fix: detect Tencent SILK (\x02 prefix) in audio magic bytes to avoid ffmpeg failure

[Tom8266]

Root Cause

QQ official bot sends voice messages in Tencent SILK format (leading \x02 byte before #!SILK_V3 magic). _get_audio_magic_type() had two off-by-one slice errors that prevented SILK detection:

1. Standard SILK (line 353): header[:8] == b"#!SILK_V3" — #!SILK_V3 is 9 bytes, so this never matched
2. Tencent SILK: QQ sends \x02#!SILK_V3 — not detected at all

Fix

#	Change	Location
1	Import tencent_silk_to_wav	L18
2	Standard SILK: header[:9] (was [:8])	L353
3	Tencent SILK: header[1:10] (new detection)	L357
4	ensure_wav() routes silk type → tencent_silk_to_wav()	L308

Relationship to #7832

#7832 adds silk/amr routing in ensure_wav(), but does not fix the magic byte detection — _get_audio_magic_type() still never returns "silk". This PR completes the fix by correcting the two off-by-one errors so the detection actually works.

Before / After

Before: QQ voice → magic returns "" → ffmpeg → "Invalid data found" error
After:  QQ voice → magic returns "silk" → tencent_silk_to_wav → WAV OK

Testing

• ✅ Tencent SILK file detected as "silk" (verified with real QQ voice files)
• ✅ Standard SILK file detected as "silk"
• ✅ WAV files still short-circuit correctly
• ✅ All other audio formats (mp3, ogg, flac, amr, opus, mp4) unaffected
• ✅ No circular imports

Fixed by: Tom8266 and deepseek-v4-pro

[sourcery-ai]

Hey - I've left some high level feedback:

• In ensure_wav, the temp output path creation for SILK appears to duplicate logic likely already handled by convert_audio_to_wav for a None output_path; consider centralizing temp path creation to a single place to avoid divergence in behavior.
• In _get_audio_magic_type, the SILK detection logic could be made clearer and less error-prone by using header.startswith(b"#!SILK_V3") and header.startswith(b"\x02#!SILK_V3") instead of explicit slice indices.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- In `ensure_wav`, the temp output path creation for SILK appears to duplicate logic likely already handled by `convert_audio_to_wav` for a `None` `output_path`; consider centralizing temp path creation to a single place to avoid divergence in behavior.
- In `_get_audio_magic_type`, the SILK detection logic could be made clearer and less error-prone by using `header.startswith(b"#!SILK_V3")` and `header.startswith(b"\x02#!SILK_V3")` instead of explicit slice indices.

---

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[gemini-code-assist]

Code Review

This pull request adds support for processing Tencent SILK audio files by updating the magic byte detection logic and integrating a conversion helper. The review suggests refactoring the temporary file path generation to reduce code duplication and improve consistency using pathlib, as well as adopting the more idiomatic startswith method with a tuple for checking file headers.

[gemini-code-assist]

The logic for generating a temporary output path is duplicated here and in convert_audio_format. Using pathlib.Path for consistency and refactoring the path generation to the top of the conversion logic makes the function cleaner and ensures output_path is available for both silk and other formats, adhering to the rule of avoiding code duplication. Furthermore, please ensure this new attachment handling functionality is covered by unit tests.

Suggested change

	if audio_type == "silk":
	if output_path is None:
	temp_dir = get_astrbot_temp_path()
	os.makedirs(temp_dir, exist_ok=True)
	output_path = os.path.join(temp_dir, f"media_audio_{uuid.uuid4().hex}.wav")
	return await tencent_silk_to_wav(audio_path, output_path)
	return await convert_audio_to_wav(audio_path, output_path)
	if output_path is None:
	temp_dir = Path(get_astrbot_temp_path())
	temp_dir.mkdir(parents=True, exist_ok=True)
	output_path = str(temp_dir / f"media_audio_{uuid.uuid4().hex}.wav")
	if audio_type == "silk":
	return await tencent_silk_to_wav(audio_path, output_path)
	return await convert_audio_to_wav(audio_path, output_path)

References

1. When implementing similar functionality for different cases (e.g., direct vs. quoted attachments), refactor the logic into a shared helper function to avoid code duplication.
2. New functionality, such as handling attachments, should be accompanied by corresponding unit tests.

[gemini-code-assist]

Using startswith with a tuple of prefixes is more idiomatic in Python (PEP 8) and less error-prone than manual slicing for magic byte detection, especially when dealing with prefixes of different lengths.

Suggested change

	if header[:9] == b"#!SILK_V3":
	return "silk"
	# Tencent SILK: leading \x02 byte before #!SILK_V3
	if header[:1] == b"\x02" and header[1:10] == b"#!SILK_V3":
	return "silk"
	if header.startswith((b"#!SILK_V3", b"\x02#!SILK_V3")):
	return "silk"

References

1. Using startswith with a tuple of prefixes is more idiomatic in Python (PEP 8) for checking multiple possible prefixes. ^(link)