Record close-path checks and state the long-task reason for the floor

[BillyBSig]

Close-path checks and the long-task reason

Summary

• A resume can opt in to carrying kept tool calls and the exact tool text. The default is still one user message with the text prefix. Restart clears that history. The tool-round cap stays 4 unless the caller raises it.
• Protocol tests, with no provider, cover the close file, the one-shot inbox, and the watermark request shape. The public live page records cancel against watermark for three hosted models on that close file.
• The README states why a long task is a reason for the floor, and says this repository does not yet show that contrast.

Out of scope

• A long task where the specialist's own reasoning crowds out an earlier policy
• Publishing to PyPI
• Promoting the eval task hosts into the public import list