memex

Local-first second brain for Claude. Saves notes as Markdown and recalls them across sessions with offline semantic search, no cloud and no API keys.

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Documentation

memex

Make Claude smarter about you.

npm install -g @evan-moon/memex

Make Claude smarter about you.

Local-first second brain that connects to Claude via MCP. Notes are stored as plain Markdown and indexed with a local ML model, fully offline, no API keys, nothing leaves your machine.

The problem

Claude is only as smart as what's in the conversation. Your decisions, your context, your thinking, invisible unless you paste them in every time.

You:    What did we decide about the auth approach last sprint?
Claude: I don't have context from previous conversations...

The fix

You:    What did we decide about the auth approach last sprint?

Claude: [memex · search_notes · "auth approach decision"]

        Found 2 notes:

        Auth Architecture Decision  Apr 14  #auth #backend
        ─────────────────────────────────────────────────────
        Chose JWT + refresh tokens over sessions. Rationale:
        stateless design fits horizontal scaling plan.

        Based on your April 14th note: you went with JWT +
        refresh tokens. Tom also flagged keeping auth decoupled
        from payment logic, separate bounded contexts.

Claude searches your notes before answering and saves insights at the end of every conversation, automatically, without being asked.

Install

npm install -g @evan-moon/memex

Connect to Claude Code:

memex mcp install

That's it. On first run, the embedding model (~450MB) downloads once to ~/.memex/models/.

Auto-recall (optional)

memex recall install

Turns retrieval from something Claude has to decide to do into something that just happens. Every prompt you type is semantically searched against your notes, and the top 3 titles are injected as context before Claude answers — the same way native memory works. Claude then pulls full notes with get_note when a title looks relevant.

A background daemon keeps the embedding model warm (~/.memex/recall.sock), so a lookup costs ~30ms instead of the ~1.5s a cold CLI search spends loading the model. It idles out after 2 hours.

Cost: ~200MB resident while warm, plus up to 3 note titles of context per prompt. Remove with memex recall uninstall.

Features

Semantic search, finds notes by meaning, not just keywords. Multilingual (Korean + English), runs fully offline via multilingual-e5-base
Hybrid retrieval, vector search + BM25 full-text + tag matching, fused via Reciprocal Rank Fusion
Date filter, narrow search to a time range with --from / --to
Note layers, every note is past (immutable record), state (mutable plan), or rule (Claude behaviour guide). Past notes refuse updates; rule notes auto-inject into Claude's system prompt
Flashback, save and search automatically surface older notes from a different folder that are semantically related, "you wrote about this 124 days ago in a different context"
Inference engine, deterministic signals surface un-synthesized patterns (cross-year arcs, stale state notes, tag revivals); you promote good ones into inferences (hypotheses with provenance) that auto-invalidate when their source notes change. No LLM in the core
MCP server, Claude searches and saves automatically. No extra CLAUDE.md setup needed
Auto-recall, opt-in hook that searches your notes on every prompt and injects the hits before Claude answers, so recall never depends on Claude remembering to look
Duplicate detection, save_note warns when a semantically similar note already exists, nudging Claude to update rather than create
Backlinks, link notes with [[Title]] syntax; get_note shows which notes reference it
Digest, memex digest summarises notes saved in the last N days, grouped by folder
CLI, add, search, tag, browse, and index notes from the terminal
Obsidian-compatible, notes saved as .md files; works alongside existing vaults
Local DB, SQLite + sqlite-vec at ~/.memex/memex.db

CLI

# Add notes
memex add                                    # interactive prompt (asks for layer)
memex add --title "Note title" --content "..." --layer past
memex add --title "Note title" --file ./note.md --layer state
memex add --title "Note title" --content "..." --folder conversations/tom --layer past
memex add --title "Note title" --content "..." -T typescript -T architecture --layer past

# Layers
memex layer                               # distribution of past / state / rule
memex layer <id> state                     # move a note to a different layer

# Search
memex search "semantic search query"         # multilingual
memex search "knowledge management" --limit 10    # multilingual: matches Korean/Japanese notes too
memex search "query" --tag typescript        # filter by tag
memex search "query" --from 2026-04-01       # notes since a date
memex search "query" --from 2026-04-01 --to 2026-04-30

# Browse
memex list                                   # recent 10 notes
memex list --limit 20
memex show <id>
memex tags                                   # all tags with counts
memex related <id>                           # semantically related notes
memex digest                                 # last 7 days + signals + inferences
memex digest --days 30                       # summary of last 30 days

# Insights (inference engine)
memex signals                                # detect un-synthesized patterns
memex signals --type hidden_arc              # one type only
memex signals dismiss <id>                   # triage (also: snooze)
memex signals mint <signalId>                        # print evidence bundle to synthesize
memex signals mint <signalId> --title "..." --summary "..." --confidence 0.7
memex inferences                             # list inferences (auto-flags stale)
memex schedule                               # print cron/launchd snippet (no daemon)

# Edit / delete
memex edit <id>
memex delete <id>
memex delete --yes <id>                      # skip confirmation

# Index external directories
memex source add ~/Documents/My\ Notes       # register a vault
memex source list
memex source remove ~/Documents/My\ Notes
memex index                                  # scan vault + all sources
memex index --force                          # re-index everything
memex reembed                                # re-embed with current model

# Config
memex config show
memex config set vault-path ~/Documents/Second\ Brain

# MCP
memex mcp install                            # register with Claude Code

# Auto-recall
memex recall install                         # search notes on every prompt, inject hits
memex recall uninstall                       # remove the hook
memex mcp path                               # print MCP binary path

MCP server

Claude Code

memex mcp install

Or manually:

claude mcp add memex -- node "$(memex mcp path)"

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "memex": {
      "command": "node",
      "args": ["<path from `memex mcp path`>"]
    }
  }
}

Available tools

Tool	Description
`save_note`	Save a note, requires `layer`, warns if a similar note already exists, surfaces flashbacks
`search_notes`	Semantic search; supports `category`, `tag`, `date_from`, `date_to` filters; appends flashbacks for the top result
`list_notes`	List recent notes
`list_tags`	List all tags with note counts
`list_folders`	List all folders with note counts
`get_note`	Get full content and backlinks of a note by ID
`update_note`	Update title or content. Refuses `past` notes (with `[Amendment]` suggestion) and `rule` notes (user-only)
`delete_note`	Delete a note by ID
`get_signals`	Deterministic un-synthesized patterns (hidden_arc / stale_state / dangling_link / tag_burst)
`update_signal_status`	Triage a signal, dismiss or snooze
`list_inferences`	List synthesized hypotheses (re-checks staleness first)
`get_inference`	One inference with full provenance + change/delete markers
`mint_inference`	Persist an approved hypothesis, requires explicit confirmation

Inferences are kept separate from notes (excluded from search) and are cited as hypotheses, never facts. Detection stays deterministic; the only LLM step is synthesizing an inference's summary, which Claude does, never memex.

Note layers

Every note is classified into one of three layers based on mutability:

Layer	Meaning	Claude's permission
`past`	Record of what happened, retros, meetings, decision rationale, debugging sessions	Append-only. `update_note` refuses, suggesting an `[Amendment]` note instead
`state`	Current state or plans, project progress, roadmaps, a person's current role	Freely updatable
`rule`	Behaviour guide for Claude, coding style, search policy	Claude is read-only. Only the user writes

The CLI prints a colour-coded [past] / [state] / [rule] badge next to each note in list, search, and show.

save_note (MCP) and memex add (CLI) require an explicit layer. The classification rules are documented in the tool description so Claude picks correctly.
On first run, existing notes get a folder-based backfill: projects/dev/herald → state, coding → rule, everything else → past. Migration is idempotent.
rule notes are also auto-injected into the MCP server's instructions, see Rule layer auto-inject below.

Flashback

When you save a note or search, memex automatically surfaces older notes from a different folder that are semantically similar, "you wrote about this 124 days ago in a different context." Stored as system-generated backlinks (note_links.source = 'flashback'), separate from your [[wikilinks]] (source = 'wiki').

Tune via env:

Env	Default	Behaviour
`MEMEX_FLASHBACK_DAYS`	`90`	minimum age gap, in days
`MEMEX_FLASHBACK_DIST`	`0.4`	maximum vector distance (lower = stricter match)
`MEMEX_FLASHBACK_LIMIT`	`3`	max suggestions per surface

Rule layer auto-inject

Notes with layer = 'rule' are appended to the MCP server's instructions on boot, under a ## House Rules section. Claude sees them at the start of every conversation, no search_notes call required. This is the right home for coding style guides or other behavioural guidance.

Env	Default	Behaviour
`MEMEX_INJECT_RULES`	enabled	Set to `0` to disable injection entirely
`MEMEX_RULES_MAX_CHARS`	`8000`	Byte budget for the injected section; overflow is truncated with a `console.warn`

Updates to rule notes are picked up on the next Claude Desktop / Claude Code restart.

Configuration

Config lives at ~/.memex/config.json.

Key	Default	Description
`vault_path`	`~/Documents/Second Brain`	Directory where `.md` files are saved
`sources`	`[]`	Additional directories to index (e.g. existing Obsidian vaults)
`aliases`	`{}`	Search alias map, e.g. `{ "js": ["javascript", "ecmascript"] }`, values can be any language to bridge across scripts

memex config set vault-path ~/my-vault

Architecture

~/.memex/
  config.json, vault path, sources, and aliases
  memex.db, SQLite DB (notes + vec embeddings + FTS5 index)
  models/, cached embedding model

<vault>/
  *.md, notes (Obsidian-compatible)

Package	Role
`@memex/db`	SQLite schema, drizzle queries, sqlite-vec + FTS5 integration
`@memex/embed`	Local embedder via @huggingface/transformers
`@memex/utils`	Config, path helpers, shared utilities
`@memex/mcp`	MCP server (bundled into CLI dist)

The ecosystem

memex is one of three local-first tools that share one principle, your data stays on your machine, and the AI comes to it. They interoperate through any MCP client, and none depends on the others.

flowchart TB
    U([You])
    subgraph I["Interfaces, talk to your tools"]
        direction LR
        CD[Claude Desktop]
        CC[Claude Code]
        H["Herald · voice"]
    end
    subgraph T["Local-first tools, each owns its data, on your machine"]
        direction LR
        F["firma · money<br/>~/.firma"]
        M["memex · memory<br/>~/.memex"]
        S["skope · news<br/>~/.skope"]
    end
    U --> I
    I -- MCP --> F & M & S
    F <-. never call each other .-> M
    M <-.-> S

firma · money, portfolio, net worth, cash flow
memex · memory, notes and the context behind them, across sessions
skope · news, a personalized lens on the world

You reach them through Claude Desktop, Claude Code, Cursor, or Herald, a voice interface. The tools compose through the model, never by calling each other.

llms.txt

llms.txt is a machine-readable summary of this project for LLM agents, concise description with documentation links, following the llms.txt standard.

License

MIT