Keep release artifact writes in the reserved output directory #498

🤖 Generated by the Agentic Engineer

Problem

Replacing the reserved candidate directory before the final copy can redirect preparation into another location while it still reports success. The earlier containment check does not bind the actual write.

Proposed direction

Repair the owning observation or output boundary, with a regression that fails on current main before changing the implementation. Preserve the existing conservative behavior and public interface.

Acceptance criteria

• Bind artifact writes to the exact directory reserved by this invocation and detect output replacement before reporting success.
• Preserve source checkout state and refuse redirected output.
• Test normal output, directory replacement and final artifact/status readback failure through the real preparation command.

Size: S/M. Part of #101.