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AlexandGitHub cbbabf6870 chore(asr): remove experimental Parakeet CTC zh-CN Mandarin model (#675)
The experimental Parakeet CTC 0.6B zh-CN model (8.23% mean CER, 14.8x
RTFx on THCHS-30) is dominated by two in-house Mandarin models:
Paraformer-large (2.12% CER, 85x RTFx) and SenseVoice (3.09% CER, 382x
RTFx). There is no remaining use case where the CTC zh-CN model is the
best choice.

Removed:
- CtcZhCnManager / CtcZhCnModels
(Sources/FluidAudio/ASR/Parakeet/SlidingWindow/CTC/)
- ctc-zh-cn-transcribe and ctc-zh-cn-benchmark CLI commands + help text
- .ctcZhCn AsrModelVersion case and the isCtcOnly guard machinery
- Repo.parakeetCtcZhCn / ModelNames.CTCZhCn entries
- THCHS-30 dataset plumbing (ChineseDatasetDownloader, exclusively used
by the zh-CN benchmark)
- CtcZhCnTests and the CTC-only validation tests in AsrModelsTests
- zh-CN benchmark leg in Scripts/parakeet_subset_benchmark.sh
- Documentation: Benchmarks.md zh-CN section, Models.md rows,
DirectoryStructure.md entries, README highlight

Kept (shared with the English CTC 0.6B/110M keyword-spotting path):
CtcDecoder.swift, ARPALanguageModel.swift, and all CTC 110M /
ctc-earnings-benchmark code. The Japanese hybrid TDT model
(parakeet-ctc-0.6b-ja repo naming notwithstanding) is untouched.

Capability gap (follow-up, not blocking): the CTC zh-CN manager had
built-in 15s sliding-window long-form support; the Paraformer and
SenseVoice hosts do not yet chunk long audio. Tracked as a follow-up.

### Why is this change needed?
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2026-06-09 19:40:17 -04:00
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