improvement(elevenlabs): wire stability and similarity_boost end-to-end

[waleedlatif1]

Summary

• Wired stability and similarityBoost end-to-end (block → tool → contract → proxy route → ElevenLabs voice_settings); previously the tool params were dropped at the contract boundary
• Exposed both knobs in the block under advanced mode
• Renamed tool param similarity → similarityBoost to align with the ElevenLabs API field (similarity_boost) and Sim's unified TTS contract
• Added explicit default to modelId dropdown, cleaned up redundant descriptions, removed duplicate ElevenLabsBlockResponse type, removed unused params arg on headers
• Contract clamps stability / similarityBoost to 0–1

Type of Change

• Improvement

Testing

Tested manually. bun run check:api-validation:strict, biome lint, and tsc --noEmit all clean.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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Project	Deployment	Actions	Updated (UTC)
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[cursor]

PR Summary

Medium Risk
Moderate risk because it changes request/validation and the payload sent to ElevenLabs (new voice_settings and renamed param), which could affect existing integrations if they still send similarity or out-of-range values.

Overview
Adds end-to-end support for ElevenLabs voice tuning by accepting stability and similarityBoost in the TTS API contract, forwarding them through the ElevenLabs tool/block, and sending them to ElevenLabs as voice_settings (with defaults when either knob is provided).

Renames the tool param from similarity to similarityBoost, exposes both fields in the ElevenLabs block as advanced inputs, sets a default modelId dropdown value, and simplifies types by aliasing ElevenLabsBlockResponse to ElevenLabsTtsResponse.

^{Reviewed by Cursor Bugbot for commit abf9443. Configure here.}

[greptile-apps]

Greptile Summary

This PR wires stability and similarityBoost end-to-end for the ElevenLabs TTS block — previously the values were accepted by the tool but silently dropped at the contract boundary before reaching the proxy route. It also renames similarity → similarityBoost to align with the ElevenLabs similarity_boost API field and removes a duplicate type definition.

• Contract fix: ttsToolBodySchema now declares stability and similarityBoost with z.coerce.number().min(0).max(1).optional(), and the route handler builds voice_settings only when at least one knob is set, filling defaults (0.5 / 0.75) for the absent field as required by the ElevenLabs API.
• Block UI: Two short-input fields are exposed under advanced mode with a parseUnitInterval helper that guards against NaN/Infinity before forwarding values to the tool.
• Cleanup: Duplicate ElevenLabsBlockResponse interface collapsed into a type alias of ElevenLabsTtsResponse; unused params arg removed from the headers factory.

Confidence Score: 5/5

Safe to merge — the end-to-end wiring is correct, the type rename is consistent across all five files, and the server-side contract properly validates the new fields.

The contract boundary fix is straightforward and well-scoped. All changed files are internally consistent: the tool, contract, route, block, and types all use the same similarityBoost name. The voice_settings construction correctly handles the partially-set case by filling in ElevenLabs-standard defaults. The only non-blocking finding is that the client-side parseUnitInterval helper accepts out-of-range values that are then rejected server-side, which is a minor UX gap rather than a data correctness issue.

No files require special attention. apps/sim/blocks/blocks/elevenlabs.ts has a minor range-check gap in parseUnitInterval but values outside [0, 1] are correctly rejected by the server contract.

Important Files Changed

Filename	Overview
apps/sim/app/api/tools/tts/route.ts	Correctly destructures stability and similarityBoost from the validated contract body; builds voice_settings only when at least one knob is present, filling in sensible defaults (0.5/0.75) for the absent field.
apps/sim/blocks/blocks/elevenlabs.ts	Adds stability and similarityBoost advanced-mode inputs and a parseUnitInterval guard that filters NaN/Infinity; the guard does not enforce the [0, 1] range client-side.
apps/sim/lib/api/contracts/tools/media/tts.ts	Adds stability and similarityBoost to ttsToolBodySchema with correct z.coerce.number().min(0).max(1).optional() constraints.
apps/sim/tools/elevenlabs/tts.ts	Renames similarity → similarityBoost throughout and removes the unused params argument from the headers factory.
apps/sim/tools/elevenlabs/types.ts	Renames similarity → similarityBoost and collapses the duplicate ElevenLabsBlockResponse interface into a type alias of ElevenLabsTtsResponse.

Sequence Diagram

sequenceDiagram
    participant UI as Block UI (elevenlabs.ts)
    participant Tool as ElevenLabs TTS Tool
    participant Route as /api/tools/tts
    participant EL as ElevenLabs API

    UI->>UI: "parseUnitInterval(stability)<br/>parseUnitInterval(similarityBoost)"
    UI->>Tool: "{ text, voiceId, modelId,<br/>stability, similarityBoost, apiKey }"
    Tool->>Route: "POST /api/tools/tts<br/>body: { ..., stability, similarityBoost }"
    Route->>Route: "ttsToolBodySchema.parse()<br/>z.coerce.number().min(0).max(1)"
    Route->>Route: "hasVoiceSetting?<br/>build voice_settings<br/>with defaults 0.5/0.75"
    Route->>EL: "POST /v1/text-to-speech/{voiceId}<br/>{ text, model_id, voice_settings? }"
    EL-->>Route: audio/mpeg
    Route-->>Tool: "{ audioUrl, audioFile }"
    Tool-->>UI: "{ success, output }"

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[waleedlatif1]

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[waleedlatif1]

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^{Reviewed by Cursor Bugbot for commit abf9443. Configure here.}