Archivist MCP

Local-first project memory server for agents and developers

Features • Quick Start • MCP Setup • WebUI • Usage • Tools • Configuration • Reliability • Troubleshooting

Archivist MCP is a memory layer for coding agents. You run it alongside your project, connect your MCP client, and the agent can persist/retrieve decisions, incidents, rules, and architecture context across sessions. WebUI is for human review and controlled write actions when you want visibility before changing memory.

Features

• Three-tier memory model: working memory, compact core memory (core_memory.md/.json), archival graph

• Graph + lifecycle safety: typed nodes/edges, state transitions, optimistic concurrency, immutable audit events

• Hybrid retrieval: FTS + local embeddings + graph degree + recency with provenance and confidence

• MCP transports: JSON-RPC over STDIO and HTTP (/mcp)

• Team mode: SSE transport with bearer-token auth, role matrix, and project scoping

• Controlled write workflows: conflict resolution, branch-to-project promotion, stale-memory invalidation

• Security hardening: payload allowlists, size/type validation, sanitization, redaction, retention purge

• Reliability tooling: integrity checks, snapshots, restore, startup recovery, rebuild index+embeddings

Quick Start

Prerequisites

• Python 3.11+

• macOS/Linux/Windows

1) Initialize database

python3 scripts/migrate.py --db .archivist/archivist.db

2) Start STDIO server

python3 -m archivist_mcp.stdio_server --db .archivist/archivist.db

3) Seed a project/user (first-time)

python3 - <<'PY'
from archivist_mcp.db import connect
conn = connect('.archivist/archivist.db')
conn.execute("INSERT OR IGNORE INTO projects(project_id,name) VALUES('proj-1','Project One')")
conn.execute("INSERT OR IGNORE INTO users(user_id,display_name) VALUES('user-1','User One')")
conn.commit()
conn.close()
PY

MCP Setup

Option A: VS Code / Codex Extension (STDIO MCP server)

In MCP settings (Add MCP Server) use:

• Name: archivist-mcp

• Command to launch: python3

• Arguments: -m archivist_mcp.mcp_stdio_server --db .archivist/archivist.db

• Working directory: your repo root (example: /path/to/your/repo)

• Env vars: optional (ARCHIVIST_CONFIG_PATH, etc.)

If you need strict team-style user enforcement in stdio mode, add --require-user-id.

Option B: MCP over HTTP bridge

If your MCP client expects stdio process launch but you want the HTTP server, launch a bridge command such as:

npx -y mcp-remote http://127.0.0.1:8766/mcp

WebUI

Start directly:

python3 -m archivist_mcp.mcp_http_server --db .archivist/archivist.db --host 127.0.0.1 --port 8766
python3 -m archivist_mcp.sse_server --db .archivist/archivist.db --host 127.0.0.1 --port 8765
python3 -m archivist_mcp.webui_server --db .archivist/archivist.db --host 127.0.0.1 --port 8090

Open:

• http://127.0.0.1:8090

Views:

• Search (with explain-why provenance)

• Graph

• Decision timeline

• Incident timeline

• Conflict inbox

• Controls (rule writes, conflict resolve, scope promotion, memory invalidation)

Usage

What this project is for

Use case:

1. You work with an agent on a codebase over many sessions.

2. Important context normally gets lost between sessions.

3. Archivist stores that context in a local graph and makes it available through MCP tools.

4. The agent can then recall prior decisions/conflicts/incidents instead of re-discovering them.

How tool discovery and invocation works

1. After MCP connection, the client initializes the server and requests available tools (tools/list).

2. The client chooses a tool based on your prompt and invokes it (tools/call) with arguments.

3. You usually do not call MCP tools manually; your agent does it for you.

4. If your client has a tools panel, you can verify connection by checking the listed Archivist tools.

When to use which tool family

• Capture memory: create_entity, archive_decision, store_observation, create_edge

• Recall context: search_graph, read_node, get_project_summary, list_recent_incidents

• Maintain memory quality: update_entity, deprecate_node, resolve_conflict, invalidate_stale_memory

• Codebase-derived memory: extract_symbols, rebuild_index_and_embeddings

• Ops/compliance: export_audit_log, purge_observations, get_metrics

Typical day-to-day flow

1. Agent reads context with search_graph.

2. During work, agent writes new facts/decisions.

3. If stale data appears, agent or human resolves/deprecates it.

4. You review timelines/conflicts in WebUI when needed.

What gets persisted

• Nodes: decisions, incidents, rules, entities, observations

• Edges: relationships like dependencies, resolution links, deprecations

• Audit/conflict records

• Compact core summary files: core_memory.md and core_memory.json

MCP Tools

Current tool set (subject to feature flags):

• health

• version

• get_capabilities

• get_metrics

• create_entity

• read_node

• update_entity

• create_edge

• search_graph

• store_observation

• archive_decision

• get_project_summary

• list_recent_incidents

• deprecate_node

• compact_core_memory

• extract_symbols

• rebuild_embeddings

• rebuild_index_and_embeddings

• export_audit_log

• purge_observations

• resolve_conflict

• promote_branch_record

• invalidate_stale_memory

search_graph note:

• include_deprecated=false returns active records only.

• include_deprecated=true allows deprecated/invalidated/superseded records (archived excluded).

Configuration

Config source order:

1. .archivist/config.toml (or ARCHIVIST_CONFIG_PATH)

2. environment variable overrides

Common env vars:

• ARCHIVIST_CONFIG_PATH

• ARCHIVIST_DISABLE_EMBEDDINGS=true|false

• ARCHIVIST_CORE_MAX_KB

• ARCHIVIST_RATE_LIMIT_PER_MINUTE

• ARCHIVIST_STRUCTURED_LOGGING=false

• ARCHIVIST_DB_ENCRYPTION_KEY

• ARCHIVIST_ENCRYPTION_REQUIRED=true

• ARCHIVIST_SSE_TOKENS (JSON token map for team auth)

• ARCHIVIST_TLS_ENABLED=true

• ARCHIVIST_TLS_CERT_FILE, ARCHIVIST_TLS_KEY_FILE

Example team token map:

{
  "token-a": {
    "user_id": "user-1",
    "role": "writer",
    "projects": ["proj-1"]
  },
  "token-b": {
    "user_id": "maint-1",
    "role": "maintainer",
    "projects": ["proj-1"]
  }
}

Encryption behavior:

• If ARCHIVIST_DB_ENCRYPTION_KEY is set and SQLCipher is unavailable, startup fails.

• ARCHIVIST_ENCRYPTION_REQUIRED=true also enforces fail-closed encryption checks.

Reliability & Ops

Integrity check

python3 scripts/check_integrity.py --db .archivist/archivist.db

Snapshot and restore

python3 scripts/create_snapshot.py --db .archivist/archivist.db --snapshot-dir .archivist/snapshots
python3 scripts/restore_snapshot.py --snapshot .archivist/snapshots/<snapshot>.db --db .archivist/archivist.db

Rebuild derived state

python3 scripts/rebuild_index_and_embeddings.py --db .archivist/archivist.db --project-id proj-1 --root .

Project Structure

archivist_mcp/
  mcp_stdio_server.py      # MCP JSON-RPC over stdio
  mcp_http_server.py       # MCP JSON-RPC over HTTP (/mcp)
  sse_server.py            # Team mode HTTP+SSE
  webui_server.py          # Browser UI + controlled write APIs
  tooling/server.py        # Tool router, validation, envelope/errors
  storage/repository.py    # Graph persistence + lifecycle + audit
  retrieval/               # embeddings + hybrid retrieval
  indexing/                # symbol extraction + incremental indexer
  memory/materializer.py   # core_memory.md + core_memory.json
  migrations/sql/          # schema migrations
scripts/
  migrate.py
  create_snapshot.py
  restore_snapshot.py
  check_integrity.py
  rebuild_index_and_embeddings.py
tests/
  test suites for integration, retrieval, security, team mode, and WebUI behavior
docs/
  quickstart.md
  troubleshooting.md
  recovery_runbook.md

Troubleshooting

AUTHZ_DENIED

Token role/scope does not permit the tool or project. Check ARCHIVIST_SSE_TOKENS role and projects.

CONFLICT_ERROR

Optimistic version mismatch. Re-read node, use latest version, retry or resolve via conflict workflow.

EMBEDDING_DISABLED

Embeddings are disabled/unavailable. Retrieval falls back to fts_graph mode.

Blank WebUI timelines

The UI reads from the DB passed to webui_server --db. Ensure your seeding and servers all point at the same DB path.

Documentation

• Quickstart: docs/quickstart.md

• Troubleshooting: docs/troubleshooting.md

• Upgrade/Migration: docs/upgrade_migration.md

• Recovery runbook: docs/recovery_runbook.md

• Security threat model: docs/security_threat_model.md

Built for durable project memory across agent sessions, with local-first defaults and auditable writes.