meta-exporter: parseSubscriptionQuota's num() reinterprets empty, hex and scientific strings as real measurements — a drifted '' used value exports as a measured 0% window

Evidence (verified this run, main da42bfe7)

pm-stack/meta-exporter/meta-quota-export.mjs, parseSubscriptionQuota (line 69):

const num = (v) => (typeof v === "string" || typeof v === "number" ? Number(v) : NaN);

The console API legitimately sends decimal strings (the captured-payload test at meta-quota-export.test.mjs:19-21 uses "100000000000" / "1023570000"), so accepting strings is intentional. But bare Number() accepts far more than decimal spellings, and the parser's own contract (header, lines 66-68) is "Throws on any shape drift — fail-closed, never partial zeros":

Probe (laptop, importing the real module — file md5 2f76d55332752bd1c43a86505f289007 on both clones; valid control payload, one field mutated per case; probe ~/git/fleet/probe-2026-10-30-laneB-metaempty/):

The existing malformed-reset test (meta-quota-export.test.mjs:157-163) pins "soon", -5, true, {} as fail-closed — "" slips past exactly the guard that test exists to enforce. Only the limit/duration fields are incidentally saved, by their separate zero checks (window_limit = "" → "zero limit"; duration "" → ≤ 0): the used fields have no such backstop, so they are where the fake reading lands.

Why it matters

This exporter's whole design is that "a failed tick can never be mistaken for a reading" (file header). An empty-string used value — the classic shape-drift / missing-value spelling from an upstream API — is currently exported in a status: "ok" document as a measured 0% window, and the quota gatherer ingests it as fact: real usage disappears from the burn/reset display precisely when the console API starts drifting. Hex/scientific spellings are silently reinterpreted into different numbers instead of failing closed.

Acceptance criteria

• parseSubscriptionQuota accepts only plain decimal spellings (the API's actual format, per the captured payload) for its numeric fields: empty, whitespace-only, hex (0x…), scientific (1e…), and otherwise non-decimal strings throw ExportError("unparseable", 6, …), for the used/limit/duration fields and inside resetField / as_of alike.
• window_resets_at = "" on a window with recorded usage fails closed like the absent-reset case; as_of = "" yields consoleAsOf: null or unparseable, never the 1970 epoch.
• New tests in meta-quota-export.test.mjs cover: "" and " " used values rejected; "0x10" / "1e2" used values rejected; "" reset with usage rejected; the captured-payload (decimal-string) test and all existing tests still pass (node --test pm-stack/meta-exporter/).

Dedup

• meta-exporter: subscription-quota timestamps are never range-checked — an ms-scale resets_at exports a year-58790 reset as a successful reading, and an out-of-Date-range value throws a bare RangeError misclassified as fetch-failed #2460 (open) is the timestamp range/plausibility gap (ms-scale and out-of-Date-range values) — a decimal-string or numeric input problem; it does not cover the used fields or the Number("") === 0 coercion, and its fix would not stop a fake 0% window. The "" → 1970 rows above are the same root cause (num()) surfacing in the timestamp fields; fixing num() here also removes those two spellings from meta-exporter: subscription-quota timestamps are never range-checked — an ms-scale resets_at exports a year-58790 reset as a successful reading, and an out-of-Date-range value throws a bare RangeError misclassified as fetch-failed #2460's surface.
• meta-exporter: parseBillingBanner accepts fractional minor units — 1050.5 exports as $10.505 of free credits instead of failing closed on shape drift #2510 (open) is parseBillingBanner accepting fractional numbers — different function, different mechanism (no string coercion).
• supabase-export: parseDbSize/parseRequestCount accept empty, hex, scientific and fractional strings as real measurements — Number("") reads a drifted db-size row as a measured 0-byte database #2743 is the same Number() pattern in supabase-export (different app/file). meta-exporter: window_duration_secs is never validated — a missing/junk duration exports a 'window-NaNs' window as a successful reading #1566 (closed) added the window_duration_secs validation only.