fix: preserve speaker labels across short ASR gaps

[Optic00]

Description

Speaker labeling previously fell back to an unlabeled transcript whenever an individual diarized turn produced no ASR text. A short silent or unrecognized turn could therefore discard the speaker attribution for the entire recording.

This change tracks those gaps instead of failing immediately. Speaker labels are retained only when every remaining gap is at most 5 seconds and the total omitted audio is at most min(30 seconds, 1% of diarized duration).

When labels are retained despite gaps, FluidVoice stores and displays an explicit limitation notice. The fallback path also logs the actual reason when labels cannot be retained.

Type of Change

• 🐞 Bug fix
• ✨ New feature
• 💥 Breaking change
• 🧹 Chore
• 📝 Documentation update

Related Issue or Discussion

Closes #18

Testing

• Tested on Intel Mac
• Tested on Apple Silicon Mac
• Tested on macOS version: 26.5.2
• Ran linter locally: swiftlint --strict --config .swiftlint.yml Sources
• Ran formatter locally: swiftformat --config .swiftformat Sources
• Ran tests locally: full macOS test suite, 278/278 passing after rebasing onto current origin/main

swiftlint and swiftformat are not installed on the test machine, so these checks are intentionally left unchecked.

Screenshots / Video

Notes

The thresholds are deliberately conservative. Labels are retained only when the omitted material is small enough that the speaker-attributed transcript remains trustworthy.

[greptile-apps]

Greptile Summary

The PR allows speaker labels to survive bounded ASR gaps and records the omitted intervals for persistence, display, and export.

• Adds gap coverage and materiality policy models to the diarized transcription pipeline.
• Persists speaker-labeling notices and gap ranges in current results and file-transcription history.
• Displays limitation notices in current and historical transcription views.
• Adds policy, compatibility, persistence, export, and fallback tests.

Confidence Score: 5/5

The PR appears safe to merge because no blocking failure remains in the eligible follow-up review scope.

No blocking failure remains.

_{Reviews (2): Last reviewed commit: "fix speaker diagnostic lint" | Re-trigger Greptile}