fix(delivery): suppress duplicate dictation deliveries [6/6]

[jamditis]

Before submitting

These are required. If you're skipping any, say why in this section.

• I searched existing issues and pull requests (including closed ones) so this isn't a duplicate
• I tested this change locally

Skipping any of the above? Explain why here:

The report arrived while building this stack, but the reporter's OS and paste method are not yet confirmed. This environment also has no Rust toolchain or native input session, so runtime reproduction and the Rust unit tests require CI/a reporter build.

Description

Sixth PR in the v0.6.0 stack; based on codex/v060-lazy-recording-overlay.

Adds an idempotency gate immediately before a delivery can touch clipboard, focus, or keyboard state. A nonzero DictationContext::sequence() can be claimed once; a duplicate job is suppressed and logged before any target-side effect. The recent-sequence set is bounded, poison-recovering, and preserves best-effort behavior for sequence zero.

Static tracing found one enqueue site, one FIFO worker, and one paste chord per normal delivery. This is therefore a defensive containment plus a diagnostic boundary. #310 should remain open until a reporter build confirms whether the duplicate was a second delivery job or one platform chord being interpreted twice.

Related issues

Refs #310

Testing

• Added a one-claim-per-sequence unit test.
• Added a 16-way concurrent duplicate-claim test.
• Added coverage that sequence zero remains best effort.
• git diff --check passes.
• Rust tests and target-app reproduction: CI/native runner required.

Screenshots / videos (optional)

Not applicable; delivery invariant only.

[chatgpt-codex-connector]

Codex Review Summary

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

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-28T22:20:19.648769Z	e3ff28b	PR opened

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[jamditis]

Release coordination: keep this pull request open and do not merge it into main until AudioBud v0.6.0 is public. The signed candidate at e417154 is being replaced because both SBOMs contain placeholder file hashes. Merging now would change the release base and restart validation. Continue review and CI cleanup, then send the final green SHA.

[jamditis]

Release coordination note: protected v0.6.0 candidate run 33230355853 passed at a8f57a3. Keep pull requests 311 through 317 unmerged until v0.6.0 publication is complete. The Office clean Windows lane is requested to test artifact audiobud-windows-x86_64-v0.6.0-1: NSIS, MSI, portable signatures and installs, press-start/press-stop dictation, delivery, target lock, the v0.5.0 updater, and uninstall. Report exact evidence before any merge or publication.

[jamditis]

Release coordination update for August 31: AudioBud v0.6.0 remains frozen before tagging. Clean Windows validation of run 33230355853 is still required: NSIS, MSI, portable, press-start/press-stop dictation, delivery, target lock, startup, tray, quit, uninstall, and the v0.5.0 updater path. Keep PRs 311 through 317 unmerged. Reply only on PR 311 with availability, exact evidence, or a blocker so the test record stays in one thread.