Mirror of the TTS command-provider registry (PR #17843) for STT. Lets any
shell-driven ASR engine — Doubao ASR, NVIDIA Parakeet, whisper.cpp builds,
SenseVoice, curl pipelines — become an STT backend with zero Python.
Complements the legacy HERMES_LOCAL_STT_COMMAND escape hatch (preserved
untouched via the built-in local_command path) and the
register_transcription_provider() Python plugin hook also shipped in this
PR.
Resolution order (mirrors TTS exactly):
1. Built-in (local, local_command, groq, openai, mistral, xai)
→ native handler. Always wins.
2. stt.providers.<name>: type: command → command-provider runner.
3. Plugin-registered TranscriptionProvider → plugin dispatch.
4. No match → 'No STT provider available'.
Files
-----
- tools/transcription_tools.py: BUILTIN_STT_PROVIDERS frozenset retained;
added _resolve_command_stt_provider_config, _transcribe_command_stt,
and local helpers for template rendering, shell-quote context, and
process-tree termination. Helpers are documented as mirrors of their
tts_tool.py counterparts (kept local to avoid cross-tool private
import). Wire-in is one insertion point in transcribe_audio() after
the xai elif and before the plugin dispatcher. Plugin dispatcher
additionally defensively short-circuits when a same-name command
config exists (command-wins-over-plugin invariant).
- tests/tools/test_transcription_command_providers.py: 50 new tests
covering resolution (builtin precedence, type/command gating,
case-insensitive lookup, legacy stt.<name> back-compat), helpers
(timeout fallback, format validation, iter, has-any), template
rendering (shell-quote contexts, doubled-brace preservation),
end-to-end via _transcribe_command_stt (output_path read, stdout
fallback, timeout, nonzero exit envelope, model override,
language precedence), and dispatcher integration via the real
transcribe_audio() including command-wins-over-plugin and
builtin-shadow-rejection.
- tests/plugins/transcription/check_parity_vs_main.py: extended from
10 to 13 scenarios. New cases: command-provider-installed,
command-vs-plugin-same-name (verifies command wins precedence),
explicit-openai-with-command-shadow (verifies built-in wins).
Adds command_provider dispatch_kind detection via transcript prefix
(CMD: vs PLUGIN:) so command-provider scenarios can be distinguished
from plugin scenarios even when sharing a provider name.
- website/docs/user-guide/features/tts.md: new 'STT custom command
providers' section symmetric to the TTS section — example config,
placeholder grammar table (input_path / output_path / output_dir /
format / language / model), transcript-read-back semantics (file
first, then stdout fallback), optional keys table, behavior notes,
security note. Updated 'Python plugin providers (STT)' to include
the new 'When to pick which (STT)' decision table and updated
resolution-order section (now 4 layers instead of 3).
Verification
------------
189/189 STT targeted tests + 50/50 new command-provider tests pass.
Combined sweep: tests/tools/ 5576/5576, tests/agent/ + tests/hermes_cli/
8623/8623 — zero regressions across 14,199 tests.
Parity harness: 13 scenarios, 9 OK + 4 expected diffs
(no_provider_error → plugin, plugin_unavailable, command_provider × 2).
E2E live-verified in an isolated HERMES_HOME with a real .wav file:
command: → dispatched to stt.providers.my-fake-cli
plugin: → dispatched to registered TranscriptionProvider
command-wins-over-plugin: → command provider beats same-name plugin
builtin-wins-over-command: → built-in OpenAI handler fires;
stt.providers.openai: type: command
does NOT hijack it.
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