Best possible solution:

Land the narrow helper fix after the contributor adds redacted terminal output, logs, a screenshot, or a linked artifact showing a truncated non-ASCII log tail no longer emits a replacement character.

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

Yes from source inspection: current main can retain stdout beginning with a UTF-8 continuation byte and then decode that suffix with Buffer.toString("utf8"). I did not run tests in this read-only review, so this is source-reproducible rather than locally reproduced.

Is this the best way to solve the issue?

Yes, this appears to be the narrowest maintainable fix: normalize only the truncated stdout tail before decoding, leaving stderr and untruncated output behavior alone. The remaining issue is proof, not the code shape.

AGENTS.md: found and applied where relevant.

Codex review notes: model internal, reasoning high; reviewed against bb5979064602.

Label changes:

• add P2: This is a normal-priority CLI diagnostics correctness fix with limited blast radius and no evidence of data loss, security bypass, or runtime availability impact.
• add rating: 🦪 silver shellfish: Overall readiness is 🦪 silver shellfish; proof is 🦪 silver shellfish and patch quality is 🐚 platinum hermit.
• add status: 📣 needs proof: The PR needs real behavior proof before ClawSweeper can clear the contributor ask. Needs real behavior proof before merge: The PR body shows tests/static checks but no after-fix real CLI behavior. Before merge, add a redacted terminal transcript, screenshot, log, or linked artifact from openclaw logs or an equivalent real helper run showing the UTF-8 tail result; updating the PR body should trigger re-review, or a maintainer can comment @clawsweeper re-review. After adding proof, update the PR body; ClawSweeper should re-review automatically. If it does not, the PR author or someone with repository write access can comment @clawsweeper re-review.

Label justifications:

• P2: This is a normal-priority CLI diagnostics correctness fix with limited blast radius and no evidence of data loss, security bypass, or runtime availability impact.
• rating: 🦪 silver shellfish: Overall readiness is 🦪 silver shellfish; proof is 🦪 silver shellfish and patch quality is 🐚 platinum hermit.
• status: 📣 needs proof: The PR needs real behavior proof before ClawSweeper can clear the contributor ask. Needs real behavior proof before merge: The PR body shows tests/static checks but no after-fix real CLI behavior. Before merge, add a redacted terminal transcript, screenshot, log, or linked artifact from openclaw logs or an equivalent real helper run showing the UTF-8 tail result; updating the PR body should trigger re-review, or a maintainer can comment @clawsweeper re-review. After adding proof, update the PR body; ClawSweeper should re-review automatically. If it does not, the PR author or someone with repository write access can comment @clawsweeper re-review.

PR surface:

Source +12, Tests +22. Total +34 across 2 files.

What I checked:

• Current main still decodes a byte-trimmed stdout suffix directly: execFileUtf8Tail on current main trims stdout by bytes and resolves with Buffer.concat(stdoutChunks).toString("utf8"), so a retained suffix beginning with a UTF-8 continuation byte can decode to a replacement character. (src/cli/logs-cli.runtime.ts:31, bb5979064602)
• Runtime entry point is the systemd journal fallback for openclaw logs --follow: readSystemdJournalFallback invokes runtime.execFileUtf8Tail("journalctl", args, { env: process.env, maxBytes }), so the helper owns bounded journal stdout before parsing and redaction. (src/cli/logs-cli.ts:314, bb5979064602)
• PR patch addresses only truncated stdout decoding: The diff adds decodeUtf8Tail, skips leading continuation bytes only when stdout was truncated, and keeps stderr/untruncated decoding behavior unchanged. (src/cli/logs-cli.runtime.ts:10, ce6876e72762)
• Regression coverage targets the claimed byte-boundary failure: The added test emits Buffer.from("é", "utf8") with maxBytes: 1 and expects truncated stdout to be empty rather than a replacement character. (src/cli/logs-cli.runtime.test.ts:58, ce6876e72762)
• Sibling log-tail path was checked: The configured file-log tail already drops a partial first line when byte-bounded reads start mid-file, so the PR's subprocess stdout fix is not obviously missing the same invariant in the file fallback. (src/logging/log-tail.ts:120, bb5979064602)
• Related history for the helper was inspected: The current helper file was introduced on main by de1bac6bc0636199df0d40e2bcc812efd9f01e5b; a prior adjacent PR, fix(cli): handle stdout/stderr stream errors in execFileUtf8Tail #100850, fixed stream-error handling in the same helper but not this UTF-8 boundary issue. (src/cli/logs-cli.runtime.ts:10, de1bac6bc063)

Likely related people:

• sunlit-deng: Git history shows the current logs-cli.runtime.ts and logs-cli.ts files entered main through de1bac6bc0636199df0d40e2bcc812efd9f01e5b, which introduced the helper and journal fallback now being patched. (role: introduced current helper surface; confidence: high; commits: de1bac6bc063; files: src/cli/logs-cli.runtime.ts, src/cli/logs-cli.ts)
• cxbAsDev: Merged fix(cli): handle stdout/stderr stream errors in execFileUtf8Tail #100850 authored adjacent execFileUtf8Tail stream-error handling and tests shortly before this PR. (role: adjacent helper contributor; confidence: medium; commits: d898ff5582b7, 79dcc46a6165, f23ed142e5a2; files: src/cli/logs-cli.runtime.ts, src/cli/logs-cli.runtime.test.ts)
• vincentkoc: GitHub PR metadata for fix(cli): handle stdout/stderr stream errors in execFileUtf8Tail #100850 shows vincentkoc merged the adjacent helper fix and authored the final repair commit on that PR. (role: adjacent merger and repair author; confidence: medium; commits: 6e68bb958cf6, 9606fe43231b; files: src/cli/logs-cli.runtime.ts, src/cli/logs-cli.runtime.test.ts)
• steipete: GitHub metadata for fix(discord): bound gateway websocket payloads #99998 shows steipete merged the PR whose squashed commit introduced the current CLI logs runtime files on main. (role: recent merger and co-author on current CLI log surface; confidence: medium; commits: de1bac6bc063; files: src/cli/logs-cli.runtime.ts, src/cli/logs-cli.ts)

• 🦀 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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