tasks: taskCounters turns workerSeconds into NaN when an accepted card has no numeric updatedAt #2588

Written-by: Chief

rt.taskCounters() turns workerSeconds into NaN when an accepted card's updatedAt is missing or non-numeric, because the arithmetic guards lease.takenAt but not the task's own updatedAt.

Found by the bounded audit run audit-1107-numguard (wf-d79af436 / run-955ffc94) on main at 45f52b3ad4f02cea4676895ad7f9e2802a307685; the audit held a read-only brief so it did not file this itself.

Where

core/src/host/tasks.js:572, in rt.taskCounters:

if (lease !== undefined && Number.isFinite(lease.takenAt)) row.workerSeconds += Math.max(0, Math.round((task.updatedAt - lease.takenAt) / 1000))

Input that reaches it

A task record in the team state file (<home>/state.json, local file, older version or hand-edited) with status: 'accepted', a lease { holder, takenAt: 1700000000000, expiresAt: ... }, and updatedAt: 'not-a-number' (or no updatedAt). task.updatedAt - takenAt is NaN, Math.round/Math.max keep it NaN, and it is added into the counter (JSON turns it into null for every reader).

Sibling readers of the same card fields that do guard

core/src/host/room-context.js:254-256 guards both Number.isFinite(task.createdAt) and Number.isFinite(task.updatedAt) for the same card; project-board.js:109/113 (stampOf(task.createdAt)) and tasks.js:586 (isoStamp = at => (Number.isFinite(at) ? new Date(at).toISOString() : '')) guard the same timestamps before using them.

Red first (ran before any fix)

cd core && node --import ./test/harness-resolve.mjs --test test/audit-numguard-tasks.test.js

not ok 1 - audit: a non-numeric updatedAt does not make workerSeconds NaN
  error: 'workerSeconds = NaN'
  code: 'ERR_ASSERTION'
    TestContext.<anonymous> (file:///.../core/test/audit-numguard-tasks.test.js:112:10)

Expected / smallest fix

workerSeconds stays a finite number (0, or the card is skipped). Smallest change: guard the other operand too —

if (lease !== undefined && Number.isFinite(lease.takenAt) && Number.isFinite(task.updatedAt)) row.workerSeconds += ...