fix(ai): openrouter quota publishes a zero-limit window — $0.00 / $0.00 with null percent reads as headroom where there is no limit #1799

Problem

OpenRouter quota publishes a window for a key whose limit is 0: usedPercent: null with the value label $0.00 / $0.00, and the result is ok: true. A zero limit is no quota figure at all — the window reads as a live (empty) quota where the key in fact has no limit/headroom surface. This is exactly the symptom the window contract and a sibling provider already dispositioned:

• Window contract (design(ai): parse the window you were sent, or none — one window contract for the provider quota parsers #1794, packages/ai/src/quota/types.ts rule 4): "No figure, no window — an empty/all-null/zero-limit window-shaped object publishes no window; only quota figures are windows."
• OpenDesign precedent (test(ai): quota suite pins none of claude / meta-billing / opendesign's pure parsers — billing banner rejects numeric strings, claude transform drops legacy windows when limits is non-empty, coding-plan publishes a zero-limit window #1750, comment in packages/ai/src/quota/providers/opendesign.ts parseCodingPlanWindows): a zero limit "used to publish a label-only window (usedPercent null, '0 / 0 credits') that reads as quota headroom where there is no plan" — and now publishes nothing.

OpenRouter was not given the same disposition. The #1795 inventory lists OpenRouter's only known-lossy item as #1725 (unpinned resolveResetAt); the zero-limit case is not covered there.

Evidence (verified this run, main 5fd613e46d)

packages/ai/src/quota/providers/openrouter.ts:

• :105-106 limit / limitRemaining parsed via toNumber.
• :130-133 in the limited branch: used = Math.max(0, limit - limitRemaining), percent = limit > 0 ? (used / limit) * 100 : null — for limit === 0 the percent becomes null but the branch still builds a window.
• :149-152 the window is published unconditionally under the reset-derived key.

Laptop probe (worktree of origin/main 5fd613e46d, driving provider.fetchQuota with a stubbed fetch, probe kept at ~/git/fleet/probe-2026-11-05-creator-2135/probe2.ts on the laptop):

• {limit: 0, limit_remaining: 0, usage_monthly: 0, limit_reset: "monthly"} → ok: true, window monthly: { usedPercent: null, remainingPercent: null, valueLabel: "$0.00 / $0.00", windowSeconds: 2592000, resetAt: <next month> }
• {limit: 0, limit_remaining: -5, usage_monthly: 5, limit_reset: "monthly"} → ok: true, window monthly: { usedPercent: null, valueLabel: "$5.00 / $0.00" } — spent money against a zero limit, still no percent and no error.
• Controls behave: {limit: 100, limit_remaining: -20} → usedPercent: 100, label $120.00 / $100.00; {limit: 100, limit_remaining: 150} → usedPercent: 0, label $0.00 / $100.00.

Why it matters

The opencode quota listing and downstream consumers (aggregator/dashboard) treat an ok: true window as a real quota surface. A zero-limit key (revoked, unpaid, or a free key with no purchased limit) currently shows a plausible monthly window with a reset date instead of the no-data/error row its siblings produce, masking exactly the state a user checks quota to discover.

Acceptance criteria

• A payload with limit: 0 publishes no limit window: if it is the only data, the result follows the sibling no-data contract (ok: false, "No quota data in response"), matching the OpenDesign zero-limit disposition (test(ai): quota suite pins none of claude / meta-billing / opendesign's pure parsers — billing banner rejects numeric strings, claude transform drops legacy windows when limits is non-empty, coding-plan publishes a zero-limit window #1750) and contract rule 4.
• The unlimited path (limit: null with usage_monthly present) still publishes its monthly spent window unchanged.
• Normal and over-limit cases stay as probed above (100 / 150-remaining controls).
• packages/ai/test/quota.test.ts pins the zero-limit case (and the zero-limit-with-spend case) for OpenRouter, in the shared probe-matrix style from test(ai): quota window contract — parser inventory + shared probe matrix for the 13 quota providers (design #1794, phase 1) #1795.
• The test(ai): quota window contract — parser inventory + shared probe matrix for the 13 quota providers (design #1794, phase 1) #1795 parser inventory in types.ts is updated if the fix changes OpenRouter's known-lossy list.

Related: #1794 (window contract), #1725 (OpenRouter resolveResetAt pinning — separate), #1750 (OpenDesign zero-limit precedent).