Register RunningHub, Baidu, and LibLibAI visible marks; park Qingyan and MiniMax (measured)

New engines, each calibrated on its TC260 USCC cohort and validated by a
full-corpus sweep (42009 files):
- runninghub: top-left corner (new corner="tl"), faint mid-gray text via
  the new raw-grayscale "gray" detection front-end, anchor-position gate
- baidu: text-run-only template (pill is a bright-blob magnet), load-bearing
  Doubao+Qwen rival margins, corner-extended footprint for the white tag
- liblib: bottom-center (new corner="bc"), Arial silhouette (font is the
  discriminative lever against latin UI text), logo-extended footprint

Qingyan parked (no clean-arm separation at any render/box), MiniMax/Hailuo
parked (1 visible frame, the xinghui rule); silhouettes kept as starting
points.

tests/test_liblib_engine.py

@@ -0,0 +1,114 @@
+"""Tests for the LibLibAI ("LibLibAI" wordmark) visible-watermark engine.
+
+Every tuned constant in ``liblib_engine`` was measured on the 15-frame vendor
+cohort (2026-07-22); these tests pin the load-bearing ones: the bottom-CENTER
+anchor, the strict-only gate, and the match-box footprint (the blob bbox both
+bled into background structure and did not own the triangle logo).
+"""
+
+from __future__ import annotations
+
+import cv2
+import numpy as np
+import pytest
+
+from remove_ai_watermarks import watermark_registry as registry
+from remove_ai_watermarks.liblib_engine import (
+    _ALPHA_HEIGHT_FRAC,
+    _ALPHA_WIDTH_FRAC,
+    LibLibEngine,
+    _alpha_template,
+)
+
+_MARK_FRAC = 0.10  # measured wordmark width, fraction of the frame WIDTH
+
+
+def _compose(w: int, h: int, bg: float = 100.0):
+    """Composite a triangle logo + the LibLibAI wordmark, bottom-center."""
+    img = np.full((h, w, 3), bg, np.float32)
+    at = _alpha_template()
+    gw = int(_MARK_FRAC * w)
+    gh = max(4, int(_MARK_FRAC * (_ALPHA_HEIGHT_FRAC / _ALPHA_WIDTH_FRAC) * w))
+    ax = (w - gw) // 2
+    ay = int(0.94 * h) - gh
+    amap = np.zeros((h, w), np.float32)
+    amap[ay : ay + gh, ax : ax + gw] = cv2.resize(at, (gw, gh))
+    # the triangle logo, its own height to the LEFT of the wordmark
+    lx1 = ax - int(0.3 * gh)
+    lx0 = lx1 - gh
+    cv2.fillPoly(amap, [np.array([(lx0, ay + gh), (lx1, ay + gh), (lx1, ay)])], 1.0)
+    a3 = amap[:, :, None]
+    wm = (a3 * 255.0 + (1 - a3) * img).clip(0, 255).astype(np.uint8)
+    return wm, (ax, ay, gw, gh, lx0)
+
+
+class TestLocate:
+    def test_box_horizontally_centered(self):
+        eng = LibLibEngine()
+        img = np.zeros((2048, 1536, 3), np.uint8)
+        loc = eng.locate(img)
+        assert (1536 - loc.w) // 2 == pytest.approx(loc.x, abs=2)  # corner="bc"
+        assert 2048 - (loc.y + loc.h) > 0  # bottom-anchored
+
+    def test_box_scales_with_width(self):
+        eng = LibLibEngine()
+        narrow = eng.locate(np.zeros((2048, 1024, 3), np.uint8))
+        wide = eng.locate(np.zeros((2048, 2048, 3), np.uint8))
+        assert wide.w == pytest.approx(narrow.w * 2, rel=0.05)
+
+
+class TestConfig:
+    def test_tophat_frontend(self):
+        assert LibLibEngine().config.detect_frontend == "tophat"
+
+    def test_strict_only_no_provenance_relaxation(self):
+        assert LibLibEngine().config.provenance_ncc_factor == 1.0
+
+    def test_gate_above_clean_arm_max(self):
+        # With the Arial silhouette the full-corpus false arm (latin UI text)
+        # tops out at 0.398 while the cohort sits at 0.43-0.59; gate 0.42.
+        assert LibLibEngine().config.detect_ncc_threshold >= 0.42
+
+    def test_small_image_size_floor(self):
+        # The one full-corpus false fire with the final template was a 200x200
+        # icon on a 20px template; the engine refuses small images outright.
+        eng = LibLibEngine()
+        assert not eng.detect(np.full((200, 200, 3), 100, np.uint8)).detected
+        wm, _ = _compose(200, 200)
+        assert not eng.detect(wm).detected  # even a composed mark under the floor
+
+    def test_registry_row(self):
+        mark = registry.get_mark("liblib")
+        assert mark.location == "bottom-center"
+        assert mark.in_auto
+
+
+class TestDetectAndMask:
+    def test_detects_composed_mark(self):
+        eng = LibLibEngine()
+        wm, _ = _compose(1792, 2400)
+        det = eng.detect(wm)
+        assert det.detected, f"composed mark missed (conf={det.confidence:.3f})"
+
+    def test_clean_frame_stays_quiet(self):
+        eng = LibLibEngine()
+        img = np.full((2400, 1792, 3), 100, np.uint8)
+        assert not eng.detect(img).detected
+
+    def test_mask_covers_logo_and_wordmark(self):
+        """The footprint must cover the triangle logo LEFT of the wordmark while
+        staying bounded by the match box vertically (the blob bbox bled into
+        background structure and ate real content, 2026-07-22)."""
+        eng = LibLibEngine()
+        wm, (ax, ay, gw, gh, lx0) = _compose(1792, 2400)
+        mask = eng.footprint_mask(wm)
+        assert mask is not None
+        ys, xs = np.where(mask > 0)
+        assert xs.min() <= lx0 + gh // 2  # covers the logo
+        assert xs.max() >= ax + gw - int(0.05 * gw)  # covers the wordmark's right edge
+        assert ys.min() >= ay - gh  # does not bleed far above the mark
+
+    def test_no_mask_on_clean_frame(self):
+        eng = LibLibEngine()
+        img = np.full((2400, 1792, 3), 100, np.uint8)
+        assert eng.footprint_mask(img) is None