[saphid]

Problem

t3 thread start <project> "<message>" without --title names the thread from the message's first line, cut to 80 characters. The cut counts UTF-16 units, so when an emoji sits right at the cut, the title keeps only the first half of it. The server stores that lone half as U+FFFD, and every client then shows the thread as …aaa�….

To reproduce, start a thread whose first line is 78 characters followed by an emoji and more text.

Change

titleFromMessage now steps the cut back one unit when it would split a surrogate pair. This follows sanitizeThreadTitle from #27483, and #29163 makes the same fix for create_threads titles. The 80-unit limit stays the same. titleFromMessage is exported for the test, the same way waitForRun and readLatestMessages already are.

Scope and approval

This is a very small, focused fix for an obvious bug, so there is no prior issue. A title should never end in a broken character, and the fix reuses the step-back the server already applies to generated titles.

Overlap check: #29163 fixes the same bug in OrchestratorMcpService (create_threads), not the CLI. #24611 changes shared truncate, which this path doesn't call. #28597 (--generate-title) keeps titleFromMessage unchanged as its fallback, so this fix also covers that fallback. A search for titleFromMessage found no other PRs.

Verification

• New case in apps/server/src/cli/thread.test.ts. On main it fails with Received: "aaaa…aaaa�…", Expected: "aaaa…aaaa…" (Tests 1 failed | 6 passed (7)).
• With the fix, vp test run src/cli/thread.test.ts gives 7 passed (7).
• vp run check:changed passed: format, lint, knip, graphql, typecheck (3 packages), test (2 files, 8 passed).
• Not checked: an end-to-end t3 thread start against a running server.

Reviewed with sol-loop: 1 round with GPT-6.1 Sol on high. Sol verdict: approved.

Created with Claude Opus 5.5 in Claude Code (T3 Code).

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Approved at c58d1cc

Macroscope's review found this PR approvable — Generated CLI thread titles now avoid ending with a broken Unicode character when truncated. The existing title limit and explicit-title behavior remain unchanged, keeping the impact limited to title formatting.

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

[coderabbitai]

No actionable comments were generated in the recent review.

Recent review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: main
• File: .coderabbit.config.ts
• Commit: cc59f99
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Advanced
• Run ID: 25dc6899-34a7-44f6-b6f4-8bbce4c7c6c0

Commits

Reviewing files that changed from the base of the PR and between cc59f99 and c58d1cc.

Files selected for processing: 2

• apps/server/src/cli/thread.test.ts
• apps/server/src/cli/thread.ts

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 9 remain after this review.

Walkthrough

The thread title helper is now exported. It truncates first-line titles longer than 80 characters and avoids splitting a UTF-16 surrogate pair. A test checks truncation when an emoji falls at the boundary.

Changes: Thread title truncation

Layer / File(s)	Summary
Title truncation and validation apps/server/src/cli/thread.ts, apps/server/src/cli/thread.test.ts	titleFromMessage truncates titles longer than 80 characters to 79 characters plus an ellipsis. It backs up one code unit if truncation would split a surrogate pair. The test checks a title with an emoji at the boundary.

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

Change: Bug fix

Possibly related issues

• pingdotgg/t3code#26962: The change addresses surrogate-pair handling for message-derived fallback titles, but does not address provider availability.
• pingdotgg/t3code#27702: The change addresses surrogate-pair handling for message-derived titles, but does not change the Cursor retry path.

Suggested reviewers: t3dotgg, only21mil

Merge Risk: Minimal · up to c58d1

No material merge-blocking issue was identified in the title truncation change.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the CLI thread-title bug fix. It identifies the affected behavior and the broken-character outcome.
Description check		The description includes complete Problem, Change, Scope and approval, and Verification sections. It explains reproduction, implementation, approval rationale, test results, and the unverified end-to-…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

The description includes complete Problem, Change, Scope and approval, and Verification sections. It explains reproduction, implementation, approval rationale, test results, and the unverified end-to-end check.

Finishing Touches

Generate unit tests (beta)

• Create a new PR

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

[maria-rcks]

Note

Written by gpt-6.1-sol on behalf of Maria

Verified in a real dev environment

verified as-is at c58d1cc4ce2955468b8479ca1d669665ba2f5d01 on linux, using repo playwright and /usr/bin/google-chrome. created a project pointing at a real git repository through the web app, with fresh isolated state and one dev server at a time. all provider turns used codex gpt-6.1-sol through the local proxy.

• reproduced on github/main (60aec28a9c): t3 thread start with 78 a characters followed by 😀 and more text completed with TITLE_OK, but the saved title ended in \ud83d… and rendered a broken character.
• ran the identical cli command and message on the exact pr head: the turn completed with TITLE_OK; the saved title was exactly 78 a characters plus …, with no split surrogate. opened the actual thread in the web client and inspected it.
• nearby behavior: 77 a characters plus 😀 and more text retained the intact emoji before the ellipsis; explicit --title "Explicit title 😀" was preserved. both real turns completed, their replies rendered, and the explicit title/reply survived browser reload.
• submitted a follow-up through the web composer in the regression thread; the real codex turn replied FOLLOWUP_OK. the recording shows that interaction.
• blacksmith: vp test run apps/server/src/cli/thread.test.ts passed all 7 tests. ci reported 31 successful checks, zero pending/failing. no source changes were needed.

command transcript

Not verified

native desktop and ios/android clients, macos/windows, relay/tunnel connection modes, and other providers were not exercised on this linux vm. this is a cli title-generation change; the real cli/server/codex/web path was exercised.