudflare account with a domain

See Cloud deployment for details.

Upgrading from v1.x

The installer is version-aware. Modified hooks are preserved with .new copies for manual diffing. On subsequent upgrades, modified files are auto-merged via three-way merge (git merge-file).

cd memento-vault && git pull && ./install.sh --experimental

Requirements

• Python 3.9+
• Git
• Claude Code (for hook-based setup)
• QMD (optional, semantic search)
• Obsidian (optional, browsing)
• mcp Python package (for MCP setup, installed automatically by --mcp)

MCP server

The MCP server exposes read, lifecycle, write, and maintenance tools over stdio (local) or HTTP (remote). Any MCP-compatible agent can use them.

Tool	What it does	When to use it
memento_search	Search vault notes (BM25, semantic, RRF fusion, temporal decay, PageRank boost; concrete: auto|true|false for exact identifiers and quoted phrases)	Use before answering questions about past decisions, prior fixes, project history, session context, recurring patterns, or exact identifiers. Do not use it to read a known note path.
memento_get	Read full note content by name or path	Use after memento_search when a returned path needs full content, or directly when the user already supplied an exact note path/name.
memento_briefing / memento_recall / memento_session_context / memento_tool_context	Lifecycle context payloads for session start, prompt recall, one-call budgeted session context, and read-tool context	Host-adapter primitives for automatic injection; not general user-answering tools.
memento_store	Write a single knowledge note with frontmatter and project indexing	Low-level write primitive for sync/automation or agents without skill support; interactive Claude/Codex sessions should prefer /memento or local hooks.
memento_capture	End-of-session triage: parse transcript or accept a summary, write fleeting + atomic note	Low-level SessionEnd equivalent for agents without hook support; not a replacement for interactive /memento workflows.
memento_daily_snapshot	Write a deterministic notes/daily-<date>-<repo-slug>.md snapshot	Low-level structured daily-snapshot primitive for path-controlled integrations; do not use for ordinary notes, interactive memory capture, or session triage.
memento_status	Vault status: note count, project count, config summary	Use for health/config checks; not for recall, project history, or note content.
memento_list	Lightweight note inventory with optional content hashes	Use for sync/inventory clients; not for topical recall or reading notes.
memento_reindex	Rebuild the search index from all markdown files (after bulk adds, git pull, Obsidian sync)	Use after out-of-band file changes or stale-index evidence; not as the default response to a broad/empty search miss.

Common read paths:

• Past decisions: memento_search({"query": "What did we decide about cache invalidation?"}).
• Prior fixes: memento_search({"query": "Where did we fix stale headless Claude MCP config?"}).
• Project history: memento_search({"query": "memento-vault recent triage failures project history"}).
• Exact identifier lookup: memento_search({"query": "MEMENTO_VAULT_PATH", "concrete": "auto"}).
• Reading full content: take a returned path such as notes/cache-policy.md, then call memento_get({"path": "notes/cache-policy.md"}).

Run manually:

python -m memento

For Claude Code, register with the CLI:

claude mcp add memento-vault -s user -e PYTHONPATH="$HOME/.claude/hooks" \
  -- python3 -m memento

For Codex, register with the CLI:

codex mcp add memento-vault \
  --env PYTHONPATH="$HOME/.claude/hooks" \
  -- python3 -m memento

For other MCP-compatible agents (Cursor, Windsurf, etc.), add to your agent's MCP config:

{
  "memento-vault": {
    "command": "python3",
    "args": ["-m", "memento"],
    "env": {"PYTHONPATH": "~/.claude/hooks"}
  }
}

memento_capture is the MCP equivalent of the SessionEnd hook. Agents without hook support can call it at the end of a session with either a transcript path or a structured summary.

Connecting to a remote vault via MCP

If you have a remote vault running (Docker, Fly.io, etc.), any MCP-compatible agent can connect over HTTP. You need two things from whoever deployed the vault:

1. Vault URL (e.g. https://vault.example.com)
2. API key (a bearer token for authentication)

Claude Code — register via the CLI:

claude mcp add -s user --transport http memento-vault https://vault.example.com/mcp \
  --header "Authorization: Bearer <your-api-key>"

Codex — register via the CLI:

export MEMENTO_API_KEY=<your-api-key>
codex mcp add memento-vault \
  --url https://vault.example.com/mcp \
  --bearer-token-env-var MEMENTO_API_KEY

Other MCP agents (Cursor, Windsurf, etc.) — add to your agent's MCP config file:

{
  "memento-vault": {
    "type": "http",
    "url": "https://vault.example.com/mcp",
    "headers": {"Authorization": "Bearer <your-api-key>"}
  }
}

Note: Claude Code ignores ~/.claude/mcp-servers.json. You must use claude mcp add to register servers. Codex uses codex mcp add. The JSON config above is for other MCP clients only.

After connecting, the tools listed above are available. Search returns full note content inline (no extra round-trip needed). Restart your agent session after adding the config.

Tenet

Requires QMD.

Past knowledge flows back into active sessions via three hooks:

• Session briefing (SessionStart): injects your project's recent sessions and relevant vault notes when a session opens. Fast sync output (<50ms), QMD search deferred to background.
• Prompt recall (UserPromptSubmit): searches each prompt against the vault and surfaces matching notes before Claude processes it. Adaptive pipeline: fast BM25 path for confident matches, deep path (PRF, RRF, multi-hop wikilink-following, cross-encoder reranking) for low-confidence queries.
• Tool context (PreToolUse): injects vault notes when Claude reads files in known code areas. Directory-level BM25 with caching and rate limiting.

All three hooks stay silent when they have nothing relevant. Zero tokens injected on trivial prompts, config files, and vendor directories.

Performance

Benchmarked against 30 real sessions (381 prompts, 382 file reads, 16 projects):

Metric	Value
Avg injected per session	~597 chars (~149 input units)
Effective hit rate	100% (when hooks search, they find relevant notes)
Avg recall latency	472ms per prompt (adaptive pipeline)
Avg tool-context latency	230ms per file read
Session briefing	<282ms (deferred QMD search is non-blocking)
LongMemEval NDCG@10	0.892 (retrieval quality, 500 questions)

Full analysis in docs/performance-analysis.md.

Inception

Requires QMD and pip install numpy hdbscan scikit-learn.

Inception clusters your vault notes by embedding similarity and synthesizes pattern notes -- higher-order insights that span multiple sessions. It runs as a detached background process after triage, or on demand via /inception.

Session ends -> triage completes -> inception check
  -> enough new notes? spawn background process
  -> HDBSCAN clusters ALL notes (not just new ones)
  -> only synthesizes clusters with new notes or refresh candidates
  -> writes pattern notes with source: inception
  -> backlinks source notes, commits, reindexes QMD

Opt-in via config:

inception_enabled: true
inception_backend: codex    # "codex" (subscription, $0) or "claude" (API, ~$1/month)
inception_threshold: 5      # new notes before triggering
inception_max_clusters: 10  # max patterns per run

Pattern notes start at certainty 3 (subject to temporal decay and defrag). Use /inception --dry-run to preview clusters before writing. Full architecture and limitations in docs/how-it-works.md.

What you get

~/memento/
  fleeting/       Daily logs, one line per session
  notes/          Atomic permanent notes (the good stuff)
  projects/       Project indexes linking notes and sessions
  archive/        Stale notes moved here by /memento-defrag

Skills

Command	What it does
/memento	Capture insights mid-session
/inception	Find cross-session patterns, synthesize pattern notes (experimental)
/memento-defrag	Archive low-value notes, keep the vault focused
/start-fresh	Capture + save pending work + clear context
/continue-work	Recover context from local state and vault

Agent-specific packaging:

• Claude Code skills live in skills/ and are installed to ~/.claude/skills.
• Claude Code agents live in agents/ and are installed to ~/.claude/agents.
• Agent-agnostic skills live in skills/generic/ and are installed to ~/.codex/skills when Codex is available. These are also the source to adapt for future Gemini, Kimi, or other MCP-capable agents.

How triage works

Session ends -> triage hook fires (or memento_capture MCP tool)
  -> always: write fleeting one-liner (no LLM cost)
  -> if substantial: spawn background agent for atomic notes
  -> delta-check: skip if vault already covers the topic
  -> auto-commit + QMD reindex

"Substantial" means 15+ exchanges, 3+ files edited, or touching notable files (plans, designs, CLAUDE.md). All thresholds are configurable.

Note format

Each note has YAML frontmatter: certainty score (1-5), optional validity context, type (decision/discovery/pattern/bugfix/tool), wikilinks to related notes. Full schema in docs/frontmatter-schema.md.

Cloud deployment

Deploy the vault as a service accessible from multiple devices, agents, or the claude.ai/code web interface.

Docker Compose

The simplest option. Run on any machine with Docker — a home server, VPS, or your laptop.

MEMENTO_API_KEY=$(python3 -c "import secrets; print(secrets.token_urlsafe(32))") \
  docker compose up -d

Vault is at http://localhost:8745/mcp. For TLS on a VPS, add Caddy or use setup-remote.sh --host your-domain.com --tls.

Fly.io

Managed cloud with persistent volumes, automatic TLS, ~$3-5/mo.

fly launch --copy-config --no-deploy
fly volumes create vault_data --region iad --size 1 --yes
fly secrets set MEMENTO_API_KEY=$(python3 -c "import secrets; print(secrets.token_urlsafe(32))")
fly deploy

Vault is at https://<app-name>.fly.dev/mcp. The included fly.toml is pre-configured.

Cloudflare Tunnel

Expose a local Docker container to the internet via Cloudflare. No public IP needed, automatic TLS, free.

1. Create a tunnel in Cloudflare Zero Trust → Networks → Tunnels
2. Set the tunnel's public hostname to point at http://vault:8745
3. Run:

export CLOUDFLARE_TUNNEL_TOKEN=<your-token>
export MEMENTO_API_KEY=$(python3 -c "import secrets; print(secrets.token_urlsafe(32))")
docker compose -f docker-compose.cloudflare.yml up -d

Connecting clients

Once the vault is running, connect any device:

MEMENTO_API_KEY=<key> ./install.sh --remote https://vault.example.com --experimental

The installer registers the remote MCP server with Claude Code and Codex when their CLIs are installed. Codex stores only the bearer-token environment variable name, so start Codex with MEMENTO_API_KEY available in the environment.

To upgrade an existing Claude-only remote install after installing Codex, rerun:

./install.sh --remote --experimental

If ~/.claude/memento-remote.env exists, the installer reuses the saved remote URL and API key.

Or configure MCP directly:

# Claude Code
claude mcp add -s user --transport http memento-vault https://vault.example.com/mcp \
  --header "Authorization: Bearer <your-api-key>"

# Codex
export MEMENTO_API_KEY=<your-api-key>
codex mcp add memento-vault \
  --url https://vault.example.com/mcp \
  --bearer-token-env-var MEMENTO_API_KEY

For other MCP clients (Cursor, Windsurf, etc.), add to their MCP config:

{
  "memento-vault": {
    "type": "http",
    "url": "https://vault.example.com/mcp",
    "headers": {"Authorization": "Bearer <your-api-key>"}
  }
}

Architecture

The memento/ package is agent-agnostic. Seven modules handle config, search, graph algorithms, vault I/O, LLM abstraction, and type definitions. Hooks and MCP tools are thin wrappers around this package.

memento/
  config.py          Configuration, project detection, vault identity
  search.py          Search pipeline: PRF, RRF, temporal decay, PageRank
  search_backend.py  Abstract search backend (QMD, Embedded, Grep — auto-detected)
  embedded_search.py Built-in search: SQLite FTS5 + sqlite-vec vectors, RRF hybrid
  embedding.py       Embedding providers: local nomic-embed-text, Voyage, OpenAI, Google
  indexer.py         Background indexer for files added outside the write path
  graph.py           Wikilink graph, PageRank, PPR expansion
  store.py           Vault I/O, write locking, dedup, note writing
  llm.py             5 backends: claude, codex, gemini, anthropic-api, openai-compat
  auth.py            Pluggable auth (bearer token, extensible to per-user)
  remote_client.py   HTTP client for hooks talking to a remote vault
  utils.py           Secret sanitization, tag normalization
  types.py           TypedDict definitions (SearchResult, NoteMetadata, SessionMeta)
  adapters/          Transcript parsing (Claude adapter, pluggable for others)
  mcp_server.py      MCP server (read/lifecycle/write/maintenance tools, stdio + HTTP transport)

LLM backend is configurable:

llm_backend: claude        # claude, codex, gemini, anthropic-api, openai-compat
llm_model: sonnet          # model name for the chosen backend

Configuration

Config lives at ~/.config/memento-vault/memento.yml. All options in docs/configuration.md.

vault_path: ~/memento
exchange_threshold: 15
file_count_threshold: 3
qmd_collection: memento
auto_commit: true

# Tenet retrieval hooks
session_briefing: true
prompt_recall: true
tool_context: true

# Retrieval pipeline
prf_enabled: true            # pseudo-relevance feedback query expansion
rrf_enabled: true            # reciprocal rank fusion (BM25 + vsearch)
ppr_enabled: true            # personalized pagerank link expansion
reranker_enabled: true       # cross-encoder reranking (local ONNX)
multi_hop_enabled: false     # follow wikilinks from top results

Extension points

Three ways to layer project-specific behavior on top without forking:

• project_rules in config: map directories to project slugs and ticket patterns
• extra_qmd_collections in config: search additional QMD collections alongside the vault
• ~/.claude/skills/memento-post/SKILL.md: post-capture hook that runs after /memento creates notes (e.g., promote to a team vault, apply domain tags)

Search backends

The vault auto-detects the best available search backend:

1. QMD (if installed) — BM25 + vector search + reranking via external CLI tool (3.2GB)
2. Embedded (if onnxruntime + sqlite-vec installed) — built-in FTS5 + sqlite-vec with nomic-embed-text, RRF hybrid fusion. No external tools needed. Default on remote/Docker deployments.
3. Grep — substring matching fallback. Always works, no dependencies.

Override with search_backend: qmd | embedded | grep in config, or MEMENTO_SEARCH_BACKEND env var.

The embedded backend uses a single search.db SQLite file (derived, disposable). Markdown files stay the source of truth. Embeddings come from a local nomic-embed-text-v1.5 model by default (137MB, no API key). Optional API providers (Voyage, OpenAI, Google) configurable via embedding_provider in config.

QMD (optional)

QMD adds semantic search over your vault. Without it the concierge agent uses the embedded backend or falls back to grep. QMD is required for Tenet and Inception.

qmd search "caching strategy" -c memento

The concierge agent uses QMD automatically when you ask about past decisions.

Model warmup

Tenet's deferred briefing search uses vector search, which requires loading an embedding model. First call after a reboot takes 6-8s; subsequent calls are ~1.5s (model stays in OS page cache). The installer can add a background warmup to your shell rc file so the model is always cached:

# Added to .zshrc/.bashrc by the installer (optional)
[ -x /path/to/memento-vault/bin/memento-vault ] && /path/to/memento-vault/bin/memento-vault warmup >/dev/null 2>&1

You can also run it manually:

memento-vault warmup

Obsidian (optional)

The installer copies Obsidian config and Base views into the vault. Open ~/memento as a vault and you get:

• Graph view showing how notes connect
• Base views: by type, by project, recent, decisions, bugfixes
• Daily notes pointed at fleeting/
• Wikilink navigation between notes

Uninstall

cd memento-vault
./uninstall.sh

Removes hooks, skills, and the agent from ~/.claude/. Your vault and notes stay untouched.

How it works

Full flow diagram in docs/how-it-works.md.

License

MIT