diff --git a/packages/ai/CHANGELOG.md b/packages/ai/CHANGELOG.md
index fe3aa47fa..996bc2d4e 100644
--- a/packages/ai/CHANGELOG.md
+++ b/packages/ai/CHANGELOG.md
@@ -21,6 +21,7 @@
 ### Fixed
 
 - Fixed expired OAuth handling so provider-level paths no longer attempt direct token refresh calls for expired credentials and instead rely on `AuthStorage` for rotation
+- Fixed `google-gemini-cli` / `google-antigravity` aborting heavy reasoning runs with "Provider stream timed out while waiting for the first event" before the upstream had a chance to emit its first SSE frame. Cloud Code Assist routinely takes >100s on Gemini 3.x Pro at high thinking levels; the lazy-stream wrapper now floors the first-event watchdog at 5 minutes for these two providers when neither `StreamOptions.streamFirstEventTimeoutMs` nor `PI_STREAM_FIRST_EVENT_TIMEOUT_MS` pins a value. Other providers keep the 100s default. Internally, `getStreamIdleTimeoutMs` and `getStreamFirstEventTimeoutMs` now accept an optional per-provider `fallbackMs` so other slow-first-token providers can opt into the same widening without leaking through to the global default.
 - Fixed Claude Opus 4.7 on Amazon Bedrock streaming no reasoning output (and appearing to hang on long reasoning runs) because Anthropic silently switched the adaptive-thinking display default to `"omitted"`. The Bedrock provider now sends `thinking.display = "summarized"` by default on Opus 4.7+ adaptive models and on budget-based Claude models, mirroring the existing direct-Anthropic behavior. `BedrockOptions.thinkingDisplay` (`"summarized" | "omitted"`) is exposed for callers that want to opt out, and `hideThinkingSummary` now wires through to the Bedrock case ([#1373](https://github.com/can1357/oh-my-pi/issues/1373)).
 
 ## [15.3.2] - 2026-05-25
diff --git a/packages/ai/src/providers/register-builtins.ts b/packages/ai/src/providers/register-builtins.ts
index ab463f7d6..cb47fe4c7 100644
--- a/packages/ai/src/providers/register-builtins.ts
+++ b/packages/ai/src/providers/register-builtins.ts
@@ -166,19 +166,47 @@ function hasFinalResult(
 	return typeof (source as { result?: unknown }).result === "function";
 }
 
+/**
+ * Per-provider default overrides for the lazy stream watchdogs. These widen the
+ * floor used when neither caller option nor env var pins a value. The env vars
+ * (`PI_STREAM_FIRST_EVENT_TIMEOUT_MS`, `PI_STREAM_IDLE_TIMEOUT_MS`) still take
+ * precedence; `StreamOptions.streamFirstEventTimeoutMs` / `streamIdleTimeoutMs`
+ * still trump everything.
+ */
+interface LazyStreamLimits {
+	defaultFirstEventTimeoutMs?: number;
+	defaultIdleTimeoutMs?: number;
+}
+
+/**
+ * Cloud Code Assist (google-gemini-cli / google-antigravity) routinely takes
+ * longer than the global 100s default to emit its first SSE event when serving
+ * the heavier Gemini 3.x Pro tiers at high thinking levels. Bump the first-event
+ * floor to five minutes so duke et al. stop seeing spurious "stream timed out
+ * while waiting for the first event" aborts on legitimate cold reasoning starts.
+ * The steady-state idle watchdog stays on the global default since the upstream
+ * emits thinking tokens frequently once it gets going.
+ */
+const GOOGLE_GEMINI_CLI_LAZY_STREAM_LIMITS: LazyStreamLimits = {
+	defaultFirstEventTimeoutMs: 300_000,
+};
+
 function forwardStream<TApi extends Api>(
 	target: EventStreamImpl,
 	source: AsyncIterable<AssistantMessageEvent>,
 	model: Model<TApi>,
 	options: OptionsForApi<TApi>,
 	abortTracker: AbortSourceTracker,
+	limits?: LazyStreamLimits,
 ): void {
 	(async () => {
 		try {
-			const idleTimeoutMs = options.streamIdleTimeoutMs ?? getStreamIdleTimeoutMs();
+			const idleTimeoutMs = options.streamIdleTimeoutMs ?? getStreamIdleTimeoutMs(limits?.defaultIdleTimeoutMs);
 			const watchedSource = iterateWithIdleTimeout(source, {
 				idleTimeoutMs,
-				firstItemTimeoutMs: options.streamFirstEventTimeoutMs ?? getStreamFirstEventTimeoutMs(idleTimeoutMs),
+				firstItemTimeoutMs:
+					options.streamFirstEventTimeoutMs ??
+					getStreamFirstEventTimeoutMs(idleTimeoutMs, limits?.defaultFirstEventTimeoutMs),
 				errorMessage: LAZY_STREAM_IDLE_TIMEOUT_ERROR,
 				firstItemErrorMessage: LAZY_STREAM_FIRST_EVENT_TIMEOUT_ERROR,
 				onIdle: () => abortTracker.abortLocally(new Error(LAZY_STREAM_IDLE_TIMEOUT_ERROR)),
@@ -241,6 +269,7 @@ function createLazyLoadErrorMessage<TApi extends Api>(
 
 function createLazyStream<TApi extends Api>(
 	loadModule: () => Promise<LazyProviderModule<TApi>>,
+	limits?: LazyStreamLimits,
 ): (model: Model<TApi>, context: Context, options: OptionsForApi<TApi>) => EventStreamImpl {
 	return (model, context, options) => {
 		const outer = new EventStreamImpl();
@@ -251,7 +280,7 @@ function createLazyStream<TApi extends Api>(
 				const abortTracker = createAbortSourceTracker(streamOptions.signal);
 				const providerOptions = { ...streamOptions, signal: abortTracker.requestSignal } as OptionsForApi<TApi>;
 				const inner = module.stream(model, context, providerOptions);
-				forwardStream(outer, inner, model, streamOptions, abortTracker);
+				forwardStream(outer, inner, model, streamOptions, abortTracker, limits);
 			})
 			.catch(error => {
 				const message = createLazyLoadErrorMessage(model, error);
@@ -369,7 +398,10 @@ function loadBedrockProviderModule(): Promise<LazyProviderModule<"bedrock-conver
 export const streamAnthropic = createLazyStream(loadAnthropicProviderModule);
 export const streamAzureOpenAIResponses = createLazyStream(loadAzureOpenAIResponsesProviderModule);
 export const streamGoogle = createLazyStream(loadGoogleProviderModule);
-export const streamGoogleGeminiCli = createLazyStream(loadGoogleGeminiCliProviderModule);
+export const streamGoogleGeminiCli = createLazyStream(
+	loadGoogleGeminiCliProviderModule,
+	GOOGLE_GEMINI_CLI_LAZY_STREAM_LIMITS,
+);
 export const streamGoogleVertex = createLazyStream(loadGoogleVertexProviderModule);
 export const streamOpenAICodexResponses = createLazyStream(loadOpenAICodexResponsesProviderModule);
 export const streamOpenAICompletions = createLazyStream(loadOpenAICompletionsProviderModule);
diff --git a/packages/ai/src/utils/idle-iterator.ts b/packages/ai/src/utils/idle-iterator.ts
index 648616972..1c0ab903c 100644
--- a/packages/ai/src/utils/idle-iterator.ts
+++ b/packages/ai/src/utils/idle-iterator.ts
@@ -16,12 +16,13 @@ function normalizeIdleTimeoutMs(value: string | undefined, fallback: number): nu
  *
  * `PI_OPENAI_STREAM_IDLE_TIMEOUT_MS` is accepted as a backward-compatible alias.
  * Set `PI_STREAM_IDLE_TIMEOUT_MS=0` to disable the watchdog.
+ *
+ * Providers that legitimately stream much slower than the global default can pass
+ * `fallbackMs` to widen the floor used when neither env var nor caller option is set.
+ * Caller options still take precedence; env overrides still trump the fallback.
  */
-export function getStreamIdleTimeoutMs(): number | undefined {
-	return normalizeIdleTimeoutMs(
-		$env.PI_STREAM_IDLE_TIMEOUT_MS ?? $env.PI_OPENAI_STREAM_IDLE_TIMEOUT_MS,
-		DEFAULT_STREAM_IDLE_TIMEOUT_MS,
-	);
+export function getStreamIdleTimeoutMs(fallbackMs: number = DEFAULT_STREAM_IDLE_TIMEOUT_MS): number | undefined {
+	return normalizeIdleTimeoutMs($env.PI_STREAM_IDLE_TIMEOUT_MS ?? $env.PI_OPENAI_STREAM_IDLE_TIMEOUT_MS, fallbackMs);
 }
 
 /**
@@ -42,12 +43,17 @@ export function getOpenAIStreamIdleTimeoutMs(): number | undefined {
  * so the default never undershoots the steady-state idle timeout.
  *
  * Set `PI_STREAM_FIRST_EVENT_TIMEOUT_MS=0` to disable the watchdog.
+ *
+ * Providers whose first response can legitimately take longer (heavy reasoning,
+ * slow cold-start proxies) can pass `fallbackMs` to widen the floor used when
+ * neither env var nor caller option is set. Caller options still take precedence;
+ * env overrides still trump the fallback.
  */
-export function getStreamFirstEventTimeoutMs(idleTimeoutMs?: number): number | undefined {
-	const fallback =
-		idleTimeoutMs === undefined
-			? DEFAULT_STREAM_FIRST_EVENT_TIMEOUT_MS
-			: Math.max(DEFAULT_STREAM_FIRST_EVENT_TIMEOUT_MS, idleTimeoutMs);
+export function getStreamFirstEventTimeoutMs(
+	idleTimeoutMs?: number,
+	fallbackMs: number = DEFAULT_STREAM_FIRST_EVENT_TIMEOUT_MS,
+): number | undefined {
+	const fallback = idleTimeoutMs === undefined ? fallbackMs : Math.max(fallbackMs, idleTimeoutMs);
 	return normalizeIdleTimeoutMs($env.PI_STREAM_FIRST_EVENT_TIMEOUT_MS, fallback);
 }
 
diff --git a/packages/ai/test/stream-timeout-defaults.test.ts b/packages/ai/test/stream-timeout-defaults.test.ts
new file mode 100644
index 000000000..15efa15a4
--- /dev/null
+++ b/packages/ai/test/stream-timeout-defaults.test.ts
@@ -0,0 +1,81 @@
+import { afterEach, beforeEach, describe, expect, it } from "bun:test";
+import { getStreamFirstEventTimeoutMs, getStreamIdleTimeoutMs } from "../src/utils/idle-iterator";
+
+/**
+ * Per-provider fallback overrides on the stream-watchdog helpers.
+ *
+ * These are the gear that lets `google-gemini-cli` widen its first-event floor
+ * beyond the 100s global default without forcing every other provider to wait
+ * just as long. Tests pin the precedence contract callers depend on:
+ * caller option > env var > per-provider fallback > base default.
+ */
+
+const ENV_KEYS = [
+	"PI_STREAM_IDLE_TIMEOUT_MS",
+	"PI_OPENAI_STREAM_IDLE_TIMEOUT_MS",
+	"PI_STREAM_FIRST_EVENT_TIMEOUT_MS",
+] as const;
+
+const originalEnv: Partial<Record<(typeof ENV_KEYS)[number], string | undefined>> = {};
+
+beforeEach(() => {
+	for (const key of ENV_KEYS) {
+		originalEnv[key] = Bun.env[key];
+		delete Bun.env[key];
+	}
+});
+
+afterEach(() => {
+	for (const key of ENV_KEYS) {
+		const prior = originalEnv[key];
+		if (prior === undefined) {
+			delete Bun.env[key];
+		} else {
+			Bun.env[key] = prior;
+		}
+	}
+});
+
+describe("getStreamIdleTimeoutMs(fallbackMs)", () => {
+	it("returns the per-provider fallback when env vars are unset", () => {
+		expect(getStreamIdleTimeoutMs(300_000)).toBe(300_000);
+	});
+
+	it("lets PI_STREAM_IDLE_TIMEOUT_MS override the per-provider fallback", () => {
+		Bun.env.PI_STREAM_IDLE_TIMEOUT_MS = "42";
+		expect(getStreamIdleTimeoutMs(300_000)).toBe(42);
+	});
+
+	it("treats PI_STREAM_IDLE_TIMEOUT_MS=0 as a watchdog disable", () => {
+		Bun.env.PI_STREAM_IDLE_TIMEOUT_MS = "0";
+		expect(getStreamIdleTimeoutMs(300_000)).toBeUndefined();
+	});
+});
+
+describe("getStreamFirstEventTimeoutMs(idleTimeoutMs, fallbackMs)", () => {
+	it("returns the per-provider fallback when env unset and idle timeout is undefined", () => {
+		expect(getStreamFirstEventTimeoutMs(undefined, 300_000)).toBe(300_000);
+	});
+
+	it("floors the first-event timeout at the per-provider fallback even when idle is shorter", () => {
+		expect(getStreamFirstEventTimeoutMs(50_000, 300_000)).toBe(300_000);
+	});
+
+	it("never undershoots the steady-state idle timeout", () => {
+		expect(getStreamFirstEventTimeoutMs(500_000, 300_000)).toBe(500_000);
+	});
+
+	it("lets PI_STREAM_FIRST_EVENT_TIMEOUT_MS override the per-provider fallback", () => {
+		Bun.env.PI_STREAM_FIRST_EVENT_TIMEOUT_MS = "42";
+		expect(getStreamFirstEventTimeoutMs(undefined, 300_000)).toBe(42);
+	});
+
+	it("treats PI_STREAM_FIRST_EVENT_TIMEOUT_MS=0 as a watchdog disable", () => {
+		Bun.env.PI_STREAM_FIRST_EVENT_TIMEOUT_MS = "0";
+		expect(getStreamFirstEventTimeoutMs(undefined, 300_000)).toBeUndefined();
+	});
+
+	it("falls back to the 100s global default when no fallback or env is provided", () => {
+		expect(getStreamFirstEventTimeoutMs()).toBe(100_000);
+	});
+});