[BUG] Free Code resubmits a tool result after a post-tool provider disconnect

[N0zoM1z0]

Summary

After Free Code submits a completed shell tool result, a transient disconnect in the provider recovery stream causes the same tool result to be submitted again. The standalone reproducer builds public Free Code source at db7d2165a708a9b4904e74bd2e1ab7753bf60901, starts a local mock provider, closes the follow-up stream mid-response, and verifies duplicate tool-result submission without requiring this repository or any private fuzzing harness.

Affected target

• Target: Free Code
• Affected version checked with the public reproducer: db7d2165a708a9b4904e74bd2e1ab7753bf60901
• Current public main checked on 2026-06-19: db7d2165a708a9b4904e74bd2e1ab7753bf60901
• Environment: Linux x86_64 Docker, public source build
• Provider/model: Anthropic-compatible local mock provider, claude-3-5-sonnet-20241022

Steps to reproduce

Prerequisites: Docker, Python 3, and the GitHub CLI (gh) for the clone command below. The linked reproducer is self-contained and uses only Python standard-library modules plus Docker. It builds the affected CLI from public source, starts a local mock provider, and runs the CLI in an isolated workspace. The Docker run is limited to 2 CPUs and 4 GiB RAM by default.

Complete self-contained reproducer: https://gist.github.com/N0zoM1z0/1c2db900f5aef155cc647458cb7ba6d2

The Gist contains free-code-post-tool-transient-disconnect.reproduce.py. Download and run:

gh gist clone 1c2db900f5aef155cc647458cb7ba6d2 free-code-post-tool-transient-disconnect-reproducer
cd free-code-post-tool-transient-disconnect-reproducer
python3 free-code-post-tool-transient-disconnect.reproduce.py

To reuse an already-built local image:

python3 free-code-post-tool-transient-disconnect.reproduce.py --skip-build

Key output from a local run against the affected version:

provider_requests_at_least: observed=3 expected>=2
closed_mid_stream_at_least: observed=2 expected>=1
duplicate_tool_result disconnect_probe: observed=2 expected>=2
REPRODUCED

Actual behavior

Free Code submits the disconnect_probe tool result twice after the provider follow-up stream disconnects mid-response. The reproducer prints REPRODUCED only when it observes provider traffic, a closed mid-stream response, and duplicate tool-result submission for the same call ID.

Expected behavior

Free Code should treat a completed provider-issued tool-call ID as committed, and a retry/recovery path should not resubmit the same tool result.