[StiensWout]

Valid UTF-8 terminal output can be corrupted when stderr arrives between the bytes of a stdout character. For example, stdout E2, stderr X, stdout 82 AC currently returns �X�� even though both streams contain valid UTF-8.

Decode each pipe independently before appending to the shared byte-budget buffer. This preserves complete characters, literal BOMs, byte-limited truncation, and output snapshots. Resource teardown and EOF ownership are unchanged; #30297 addresses the separate pipe-drain lifecycle issue.

Validation:

• The Deferred-controlled public terminal test fails against main with �X�� and passes with the fix, asserting € and X without requiring their relative order. It also checks readOutputSnapshot.
• All 15 terminal tests pass. The extended multibyte truncation case is additional preservation coverage and already passes on main; it verifies the re-encoded output remains within the byte budget and contains complete characters.
• pnpm exec vp run check:changed passed format, lint, knip, affected-package typechecks and tests (14 affected packages).
• Independent evidence and proof audit passed, including reversed pipe roles, BOM retention, empty output, and partial EOF parity. Hosted CI and reviews are green, as confirmed by the dispatcher.
• Direct service transcript after waitForExit: {"output":"X€","truncated":false,"exitStatus":{"exitCode":0,"signal":null}}.

Standard review depth because the fix adds per-stream decoder state. GPT 6.1 Sol and Claude Opus 5.5 found no required changes. Local cubic reported only the additional truncation-coverage note above. Muse Wonder Full 1.0 review was skipped after API 429 reported its subscription quota exhausted. Optional empty-chunk buffer cleanup was deferred as harmless and outside this fix.

Council review on head 7e6492c4a6dd46e9dd7a6493ebf98ed229181330:

Reviewer	Score	Result
GPT 6.1 Sol	9.5/10	No blocker or should findings
Claude Opus 5.5	9/10	No blocker or should findings

These fresh read-only dispatcher reviews supplement the prior implementation review round above. After Grok 4.7 and backup Muse Wonder Full 1.0 both encountered actual usage-limit failures, Wout explicitly approved: “Use Sol + Opus for this batch.” Neither failed run contributed work or receives model credit.

Implemented, verified, and reviewed by GPT 6.1 Sol through the Codex harness; trimmed and reviewed by Claude Opus 5.5 through the Claude harness, in T3 Code.

[macroscopeapp]

Approvability

Verdict: Approved at 7e6492c

Macroscope's review found this PR approvable — The change preserves UTF-8 characters when terminal stdout and stderr interleave, while retaining literal BOMs. Its scope is limited to buffered output processing, with existing limits, session isolation and process lifecycle unchanged.

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[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

The terminal output pump now decodes stdout and stderr independently as UTF-8 before buffering. Tests cover split UTF-8 characters across interleaved output and truncation limits measured in encoded bytes.

Changes: Terminal UTF-8 output

Layer / File(s)	Summary
Decode terminal output and test byte limits packages/provider-acp/src/server/clientTerminals.ts, packages/provider-acp/src/server/clientTerminals.test.ts	The output pump decodes stdout and stderr independently while preserving literal BOMs. Tests verify split UTF-8 characters remain intact and truncated output respects encoded-byte limits without replacement characters.

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix

Suggested reviewers: juliusmarminge

Merge Risk: Minimal · up to 7e649

No actionable issue is established; the change appears mergeable after normal checks.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly describes the UTF-8 fix for interleaved terminal streams.
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.
Description check		The description clearly explains the problem, change, and verification. It omits the template headings and does not link scope approval or explain why the fix qualifies for an exemption.

Finishing Touches

Generate unit tests (beta)

• Create a new PR

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Recent review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: main
• File: .coderabbit.config.ts
• Commit: 0f4a130
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Advanced
• Run ID: 8c2bd47b-24ce-4693-bd40-55719670b725

Commits

Reviewing files that changed from the base of the PR and between 0f4a130 and 7e6492c.

Files selected for processing: 2

• packages/provider-acp/src/server/clientTerminals.test.ts
• packages/provider-acp/src/server/clientTerminals.ts

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