feat(azure/stt): TrueText post processing option added to STTOptions

[rafallezanko]

https://learn.microsoft.com/en-us/javascript/api/microsoft-cognitiveservices-speech-sdk/propertyid?view=azure-node-latest

SpeechServiceResponse_PostProcessingOption = 39 | A string value specifying which post processing option should be used by service. Allowed values are "TrueText". Added in version 1.7.0

Summary by CodeRabbit

• New Features
  • Added an optional TrueText post‑processing toggle for the Azure speech‑to‑text plugin. When enabled per instance at initialization, transcriptions receive TrueText formatting/cleanup to improve readability and accuracy. Disabled by default and can be turned on for individual speech‑to‑text instances to enhance output quality.

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[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a boolean true_text_post_processing option to the Azure STT plugin: exposed on STT.__init__, stored in STTOptions, and applied in _create_speech_recognizer() by setting the SpeechConfig post-processing option to "TrueText" when enabled.

Changes

Cohort / File(s)	Summary
Azure STT plugin livekit-plugins/livekit-plugins-azure/livekit/plugins/azure/stt.py	Added true_text_post_processing: bool = False to STTOptions; added true_text_post_processing parameter to STT.__init__ and propagated it into STTOptions; updated _create_speech_recognizer() to set SpeechConfig's post-processing option to "TrueText" when the flag is truthy.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐇 I added a switch with a joyful hop,
TrueText whispers and cleans each drop.
A tiny flag to guide the stream,
Words made tidy, neat, and gleam. ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title accurately and specifically describes the main change: adding the TrueText post-processing option to Azure STTOptions, which is the primary focus of the changeset.

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✨ Finishing touches

• 📝 Generate docstrings

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• livekit-plugins/livekit-plugins-azure/livekit/plugins/azure/stt.py

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• livekit-plugins/livekit-plugins-azure/livekit/plugins/azure/stt.py

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[coderabbitai]

Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

livekit-plugins/livekit-plugins-azure/livekit/plugins/azure/stt.py (1)

407-413: Use the correct PropertyId enum: SpeechServiceResponse_PostProcessingOption instead of PostProcessingOption.

The enum speechsdk.enums.PropertyId.PostProcessingOption does not exist in the Azure Speech SDK (1.43.0+). The correct enum name is SpeechServiceResponse_PostProcessingOption (ID: 4003). The current code will raise an AttributeError at runtime.

Fix

-        speech_config.set_property(speechsdk.enums.PropertyId.PostProcessingOption, "TrueText")
+        speech_config.set_property(
+            speechsdk.enums.PropertyId.SpeechServiceResponse_PostProcessingOption,
+            "TrueText",
+        )

🧹 Nitpick comments (1)

livekit-plugins/livekit-plugins-azure/livekit/plugins/azure/stt.py (1)

83-102: Document the new option in the constructor docstring.

The new public parameter isn’t described yet, which makes the API harder to discover.

📌 Suggested docstring update

@@
         Args:
             phrase_list: List of words or phrases to boost recognition accuracy.
                         Azure will give higher priority to these phrases during recognition.
             explicit_punctuation: Controls punctuation behavior. If True, enables explicit punctuation mode
                         where punctuation marks are added explicitly. If False (default), uses Azure's
                         default punctuation behavior.
+            true_text_post_processing: Enables Azure "TrueText" post-processing in the recognition result.

As per coding guidelines, maintain Google-style docstrings for public APIs.

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• livekit-plugins/livekit-plugins-azure/livekit/plugins/azure/stt.py

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**/*.py

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Files:

• livekit-plugins/livekit-plugins-azure/livekit/plugins/azure/stt.py

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (3)

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🔇 Additional comments (2)

livekit-plugins/livekit-plugins-azure/livekit/plugins/azure/stt.py (2)

41-62: LGTM: default-off option is sensible.

The new true_text_post_processing field is a safe, backward-compatible addition.

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141-157: LGTM: option is correctly propagated into STTOptions.

Wiring looks consistent with the other options.

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[rafallezanko]

Hi @chenghao-mou , can you have a look at the MR? Thank you in advance :)