fix(providers): made gemini search model configurable

Added providers.webSearchGeminiModel and GEMINI_SEARCH_MODEL so Gemini web_search requests use a selected grounding model while keeping gemini-2.5-flash as the fallback.

Covered OAuth, Developer API, and missing modelVersion fallback paths in Gemini web search tests.

Fixes #4312

docs/settings.md

@@ -597,6 +597,7 @@ providers:
   webSearch: auto
   image: auto
   fetch: auto
+  webSearchGeminiModel: gemini-2.5-flash
   tinyModel: online
   tinyModelDevice: default
   tinyModelDtype: default
@@ -621,6 +622,7 @@ searxng:
 | Key | Type | Default | Values / notes |
 |---|---|---|---|
 | `providers.webSearch` | enum | `auto` | `auto` plus the configured search providers (`perplexity`, `gemini`, `anthropic`, `codex`, `zai`, `exa`, `jina`, `kagi`, `tavily`, `brave`, `kimi`, `parallel`, `synthetic`, `searxng`). |
+| `providers.webSearchGeminiModel` | string | _(unset)_ | Gemini model ID for Google Search grounding when `web_search` uses Gemini; defaults to `gemini-2.5-flash`, overridden by `GEMINI_SEARCH_MODEL`. |
 | `providers.image` | enum | `auto` | `auto`, `openai`, `antigravity`, `xai`, `gemini`, `openrouter`. |
 | `providers.fetch` | enum | `auto` | `auto`, `native`, `trafilatura`, `lynx`, `parallel`, `jina`. |
 | `providers.tinyModel` | enum | `online` | `online` or a local model (`lfm2-350m`, `qwen3-0.6b`, `gemma-270m`, `qwen2.5-0.5b`, `lfm2-700m`). |

docs/tools/web_search.md

@@ -104,8 +104,9 @@ Streaming: none. `WebSearchTool.execute()` forwards its `AbortSignal` into `exec
     - `num_search_results` controls upstream API breadth only in API-key mode. `limit` is preserved separately as `num_results` and slices returned `sources` after parsing in both auth modes.
     - Output may include `answer`, `sources`, `citations`, `usage`, `model`, `requestId`, `authMode`.
   - **Gemini** — `packages/coding-agent/src/web/search/providers/gemini.ts`
-    - Availability: OAuth credentials in `agent.db` for `google-gemini-cli` or `google-antigravity`.
+    - Availability: OAuth credentials in `agent.db` for `google-gemini-cli` / `google-antigravity`, or a Google Developer API key.
     - Querying: SSE `streamGenerateContent` call with Google Search grounding enabled. Antigravity auth tries two fallback endpoints and retries `401/403/400 invalid auth` once after token refresh; `429/5xx` retry with exponential backoff and server-provided retry delay, capped by a `5 * 60 * 1000` ms rate-limit budget.
+    - Model: `providers.webSearchGeminiModel` selects the Gemini grounding model; `GEMINI_SEARCH_MODEL` overrides it. Defaults to `gemini-2.5-flash`.
     - `max_tokens` and `temperature` pass through as `generationConfig.maxOutputTokens` / `generationConfig.temperature`.
     - `limit` and `num_search_results` are collapsed together before dispatch.
     - Output may include `answer`, `sources`, `citations`, `searchQueries`, `usage`, `model`.

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed Gemini web_search to honor `providers.webSearchGeminiModel` / `GEMINI_SEARCH_MODEL` for both OAuth and Developer API grounding requests. ([#4312](https://github.com/can1357/oh-my-pi/issues/4312))
+
 ## [16.3.1] - 2026-07-02
 
 ### Breaking Changes

packages/coding-agent/src/config/settings-schema.ts

@@ -4337,6 +4337,16 @@ export const SETTINGS_SCHEMA = {
 			description: "Providers that web_search should never use, even as fallbacks",
 		},
 	},
+	"providers.webSearchGeminiModel": {
+		type: "string",
+		default: undefined,
+		ui: {
+			tab: "providers",
+			group: "Services",
+			label: "Gemini web_search model",
+			description: "Model ID for Gemini Google Search grounding. Defaults to gemini-2.5-flash.",
+		},
+	},
 	"providers.antigravityEndpoint": {
 		type: "enum",
 		values: ["auto", "production", "sandbox"] as const,

packages/coding-agent/src/web/search/index.ts

@@ -159,6 +159,13 @@ async function executeSearch(
 		antigravityEndpointMode = undefined;
 	}
 
+	let geminiModel: string | undefined;
+	try {
+		geminiModel = settings.get("providers.webSearchGeminiModel");
+	} catch {
+		geminiModel = undefined;
+	}
+
 	const failures: Array<{ provider: SearchProvider; error: unknown }> = [];
 	let lastProvider = providers[0];
 	for (const provider of providers) {
@@ -176,6 +183,7 @@ async function executeSearch(
 				authStorage,
 				sessionId,
 				antigravityEndpointMode,
+				geminiModel,
 			});
 
 			if (!hasRenderableSearchContent(response)) {

packages/coding-agent/src/web/search/providers/base.ts

@@ -52,6 +52,7 @@ export interface SearchParams {
 	 */
 	sessionId?: string;
 	antigravityEndpointMode?: "auto" | "production" | "sandbox";
+	geminiModel?: string;
 }
 
 /** Base class for web search providers. */

packages/coding-agent/src/web/search/providers/gemini.ts

@@ -33,6 +33,13 @@ const MAX_RETRIES = 3;
 const BASE_DELAY_MS = 1000;
 const RATE_LIMIT_BUDGET_MS = 5 * 60 * 1000;
 
+function resolveGeminiSearchModel(configuredModel: string | undefined): string {
+	const envModel = Bun.env.GEMINI_SEARCH_MODEL?.trim();
+	if (envModel) return envModel;
+	const model = configuredModel?.trim();
+	return model || DEFAULT_MODEL;
+}
+
 const GEMINI_PROVIDERS = ["google-gemini-cli", "google-antigravity"] as const;
 type GeminiProviderId = (typeof GEMINI_PROVIDERS)[number];
 
@@ -55,6 +62,7 @@ export interface GeminiSearchParams extends GeminiToolParams {
 	sessionId?: string;
 	fetch?: FetchImpl;
 	antigravityEndpointMode?: "auto" | "production" | "sandbox";
+	geminiModel?: string;
 }
 
 export function buildGeminiRequestTools(params: GeminiToolParams): Array<Record<string, Record<string, unknown>>> {
@@ -160,13 +168,16 @@ interface CloudCodeResponseChunk {
 	response?: GeminiModelResponse;
 }
 
-async function parseGeminiSearchStream(body: ReadableStream<Uint8Array>): Promise<GeminiSearchResult> {
+async function parseGeminiSearchStream(
+	body: ReadableStream<Uint8Array>,
+	fallbackModel: string,
+): Promise<GeminiSearchResult> {
 	const answerParts: string[] = [];
 	const sources: SearchSource[] = [];
 	const citations: SearchCitation[] = [];
 	const searchQueries: string[] = [];
 	const seenUrls = new Set<string>();
-	let model = DEFAULT_MODEL;
+	let model = fallbackModel;
 	let usage: { inputTokens: number; outputTokens: number; totalTokens: number } | undefined;
 
 	const reader = body.getReader();
@@ -287,6 +298,7 @@ async function parseGeminiSearchStream(body: ReadableStream<Uint8Array>): Promis
  */
 async function callGeminiSearch(
 	auth: GeminiAuth,
+	model: string,
 	query: string,
 	systemPrompt: string | undefined,
 	maxOutputTokens: number | undefined,
@@ -330,7 +342,7 @@ async function callGeminiSearch(
 
 	const requestBody: Record<string, unknown> = {
 		project: auth.projectId,
-		model: DEFAULT_MODEL,
+		model,
 		request: {
 			contents: [
 				{
@@ -414,11 +426,12 @@ async function callGeminiSearch(
 		throw new SearchProviderError("gemini", "Gemini API returned no response body", 500);
 	}
 
-	return parseGeminiSearchStream(response.body);
+	return parseGeminiSearchStream(response.body, model);
 }
 
 async function callGeminiDeveloperSearch(
 	apiKey: string,
+	model: string,
 	query: string,
 	systemPrompt: string | undefined,
 	maxOutputTokens: number | undefined,
@@ -455,7 +468,7 @@ async function callGeminiDeveloperSearch(
 	}
 
 	const response = await fetchWithRetry(
-		() => `${DEVELOPER_API_ENDPOINT}/models/${DEFAULT_MODEL}:streamGenerateContent?alt=sse`,
+		() => `${DEVELOPER_API_ENDPOINT}/models/${model}:streamGenerateContent?alt=sse`,
 		{
 			method: "POST",
 			headers: {
@@ -487,13 +500,14 @@ async function callGeminiDeveloperSearch(
 		throw new SearchProviderError("gemini", "Gemini API returned no response body", 500);
 	}
 
-	return parseGeminiSearchStream(response.body);
+	return parseGeminiSearchStream(response.body, model);
 }
 
 /**
  * Executes a web search using Google Gemini with Google Search grounding.
  */
 export async function searchGemini(params: GeminiSearchParams): Promise<SearchResponse> {
+	const selectedModel = resolveGeminiSearchModel(params.geminiModel);
 	const seed = await findGeminiAuth(params.authStorage, params.sessionId, params.signal);
 	let result: GeminiSearchResult;
 
@@ -513,6 +527,7 @@ export async function searchGemini(params: GeminiSearchParams): Promise<SearchRe
 						projectId: access.projectId ?? seed.projectId,
 						isAntigravity,
 					},
+					selectedModel,
 					params.query,
 					params.system_prompt,
 					params.max_output_tokens,
@@ -539,6 +554,7 @@ export async function searchGemini(params: GeminiSearchParams): Promise<SearchRe
 		}
 		result = await callGeminiDeveloperSearch(
 			apiKey,
+			selectedModel,
 			params.query,
 			params.system_prompt,
 			params.max_output_tokens,
@@ -596,6 +612,7 @@ export class GeminiProvider extends SearchProvider {
 			authStorage: params.authStorage,
 			sessionId: params.sessionId,
 			fetch: params.fetch,
+			geminiModel: params.geminiModel,
 		});
 	}
 }

packages/coding-agent/test/tools/web-search-gemini.test.ts

@@ -7,6 +7,9 @@ const SSE_RESPONSE =
 	'data: {"response":{"candidates":[{"content":{"role":"model","parts":[{"text":"Gemini answer"}]}}],"modelVersion":"gemini-2.5-flash"}}\n\n';
 const DEVELOPER_SSE_RESPONSE =
 	'data: {"candidates":[{"content":{"role":"model","parts":[{"text":"Developer answer"}]},"groundingMetadata":{"webSearchQueries":["latest Bun version"],"groundingChunks":[{"web":{"uri":"https://bun.sh","title":"Bun"}}],"groundingSupports":[{"segment":{"text":"Developer answer"},"groundingChunkIndices":[0]}]}}],"usageMetadata":{"promptTokenCount":3,"candidatesTokenCount":4,"totalTokenCount":7},"modelVersion":"gemini-2.5-flash"}\n\n';
+const DEVELOPER_SSE_RESPONSE_WITHOUT_MODEL =
+	'data: {"candidates":[{"content":{"role":"model","parts":[{"text":"Developer answer"}]},"groundingMetadata":{"webSearchQueries":["latest Bun version"],"groundingChunks":[{"web":{"uri":"https://bun.sh","title":"Bun"}}],"groundingSupports":[{"segment":{"text":"Developer answer"},"groundingChunkIndices":[0]}]}}],"usageMetadata":{"promptTokenCount":3,"candidatesTokenCount":4,"totalTokenCount":7}}\n\n';
+const ORIGINAL_GEMINI_SEARCH_MODEL = Bun.env.GEMINI_SEARCH_MODEL;
 
 type CapturedRequest = {
 	url: string;
@@ -64,6 +67,11 @@ describe("searchGemini tools serialization", () => {
 
 	afterEach(() => {
 		capturedRequest = null;
+		if (ORIGINAL_GEMINI_SEARCH_MODEL === undefined) {
+			delete Bun.env.GEMINI_SEARCH_MODEL;
+		} else {
+			Bun.env.GEMINI_SEARCH_MODEL = ORIGINAL_GEMINI_SEARCH_MODEL;
+		}
 	});
 
 	function makeParams(query: string) {
@@ -102,6 +110,48 @@ describe("searchGemini tools serialization", () => {
 			usage: { inputTokens: 3, outputTokens: 4, totalTokens: 7 },
 		});
 	});
+
+	it("uses configured developer API model and reports it when modelVersion is absent", async () => {
+		const fetchMock = mockGeminiFetch(DEVELOPER_SSE_RESPONSE_WITHOUT_MODEL);
+		const response = await searchGemini({
+			...makeParams("developer api configured"),
+			authStorage: apiKeyAuthStorage,
+			geminiModel: "gemini-3.5-flash",
+			fetch: fetchMock,
+		});
+
+		expect(capturedRequest?.url).toBe(
+			"https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:streamGenerateContent?alt=sse",
+		);
+		expect(response.model).toBe("gemini-3.5-flash");
+	});
+
+	it("uses configured OAuth model in the Cloud Code request body", async () => {
+		const fetchMock = mockGeminiFetch();
+		await searchGemini({
+			...makeParams("oauth configured"),
+			geminiModel: "gemini-3.5-flash",
+			fetch: fetchMock,
+		});
+
+		expect(capturedRequest?.body).toMatchObject({
+			model: "gemini-3.5-flash",
+		});
+	});
+
+	it("lets GEMINI_SEARCH_MODEL override the configured Gemini model", async () => {
+		Bun.env.GEMINI_SEARCH_MODEL = "gemini-2.5-pro";
+		const fetchMock = mockGeminiFetch();
+		await searchGemini({
+			...makeParams("env configured"),
+			geminiModel: "gemini-3.5-flash",
+			fetch: fetchMock,
+		});
+
+		expect(capturedRequest?.body).toMatchObject({
+			model: "gemini-2.5-pro",
+		});
+	});
 	it("sends default googleSearch tool when no passthrough payloads are provided", async () => {
 		const fetchMock = mockGeminiFetch();
 		await searchGemini({ ...makeParams("default tools"), fetch: fetchMock });
@@ -110,6 +160,9 @@ describe("searchGemini tools serialization", () => {
 		expect(capturedRequest?.body?.request).toMatchObject({
 			tools: [{ googleSearch: {} }],
 		});
+		expect(capturedRequest?.body).toMatchObject({
+			model: "gemini-2.5-flash",
+		});
 	});
 
 	it("passes through googleSearch payload into googleSearch tool", async () => {