Changelog

​

Added

• Server-side request timeout raised from 120 s → 600 s; clients should match. The 25 MB / ~1-hour file-size cap remains.

• New keywords form field on POST /stt. CSV with optional per-term weights, e.g. Acme:5,XYZ Pharma:8.
• The same boost runs on the WebSocket path via the existing context.terms field — no client change required to benefit; existing terms payloads now produce boosted / original markers automatically.
• Words replaced by the boost appear in the response with boosted: true and original: "<pre-boost word>".

• return_timestamps=word adds per-word start / end to the REST response.
• include_confidence=true adds per-word confidence (0-1).

• min_speakers / max_speakers form fields on POST /stt.

• script_correction=true for code-mixed Devanagari / Latin audio.

• snr_db is now a top-level field on every STT response and a per-message field on WS transcription events. Surface as a “good / fair / poor” badge (>= 15 good, 0–15 fair, < 0 poor).

​

Limits

• REST — 429 with error_code: STT_CONCURRENCY_LIMIT / TTS_CONCURRENCY_LIMIT and details.limit.
• WebSocket — error frame followed by close code 1008. The cap releases when an in-flight request completes; no server-side queueing.

​

New error codes

​

New warning codes

​

Billing changes

• WS double-bill fix. Sessions that previously double-billed when the client sent stop are now billed correctly. billing_summary.total_duration_seconds will show as ~50 % of historical values for affected sessions.
• billing_summary.client_estimated_seconds (new, diagnostic) — rough estimate of audio the client sent. Useful only for debugging duration drift; never display as a billed number.
• Low-SNR refunds. REST sessions where upstream dropped audio for low SNR no longer charge the user. WS already handled this.
• Cancellation propagation. Client disconnects mid-request now correctly abort the upstream call. No charge for cancelled requests (499 STT_CLIENT_CANCELLED).
• Diarization surcharge documented. When diarize=true, requests incur a documented +30 % surcharge on top of the base STT rate to cover GPU diarization (pyannote).

​

Plan-tier gate

​

Surface summary

• REST — POST /stt accepts new form fields (keywords, languages, min_speakers, max_speakers, return_timestamps, include_confidence, script_correction, min_split_sec); returns new fields (snr_db, language_source: "long_audio_chunked", per-word boosted/original/confidence, per-segment chunk_idx).
• REST POST /tts, /tts-synthesize, /tts-stream — may now return 429 TTS_CONCURRENCY_LIMIT.
• WebSocket /ws/stt — adds low_snr_dropped to processing_mode; per-word boosted/original; message-level snr_db; concurrency-limit error frame + close 1008; corrected billing_summary with new client_estimated_seconds field.
• WebSocket /ws/tts — concurrency-limit error frame (legacy {error: {message, code, details}} shape) + close 1008.
• Web UI — axios timeout raised to 600 s, error-code-aware toasts, warning_codes surfaced, WS 1008 distinguished from auth/network failures. The 25 MB upload cap is unchanged.

​

Added — Context-gated LLM refinement

​

REST — context: string

curl -X POST https://api.60db.ai/stt \
  -H "Authorization: Bearer $API_KEY" \
  -F "[email protected]" \
  -F "context=Cricket coaching session. Players: Arjun Mehta, Ishaan Verma. Discussing batting technique, stamina, running between wickets."

await client.speechToText(file, {
  language: "auto",
  diarize: true,
  context: "Cricket coaching session. Players: Arjun Mehta, Ishaan Verma.",
});

client.speech_to_text(
    audio_file,
    language='auto',
    diarize=True,
    context='Cricket coaching session. Players: Arjun Mehta, Ishaan Verma.',
)

60db stt:transcribe --file meeting.wav \
  --context "Cricket coaching session. Players: Arjun Mehta, Ishaan Verma."

{
  "audio_url": "https://example.com/meeting.wav",
  "context": "Cricket coaching session. Players: Arjun Mehta, Ishaan Verma."
}

​

WebSocket — structured {general, text, terms}

{
  "type": "start",
  "languages": ["en", "hi"],
  "context": {
    "general": [
      { "key": "domain", "value": "Cricket coaching" },
      {
        "key": "players",
        "value": "Arjun Mehta, Ishaan Verma, Aryan Khan, Rohan"
      }
    ],
    "text": "Coach reviewing a batting practice session.",
    "terms": ["Arjun Mehta", "Ishaan Verma", "off-side", "stamina", "wickets"]
  },
  "config": {
    "encoding": "linear",
    "sample_rate": 48000,
    "continuous_mode": true
  }
}

​

Changed — WebSocket two-phase canonical flow

1. First emit — is_final: true, speech_final: false — fast dict-corrected text. Use for low-latency UI paint and voicebot barge-in / NLU.
2. Canonical — is_final: true, speech_final: true — definitive answer. Either LLM-refined (when llm_applied: true) or the original text re-emitted (when LLM was skipped or failed).

​

Added — Word-preservation guardrails (proxy + UI)

• Refined word-retention guardrail. If the canonical text drops more than ~60% of the first-emit’s token count, the proxy rolls back to the first-emit text and marks llm_applied: false, llm_reason: "dropped_too_many_words". Tuned so legitimate polish (filler removal, 10–40% compression) passes through untouched.
• Hallucination-rejected fallback. When the upstream server’s word-rate guard emits an empty final (processing_mode: "hallucination_rejected", common on fast-paced Indic/English mixed audio), the proxy upgrades it into a tentative canonical using the cached first-emit / last-interim text plus tentative: true and tentative_reason: "hallucination_rejected" so words never silently disappear.

​

Added — Backward-compat refined event handling

​

Surface summary

• REST — POST /stt, POST /v1/transcribe — context: string form field.
• WebSocket — /v1/stream, /ws/stt — context: {general, text, terms} on start; two-phase canonical flow; llm_applied / llm_latency_ms / llm_reason on canonical.
• JavaScript SDK — client.speechToText(audio, { context }).
• Python SDK — client.speech_to_text(audio_file, context=...).
• CLI — 60db stt:transcribe --context "...".
• MCP Server — sixtydb_stt_transcribe accepts context.
• Proxy — word-retention guardrail, hallucination fallback, first-emit caching, legacy refined shim.
• Web UI — context input in Speech-to-Text page and realtime demo; segments rendered with tentative marker when flagged.

​

Environment knobs (server-side)