fix(catalog): map aliased Gemini Flash minimal to LOW on Cloud Code Assist

When a collapsed Gemini 3.6/3.7 Flash family routes user minimal onto the
same Cloud Code Assist wire id as low, emit thinkingLevel LOW. Those -low
SKUs reject MINIMAL with HTTP 400.

packages/ai/CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## [Unreleased]
 
+
+### Fixed
+
+- Cloud Code Assist Gemini 3.6/3.7 Flash requests at `minimal` now send `thinkingLevel: LOW` on the aliased `-low` SKU instead of `MINIMAL`, which the API rejects with HTTP 400.
+
 ## [17.3.7] - 2026-08-17
 
 ### Changed

packages/ai/src/stream.ts

@@ -2149,7 +2149,7 @@ function mapOptionsForApi<TApi extends Api>(
 					serviceTier: options?.serviceTier,
 					thinking: {
 						enabled: true,
-						level: mapEffortToGoogleThinkingLevel(effort),
+						level: mapEffortToGoogleThinkingLevel(effort, googleModel),
 					},
 					hideThinkingSummary: options?.hideThinkingSummary,
 					toolChoice: mapGoogleToolChoice(options?.toolChoice),
@@ -2182,7 +2182,7 @@ function mapOptionsForApi<TApi extends Api>(
 						requestModelId: resolveWireModelId(model, effort),
 						thinking: {
 							enabled: true,
-							level: mapEffortToGoogleThinkingLevel(effort),
+							level: mapEffortToGoogleThinkingLevel(effort, model),
 						},
 						hideThinkingSummary: options?.hideThinkingSummary,
 						toolChoice,
@@ -2254,7 +2254,7 @@ function mapOptionsForApi<TApi extends Api>(
 					serviceTier: options?.serviceTier,
 					thinking: {
 						enabled: true,
-						level: mapEffortToGoogleThinkingLevel(effort),
+						level: mapEffortToGoogleThinkingLevel(effort, model),
 					},
 					hideThinkingSummary: options?.hideThinkingSummary,
 					toolChoice: mapGoogleToolChoice(options?.toolChoice),

packages/ai/test/google-gemini-cli-3x-thinking.test.ts

@@ -11,6 +11,7 @@ interface GeminiCliThinkingConfig {
 }
 
 interface CapturedRequestBody {
+	model?: string;
 	request?: {
 		generationConfig?: {
 			thinkingConfig?: GeminiCliThinkingConfig;
@@ -138,4 +139,47 @@ describe("google-gemini-cli Gemini 3.x thinking mapping", () => {
 		expect(thinking?.thinkingLevel).toBeUndefined();
 		expect(thinking?.thinkingBudget).toBeDefined();
 	});
+
+	it("sends LOW not MINIMAL when gemini-3.7-flash minimal aliases the -low SKU", async () => {
+		let requestBody: string | undefined;
+		const fetchMock = createFetchMock(body => {
+			requestBody = body;
+		});
+
+		const model = buildModel({
+			id: "gemini-3.7-flash",
+			name: "Gemini 3.7 Flash",
+			api: "google-gemini-cli",
+			provider: "google-antigravity",
+			baseUrl: "https://daily-cloudcode-pa.googleapis.com",
+			reasoning: true,
+			thinking: {
+				mode: "google-level",
+				efforts: [Effort.Minimal, Effort.Low, Effort.Medium, Effort.High],
+				requiresEffort: true,
+				effortRouting: {
+					[Effort.Minimal]: "gemini-3.7-flash-low",
+					[Effort.Low]: "gemini-3.7-flash-low",
+					[Effort.Medium]: "gemini-3.7-flash-medium",
+					[Effort.High]: "gemini-3.7-flash-high",
+				},
+			},
+			input: ["text", "image"],
+			cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+			contextWindow: 1_048_576,
+			maxTokens: 65_536,
+		});
+
+		const stream = streamSimple(model, context, {
+			apiKey: JSON.stringify({ token: "token", projectId: "proj-123" }),
+			reasoning: Effort.Minimal,
+			fetch: fetchMock,
+		});
+		await stream.result();
+
+		const parsed = JSON.parse(requestBody ?? "{}") as CapturedRequestBody;
+		expect(parsed.model).toBe("gemini-3.7-flash-low");
+		expect(parsed.request?.generationConfig?.thinkingConfig?.thinkingLevel).toBe("LOW");
+	});
+
 });

packages/catalog/CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## [Unreleased]
 
+
+### Fixed
+
+- Cloud Code Assist Gemini 3.6/3.7 Flash no longer maps user `minimal` to wire `thinkingLevel: MINIMAL` when that effort is aliased onto the `-low` SKU. The request now sends `LOW`, which those SKUs accept.
+
 ## [17.3.6] - 2026-08-17
 
 ### Changed

packages/catalog/src/model-thinking.ts

@@ -796,11 +796,22 @@ export function requireSupportedEffort<TApi extends Api>(model: ApiModel<TApi>,
 	return effort;
 }
 
-/** Maps a normalized thinking effort to Google's `thinkingLevel` enum values. */
-export function mapEffortToGoogleThinkingLevel(effort: Effort): "MINIMAL" | "LOW" | "MEDIUM" | "HIGH" {
+/** Maps a normalized thinking effort to Google's `thinkingLevel` enum values.
+ *  When a collapsed family routes `minimal` onto the same wire id as `low`
+ *  (Antigravity Gemini 3.6/3.7 Flash), emit `LOW` — Cloud Code Assist rejects
+ *  `MINIMAL` on those `-low` SKUs. */
+export function mapEffortToGoogleThinkingLevel<TApi extends Api>(
+	effort: Effort,
+	model?: ApiModel<TApi>,
+): "MINIMAL" | "LOW" | "MEDIUM" | "HIGH" {
+	if (effort === Effort.Minimal) {
+		const routing = model?.thinking?.effortRouting;
+		if (routing?.[Effort.Minimal] && routing[Effort.Minimal] === routing[Effort.Low]) {
+			return "LOW";
+		}
+		return "MINIMAL";
+	}
 	switch (effort) {
-		case Effort.Minimal:
-			return "MINIMAL";
 		case Effort.Low:
 			return "LOW";
 		case Effort.Medium:

packages/catalog/test/model-thinking.test.ts

@@ -360,6 +360,29 @@ describe("model thinking derivation", () => {
 		expect(() => requireSupportedEffort(model, Effort.Medium)).toThrow(/not supported/);
 	});
 
+	it("maps minimal to LOW when a collapsed family aliases it onto the low wire id", () => {
+		const model = createModel({
+			id: "gemini-3.7-flash",
+			api: "google-gemini-cli",
+			provider: "google-antigravity",
+			thinking: {
+				mode: "google-level",
+				efforts: [Effort.Minimal, Effort.Low, Effort.Medium, Effort.High],
+				requiresEffort: true,
+				effortRouting: {
+					[Effort.Minimal]: "gemini-3.7-flash-low",
+					[Effort.Low]: "gemini-3.7-flash-low",
+					[Effort.Medium]: "gemini-3.7-flash-medium",
+					[Effort.High]: "gemini-3.7-flash-high",
+				},
+			},
+		});
+		expect(mapEffortToGoogleThinkingLevel(Effort.Minimal, model)).toBe("LOW");
+		expect(mapEffortToGoogleThinkingLevel(Effort.Low, model)).toBe("LOW");
+		expect(mapEffortToGoogleThinkingLevel(Effort.Minimal)).toBe("MINIMAL");
+	});
+
+
 	it("bakes requiresEffort for Gemini 3.x on any provider and backfills explicit metadata", () => {
 		// Derivation: aggregator-hosted Gemini 3.5 gets the flag, 2.5 does not.
 		const openRouterFlash = createModel({