Claude Checkpoint MCP README

claude-checkpoint-mcp

Save your Claude Code session state locally, so a crash, /clear, or context limit doesn't make Claude rebuild context from scratch.

claude-checkpoint-mcp is a local Model Context Protocol server with two tools:

save_session_checkpoint writes your session's working state to a small JSON file in the project.
load_session_checkpoint turns that file back into a compact resume brief.

It runs entirely on your machine. Nothing is sent anywhere.

Why: stop paying twice for the same context
How it works
Installation
Configuration
Usage
Tool reference & examples
The .claude-checkpoint file
Security & privacy
Troubleshooting
Development

Why: stop paying twice for the same context

A long Claude Code session builds up a lot of context:

what you're trying to do;
which approaches already failed;
which files matter;
which test is still red.

Several things can wipe that out mid-task:

a terminal crash, SSH drop, or laptop sleep;
running out of context window;
a /clear to get a fresh window.

The next session starts cold. To get back to where you were, Claude has to rebuild that context:

Re-reading files to work out what was changed and why. Every file read is input tokens.
Re-running exploration: grep, git diff, ls, test runs, all just to rediscover state.
Re-explaining. You retype the goal, the constraints, and the dead ends, or Claude rediscovers the dead ends the hard way.

Each of those turns resends the growing conversation as input, so the cost compounds.

claude-checkpoint-mcp swaps that rebuild for one small, structured read:

	Without a checkpoint	With `load_session_checkpoint`
Restoring the goal & constraints	You retype them, or Claude infers them	One section of the brief
Knowing what's done vs. pending	Re-derived from code and git	Task list with statuses
Knowing which files matter	Broad re-reading	Exact list of touched files, with notes
Knowing what changed since	Re-read everything to be safe	Only files whose content actually changed are flagged
Remembering failed attempts	Often repeated	Recorded under Decisions & gotchas

The resume brief for a typical session is about 1.2 KB of markdown, a few hundred tokens. The example below is real output at that size.

The biggest saving comes from drift detection. At save time, the server records a content hash for every file with uncommitted changes. On load, it compares those hashes against the working tree and tells Claude exactly which files changed after the checkpoint. Everything else in the brief can be trusted as-is, so Claude re-reads only what it has to.

How it works

Code

  Session 1                                     Session 2 (after crash / /clear)
  ─────────                                     ────────────────────────────────
  Claude ──save_session_checkpoint──┐       ┌──load_session_checkpoint── Claude
         goal, tasks, summary,      │       │   compact markdown brief
         next steps, decisions,     ▼       │   + "changed since checkpoint"
         files, commands      ┌─────────────────────┐
                              │ <project>/          │
     server adds:             │ .claude-checkpoint  │◀── git: branch, HEAD,
     git branch/HEAD,         │ .claude-checkpoint  │    dirty files + hashes
     dirty files + hashes,    │   .prev (backup)    │
     redacts secrets          └─────────────────────┘

Claude supplies the meaning: the goal, progress, decisions, next steps, and which commands mattered.
The server supplies the facts: git branch and HEAD, every uncommitted or untracked file with its content hash, and timestamps.
The server instructions teach Claude when to act. Claude is told to load at the start of a session and to save after milestones, before risky operations, and when the conversation gets long. It doesn't need to be prompted every time.

Installation

Requirements: Node.js 20+ and git. Git is optional, but without it you lose drift detection.

git clone https://github.com/tenlean/claude-checkpoint-mcp.git
cd claude-checkpoint-mcp
npm install
npm run build

The server entry point is now at dist/index.js.

Configuration

Claude Code

As a plugin (easiest). This repo is also a Claude Code plugin marketplace. You don't need to clone or build anything:

Terminal

claude plugin marketplace add tenlean/claude-checkpoint-mcp
claude plugin install claude-checkpoint-mcp@tenlean

Restart Claude Code, then /mcp should show plugin:claude-checkpoint-mcp:claude-checkpoint as connected.

Manual setup. If you cloned the repo, register the server once for your user account, so it's available in every project:

# Run from the claude-checkpoint-mcp directory
claude mcp add --scope user checkpoint -- node "$PWD/dist/index.js"

Use an absolute path. A user-scoped server is launched from whichever project you open Claude Code in. A relative path like ./dist/index.js would resolve against that project, not this repo. "$PWD/dist/index.js" expands to the absolute path when you run the command, which is what gets saved.

Check that it's registered:

Terminal

claude mcp list

Inside a session, /mcp should show checkpoint as connected.

Project-scoped alternative. To share the server with a team through version control, add it to the project's .mcp.json:

config.json

{
  "mcpServers": {
    "checkpoint": {
      "command": "node",
      "args": ["/absolute/path/to/claude-checkpoint-mcp/dist/index.js"]
    }
  }
}

Either way, add the checkpoint files to the project's .gitignore, or to your global gitignore:

gitignore

.claude-checkpoint*

Claude Desktop (`claude_desktop_config.json`)

Open the config file:

OS	Path
macOS	`~/Library/Application Support/Claude/claude_desktop_config.json`
Windows	`%APPDATA%\Claude\claude_desktop_config.json`

Add the server under mcpServers, using the absolute path to your local build:

config.json

{
  "mcpServers": {
    "checkpoint": {
      "command": "node",
      "args": ["/absolute/path/to/claude-checkpoint-mcp/dist/index.js"],
      "env": {
        "CHECKPOINT_PROJECT_ROOT": "/absolute/path/to/your/project"
      }
    }
  }
}

Restart Claude Desktop after saving the file.

Claude Desktop has no notion of a "current project". Use CHECKPOINT_PROJECT_ROOT to set the default project, or have Claude pass projectRoot on each call ("save a checkpoint for /home/me/code/my-app"). See project root resolution.

Other MCP clients

Any MCP client that supports the stdio transport can run the server:

node /absolute/path/to/claude-checkpoint-mcp/dist/index.js

Usage

The server's built-in instructions cover the common cases automatically. You can also ask Claude directly.

Save:

"Checkpoint our progress."
"Save a checkpoint before you run the migration."
"Update the checkpoint. Merge in what we just did."

Resume (in a fresh session):

"Resume where we left off."
"Load the checkpoint and continue."

Example resume brief

This is real output from load_session_checkpoint. In the scenario, one file was committed unchanged after the save, and a teammate then edited session.ts:

markdown

# Resuming: my-app (checkpoint saved 2m ago, 2026-10-08 02:23:55 UTC)
Branch `feat/github-oauth` @ b2ef1b591 (uncommitted changes)

## Goal
Add GitHub OAuth login with persistent sessions

## Tasks
- [x] OAuth callback route
- [~] Session cookie persistence
- [ ] Logout endpoint

## Where things stand
Callback exchanges the code and creates a session, but the cookie is dropped on reload. Suspect SameSite/secure flags in dev.

## Next steps
1. Set sameSite: 'lax' and secure only in production in src/auth/session.ts
2. Re-run npm test -- auth
3. Start the logout endpoint

## Decisions & gotchas
- Use iron-session, not express-session (needs edge runtime support)
- Don't mock the GitHub API in e2e tests; use the recorded fixtures in test/fixtures

## Files touched (3)
- src/auth/session.ts (M) — cookie options
- src/auth/callback.ts (M)
- src/auth/session.spec.ts (??)

## Recent commands (last 2, oldest first)
- ✓ `GITHUB_CLIENT_SECRET=«redacted» npm run dev`
- ✗ exit 1 `npm test -- auth` — 2 failing in session.spec.ts: cookie missing after reload

## Since this checkpoint
- 1 new commit(s) on HEAD
- ⚠ Changed after the checkpoint, re-read before editing: `src/auth/session.ts`

callback.ts was committed after the save, but its content didn't change, so it isn't flagged. Only session.ts needs to be re-read.

Task markers: [x] done · [~] in progress · [ ] pending · [!] blocked.

Tool reference & examples

`save_session_checkpoint`

Writes <projectRoot>/.claude-checkpoint.

Parameter	Type	Required	Description
`goal`	`string` (≤ 500)	✅	Primary objective of the session
`tasks`	`{ description, status }[]` (≤ 30)		`status`: `pending` · `in_progress` · `done` · `blocked`
`summary`	`string` (≤ 4000)		Where things stand: what works, what's broken, what you were in the middle of
`nextSteps`	`string[]` (≤ 20)		Ordered next actions for whoever resumes
`decisions`	`string[]` (≤ 20)		Key decisions, constraints, dead ends to avoid
`modifiedFiles`	`{ path, note? }[]` (≤ 100)		Files to annotate, or committed files to include. Uncommitted git changes are detected automatically. Absolute paths inside the project are stored as relative.
`recentCommands`	`{ command, exitCode?, note? }[]` (≤ 50)		Significant commands, oldest first. Secrets are redacted.
`mode`	`"replace"` \| `"merge"`		Default `replace`. See below.
`projectRoot`	`string` (absolute)		Overrides root resolution

Full save:

config.json

{
  "goal": "Add GitHub OAuth login with persistent sessions",
  "tasks": [
    { "description": "OAuth callback route", "status": "done" },
    { "description": "Session cookie persistence", "status": "in_progress" },
    { "description": "Logout endpoint", "status": "pending" }
  ],
  "summary": "Callback exchanges the code and creates a session, but the cookie is dropped on reload. Suspect SameSite/secure flags in dev.",
  "nextSteps": [
    "Set sameSite: 'lax' and secure only in production in src/auth/session.ts",
    "Re-run npm test -- auth"
  ],
  "decisions": ["Use iron-session, not express-session (needs edge runtime support)"],
  "modifiedFiles": [{ "path": "src/auth/session.ts", "note": "cookie options" }],
  "recentCommands": [
    { "command": "GITHUB_CLIENT_SECRET=gh_live_8f2a91 npm run dev", "exitCode": 0 },
    { "command": "npm test -- auth", "exitCode": 1, "note": "2 failing in session.spec.ts" }
  ]
}

Response (text shown to the model):

Code

Checkpoint saved to /home/me/code/my-app/.claude-checkpoint (2202 bytes, replace).
3 task(s), 3 file(s), 2 command(s) on feat/github-oauth@b2ef1b591.
⚠ Redacted 1 secret-looking value(s).

Incremental update with merge:

config.json

{
  "goal": "Add GitHub OAuth login with persistent sessions",
  "mode": "merge",
  "tasks": [
    { "description": "Session cookie persistence", "status": "done" },
    { "description": "Logout endpoint", "status": "in_progress" }
  ],
  "recentCommands": [{ "command": "npm test -- auth", "exitCode": 0, "note": "all green" }]
}

Field	`replace`	`merge`
`goal`	set	set
`tasks`	set	updated by matching `description`; new tasks appended
`summary`, `nextSteps`	set	replaced if provided, otherwise kept
`decisions`	set	appended (deduplicated)
`recentCommands`	set	appended; the oldest are dropped beyond 50
`modifiedFiles`	fresh git scan + provided	fresh git scan + provided + previously recorded
`id`, `createdAt`	new	preserved

Structured output (structuredContent):

config.json

{
  "path": "/home/me/code/my-app/.claude-checkpoint",
  "bytes": 2202,
  "mode": "replace",
  "counts": { "tasks": 3, "modifiedFiles": 3, "recentCommands": 2, "redactions": 1 },
  "warnings": ["Redacted 1 secret-looking value(s)."]
}

`load_session_checkpoint`

Read-only. Reads the checkpoint, checks for drift, and returns the brief.

Parameter	Type	Required	Description
`format`	`"brief"` \| `"full"`		Default `brief` (markdown, as above). `full` returns the complete checkpoint JSON plus drift.
`projectRoot`	`string` (absolute)		Overrides root resolution

Examples:

config.json

{}

config.json

{ "format": "full", "projectRoot": "/home/me/code/my-app" }

Structured output (structuredContent):

config.json

{
  "found": true,
  "path": "/home/me/code/my-app/.claude-checkpoint",
  "fromBackup": false,
  "updatedAt": "2026-10-08T02:23:55.477Z",
  "drift": {
    "branchChanged": false,
    "currentBranch": "feat/github-oauth",
    "commitsSince": 1,
    "changedSince": ["src/auth/session.ts"]
  },
  "warnings": []
}

If no checkpoint exists, the tool returns found: false with a "nothing to resume" message. That isn't treated as an error.

How the project root is chosen

The projectRoot argument
The CHECKPOINT_PROJECT_ROOT environment variable
The client's first file:// root, if the client supports MCP roots
The server process's working directory

The path must be absolute and must be an existing directory. Symlinks are resolved. The file is always written at exactly <root>/.claude-checkpoint.

The `.claude-checkpoint` file

This is plain, versioned JSON, so it's easy to read, diff, or edit by hand. Real example:

config.json

{
  "version": 1,
  "id": "ee5507c0-855e-44a5-85c1-d97b767537c9",
  "createdAt": "2026-10-08T02:23:55.477Z",
  "updatedAt": "2026-10-08T02:23:55.477Z",
  "generator": { "name": "claude-checkpoint-mcp", "version": "0.1.0" },
  "project": { "name": "my-app" },
  "git": {
    "branch": "feat/github-oauth",
    "head": "b2ef1b5919ee5d456ea146c9362a7abc92b1e556",
    "dirty": true
  },
  "goal": {
    "primary": "Add GitHub OAuth login with persistent sessions",
    "tasks": [
      { "description": "OAuth callback route", "status": "done" },
      { "description": "Session cookie persistence", "status": "in_progress" },
      { "description": "Logout endpoint", "status": "pending" }
    ]
  },
  "summary": "Callback exchanges the code and creates a session, but the cookie is dropped on reload. Suspect SameSite/secure flags in dev.",
  "nextSteps": [
    "Set sameSite: 'lax' and secure only in production in src/auth/session.ts",
    "Re-run npm test -- auth",
    "Start the logout endpoint"
  ],
  "decisions": [
    "Use iron-session, not express-session (needs edge runtime support)",
    "Don't mock the GitHub API in e2e tests; use the recorded fixtures in test/fixtures"
  ],
  "modifiedFiles": [
    { "path": "src/auth/session.ts", "status": "M", "source": "git", "note": "cookie options", "hash": "9ec893ef673dac860e7e2b6fcaad602983eeb0b1" },
    { "path": "src/auth/callback.ts", "status": "M", "source": "git", "hash": "f3ecc849c3875d4f11bb42ae0e5ab6c71931d7f1" },
    { "path": "src/auth/session.spec.ts", "status": "??", "source": "git", "hash": "9daeafb9864cf43055ae93beb0afd6c7d144bfa4" }
  ],
  "recentCommands": [
    { "command": "GITHUB_CLIENT_SECRET=«redacted» npm run dev", "exitCode": 0, "at": "2026-10-08T02:23:55.477Z" },
    { "command": "npm test -- auth", "exitCode": 1, "note": "2 failing in session.spec.ts: cookie missing after reload", "at": "2026-10-08T02:23:55.477Z" }
  ],
  "meta": { "redactions": 1, "truncated": false }
}

Field	Notes
`version`	Schema version. Older versions are migrated on load; unknown versions are rejected.
`id` / `createdAt`	Stable across `merge` saves; new on `replace`
`git`	`null` outside a git repo, or before the repo's first commit
`modifiedFiles[].status`	Git porcelain code (`M`, `A`, `D`, `R`, `??`), or `M` for files reported only by Claude
`modifiedFiles[].source`	`git` (detected) or `agent` (reported by Claude, or carried over from an earlier merge)
`modifiedFiles[].hash`	Git blob hash of the working-tree content at save time; drives drift detection
`meta.truncated`	`true` if anything was dropped to fit list or size limits

Paths are always relative to the project root. The file never stores absolute paths.

Security & privacy

Local only. There are no network calls. The server reads git metadata and one file, and writes one file.
Secret redaction. The following are replaced with «redacted» in commands, notes, summaries, tasks and decisions before anything touches disk:
- *_KEY=, *_TOKEN=, *_SECRET=, *PASSWORD= assignments, including Header: value and JSON forms
- Authorization: Bearer … headers
- credentials in URLs (postgres://user:pass@…)
- --password / --token / --api-key / --secret flags
- bare sk-…, ghp_…, github_pat_…, AKIA… and xox?-… tokens
Redaction is a safety net, not a guarantee, so keep the file out of version control.
Owner-only, crash-safe writes. Files are written with mode 0600. Each save writes a temp file, fsyncs it, and renames it into place, so a crash mid-save can't leave a half-written checkpoint.
Automatic backup. The previous valid checkpoint is kept as .claude-checkpoint.prev. If the main file is corrupt, load falls back to the backup and says so. A corrupt file never overwrites a good backup.
Bounded size. Every field has a length cap, and the file is capped at 64 KB (the oldest commands are dropped first), so a checkpoint can't grow into a token sink.
No shell. Git runs through execFile with a 3-second timeout and GIT_OPTIONAL_LOCKS=0, so it never contends with your own git commands.
Doesn't touch your config. If the checkpoint isn't git-ignored, the save response warns you. It never edits .gitignore for you.
Safe with parallel tool calls. Tool calls are serialized inside the server, so concurrent merge saves can't lose updates.

Troubleshooting

Symptom	Fix
`checkpoint` doesn't appear in `/mcp`	Run `claude mcp list` and check that the path is absolute and `dist/index.js` exists (`npm run build`).
Checkpoint is written to the wrong directory	The server fell back to its working directory. Pass `projectRoot`, or set `CHECKPOINT_PROJECT_ROOT`.
`projectRoot must be an absolute path`	Use a full path such as `/home/me/code/app`, not `./app`.
Brief says "Saved commit … is no longer reachable"	The branch was rebased or reset after the save. Drift can't be computed against history, so treat the flagged files as needing a re-read.
Warning: "not git-ignored"	Add `.claude-checkpoint*` to `.gitignore`.
No "Since this checkpoint" section	The project isn't a git repo, or had no commits at save time.

Server logs go to stderr. Stdout is reserved for the MCP protocol.

Development

Terminal

npm run typecheck   # strict TypeScript, src + tests
npm test            # unit tests + in-memory MCP end-to-end tests (vitest)
npm run build       # compile to dist/
npm run inspect     # open the MCP Inspector against dist/index.js

Code

src/
├── index.ts    # entry point: stdio transport, signals, stderr logging
├── server.ts   # McpServer construction + server instructions
├── tools.ts    # save/load tool schemas and handlers
├── schema.ts   # zod schema for the checkpoint file (v1) + migrations
├── store.ts    # project root resolution, atomic I/O, backup/fallback
├── git.ts      # branch/HEAD/status snapshot, blob hashing, drift detection
├── redact.ts   # secret scrubbing
└── render.ts   # checkpoint → markdown resume brief

Built with the official @modelcontextprotocol/sdk and zod.

License

MIT