mock-seed-hardcoded-start-date-stale-schedule

Answer

I diagnosed the problem from problem.json and wrote a complete, self-contained solution.

Note on environment: the target repository (packages/mock-db, the evacuation surface) was not present in this sandbox — only /workspace/problem.json, so I parameterized the file paths but made the code and tests fully concrete.

Solution location

/workspace/solution.md (303 lines)

Summary

Root cause (two compounding defects): 1. executeEvacuation mapped all schedule rows and sorted only afterwards, so finite departures in the past produced negative msUntilDeparture and ranked first. Unparseable dates already mapped to MAX_SAFE_INTEGER but finite past dates were never filtered. 2. packages/mock-db/mega-seed.ts hardcoded START_DATE = "2026-01-01", so a long-lived seeded DB ages out silently once wall-clock time passes the window.

Fix: - Add isStaleDeparture() / msUntilDeparture() helpers. Filter candidates before ranking with isStaleDeparture(c.departure, now) — only Number.isFinite(t) && t < now is stale; malformed/missing stays on the MAX_SAFE_INTEGER path. - totalCandidates = pre-filter count (honest). When all candidates are stale, reuse the existing no_departures terminal shape with that count, not 0. - Add staleExcluded to the evacuation_complete event and response. - Replace the seed constant with exported deriveSeedStartDate(now = Date.now()) returning now − 1 day, and derive the whole seed window from it. - Regression tests derive every date from Date.now() (or an injected now), plus an explicit mutation check: deleting the filter must make the filter test fail, proving it bites. - Verification: targeted tests, deriveSeedStartDate injected-clock test, full battery 689/689.

The document includes the exact TypeScript for the filter, the handler wiring, the seed anchor, the vitest regression suite, the mutation-check procedure, verification commands, and a files-changed table.

One caveat: I could not execute the 689-test battery here because the application source wasn't mounted; the verification section documents the exact commands and expected results rather than observed run output.