The Reliability panel's headline metric is computed from two queries
that name lanes:
```ts
scopedStore.getTaskMovedCountsByDay({ …, toColumn: "in-review" }),
scopedStore.getTaskMovedCountsByDay({ …, fromColumn: "in-review", toColumn: "in-progress" }),
…
const headline = inReviewFailureRate7d(enteredByDay, bouncedByDay, nowMs);
```
On a board that renamed either lane, **both return `{}`**. Every per-day
count is zero, and the headline then divides one zero by another and
reports a healthy rate.
**This is the worst shape a lifecycle defect takes.** It produces a
*number*, not an error, and the number is reassuring. An operator
reading a 0% review-failure rate beside a populated audit event list has
no reason to suspect the metric is blind — the same failure mode as the
analytics `tasksInProgress: 0` sitting next to correct cost totals.
## Why a union is correct here, not a compromise
`getTaskMovedCountsByDay` takes **one** column per side, so the lanes
are resolved to sets and the query is issued per `(from, to)` pair and
summed.
The important part is *why* summing over a union is the right answer
rather than a widening hack. These read **move history**, and a past
move recorded the column name as it was at the time — the same reasoning
that keeps `tasksEnteredInReviewPerDay` in this module matching recorded
values verbatim, marked DELIBERATE-LITERAL. A board renamed last month
therefore has old rows under the old id and new rows under the new one,
so the correct query covers **both**. That is exactly the set
`resolveProjectColumnsForRoles` returns, with the legacy id always
unioned in.
Asking for either name alone is the bug — not a choice between them.
No double-counting: a move event has exactly one `(from, to)` pair, so
the queries partition the events rather than overlapping.
**The common path does not get more expensive.** On the built-in board
this issues the same two queries as before, and there is a test
asserting the call count so a future change cannot quietly turn one
query into N.
## Revert proof (measured)
Collapse the sets back to the single literals:
```
AssertionError: expected { '2026-07-01': 1 } to deeply equal { '2026-07-01': 2, '2026-07-02': 3 }
AssertionError: expected { '2026-07-01': 1 } to deeply equal { '2026-07-01': 2, '2026-07-03': 5 }
```
The helpers live in `reliability-metrics.ts` rather than inline in
`server.ts` specifically so they are testable without booting an express
app.
## Verification
- `pnpm test:gate` — 161 / 487 / 13 / 71 passed
- `pnpm smoke:boot` — PASS (`fn --help`, real `serve` `/api/health` 200,
clean shutdown)
- `pnpm lint` — clean
- `tsc --noEmit` (`@fusion/dashboard`) — clean
- `reliability-metrics.test.ts` — 15 passed
- census `--strict` — exit 0 (unchanged: query filters are not
comparisons)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
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