Completes the family. `check-fnxc-future-dates` was #3287,
`lifecycle-column-census` is #3289, and this is the third and last gate
that rewrote its baseline during a plain check.
## Reproduction
```
inflated one allowance by 6, ran the gate with NO flags
rc=0
entry RESET to 1 ← the check modified the tree it was checking
```
## Why it matters
The tightening is right in substance — an allowance nobody spends is a
hole a literal can be regrown into. Performing it as a **side effect of
checking** handed every worker a byte-identical uncommitted diff they
had not authored, which they then reasonably committed.
Measured across the family: nine PRs chased three defects on
2026-07-31/08-01, two of them (#3283/#3285, five minutes apart, `+0/-1`
each) deleting the **same line neither author wrote**.
#3289 states the class best — *a check that writes turns every reader
into an author*. Two of us separately mis-attributed a gate-written
baseline to our own work while debugging something else.
## Measured, all four directions
| scenario | result |
|---|---|
| plain run, stale baseline | `rc=0`, reports `allowed 7, now 1`;
**inflation survived** — read-only |
| a new SQL literal added | **`rc=1`**, names `__sql_probe.ts` —
regression detection intact |
| `--update-baseline` | `rc=0`, entry written |
| clean tree, plain run | `rc=0`, **zero files dirty** |
Row 2 is the one worth checking: a read-only change to a gate is
worthless if it also stops catching the thing it exists for. The rise
path is untouched.
`census --strict` 0, `check-fnxc-future-dates` 0, eslint clean.
## Correcting my own delay
I measured this defect family on #3267 and then **declined to fix two of
the three**, reasoning that the census *"deliberately fails on a drop"*
so the port might be unsafe. That was wrong: it tightened and exited
`0`, exactly as its own test asserts — *"TIGHTENS on a drop and exits 0,
so somebody else's merge cannot redden the gate."* I had read the
`--exact` contract and attributed it to the default path.
The caution cost hours and prevented nothing. #3289 was written by
someone else in the meantime; this finishes what I should have finished
then.
8d54c5e049