Fix Qwen3-ASR hotwords handling

[csukuangfj]

Summary by CodeRabbit

• Bug Fixes
  • Improved hotwords handling in speech recognition to properly use model-level configuration defaults when stream-specific options are not provided.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 0d3067ab-cc53-414a-a4e1-739f42ecb0bd

📥 Commits

Reviewing files that changed from the base of the PR and between 178cee0 and 565d097.

📒 Files selected for processing (2)

• dotnet-examples/non-streaming-qwen3-asr-decode-files/Program.cs
• sherpa-onnx/csrc/offline-recognizer-qwen3-asr-impl.cc

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📝 Walkthrough

Walkthrough

Documentation link update in a .NET example and refinement to hotword prompt generation in Qwen3 ASR implementation. The hotwords feature now defaults to model-level configuration when stream-specific options are absent, with minor code reformatting applied to both files.

Changes

Cohort / File(s)	Summary
Documentation & Formatting dotnet-examples/non-streaming-qwen3-asr-decode-files/Program.cs	Updated reference link from qwen3-asr.html to qwen3-asr, normalized line endings, and adjusted file header formatting. No functional changes.
Qwen3 ASR Configuration sherpa-onnx/csrc/offline-recognizer-qwen3-asr-impl.cc	Modified hotwords prompt generation to use model-level default (qwen3_config.hotwords) when stream lacks explicit hotwords option. Minor code reformatting in token post-processing and condition checking without behavioral changes.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related PRs

• Add hotwords argument to OfflineQwen3ASRModelConfig #3468: Introduces the model-level hotwords field in Qwen3 ASR configuration that is now being utilized as a fallback default in this PR.

Suggested labels

size:XS

Poem

🐰 A link hops to its fresh new home,
Hotwords now find defaults to roam,
Code tidied up with gentle care,
Small tweaks float lightly through the air! ✨

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[gemini-code-assist]

Code Review

This pull request implements a fallback to global hotwords in the Qwen3 ASR decoder and includes minor documentation and formatting improvements. A potential crash was identified in the C++ implementation where a null configuration value could be passed to a string constructor.

[gemini-code-assist]

The logic correctly implements a fallback to the global qwen3_config.hotwords when no per-stream hotwords are provided. However, if qwen3_config.hotwords is a const char * (as defined in the C API struct SherpaOnnxOfflineQwen3ASRModelConfig) and it happens to be nullptr, this ternary expression will cause a crash when constructing the std::string argument for Qwen3FormatHotwordsForPrompt. While the C++ configuration usually initializes this to an empty string, adding a null check or ensuring it defaults to "" is safer.