diff --git a/packages/pi-ai/src/providers/azure-openai-responses.ts b/packages/pi-ai/src/providers/azure-openai-responses.ts
index 9a08b57f2..42646f533 100644
--- a/packages/pi-ai/src/providers/azure-openai-responses.ts
+++ b/packages/pi-ai/src/providers/azure-openai-responses.ts
@@ -5,8 +5,6 @@ import type { ResponseCreateParamsStreaming } from "openai/resources/responses/r
 import { getEnvApiKey } from "../env-api-keys.js";
 import { supportsXhigh } from "../models.js";
 import type {
-	Api,
-	AssistantMessage,
 	Context,
 	Model,
 	SimpleStreamOptions,
@@ -15,6 +13,13 @@ import type {
 } from "../types.js";
 import { AssistantMessageEventStream } from "../utils/event-stream.js";
 import { convertResponsesMessages, convertResponsesTools, processResponsesStream } from "./openai-responses-shared.js";
+import {
+	assertStreamSuccess,
+	buildInitialOutput,
+	clampReasoningForModel,
+	finalizeStream,
+	handleStreamError,
+} from "./openai-shared.js";
 import { buildBaseOptions, clampReasoning } from "./simple-options.js";
 
 let _AzureOpenAIClass: typeof AzureOpenAI | undefined;
@@ -26,16 +31,6 @@ async function getAzureOpenAIClass(): Promise<typeof AzureOpenAI> {
 	return _AzureOpenAIClass;
 }
 
-/**
- * Clamp reasoning effort for models that don't support all levels.
- * gpt-5.x models don't support "minimal" — map to "low".
- */
-function clampReasoningForModel(modelName: string, effort: string): string {
-	const name = modelName.includes("/") ? modelName.split("/").pop()! : modelName;
-	if (name.startsWith("gpt-5") && effort === "minimal") return "low";
-	return effort;
-}
-
 const DEFAULT_AZURE_API_VERSION = "v1";
 const AZURE_TOOL_CALL_PROVIDERS = new Set(["openai", "openai-codex", "opencode", "azure-openai-responses"]);
 
@@ -83,24 +78,7 @@ export const streamAzureOpenAIResponses: StreamFunction<"azure-openai-responses"
 	// Start async processing
 	(async () => {
 		const deploymentName = resolveDeploymentName(model, options);
-
-		const output: AssistantMessage = {
-			role: "assistant",
-			content: [],
-			api: "azure-openai-responses" as Api,
-			provider: model.provider,
-			model: model.id,
-			usage: {
-				input: 0,
-				output: 0,
-				cacheRead: 0,
-				cacheWrite: 0,
-				totalTokens: 0,
-				cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
-			},
-			stopReason: "stop",
-			timestamp: Date.now(),
-		};
+		const output = buildInitialOutput(model);
 
 		try {
 			// Create Azure OpenAI client
@@ -119,22 +97,10 @@ export const streamAzureOpenAIResponses: StreamFunction<"azure-openai-responses"
 
 			await processResponsesStream(openaiStream, output, stream, model);
 
-			if (options?.signal?.aborted) {
-				throw new Error("Request was aborted");
-			}
-
-			if (output.stopReason === "aborted" || output.stopReason === "error") {
-				throw new Error("An unknown error occurred");
-			}
-
-			stream.push({ type: "done", reason: output.stopReason, message: output });
-			stream.end();
+			assertStreamSuccess(output, options?.signal);
+			finalizeStream(stream, output);
 		} catch (error) {
-			for (const block of output.content) delete (block as { index?: number }).index;
-			output.stopReason = options?.signal?.aborted ? "aborted" : "error";
-			output.errorMessage = error instanceof Error ? error.message : JSON.stringify(error);
-			stream.push({ type: "error", reason: output.stopReason, error: output });
-			stream.end();
+			handleStreamError(stream, output, error, options?.signal);
 		}
 	})();
 
diff --git a/packages/pi-ai/src/providers/openai-completions.ts b/packages/pi-ai/src/providers/openai-completions.ts
index 7372d6880..4d6e1a3cf 100644
--- a/packages/pi-ai/src/providers/openai-completions.ts
+++ b/packages/pi-ai/src/providers/openai-completions.ts
@@ -31,19 +31,16 @@ import type {
 import { AssistantMessageEventStream } from "../utils/event-stream.js";
 import { parseStreamingJson } from "../utils/json-parse.js";
 import { sanitizeSurrogates } from "../utils/sanitize-unicode.js";
-import { buildCopilotDynamicHeaders, hasCopilotVisionInput } from "./github-copilot-headers.js";
 import { buildBaseOptions, clampReasoning } from "./simple-options.js";
+import {
+	assertStreamSuccess,
+	buildInitialOutput,
+	createOpenAIClient,
+	finalizeStream,
+	handleStreamError,
+} from "./openai-shared.js";
 import { transformMessages } from "./transform-messages.js";
 
-let _OpenAICompletionsClass: typeof OpenAI | undefined;
-async function getOpenAICompletionsClass(): Promise<typeof OpenAI> {
-	if (!_OpenAICompletionsClass) {
-		const mod = await import("openai");
-		_OpenAICompletionsClass = mod.default;
-	}
-	return _OpenAICompletionsClass;
-}
-
 /**
  * Check if conversation messages contain tool calls or tool results.
  * This is needed because Anthropic (via proxy) requires the tools param
@@ -76,27 +73,15 @@ export const streamOpenAICompletions: StreamFunction<"openai-completions", OpenA
 	const stream = new AssistantMessageEventStream();
 
 	(async () => {
-		const output: AssistantMessage = {
-			role: "assistant",
-			content: [],
-			api: model.api,
-			provider: model.provider,
-			model: model.id,
-			usage: {
-				input: 0,
-				output: 0,
-				cacheRead: 0,
-				cacheWrite: 0,
-				totalTokens: 0,
-				cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
-			},
-			stopReason: "stop",
-			timestamp: Date.now(),
-		};
+		const output = buildInitialOutput(model);
 
 		try {
 			const apiKey = options?.apiKey || getEnvApiKey(model.provider) || "";
-			const client = await createClient(model, context, apiKey, options?.headers);
+			const isZai = model.provider === "zai" || model.baseUrl.includes("api.z.ai");
+			const client = await createOpenAIClient(model, context, apiKey, {
+				optionsHeaders: options?.headers,
+				extraClientOptions: isZai ? { timeout: 100_000, maxRetries: 4 } : undefined,
+			});
 			let params = buildParams(model, context, options);
 			const nextParams = await options?.onPayload?.(params, model);
 			if (nextParams !== undefined) {
@@ -292,25 +277,12 @@ export const streamOpenAICompletions: StreamFunction<"openai-completions", OpenA
 			}
 
 			finishCurrentBlock(currentBlock);
-			if (options?.signal?.aborted) {
-				throw new Error("Request was aborted");
-			}
-
-			if (output.stopReason === "aborted" || output.stopReason === "error") {
-				throw new Error("An unknown error occurred");
-			}
-
-			stream.push({ type: "done", reason: output.stopReason, message: output });
-			stream.end();
+			assertStreamSuccess(output, options?.signal);
+			finalizeStream(stream, output);
 		} catch (error) {
-			for (const block of output.content) delete (block as any).index;
-			output.stopReason = options?.signal?.aborted ? "aborted" : "error";
-			output.errorMessage = error instanceof Error ? error.message : JSON.stringify(error);
 			// Some providers via OpenRouter give additional information in this field.
 			const rawMetadata = (error as any)?.error?.metadata?.raw;
-			if (rawMetadata) output.errorMessage += `\n${rawMetadata}`;
-			stream.push({ type: "error", reason: output.stopReason, error: output });
-			stream.end();
+			handleStreamError(stream, output, error, options?.signal, rawMetadata);
 		}
 	})();
 
@@ -338,48 +310,6 @@ export const streamSimpleOpenAICompletions: StreamFunction<"openai-completions",
 	} satisfies OpenAICompletionsOptions);
 };
 
-async function createClient(
-	model: Model<"openai-completions">,
-	context: Context,
-	apiKey?: string,
-	optionsHeaders?: Record<string, string>,
-) {
-	if (!apiKey) {
-		if (!process.env.OPENAI_API_KEY) {
-			throw new Error(
-				"OpenAI API key is required. Set OPENAI_API_KEY environment variable or pass it as an argument.",
-			);
-		}
-		apiKey = process.env.OPENAI_API_KEY;
-	}
-
-	const headers = { ...model.headers };
-	if (model.provider === "github-copilot") {
-		const hasImages = hasCopilotVisionInput(context.messages);
-		const copilotHeaders = buildCopilotDynamicHeaders({
-			messages: context.messages,
-			hasImages,
-		});
-		Object.assign(headers, copilotHeaders);
-	}
-
-	// Merge options headers last so they can override defaults
-	if (optionsHeaders) {
-		Object.assign(headers, optionsHeaders);
-	}
-
-	const isZai = model.provider === "zai" || model.baseUrl.includes("api.z.ai");
-	const OpenAIClass = await getOpenAICompletionsClass();
-
-	return new OpenAIClass({
-		apiKey,
-		baseURL: model.baseUrl,
-		dangerouslyAllowBrowser: true,
-		defaultHeaders: headers,
-		...(isZai && { timeout: 100_000, maxRetries: 4 }),
-	});
-}
-
 function buildParams(model: Model<"openai-completions">, context: Context, options?: OpenAICompletionsOptions) {
 	const compat = getCompat(model);
 	const messages = convertMessages(model, context, compat);
diff --git a/packages/pi-ai/src/providers/openai-responses.ts b/packages/pi-ai/src/providers/openai-responses.ts
index bf8fa347a..d7abd3c61 100644
--- a/packages/pi-ai/src/providers/openai-responses.ts
+++ b/packages/pi-ai/src/providers/openai-responses.ts
@@ -1,12 +1,9 @@
 // Lazy-loaded: OpenAI SDK is imported on first use, not at startup.
 // This avoids penalizing users who don't use OpenAI models.
-import type OpenAI from "openai";
 import type { ResponseCreateParamsStreaming } from "openai/resources/responses/responses.js";
 import { getEnvApiKey } from "../env-api-keys.js";
 import { supportsXhigh } from "../models.js";
 import type {
-	Api,
-	AssistantMessage,
 	CacheRetention,
 	Context,
 	Model,
@@ -16,29 +13,17 @@ import type {
 	Usage,
 } from "../types.js";
 import { AssistantMessageEventStream } from "../utils/event-stream.js";
-import { buildCopilotDynamicHeaders, hasCopilotVisionInput } from "./github-copilot-headers.js";
 import { convertResponsesMessages, convertResponsesTools, processResponsesStream } from "./openai-responses-shared.js";
+import {
+	assertStreamSuccess,
+	buildInitialOutput,
+	clampReasoningForModel,
+	createOpenAIClient,
+	finalizeStream,
+	handleStreamError,
+} from "./openai-shared.js";
 import { buildBaseOptions, clampReasoning } from "./simple-options.js";
 
-let _OpenAIResponsesClass: typeof OpenAI | undefined;
-async function getOpenAIResponsesClass(): Promise<typeof OpenAI> {
-	if (!_OpenAIResponsesClass) {
-		const mod = await import("openai");
-		_OpenAIResponsesClass = mod.default;
-	}
-	return _OpenAIResponsesClass;
-}
-
-/**
- * Clamp reasoning effort for models that don't support all levels.
- * gpt-5.x models don't support "minimal" — map to "low".
- */
-function clampReasoningForModel(modelName: string, effort: string): string {
-	const name = modelName.includes("/") ? modelName.split("/").pop()! : modelName;
-	if (name.startsWith("gpt-5") && effort === "minimal") return "low";
-	return effort;
-}
-
 const OPENAI_TOOL_CALL_PROVIDERS = new Set(["openai", "openai-codex", "opencode"]);
 
 /**
@@ -88,28 +73,14 @@ export const streamOpenAIResponses: StreamFunction<"openai-responses", OpenAIRes
 
 	// Start async processing
 	(async () => {
-		const output: AssistantMessage = {
-			role: "assistant",
-			content: [],
-			api: model.api as Api,
-			provider: model.provider,
-			model: model.id,
-			usage: {
-				input: 0,
-				output: 0,
-				cacheRead: 0,
-				cacheWrite: 0,
-				totalTokens: 0,
-				cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
-			},
-			stopReason: "stop",
-			timestamp: Date.now(),
-		};
+		const output = buildInitialOutput(model);
 
 		try {
 			// Create OpenAI client
 			const apiKey = options?.apiKey || getEnvApiKey(model.provider) || "";
-			const client = await createClient(model, context, apiKey, options?.headers);
+			const client = await createOpenAIClient(model, context, apiKey, {
+				optionsHeaders: options?.headers,
+			});
 			let params = buildParams(model, context, options);
 			const nextParams = await options?.onPayload?.(params, model);
 			if (nextParams !== undefined) {
@@ -126,22 +97,10 @@ export const streamOpenAIResponses: StreamFunction<"openai-responses", OpenAIRes
 				applyServiceTierPricing,
 			});
 
-			if (options?.signal?.aborted) {
-				throw new Error("Request was aborted");
-			}
-
-			if (output.stopReason === "aborted" || output.stopReason === "error") {
-				throw new Error("An unknown error occurred");
-			}
-
-			stream.push({ type: "done", reason: output.stopReason, message: output });
-			stream.end();
+			assertStreamSuccess(output, options?.signal);
+			finalizeStream(stream, output);
 		} catch (error) {
-			for (const block of output.content) delete (block as { index?: number }).index;
-			output.stopReason = options?.signal?.aborted ? "aborted" : "error";
-			output.errorMessage = error instanceof Error ? error.message : JSON.stringify(error);
-			stream.push({ type: "error", reason: output.stopReason, error: output });
-			stream.end();
+			handleStreamError(stream, output, error, options?.signal);
 		}
 	})();
 
@@ -167,45 +126,6 @@ export const streamSimpleOpenAIResponses: StreamFunction<"openai-responses", Sim
 	} satisfies OpenAIResponsesOptions);
 };
 
-async function createClient(
-	model: Model<"openai-responses">,
-	context: Context,
-	apiKey?: string,
-	optionsHeaders?: Record<string, string>,
-) {
-	if (!apiKey) {
-		if (!process.env.OPENAI_API_KEY) {
-			throw new Error(
-				"OpenAI API key is required. Set OPENAI_API_KEY environment variable or pass it as an argument.",
-			);
-		}
-		apiKey = process.env.OPENAI_API_KEY;
-	}
-
-	const headers = { ...model.headers };
-	if (model.provider === "github-copilot") {
-		const hasImages = hasCopilotVisionInput(context.messages);
-		const copilotHeaders = buildCopilotDynamicHeaders({
-			messages: context.messages,
-			hasImages,
-		});
-		Object.assign(headers, copilotHeaders);
-	}
-
-	// Merge options headers last so they can override defaults
-	if (optionsHeaders) {
-		Object.assign(headers, optionsHeaders);
-	}
-
-	const OpenAIClass = await getOpenAIResponsesClass();
-	return new OpenAIClass({
-		apiKey,
-		baseURL: model.baseUrl,
-		dangerouslyAllowBrowser: true,
-		defaultHeaders: headers,
-	});
-}
-
 function buildParams(model: Model<"openai-responses">, context: Context, options?: OpenAIResponsesOptions) {
 	const messages = convertResponsesMessages(model, context, OPENAI_TOOL_CALL_PROVIDERS);
 
diff --git a/packages/pi-ai/src/providers/openai-shared.ts b/packages/pi-ai/src/providers/openai-shared.ts
new file mode 100644
index 000000000..d3bdfc5cd
--- /dev/null
+++ b/packages/pi-ai/src/providers/openai-shared.ts
@@ -0,0 +1,193 @@
+/**
+ * Shared utilities for OpenAI Completions and Responses providers.
+ *
+ * This module consolidates code that is identical (or near-identical) across
+ * openai-completions.ts and openai-responses.ts to reduce duplication while
+ * preserving the subtle behavioural differences of each provider.
+ */
+
+import type OpenAI from "openai";
+import type {
+	Api,
+	AssistantMessage,
+	Context,
+	Model,
+	StopReason,
+} from "../types.js";
+import type { AssistantMessageEventStream } from "../utils/event-stream.js";
+import { buildCopilotDynamicHeaders, hasCopilotVisionInput } from "./github-copilot-headers.js";
+
+// =============================================================================
+// Lazy SDK loading
+// =============================================================================
+
+let _openAIClass: typeof OpenAI | undefined;
+
+/**
+ * Lazy-load the OpenAI SDK default export.
+ * Shared between Completions and Responses providers so the module is only
+ * imported once regardless of which provider is used first.
+ */
+export async function getOpenAIClass(): Promise<typeof OpenAI> {
+	if (!_openAIClass) {
+		const mod = await import("openai");
+		_openAIClass = mod.default;
+	}
+	return _openAIClass;
+}
+
+// =============================================================================
+// Client creation
+// =============================================================================
+
+export interface CreateClientOptions {
+	/** Extra headers from the options bag (merged last, can override defaults). */
+	optionsHeaders?: Record<string, string>;
+	/** Provider-specific client constructor options (e.g. timeout, maxRetries for Z.ai). */
+	extraClientOptions?: Record<string, unknown>;
+}
+
+/**
+ * Create an OpenAI SDK client instance.
+ *
+ * Handles:
+ * - API key resolution (explicit > env)
+ * - GitHub Copilot dynamic headers
+ * - Options header merging
+ * - Lazy SDK loading
+ */
+export async function createOpenAIClient<TApi extends Api>(
+	model: Model<TApi>,
+	context: Context,
+	apiKey: string | undefined,
+	options?: CreateClientOptions,
+): Promise<OpenAI> {
+	if (!apiKey) {
+		if (!process.env.OPENAI_API_KEY) {
+			throw new Error(
+				"OpenAI API key is required. Set OPENAI_API_KEY environment variable or pass it as an argument.",
+			);
+		}
+		apiKey = process.env.OPENAI_API_KEY;
+	}
+
+	const headers = { ...model.headers };
+	if (model.provider === "github-copilot") {
+		const hasImages = hasCopilotVisionInput(context.messages);
+		const copilotHeaders = buildCopilotDynamicHeaders({
+			messages: context.messages,
+			hasImages,
+		});
+		Object.assign(headers, copilotHeaders);
+	}
+
+	// Merge options headers last so they can override defaults
+	if (options?.optionsHeaders) {
+		Object.assign(headers, options.optionsHeaders);
+	}
+
+	const OpenAIClass = await getOpenAIClass();
+	return new OpenAIClass({
+		apiKey,
+		baseURL: model.baseUrl,
+		dangerouslyAllowBrowser: true,
+		defaultHeaders: headers,
+		...options?.extraClientOptions,
+	});
+}
+
+// =============================================================================
+// Initial output construction
+// =============================================================================
+
+/**
+ * Build the initial AssistantMessage output object used by all OpenAI stream
+ * handlers.  Every field is initialised to its zero/default value.
+ */
+export function buildInitialOutput<TApi extends Api>(model: Model<TApi>): AssistantMessage {
+	return {
+		role: "assistant",
+		content: [],
+		api: model.api as Api,
+		provider: model.provider,
+		model: model.id,
+		usage: {
+			input: 0,
+			output: 0,
+			cacheRead: 0,
+			cacheWrite: 0,
+			totalTokens: 0,
+			cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+		},
+		stopReason: "stop",
+		timestamp: Date.now(),
+	};
+}
+
+// =============================================================================
+// Stream lifecycle helpers
+// =============================================================================
+
+/**
+ * Shared post-stream checks.  Call after the provider-specific stream loop
+ * finishes successfully (before pushing the "done" event).
+ *
+ * Throws if the request was aborted or the output indicates an error.
+ */
+export function assertStreamSuccess(output: AssistantMessage, signal?: AbortSignal): void {
+	if (signal?.aborted) {
+		throw new Error("Request was aborted");
+	}
+	if (output.stopReason === "aborted" || output.stopReason === "error") {
+		throw new Error("An unknown error occurred");
+	}
+}
+
+/**
+ * Emit the "done" event and close the stream.
+ */
+export function finalizeStream(
+	stream: AssistantMessageEventStream,
+	output: AssistantMessage,
+): void {
+	stream.push({ type: "done", reason: output.stopReason as Extract<StopReason, "stop" | "length" | "toolUse">, message: output });
+	stream.end();
+}
+
+/**
+ * Handle an error during streaming.
+ *
+ * Cleans up any leftover `index` properties on content blocks, sets the
+ * appropriate stop reason and error message, then emits the "error" event.
+ */
+export function handleStreamError(
+	stream: AssistantMessageEventStream,
+	output: AssistantMessage,
+	error: unknown,
+	signal?: AbortSignal,
+	/** Extra error metadata to append (e.g. OpenRouter raw metadata). */
+	extraMessage?: string,
+): void {
+	for (const block of output.content) delete (block as { index?: number }).index;
+	output.stopReason = signal?.aborted ? "aborted" : "error";
+	output.errorMessage = error instanceof Error ? error.message : JSON.stringify(error);
+	if (extraMessage) output.errorMessage += `\n${extraMessage}`;
+	stream.push({ type: "error", reason: output.stopReason, error: output });
+	stream.end();
+}
+
+// =============================================================================
+// Reasoning helpers
+// =============================================================================
+
+/**
+ * Clamp reasoning effort for models that don't support all levels.
+ * gpt-5.x models don't support "minimal" -- map to "low".
+ *
+ * Used by both openai-responses.ts and azure-openai-responses.ts.
+ */
+export function clampReasoningForModel(modelName: string, effort: string): string {
+	const name = modelName.includes("/") ? modelName.split("/").pop()! : modelName;
+	if (name.startsWith("gpt-5") && effort === "minimal") return "low";
+	return effort;
+}