test(M00): add landmark-region visual diff

docs/CAMERA_POSE_SWEEP.md

@@ -54,4 +54,10 @@ A WMO-ready joint grid fixed yaw at 10 degrees and evaluated pitch `[-25, -20, -
 
 The grid therefore has no approved joint optimum. Full-frame color error continues to trade landmark framing against large terrain regions. The manifest remains unchanged. The next registration method must score an approved inn/road/tree landmark region or explicit landmark coordinates rather than the entire image.
 
+## Common landmark region — 2026-07-12
+
+The comparator accepts an optional common screen rectangle through `--region x,y,width,height`; the sweep runner exposes it as `-ComparisonRegion x,y,width,height`. Coordinates are integer pixels in the shared reference/candidate image space. Both images must have identical dimensions and the rectangle must be fully inside them. Omitting the option preserves full-frame behavior.
+
+The existing 15 WMO-ready Goldshire candidates were rescored inside `[300,100,1400,650]`, covering the reference facade/chimney and nearby trees. ROI error ranked FOV 38/yaw 10/pitch -15 first at `0.081777` with changed-pixel ratio `0.697185`. This is an interior pitch candidate and improves on the full-frame grass preference, but human inspection still rejects manifest calibration: the facade is too large, its upper part is cropped, and the rectangle retains substantial road/terrain pixels. A common rectangle is useful diagnostic weighting, not semantic landmark registration. Explicit approved landmark coordinates or a mask remain necessary.
+
 During this run the sweep orchestration was hardened in two ways: expected comparator exit code `1` is now collected through an explicit child process, and viewport dimensions are explicit. A reference/candidate `size_mismatch` now fails before ranking instead of producing an empty metric.

docs/modules/world-renderer.md

@@ -233,6 +233,7 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 - The first Goldshire pose grid was invalidated by WMO readiness: the inn is absent after 2 seconds but visible after the manifest-standard 8-second wait. Pose comparisons must stabilize asynchronous checkpoint content first.
 - A ready-scene Goldshire 3x3 grid improved mean error from `0.101402` at zero offsets to `0.087952` at yaw `10`/pitch `-10`; pitch/FOV refinement remains required before manifest calibration.
 - Joint Goldshire pitch/FOV refinement had no human-approved optimum: full-frame error preferred grass-heavy FOV 62/pitch -25, while FOV 38/pitch -10 better matched building scale. Landmark/region scoring is required before calibration.
+- Common-region scoring `[300,100,1400,650]` moved Goldshire's numeric optimum to FOV 38/yaw 10/pitch -15, but human inspection still found an oversized/cropped facade; semantic landmarks or masks remain required.
 - D3D12 descriptor issues remain; the capture-path anonymous `RefCounted` shutdown leak is regression-covered by a clean verbose dry-run, while other RID/resource diagnostics still require independent evidence.
 - M2/WMO/material/particle/ribbon/portal parity incomplete.
 - Public API is mostly exported configuration rather than stable contracts.