_ _ _ ____ ___ ____ ____ _  _ ____ ____ _  _ ____    ____ ____ _  _ ____ _  _ ____ ____
| | | |__|  |  |___ |__/ |\/| |__| |__/ |_/  [__  __ |__/ |___ |\/| |  | |  | |___ |__/
|_|_| |  |  |  |___ |  \ |  | |  | |  \ | \_ ___]    |  \ |___ |  | |__|  \/  |___ |  \

watermarks-remover

Agent skill + stdlib Python service to strip multi-vendor AI provenance marks from text and files — for privacy and hygiene on content you own. The skill is a thin client: it drives the machinery over HTTP, so the agent host needs no Python.

Layer	Target	How
A	Invisible Unicode, exotic spaces, bidi, tag chars	Deterministic Python scripts
B	Statistical (token-sampling) text watermarks	Agent rewrite + optional rewrite_text.py hook
Files	C2PA / EXIF / XMP / doc props	PNG, JPEG, WebP, AVIF, HEIC, BMP, GIF, TIFF, SVG, PDF, DOCX, XLSX, PPTX, EPUB, ODT, HTML, Markdown, MP4/MOV/M4A/M4V, WAV, MP3, FLAC

Vendors / ecosystems (class-level): Claude, Gemini / SynthID-Text, OpenAI provenance surfaces, open-LLM Kirchenbauer-style (green-list) and keyed-Gumbel / EXP (Aaronson) marks.

Latest release: v0.7.0

Skill path: skills/remove-ai-marks/
Service path: service/
(migration: formerly remove-claude-marks; slash alias /remove-claude-marks still documented)

Install (agent skill)

The skill ships no code — it calls the service over HTTP. Install the skill (markdown only) and start the service, then set WATERMARKS_SERVICE_URL if it is not http://127.0.0.1:8765.

In Claude Code, the fastest route is the bundled plugin marketplace — no clone, and it updates in place. Everywhere else, one installer covers every supported host (Python 3.10+ stdlib, no dependencies):

python3 install_skill.py --skill remove-ai-marks --target claude-code

Host	Target	Lands in
Claude Code (personal)	--target claude-code	~/.claude/skills/<skill> (honors CLAUDE_CONFIG_DIR)
Claude Code (project)	--target claude-project --project-dir PATH	PATH/.claude/skills/<skill>
Cowork, claude.ai, cloud sessions, routines	--target cowork	dist/<skill>.zip to upload under Customize → Skills
Cursor	--target cursor (default)	~/.cursor/skills/<skill>

Shipped skills: remove-ai-marks (full, service-backed) and clean-user-facing-text (text only, self-contained). --list prints them. Existing installations are preserved unless you pass --force; replacement is staged first and the previous install is kept as a uniquely named backup. --link symlinks this checkout instead of copying, so edits are picked up live. On Windows, use py install_skill.py ...; the install-skill.sh wrapper is provided for macOS/Linux shells.

Before writing anything, the installer validates the skill against the Agent Skills packaging rules that claude.ai uploads and the Skills API enforce: spec-only frontmatter (name, description, license, compatibility, metadata, allowed-tools), a lowercase hyphenated name of at most 64 characters matching the directory, a non-empty description of at most 1024 characters. The Cowork bundle additionally has to fit the 30 MB upload limit, which the packager enforces.

Automatic cleaning via hook (deterministic)

A skill is an instruction: the model decides whether to invoke it, and the model is the thing producing the marks. A hook is executed by the harness on every matching tool call, cooperation not required. That makes the hook the deterministic half of this workflow.

The plugin registers a PostToolUse hook on Write|Edit|MultiEdit|NotebookEdit that runs service/scripts/hook_written_file.py against the file the agent just wrote. Two modes, matching the pre-commit convention of check-by-default:

Mode	Behaviour
check (default)	Reports provenance marks, leaves the file alone. Findings go to the model (exit 2), so it can offer to clean them.
clean	Strips the marks in place, then tells the model the file on disk changed.

Set the mode from the plugin's settings (Hook mode in /plugin manage, read by the hook as CLAUDE_PLUGIN_OPTION_HOOK_MODE), or with WATERMARKS_HOOK_MODE=clean in the environment. The hook command deliberately does not interpolate ${user_config.hook_mode}: Claude Code refuses to run a hook that references an option the user has never opened /plugin manage to set — a declared default does not satisfy it — so interpolating it would mean the hook silently never runs on a fresh install. Detection reuses audit_lib's scan_file / is_actionable, so the hook, the pre-commit gate, and the CI SARIF export agree on what counts as actionable; cleaning shells out to clean_file.py, so no cleaning logic is duplicated. clean mode writes to a sibling temp file and swaps only on a real difference, so files that were already clean keep their mtime and don't retrigger file watchers.

Without the plugin, wire it in ~/.claude/settings.json (or a project .claude/settings.json) yourself:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write|Edit|MultiEdit|NotebookEdit",
        "hooks": [
          {
            "type": "command",
            "command": "python3",
            "args": ["/path/to/watermarks-remover/service/scripts/hook_written_file.py",
                     "--mode", "check"],
            "timeout": 30
          }
        ]
      }
    ]
  }
}

On Windows, replace python3 with py.

What a hook cannot do. No hook can rewrite the assistant's chat message before you read it. Claude Code's Stop hook receives last_assistant_message read-only, and there is no pre-send filter for final responses — the same limit this project already documents for Cursor rules. So the deterministic guarantee covers files the agent writes, plus the pre-commit gate for anything on its way into git. Text that only ever exists in the chat transcript still depends on the skill workflow, which is model-instruction-based and therefore best-effort.

Claude Code plugin (marketplace)

The repository is also a Claude Code plugin and a single-plugin marketplace (.claude-plugin/), so both skills install and update in two commands, no clone or script required:

/plugin marketplace add guillaumemeyer/watermarks-remover
/plugin install watermarks-remover@watermarks-remover