diff --git a/AGENTS.md b/AGENTS.md
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@@ -56,7 +56,7 @@ Compact map. The full per-module detail (design decisions, tuned thresholds, cal
 - `noai/constants.py` — the single `C2PA_AI_VENDORS` registry (+ `C2PA_SOFT_BINDINGS`) from which `C2PA_ISSUERS` / `SYNTHID_C2PA_ISSUERS` / `C2PA_IDENTITY_AI_ORGS` / `identify._ISSUER_PLATFORM` are all derived. Add a new vendor as one registry entry; never edit the derived dicts and never add inline. A vendor's `asserts_ai=True` flag means its mere presence asserts AI generation even without a `trainedAlgorithmicMedia` digital-source-type (a pure-generator brand with a distinctive issuer/generator string, e.g. **Dreamina** — ByteDance's international Jimeng brand, signed as "Bytedance Pte. Ltd." with a "Dreamina/x.y" claim generator and no source-type); NEVER set it for common-word issuers (Adobe/Google/OpenAI/Microsoft) that appear incidentally in unrelated bytes — those stay source-type-gated in `identify._attribute_platform`.
 - `metadata.py` — `scan_head(path)` is the shared (memoized) input for every C2PA/AIGC/IPTC byte scan; use it instead of `open().read(1MB)` for any new marker scan. Also home to `synthid_source`, `xai_signature`, `iptc_ai_system`, `aigc_label`, `huggingface_job`, `samsung_genai`, and `remove_ai_metadata` (fail-safe `strip_c2pa_boxes`). **A caller that REPORTS an outcome must use `strip_and_verify`, not `remove_ai_metadata` directly** -- the stripper is deliberately fail-safe (a file PIL cannot decode is copied through UNCHANGED rather than crashing), so its return value cannot distinguish a no-op from a real strip. `metadata --remove` and `batch --mode metadata|all` both re-scan the OUTPUT through it and fail loudly; corpus-observed on real Samsung Galaxy S22 C2PA PNGs, where the command printed "stripped" and exited 0 while the output still read as AI (2026-07-19). **`remove_ai_metadata` is the SINGLE metadata stripper** (the legacy PIL-re-encoding `noai/cleaner` was deleted; the diffusion core and the public `noai.remove_ai_metadata` re-export now point here). It strips **losslessly** per container: ISOBMFF (HEIC/AVIF/MP4) blanks tokens / strips boxes in place; **JPEG uses `_strip_jpeg_metadata_lossless`** — a marker-segment walk that drops the AI-bearing APP segments (C2PA APP11; XMP APP1 carrying C2PA, a China-AIGC token, OR an IPTC `digitalSourceType` / 2025.1 AI-disclosure marker; IPTC-IIM APP13) and scrubs AI EXIF tags via piexif, copying the entropy-coded scan verbatim so **the pixels are bit-identical** (no DCT re-encode). **Detection<->removal parity across every marker placement is load-bearing** — anything a scanner flags, the strip must reach, or a re-served file still reads as AI: (a) the APP1-XMP branch of `_jpeg_app_carries_ai` checks the IPTC marker sets too, not only C2PA/AIGC (the Instagram/MidJourney/Meta "Made with AI" `digitalSourceType` lives in XMP, not the APP13 IIM record); (b) a bare `AIGC{...}` / `{"AIGC":{...}}` block in ANY JPEG APP segment — the specific C2PA(APP11)/XMP(APP1)/IPTC(APP13) checks FALL THROUGH to a generic `_is_aigc_exif_value` drop, so a bare AIGC in APP11 (the common real-corpus placement, NOT a C2PA manifest) is caught, not swallowed by the C2PA-only 0xEB branch — plus the same AIGC block in a STANDARD **PNG text chunk** value (e.g. `Description`, which `_is_ai_key` keeps) is dropped on the value; (c) the China TC260 `{"AIGC":{...}}` block in EXIF `UserComment`/`ImageDescription` is scrubbed by `_scrub_ai_exif` (Doubao producer + Tencent service-provider schemas); (d) the Samsung Galaxy AI `PhotoEditor_Re_Edit_Data` trailer past the JPEG EOI is truncated by `_strip_samsung_trailer` (and `samsung_genai` reads the file tail so a multi-MB photo's trailer past the 512 KB quick-scan window is still DETECTED). Pixels stay bit-identical throughout, so a `--strip-metadata` on a q100 removal output does NOT crush it back to q75; PNG/WebP re-saves are pixel-lossless (WebP written at cv2 lossless mode, quality 101 — quality 1-100 is lossy). **The PIL-fallback save format is chosen by the source's CONTENT, not its file extension** (`_sniff_image_format`, and the JPEG-lossless gate is content-gated too): ~2% of real uploads are misnamed (a PNG served as `.jpg` is the common one), and routing on the extension re-encoded a lossless PNG/WebP into a real JPEG — a silent degradation that broke "work with originals" (corpus-measured ~0.9% of files). A **misnamed** lossless source (source-extension format != content) is preserved in its true format; a **correctly-named** source still honors a deliberate output-extension conversion (e.g. `source.png -> output.jpg`). Not yet handled: a 16-bit PNG is downconverted to 8-bit on the PIL re-save (rare; would need a byte-level PNG chunk stripper). Regression: `tests/test_metadata.py::TestHasAiMetadata::test_strip_preserves_lossless_content_with_mismatched_extension`. **`remove_ai_metadata` is fail-safe on an undecodable image:** a truncated/corrupt file (PIL raises `OSError` decoding it; ~0.2% of real uploads) is copied through UNCHANGED rather than crashing a direct library caller (a web worker would 500 on a partial upload), mirroring `strip_c2pa_boxes` — we cannot strip what we cannot parse, but we never raise. Regression: `tests/test_metadata.py::TestHasAiMetadata::test_remove_ai_metadata_failsafe_on_truncated_png`. Regression: `tests/test_metadata.py::TestHasAiMetadata::{test_jpeg_metadata_strip_is_pixel_lossless, test_jpeg_strip_removes_iptc_marker_in_xmp}`, `TestSamsungGenai::{test_remove_strips_post_eoi_trailer, test_detects_trailer_past_scan_window}`, the AIGC-EXIF/bare-APP removal tests, and `tests/test_noai.py::TestISOBMFF::{test_blank_aigc_block_in_exif, test_blank_xai_signature_pair_in_exif}`. `exif_generator` matches a VALUE against `AI_GENERATOR_TOKENS` across EXIF `Software`/`Make`/`Artist`/`ImageDescription`, XMP `CreatorTool`, AND PNG `tEXt` chunks (`Software`/`Source`/`Title`/`Description` — NovelAI stamps there, not EXIF). **Detection and removal must stay in parity:** a generator that stamps an AI-shaped VALUE under a non-AI KEY (NovelAI's `Title`/`Source`) is dropped on removal by `_is_ai_value` (value-token match, mirrors `exif_generator`), NOT by `_is_ai_key` alone — else the cleaned file still reads as that generator. Add a new no-C2PA generator = one `AI_GENERATOR_TOKENS` entry (use a distinctive token, e.g. `reve.com` not bare `reve`); detection and removal then both follow. Regression: `tests/test_metadata.py::TestExifGenerator::{test_novelai_png_text_chunk_detected,test_novelai_removal_parity}`.
 - `identify.py` — aggregates every locally-readable signal into one `ProvenanceReport`; `is_ai_generated` is True or None, never asserted False. `ProvenanceReport.ai_source_kind` exposes the C2PA digital-source-type split — `"generated"` (trainedAlgorithmicMedia, fully AI) vs `"enhanced"` (compositeWithTrainedAlgorithmicMedia, a real photo with an AI-composited region), else None — so a caller branches full-frame scrub vs region-targeted clean (see `noai/tiling.feather_region_composite` + `WatermarkRemover.remove_watermark(region=...)`). The sparkle provenance threshold is the SHARED `watermark_registry.GEMINI_SPARKLE_TRUST_CONF` (imported, not a private copy) so the provenance "is there a sparkle" verdict and the removal "take the sparkle" decision can never drift. `import identify` is deliberately light (lazy `noai/__init__`, fits a 512 MB host) — keep heavy imports out (the `watermark_registry` constant import stays light: engines are lazy there). Add capture-camera tokens to `_DEVICE_C2PA_PLATFORM` only when verified against a real C2PA file; editing-app/AI-device signer tokens go to `_SIGNER_C2PA_PLATFORM`; generator/issuer platforms to `C2PA_AI_VENDORS` in `constants.py`. The IPTC `digitalSourceType` **`algorithmicMedia`** (bare) is PROCEDURAL (an algorithm not trained on sampled data), NOT AI/ML generation, so it is deliberately absent from `IPTC_AI_MARKERS` — flagging it made `identify` assert AI + `has_invisible_target` True, scrubbing clean procedural content (it is a distinct token from `trainedAlgorithmicMedia`, so real "Made with AI" labels are unaffected; regression `test_metadata.py::...test_bare_algorithmic_media_not_flagged_ai`). Integrity-clash detection is high-precision by design (only hard generator stamps feed it, source-grouped independence). `_vendor_of` normalizes ByteDance/Canva/ElevenLabs/Black Forest Labs (as well as OpenAI/Google/... ) so their C2PA claims participate in the clash check; the generic **China TC260 AIGC label names no specific vendor**, so when a TC260-applying vendor (ByteDance, `_TC260_VENDORS`) is co-attributed the label is attributed to it (a legit Doubao image carrying its own TC260 label must NOT clash), while a NON-TC260 vendor next to a TC260 label still clashes as a laundering tell. Corpus-validated: adding the vendors introduced 0 new clashes on 5000 carriers.
-- `watermark_registry.py` — the single catalog of known visible watermarks (gemini / doubao / jimeng / samsung / jimeng_pill). **Removal is LOCALIZE -> FILL for every mark:** each mark is localized to a binary full-frame footprint mask (a `Localization`), then ONE shared, swappable fill inpaints that mask via `fill(image, mask, backend=...)` (delegates to `region_eraser.erase`). Reverse-alpha (the old `original = (wm - a*logo)/(1-a)` inversion of a captured alpha map + thin residual inpaint) is GONE for ALL marks; why it was dropped is recorded in `docs/module-internals.md`. Backends: `cv2` (classical inpaint, no deps, the floor), `migan` (MI-GAN ONNX, light, the memory-tight pick where LaMa will not fit), `lama` (big-LaMa ONNX, best quality, heavier, auto-preferred when a learned backend is available); `auto` = LaMa > MI-GAN > cv2, best available. The captured alpha maps (`scripts/visible_alpha_solve.py`) are still used to DETECT the marks and to shape the mask, but NOT for pixel recovery. **`--mark auto` removes EVERY detected mark in one pass** via `remove_auto_marks(image, *, sensitivity="auto", provenance=frozenset(), backend="auto")` (marks coexist -- a Jimeng-basic image has the top-left pill AND the bottom-right wordmark; a single-strongest pick would leave one). **Three orthogonal axes:** `backend` (the fill), `sensitivity` (how hard to trust a borderline mark: `auto`/`strict`, see the `Sensitivity` literal), and `provenance` (vendor keys metadata confirms -- the evidence that drives `auto`). **Perception / decision / action are separated:** `_build_candidates(image)` runs every detector at BOTH trust levels (strict + relaxed) and packages raw verdicts + features into `Candidate`s (no policy); the pure arbiter `decide(candidates, Context(sensitivity, provenance)) -> [Decision]` makes every keep/drop call (per-mark `resolve_trust` + the assumed-trust floor + the pill gate) with no image/IO, so it is unit-testable in isolation; then each winner is localized -> filled. Do NOT put policy back into the engines (the one exception, the Gemini FP gate, stays in `gemini_engine` because `identify` shares that confidence). `detect_marks(..., provenance=frozenset())` stays strict (identify verdict, precision over recall); `KnownMark.remove/detect/localize(..., provenance: bool)` take the already-resolved boolean. **How `auto` decides (this is metadata-INDEPENDENT for recall):** the visual detectors are pixel-based and need no metadata; the recall gain comes from RELAXING the false-positive gate, not from metadata. `strict` never relaxes (clean images untouched); `auto` relaxes a mark only on same-product evidence -- metadata provenance for that vendor OR a confidently detected sibling mark of the SAME product (`_PRODUCT_OF`; Doubao and Jimeng are both bottom-right ByteDance but distinct products, so they do NOT cross-relax). **`resolve_trust` resolves TWO levels:** `confirmed` bypasses the engine's false-positive gate, and only `confirmed` has evidence naming THAT vendor, which is exactly what the bypass is contracted to require (`GeminiEngine.detect_watermark`'s `trust_provenance` docstring: "external metadata already proves this is a Google generation"). **Historical, kept as the reason the third level is gone:** a removed `assumed` level let `assume_ai` bypass the gate on the bare assertion an image is AI. On its first form that left only the raw 0.35 detector threshold and it fired on **59.8% of 256 genuine camera captures**, filling a phantom sparkle on ~6 of every 10 CLEAN photos; a confidence floor made it tolerable, and the mode was removed outright in 0.16. Corpus-measured 2026-07-16 before removal (400 Google-C2PA positives with metadata hidden; 256 camera-capture negatives): recall strict 55.0% / auto 55.2% / assume_ai 62.8%, false fire 0.0% / 0.0% / 2.3% -- the extra recall was never free. A wrong relaxation only fills a small corner near-losslessly (the localize -> fill benign failure mode), which is what made a SMALL false-fire rate arguable; it was never a licence for a 60% one. Metadata provenance mapping (feeds `auto`, read by `cli._visible_provenance`): Google/Gemini C2PA issuer -> gemini; China-AIGC (TC260) label -> doubao/jimeng; `samsung_genai` -> samsung. **The `jimeng_pill` is CAPTURE-LESS** (`pill_engine.py`): the top-left "AI生成" label has no captured alpha map, so it is detect-by-synthetic-silhouette; its footprint is a fixed top-left geometry box. Its weak edge-NCC detector (~7% raw false-fire) is gated in `remove_auto_marks` via **`_keep_pill`** (32k real-upload corpus validation 2026-07): the pill never rides on a **Doubao** detection, and has confirmation arms because metadata/intent confirms the platform, not pill presence. **(1) Bottom-right "★ 即梦AI" wordmark fired** — ~94% precise and survives **metadata-STRIPPED uploads** (screenshots / re-saves, ~61% of pills carry a detectable wordmark): remove **unrestricted**. **(2) TC260 metadata confirms Jimeng** (`"jimeng" in provenance`, no wordmark) — the metadata-only arm is only ~27% precise and its false fires are **textured ceilings/walls that the fill visibly SMEARS**, so remove **only when the top-left footprint is flat enough for an invisible fill** (`pill_engine.footprint_is_flat`, median-Sobel texture ≤ `_FLAT_TEXTURE_MAX`) — the flatness guard always holds. This keeps real flat-scene pills (incl. metadata-only ones the wordmark misses) plus harmless flat false fires, and leaves the damaging textured false fires untouched. Do NOT drop the wordmark arm or loosen the flatness guard. `cli._write_bgr_with_alpha` must NOT zero alpha in the watermark bbox (issue #30 white-box regression). **The localizer is cheap CPU (cv2/numpy), so a memory-tight caller runs it anywhere; the heavy MI-GAN/LaMa fill is opt-in and chosen by the caller** (a small worker can use cv2; a GPU/model worker can use MI-GAN/LaMa). Adding a new mark needs only a DETECTION silhouette (removal is template-free — the glyph-blob bbox is filled, no capture involved). Produce that silhouette SYNTHETICALLY: font-render the mark's glyphs (the pill's `scripts/render_pill_silhouette.py` is the pattern; commit the rendered PNG under `assets/`) and calibrate the NCC threshold on real positives. The old solid/gray/white app-capture workflow (`scripts/visible_alpha_solve.py`) is RETIRED with reverse-alpha — existing marks still carry their captured silhouettes, but a NEW mark does NOT require captures. (The 2026-06-22 "synthetic reconstruction below the quality bar" objection was about reverse-alpha PIXEL recovery, which is gone; it does not apply to a synthetic detection silhouette.) Data-safety still binds the committed asset: the silhouette must be font-rendered synthetic, never derived from user uploads — seeing a real sample to learn the glyphs / font / position / locale is fine, but the committed template stays synthetic. So nothing is parked for lack of a capture: Meta AI and more Samsung locales just need the glyphs + font + locale + calibration positives; any Grok visible mark additionally needs confirming it even HAS one (its known signal is EXIF-only `xai_signature`).
+- `watermark_registry.py` — the single catalog of known visible watermarks (gemini / doubao / jimeng / samsung / jimeng_pill). **Removal is LOCALIZE -> FILL for every mark:** each mark is localized to a binary full-frame footprint mask (a `Localization`), then ONE shared, swappable fill inpaints that mask via `fill(image, mask, backend=...)` (delegates to `region_eraser.erase`). Reverse-alpha (the old `original = (wm - a*logo)/(1-a)` inversion of a captured alpha map + thin residual inpaint) is GONE for ALL marks; why it was dropped is recorded in `docs/module-internals.md`. Backends: `cv2` (classical inpaint, no deps, the floor), `migan` (MI-GAN ONNX, light, the memory-tight pick where LaMa will not fit), `lama` (big-LaMa ONNX, best quality, heavier, auto-preferred when a learned backend is available); `auto` = LaMa > MI-GAN > cv2, best available. The captured alpha maps (`scripts/visible_alpha_solve.py`) are still used to DETECT the marks and to shape the mask, but NOT for pixel recovery. **`--mark auto` removes EVERY detected mark in one pass** via `remove_auto_marks(image, *, sensitivity="auto", provenance=frozenset(), backend="auto")` (marks coexist -- a Jimeng-basic image has the top-left pill AND the bottom-right wordmark; a single-strongest pick would leave one). **Three orthogonal axes:** `backend` (the fill), `sensitivity` (how hard to trust a borderline mark: `auto`/`strict`, see the `Sensitivity` literal), and `provenance` (vendor keys metadata confirms -- the evidence that drives `auto`). **Perception / decision / action are separated:** `_build_candidates(image)` runs every detector at BOTH trust levels (strict + relaxed) and packages raw verdicts + features into `Candidate`s (no policy); the pure arbiter `decide(candidates, Context(sensitivity, provenance)) -> [Decision]` makes every keep/drop call (per-mark `resolve_trust` + the assumed-trust floor + the pill gate) with no image/IO, so it is unit-testable in isolation; then each winner is localized -> filled. Do NOT put policy back into the engines (the one exception, the Gemini FP gate, stays in `gemini_engine` because `identify` shares that confidence). `detect_marks(..., provenance=frozenset())` stays strict (identify verdict, precision over recall); `KnownMark.remove/detect/localize(..., provenance: bool)` take the already-resolved boolean. **How `auto` decides (this is metadata-INDEPENDENT for recall):** the visual detectors are pixel-based and need no metadata; the recall gain comes from RELAXING the false-positive gate, not from metadata. `strict` never relaxes (clean images untouched); `auto` relaxes a mark only on same-product evidence -- metadata provenance for that vendor OR a confidently detected sibling mark of the SAME product (`_PRODUCT_OF`; Doubao and Jimeng are both bottom-right ByteDance but distinct products, so they do NOT cross-relax). **`resolve_trust` resolves TWO levels:** `confirmed` bypasses the engine's false-positive gate, and only `confirmed` has evidence naming THAT vendor, which is exactly what the bypass is contracted to require (`GeminiEngine.detect_watermark`'s `trust_provenance` docstring: "external metadata already proves this is a Google generation"). **Historical, kept as the reason the third level is gone:** a removed `assumed` level let `assume_ai` bypass the gate on the bare assertion an image is AI. On its first form that left only the raw 0.35 detector threshold and it fired on **59.8% of 256 genuine camera captures**, filling a phantom sparkle on ~6 of every 10 CLEAN photos; a confidence floor made it tolerable, and the mode was removed outright in 0.16. Corpus-measured 2026-07-16 before removal (400 Google-C2PA positives with metadata hidden; 256 camera-capture negatives): recall strict 55.0% / auto 55.2% / assume_ai 62.8%, false fire 0.0% / 0.0% / 2.3% -- the extra recall was never free. A wrong relaxation only fills a small corner near-losslessly (the localize -> fill benign failure mode), which is what made a SMALL false-fire rate arguable; it was never a licence for a 60% one. Metadata provenance mapping (feeds `auto`, read by `cli._visible_provenance`): Google/Gemini C2PA issuer -> gemini; China-AIGC (TC260) label -> doubao/jimeng; `samsung_genai` -> samsung. **The `jimeng_pill` is CAPTURE-LESS** (`pill_engine.py`): the top-left "AI生成" label has no captured alpha map, so it is detect-by-synthetic-silhouette; its footprint is a fixed top-left geometry box. Its weak edge-NCC detector (~7% raw false-fire) is gated in `remove_auto_marks` via **`_keep_pill`** (32k real-upload corpus validation 2026-07): the pill never rides on a **Doubao** detection, and has confirmation arms because metadata/intent confirms the platform, not pill presence. **(1) Bottom-right "★ 即梦AI" wordmark fired** — ~94% precise and survives **metadata-STRIPPED uploads** (screenshots / re-saves, ~61% of pills carry a detectable wordmark): remove **unrestricted**. **(2) TC260 metadata confirms Jimeng** (`"jimeng" in provenance`, no wordmark) — the metadata-only arm is only **21% precise raw (CI 16-29%), 29% (CI 20-40%) among the flat footprints the guard PASSES** (re-measured 2026-07-18, 149 blind-labelled fires) and its false fires are **textured ceilings/walls that the fill visibly SMEARS**, so remove **only when the top-left footprint is flat enough for an invisible fill** (`pill_engine.footprint_is_flat`, median-Sobel texture ≤ `_FLAT_TEXTURE_MAX`) — the flatness guard always holds. This keeps real flat-scene pills (incl. metadata-only ones the wordmark misses) plus harmless flat false fires, and leaves the damaging textured false fires untouched. Do NOT drop the wordmark arm or loosen the flatness guard. **`assume_ai` was REMOVED (2026-07-19); `--sensitivity` is now `auto`/`strict` only.** It relaxed every mark's FP gate on the bare assertion an image is AI -- which names no vendor and no location, exactly what the bypass requires -- and had no place in the model (detector finds -> remove; finds nothing -> leave alone; user SEES a mark -> act on that). It took `_ASSUMED_CONF_FLOOR` / `assumed_floor_ok` / the `assumed` trust level with it, collapsing the ladder to `strict`/`confirmed`, and `_keep_pill` lost its `sensitivity` arg. Recall/precision on the unbiased sample are unchanged, so nothing on the default path moved. **Replacement advice is per mark:** `erase --region` is sound by construction; `--mark <text-mark> --no-detect` is reasonable (forced mask = the real glyph blob, non-empty 13/13); **`--mark gemini --no-detect` is NOT** -- it falls back to a fixed slot that covered the true sparkle on only **31% of 97** missed sparkles, so 69% fill a clean corner AND report a removal that did not happen. `cli._no_visible_mark_exit` follows that order and no longer suggests the removed mode. Migration raises loudly (`validate_sensitivity`, called from `api.remove_visible` and `Context.__post_init__`) because a `Literal` is unenforced at runtime and would silently downgrade a 0.15 caller to `auto`. **Detection can skip binarization** (`TextMarkConfig.detect_frontend`): `binary` thresholds the top-hat into a glyph blob (the original path), `tophat` correlates the CONTINUOUS top-hat against a soft template, turning the saturation/luma gates into weights and max-normalizing so the score is contrast-invariant. **Doubao uses `tophat`** (recall 89% -> 92% at an unchanged 99% precision on the unbiased sample); jimeng/samsung stay `binary` until measured per mark. **Detection and the REMOVAL MASK must use the SAME front-end.** `tophat` detection does not binarize, but `extract_mask` (which bounds the fill) still does, so a mark faint enough to be found only by the continuous response produced an EMPTY mask: `localize` returned None, `remove()` was a silent no-op, and `identify` reported `visible_doubao` while `visible` said "no visible mark" on the same file. Corpus-measured 2026-07-20: 57 of 60 sampled still-detected Doubao marks were untouched, ~8% of all its detections. `footprint_mask` now falls back to thresholding the CONTINUOUS response at `_FAINT_GLYPH_LEVEL` when the binary blob is empty -- **gated on an actual detection**, because the response is max-normalized and would otherwise scale NOISE up to 1.0 and mask a random patch of a clean corner. Verified on the corpus: 60/60 previously-untouched cases now clear. Regression: `tests/test_text_mark_faint_mask.py`. **Any future front-end change must move BOTH paths or re-check this.** **The gate is front-end specific -- re-calibrate, never port it**: the continuous response scores higher (mean 0.809 vs 0.723), so the binary-era 0.40 ran 96%/91% (8 false fires) while 0.50 runs 92%/99% (1). A first pass at 0.40 also silently halved the PILL's recall, since `_keep_pill` suppresses it whenever doubao fires. The front-end fixes DETECTION of faint marks but not ATTRIBUTION: 千问 becomes separable from clean corners (AUC 0.92) yet not from Doubao (**AUC ~0.5**) because they share the `AI生成` tail. Next design is a GENERIC CJK-AI-mark detector (GB 45438-2025 guarantees the shared tail) with vendor attribution as optional metadata. **Adding a new text mark is only cheap when the mark is stamped BOLD** -- 千问/星绘 are deliberately NOT registered. Measured on 14 corpus positives with the same pipeline and each mark's own template: doubao mean NCC **0.723** (82% over the 0.40 gate) vs qwen **0.170** (**0%**). Ruled out by measurement, in order: the synthetic render (a template cut from a REAL Qwen mark scores 0.307 vs the rendered 0.308, and real masks do not match each other), the fixed 5px morphology kernels (+0.014 mean when scaled with box height), and the appearance thresholds (best sweep: mean 0.35, 4/14 over the gate). The blocker is SEGMENTATION on a faint mark: the white top-hat shatters a thin translucent overlay into specks, and no template matches a blob that is not there. Adding it needs a front-end that does not binarize the glyph first (grayscale/edge correlation on the raw top-hat, or a learned patch classifier). **Check a candidate mark's contrast before promising it is a config-plus-silhouette job.** Evidence chain in `scripts/render_vendor_silhouettes.py`. **RECALL is measured on an unbiased random sample** (`scripts/visible_recall_sample.py`; 240 images drawn at random per provenance class and labelled exhaustively, 2026-07-18): doubao **89% recall / 99% precision**, gemini **96% / 80%**, jimeng 71%/71% (n=14), jimeng_pill 50%/60% (n=6). The `scale_basis` fix moved doubao recall **71% -> 89%** on this same sample. **Gemini's real precision is 80%, NOT the 41% `visible_eval.py` reports** -- that harness scores an addition-sampled set, so it measures the relaxation arm's marginal cases, not what production sees; quote 80% for the product. Landscape is improved but unsolved (doubao by aspect: portrait 92% / square 92% / landscape 79%). The largest remaining gap is not tuning but COVERAGE: **6% of sampled images carry an uncovered vendor's mark** (千问/百度/星绘/抖音-class) that no registered detector can fire on -- researched specs are in `docs/watermarking-landscape.md`. **Mark geometry scales with a PER-MARK dimension** (`TextMarkConfig.scale_basis` / `TextMarkEngine.scale_base`): doubao `short` (= min(h,w)), jimeng and samsung `width`. All the tuned fractions were calibrated on PORTRAIT captures where width == short side, so the basis went unexercised until landscape inputs were measured -- and **doubao detected 0 of 435 landscape TC260 images, a 100% miss rate**. It is a LOCALIZATION failure, not a threshold one (median doubao NCC on the 1452 no-detection images was 0.057, only 2.7% in a threshold-reachable band), so no amount of gate tuning could reach it. Short-side geometry recovers **56% of the previously-undetected landscape set**. The basis is per-mark because the SAME switch took jimeng's landscape positives from 13/13 to 0/13 -- its wordmark tracks the width even though both marks are ByteDance and share a corner; samsung stays `width` because it is unmeasured (1 addition corpus-wide). GB 45438-2025 5.2(e) mandates glyph height >= 5% of the shortest side, which is why short-side is the prior -- but measurement overrides the standard's wording. This was invisible for months because **precision was measured repeatedly and recall never was**; the harness now reports a `missed` column, which is what caught the jimeng regression the fix introduced. **Detection among same-corner marks is COMPETITIVE** (`TextMarkConfig.rivals` / `_rival_margin_ok`): a mark's template must beat every same-corner rival's on the SAME glyph blob by `rival_margin` (0.10). Absolute-only scoring could never separate Doubao and Jimeng (both bottom-right near-white CJK, near-identical after binarization) -- measured separability: absolute `ncc_jimeng` 0.96, `ncc_jimeng` MINUS `ncc_doubao` **0.99**. Corpus effect: **jimeng precision 38% -> 63% with genuine detections unchanged (false fires 65 -> 23)**, so it is a pure precision gain and the earlier 0.85 threshold patch was reverted to 0.70. **Asymmetric by measurement:** doubao declares NO rival -- the symmetric gate cost it 7 genuine detections to prevent 5 false (1.4:1 against) while jimeng gained 25pp for free. **Benchmark any detector change with `uv run python scripts/visible_eval.py --vs <snapshot>`** (741 blind-labelled corpus images; `scripts/visible_groundtruth.py` builds the set, `scripts/visible_sheets.py` makes new labelling rounds). Three harness rules are load-bearing: score a mark only within its crop's **adjudication scope**, take **provenance from metadata not from labels** (label-derived provenance scored gemini at 99% vs the true 41%), and **never report recall** from this set -- it was sampled where detectors fired, so an unbiased random sample is still needed. **The provenance NCC relaxation is PER MARK (`TextMarkConfig.provenance_ncc_factor`), not one shared multiplier** — measured 2026-07-18 on the default `auto` path over 4417 unique TC260 carriers (blind hand-label, two-sided control, labeller sensitivity 100%/96% and specificity 100%/100%), the old shared 0.7 ran at **76% precision on doubao but 17% on jimeng**. Doubao stays 0.70 (both its bands return more true marks than false fills). Jimeng moves to **0.85**: its relaxed silhouette keys on "text in the bottom-right corner" rather than the wordmark — of 68 false additions **33 were DOUBAO marks** and 17 were other vendors' AI labels, and 45 of the 68 filled a corner nothing else would touch; 0.85 costs 8 genuine recoveries to prevent 60 false fills (7.5:1), lifting the arm to 43%. That is a patch on a DETECTOR problem — jimeng's silhouette is not discriminative against doubao's, and no threshold fixes that. **A weak mark must not CORROBORATE a sibling** (`_CANNOT_CORROBORATE`): sibling corroboration grants `confirmed` trust, which bypasses the sibling's FP gate, so the pill (~7% raw false-fire) handing that bypass to jimeng created a closed loop on the DEFAULT path — pill false-fires → jimeng relaxes and false-fires → `_keep_pill`'s wordmark arm then removes the pill UNRESTRICTED, skipping the flatness guard (3/578 negatives ran the full loop, one with `footprint_flat=0`). Cutting the pill out of corroboration removed all 3 and cost NOTHING on the TC260 carriers (jimeng 398 → 398). `_keep_pill` already distrusted the pill's ACTION; this closes the gap that its TESTIMONY was ungated. `cli._write_bgr_with_alpha` must NOT zero alpha in the watermark bbox (issue #30 white-box regression). **The localizer is cheap CPU (cv2/numpy), so a memory-tight caller runs it anywhere; the heavy MI-GAN/LaMa fill is opt-in and chosen by the caller** (a small worker can use cv2; a GPU/model worker can use MI-GAN/LaMa). Adding a new mark needs only a DETECTION silhouette (removal is template-free — the glyph-blob bbox is filled, no capture involved). Produce that silhouette SYNTHETICALLY: font-render the mark's glyphs (the pill's `scripts/render_pill_silhouette.py` is the pattern; commit the rendered PNG under `assets/`) and calibrate the NCC threshold on real positives. The old solid/gray/white app-capture workflow (`scripts/visible_alpha_solve.py`) is RETIRED with reverse-alpha — existing marks still carry their captured silhouettes, but a NEW mark does NOT require captures. (The 2026-06-22 "synthetic reconstruction below the quality bar" objection was about reverse-alpha PIXEL recovery, which is gone; it does not apply to a synthetic detection silhouette.) Data-safety still binds the committed asset: the silhouette must be font-rendered synthetic, never derived from user uploads — seeing a real sample to learn the glyphs / font / position / locale is fine, but the committed template stays synthetic. So nothing is parked for lack of a capture: Meta AI and more Samsung locales just need the glyphs + font + locale + calibration positives; any Grok visible mark additionally needs confirming it even HAS one (its known signal is EXIF-only `xai_signature`).
 - `gemini_engine.py` — visible Gemini-sparkle detector + localizer (cv2/numpy, no GPU): top-K size-weighted fusion candidate selection (`_SELECT_TOPK`), corner-promote, false-positive gate (the provenance prior relaxes the gate + lowers the trust threshold when a Google/Gemini C2PA issuer confirms the vendor). **White-core rescue:** the FP gate demotes a low-gradient match (soft edges), but a real FAINT sparkle also has soft edges -- so the gate keeps a low-grad match that is a strong (conf ≥ `_SPARKLE_KEEP_CONF` 0.52), bright (margin), near-WHITE-core sparkle (`_core_saturation` ≤ `_SPARKLE_WHITE_SAT` 0.20): a real sparkle core is white, a clean bright corner that shape-matches (sky/sun) is colored. This recovers ~14/20 metadata-stripped faint sparkles under the DEFAULT strict/auto (no flag, no metadata) at ~1.25% clean false-fire (baseline 0.55%); the ~0.51-scoring bright-bg FPs stay demoted (below 0.52). A learned classifier on the SAME features was measured WORSE than the tuned gate (2026-07 tier-1: MLP 86.7% recall vs 90.8% at equal FP), so the heuristic stays; a patch-CNN with richer features is the only lever left (roadmapped P2, low expected value -- the wall is fundamental). Detection scores the top-K size-weighted matches by full fusion (spatial+gradient+variance) and keeps the highest — NOT the raw-NCC argmax, which re-admits the tiny-patch FPs the size weight suppresses (the osachub 2026-06-12 sub-0.85 corner-sparkle regression; see `docs/module-internals.md`). Keep the 0.85 corner-promote NCC gate; a margin/chroma-gated lower promote was measured and REJECTED 2026-06-11 (~33% FP on non-Google content). Removal is localize -> fill: `footprint_mask` returns the sparkle footprint (the captured alpha thresholded LOW so the faint halo is included, then dilated by a sparkle-relative margin), and the shared `watermark_registry.fill` inpaints it. The captured alpha maps are used only to detect and to shape the mask, not for pixel recovery. `detect_sparkle_confidence` reuses a process-wide `_shared_engine()` singleton (lru_cache) — the engine holds only constant assets (captures, alpha maps, a precomputed 16..118 template ladder) and takes the image as an arg, so do NOT reconstruct `GeminiEngine()` per call: that reloaded assets + recomputed alpha maps + rebuilt the template cache on every one of ~34k `identify` calls (−24% on the sparkle path once made a singleton, output byte-identical). `detect_watermark`/`footprint_mask` guard `image.size == 0` before `to_bgr`, and return an empty (detected=False) result when no template scale fits (short side < 16 px), rather than dereferencing an empty candidate list.
 - `_text_mark_engine.py` — shared base for the three text-mark engines (extracted 2026-06-09); the per-engine modules are config-only subclasses. Detection still matches the glyph silhouette (NCC, keys on glyph shape). The removal mask is TEMPLATE-FREE: it is the bounding box of the top-hat glyph blob (`extract_mask`), filled solid + dilated, so the shared fill inpaints the whole wordmark rectangle. This drops the fixed alpha-template placement, so a re-rendered or differently-placed mark is still masked; the captured alpha maps are now used only for the detection silhouette, not for removal. New text mark = a `TextMarkConfig` + a thin subclass + one registry row. Gemini stays a separate engine (different model).
 - `pill_engine.py` — the CAPTURE-LESS Jimeng-basic "AI生成" pill (top-left, issue #54). No alpha map: `detect` is edge-NCC of a synthetic font-rendered silhouette (`assets/jimeng_pill.png`, regenerate via `scripts/render_pill_silhouette.py`; committed, data-safe -- corpus stays out of the repo) in the top-left ROI, calibrated on 61 local real positives to threshold 0.22; `footprint_mask` is a generous FIXED top-left geometry box (NOT the NCC match position -- the synthetic silhouette localizes only approximately, the corner is negative space, so a geometry box fills cleanly while a match box leaves outline residue). `footprint_texture`/`footprint_is_flat` (median-Sobel over that box, `_FLAT_TEXTURE_MAX`) back the metadata-only safe-fill gate. Removal is the shared localize -> fill (MI-GAN/cv2). Detector precision is weak (~7% raw false-fire), so it is registry-gated in `remove_auto_marks` via `_keep_pill`: never on Doubao; the bottom-right wordmark removes it unrestricted (~94% precise, survives metadata-STRIPPED uploads); TC260-metadata-only removes it ONLY on a flat footprint (its textured false fires -- ceilings/walls -- are what the fill smears). Do NOT loosen those gates.