Seamcheck

Your AI wrote 400 lines. Which of them are actually wired to anything?

Seamcheck reads a Django + JavaScript project and tells you what connects to what — which fetch() lands on which view, which template element the JS is reaching for, which CSS rule nothing has referenced since 2023. Then it tells you what it couldn't work out, which turns out to be the part that matters.

No SaaS. No upload. One command, one HTML file, and an exit code for CI.

The four answers

Every dead-code tool ever written has told you something was unused and been wrong, and you stopped trusting it. Seamcheck has a fourth answer:

That last row is the whole product. A page reached by an <a href> looks exactly like a dead one if you only parse fetch() calls. Seamcheck says so instead of guessing. On a 700-URL project that's the difference between a report you act on and 668 lies.

It also reports its own coverage — how much of each file it actually reasoned about. No other tool I've found will tell you where it wasn't looking.

What it found in the project it was built on

Not hypotheticals. Real bugs, in a real 36,000-symbol codebase, found while writing this:

• Five CSS custom properties in a loaded stylesheet that resolve to nothing — --text-primary, --border-color and friends. Those declarations render nothing today.
• An endpoint reported missing that turned out to be <str:division_id> matching a deliberate 'all' sentinel — so I fixed the matcher instead of "fixing" the code.
• 65 API routes whose path appears in no source file at all.
• 46 DOM elements written by more than one module — the reason a display bug survives being "fixed" in one of them.

Install

pip install seamcheck

Then two things in settings.py:

INSTALLED_APPS = [..., "seamcheck"]

SEAMCHECK_CONFIG = {
    "urlconf_module": "myproject.urls",
    "templates_root": "myapp/templates",
    "js_source_root": "myapp/static/js",
    "css_source_root": "myapp/static/css",
    "first_party_prefixes": ["myapp", "myproject"],
}

Every project-specific path lives in that dict. Nothing is hardcoded anywhere in the extractors — which is how this was lifted out of the project it grew in without touching a line of it.

You need Node on PATH. The JS and CSS parsers run on it. You do not need npm or node_modules — acorn and postcss ship inlined in the wheel. If Node is missing, Seamcheck says so and gives you the Python half rather than dying.

Use

seamcheck help              # every command, one line each
seamcheck scan              # scan, summary, snapshot for later diffs
seamcheck check             # exit 1 on new findings. This is the CI one.
seamcheck map               # the UI, one self-contained HTML file
seamcheck serve             # ...opened from your phone
seamcheck explain <id>      # one symbol, with the code around it

It finds your project by walking up to the nearest manage.py and reading the settings module out of it, so it works from anywhere inside the tree. Everything is also available as python manage.py seamcheck ... if you prefer — same code, one implementation.

The UI

One file, no network, opens on a phone. A left rail of views; a canvas that draws every symbol a page touches at once — 1,366 of them on the biggest page here — with the broken ones filled in red so they find you rather than the other way round.

Click any node and it lights the line through it: page → module → fetch() → URL → view, each hop with the real source, and a button to show the whole enclosing function. Or isolate that one chain and drop everything else.

There's a Files view too — your actual folder tree, with a bar per file showing how many of its declarations Seamcheck reasoned about. Because "no findings" and "never looked" are not the same sentence.

seamcheck serve            # open it from your phone
seamcheck serve --tunnel   # ...from anywhere

Nothing is uploaded. --serve is a socket on your machine that dies with the command.

Per-commit

seamcheck backfill 20       # scan the last 20 commits

Now the map has a commit picker. Pick one and see what that commit changed — added, removed, status flipped — including things it deleted, which no longer exist to be drawn and get named instead.

CI

seamcheck check --since $BASE_SHA

1 = new findings. 2 = no baseline, so the gate didn't run. 0 = clean. That distinction matters: a gate that never ran is not a gate that passed.

Agents

Seamcheck ships an MCP server, so your assistant can check its own work before it hands it to you. It speaks over stdin/stdout — no port, no daemon, no network.

Claude Code

claude mcp add seamcheck -- seamcheck-mcp

Cursor, Windsurf, Claude Desktop — in the MCP config:

{
  "mcpServers": {
    "seamcheck": {
      "command": "seamcheck-mcp",
      "cwd": "/path/to/your/django/project"
    }
  }
}

cwd matters: Seamcheck reads a real project, so it needs to start in one. It finds the settings module the same way the CLI does — the nearest manage.py — so the project root is the right answer.

Four tools: seamcheck_check (scan, report findings new since the last snapshot), seamcheck_report (the digest), seamcheck_explain (one symbol with its evidence), and seamcheck_triage (record a disposition).

There is also an AGENTS.md with the one rule that matters: never delete something because it came back uncertain. That is the scan saying it has no evidence, not that the code is dead.

What it can't do

Written down because a tool that hides its blind spots is worse than no tool:

• Django + vanilla JS. No React, Vue, or TypeScript yet.
• Celery, Redis, WebSockets and Stripe aren't traced. Anything reached only through those is invisible, and the UI says so rather than showing a confident zero.
• A URL built at runtime stays uncertain. The prefix is recorded, never a guess.
• It has been run against one real project. Mine. That's one more than most tools at this stage and far fewer than you'd want.

Contributing

Issues and PRs welcome. One house rule, and it's the reason the tool is worth anything: never make a claim the scan can't evidence. If you can't prove it, it's uncertain, and the note says which evidence source was missing.

License

MIT.