diff --git a/src/app/api/v1/models/catalog.ts b/src/app/api/v1/models/catalog.ts
index 229a8d7a2c..9ff3385149 100644
--- a/src/app/api/v1/models/catalog.ts
+++ b/src/app/api/v1/models/catalog.ts
@@ -1138,20 +1138,31 @@ export async function getUnifiedModelsResponse(
     const apiKey = extractBearer(request.headers);
     let finalModels = models;
     if (apiKey) {
-      const { isModelAllowedForKey } = await import("@/lib/db/apiKeys");
+      const { isModelAllowedForKey, getApiKeyMetadata } = await import("@/lib/db/apiKeys");
 
-      const filtered = [];
-      for (const m of models) {
-        // m.id is the full identifier (e.g. openai/gpt-4o), m.root is the raw model string
-        // check either one as the config could use either patterns
-        if (
-          (await isModelAllowedForKey(apiKey, m.id)) ||
-          (await isModelAllowedForKey(apiKey, m.root))
-        ) {
-          filtered.push(m);
+      // Quota-exclusive keys (allowedQuotas non-empty): show only the
+      // quotaShared-* virtual models for the key's assigned pools (Phase B3).
+      // This takes precedence over the normal allowedModels filter.
+      const keyMeta = await getApiKeyMetadata(apiKey);
+      if (keyMeta && keyMeta.allowedQuotas && keyMeta.allowedQuotas.length > 0) {
+        const { resolveQuotaKeyScope } = await import("@/lib/quota/quotaKey");
+        const { filterModelsToQuotaPools } = await import("@/lib/quota/quotaCombos");
+        const scope = await resolveQuotaKeyScope(keyMeta.allowedQuotas);
+        finalModels = filterModelsToQuotaPools(models, scope.poolSlugs);
+      } else {
+        const filtered = [];
+        for (const m of models) {
+          // m.id is the full identifier (e.g. openai/gpt-4o), m.root is the raw model string
+          // check either one as the config could use either patterns
+          if (
+            (await isModelAllowedForKey(apiKey, m.id)) ||
+            (await isModelAllowedForKey(apiKey, m.root))
+          ) {
+            filtered.push(m);
+          }
         }
+        finalModels = filtered;
       }
-      finalModels = filtered;
     }
 
     const getDefaultContextFallback = (model: any): number | undefined => {
diff --git a/src/lib/quota/quotaCombos.ts b/src/lib/quota/quotaCombos.ts
index 3bd4004a2d..0e76dcd96a 100644
--- a/src/lib/quota/quotaCombos.ts
+++ b/src/lib/quota/quotaCombos.ts
@@ -171,6 +171,33 @@ export async function syncQuotaCombos(poolId: string): Promise<void> {
   }
 }
 
+// ---------------------------------------------------------------------------
+// Catalog filter helper (Phase B3)
+// ---------------------------------------------------------------------------
+
+/**
+ * Given a flat model list and a set of pool slugs, return only the entries
+ * whose `id` is a `quotaShared-*` virtual model name AND whose parsed
+ * `poolSlug` is in `poolSlugs`.
+ *
+ * Fail-closed: an empty `poolSlugs` array returns an empty list — a
+ * quota-exclusive API key with no resolvable pools sees NO models.
+ *
+ * Pure function — no I/O, easily unit-tested.
+ */
+export function filterModelsToQuotaPools<T extends { id: string }>(
+  models: T[],
+  poolSlugs: string[]
+): T[] {
+  if (poolSlugs.length === 0) return [];
+  const slugSet = new Set(poolSlugs);
+  return models.filter((m) => {
+    if (!isQuotaModelName(m.id)) return false;
+    const parsed = parseQuotaModelName(m.id);
+    return parsed !== null && slugSet.has(parsed.poolSlug);
+  });
+}
+
 /**
  * Delete ALL `quotaShared-*` combos that belong to the given pool.
  *
diff --git a/tests/unit/quota-catalog-filter.test.ts b/tests/unit/quota-catalog-filter.test.ts
new file mode 100644
index 0000000000..488120d2db
--- /dev/null
+++ b/tests/unit/quota-catalog-filter.test.ts
@@ -0,0 +1,56 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+import { filterModelsToQuotaPools } from "../../src/lib/quota/quotaCombos.js";
+
+describe("filterModelsToQuotaPools", () => {
+  const models = [
+    { id: "quotaShared-times-codex/gpt-5.5" },
+    { id: "quotaShared-times-codex/gpt-5.4" },
+    { id: "cx/gpt-5.5" },
+    { id: "quotaShared-other-codex/m" },
+  ];
+
+  it("returns only quotaShared-* entries whose poolSlug is in the given pool slugs", () => {
+    const result = filterModelsToQuotaPools(models, ["times"]);
+    assert.deepEqual(result, [
+      { id: "quotaShared-times-codex/gpt-5.5" },
+      { id: "quotaShared-times-codex/gpt-5.4" },
+    ]);
+  });
+
+  it("returns empty array when poolSlugs is empty (fail-closed)", () => {
+    const result = filterModelsToQuotaPools(models, []);
+    assert.deepEqual(result, []);
+  });
+
+  it("returns empty array when no quota models are present in the list", () => {
+    const plainModels = [{ id: "cx/gpt-5.5" }, { id: "openai/gpt-4o" }];
+    const result = filterModelsToQuotaPools(plainModels, ["times"]);
+    assert.deepEqual(result, []);
+  });
+
+  it("matches multiple pool slugs simultaneously", () => {
+    const result = filterModelsToQuotaPools(models, ["times", "other"]);
+    assert.deepEqual(result, [
+      { id: "quotaShared-times-codex/gpt-5.5" },
+      { id: "quotaShared-times-codex/gpt-5.4" },
+      { id: "quotaShared-other-codex/m" },
+    ]);
+  });
+
+  it("preserves extra fields on model entries (generic T extends { id })", () => {
+    const richModels = [
+      { id: "quotaShared-times-cx/gpt-5.5", object: "model", owned_by: "combo" },
+      { id: "cx/gpt-5.5", object: "model", owned_by: "cx" },
+    ];
+    const result = filterModelsToQuotaPools(richModels, ["times"]);
+    assert.deepEqual(result, [
+      { id: "quotaShared-times-cx/gpt-5.5", object: "model", owned_by: "combo" },
+    ]);
+  });
+
+  it("does not match a model from a different pool when only one slug is provided", () => {
+    const result = filterModelsToQuotaPools(models, ["other"]);
+    assert.deepEqual(result, [{ id: "quotaShared-other-codex/m" }]);
+  });
+});