Fix playback, deletion, cache reuse, and recording recovery

[r3dbars]

Summary

Six focused repairs to existing behavior, with reproduced regressions and independent review:

• Preserve quiet/overlapping microphone audio in newly generated playback mixes instead of suppressing it based on relative track energy. Original tracks and existing playback files are unchanged.
• Serialize meeting deletion planning and Trash/Undo with transcript writers, reject active retranscription reservations, refresh retained-audio ownership, and reject stale renamed rows using fresh filesystem metadata.
• Show an explicit fallback when support-email handoff fails; retain the feedback draft and change the clipboard only after explicit Copy Address.
• Run the existing conservative legacy-model-cache migration before startup prefetch lookup/download.
• Bind delayed wake recovery to the original recording generation and backend, including after native microphone recovery.
• Classify two actual permission-denial messages correctly without labeling generic unavailable/silent audio as denied.

No language selector, CLI, device picker, playback-regeneration feature, audio-only backend migration, or version/release metadata change is included. The existing audio-only/plus-menu work remains separate.

Verification

• Fresh dependency build and authoritative development app build: passed.
• Full QA bench: PASS, 14 passing steps, zero failures, one non-blocking historical local-log warning.
• Fast runner: 14,090 assertions passed.
• Core package: 1,087 passed, 13 skipped, zero failures. Skips require optional speaker models/corpus or live hardware.
• QA package: 67 tests passed. MCP package: 190 tests passed.
• Model lifecycle production-executor harness: 59 assertions passed with fake model/cache collaborators.
• Real-Core deletion-reservation smoke: 47 assertions passed; temporary synthetic files and redirected Trash only.
• Native navigation smoke: 21 checks passed with isolated test profiles after permission preflight.
• Exact-commit local app: native synthetic meeting rename preserved capture/transcript identity, original date/time and retained audio bytes, with one renamed row visible. All three permission Review buttons opened their expected macOS panes with existing grants unchanged.
• Real file-only Parakeet v3 inference via the existing CLI and explicit cached models, with downloads disabled: all words in a generated 3.89-second sentence matched after case/punctuation normalization. No capture or playback was used; this is not the app import/capture path or a broad accuracy benchmark.
• Existing CLI package with the transcription dependency bundle enabled: 80 tests passed, zero failures; no CLI functionality was added.
• App/Core integration, deterministic artifact E2E, slow pasteback, imported artifacts, round trip, stress, synthetic audio and deterministic release-health fixtures: passed.
• Diff whitespace, source-list and agent preflight checks: passed.

The first full Core run found a test-oracle path alias (/var versus /private/var) in the new repeated-speaker-review test. Both URL sides now resolve symlinks while preserving the exact single-file assertion; the focused regression and full rerun passed. Identity, original date/time and byte-idempotence assertions remain intact.

The local-log warning predates this candidate. It is a warning/error-line frequency, not a recording failure rate; it was investigated rather than cleared or suppressed.

Independent review

An independent agent reviewed the full production diff against main 5785b52b9a72ea8302c3304ea3ddf68c1b6a6482, including the new support dispatcher: no actionable findings remained. A follow-up independent review covered the final test-oracle correction and real-Core deletion harness: no actionable findings. No findings were silently dismissed. Codex coordinated and reviewed; other model lanes were skipped for this bounded Swift repair/test work.

Remaining proof / release boundary

• Real known-speech capture/transcription, remote Zoom/Meet audibility, Bluetooth/USB routes and native interruption/recovery remain unverified on this candidate.
• Native Home deletion removed synthetic captures and offered Undo; native Undo restoration is still unverified because UI automation missed the short window/transient menu state. Detailed speaker/retranscribe flows, restart persistence, native email fallback, real target-app pasteback and installed MCP upgrade need targeted runtime checks.
• Isolated onboarding/navigation is not first-time TCC permission or fresh-install proof; granted/denied/retry checks remain separate.
• The new mix does not regenerate existing playback. Native blocking-microphone interleaving is source-reviewed, not exhaustively runtime-proven.
• Signed/notarized packaging, real Sparkle upgrade, candidate-specific release health and publication parity are not complete. Deterministic health fixtures are not live Sentry health.

This PR is an implemented and locally verified repair batch, not a release approval. No customer communication or distribution surfaces were changed.