fix(ai): omit strict for unsupported openai completions

packages/ai/CHANGELOG.md

@@ -6,6 +6,7 @@
 
 - Fixed `cacheRetention` option not being passed through in `buildBaseOptions` ([#1154](https://github.com/badlogic/pi-mono/issues/1154))
 - Fixed OAuth login/refresh not using HTTP proxy settings (`HTTP_PROXY`, `HTTPS_PROXY` env vars) ([#1132](https://github.com/badlogic/pi-mono/issues/1132))
+- Fixed OpenAI-compatible completions to omit unsupported `strict` tool fields for providers that reject them ([#1172](https://github.com/badlogic/pi-mono/issues/1172))
 
 ## [0.50.9] - 2026-02-01
 

packages/ai/README.md

@@ -731,8 +731,16 @@ interface OpenAICompletionsCompat {
   supportsStore?: boolean;           // Whether provider supports the `store` field (default: true)
   supportsDeveloperRole?: boolean;   // Whether provider supports `developer` role vs `system` (default: true)
   supportsReasoningEffort?: boolean; // Whether provider supports `reasoning_effort` (default: true)
+  supportsUsageInStreaming?: boolean; // Whether provider supports `stream_options: { include_usage: true }` (default: true)
+  supportsStrictMode?: boolean;      // Whether provider supports `strict` in tool definitions (default: true)
   maxTokensField?: 'max_completion_tokens' | 'max_tokens';  // Which field name to use (default: max_completion_tokens)
+  requiresToolResultName?: boolean;  // Whether tool results require the `name` field (default: false)
+  requiresAssistantAfterToolResult?: boolean; // Whether tool results must be followed by an assistant message (default: false)
+  requiresThinkingAsText?: boolean;  // Whether thinking blocks must be converted to text (default: false)
+  requiresMistralToolIds?: boolean;  // Whether tool call IDs must be normalized to Mistral format (default: false)
   thinkingFormat?: 'openai' | 'zai' | 'qwen'; // Format for reasoning param: 'openai' uses reasoning_effort, 'zai' uses thinking: { type: "enabled" }, 'qwen' uses enable_thinking: boolean (default: openai)
+  openRouterRouting?: OpenRouterRouting; // OpenRouter routing preferences (default: {})
+  vercelGatewayRouting?: VercelGatewayRouting; // Vercel AI Gateway routing preferences (default: {})
 }
 
 interface OpenAIResponsesCompat {

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

@@ -428,7 +428,7 @@ function buildParams(model: Model<"openai-completions">, context: Context, optio
 	}
 
 	if (context.tools) {
-		params.tools = convertTools(context.tools);
+		params.tools = convertTools(context.tools, compat);
 	} else if (hasToolHistory(context.messages)) {
 		// Anthropic (via LiteLLM/proxy) requires tools param when conversation has tool_calls/tool_results
 		params.tools = [];
@@ -738,14 +738,18 @@ export function convertMessages(
 	return params;
 }
 
-function convertTools(tools: Tool[]): OpenAI.Chat.Completions.ChatCompletionTool[] {
+function convertTools(
+	tools: Tool[],
+	compat: Required<OpenAICompletionsCompat>,
+): OpenAI.Chat.Completions.ChatCompletionTool[] {
 	return tools.map((tool) => ({
 		type: "function",
 		function: {
 			name: tool.name,
 			description: tool.description,
 			parameters: tool.parameters as any, // TypeBox already generates JSON Schema
-			strict: false, // Disable strict mode to allow optional parameters without null unions
+			// Only include strict if provider supports it. Some reject unknown fields.
+			...(compat.supportsStrictMode !== false && { strict: false }),
 		},
 	}));
 }
@@ -812,6 +816,7 @@ function detectCompat(model: Model<"openai-completions">): Required<OpenAIComple
 		thinkingFormat: isZai ? "zai" : "openai",
 		openRouterRouting: {},
 		vercelGatewayRouting: {},
+		supportsStrictMode: true,
 	};
 }
 
@@ -837,5 +842,6 @@ function getCompat(model: Model<"openai-completions">): Required<OpenAICompletio
 		thinkingFormat: model.compat.thinkingFormat ?? detected.thinkingFormat,
 		openRouterRouting: model.compat.openRouterRouting ?? {},
 		vercelGatewayRouting: model.compat.vercelGatewayRouting ?? detected.vercelGatewayRouting,
+		supportsStrictMode: model.compat.supportsStrictMode ?? detected.supportsStrictMode,
 	};
 }

packages/ai/src/types.ts

@@ -235,6 +235,8 @@ export interface OpenAICompletionsCompat {
 	openRouterRouting?: OpenRouterRouting;
 	/** Vercel AI Gateway routing preferences. Only used when baseUrl points to Vercel AI Gateway. */
 	vercelGatewayRouting?: VercelGatewayRouting;
+	/** Whether the provider supports the `strict` field in tool definitions. Default: true. */
+	supportsStrictMode?: boolean;
 }
 
 /** Compatibility settings for OpenAI Responses APIs. */

packages/ai/test/openai-completions-tool-choice.test.ts

@@ -1,38 +1,40 @@
 import { Type } from "@sinclair/typebox";
 import { describe, expect, it, vi } from "vitest";
+import { getModel } from "../src/models.js";
+import { streamSimple } from "../src/stream.js";
 import type { Tool } from "../src/types.js";
 
-let lastParams: unknown;
+const mockState = vi.hoisted(() => ({ lastParams: undefined as unknown }));
 
-class FakeOpenAI {
-	chat = {
-		completions: {
-			create: async (params: unknown) => {
-				lastParams = params;
-				return {
-					async *[Symbol.asyncIterator]() {
-						yield {
-							choices: [{ delta: {}, finish_reason: "stop" }],
-							usage: {
-								prompt_tokens: 1,
-								completion_tokens: 1,
-								prompt_tokens_details: { cached_tokens: 0 },
-								completion_tokens_details: { reasoning_tokens: 0 },
-							},
-						};
-					},
-				};
+vi.mock("openai", () => {
+	class FakeOpenAI {
+		chat = {
+			completions: {
+				create: async (params: unknown) => {
+					mockState.lastParams = params;
+					return {
+						async *[Symbol.asyncIterator]() {
+							yield {
+								choices: [{ delta: {}, finish_reason: "stop" }],
+								usage: {
+									prompt_tokens: 1,
+									completion_tokens: 1,
+									prompt_tokens_details: { cached_tokens: 0 },
+									completion_tokens_details: { reasoning_tokens: 0 },
+								},
+							};
+						},
+					};
+				},
 			},
-		},
-	};
-}
+		};
+	}
 
-vi.mock("openai", () => ({ default: FakeOpenAI }));
+	return { default: FakeOpenAI };
+});
 
 describe("openai-completions tool_choice", () => {
 	it("forwards toolChoice from simple options to payload", async () => {
-		const { streamSimple } = await import("../src/stream.js");
-		const { getModel } = await import("../src/models.js");
 		const { compat: _compat, ...baseModel } = getModel("openai", "gpt-4o-mini")!;
 		const model = { ...baseModel, api: "openai-completions" } as const;
 		const tools: Tool[] = [
@@ -67,9 +69,54 @@ describe("openai-completions tool_choice", () => {
 			} as unknown as Parameters<typeof streamSimple>[2],
 		).result();
 
-		const params = (payload ?? lastParams) as { tool_choice?: string; tools?: unknown[] };
+		const params = (payload ?? mockState.lastParams) as { tool_choice?: string; tools?: unknown[] };
 		expect(params.tool_choice).toBe("required");
 		expect(Array.isArray(params.tools)).toBe(true);
 		expect(params.tools?.length ?? 0).toBeGreaterThan(0);
 	});
+
+	it("omits strict when compat disables strict mode", async () => {
+		const { compat: _compat, ...baseModel } = getModel("openai", "gpt-4o-mini")!;
+		const model = {
+			...baseModel,
+			api: "openai-completions",
+			compat: { supportsStrictMode: false },
+		} as const;
+		const tools: Tool[] = [
+			{
+				name: "ping",
+				description: "Ping tool",
+				parameters: Type.Object({
+					ok: Type.Boolean(),
+				}),
+			},
+		];
+		let payload: unknown;
+
+		await streamSimple(
+			model,
+			{
+				messages: [
+					{
+						role: "user",
+						content: "Call ping with ok=true",
+						timestamp: Date.now(),
+					},
+				],
+				tools,
+			},
+			{
+				apiKey: "test",
+				onPayload: (params: unknown) => {
+					payload = params;
+				},
+			} as unknown as Parameters<typeof streamSimple>[2],
+		).result();
+
+		const params = (payload ?? mockState.lastParams) as { tools?: Array<{ function?: Record<string, unknown> }> };
+		const tool = params.tools?.[0]?.function;
+		expect(tool).toBeTruthy();
+		expect(tool?.strict).toBeUndefined();
+		expect("strict" in (tool ?? {})).toBe(false);
+	});
 });

packages/ai/test/openai-completions-tool-result-images.test.ts

@@ -32,6 +32,7 @@ const compat: Required<OpenAICompletionsCompat> = {
 	thinkingFormat: "openai",
 	openRouterRouting: {},
 	vercelGatewayRouting: {},
+	supportsStrictMode: true,
 };
 
 function buildToolResult(toolCallId: string, timestamp: number): ToolResultMessage {