[oddessentials]

What changes

• --headless -- --mcp now starts a windowless relay. It answers list_worlds and list_items itself and opens the Builders window on the first other tool call.
• A new show_window tool opens the window or brings it to the front.
• If the person closes the window, the next tool call opens a new one. A window that fails to start is reported and not relaunched for 10 seconds.
• The relay's list_items reloads custom items another window changed.
• When the agent disconnects, the relay tells the window with a notification instead of closing its pipe. Only a window the relay started acts on it, once.

The disconnect fix (refs #18)

The relay used to close the window's pipe while its reader thread was still reading it. On Windows, if the window wrote anything after that, every later read failed yet returned a byte, so the relay never quit, used a full CPU core and flooded stderr. The window had always saved and exited; the relay was what stayed behind.

Before the fix, on Windows, with a call in flight at disconnect: 6 of 26 runs hung.

Testing

• tests/run.gd -- mcp: 221 passed, 0 failed.
• Packaged Windows build, tests/mcp_smoke.mjs plain and --windowed: 11/11 each. The smoke test now disconnects with a call in flight.
• Packaged Windows build, 50 in-flight disconnects with a headless window: 50 clean.
• Packaged Windows build, 50 in-flight disconnects with a real window: no hangs and no stderr errors. In one run a process was still present about 0.3 seconds after the relay exited (exit 0, item saved); whether it would have exited by itself was not determined.
• macOS: the last commit has not been run on a Mac. The macOS build job's smoke test covers it.

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