Small follow-on to the cross-project cap removal.
`dropPreHeldExecutorSlot(taskId, semaphore?)` released a cross-project
semaphore slot. That semaphore is deleted, and **all 16 production call
sites passed `this.options.semaphore`**, which nothing wires any more —
so the release was a no-op on an always-undefined value: an optional
parameter that reads as if it does something.
## What is *not* deleted
Pre-held slots are **dual-purpose**: a cross-project semaphore slot
**and** the FN-8453 per-project coordinator reservation. Only the first
is gone. The reservation is the half that matters — every rejection path
funnels through this helper so an early scheduler/triage return cannot
permanently consume a project slot — and it stays. That is why this is a
parameter change, not a helper deletion.
Sites that still hold a semaphore reference release it **explicitly**
next to their drop, so behaviour is unchanged for any caller that
supplies one. Nothing wires one in production today, but silently
leaking a slot for a caller that does is not a trade a cleanup is
allowed to make.
## One real leak fixed — found by a failing test, not by reading
`ProjectAdmissionCoordinator.admitOldest`’s release lambda took the
pre-held branch and **returned**, relying on the deleted parameter to
hand the host slot back. With the parameter gone, that branch unwound
the registration and the reservation while **leaking the host slot** the
attempt had acquired. The release is now unconditional across both
branches.
Worth noting how it surfaced: the test that caught it (`drops a declined
candidate’s pre-held executor slot`) asserted `semaphore.activeCount`,
which I had initially assumed was just coupling to the deleted half. It
was not — it was pinning a real invariant.
## Tests
Five cases in `concurrency.test.ts` pinned `sem.activeCount` through a
drop. Each is re-pointed at the surviving contract — registration and
reservation unwound, nothing left for a later pass to “take” — with the
semaphore assertions moved to the sites that now own the release.
## Verification
`pnpm lint` clean · engine `tsc` clean · `pnpm test:gate` green ·
`concurrency.test.ts` **56/56**. The 8 `triage.test.ts` failures are
**pre-existing** — reproduced identically with this branch’s `triage.ts`
replaced by main’s.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
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