fix(discord): keep thread title truncation UTF-16 safe by Alix-007 · Pull Request #101307 · openclaw/openclaw

Alix-007 · 2026-07-07T03:10:57Z

What Problem This Solves

Discord thread-title prompt fields were truncated with raw UTF-16 slicing. A limit that landed between an emoji's surrogate pair could send malformed text to the title completion model.

Why This Change Was Made

All three bounded fields now use the existing plugin SDK truncateUtf16Safe helper. Maintainer cleanup keeps the prompt formatter private and tests the real generateThreadTitle completion path instead of exporting production code only for a test.

User Impact

Long Discord message text, channel names, and channel descriptions no longer produce lone UTF-16 surrogates in generated thread-title prompts. Limits and ellipsis behavior are unchanged.

Evidence

Blacksmith Testbox: corepack pnpm test extensions/discord/src/monitor/thread-title.generate.test.ts — 8/8 passed.
Blacksmith Testbox: corepack pnpm check:changed — passed for the final two-file diff.
Canonical oxfmt check and git diff --check — passed.
Fresh Codex autoreview — no findings, correctness 0.99.
Live PR diff verified at 2 files, +19/-2, based directly on current main.

Full Discord/provider delivery was not run: the changed behavior is deterministic prompt construction and is exercised through the production completion entry point with the completion call mocked.

clawsweeper · 2026-07-07T03:49:37Z

Codex review: needs maintainer review before merge. Reviewed July 7, 2026, 3:51 AM ET / 07:51 UTC.

Summary
The PR updates Discord generated thread-title prompt construction to truncate message, channel name, and channel description context with the existing UTF-16-safe helper and adds focused formatter regression coverage.

PR surface: Source +1, Tests +52. Total +53 across 2 files.

Reproducibility: yes. from source inspection: current main uses raw slice at the Discord thread-title prompt truncation limits, so an emoji crossing those limits can leave a lone UTF-16 surrogate. I did not run a local before/after test in this read-only review, but the source path and submitted terminal proof cover the boundary.

Review metrics: none identified.

Merge readiness
Overall: 🐚 platinum hermit
Proof: 🦞 diamond lobster
Patch quality: 🐚 platinum hermit
Result: ready for maintainer review.

Overall follows the weaker of proof and patch quality, so missing proof can cap an otherwise strong patch.

Rank-up moves:

none.

Next step before merge

[P2] No repair-lane work is needed; the contributor PR has sufficient scoped proof, green relevant checks, and no blocking review findings.

Security
Cleared: The diff only changes Discord prompt text truncation and focused tests; it does not alter dependencies, workflows, secrets, auth, network, packaging, or code-execution surfaces.

Review details

Best possible solution:

Land this as a bounded Discord plugin fix after ordinary maintainer review, keeping the existing prompt caps and UTF-16 helper rather than broadening thread-title behavior or adding config.

Do we have a high-confidence way to reproduce the issue?

Yes from source inspection: current main uses raw slice at the Discord thread-title prompt truncation limits, so an emoji crossing those limits can leave a lone UTF-16 surrogate. I did not run a local before/after test in this read-only review, but the source path and submitted terminal proof cover the boundary.

Is this the best way to solve the issue?

Yes; applying the existing truncateUtf16Safe helper at the existing Discord prompt caps is the narrowest maintainable fix. Broader alternatives like changing completion behavior, title sanitization, or unrelated truncation sites are unnecessary for this prompt-context bug.

AGENTS.md: found and applied where relevant.

Codex review notes: model internal, reasoning high; reviewed against 48e77b6abf5e.

Label changes

Label justifications:

P2: The PR fixes malformed Discord thread-title prompt context with a small, channel-scoped change and no config, auth, delivery, storage, or migration impact.
rating: 🐚 platinum hermit: Overall readiness is 🐚 platinum hermit; proof is 🦞 diamond lobster and patch quality is 🐚 platinum hermit.
status: 👀 ready for maintainer look: ClawSweeper has no concrete contributor-facing blocker left for this PR. Sufficient (terminal): The PR body includes current-head terminal proof directly invoking the production formatter with boundary emoji inputs and focused test output for the changed path.
proof: sufficient: Contributor real behavior proof is sufficient. The PR body includes current-head terminal proof directly invoking the production formatter with boundary emoji inputs and focused test output for the changed path.

Evidence reviewed

PR surface:

Source +1, Tests +52. Total +53 across 2 files.

View PR surface stats

Area	Files	Added	Removed	Net
Source	1	8	7	+1
Tests	1	53	1	+52
Docs	0	0	0	0
Config	0	0	0	0
Generated	0	0	0	0
Other	0	0	0	0
Total	2	61	8	+53

What I checked:

Current main behavior: Current main truncates thread-title source text and channel context with raw slice, so a surrogate pair can be split when an emoji crosses the 600/120/320 character limits. (extensions/discord/src/monitor/thread-title.ts:135, 48e77b6abf5e)
PR implementation: The PR imports truncateUtf16Safe, routes prompt construction through buildThreadTitleCompletionUserMessage, and applies safe truncation to both source text and normalized channel context. (extensions/discord/src/monitor/thread-title.ts:136, f062226e814b)
Helper contract: truncateUtf16Safe delegates to sliceUtf16Safe, which adjusts slice boundaries away from dangling high/low surrogate halves. (packages/normalization-core/src/utf16-slice.ts:43, 48e77b6abf5e)
Runtime caller: The Discord auto-thread rename path passes the original message text plus channel name and description into generateThreadTitle, so the changed formatter is on the production prompt path. (extensions/discord/src/monitor/threading.auto-thread.ts:289, 48e77b6abf5e)
Focused regression coverage: The PR adds tests that exercise the generated title prompt and direct formatter path with boundary emoji inputs, asserting no lone surrogate remains for message, channel name, or channel description. (extensions/discord/src/monitor/thread-title.generate.test.ts:224, f062226e814b)
Live PR state: GitHub reports the exact head as mergeable with relevant checks green and proof: sufficient; the submitted proof includes a current-head terminal transcript for the production formatter path. (f062226e814b)

Likely related people:

davidguttman: Authored the merged Discord autoThreadName: generated strategy that introduced the generated thread-title surface and tests. (role: feature origin; confidence: high; commits: aa91000a5d1b; files: extensions/discord/src/monitor/thread-title.ts, extensions/discord/src/monitor/thread-title.generate.test.ts, extensions/discord/src/monitor/threading.auto-thread.ts)
hanamizuki: Authored the merged reasoning-model thread-title budget fix in the same generated thread-title module and tests. (role: recent area contributor; confidence: high; commits: 537479f5b07d, d2b9d918af8a; files: extensions/discord/src/monitor/thread-title.ts, extensions/discord/src/monitor/thread-title.generate.test.ts)
ly-wang19: Authored the merged thread-title wrapper normalization fix in the same module shortly before this PR. (role: recent area contributor; confidence: medium; commits: 2852fa7e3541; files: extensions/discord/src/monitor/thread-title.ts, extensions/discord/src/monitor/thread-title.test.ts)
steipete: Recent history shows multiple simple-completion/plugin-SDK and Discord thread-title refactors by this contributor around the same runtime boundary. (role: adjacent owner; confidence: medium; commits: de20d3a02412, 7785dc21e658, 827b0de0ce74; files: extensions/discord/src/monitor/thread-title.ts, src/plugin-sdk/text-utility-runtime.ts)

What the crustacean ranks mean

🦀 challenger crab: rare, exceptional readiness with strong proof, clean implementation, and convincing validation.
🦞 diamond lobster: very strong readiness with only minor maintainer review expected.
🐚 platinum hermit: good normal PR, likely mergeable with ordinary maintainer review.
🦐 gold shrimp: useful signal, but proof or patch confidence is still limited.
🦪 silver shellfish: thin signal; proof, validation, or implementation needs work.
🧂 unranked krab: not merge-ready because proof is missing/unusable or there are serious correctness or safety concerns.
🌊 off-meta tidepool: rating does not apply to this item.

Shiny media proof means a screenshot, video, or linked artifact directly shows the changed behavior. Runtime, network, CSP, and security claims still need visible diagnostics.

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Review history (5 earlier review cycles)

reviewed 2026-07-07T03:53:42.480Z sha eee9d52 :: needs real behavior proof before merge. :: none
reviewed 2026-07-07T04:54:52.694Z sha 59adc68 :: needs real behavior proof before merge. :: none
reviewed 2026-07-07T05:23:26.672Z sha b5bd0d0 :: needs real behavior proof before merge. :: none
reviewed 2026-07-07T05:33:24.103Z sha f062226 :: needs maintainer review before merge. :: none
reviewed 2026-07-07T05:40:31.750Z sha f062226 :: needs maintainer review before merge. :: none

Alix-007 · 2026-07-07T05:10:02Z

@clawsweeper re-review

I refreshed this against latest main and updated the proof section with current-head focused validation. I avoided broadening production exports only for proof.

clawsweeper · 2026-07-07T05:10:05Z

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Alix-007 · 2026-07-07T05:18:13Z

@clawsweeper re-review

Current head/proof body was refreshed after the last rebase; please re-review the latest head.

clawsweeper · 2026-07-07T05:18:15Z

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Alix-007 · 2026-07-07T05:29:05Z

@clawsweeper re-review

I added a direct prompt formatter path, refreshed the tests, and updated the proof with a standalone Node/tsx transcript from the current head.

clawsweeper · 2026-07-07T05:29:08Z

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Co-authored-by: Alix-007 <[email protected]>

steipete · 2026-07-07T10:17:18Z

Superseded by #101551, landed as 9fb24032215a7f273e8ea3b90286e7d6df6d3f76.

The original fork branch had accumulated unrelated repository ancestry and could not be safely rewritten in place. The replacement preserves @Alix-007's contribution with Co-authored-by, keeps the intended three Discord thread-title truncation points, and upgrades the regression to assert the actual completion payload. Exact-head hosted CI and the native landing workflow passed.

Thank you, @Alix-007. For future PRs, keeping the fork branch narrowly based on current main helps maintainers apply fixups directly; "Allow edits by maintainers" remains useful as well.

Alix-007 · 2026-07-07T10:38:43Z

@steipete is ok ,thx haha

openclaw-barnacle Bot added channel: discord Channel integration: discord size: XS labels Jul 7, 2026

Alix-007 force-pushed the alix/utf16-discord-thread-title branch 3 times, most recently from 73ba19c to 59adc68 Compare July 7, 2026 04:40

Alix-007 force-pushed the alix/utf16-discord-thread-title branch from 59adc68 to b337353 Compare July 7, 2026 05:05

Alix-007 force-pushed the alix/utf16-discord-thread-title branch from b337353 to b5bd0d0 Compare July 7, 2026 05:15

Alix-007 force-pushed the alix/utf16-discord-thread-title branch from b5bd0d0 to f062226 Compare July 7, 2026 05:27

openclaw-barnacle Bot added size: S and removed size: XS labels Jul 7, 2026

steipete self-assigned this Jul 7, 2026

steipete mentioned this pull request Jul 7, 2026

fix(discord): keep thread title prompts UTF-16 safe #101551

Merged

fix(discord): keep thread title truncation UTF-16 safe

035cf30

Co-authored-by: Alix-007 <[email protected]>

steipete mentioned this pull request Jul 7, 2026

docs(changelog): credit Discord thread title fix #101566

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fix(discord): keep thread title truncation UTF-16 safe#101307

fix(discord): keep thread title truncation UTF-16 safe#101307
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