feat(components): make a Y rail's row geometric, with the DOM row as an evidence prior

packages/components/scripts/templates/chat-workspace-geometry-report.html

@@ -331,6 +331,11 @@
         background: var(--candidate-soft);
       }
 
+      .detail-review[data-kind='cross-family-candidate'] .detail-finding {
+        color: var(--text-muted);
+        background: var(--hover);
+      }
+
       .detail-review[data-kind='insufficient'] .detail-finding {
         color: var(--text-muted);
         background: var(--hover);
@@ -585,6 +590,9 @@ <h2>明确排除</h2>
       const reviewCandidates = candidates.filter((d) => d.requiresReview);
       const stableCandidates = candidates.filter((d) => !d.requiresReview);
       const overviews = report.details.filter((d) => d.kind === 'overview');
+      const crossFamilyCandidates = report.details.filter(
+        (d) => d.kind === 'cross-family-candidate'
+      );
       const jitters = report.details.filter((d) => d.kind === 'jitter');
       const insufficient = report.details.filter((d) => d.kind === 'insufficient');
       const measurementModels = report.details.filter((d) => d.kind === 'measurement-model');
@@ -725,6 +733,12 @@ <h2>明确排除</h2>
         ['overview', '整体视图', overviews.length, null],
         ['jitter', '亚像素抖动', jitters.length, 'dot--candidate'],
         ['measurement-model', '测量模型分歧', measurementModels.length, 'dot--candidate'],
+        [
+          'cross-family-candidate',
+          '跨行族候选轨',
+          crossFamilyCandidates.length,
+          'dot--insufficient',
+        ],
         ['insufficient', '证据不足', insufficient.length, 'dot--insufficient'],
         ['stable', '稳定候选轨', stableCandidates.length, 'dot--candidate'],
       ];
@@ -956,13 +970,15 @@ <h2>明确排除</h2>
             ? '候选轨与偏移'
             : detail.kind === 'overview'
               ? '候选轨总览'
-              : detail.kind === 'jitter'
-                ? '亚像素抖动'
-                : detail.kind === 'measurement-model'
-                  ? '测量模型分歧'
-                  : detail.kind === 'insufficient'
-                    ? '证据不足'
-                    : '失败语义线';
+              : detail.kind === 'cross-family-candidate'
+                ? '跨行族候选轨'
+                : detail.kind === 'jitter'
+                  ? '亚像素抖动'
+                  : detail.kind === 'measurement-model'
+                    ? '测量模型分歧'
+                    : detail.kind === 'insufficient'
+                      ? '证据不足'
+                      : '失败语义线';
         const figures = [
           ['原始界面', detail.images.clean, `${detail.title} 原始局部截图`],
           [annotatedLabel, detail.images.annotated, `${detail.title} ${annotatedLabel}局部截图`],

packages/components/src/lib/AGENTS.md

@@ -95,8 +95,14 @@ Production layout stays ordinary Flex/Grid with stable geometry data markers onl
 columns are never props or wrapper DOM. Fixture and gate share one spec. `?geometry=1` adds
 the overlay, alignment lines and spacing diagnostics; dev only.
 
-- Explicit control boxes: repeated slots share an X line across rows, icon/text controls
-  in one row a Y instance.
+- Explicit control boxes: repeated slots share an X line across rows.
+- A Y rail's row is GEOMETRIC: `assignGeometricRows` puts an extent on the line whose MEDIAN
+  band it overlaps by half — to that band, never neighbour to neighbour, or a ladder of
+  half-overlaps chains two lines of different heights into one, as chaining intermediate
+  coordinates would merge two indentation levels. The DOM row is a PRIOR setting the EVIDENCE
+  BAR, never eligibility, which as a gate hid every cross-structural line by construction.
+  An atom no row accepted is measured on Y under its own row id, or the DOM would still gate
+  a layer earlier; alone in that row, it can only reach the cross-family bar.
 - Cross-font rows compare ink centres — a cap-height band from a fixed reference glyph,
   transformed SVG path bounds, a painted CSS shape's box; baselines compare text only
   ([tests/e2e/support](../../tests/e2e/support/AGENTS.md)). The overlay and the capture take