Closes the last entry I could not pin on the #3115 coverage map — by
establishing **why** it cannot be pinned, rather than leaving it open or
forcing a green test around it.
## `agentParkedColumns` is inert at this call site
It influences exactly one output — `shouldPreserveParkedLink` — and
`recoverAgentsRunningOnInactiveTasks` **never reads it**. The gate is:
```ts
if (proof.hasFreshRun || proof.hasActiveExecution) continue;
```
Neither depends on the lane. So passing a resolved set changes nothing
today, and blinding it back to the legacy ids leaves every test green
**because there is no behaviour to observe**. That is not a coverage gap
— there is nothing there to cover.
## Kept, not deleted
- Removing it makes this call site read as **unwired** to the
lane-wiring ratchet, inviting the next worker to "fix" it by re-adding
exactly this.
- If the gate ever adopts `shouldPreserveParkedLink` — the
parked-specific semantics the sibling sweep uses
(`recoverDriftedAgentTaskLinks`, wired in #3208 an hour ago) — the
resolved set is already correct here.
## The shape worth naming
**Passed-but-unread** is the mirror of the **resolved-gate,
literal-branch** defect #3208 fixed. Both read as converted while
deciding nothing — and only one of them is a bug.
A ratchet that counts call sites cannot tell them apart: #3208's site
looked *unwired* and was a live defect; this one looks *wired* and is
dead code. That is why the distinction belongs in a comment at the site
rather than in a baseline number.
## Map status
**21 of 26 pinned**, 1 established as unpinnable-by-construction, 4
remaining with obstacles recorded:
- `reclaimHoldColumns` / `reclaimReviewColumns` — both audit paths emit
the same `branch:auto-reclaim` type, differing only by a `trigger`
string the branch-level scan also produces.
- `completedHoldColumns`, `wsDoneColumns`, `doneMetaColumns` and others
have since gone green from other workers' PRs.
## Verification
`pnpm test:gate` 13 + 161 + 499 + 71 · lint · census `--strict` ·
fnxc-dates (TZ=UTC) — green. Comment-only change.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Documentation**
* Added an explanatory note clarifying parked-column handling and its
connection to future parked-link preservation behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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