Terminals froze app-wide several times daily, needing a manual pkill. libuv
unlinks the pathname a server bound to when it closes, with no ownership check,
so a departing daemon deleted whichever socket then sat at the canonical path —
including a live replacement's. The replacement kept hosting PTYs no client
could reach.
#12709 fixed that mechanism; this replaces the shape around it. Two invariants:
only a daemon publishing itself onto the canonical endpoint may mutate that
entry, and only by replacing one it has itself just proven dead; and no actor
removes a name it did not create.
Publish binds a private name, takes the canonical one with an exclusive link,
and on EEXIST proves the incumbent dead by connecting before replacing it in a
single rename. Only 'connected' means occupied and only refused/missing prove
death — a timeout proves nothing and declines. Deletes the claim sweeper, the
reclaim tail of killStaleDaemon, and three unfenced unlinkSync(socketPath)
calls in the launcher.
Measured: rename exposed no gap across 6,525 darwin / 8,004 linux probes of a
live handover, where unlink-then-link gapped on 200 of 200.
Verified on all three platforms: full suite on macOS and Linux, and daemon
restart e2e on a real windows-2022 host. Contract in src/main/daemon/AGENTS.md.
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