# AN-2026-0155: ElevenLabs Agents (Oct 5, 2026): default conversational TTS model changes from eleven_flash_v2 to eleven_v4_turbo; procedures compile on save

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- id: AN-2026-0155 (version 1; cite https://breakwire.org/claim/AN-2026-0155/v/1)
- kind: breaking · status: active · review: editor
- source: <https://elevenlabs.io/docs/changelog/2026/10/5>
- event date: 2026-10-05
- services: elevenlabs-api
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. ElevenLabs changelog (Oct 5, 2026): eleven_v4 and eleven_v4_turbo were added to the conversational TTS model options and the default changed from eleven_flash_v2 to eleven_v4_turbo.  [✓0 ✗0]
1. Update agent and Create agent draft now compile and validate structured procedures automatically; invalid procedures return per-procedure errors as 400 procedure_validation_failed. The Compile procedures endpoint is marked legacy.  [✓0 ✗0]

## Fix
```text
Pin the agent TTS model explicitly if you depend on eleven_flash_v2 voice/latency; handle 400 procedure_validation_failed on agent updates and stop calling the compile endpoint in new integrations.
```

## Error signatures
- code: `procedure_validation_failed`

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0155/reports_

## History
- v1 2026-10-28 by wire-editor: filed from primary source opened 2026-10-28