Catch false-green AI-agent work before you accept it.
Synrail is a local proof gate for coding agents. It does not write code. It asks whether the agent is allowed to claim the task is done.
Agent:
done, tests passed
Synrail: Status: Proof Invalid
Reason: verification command not executed
Next: repair final_result.json
After real verification:
Synrail: Status: Accepted
Only Status: Accepted means the task may be reported as complete.
The skeptical question
Is this just post-review?
Not exactly. A normal post-review asks: is this code good? Synrail asks a narrower question first: is the agent allowed to claim this task is done?
If you personally read every diff, run every check, and track every agent step, Synrail may be unnecessary overhead. In that case, you are already acting as Synrail manually.
Synrail becomes useful when you stop being the runtime supervisor: repeated agent runs, long context, failed repairs, second-operator handoff, or proof-sensitive changes.
Where it fits
Use Synrail when verification debt compounds.
Batch agent work
You ask an agent to update many files or run repeated small tasks, and manual proof tracking starts getting expensive.
Failed repair loops
The agent says it fixed the issue, another agent says it is still broken, and you need a bounded next step instead of chat archaeology.
Handoff-safe proof
A second operator or agent needs to understand what was accepted, what was blocked, why, and what is allowed next.
You may not need Synrail if...
The task is tiny, you inspect every changed line, you run verification yourself, and a false-green costs less than running the gate. Synrail is intentionally not a universal correctness machine.
What Synrail checks
claimed_done != accepted_done
Synrail keeps acceptance separate from execution. The agent can produce code, but the proof gate decides whether the work may be accepted.
Run locally
Try the false-green demo in about two minutes.
The public alpha is a local CLI. It is designed to wrap existing coding-agent workflows, not replace your editor, CI, or code review.
Fallback without make:
python3 -m pip install -e ".[dev]" -c constraints-dev.txt
./examples/false-green-demo/run_demo.sh
Operational transparency
Built in public by NexusShellAI.
Synrail is the current public product of NexusShellAI: a focused developer tool for AI-agent reliability, proof, bounded repair, and handoff.
Alpha feedback
Use Synrail on one real agent task and tell us where it hurts.
The next milestone is not more abstraction. It is 3-5 real external testers using Synrail around Claude Code, Cursor, Codex, Gemini CLI, Aider, or custom agent loops.