refactor(stt): drop the unreachable /vad endpoint and stt:vad IPC

[EtienneLescot]

Summary

Removes the speech-detection path added with the Silero VAD pre-pass (#639) that nothing could reach: the preload never exposed stt:vad, so the renderer had no way to call detectSpeech, and the helper's /vad endpoint only served that path.

Removed: POST /vad (helper), detectVadSegments / mergeVadIntervals / MAX_VAD_CHUNK_SAMPLES and the vadAvailable tracking (whisperServer.ts), detectSpeech / isVadAvailable and the stt:vad handler (index.ts), STT_VAD_UNAVAILABLE / SttVadResponse (contract), and their tests.

Kept: the VAD model download, --vad-model, and SttVadSegment. /inference uses the model, and #917 uses the type for its speech intervals.

Related issue

Refs #626

Type of change

• Refactor / maintenance

Release impact

• No release note needed

Desktop impact

• Not platform-specific

Testing

• vitest electron/stt: 87 pass. tsc (app and tests), Biome: clean.
• Helper compiled locally (Windows); build-whisper-stt.yml compiles the other platforms.
• Main only, not for release/v2.0.0. Independent of fix(stt): keep transcript words on the audio's clock when the VAD cuts silence #917 (no overlapping hunks); either can merge first.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Changes
  • Speech-interval detection is no longer available through the app’s speech-to-text service. The related HTTP endpoint and IPC request have been removed.
  • Speech-to-text transcription and cancellation remain available.

[coderabbitai]

Navigate logical layers of code changes, visualize relationships, and explore their blast radius.

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 0a977913-6218-4b33-a9e3-cef705c86dd0

📥 Commits

Reviewing files that changed from the base of the PR and between bc6fa48 and c947095.

📒 Files selected for processing (5)

• electron/native/whisper-stt/src/main.cpp
• electron/stt/index.ts
• electron/stt/transcriptionContract.ts
• electron/stt/whisperServer.test.ts
• electron/stt/whisperServer.ts

💤 Files with no reviewable changes (2)

• electron/native/whisper-stt/src/main.cpp
• electron/stt/transcriptionContract.ts

Included review availability: This review used your included allowance. Your plan provides up to 8 included reviews per hour; 4 remain after this review.

---

📝 Walkthrough

Walkthrough

The change removes VAD detection from the native Whisper HTTP server and Electron STT interfaces. The Whisper server manager no longer tracks VAD availability or provides VAD detection. Transcription and cancellation IPC handling remain.

Changes

VAD support removal

Layer / File(s)	Summary
Remove VAD contracts and IPC electron/stt/transcriptionContract.ts, electron/stt/index.ts	The VAD response contract is removed, and the VAD error marker is replaced with STT_NATIVE_EXTRACTION_UNAVAILABLE. The STT manager and IPC registration no longer expose VAD detection.
Remove native and server VAD handling electron/native/whisper-stt/src/main.cpp, electron/stt/whisperServer.ts, electron/stt/whisperServer.test.ts	The native /vad route and server-side VAD detection are removed. Server readiness and startup results no longer include VAD availability. Tests for VAD behavior are removed.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~12 minutes

Change: Refactor

Suggested reviewers: vitaligusatinsky

Merge Risk: ⚪ Minimal · up to c9470

The change removes an unused speech-detection interface while preserving transcription and inference VAD support. No actionable merge-blocking risk was identified; merge after normal checks pass.

Security Architecture Review

Security architecture risk: ⚪ Minimal · up to c9470

The change removes an unused speech-detection path while preserving transcription, local-only access, and existing startup and cleanup behavior. The reviewed changes do not widen access or weaken an existing security control.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The removed native route had independent loopback HTTP reachability when VAD was available, even though the supported renderer bridge could not invoke it. Its removal narrows the helper's request surface rather than expanding attacker-controlled input or authority.

Trust Boundaries and Controls

• observed — The helper remains unauthenticated and relies on its existing loopback restriction; that condition predates this PR. Retained inference still validates WAV format, removes its temporary upload file, and serializes native inference with a mutex. The exact native diff changes none of these controls.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the removal of the unreachable /vad endpoint and stt:vad IPC path.
Description check	✅ Passed	The description includes the required summary, related issue, change type, release impact, desktop impact, and testing details. The screenshots section is not needed because this is not a UI or visual…
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 3 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Commit to this branch
• Create a new PR

🧪 Generate unit tests (beta)

• Commit to this branch
• Create a new PR

• Autopilot · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

Autopilot is currently an internal CodeRabbit preview.

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}