fix(server): fork Codex threads at native turn boundary by Yusuf007R · Pull Request #9169 · pingdotgg/t3code

Yusuf007R · 2026-09-02T05:07:34Z

Codex 0.151 makes durable threads paginated by default, but T3's retry/edit fork path still truncates a completed native fork with the deprecated thread/rollback endpoint. Codex rejects that endpoint for paginated threads, leaving the provider-turn start failed and the T3 run stuck in its starting state.

What Changed

Resolve the selected durable provider turn to its native Codex turn ID before creating the fork.
Pass that ID as lastTurnId in the original thread/fork request so Codex omits later turns atomically.
Skip the follow-up rollback whenever the native boundary is available.
Preserve the existing rollback-count path only as a compatibility fallback for historical projected turns without a native turn reference.
Cover the native-boundary mapping with a focused adapter test.

Why

The existing flow first creates a complete native fork. If the user selected an earlier turn, T3 counts the terminal turns after that boundary and calls thread/rollback on the newly created thread. Forking at the current head works because the count is zero; retrying or editing an earlier turn reaches the rollback call.

Paginated Codex threads reject that second request with paginated threads do not support thread/rollback. Although Codex has already created the fork, T3 receives an error and fails the durable provider-turn.start effect, so the run appears unresponsive.

Codex already supports the intended operation directly: thread/fork.lastTurnId creates a fork through the specified turn, inclusive. Supplying the known native turn ID removes the incompatible second request without adding recovery, persistence, or provider-version detection machinery.

UI Changes

None. This changes only the Codex provider adapter's native fork request.

Validation

vp test run apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts
vp run --filter t3 typecheck
vp fmt apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts --check

Checklist

This PR is small and focused
I explained what changed and why
Screenshots are not applicable because there are no UI changes
Video is not applicable because there are no animation or interaction changes

Implemented with GPT-5.6 in the Codex desktop harness.

Note

Medium Risk
Changes native fork semantics for retry/edit-at-earlier-turn flows; incorrect boundary mapping could fork with wrong history, though fallback rollback preserves legacy behavior when native ids are missing.

Overview
Codex same-provider forks now cut history at the selected turn in one thread/fork call instead of forking at the head and calling thread/rollback, which paginated Codex threads reject.

The adapter adds resolveCodexForkBoundary, which maps the orchestrator’s source provider turn to its native Codex turn id when nativeTurnRef is present. forkThread includes that id as lastTurnId on thread/fork and sets rollback to zero so the post-fork thread/rollback path is skipped. When there is no native turn reference, behavior stays the same: fork latest state and roll back by the count of later terminal provider turns.

Unit tests cover native-boundary vs identityless fallback. Replay fixtures and orchestration docs were updated to expect lastTurnId and no rollback in the prior-turn fork scenario.

^{Reviewed by Cursor Bugbot for commit 8d034c8. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Fork Codex threads at native turn boundary instead of rollback

Adds resolveCodexForkBoundary to CodexAdapterV2, which returns the source provider turn's native turn id as the fork boundary when available and resets rollback count to zero
Updates the forkThread handler to include the resolved native turn id in the native fork request and skip fork-local rollback in that case; turns without native identity still use the existing latest-state fork plus rollback fallback
Updates replay fixtures in thread_fork_native, thread_fork_native_prior_turn, thread_merge_back_continue, and thread_merge_back_siblings to expect native boundary fork requests and removes explicit rollback exchanges where applicable
Behavioral Change: Codex forks with a native source turn id now fork directly at that turn; forks without native identity are unaffected and retain rollback fallback

^{Macroscope summarized 8d034c8.}

chatgpt-codex-connector · 2026-09-02T05:07:47Z

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-04T15:39:53.412435Z	`2822d10`	Draft marked ready

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: d577d2ca43

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

chatgpt-codex-connector · 2026-09-02T05:11:53Z

+                    ...(forkBoundary.lastTurnId === undefined
+                      ? {}
+                      : { lastTurnId: forkBoundary.lastTurnId }),


Update the fork replay fixture for lastTurnId

When the source turn has a native reference, this now adds lastTurnId to every thread/fork request. The replay harness compares normalized outbound frames exactly and does not remove this field, while testkit/fixtures/thread_fork_native_prior_turn/codex_transcript.ndjson still expects a fork containing only threadId followed by thread/rollback; consequently the focused ThreadFork.integration.test.ts scenario fails before validating the new behavior. Update that transcript to expect the native boundary and remove the obsolete rollback exchange.

AGENTS.md reference: AGENTS.md:L109-L109

Useful? React with 👍 / 👎.

macroscopeapp · 2026-09-02T05:14:43Z

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This is a focused Codex server fix that changes existing fork behavior by using native turn boundaries and retaining a compatibility fallback. Unresolved substantive review comments concern replay validation and null-identity fallback behavior, so the final implementation should receive human review.

^{You can add or adjust custom eligibility rules. Learn more.}

shivamhwp · 2026-09-03T12:12:15Z

Note: GPT-5.6 on behalf of shivam (@shivamhwp).

Please rebase this onto the latest t3code/codex-turn-mapping branch. The base branch was rewritten, so GitHub currently shows 331 unrelated commits, 948 changed files, and merge conflicts instead of the two-file change described here.

After rebasing, please update the Codex replay fixtures for the new thread/fork.lastTurnId request. The fork and merge-back integration tests still expect the old rollback sequence, which is causing the server test failures.

Once the diff is clean and those tests pass, we can review the actual fix.

Dismissing prior approval to re-evaluate 2822d10

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 2822d10f05

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

chatgpt-codex-connector · 2026-09-04T15:39:51Z

+  const nativeTurnRef = boundaryTurn?.nativeTurnRef;
+  if (nativeTurnRef === null || nativeTurnRef === undefined) {
+    return { rollbackTurnCount };
+  }
+
+  return { lastTurnId: nativeTurnRef.nativeId, rollbackTurnCount: 0 };


Treat null native IDs as missing fork boundaries

When a persisted Codex turn has an identity-less provider ref whose nativeId is null (a valid OrchestrationV2ProviderRef), this returns lastTurnId: null and resets rollbackTurnCount to zero. forkThread then sends a null boundary, which is equivalent to omitting the boundary, while also skipping the compatibility rollback; forking from an earlier run therefore retains later turns. Check nativeTurnRef.nativeId for null before disabling rollback.

Useful? React with 👍 / 👎.

Dismissing prior approval to re-evaluate 8d034c8

pingdotgg#4229)

…4457) Update every deterministic Codex turn/start expectation with the explicit user approvals reviewer emitted by the adapter, restoring exact replay coverage and unblocking the merge lane.

…ojects (pingdotgg#3640) Restore versioned shell-cache hydration, reconcile repository enrichment across multiple environments, and decode non-null settled shell timestamps correctly.

) Normalize subagent result disclosure across timeline rendering and collapsed/expanded states. Co-authored-by: codex <codex@users.noreply.github.com>

…dotgg#3754) Expose MCP tools for worktree handoff and status inspection, with focused server and contract coverage. Co-authored-by: codex <codex@users.noreply.github.com>

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: shivam <91240327+shivamhwp@users.noreply.github.com>

…dotgg#9930) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: shivam <91240327+shivamhwp@users.noreply.github.com>

…tgg#9903) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Retry/edit of an earlier turn in a paginated native Codex thread forked at head and then issued thread/rollback, which paginated threads reject. Resolve the selected provider turn nativeTurnRef and pass it as lastTurnId to thread/fork so later turns are excluded atomically and no rollback is needed. Fall back to fork-then-rollback only when no native reference is available, and fail honestly when that fallback hits a paginated fork. rollbackThread now probes historyMode and reports an explicit unsupported error for paginated threads instead of sending a request Codex will reject. Adapts the approach from pingdotgg#9169 by Yusuf007R. Generated with [Devin](https://devin.ai) Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

juliusmarminge · 2026-09-15T07:40:09Z

Stale duplicate of #11490 — same native thread/fork boundary fix, rebased with additional fixtures. Thanks!

github-actions Bot added vouch:unvouched PR author is not yet trusted in the VOUCHED list. size:S 10-29 changed lines (additions + deletions). labels Sep 2, 2026

Yusuf007R marked this pull request as draft September 2, 2026 05:11

chatgpt-codex-connector Bot reviewed Sep 2, 2026

View reviewed changes

juliusmarminge force-pushed the t3code/codex-turn-mapping branch 2 times, most recently from ceea97b to d2f1f51 Compare September 2, 2026 18:07

Yusuf007R force-pushed the codex/fix-codex-paginated-thread-fork branch from d577d2c to fb05690 Compare September 4, 2026 15:14

Yusuf007R marked this pull request as ready for review September 4, 2026 15:29

github-actions Bot added size:M 30-99 changed lines (additions + deletions). and removed size:S 10-29 changed lines (additions + deletions). labels Sep 4, 2026

Yusuf007R marked this pull request as draft September 4, 2026 15:29

macroscopeapp Bot previously approved these changes Sep 4, 2026

View reviewed changes

Yusuf007R marked this pull request as ready for review September 4, 2026 15:35

macroscopeapp Bot previously approved these changes Sep 4, 2026

View reviewed changes

chatgpt-codex-connector Bot reviewed Sep 4, 2026

View reviewed changes

juliusmarminge force-pushed the t3code/codex-turn-mapping branch from 9eeed8c to 8af5734 Compare September 4, 2026 18:23

Yusuf007R force-pushed the codex/fix-codex-paginated-thread-fork branch from 2822d10 to 8d034c8 Compare September 4, 2026 19:31

juliusmarminge force-pushed the t3code/codex-turn-mapping branch 2 times, most recently from 877b9de to b82facd Compare September 5, 2026 04:52

mwolson and others added 6 commits September 4, 2026 21:54

test(orchestrator): Align post-merge CTM fixtures (pingdotgg#4193)

8225fda

fix(orchestrator): Preserve claude/codex post-interrupt recovery state (

f512832

pingdotgg#4229)

test(orchestrator): align Codex approval reviewer replays (pingdotgg#…

480ec84

…4457) Update every deterministic Codex turn/start expectation with the explicit user approvals reviewer emitted by the adapter, restoring exact replay coverage and unblocking the merge lane.

fix(orchestrator): hydrate shell cache and group multi-environment pr…

1bc99ec

…ojects (pingdotgg#3640) Restore versioned shell-cache hydration, reconcile repository enrichment across multiple environments, and decode non-null settled shell timestamps correctly.

feat(subagents): disclose projected results consistently (pingdotgg#3866

d9f84eb

) Normalize subagent result disclosure across timeline rendering and collapsed/expanded states. Co-authored-by: codex <codex@users.noreply.github.com>

Add worktree handoff and status tools to the t3-code MCP server (ping…

87bafc3

…dotgg#3754) Expose MCP tools for worktree handoff and status inspection, with focused server and contract coverage. Co-authored-by: codex <codex@users.noreply.github.com>

Luzivog mentioned this pull request Sep 5, 2026

[Bug]: Codex paginated thread revert fails after restoring workspace files #8958

Closed

2 tasks

saphid and others added 8 commits September 6, 2026 04:24

fix(mobile): render generic message attachments (pingdotgg#9929)

475aa8c

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: shivam <91240327+shivamhwp@users.noreply.github.com>

fix(mobile): use the archive eligibility guard when dispatching (ping…

315f53f

…dotgg#9930) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: shivam <91240327+shivamhwp@users.noreply.github.com>

fix(orchestration): persist linked pull requests (pingdotgg#8689)

792e281

feat(mcp): update thread metadata (pingdotgg#8690)

26a48b0

fix(server): keep old failures from waking snoozed V2 threads (pingdo…

415ed0f

…tgg#9903) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

fix(server): fork Codex threads at native turn boundary

6de4d41

test(server): align Codex fork replay fixtures

87b4b7a

fix(server): preserve Codex fork fallback without native id

e3fc9dd

Yusuf007R force-pushed the codex/fix-codex-paginated-thread-fork branch from 8d034c8 to e3fc9dd Compare September 7, 2026 17:09

juliusmarminge force-pushed the t3code/codex-turn-mapping branch 5 times, most recently from ed5dc41 to 2b1139a Compare September 10, 2026 19:28

cjavad mentioned this pull request Sep 11, 2026

Integrate Codex V2 reliability fixes and native Goals cjavad/t3code#2

Open

juliusmarminge force-pushed the t3code/codex-turn-mapping branch 4 times, most recently from e03e376 to e39429e Compare September 12, 2026 08:17

saphid mentioned this pull request Sep 13, 2026

fix(server): fork Codex threads at the native turn boundary #11490

Merged

juliusmarminge force-pushed the t3code/codex-turn-mapping branch 2 times, most recently from 600a8a5 to d8c75ec Compare September 15, 2026 00:23

juliusmarminge force-pushed the t3code/codex-turn-mapping branch 2 times, most recently from 463d0c6 to e10a1e2 Compare September 15, 2026 06:28

juliusmarminge closed this Sep 15, 2026

Navigation Menu

fix(server): fork Codex threads at native turn boundary - #9169

fix(server): fork Codex threads at native turn boundary#9169
Yusuf007R wants to merge 359 commits into
pingdotgg:t3code/codex-turn-mappingfrom
Yusuf007R:codex/fix-codex-paginated-thread-fork

Yusuf007R commented Sep 2, 2026 •

edited by macroscopeapp Bot

Loading

Uh oh!

chatgpt-codex-connector Bot commented Sep 2, 2026 •

edited

Loading

Uh oh!

chatgpt-codex-connector Bot left a comment

Uh oh!

chatgpt-codex-connector Bot Sep 2, 2026

Uh oh!

macroscopeapp Bot commented Sep 2, 2026 •

edited

Loading

Uh oh!

shivamhwp commented Sep 3, 2026

Uh oh!

chatgpt-codex-connector Bot left a comment

Uh oh!

chatgpt-codex-connector Bot Sep 4, 2026

Uh oh!

juliusmarminge commented Sep 15, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

8 participants

Conversation

Yusuf007R commented Sep 2, 2026 • edited by macroscopeapp Bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

What Changed

Why

UI Changes

Validation

Checklist

Fork Codex threads at native turn boundary instead of rollback

Uh oh!

chatgpt-codex-connector Bot commented Sep 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codex Review Summary

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

chatgpt-codex-connector Bot Sep 2, 2026

Choose a reason for hiding this comment

Uh oh!

macroscopeapp Bot commented Sep 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Approvability

Uh oh!

shivamhwp commented Sep 3, 2026

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

chatgpt-codex-connector Bot Sep 4, 2026

Choose a reason for hiding this comment

Uh oh!

juliusmarminge commented Sep 15, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

8 participants

Yusuf007R commented Sep 2, 2026 •

edited by macroscopeapp Bot

Loading

chatgpt-codex-connector Bot commented Sep 2, 2026 •

edited

Loading

macroscopeapp Bot commented Sep 2, 2026 •

edited

Loading