feat(quota): add planResolver (DB override > known catalog > empty) (B/F6)

src/lib/quota/planResolver.ts

@@ -0,0 +1,78 @@
+/**
+ * planResolver.ts — Resolve the quota plan for a provider connection.
+ *
+ * Precedence (highest to lowest):
+ *   1. Manual DB override (provider_plans table via getProviderPlan)
+ *   2. Known catalog (planRegistry.ts)
+ *   3. Empty plan (no dimensions — manual configuration required)
+ *
+ * Runtime signals (upstream response headers) are accepted for future
+ * extensibility but ignored in v1.
+ *
+ * Part of: Group B — Quota Sharing Engine (plan 22, frente F6).
+ */
+
+import { getProviderPlan } from "@/lib/localDb";
+import { getKnownPlan } from "./planRegistry";
+import type { ProviderPlan } from "./dimensions";
+
+// ---------------------------------------------------------------------------
+// Types
+// ---------------------------------------------------------------------------
+
+export interface RuntimeSignals {
+  /** Headers from upstream response (e.g. anthropic-ratelimit-unified-5h-utilization). */
+  headers?: Record<string, string>;
+}
+
+// ---------------------------------------------------------------------------
+// Public API
+// ---------------------------------------------------------------------------
+
+/**
+ * Resolve the effective ProviderPlan for a connection.
+ *
+ * @param connectionId   Unique provider connection ID (from DB).
+ * @param provider       Provider name (e.g. "codex", "kimi").
+ * @param runtimeSignals Optional upstream headers / signals (v1: ignored).
+ * @returns              The effective ProviderPlan (never throws).
+ */
+export function resolvePlan(
+  connectionId: string,
+  provider: string,
+  runtimeSignals?: RuntimeSignals // eslint-disable-line @typescript-eslint/no-unused-vars
+): ProviderPlan {
+  // 1. Manual DB override
+  try {
+    const dbPlan = getProviderPlan(connectionId);
+    if (dbPlan && dbPlan.dimensions.length > 0) {
+      return {
+        connectionId: dbPlan.connectionId,
+        provider: dbPlan.provider,
+        dimensions: dbPlan.dimensions as ProviderPlan["dimensions"],
+        source: dbPlan.source,
+      };
+    }
+  } catch {
+    // DB not available (e.g. test env without migration) — fall through
+  }
+
+  // 2. Known catalog
+  const catalogPlan = getKnownPlan(provider);
+  if (catalogPlan) {
+    return {
+      connectionId: null,
+      provider: catalogPlan.provider,
+      dimensions: catalogPlan.dimensions,
+      source: "auto",
+    };
+  }
+
+  // 3. Empty (manual configuration required)
+  return {
+    connectionId: null,
+    provider,
+    dimensions: [],
+    source: "manual",
+  };
+}