refactor(mobile): consolidate tap-target geometry into one module

apps/mobile/src/components/agents/platform-filter-modal.mounted.test.tsx

@@ -193,6 +193,27 @@ describe('SessionFilterModal', () => {
     );
   });
 
+  it('omits an empty platform section instead of rendering an orphaned label', async () => {
+    // A live list whose rows all have an unknown origin offers no platform
+    // option (`buildLiveFilterOptions` only offers the origins that are
+    // running), so the section must be omitted exactly as PROJECT already is
+    // when it has no rows — otherwise the sheet shows a bare PLATFORM label
+    // with nothing under it (spot defect e4-filter).
+    const { renderer } = await renderModal({
+      platformOptions: [],
+      selectedPlatforms: [],
+      projectOptions: [firstProject],
+    });
+    const labels = renderer.root.findAllByType(Text).map(text => text.props.children);
+    expect(labels).not.toContain(i18n.t('common.platform'));
+    expect(labels).toContain(i18n.t('agentChat.sessionFilter.project'));
+    expect(
+      renderer.root
+        .findAllByProps({ accessibilityRole: 'checkbox' })
+        .map(row => row.findByType(Text).props.children)
+    ).toEqual([firstProject.displayName]);
+  });
+
   it('commits both draft arrays only on Apply and preserves unavailable selections', async () => {
     const selectedPlatforms = ['cli', 'future-platform'];
     const selectedProjects = [firstProject.gitUrl, unavailable];

apps/mobile/src/components/agents/platform-filter-modal.tsx

@@ -212,21 +212,29 @@ export function SessionFilterModal({
           </Text>
           <ScrollView className="shrink" showsVerticalScrollIndicator={false}>
             <View className="gap-4">
-              <View className="gap-1">
-                <Text variant="eyebrow" className="px-3">
-                  {t('common.platform')}
-                </Text>
-                {platforms.map(platform => (
-                  <FilterCheckboxRow
-                    key={platform}
-                    label={platformFilterLabel(platform)}
-                    isChecked={draftPlatforms.includes(platform)}
-                    onPress={() => {
-                      togglePlatform(platform);
-                    }}
-                  />
-                ))}
-              </View>
+              {/* The rows are derived from the live sessions, so a list whose
+                  rows all have an unknown origin (`liveSessionPlatformBucket`
+                  returns null) offers no platform at all and nothing is
+                  selected. Rendering the label then leaves an orphaned section
+                  header above PROJECT (spot defect e4-filter); the section is
+                  omitted exactly as PROJECT already is when it has no rows. */}
+              {platforms.length > 0 && (
+                <View className="gap-1">
+                  <Text variant="eyebrow" className="px-3">
+                    {t('common.platform')}
+                  </Text>
+                  {platforms.map(platform => (
+                    <FilterCheckboxRow
+                      key={platform}
+                      label={platformFilterLabel(platform)}
+                      isChecked={draftPlatforms.includes(platform)}
+                      onPress={() => {
+                        togglePlatform(platform);
+                      }}
+                    />
+                  ))}
+                </View>
+              )}
               {projectGroups.size > 0 && (
                 <View className="gap-1">
                   <Text variant="eyebrow" className="px-3">

apps/mobile/src/components/pr-review/discussion/comment-row.touch-target.test.tsx

@@ -9,7 +9,7 @@ import { describe, expect, it, vi } from 'vitest';
 
 import { CommentRow } from './comment-row';
 import { CommentModerationProvider } from './comment-moderation';
-import { MIN_AUDITED_CONTROL_FRAME_DP } from '@/lib/a11y/touch-target';
+import { MIN_TAP_TARGET_DP } from '@/lib/a11y/tap-target';
 import {
   COMMENT_ACTIONS_FRAME_DP,
   COMMENT_ACTIONS_HIT_SLOP,
@@ -121,7 +121,7 @@ describe('CommentRow overflow touch target', () => {
     expect(overflow.props.className).toContain('items-center');
     expect(overflow.props.className).toContain('justify-center');
     expect(overflow.props.hitSlop).toEqual(COMMENT_ACTIONS_HIT_SLOP);
-    expect(COMMENT_ACTIONS_FRAME_DP).toBeGreaterThanOrEqual(MIN_AUDITED_CONTROL_FRAME_DP);
+    expect(COMMENT_ACTIONS_FRAME_DP).toBeGreaterThanOrEqual(MIN_TAP_TARGET_DP);
     expect(
       COMMENT_ACTIONS_FRAME_DP + COMMENT_ACTIONS_HIT_SLOP.top + COMMENT_ACTIONS_HIT_SLOP.bottom
     ).toBeGreaterThanOrEqual(44);

apps/mobile/src/components/pr-review/discussion/discussion-thread.touch-target.test.tsx

@@ -7,7 +7,7 @@ import { act, TestRenderer } from '@/test/renderer';
 import { describe, expect, it, vi } from 'vitest';
 
 import { DiscussionThread } from './discussion-thread';
-import { COMPACT_CONTROL_FRAME_DP, COMPACT_CONTROL_HIT_SLOP_DP } from '@/lib/a11y/touch-target';
+import { COMPACT_H11_FRAME_DP, COMPACT_H11_HIT_SLOP_DP } from '@/lib/a11y/tap-target';
 import { type ReviewThread } from '@/lib/pr-review/discussion/review-discussion-types';
 
 vi.mock('react-native', () => ({
@@ -102,8 +102,8 @@ describe('DiscussionThread resolve toggle touch target', () => {
     expect(resolveButton.props.className).toContain('h-11 w-11');
     expect(resolveButton.props.className).toContain('items-center');
     expect(resolveButton.props.className).toContain('justify-center');
-    expect(resolveButton.props.hitSlop).toBe(COMPACT_CONTROL_HIT_SLOP_DP);
-    expect(COMPACT_CONTROL_FRAME_DP + 2 * COMPACT_CONTROL_HIT_SLOP_DP).toBeGreaterThanOrEqual(44);
+    expect(resolveButton.props.hitSlop).toBe(COMPACT_H11_HIT_SLOP_DP);
+    expect(COMPACT_H11_FRAME_DP + 2 * COMPACT_H11_HIT_SLOP_DP).toBeGreaterThanOrEqual(44);
 
     // The visible circle keeps its compact 28pt size inside the frame.
     const circle = resolveButton.find(

apps/mobile/src/components/pr-review/discussion/discussion-thread.tsx

@@ -39,7 +39,7 @@ import { ReplyInput } from '@/components/pr-review/discussion/reply-input';
 import { ThreadDiffSnippet } from '@/components/pr-review/discussion/thread-diff-snippet';
 import { Text } from '@/components/ui/text';
 import { i18n } from '@/i18n';
-import { COMPACT_CONTROL_HIT_SLOP_DP } from '@/lib/a11y/touch-target';
+import { COMPACT_H11_HIT_SLOP_DP } from '@/lib/a11y/tap-target';
 import { formatNumber } from '@/lib/format';
 import {
   type ReviewComment,
@@ -359,7 +359,7 @@ function ResolveToggle({ resolved, disabled, onPress }: Readonly<ResolveTogglePr
       // The frame is the tap target the size audit measures (38.5pt on
       // device) and the header row grows to hold it, so the whole frame is
       // hittable; the 3pt slop reaches the 44pt minimum.
-      hitSlop={COMPACT_CONTROL_HIT_SLOP_DP}
+      hitSlop={COMPACT_H11_HIT_SLOP_DP}
       className="h-11 w-11 items-center justify-center active:opacity-70"
     >
       {/* The visible circle stays compact (explicit px, because NativeWind's

apps/mobile/src/lib/a11y/tap-target.test.ts

@@ -9,6 +9,9 @@ import type * as NativeCSSCompiler from 'react-native-css/compiler';
 import {
   COMPACT_CONTROL_BOX_CLASS,
   COMPACT_CONTROL_HIT_SLOP_DP,
+  COMPACT_H11_FRAME_DP,
+  COMPACT_H11_HIT_SLOP_DP,
+  compactControlTargetDp,
   INLINE_LINK_BOX_CLASS,
   INLINE_LINK_CONNECTOR_CLASS,
   INLINE_LINK_FACING_HIT_SLOP_DP,
@@ -83,6 +86,17 @@ describe('shared tap-target geometry', () => {
     );
   });
 
+  it('keeps the measured h-11 frame at or above the audit floor and reaches the design target', () => {
+    // The regression this guards: a control sized to its glyph (or to a
+    // rem-scaled `h-7`, which measures 24.5dp) is reported as too small to tap.
+    expect(COMPACT_H11_FRAME_DP).toBeGreaterThanOrEqual(MIN_TAP_TARGET_DP);
+    expect(COMPACT_H11_HIT_SLOP_DP).toBeGreaterThan(0);
+    expect(compactControlTargetDp()).toBe(
+      tapTargetReachDp(COMPACT_H11_FRAME_DP, COMPACT_H11_HIT_SLOP_DP)
+    );
+    expect(compactControlTargetDp()).toBeGreaterThanOrEqual(TOUCH_TARGET_DP);
+  });
+
   it('carries an inline link from the audit floor to the design target with its slop', () => {
     expect(INLINE_LINK_BOX_CLASS).toContain('min-h-[28px]');
     expect(INLINE_LINK_BOX_CLASS).toContain('min-w-[28px]');

apps/mobile/src/lib/a11y/tap-target.ts

@@ -36,6 +36,32 @@ export const COMPACT_CONTROL_BOX_CLASS = 'h-[32px] w-[32px] items-center justify
  */
 export const COMPACT_CONTROL_HIT_SLOP_DP = 8;
 
+/**
+ * The frame a compact `h-11` control renders, in pt. NativeWind's rem is 14pt
+ * here, so `h-11` (2.75rem) measures 38.5pt on device: above the
+ * {@link MIN_TAP_TARGET_DP} floor a control-size audit accepts, and
+ * {@link COMPACT_H11_HIT_SLOP_DP} per side carries it to
+ * {@link TOUCH_TARGET_DP}. This is the second compact geometry beside
+ * {@link COMPACT_CONTROL_BOX_CLASS}: an `h-11` frame is set by its
+ * surroundings' layout (`discussion-thread.tsx`, `comment-row.tsx`), not by the
+ * icon-button box that 32pt defines. The frames stay literal class strings in
+ * the components (NativeWind reads them at build time); these numbers keep the
+ * arithmetic and its checks in one place. `comment-trailing-controls.ts` holds
+ * the one control whose neighbour bounds its tap area.
+ */
+export const COMPACT_H11_FRAME_DP = 38.5;
+
+/**
+ * Per-side `hitSlop` that lifts {@link COMPACT_H11_FRAME_DP} to
+ * `DESIGN.md:364`'s 44pt minimum: 38.5 + 3 + 3 = 44.5pt.
+ */
+export const COMPACT_H11_HIT_SLOP_DP = 3;
+
+/** Width and height of an `h-11` compact control's tap area, in pt. */
+export function compactControlTargetDp(): number {
+  return tapTargetReachDp(COMPACT_H11_FRAME_DP, COMPACT_H11_HIT_SLOP_DP);
+}
+
 /**
  * The box an inline text link renders. The sign-in legal links sit inside a
  * sentence, so their box is the control-size audit's {@link MIN_TAP_TARGET_DP}

apps/mobile/src/lib/pr-review/comment-trailing-controls.test.ts

@@ -1,6 +1,6 @@
-import { describe, expect, it } from 'vitest';
+import { describe, expect, it, vi } from 'vitest';
 
-import { MIN_AUDITED_CONTROL_FRAME_DP } from '@/lib/a11y/touch-target';
+import { MIN_TAP_TARGET_DP } from '@/lib/a11y/tap-target';
 import {
   COMMENT_ACTIONS_FRAME_DP,
   COMMENT_ACTIONS_HIT_SLOP,
@@ -11,6 +11,8 @@ import {
   FIX_WITH_KILO_VISUAL_DP,
 } from '@/lib/pr-review/comment-trailing-controls';
 
+vi.mock('react-native', () => ({ I18nManager: { isRTL: false } }));
+
 describe('comment trailing controls tap areas', () => {
   it('keeps the pill and the overflow hit areas apart', () => {
     // The regression this guards: the overflow's 8pt left hitleed used to
@@ -22,7 +24,7 @@ describe('comment trailing controls tap areas', () => {
   it('keeps the overflow frame at or above the 28dp the size audit measures', () => {
     // h-7 measured 24.5dp on device (NativeWind's rem is 14pt) and was
     // reported as too small to tap.
-    expect(COMMENT_ACTIONS_FRAME_DP).toBeGreaterThanOrEqual(MIN_AUDITED_CONTROL_FRAME_DP);
+    expect(COMMENT_ACTIONS_FRAME_DP).toBeGreaterThanOrEqual(MIN_TAP_TARGET_DP);
     expect(COMMENT_ACTIONS_VISUAL_DP).toBeLessThan(COMMENT_ACTIONS_FRAME_DP);
   });
 

apps/mobile/src/lib/pr-review/comment-trailing-controls.ts

@@ -12,7 +12,7 @@
 // session, never the moderation sheet. Keeping the arithmetic in one place lets
 // the row's gap and the two tap areas be checked together (vr1, 2026-09-16).
 
-import { COMPACT_CONTROL_FRAME_DP, COMPACT_CONTROL_HIT_SLOP_DP } from '@/lib/a11y/touch-target';
+import { COMPACT_H11_FRAME_DP, COMPACT_H11_HIT_SLOP_DP } from '@/lib/a11y/tap-target';
 
 /**
  * The pill's visual height in pt, read off its classes in
@@ -33,17 +33,17 @@ export const FIX_WITH_KILO_VISUAL_DP = 23;
 export const FIX_WITH_KILO_HIT_SLOP = { top: 11, bottom: 11, left: 2, right: 2 } as const;
 
 /** The overflow's frame: `h-11 w-11` measured on device. */
-export const COMMENT_ACTIONS_FRAME_DP = COMPACT_CONTROL_FRAME_DP;
+export const COMMENT_ACTIONS_FRAME_DP = COMPACT_H11_FRAME_DP;
 
 /** The overflow's visible circle, in explicit dp so rem cannot shrink it. */
 export const COMMENT_ACTIONS_VISUAL_DP = 28;
 
 /** The overflow's hit slop, which lifts its frame to the 44pt minimum. */
 export const COMMENT_ACTIONS_HIT_SLOP = {
-  top: COMPACT_CONTROL_HIT_SLOP_DP,
-  bottom: COMPACT_CONTROL_HIT_SLOP_DP,
-  left: COMPACT_CONTROL_HIT_SLOP_DP,
-  right: COMPACT_CONTROL_HIT_SLOP_DP,
+  top: COMPACT_H11_HIT_SLOP_DP,
+  bottom: COMPACT_H11_HIT_SLOP_DP,
+  left: COMPACT_H11_HIT_SLOP_DP,
+  right: COMPACT_H11_HIT_SLOP_DP,
 } as const;
 
 /** The trailing group's `gap-3` class, in dp: 0.75rem at NativeWind's 14pt rem. */