fix(sdk/python): generate_music no longer hardcodes stream=true for non-pcm16 formats

[AbirAbbas]

Summary

OpenRouterProvider.generate_music still hardcoded "stream": True with a default format of wav, so the plain generate_music("...") call reproduced issue #584's 400: 'audio.format' does not support 'wav' when stream=true. Supported values are: 'pcm16'. PR #962 fixed exactly this for generate_audio but did not touch generate_music. This applies the same format-driven transport routing to generate_music, reusing the helpers #962 added (_nonstream_openrouter_audio, _wrap_pcm16_as_wav_b64) rather than duplicating them: wav → wire pcm16 over SSE then re-wrapped client-side as RIFF/WAVE, pcm16 → SSE unchanged, mp3/flac/opus → stream=False via the non-streaming JSON path with label="music".

Everything else about generate_music is unchanged — prompt/duration-hint message shape, model resolution and openrouter/ prefix stripping, duration validation, and the returned MultimodalResponse fields — and there is a test pinning that.

Type of change

• Bug fix
• New feature
• Refactor / cleanup
• Docs only
• Tests only
• CI / tooling
• Breaking change

Test plan

All commands run from sdk/python/.

• uvx ruff@0.15.22 check . → All checks passed!
• uvx ruff@0.15.22 format agentfield/media_providers.py tests/test_openrouter_audio.py tests/test_media_integration.py then uvx ruff@0.15.22 format --check <same files> → 3 files already formatted
• uv run --extra dev ./scripts/run_pytest.sh -p no:cacheprovider → 2009 passed, 4 skipped, 38 deselected in 112.36s, exit 0; coverage TOTAL 2002 stmts / 116 miss / 94%
• uv run --python 3.10 --extra dev ./scripts/run_pytest.sh -p no:cacheprovider --no-cov -q → exit 0 (tests=2013, failures=0, errors=0, skipped=4 from the JUnit summary; this project's -q run does not print the trailing counts line under 3.10)
• Targeted: uv run --extra dev python -m pytest tests/test_openrouter_audio.py tests/test_media_integration.py -p no:cacheprovider --no-cov -q → 68 passed

Red-before-green check: with the media_providers.py change reverted and only the new tests in place, pytest tests/test_openrouter_audio.py::TestOpenRouterMusicFormatRouting fails 4 of 7 — test_default_format_streams_pcm16_and_returns_wav, test_compressed_formats_use_nonstream_json[mp3], test_compressed_formats_use_nonstream_json[flac], test_request_shape_is_identical_across_transports[mp3-False] — i.e. every contract item that describes new behaviour genuinely fails against the old code.

Validation contract

Behaviours this change must exhibit, and the test each maps to (all in sdk/python/tests/test_openrouter_audio.py, class TestOpenRouterMusicFormatRouting, asserting on the payload actually POSTed and on the returned audio via the same aiohttp fake pattern the generate_audio tests use):

#	Behaviour	Test
C1	A default generate_music(prompt=...) call (no format) sends stream: True with audio.format == "pcm16" on the wire, and returns audio whose format is "wav" and whose base64 decodes to a RIFF/WAVE container still containing the streamed pcm bytes.	test_default_format_streams_pcm16_and_returns_wav
C2	format="pcm16" sends stream: True with wire format pcm16 and returns the concatenated base64 verbatim, format "pcm16".	test_pcm16_streams_and_returns_data_untouched
C3	format="mp3" and format="flac" send stream: False to /chat/completions with the requested wire format, and the result is parsed from choices[0].message.audio.{data,transcript}.	test_compressed_formats_use_nonstream_json[mp3], [flac]
C4	A non-200 HTTP response on the non-streaming music path raises RuntimeError whose message contains "music" and the status code.	test_nonstream_http_error_mentions_music_and_status (402 + opus)
C5	The request shape is unchanged versus the current code for the same inputs, and identical across both transports: default model google/lyria-3-pro, openrouter/ prefix stripped, messages == [{"role": "user", "content": "<prompt> (duration: N seconds)"}], modalities == ["text", "audio"]; duration validation still raises ValueError before any HTTP call.	test_request_shape_is_identical_across_transports[wav/pcm16/mp3], test_duration_validation_runs_before_any_request

Two existing tests were re-pinned, not reshaped

test_openrouter_generate_music_streams and test_media_integration.py::test_music_generation_returns_audio requested the default wav format while asserting the raw streamed base64 came back. Only the pcm16 wire path can return that, so both are now pinned to format="pcm16" and additionally assert stream is True — the same treatment #962 gave the two generate_audio SSE tests. Their intent (SSE parsing → AudioOutput) is preserved; the new C1 test covers what the default wav call now does.

Note on the diff

ruff format reflowed two pre-existing f-strings inside _nonstream_openrouter_audio (added by #962, which left them not format-clean). Those two hunks are mechanical and are required for ruff format --check on this file to pass; no other unrelated formatting was touched.

The WAV re-wrap uses sample_rate=24000, matching generate_audio exactly so the two paths stay consistent. The generate_music docstring's "48kHz stereo" line describes the upstream model output, not the client-side mono RIFF header; if OpenRouter's music pcm16 stream turns out to be 48 kHz, that constant should change in both call sites together.

Test coverage

• I ran tests for the surface(s) I changed locally.
• New code paths are covered by tests in this PR (no bare additions). Both new branches in generate_music (non-stream dispatch, wav re-wrap) are exercised by C1/C3/C4.
• If I removed code, I updated coverage-baseline.json in this PR only if the removal caused a legitimate regression and I called it out in the summary above. No code removed; no baseline change.
• The coverage gate check is green in CI before requesting review. Not yet observable — nothing has been pushed.

Checklist

• I have read CONTRIBUTING.md (if present) and docs/DEVELOPMENT.md.
• Commits are signed and follow conventional-commits style.
• I have linked any related issues (Fixes feat(tests): add unit tests for vector memory handler functionality #123 / Closes test: add tests for TypeScript SDK utils (pattern, schema, httpAgents) #456).

Related issues / PRs

Refs #584
Refs #962