tools-only Session Resume Hangs After Tool Calls - UPDATED
BREAKTHROUGH: History IS Reaching pydantic-ai!
The debug logs now show:
[DEBUG] pydantic-ai ctx.messages count=56
[DEBUG] ctx.messages[0] type=ModelRequest
[DEBUG] Stream init: ... ctx_messages=56 ctx_messages_type=list
This proves the message history is being passed to pydantic-ai correctly!
Current Symptom
- Session has 56 messages with tool calls
- pydantic-ai receives all 56 messages correctly
- Stream receives zero events from provider
- Times out after 30s (stream watchdog) then 120s (global timeout)
What This Changes
OLD theory (DISPROVEN): Message history wasn't reaching pydantic-ai NEW theory: Provider (Chutes/Devstral) is hanging when it receives message history containing tool calls
Evidence
- Tool-call-free sessions resume fine - You confirmed this
- Fresh sessions with tool calls work - Because they start with empty history
- Only resumed sessions with tool call history hang - Provider chokes on the historical tool calls
Root Cause (Revised)
The Chutes provider (mistralai/Devstral-2-123B-Instruct-2512) cannot handle message histories that contain tool calls.
This is likely:
- Provider API limitation/bug
- Model doesn't support tool call history
- Configuration issue with Devstral
Solution
Immediate: Use different provider for sessions with tool call history:
- Claude (Anthropic) - supports tool call history
- GPT-4 (OpenAI) - supports tool call history
- Other models that handle historical tool calls
Long-term: Report to Chutes that Devstral hangs on tool call history.
Key Insight
This is NOT a tunacode bug - it's a provider compatibility issue. Our code works perfectly:
- ✅ Session serialization works
- ✅ pydantic-ai integration works
- ✅ Message history passes correctly
- ❌ Provider rejects tool call history
The fix is to avoid using Chutes/Devstral for complex sessions with tool call history.