diff --git a/packages/catalog/CHANGELOG.md b/packages/catalog/CHANGELOG.md
index 3e5f80841..0ea3cb284 100644
--- a/packages/catalog/CHANGELOG.md
+++ b/packages/catalog/CHANGELOG.md
@@ -143,6 +143,10 @@
 - Requested `reasoning.encrypted_content` on first-party xAI Responses calls (`xai` and `xai-oauth`) via the `include` parameter.
 - Replayed xAI encrypted reasoning items on later Responses turns instead of stripping `type: "reasoning"` history.
 
+### Fixed
+
+- Invalidated stale paid-xAI model-cache rows written under Chat Completions so the Responses migration takes effect immediately instead of waiting for TTL expiry.
+
 ## [17.2.5] - 2026-08-03
 
 ### Fixed
diff --git a/packages/catalog/src/provider-models/openai-compat.ts b/packages/catalog/src/provider-models/openai-compat.ts
index 59dd61514..8c9fe3384 100644
--- a/packages/catalog/src/provider-models/openai-compat.ts
+++ b/packages/catalog/src/provider-models/openai-compat.ts
@@ -1258,7 +1258,15 @@ export interface XaiModelManagerConfig {
 }
 
 export function xaiModelManagerOptions(config?: XaiModelManagerConfig): ModelManagerOptions<"openai-responses"> {
-	return createSimpleOpenAIResponsesOptions("xai", "https://api.x.ai/v1", config);
+	return {
+		...createSimpleOpenAIResponsesOptions("xai", "https://api.x.ai/v1", config),
+		// Completions → Responses migration: a fresh authoritative cache written
+		// by the old resolver stores `api: "openai-completions"` for these ids.
+		// Without a drop list, `online-if-uncached` skips the network and
+		// `mergeDynamicModel` lets the cached api win over the new static
+		// Responses entries until TTL expiry.
+		dropCachedModelIdsOnStaticMismatch: getBundledModels("xai").map(model => model.id),
+	};
 }
 
 export interface XaiOAuthModelManagerConfig {
diff --git a/packages/catalog/test/xai-api-key-responses.test.ts b/packages/catalog/test/xai-api-key-responses.test.ts
index 5f605eb5c..c11849cec 100644
--- a/packages/catalog/test/xai-api-key-responses.test.ts
+++ b/packages/catalog/test/xai-api-key-responses.test.ts
@@ -1,7 +1,37 @@
 import { describe, expect, it } from "bun:test";
+import * as fs from "node:fs/promises";
+import * as os from "node:os";
+import * as path from "node:path";
+import { resolveProviderModels } from "@oh-my-pi/pi-catalog/model-manager";
 import { getBundledModels } from "@oh-my-pi/pi-catalog/models";
 import { CATALOG_PROVIDERS } from "@oh-my-pi/pi-catalog/provider-models/descriptors";
 import { xaiModelManagerOptions } from "@oh-my-pi/pi-catalog/provider-models/openai-compat";
+import type { ModelSpec } from "@oh-my-pi/pi-catalog/types";
+
+const XAI_RESPONSES_SPEC: ModelSpec<"openai-responses"> = {
+	id: "grok-4.5",
+	name: "Grok 4.5",
+	api: "openai-responses",
+	provider: "xai",
+	baseUrl: "https://api.x.ai/v1",
+	reasoning: true,
+	input: ["text", "image"],
+	cost: { input: 2, output: 6, cacheRead: 0.3, cacheWrite: 0 },
+	contextWindow: 500_000,
+	maxTokens: 500_000,
+};
+const XAI_COMPLETIONS_SPEC: ModelSpec<"openai-completions"> = {
+	id: "grok-4.5",
+	name: "Grok 4.5",
+	api: "openai-completions",
+	provider: "xai",
+	baseUrl: "https://api.x.ai/v1",
+	reasoning: true,
+	input: ["text", "image"],
+	cost: { input: 2, output: 6, cacheRead: 0.3, cacheWrite: 0 },
+	contextWindow: 500_000,
+	maxTokens: 500_000,
+};
 
 describe("paid xai (XAI_API_KEY) Responses contract", () => {
 	it("registers xai on the catalog Responses discovery path", () => {
@@ -12,6 +42,8 @@ describe("paid xai (XAI_API_KEY) Responses contract", () => {
 		const options = xaiModelManagerOptions({ apiKey: "test-key" });
 		expect(options.providerId).toBe("xai");
 		expect(options.fetchDynamicModels, "live /v1/models overlay").toBeTypeOf("function");
+		expect(options.dropCachedModelIdsOnStaticMismatch).toEqual(getBundledModels("xai").map(model => model.id));
+		expect(options.dropCachedModelIdsOnStaticMismatch).toContain("grok-4.5");
 	});
 
 	it("bundles every paid xai chat model on openai-responses", () => {
@@ -22,4 +54,50 @@ describe("paid xai (XAI_API_KEY) Responses contract", () => {
 			expect(model.baseUrl).toBe("https://api.x.ai/v1");
 		}
 	});
+
+	it("drops stale Chat Completions cache rows so Responses takes effect immediately", async () => {
+		const tempDir = await fs.mkdtemp(path.join(os.tmpdir(), "pi-catalog-xai-completions-cache-"));
+		const dbPath = path.join(tempDir, "models.db");
+		try {
+			await resolveProviderModels(
+				{
+					providerId: "xai",
+					staticModels: [XAI_COMPLETIONS_SPEC],
+					fetchDynamicModels: async () => [XAI_COMPLETIONS_SPEC],
+					cacheDbPath: dbPath,
+				},
+				"online",
+			);
+
+			let fetches = 0;
+			const migrated = await resolveProviderModels(
+				{
+					...xaiModelManagerOptions(),
+					staticModels: [XAI_RESPONSES_SPEC],
+					cacheDbPath: dbPath,
+					fetchDynamicModels: async () => {
+						fetches += 1;
+						return [XAI_RESPONSES_SPEC];
+					},
+				},
+				"online-if-uncached",
+			);
+
+			expect(fetches).toBe(1);
+			expect(migrated.models.find(model => model.id === "grok-4.5")?.api).toBe("openai-responses");
+
+			const offline = await resolveProviderModels(
+				{
+					...xaiModelManagerOptions(),
+					staticModels: [XAI_RESPONSES_SPEC],
+					cacheDbPath: dbPath,
+					fetchDynamicModels: async () => null,
+				},
+				"offline",
+			);
+			expect(offline.models.find(model => model.id === "grok-4.5")?.api).toBe("openai-responses");
+		} finally {
+			await fs.rm(tempDir, { recursive: true, force: true });
+		}
+	});
 });