The instructions row of the agent detail panel gets an edit button that
opens the agent's AGENTS.md, as the harness last published it, in a text
box. Save sends a unified diff against the revision that was loaded; when
the agent changed the file meanwhile the editor keeps the operator's text,
shows the agent's version and offers to save over it or take it. An unsaved
edit survives closing the dialog.
The diff is built in the browser (LCS over lines, three lines of context,
git's no-newline marker) and was checked against git apply on 600 random
before/after pairs.
