ROOT CAUSE IDENTIFIED:
The previous "wait for playback duration" workaround was masking the real
issue. Radio Paradise blocks last ~20 minutes (1200s), but the HTTP timeout
was only 180 seconds, causing premature stream termination.
With backpressure from the audio pipeline, HTTP download proceeds at real-time
pace. A 20-minute block takes ~20 minutes to download. The 180s timeout
was killing the connection after 3 minutes, resulting in incomplete blocks.
Changes:
1. **Increase HTTP block_timeout: 180s → 7200s (2 hours)**
- Allows complete download of even the longest blocks
- Comment explains why such a long timeout is needed
2. **Increase MPSC channel sizes: 16 → 60 chunks**
- Matches TimerNode max_lead_time (3.0s / 0.05s = 60 chunks)
- Prevents stop-and-go backpressure pattern
- Allows smooth buffering as intended
3. **Replace workaround with proper channel drainage**
- Use tx.closed().await instead of sleep()
- Guarantees all buffered chunks are processed
- More architecturally sound solution
4. **Add comprehensive diagnostic traces**
- Log expected vs actual block duration
- Detect premature EOF (< 95% of expected duration)
- Track bytes decoded and HTTP Content-Length
- Monitor backpressure blocking with timing
This fixes the streaming completely. The block will now:
- Download for the full ~20 minutes (real-time with backpressure)
- Decode all audio data without truncation
- Process all chunks before pipeline shutdown
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