# 463 2026 01 21 Resume Hang Investigation Updated C508743f

> Session Resume Hangs After Tool Calls - UPDATED

- Skill: `tools-only/463-2026-01-21-resume-hang-investigation-updated-c508743f` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add tools-only/463-2026-01-21-resume-hang-investigation-updated-c508743f`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tools-only/463-2026-01-21-resume-hang-investigation-updated-c508743f/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tools-only (https://skillmd.com/u/tools-only)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/tools-only/463-2026-01-21-resume-hang-investigation-updated-c508743f

---


# 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

1. **Tool-call-free sessions resume fine** - You confirmed this
2. **Fresh sessions with tool calls work** - Because they start with empty history
3. **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.