fix(ai): disabled local first-event watchdogs

- Added a per-model first-event watchdog policy and disabled it for local OpenAI-compatible backends while retaining inter-event stall detection.
- Applied the policy to Responses and chat-completions transports with regression coverage for resolver and runtime precedence.

Fixes #6524

packages/ai/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed OpenAI Responses and chat-completions streams honoring per-model first-event watchdog policy, allowing local llama.cpp-style backends to process arbitrarily large prompts without a premature client cancellation ([#6524](https://github.com/can1357/oh-my-pi/issues/6524)).
+
 ## [17.1.2] - 2026-07-24
 
 ### Added

packages/ai/src/providers/openai-completions.ts

@@ -630,7 +630,8 @@ const streamOpenAICompletionsOnce = (
 			const idleTimeoutFallbackMs = model.compat.streamIdleTimeoutMs;
 			const idleTimeoutMs = options?.streamIdleTimeoutMs ?? getOpenAIStreamIdleTimeoutMs(idleTimeoutFallbackMs);
 			const firstEventTimeoutMs =
-				options?.streamFirstEventTimeoutMs ?? getOpenAIStreamFirstEventTimeoutMs(idleTimeoutMs);
+				options?.streamFirstEventTimeoutMs ??
+				getOpenAIStreamFirstEventTimeoutMs(idleTimeoutMs, model.compat.streamFirstEventTimeoutMs);
 			const requestTimeoutMs =
 				firstEventTimeoutMs !== undefined && firstEventTimeoutMs > 0 ? firstEventTimeoutMs : undefined;
 			const { copilotPremiumRequests, baseUrl, headers, query, requestHeaders } = createRequestSetup(

packages/ai/src/providers/openai-responses.ts

@@ -495,7 +495,8 @@ const streamOpenAIResponsesOnce = (
 			const idleTimeoutMs =
 				options?.streamIdleTimeoutMs ?? getOpenAIStreamIdleTimeoutMs(model.compat.streamIdleTimeoutMs);
 			const firstEventTimeoutMs =
-				options?.streamFirstEventTimeoutMs ?? getOpenAIStreamFirstEventTimeoutMs(idleTimeoutMs);
+				options?.streamFirstEventTimeoutMs ??
+				getOpenAIStreamFirstEventTimeoutMs(idleTimeoutMs, model.compat.streamFirstEventTimeoutMs);
 			const requestTimeoutMs =
 				firstEventTimeoutMs !== undefined && firstEventTimeoutMs > 0 ? firstEventTimeoutMs : undefined;
 			const requestUrl = `${resolvedBaseUrl}/responses`;

packages/ai/src/utils/idle-iterator.ts

@@ -68,11 +68,13 @@ export function getStreamFirstEventTimeoutMs(
  * `"0"` disable) wins outright. Otherwise the resolved idle (caller-supplied
  * `idleTimeoutMs` — which itself already encompasses per-call
  * `streamIdleTimeoutMs` or `PI_OPENAI_STREAM_IDLE_TIMEOUT_MS` resolved
- * upstream) floors the first-event budget so slow local OpenAI-compatible
- * servers are not undercut by a shorter `PI_STREAM_FIRST_EVENT_TIMEOUT_MS`
- * or the global default during prompt processing.
+ * upstream) floors the first-event budget so slow OpenAI-compatible servers
+ * are not undercut by a shorter `PI_STREAM_FIRST_EVENT_TIMEOUT_MS` or the
+ * global default during prompt processing. A zero per-provider fallback
+ * disables the first-event watchdog unless an environment override is set.
  *
- * Returns `undefined` when an explicit env knob disables the watchdog.
+ * Returns `undefined` when an explicit env knob or per-provider fallback
+ * disables the watchdog.
  */
 export function getOpenAIStreamFirstEventTimeoutMs(
 	idleTimeoutMs?: number,
@@ -83,7 +85,7 @@ export function getOpenAIStreamFirstEventTimeoutMs(
 		return normalizeIdleTimeoutMs(openAIFirstEventRaw, fallbackMs);
 	}
 	const base = normalizeIdleTimeoutMs($env.PI_STREAM_FIRST_EVENT_TIMEOUT_MS, fallbackMs);
-	if (base === undefined) return undefined;
+	if (base === undefined || base <= 0) return undefined;
 	if (idleTimeoutMs === undefined || idleTimeoutMs <= 0) return base;
 	return Math.max(base, idleTimeoutMs);
 }

packages/ai/test/openai-completions-progress-chunk.test.ts

@@ -191,7 +191,7 @@ describe("resolveOpenAICompat stream idle timeout", () => {
 		expect(openAICompletionsModel.compat.streamIdleTimeoutMs).toBeUndefined();
 	});
 
-	it("widens local OpenAI-compatible stream watchdogs", () => {
+	it("widens local idle watchdogs and disables first-event deadlines", () => {
 		const completions = buildModel({
 			...openAICompletionsModel,
 			id: "qwen3-local",
@@ -210,7 +210,9 @@ describe("resolveOpenAICompat stream idle timeout", () => {
 		} as ModelSpec<"openai-responses">);
 
 		expect(completions.compat.streamIdleTimeoutMs).toBe(300_000);
+		expect(completions.compat.streamFirstEventTimeoutMs).toBe(0);
 		expect(responses.compat.streamIdleTimeoutMs).toBe(300_000);
+		expect(responses.compat.streamFirstEventTimeoutMs).toBe(0);
 	});
 
 	it("widens custom loopback OpenAI-compatible responses stream watchdogs", () => {
@@ -224,6 +226,7 @@ describe("resolveOpenAICompat stream idle timeout", () => {
 		} as ModelSpec<"openai-responses">);
 
 		expect(model.compat.streamIdleTimeoutMs).toBe(300_000);
+		expect(model.compat.streamFirstEventTimeoutMs).toBe(0);
 	});
 
 	it("widens Xiaomi MiMo Pro stream watchdog (issue #1770)", () => {

packages/ai/test/openai-first-event-timeout.test.ts

@@ -861,4 +861,29 @@ describe("OpenAI-family first-event timeouts", () => {
 		expect(result.stopReason).toBe("error");
 		expect(result.errorMessage).toBe("OpenAI responses stream stalled while waiting for the next event");
 	});
+
+	it("honors streamFirstEventTimeoutMs from model.compat for OpenAI responses streams", async () => {
+		const customResponsesModel: Model<"openai-responses"> = buildModel({
+			id: "slow-first-event",
+			name: "Slow First Event",
+			api: "openai-responses",
+			provider: "custom",
+			baseUrl: "https://example.com/v1",
+			reasoning: false,
+			input: ["text"],
+			cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+			contextWindow: 128000,
+			maxTokens: 16384,
+			compat: { streamFirstEventTimeoutMs: 20, streamIdleTimeoutMs: 5 },
+		});
+		const fetchMock = createDelayedFetch(30, createOpenAIResponsesSuccessResponse);
+
+		const result = await streamOpenAIResponses(customResponsesModel, baseContext(), {
+			apiKey: "test-key",
+			fetch: fetchMock,
+		}).result();
+
+		expect(result.stopReason).toBe("error");
+		expect(result.errorMessage).toBe("OpenAI responses stream timed out while waiting for the first event");
+	});
 });

packages/ai/test/stream-timeout-defaults.test.ts

@@ -123,6 +123,10 @@ describe("getOpenAIStreamFirstEventTimeoutMs(idleTimeoutMs, fallbackMs)", () =>
 		expect(getOpenAIStreamFirstEventTimeoutMs(1500, 100_000)).toBeUndefined();
 	});
 
+	it("treats a zero per-provider fallback as a watchdog disable", () => {
+		expect(getOpenAIStreamFirstEventTimeoutMs(300_000, 0)).toBeUndefined();
+	});
+
 	it("falls back to the generic first-event env when OpenAI env vars are unset", () => {
 		Bun.env.PI_STREAM_FIRST_EVENT_TIMEOUT_MS = "42";
 		expect(getOpenAIStreamFirstEventTimeoutMs(undefined, 300_000)).toBe(42);

packages/catalog/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Disabled the first-event watchdog for local OpenAI-compatible backends while retaining the 300-second inter-event watchdog, so long llama.cpp prompt prefill is not canceled and retried ([#6524](https://github.com/can1357/oh-my-pi/issues/6524)).
+
 ## [17.1.1] - 2026-07-24
 
 ### Added

packages/catalog/src/compat/openai.ts

@@ -574,6 +574,7 @@ export function buildOpenAICompat(spec: ModelSpec<"openai-completions">): Resolv
 		// to Moonshot verbatim, which 400s on non-MFJS constructs.
 		toolSchemaFlavor:
 			isMoonshotNative || isKimiModel ? "moonshot-mfjs" : isLocalOpenAICompatBackend ? "grammar" : undefined,
+		streamFirstEventTimeoutMs: isLocalServingBackend ? 0 : undefined,
 		streamIdleTimeoutMs,
 		stripDeepseekSpecialTokens:
 			isDeepseekModelIdOrName(spec.id) && (provider === "nvidia" || provider === "deepseek"),
@@ -723,6 +724,7 @@ export function buildOpenAIResponsesCompat(spec: OpenAIResponsesSpecLike): Resol
 		emptyLengthFinishIsContextError: spec.provider === "ollama",
 		usesOpenAIToolCallIdLimit: spec.provider === "openai",
 		promptCacheSessionHeader: spec.provider === "xai-oauth" ? "x-grok-conv-id" : undefined,
+		streamFirstEventTimeoutMs: isLocalServingBackend ? 0 : spec.compat?.streamFirstEventTimeoutMs,
 		streamIdleTimeoutMs: isLocalServingBackend
 			? LOCAL_OPENAI_COMPAT_STREAM_IDLE_TIMEOUT_MS
 			: spec.compat?.streamIdleTimeoutMs,

packages/catalog/src/types.ts

@@ -341,6 +341,12 @@ export interface OpenAICompat {
 	 * to opt a host out.
 	 */
 	toolSchemaFlavor?: "moonshot-mfjs" | "grammar" | "none";
+	/**
+	 * Stream-watchdog first-event timeout in ms.
+	 * Set to `0` to allow unbounded prompt processing. Default: auto-detected
+	 * (disabled for local OpenAI-compatible backends).
+	 */
+	streamFirstEventTimeoutMs?: number;
 	/**
 	 * Stream-watchdog idle-timeout floor in ms for slow reasoning hosts.
 	 * Default: auto-detected (GLM coding-plan hosts, direct DeepSeek reasoning).
@@ -565,6 +571,8 @@ export interface ResolvedOpenAISharedCompat {
 	requiresAssistantContentForToolCalls: boolean;
 	stripDeepseekSpecialTokens: boolean;
 	streamMarkupHealingPattern?: OpenAIStreamMarkupHealingPattern;
+	/** See {@link OpenAICompat.streamFirstEventTimeoutMs}. */
+	streamFirstEventTimeoutMs?: number;
 	reasoningDeltasMayBeCumulative: boolean;
 	emptyLengthFinishIsContextError: boolean;
 	usesOpenAIToolCallIdLimit: boolean;
@@ -645,6 +653,7 @@ export type ResolvedOpenAICompat = ResolvedOpenAISharedCompat &
 			| "extraBody"
 			| "toolStrictMode"
 			| "toolSchemaFlavor"
+			| "streamFirstEventTimeoutMs"
 			| "streamIdleTimeoutMs"
 			| "cacheControlFormat"
 			| "thinkingKeep"