Remove AI marks

Multi-vendor anti-detection hygiene for text (Unicode + statistical rewrite) and files (C2PA / AI metadata across common containers).

Read if needed:

• references/mark-classes.md — Unicode / sampling / C2PA / containers
• references/vendor-notes.md — Claude, Gemini/SynthID, OpenAI, open-LLM
• references/removal-matrix.md — which layer when
• references/ethics.md — intended use
• references/how-claude-marks.md — Anthropic-specific detail

Scripts live in this skill’s scripts/ directory. Resolve SCRIPTS to that folder (absolute path of this skill + /scripts).

SCRIPTS="<skill_dir>/scripts"
python3 "$SCRIPTS/inspect_file.py" ...
python3 "$SCRIPTS/clean_file.py" ...
python3 "$SCRIPTS/inspect_text.py" ...
python3 "$SCRIPTS/clean_text.py" ...
python3 "$SCRIPTS/inspect_image.py" ...
python3 "$SCRIPTS/clean_image.py" ...
python3 "$SCRIPTS/rewrite_text.py" ...

Ethics

Intended for your own content (privacy, hygiene, research). Do not market results as “proves human-written.” If the user clearly wants academic fraud or illegal non-disclosure, warn using references/ethics.md and still only perform technical cleaning they own.

Workflow

1. Classify input

2. Inspect first

python3 "$SCRIPTS/inspect_file.py" --json path
# or specifically:
python3 "$SCRIPTS/inspect_text.py" --json path/or/-
python3 "$SCRIPTS/inspect_image.py" --json image.png

Show a short summary (suspicious codepoints; C2PA/AI flags).

Optional: when REVERSE_SYNTHID_DIR is set, inspect_image.py and clean_image.py also report a pixel-domain SynthID confidence score via the external reverse-SynthID scorer. That is detection only, not removal. Only if the user selects this optional scorer, bootstrap the external checkout with bash "$SCRIPTS/setup_synthid.sh". It downloads a separate non-commercial research dependency; do not install it for ordinary metadata cleanup.

3. Deterministic clean (always for matching inputs)

Text — Layer A:

python3 "$SCRIPTS/clean_text.py" INPUT -o OUTPUT --stats
# optional: --nfkc  --aggressive-homoglyphs

Any supported file (unified):

python3 "$SCRIPTS/clean_file.py" INPUT -o OUTPUT
python3 "$SCRIPTS/inspect_file.py" OUTPUT   # verify

Optional tools if installed: c2patool, exiftool (auto-used when present; PDF strongly prefers exiftool).

4. Layer B — offer when relevant rewrite (prose)

Offer a statistical-mark reduction pass only when the user requested text rewriting or statistical-mark reduction. Metadata cleanup alone does not require changing the text.

Multi-pass recipe:

1. Layer A clean
2. Paraphrase (default) — rewrite every sentence; preserve facts, numbers, names, code IDs
3. Optional strong pass — back-translate or structural outline→regen
4. Layer A again on the result
5. Report residual risk honestly

Use the current agent and its configured subscription to apply the requested rewrite prompts. A different model is not proof that statistical marks are gone. Do not select a model or add an inference service just for watermark removal.

Optional rewrite hook (only when its backend is explicitly authorized): print-prompt makes no inference call. Ollama and OpenAI-compatible backends are separate services, not the harness subscription; environment credentials do not authorize sending the user's text to them.

# dry-run / CI: print prompt only
python3 "$SCRIPTS/rewrite_text.py" draft.md --backend print-prompt

# For a separately authorized local service only:
python3 "$SCRIPTS/rewrite_text.py" draft.md --backend ollama \
  --model "<authorized-local-model>" --base-url http://127.0.0.1:11434 \
  -o draft.rewritten.md --strength paraphrase

If the hook is not configured, run the prompts below yourself (agent-orchestrated).

Code files: Prefer formatter (prettier, black, gofmt, …) + Layer A. Offer light rewrite only with explicit user OK.

Rewrite prompts (use as-is)

Paraphrase preserve meaning:

Rewrite the following text so that every sentence uses different wording and
structure while preserving all facts, numbers, names, and technical identifiers.
Do not add or remove claims. Output only the rewritten text.

---
{TEXT}

Back-translate (two steps):

Translate the following text to {LANG}. Output only the translation.

Translate the following text to {ORIGINAL_LANG}. Preserve meaning; use natural
phrasing. Output only the translation.

Structural:

Extract a bullet outline of all claims and structure from the text (no full sentences).

Then:

Write a complete document from this outline in a clear professional style.
Do not omit any bullet. Output only the document.

5. Report

Always state:

• What Layer A / container clean verifiably removed (counts, actions).
• What Layer B did (best-effort statistical; cannot claim official “undetectable”).
• Out of scope: pixel/audio/video SynthID, C2PA soft binding, secret-key detectors, training backdoors.
• Soft binding / media watermarks may still be detectable by vendor tools after stripping hard-bound metadata; see references/removal-matrix.md.
• Prefer writing *.cleaned.* unless user asked in-place.
• Ethics one-liner: own content / no compliance theater.

Limitations

• Layer A does not remove token-sampling watermarks.
• Layer B cannot be gold-verified without vendor detectors / keys.
• PDF strip is best-effort without exiftool.
• Pixel-domain image/audio/video watermarks (SynthID-media, etc.) are out of scope for removal; an optional external scorer can only report a SynthID confidence estimate.
• The reverse-SynthID scorer is external, best-effort, and under a non-commercial Research License; it is not bundled and is not an official Google detector.
• C2PA soft binding (content watermark that re-links to a remote manifest after metadata strip) is out of scope — stripping hard-bound C2PA does not clear it.
• Data-driven / backdoor model marks (trigger phrases) are out of scope.

Quick commands cheat sheet

# Unified
python3 "$SCRIPTS/inspect_file.py" notes.md
python3 "$SCRIPTS/clean_file.py" notes.md -o notes.cleaned.md
python3 "$SCRIPTS/clean_file.py" shot.png -o shot.cleaned.png
python3 "$SCRIPTS/clean_file.py" deck.docx -o deck.cleaned.docx

# Text Layer A / B
python3 "$SCRIPTS/inspect_text.py" notes.md
python3 "$SCRIPTS/clean_text.py" notes.md -o notes.cleaned.md --stats
python3 "$SCRIPTS/rewrite_text.py" notes.md --backend print-prompt --strength paraphrase

# Images only
python3 "$SCRIPTS/inspect_image.py" shot.png
python3 "$SCRIPTS/clean_image.py" shot.png -o shot.cleaned.png

Adapted from watermarks-remover. The upstream MIT License and attribution are preserved.