Align watermark content with detector coverage

src/remove_ai_watermarks/microsoft_engine.py

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+"""Microsoft top-right AI-badge detector/localizer.
+
+This engine covers one measured Microsoft output variant: a white pill with dark
+internal shapes in the top-right corner. The evaluated files used both "Made with
+AI" and "AI-Generated" wording. This is narrower than Microsoft's documented
+watermark feature, which can use a Copilot icon or text and can place the mark in
+other positions. A Microsoft provenance signal therefore does not establish that
+this exact visible variant is present.
+
+Detection matches a synthetic pill silhouette (white pill with the sparkle and
+text KNOCKED OUT) against the top-hat blob of the located box: the holes are what
+discriminate this pill from any other bright rounded element in the corner.
+Removal is the shared **localize -> fill**; the glyph-bbox :meth:`footprint_mask`
+covers the whole pill including its text.
+
+The tuned numbers below were remeasured on 2026-08-27 with the registered engine
+and ``scripts/registered_mark_calibrate.py``. The arms were kept distinct: 17
+visually confirmed carriers, 343 Microsoft-provenance files whose visible-mark
+status was not adjudicated, and 1200 non-overlapping no-signal controls:
+
+  * Geometry is single-mode and tight: pill 0.152 x 0.040 of the LONG side
+    (aspect 3.73-3.89 over 720..1536 px), margins ~0.010/0.007 of the same basis. One size
+    mode, so the shared 3-rung ladder is untouched and the locate box simply
+    wraps the pill with NCC slack.
+  * STRICT ONLY (``provenance_ncc_factor`` 1.0): controls max 0.293 / p99
+    0.200; confirmed carriers p50 0.519 / p90 0.578 / max 0.579, with 15/17
+    above the 0.38 gate. Provenance alone does not relax the gate: only 78/343
+    files in that cohort crossed it, and the rest were not visually labeled.
+  * Front-end "binary": the pill is a bold opaque overlay; the tophat blob is
+    solid with dark-text holes, exactly the template's shape.
+"""
+
+# pyright: reportUnusedFunction=false
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any
+
+from remove_ai_watermarks import _text_mark_engine
+from remove_ai_watermarks._text_mark_engine import TextMarkConfig, TextMarkEngine
+
+if TYPE_CHECKING:
+    from numpy.typing import NDArray
+
+# Locate geometry as a fraction of the image LONG side (measured; scale_basis="long":
+# on 1024x1536 portraits the pill tracks the 1536, and a width basis undersized
+# the template until the portrait carriers fell to 0.15-0.32 NCC).
+# The box wraps the measured pill rect (0.152W x 0.040W) with NCC slack; margins
+# sit inside the pill's own ~0.010W-right / ~0.007W-top insets.
+WM_WIDTH_FRAC = 0.170
+WM_HEIGHT_FRAC = 0.055
+MARGIN_RIGHT_FRAC = 0.004
+MARGIN_TOP_FRAC = 0.003
+
+# Glyph appearance: a bright near-white pill (luma ~245), gray-scale (sat < 60).
+MAX_SATURATION = 60
+LOGO_MIN_LUMA = 170
+TOPHAT_DELTA = 10
+
+# Calibrated 2026-08-27: non-overlapping no-signal controls (n=1200) max 0.293 /
+# p99 0.200; visually confirmed carriers (n=17) p50 0.519 / p90 0.578 / max
+# 0.579, with 15/17 above the 0.38 gate. The two misses score 0.249 and 0.315.
+DETECT_MIN_COVERAGE = 0.30  # the pill fills most of its box; content corners do not
+DETECT_NCC_THRESHOLD = 0.38
+
+# Pill silhouette geometry (fraction of width): 0.152W x 0.040W, aspect ~3.78.
+_ALPHA_NATIVE_WIDTH = 335
+_ALPHA_WIDTH_FRAC = 0.152
+_ALPHA_HEIGHT_FRAC = 0.040
+
+_CONFIG = TextMarkConfig(
+    name="Microsoft top-right AI badge",
+    asset_name="microsoft_alpha.png",
+    corner="tr",
+    margin_floor=2,
+    width_frac=WM_WIDTH_FRAC,
+    height_frac=WM_HEIGHT_FRAC,
+    margin_x_frac=MARGIN_RIGHT_FRAC,
+    margin_bottom_frac=MARGIN_TOP_FRAC,
+    max_saturation=MAX_SATURATION,
+    logo_min_luma=LOGO_MIN_LUMA,
+    tophat_delta=TOPHAT_DELTA,
+    morph_open_size=5,
+    detect_min_coverage=DETECT_MIN_COVERAGE,
+    detect_ncc_threshold=DETECT_NCC_THRESHOLD,
+    alpha_width_frac=_ALPHA_WIDTH_FRAC,
+    alpha_height_frac=_ALPHA_HEIGHT_FRAC,
+    min_gw=24,
+    detect_frontend="binary",
+    scale_basis="long",
+    provenance_ncc_factor=1.0,
+)
+
+
+def _alpha_template() -> NDArray[Any] | None:
+    """The bundled Microsoft pill template (float [0,1]), or None."""
+    return _text_mark_engine.load_alpha_template(_CONFIG.asset_name)
+
+
+class MicrosoftEngine(TextMarkEngine):
+    """Detect/localize the measured Microsoft top-right AI badge."""
+
+    def __init__(self) -> None:
+        super().__init__(_CONFIG)