Re-land #1464 peek → Amicus tab handoff (reverted in #1503) after root-cause investigation

[CraigBuckmaster]

Tracking issue for re-landing the peek→tab handoff feature that was backed out in #1503 (revert of #1500).

Why it was reverted

TestFlight build 1.0.5 (12) — first build to include #1500 — crashed on first launch immediately after the R2 scripture.db download completed, with:

EXC_CRASH (SIGABRT)
facebook::react::ObjCTurboModule::performVoidMethodInvocation
  (RCTTurboModule.mm:441)
__cxa_rethrow → objc_exception_rethrow → _objc_terminate → abort

Launch-to-crash delta matched the R2 download window. Build (11) (without #1500) was fine. Craig confirmed #1501 was NOT in the crashing bundle, so the only new code between (11) and (12) was #1500 + #1499 (the map probe fix — innocent, only runs when the Map tab mounts).

What was investigated and ruled out

Audit of the 5 files PR #1500 touched (AmicusPeekSheet.tsx, PeekMiniConversation.tsx, promotePeekToThread.ts, and their tests) against the post-download init path:

Suspected cause	Finding
New user.db migration with bad SQL	Not present — #1500 didn't touch userDatabase.ts or add a migration
New @/db/userMutations / TurboModule calls on mount	Not present — promotePeekToThread is only invoked from the "Continue in Amicus tab →" press handler, never at mount
New provider wrapping App.tsx	Not present — no changes to App.tsx, navigation root, or any provider
Eager mount-time effect hitting the DB	Not present — new useState/useCallback/useEffect additions in AmicusPeekSheet are all pure state
useNavigation<NavigationProp<ParamListBase>>() call outside NavigationContainer	The AmicusFab at App.tsx:230 is already a sibling of NavigationContainer and was calling useNavigation + useNavigationState in build (11) without issue, so this isn't a net-new risk
Circular import from promotePeekToThread.ts	None — only type-only import of PeekMessage

Nothing in the audit surfaced an obvious boot-path crash cause. Since the brief prioritizes getting the app launching over a diagnostic fix, we reverted.

Re-land plan

Before re-landing:

1. Reproduce the crash on-device with feat(ai-partner): continue-in-tab handoff from peek (#1464) #1500 applied — get a symbolicated crash log. The Xcode/Sentry stack from build (12) points at RCTTurboModule.mm:441 but doesn't name the module. Capturing the failing selector will pinpoint which TurboModule is being invoked with bad args.
2. Bisect on a physical device — apply feat(ai-partner): continue-in-tab handoff from peek (#1464) #1500 commit-by-commit on top of (11) to confirm which of the 5 file changes triggers the crash, instead of assuming it's feat(ai-partner): continue-in-tab handoff from peek (#1464) #1500 as a whole.
3. Test the hot path in release mode — eas build --profile production → on-device install. Release-mode bundling + Hermes + New Arch often behave differently from Jest, and feat(ai-partner): continue-in-tab handoff from peek (#1464) #1500's tests are all Jest-level.
4. Sanity-check the R2 handoff bridge — since the crash is timing-correlated with the download completing, the suspect may be an interaction between DbDownloadScreen.onComplete (which triggers initDatabase() again + setDbStatus('ready')) and the main tree mounting. Verify nothing feat(ai-partner): continue-in-tab handoff from peek (#1464) #1500 added runs eagerly on first mount of AppShell or AmicusFab.
5. Consider moving the CTA logic out of AmicusPeekSheet — if the re-audit can't isolate the cause, split the service call into a screen-level handler invoked on press only, so module-scope cost is zero.

Branch / commit refs

• Reverted commit: d1ce303 (feature) / 11488ab (merge)
• Revert PR: revert: back out #1500 to unblock TestFlight launch (P0) #1503
• Original feature PR: feat(ai-partner): continue-in-tab handoff from peek (#1464) #1500
• Original issue/epic card: ai-partner: continue-in-tab handoff from peek (re-land with callback pattern) #1464 (parent Epic: Amicus — AI Study Partner (v1) #1446)

/cc @CraigBuckmaster

[CraigBuckmaster]

Full commit refs for re-land

Preservation bookmarks so the reverted code can be found months from now:

Original feature work

• PR: feat(ai-partner): continue-in-tab handoff from peek (#1464) #1500 — feat(ai-partner): continue-in-tab handoff from peek
• Feature commit: d1ce303
• Merge commit: 11488ab
• Original issue: ai-partner: continue-in-tab handoff from peek (re-land with callback pattern) #1464
• Parent epic: Epic: Amicus — AI Study Partner (v1) #1446

Revert

• PR: revert: back out #1500 to unblock TestFlight launch (P0) #1503 — revert: back out #1500 to unblock TestFlight launch (P0)
• Merge commit: 4f5e137

To see the deleted files locally

# See the full feature diff:
git show d1ce303

# Restore a single deleted file temporarily (not committed):
git show d1ce303:app/src/services/amicus/promotePeekToThread.ts > /tmp/promotePeekToThread.ts

# Or check out the feature commit into a local branch for inspection:
git checkout -b inspect-reverted-1500 d1ce303

Files to recover at re-land time

• app/src/components/amicus/AmicusPeekSheet.tsx (modified)
• app/src/components/amicus/PeekMiniConversation.tsx (modified)
• app/src/components/amicus/__tests__/AmicusPeekSheet.test.tsx (new)
• app/src/services/amicus/promotePeekToThread.ts (new)
• app/src/services/amicus/__tests__/promotePeekToThread.test.ts (new)

[CraigBuckmaster]

Closing — subsumed into #1464.

The re-land plan in this tracker has been folded into the revised #1464 card, with two key additions:

1. Architecture change: The re-land uses a callback-based navigation pattern (parent provides navigation, service stays navigation-agnostic) instead of the getParent().navigate() pattern from the original feat(ai-partner): continue-in-tab handoff from peek (#1464) #1500. This fixes up front the anti-pattern that PR Fix iOS map and Amicus crash paths #1562 was trying to address and that Refactor AmicusFab paywall routing to use callback instead of getParent().navigate() #1563 was filed to handle separately — Refactor AmicusFab paywall routing to use callback instead of getParent().navigate() #1563 is also closed as subsumed.

2. Pre-merge validation checkboxes: The three rentamac/release-mode/post-DB-download validation steps from this tracker's re-land plan are now required acceptance criteria on ai-partner: continue-in-tab handoff from peek (re-land with callback pattern) #1464.

The underlying crash from TestFlight build (12) has been fixed at a deeper layer by app/patches/react-native+0.81.5.patch, which patches RCTTurboModule.mm:441 — literally the exact file/line from the crash stack — to re-throw void-method exceptions cleanly. The symptom that forced the revert cannot reoccur with that patch applied. But the validation steps still stand, because we never did the on-device bisect and unit tests didn't catch this class of bug.