Second of the two uncovered sweeps I flagged when #3078 merged. Not a
conversion — the conversion is already on main
(`driftedTerminalColumns`, landed by another fleet PR). This is the
coverage it shipped without.
## What was unprotected
Every existing case in this file uses `done` or `archived`, where the
literal is correct. So the terminal check had **no renamed-board case at
all**, and the same measurement that caught #3078 applies: a green file
proves nothing about a conversion whose fixtures can't express the
failure.
What the literal cost on a renamed board: **a durable agent stayed
linked to a finished task forever.** A linked agent is not free to pick
up new work, so the drift this sweep exists to clear is exactly the
drift it stopped clearing.
## Measured, both directions
| case | result |
|---|---|
| agent linked to a task in a RENAMED complete lane is cleared | **fails
on revert** — `taskId` still `"FN-9"`, agent pinned to finished work |
| agent linked to a task still in a RENAMED wip lane keeps its link |
passes either way — the sweep must narrow, not widen |
14 pass on current main; reverting the terminal check to the id pair
fails exactly one.
## Note on the fleet
This sweep was converted by someone else's PR while I was writing the
test for it — I found out because my revert probe hit
`driftedTerminalColumns`, a name I did not write. That is the collision
pattern working in a *useful* direction for once: their conversion, my
coverage, no duplicated code.
It also means the two of us independently chose the same sweep from a
7-PR pileup on this file. Assigning files from the census list would
still be cheaper than discovering the overlap in a test harness.
## Verification
`self-healing-agent-link-drift` **14 passed** · `pnpm test:gate` 13 +
161 + 487 + 71 · lint — green.
f1e96f7a17