mom

Memory Oriented Machine — she remembers, so you don't have to.

Install • Quick start • How it works • Typical workflow • Harness support

Mom gives AI coding agents persistent memory across sessions, projects, and tools.

Instead of re-explaining architecture, decisions, conventions, and constraints every time you start a new chat, mom records them to an append-only Ledger and projects them into a per-project markdown vault your agent reads with its normal file tools.

[!IMPORTANT] v0.50.0-alpha is the current public alpha. It replaces the SQLite vault and MCP server with a per-project markdown vault projected from an append-only Ledger (see ADR 0024). Pi, Claude Code, and Codex flows are validated end-to-end. Upgrading from an older install? See Upgrade.

Why mom?

AI agents are useful, but they forget.

Mom is the memory layer beside them:

• Persistent — memory survives /clear, compaction, restarts, and tool switches.
• Local-first — captured turns live in an append-only Ledger at $HOME/.mom/ledger/; the projected vault lives per-project under .mom/vault/.
• Plain markdown — memory is .md files you can open, read, and diff. The agent reads them with its normal file tools; there is no query server.
• Harness-agnostic — Pi, Claude Code, and Codex are integration targets, not storage silos.
• Agent-integrated — memory is delivered through the harness context file and mom skills.
• Continuously recorded — supported harness transcripts are watched and folded into the vault.

Install

Homebrew

brew install momhq/tap/mom

To upgrade:

brew update && brew upgrade mom && mom version

From source

git clone https://github.com/momhq/mom.git
cd mom
make install

Quick start

Initialize mom once:

mom init

Mom will set up its central store at ~/.mom (config + Ledger), configure detected harness integrations, install mom skills where supported, ask whether to start capturing the current directory, and start the watch daemon.

Then open your agent and work normally. Mom records sessions in the background and folds them into the vault. At the start of each session your agent reads .mom/vault/ on its own, so it already knows your project's history — just ask. The skills you'll actually run:

/mom-fold     # save recent sessions into the vault (e.g. when wrapping up)
/mom-status   # check that mom is capturing, and what it knows

How it works

The write path is a straight line; agents read the projected markdown directly.

AI harnesses (Pi · Claude Code · Codex)
        │  transcripts
        ▼
mom watcher → Editor → Ledger          ($HOME/.mom/ledger/, append-only)
        │
        │  mom vault fold  (/mom-fold, or the daemon timer)
        ▼
services/projection  (Reader → Synthesizer → Writer)
        │
        ▼
.mom/vault/*.md   ← the agent reads these with its file tools
  ├─ INDEX.md           # router: "read X when the task looks like Y"
  ├─ topics/<slug>.md   # decisions, patterns, preferences by subject
  ├─ timeline/<YYYY-MM>.md
  └─ summaries/overview.md

Lose the vault and mom vault rebuild regenerates it from the Ledger; the Ledger is the durable backbone and is never derived.

Typical workflow

After installing mom, open your agent and work normally.

Mom watches supported transcript sources in the background and records them to its Ledger. After a long session, or whenever you want to preserve recent context, ask your agent to run:

/mom-fold

The skill folds newly captured sessions into a navigable markdown vault under .mom/vault/.

There is no recall command to run. At the start of each session your agent reads .mom/vault/INDEX.md and follows it to the relevant memory, so it answers from what mom already knows — decisions, conventions, and context — without you re-explaining them. Just work normally.

To check that mom is connected:

/mom-status

Explore with Lens

For a visual view of captured sessions and privacy-projected tool activity, run:

mom lens

Lens is local (loopback only) and reads the append-only Ledger.

Harness support

[!NOTE] Mom uses harness to mean the agent framework around the model: tools, hooks, transcripts, and prompt/context files.

Upgrade from older mom installs

If you already have an older mom install:

mom upgrade --dry-run
mom upgrade

Upgrade regenerates the harness context blocks, tears down the retired MCP registration, removes obsolete hook commands and deprecated skills, and installs or updates the current skills as a soft-fail step.

[!IMPORTANT] v0.50 does not migrate a pre-v0.50 SQLite vault ($HOME/.mom/mom.db). The new vault rebuilds from go-forward capture in the Ledger. mom upgrade detects a leftover mom.db and prints the command to remove it once capture is confirmed.

Data and privacy

Mom is local-first.

• The append-only Ledger lives at $HOME/.mom/ledger/; the projected vault lives per-project under .mom/vault/.
• MOM_VAULT=/path/to/dir overrides the central $HOME/.mom location for tests or isolated runs.
• Capture is privacy-gated: a turn is only recorded when the directory is bound to a project (.mom-project.yaml).
• Lens uses privacy-projected metadata.
• Raw tool arguments, raw user text, shell command arguments, query strings, paths, and flags are not stored as operational log detail.
• Explicit record flows reject invented session IDs; harness session IDs must come from the harness.

Troubleshooting

Check installation

mom version
mom status
mom doctor

Watcher is not seeing new sessions

mom watch --status
mom watch --sweep

Mom canonicalizes project paths, including macOS /tmp and /private/tmp, so watcher state should not split across symlinked aliases.

Skills are missing

Run init or upgrade again:

mom init
# or
mom upgrade

Skills install is a soft-fail step, so mom can be usable even if the external skills installer is temporarily unavailable.

Project layout

The codebase is organised into role-based top-level buckets (see ADR 0017).

.
├── cmd/mom/                # entrypoint
├── ingress/                # external input: CLI, watcher adapters, harness detection
├── events/                 # canonical event Editor, schema Registry, envelope
├── services/               # projection (the fold) and lens (dashboard)
├── storage/                # durable state — ledger (append-only), librarian (path resolver)
├── ops/                    # background lifecycle — daemon, diagnose
├── shared/                 # cross-cutting utilities — config, pathutil, scope, project, ux, archtest
├── adr/                    # architecture decisions
├── prd/                    # product requirements
├── skills/                 # _mom_ slash skills
├── assets/                 # logo and brand assets
├── Formula/mom.rb          # Homebrew formula
└── .github/workflows/      # CI and release automation

Resources

• Latest release
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• Homebrew tap
• Privacy policy