stalemap

Coding agents learn libraries from training data that stops at a cutoff date. When your project pins newer versions, the agent writes code for the old API: maxSteps against AI SDK 7, required_error against zod 4, middleware.ts against Next 16.

stalemap finds the dependencies that changed after your model's training cutoff and tells the agent what changed, in three ways:

• Notes: a short, ranked list of changes written into AGENTS.md or CLAUDE.md, so the agent reads it before it starts.
• Edit-time guard: after each edit, the project's own type-check. If the code uses an API that changed after the cutoff, the agent gets the compiler error and the matching note (or the release-note or upgrade-guide section that explains it) right away. It also reports the code that still compiles but uses something that moved.
• search_changes: an MCP tool the agent can ask in its own words, such as "resolve alias in next.config", to get the matching changes with their sources.

It works for JavaScript and TypeScript projects, with Claude Code, Cursor, Codex, OpenCode or any MCP client.

In a blind, pre-registered benchmark of 66 tasks built from changes released after June 2026, claude-sonnet-5-5 agents passed 89% of sessions with stalemap, against 68% with no help and 73% with a plain tsc --noEmit hook after each edit. See Results.

Status

• npm: the latest release is stalemap 0.4.1: the build tested in held-out v4 (0.4.0), plus a one-line footer in the notes block. npx stalemap, the Claude Code plugin and the GitHub Action all run it. See the changelog.
• The project is early, and maintained by one person.

Install

Claude Code plugin

/plugin marketplace add Umair/stalemap
/plugin install stalemap@stalemap

The plugin adds:

• a SessionStart hook that puts the notes into Claude's context for the session's model (on startup, after /clear and after compaction; it writes no files);
• a PostToolUse hook that runs the edit-time guard after each Write or Edit;
• the stalemap MCP server and two skills (/stalemap:sync writes the notes block; upgrade tells Claude to look up a package's changes before using or upgrading it).

The hooks and the MCP server run npx -y stalemap@latest, so they use the latest npm release. Its MCP tools are search_changes, package_changes, project_changes and check_notes.

Command line

npx stalemap            # preview what changed and the block it would write
npx stalemap sync       # write the block into AGENTS.md or CLAUDE.md
npx stalemap check      # for CI: exit 1 when the block is missing or stale
npx stalemap guard src/**/*.ts   # run the guard by hand

The block sits between <!-- stalemap:start --> and <!-- stalemap:end -->. Text outside it is never touched. Claude Code reads CLAUDE.md; if your notes live in AGENTS.md, add @AGENTS.md to CLAUDE.md or pass --target CLAUDE.md.

Other agents: setup --agent

stalemap setup --agent cursor             # or codex, opencode, claude
stalemap setup --agent codex --dry-run    # print the changes, write nothing

One command per agent writes the notes, registers the MCP server and installs the guard as the agent's post-edit hook, as project files you can commit. It merges into existing config files, keeps entries it didn't write, and re-running it changes nothing.

One caveat: it hasn't been tried in a real Cursor, Codex or OpenCode install yet. Cursor doesn't pass a postToolUse hook's context to the model yet, so setup adds a stop-hook fallback that sends unreported findings as a follow-up message.

Any MCP client

{ "mcpServers": { "stalemap": { "command": "npx", "args": ["-y", "stalemap@latest", "mcp"] } } }

GitHub Action

- uses: Umair/stalemap@main
  with:
    model: claude-opus-5-5          # fail CI when the notes are missing or stale
    # mode: comment                 # or comment on PRs that change dependencies

Comment mode needs permissions: pull-requests: write. It lists each changed dependency (what the model knows → what's pinned) with its notes, and updates the comment on later pushes.

What the notes look like

For a Next.js + AI SDK app and claude-sonnet-4-5 (cutoff 2025-07-31), excerpt:

**ai** 4.3.16 → 7.0.142 (major)
- `CoreMessage` was removed; use `ModelMessage`. [types]
- `convertToCoreMessages` was removed; use `convertToModelMessages`. [types]
- `streamText()` options no longer accept `maxTokens`, `maxSteps`, `toolCallStreaming`, … [types]

**next** 15.4.0 → 16.4.2 (major)
- `revalidateTag()` now requires `profile` (in `next/cache`) [types]
- `NextMiddleware` is deprecated: Use `NextProxy` instead. Middleware has been renamed to Proxy. (in `next/server`) [types]

Full output: examples/next-ai-app.claude-sonnet-4-5.md.

How it works

1. Which model? --model, or the model configured for Claude Code, Codex, OpenCode or Gemini CLI, or $ANTHROPIC_MODEL. The training cutoff comes from models.dev (with a built-in fallback table), or pass --cutoff YYYY-MM-DD.
2. What did the model know? For each dependency, the newest stable release published at least 30 days before the cutoff (--margin).
3. Which dependencies? Direct dependencies your code imports (scanned locally), plus the ones a config file configures (tsconfig.json, next.config.*, the Prisma schema, Vitest and ESLint configs, and others). --all checks every direct dependency. Pinned versions come from node_modules or the lockfile (npm, pnpm, yarn, bun).
4. What changed?
   • Types: both versions' .d.ts files are downloaded and compared with the TypeScript compiler API: removed, renamed and moved exports, new required parameters, removed or newly required options, and new @deprecated tags with their hints.
   • Release notes: the package's changelog or GitHub Releases, scored for breaking-change signals and for the APIs you use. A removal gets its replacement from a rename the changelog announces.
   • Upgrade guides (--guides): for changes that never reach a type signature, like a new default or a renamed file convention. Claude turns each guide into short notes, and a note is kept only if it quotes the guide.
   • Verified examples (--examples): a Before → After line under the top notes, written by Claude and kept only if it compiles against the version you pin.
5. Fit the budget. Notes about what your project uses come first: imported APIs, members and props, config keys it sets, file names. The default budget is 1,800 tokens (--budget).

The guard runs after each edit. It runs the project's own tsc and reports what it finds, in this order:

1. Compile errors that come from a dependency that changed after the cutoff, with the matching note as the fix. When no note explains the error, it shows the matching section from the package's type changes, release notes or upgrade guide, found by searching with the error and the code around it.
2. Things that still type-check but changed:
   • config keys that moved (experimental.ppr in Next 16);
   • moved members (HttpStatusCode.PayloadTooLarge → ContentTooLarge in axios 1.20);
   • renamed file conventions (middleware.ts → proxy.ts);
   • tsconfig.json options the project's TypeScript rejects.
3. The compiler's other errors: in the edited file, new ones in files that import it, and a few elsewhere. These don't claim a dependency changed.

So a plain type-check hook is a subset of the guard. STALEMAP_GUARD_TSC=0 limits the guard to dependency changes. Deprecations are reported only with STALEMAP_GUARD_DEPRECATIONS=1.

search_changes (also stalemap search <query>) searches everything stalemap found for the project's dependencies: every type change, every release-note item, cached upgrade-guide notes and, for a new major, the guides' text. Ranking is BM25 over words and split identifiers (resolveAlias matches "resolve alias"), weighted toward what the project uses. The first search builds an index from the analysis caches; later on