fix(mobile): offer compatible accounts in existing threads

[Brechard]

Native verification on current main

The original restriction is already superseded in orchestration v2. After the request to rebuild on current main, I verified unchanged upstream 1f6df6bf1f50ab5b8e3253716773da2571f8243e on a physical Pixel 8, Android 17 / API 37, on October 11, 2026. No PR code was applied to the tested source.

The Codex adapter supports provider handoffs, mobile reads the thread's switching capability, and the composer offers the catalog when switching is supported. Reintroducing the original continuation-group filter would narrow the choices current upstream supports.

Versions checked on the Pixel

Client	Observed version	Verification
Installed production	1.4.0, native build 74; About also reports 1.4.0	No saved environment connection; inspected version only
Installed Nightly/Preview	2.0.0, native build 1; About reports 2.0.0 Preview	Saved account switch and real follow-up turn against the isolated current-main server
Fresh development client	2.0.0, native fingerprint d19dcee7a4b9037287172c4284a2d5d8620477f7	Built and installed from the tested SHA; switch, save/reopen, follow-up, account removal, and reverse switch

The installed Nightly's existing desktop/server connection reports 0.0.45. The isolated current-main server also reports 0.0.45 but advertises orchestration protocol 2. The version string alone does not identify the server source. Both behavioral passes below used the isolated server at the tested SHA, with two authenticated Codex accounts sharing one Codex home and a disposable Git project. Both accounts used Codex CLI 0.162.1. The installed desktop bundle also reports 0.0.45.

Observed behavior

1. Development client: start a thread with Account A and complete a turn containing a conversation marker.
2. Open the started thread's picker: A and B are both offered. Select B, save, and reopen: B remains selected. Send a follow-up without repeating the marker: B completes it and returns the original marker.
3. Remove B from the isolated configuration and restart the test server. The existing thread still offers A. Save A and send another follow-up: A completes it and retains the marker.
4. Restore B and use the already-installed Nightly app on the same test thread. Select B, save, and reopen: B remains selected. B completes another follow-up and returns the marker.

The persisted server projection confirms four completed runs routed A → B → A → B in the same T3 thread. This demonstrates conversation continuity; it does not claim the provider's native thread ID stays unchanged.

Current-main development client: A selected, B available	B saved and picker reopened

Successful follow-up retaining the earlier marker. Installed Nightly picker after saving and reopening Account B.

Focused verification on the tested SHA:

vp test run apps/mobile/src/state/thread-provider-switching.test.ts apps/mobile/src/lib/modelOptions.test.ts packages/client-runtime/src/state/threadWorkflows.test.ts

45 tests passed across 3 files. No tracked source changes were needed. This PR remains closed, with its original branch preserved.

Limits: the October 9 report using mobile 1.4.1 and server 0.0.45 is not disproved by these 2.0.0/v2 passes. The stable 0.0.45 source retains the old exact-account filter. Mobile 1.4.1, iOS, relay/tunnel behavior, imported legacy threads in a native client, and the separate stale-draft issue were not exercised in this pass. The original PR evidence below is historical.

Original implementation and verification, before orchestration v2

Problem

An existing mobile thread's model picker hides every provider instance except its exact current account. Two compatible Codex accounts sharing one underlying Codex home therefore cannot be selected from the same mobile conversation, even though the web client and Codex account-switching guide support that workflow.

Fixes #14798.

Change

Build existing-thread options from the server's continuation metadata: retain the current instance and include enabled, authenticated instances with the same driver and continuation group. Keep separate session stores, other drivers, and providers requiring a new thread excluded. Without continuation metadata, retain the current exact-instance behavior. The new-thread catalog is unchanged.

Scope and approval

This is a small, focused correction to an obvious mobile restriction on an established, documented capability, under CONTRIBUTING's bug-fix exception. It adds no provider, setting, wire contract, or cross-provider switching feature. The issue records the deterministic reproduction.

Web/desktop already apply continuation compatibility. The mobile composer owns this picker on both iOS and Android; the server remains the authority for validating continuation.

Verification

Base: 54084ae1e6c32809db040e4fa571c80fdf2d8ae4. Current revision: 4e74789e1c408da8813d73035288aaf97fe53446. Visual captures: 76b6d55ad0848e77e870409f2ca1f32e384edb51, before the review follow-up that excludes accounts with unknown authentication. Both recorded accounts were confirmed authenticated; their visible behavior is unchanged by that follow-up.

• vp test run apps/mobile/src/lib/modelOptions.test.ts apps/mobile/src/features/threads/thread-settings-sheet-state.test.ts: 30 tests passed, including compatible accounts, separate homes/drivers, missing metadata, disabled/signed-out accounts, new-thread requirements, and the unchanged new-thread catalog.
• Reinstated the previous exact-instance filtering behavior in the helper: both compatible-account regressions failed. Restored the fix: all tests passed. The additional unknown-authentication regression failed at the original PR head and passed with the review fix, which also preserves the current account when its authentication is unknown.
• vp run --filter @t3tools/mobile typecheck: passed.
• Targeted lint on the three changed files: passed with existing hook warnings in ThreadComposer.tsx.

Native iOS pass: iPhone 17 Pro simulator, iOS 26.5, Expo 58 / React Native 0.88.0-rc.3 development client, local connection to isolated test state. Before and after use the same fixture, viewport, selected Personal account, and thread options. The baseline capture uses the upstream composer; the after capture uses the visual-capture revision stated above.

Before — exact account only	After — compatible accounts

19.1-second guided recording — select Work, save, reopen, switch back to Personal, save, reopen. Both saved choices persisted when reopening the picker. Navigation waits are cut; playback is otherwise real time. The annotations are labeled as a demo guide. This clip verifies saved account selection and submits no agent turn.

Android native development build succeeded against the current upstream Expo 58 / React Native 0.88.0-rc.3 dependencies on S20_API_36 (Android 36, arm64). Opening an existing thread hit an unrelated keyboard-controller scrollViewRef() / Reanimated error with the baseline composer, so the Android interaction pass on this upstream revision remains blocked. No dependency workaround is included in this PR. Remote relay/tunnel modes were not exercised.

Model: GPT-6. Harness: Codex.

Native verification and reassessment: GPT-6.1 Sol (gpt-6.1-sol), Codex harness. Original implementation: GPT-6, Codex harness.

[macroscopeapp]

Approvability

Verdict: Approved at 4e74789

Macroscope's review found this PR approvable — This is a small, self-contained mobile correction that exposes only authenticated accounts sharing the current thread’s existing continuation group, while leaving new-thread behavior and defaults unchanged. Focused tests cover the compatibility and fallback rules, with no schema, infrastructure, or sensitive-area changes.

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Dismissing prior approval to re-evaluate 76b6d55

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📒 Files selected for processing (2)

• apps/mobile/src/lib/modelOptions.test.ts
• apps/mobile/src/lib/modelOptions.ts

🚧 Files skipped from review as they are similar to previous changes (2)

• apps/mobile/src/lib/modelOptions.ts
• apps/mobile/src/lib/modelOptions.test.ts

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📝 Walkthrough

Walkthrough

The mobile thread composer now offers models from compatible provider instances in existing threads. Compatibility depends on matching drivers and continuation groups, authentication status, and whether either provider requires a new thread for model changes. The composer passes all provider groups to the settings route.

Changes

Mobile existing-thread model selection

Layer / File(s)	Summary
Compatible provider choices in thread settings apps/mobile/src/lib/modelOptions.ts, apps/mobile/src/features/threads/ThreadComposer.tsx, apps/mobile/src/lib/modelOptions.test.ts	Adds a helper that filters existing-thread model choices by provider compatibility. The composer uses the helper and passes all provider groups to the settings route. Tests cover compatibility conditions and confirm that new-thread model options remain unrestricted.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 4e747

The existing-thread picker offers compatible accounts while retaining the current account. No actionable merge risk was identified.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 76b6d

Account switching remains constrained by compatibility checks and server validation. No new credential access or authentication bypass was established. Remaining uncertainty concerns interrupted switches and recovery, rather than a demonstrated security defect.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The exposure change is mobile selection of another configured instance for an existing conversation. Candidate instances come from that environment's server configuration and are constrained by driver and continuation group. The changed helper does not accept credentials, arbitrary session-store paths, or a new server target.

Trust Boundaries and Controls

• observed — Server session establishment resolves configured instance identities and rejects unknown instances. For an existing-session instance change, it independently rejects driver differences and incompatible continuation keys. Started-thread model-change restrictions are also checked server-side, so the mobile filter is not the sole continuation control.
• observed — The provider service binds startup to the requested thread and resolved instance, rejects disabled instances and driver mismatches, and checks persisted resume-state compatibility when switching instances. It stamps the resolved instance on the returned session before persisting the binding.

Resilience and Maintainability Implications

• observed — Normal handoff starts the desired session, invokes stale-session cleanup, persists its binding, and updates the thread session. Turn-start failures can publish an error state and failure activity; mobile delivery failures can retain or restore the queued message. These inspected paths do not establish automatic restoration of the previous account after every partial failure or interruption.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Issue #14798 requires compatible Codex instances in the mobile existing-thread picker. The change keeps the selected instance and adds alternatives only when they are enabled, authenticated, use the s…
Out of Scope Changes check	✅ Passed	The changes are limited to mobile existing-thread option filtering, ThreadComposer integration, and focused tests. They do not add a provider or cross-provider switching feature. The new-thread catalo…
Title check	✅ Passed	The title clearly and concisely describes the main change: offering compatible accounts in existing mobile threads.
Description check	✅ Passed	The description includes all required sections. It explains the problem, change, scope and approval basis, focused test results, platform verification, visual evidence, and blocked Android interaction…

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Actionable comments posted: 1

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Inline comments:
Review comments at @apps/mobile/src/lib/modelOptions.ts:
- Around line 164-167: Update the other-instance provider filter in
buildModelOptions to require nextProvider.auth.status to be "authenticated"
before offering its models; preserve the current-instance fallback unchanged.

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Dismissing prior approval to re-evaluate 4e74789

[Brechard]

Verification update for 4e74789e1c408da8813d73035288aaf97fe53446: CI jobs passed; correctness and eligibility reviews approved the latest commit. The authentication finding is fixed with regressions, and its review thread is resolved.

The Effect Service Conventions review was skipped because its prerequisite Check was not discovered within the configured one-minute window. A manual check-run retry returned GitHub HTTP 404. This is an infrastructure skip, not a successful Effect review; this PR changes no Effect service code.

The automatic docstring-coverage warning is non-blocking. The existing model-option helpers use names, types and focused tests to explain their behavior; I kept that local comment style rather than adding coverage-driven docstrings.

[maria-rcks]

Note

Written by claude-opus-5-5 on behalf of Maria

Hi! We are cleaning up open PRs, and this one appears to have been created with an older model (gpt-6). If this change is really important, we recommend rebuilding the PR with a newer model if possible.

[maria-rcks]

Note

Written by claude-opus-5-5 on behalf of Maria

Reopening, this was closed by mistake. Sorry for the noise!

[maria-rcks]

Note

Written by claude-opus-5-5 on behalf of Maria

Closing again after a second look, sorry for the back and forth. This PR has merge conflicts with main. If this change is still important, please rebuild it on current main with a newer model and note the model in the PR description.

[Brechard]

Completed physical-device verification on a Pixel 8 (Android 17 / API 37), using GPT-6.1 Sol in the Codex harness.

Unchanged upstream 1f6df6bf1f50ab5b8e3253716773da2571f8243e already supports the original account-picker workflow. A freshly built mobile 2.0.0 development client offered both authenticated Codex accounts in a started thread, saved Account B, retained it when reopened, and completed a real follow-up that recalled a marker from Account A's earlier turn. After removing B from the isolated server and restarting it, the picker offered A and a follow-up through A also retained the marker. The already-installed Nightly 2.0.0 app then saved/reopened B and completed another follow-up. The server projection confirms four completed runs A → B → A → B in the same T3 thread.

Started-thread picker, saved B after reopening, successful follow-up, installed Nightly picker.

The Pixel's production app reports 1.4.0 (native build 74) and has no saved environment connection. Nightly reports 2.0.0 (native build 1); its existing desktop/server connection reports 0.0.45. Both behavioral passes used an isolated server built from the SHA above. That server also reports 0.0.45 but advertises orchestration protocol 2, so the version string alone does not identify the code. These passes do not disprove the October 9 report on mobile 1.4.1 with the older server release. iOS, relay/tunnel, native legacy-import behavior, and the separate stale-draft issue remain untested in this pass.

All 45 focused tests pass on the tested SHA. The PR description now includes these versions, native evidence, results, and limits. No source changes were needed: the old patch is superseded by v2, so the PR remains closed and the historical branch is preserved.