Naturalize floating bar voice streaming

[kodjima33]

Summary

• switch the default ElevenLabs voice from Rachel to Sloane for a less generic release voice
• make streaming wait for sentence-sized chunks before speaking, with a larger emergency cutoff to avoid stitched robot prosody
• slightly retune ElevenLabs voice settings and align the settings copy with the shipped default voice

Verification

• intended verification target was the Mac mini only
• the Mac mini became unreachable over SSH during this pass, so I could not complete the remote compile/run loop before merging
• root cause for the reported bad voice was verified from source and release tags: v0.11.214 already contains streaming playback, still defaults to generic voices without a custom voice id, and chunks aggressively enough to sound robotic

[greptile-apps]

Greptile Summary

This PR improves voice playback quality in the floating control bar by switching the default ElevenLabs voice from Rachel to Sloane, retuning voice settings for more natural delivery, and significantly reworking the text-chunking heuristic to wait for sentence-level boundaries before handing text off to the TTS API — reducing the "stitched robot prosody" caused by over-eager chunking.

Key changes:

• Default voice ID changed to Sloane (BAMYoBHLZM7lJgJAmFz0) in all three places it appears (service, settings UI, placeholder text).
• Chunk thresholds raised: minimum 48 → 85 chars, preferred 140 → 220 chars, and a new 360-char emergency ceiling added.
• nextChunkBoundary now has three tiers: (1) sentence-ending punctuation within the preferred window, (2) sentence-ending punctuation extended to the emergency window, then (3) clause separators / whitespace / hard cut only when the emergency ceiling is reached.
• ElevenLabs voice settings retuned (stability 0.42 → 0.34, similarity boost 0.82 → 0.88, style 0.22 → 0.12).
• System-voice fallback preference list expanded with "Ava" and "Allison" ahead of "Samantha".
• floatingBarVoiceAnswersEnabled doc-comment de-scoped from "development builds" to all builds.
• Note: Per the PR description, the intended hardware verification target (Mac mini) became unreachable before merging. The logic change was reviewed from source, but a live compile/run cycle was not completed.

Confidence Score: 5/5

• Safe to merge — all findings are minor style suggestions with no functional impact.
• The chunking logic is sound: all index arithmetic is bounded by min(text.count, limit), no infinite-loop risk exists in drainBufferedText, and the ElevenLabs error path already falls back to the system voice. The only finding is a P2 redundant character in the clause-separator set. The unverified hardware run is noted in the PR description as a known gap, not a regression introduced by this change.
• No files require special attention beyond the one P2 style note in FloatingBarVoicePlaybackService.swift.

Important Files Changed

Filename	Overview
desktop/Desktop/Sources/FloatingControlBar/FloatingBarVoicePlaybackService.swift	Default ElevenLabs voice changed from Rachel to Sloane; chunk thresholds raised (min 48→85, preferred 140→220, new emergency 360); voice settings retuned; system voice preference list expanded — one minor redundancy in the clause-separator character set.
desktop/Desktop/Sources/FloatingControlBar/ShortcutSettings.swift	Doc-comment updated to remove "development builds" qualifier, accurately reflecting that voice answers are now a general feature.
desktop/Desktop/Sources/MainWindow/Pages/SettingsPage.swift	UI strings and placeholder voice ID updated from Rachel/21m00Tcm4TlvDq8ikWAM to Sloane/BAMYoBHLZM7lJgJAmFz0 to match the new default.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[New streamed text arrives] --> B{text.count >= minimumChunkLength\n85 chars?}
    B -- No --> WAIT[Return nil — buffer more text]
    B -- Yes --> C[Search preferredSlice\n0..220 chars for '.!?\\n']
    C -- Found --> SPLIT1[Split after last sentence-ending punctuation]
    C -- Not found --> D{text.count >= preferredChunkLength\n220 chars?}
    D -- No --> WAIT
    D -- Yes --> E[Search emergencySlice\n0..360 chars for '.!?\\n']
    E -- Found --> SPLIT2[Split after punctuation in emergency window]
    E -- Not found --> F{text.count >= emergencyChunkLength\n360 chars?}
    F -- No --> WAIT
    F -- Yes --> G[Search emergencySlice for ',;:']
    G -- Found --> SPLIT3[Split after clause separator]
    G -- Not found --> H[Search emergencySlice for whitespace]
    H -- Found --> SPLIT4[Split at last whitespace]
    H -- Not found --> SPLIT5[Hard cut at emergencyLimit]

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_{Reviews (1): Last reviewed commit: "Naturalize floating bar voice streaming" | Re-trigger Greptile}

[greptile-apps]

Redundant \n in clause separator set

At this point in the control flow, the preceding emergencySlice.lastIndex(where: { ".!?\n".contains($0) }) check on the same slice has already returned nil, which guarantees there is no \n character anywhere within emergencySlice. Including \n in ",;:\n" is therefore unreachable dead code on this path.

Suggested change

	if let clauseIndex = emergencySlice.lastIndex(where: { ",;:\n".contains($0) }) {
	if let clauseIndex = emergencySlice.lastIndex(where: { ",;:".contains($0) }) {