[saphid]

What Changed

Programmatic scrolling now reads the current reduced-motion preference when the action runs. Theme token reveal, timeline minimap and send anchors, scroll-to-bottom, keyboard page steps, tabs, settings navigation and citation reveal share the web behavior; native message-to-end actions query the device preference. Missing or unavailable preference APIs select instant movement.

Scroll destinations, focus, selection, direct manipulation, held scrolling and keyboard dismissal retain their existing behavior. The contribution includes the cross-entry-point guidance in #12660, whose documentation commit is still part of this branch.

Verification

• 43 focused web tests passed across ThemeEditorPanel, settingsLayout, pageScrollController and AssistantCitationSource. The unavailable-preference regressions fail five cases with the original helper and pass after the repair.
• Web and mobile package typechecks and scoped lint/format passed. Independent GPT-6.1 Sol review found no actionable source findings and independently reran the 43 web tests.
• Checks used the integrated 38969148 toolchain. A prospective merge onto main 35be904f is clean and preserves the exact contribution; that newer Vite toolchain was not tested here.
• Current integrated web/Electron and native before-and-after motion proof remains missing, including live preference changes and mobile keyboard/scroll timing. Source and unit checks do not prove native animation behavior. This is not yet a merge-ready claim.

Historical evidence from September 20 below predates the current repair and integration. It used an isolated proof app with matchMedia stubbed to reduced motion, comparing base d6f291303 with the then-current branch. It demonstrates that earlier PageDown scenario only; it does not verify the current revision or a native client.

• Historical before
• Historical after
• Historical context

Implementation and readiness repair: GPT-6 Astra using Codex in T3 Code. Independent review: GPT-6.1 Sol using Codex in T3 Code.

[macroscopeapp]

Approvability

Verdict: Approved at d92242b

Macroscope's review found this PR approvable — This is a focused reduced-motion accessibility fix that preserves existing destinations and interaction behavior while removing unnecessary animated travel across established web and mobile scroll paths. The production logic is small and supported by targeted preference and fallback tests, with the larger diff primarily consisting of tests and documentation.

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📥 Commits

Reviewing files that changed from the base of the PR and between d71e51a and d92242b.

📒 Files selected for processing (11)

• apps/mobile/src/features/threads/ThreadDetailScreen.tsx
• apps/web/src/components/ChatView.tsx
• apps/web/src/components/RightPanelTabs.tsx
• apps/web/src/components/chat/AssistantCitationSource.test.ts
• apps/web/src/components/chat/MessagesTimeline.tsx
• apps/web/src/components/chat/pageScrollController.test.ts
• apps/web/src/components/settings/ThemeEditorPanel.test.tsx
• apps/web/src/components/settings/settingsLayout.test.tsx
• apps/web/src/components/settings/settingsLayout.tsx
• apps/web/src/lib/reducedMotion.ts
• docs/internals/consistency-reduced-motion.md

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📝 Walkthrough

Walkthrough

Web and mobile scrolling and reveal actions now account for reduced-motion preferences. The web changes use a shared preference helper, including a fallback for unavailable browser APIs. Mobile thread scrolling checks the device accessibility preference.

Changes

Reduced-motion behavior

Layer / File(s)	Summary
Preference helper and page scrolling apps/web/src/lib/reducedMotion.ts, apps/web/src/components/chat/pageScrollController.ts, apps/web/src/components/chat/pageScrollController.test.ts, docs/internals/consistency-reduced-motion.md	Adds shared reduced-motion detection and immediate page scrolling when enabled. Tests cover unavailable browser APIs and preference changes. The documentation describes reduced-motion constraints across clients.
Chat and panel scrolling apps/web/src/components/ChatView.tsx, apps/web/src/components/RightPanelTabs.tsx, apps/web/src/components/chat/AssistantCitationSource.tsx, apps/web/src/components/chat/AssistantCitationSource.test.ts, apps/web/src/components/chat/MessagesTimeline.tsx	Uses the shared preference reader to select animated or immediate scrolling in chat and panel actions. Citation tests cover reduced motion and unavailable browser preference APIs.
Settings reveal scrolling apps/web/src/components/settings/ThemeEditorPanel.tsx, apps/web/src/components/settings/ThemeEditorPanel.test.tsx, apps/web/src/components/settings/settingsLayout.tsx, apps/web/src/components/settings/settingsLayout.test.tsx	Uses the reduced-motion preference for theme and settings target reveals. Tests cover preference changes and missing matchMedia.
Mobile thread scrolling apps/mobile/src/features/threads/ThreadDetailScreen.tsx	Checks the device accessibility preference for submitted-message and manual scroll-to-end actions. Guards asynchronous scrolling against thread changes.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix

Suggested reviewers: juliusmarminge, yash-singh1

Merge Risk: ⚪ Minimal · up to d9224

Programmatic scrolling now follows the reduced-motion preference on web and mobile, with instant movement when the preference cannot be read. No merge-blocking issue was found. Native mobile behavior was verified only by tests.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 13 files. (1 skipped:…	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the main change: respecting reduced-motion preferences during programmatic scrolling.
Description check	✅ Passed	The description is detailed and directly explains the changes, rationale, scope, validation, and known verification limits. It does not reproduce the template’s explicit Why, UI Changes, or Checklist …

Full details: Docstring Coverage

Explanation

Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 13 files. (1 skipped: 1 unsupported.)

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Dismissing prior approval to re-evaluate d92242b

[juliusmarminge]

Note

This comment is posted by Julius' dot

Closing for missing current motion verification. At d92242b, the change affects web/Electron reveal and scrolling paths plus native mobile scroll-to-end and keyboard timing. I inspected the linked historical desktop recordings and context image. As the description explains, they predate this repair, use a stubbed preference in a proof app, and do not verify the current integrated clients or native behavior.

The focused preference/fallback tests are useful. The verification requirement also calls for before/after UI evidence and a short recording for motion or timing changes. Please provide current web/Electron and native before/after proof covering a live preference change, the affected scroll/reveal actions and mobile keyboard/scroll timing, while showing preserved destinations and focus. Identify the tested commit and results, then request reconsideration.

[saphid]

Following up on the closure for missing current motion verification: the bug is now filed as #15953, with live before/after proof on main a1d9d72aef. The fix is split into two focused replacement PRs:

• fix(web): programmatic scrolls jump instead of glide when Reduce Motion is on #16014 (web/desktop): Scroll to end, PageUp/PageDown, minimap jumps and the theme editor reveal. Measured per frame in Chrome with real prefers-reduced-motion emulation: 72/9/18 intermediate frames on main, 0 on the branch, identical destinations and focus, normal motion unchanged, and a live preference flip applies without a reload.
• fix(mobile): scroll to end jumps instead of glides when Reduce Motion is on #16015 (iOS/Android): Scroll to end and the scroll to a just-sent message. Recorded on an iOS 26.5 simulator with the real Settings switch, including toggling it off and back on while a thread is open.

This branch's fallback-only changes (tabs, settings search, citations) are dropped, because those paths already honor the preference on main. Android and the macOS desktop app with the real system setting are not verified; both PRs say so.