fix(catalog): used Moonshot MFJS schema for Kimi models on all hosts

- Enable `moonshot-mfjs` tool schema flavor for Kimi-family ids on any host, not just native endpoints, since proxies forward schemas verbatim to Moonshot's validator.

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

@@ -38,6 +38,7 @@ import {
 	adaptSchemaForStrict,
 	findStrictToolSchemaViolation,
 	NO_STRICT,
+	normalizeSchemaForMoonshot,
 	sanitizeSchemaForOpenAIResponses,
 	toolWireSchema,
 } from "../utils/schema";
@@ -999,7 +1000,15 @@ export function convertTools(
 		}
 		const strict = !NO_STRICT && strictMode && tool.strict !== false;
 		const baseParameters = toolWireSchema(tool);
-		const responseParameters = sanitizeSchemaForOpenAIResponses(baseParameters);
+		// MFJS must run AFTER the Responses sanitizer: the sanitizer normalizes
+		// `{}` → `true` (issue #1179), and Moonshot's validator rejects boolean
+		// subschemas ("property schema … must be an object"), so the Moonshot
+		// pass re-coerces them last.
+		const sanitized = sanitizeSchemaForOpenAIResponses(baseParameters);
+		const responseParameters =
+			model.compat.toolSchemaFlavor === "moonshot-mfjs"
+				? (normalizeSchemaForMoonshot(sanitized) as Record<string, unknown>)
+				: sanitized;
 		const { schema: parameters, strict: effectiveStrict } = adaptSchemaForStrict(responseParameters, strict);
 		// Quarantine a tool whose emitted schema carries a provider-rejecting
 		// enum/const-vs-type contradiction: dropping just that tool keeps the rest

packages/catalog/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Changed
+
+- Kimi-family models now use MFJS tool schema on all hosts, including proxies like OpenRouter that forward schemas to Moonshot
+
 ## [17.0.3] - 2026-07-17
 
 ### Fixed

packages/catalog/src/compat/openai.ts

@@ -532,7 +532,10 @@ export function buildOpenAICompat(spec: ModelSpec<"openai-completions">): Resolv
 		supportsStrictMode: detectStrictModeSupport(provider, baseUrl),
 		extraBody: isDirectDeepseekReasoning ? { thinking: { type: "enabled" } } : undefined,
 		toolStrictMode: isCerebras ? "all_strict" : "mixed",
-		toolSchemaFlavor: isMoonshotNative ? "moonshot-mfjs" : undefined,
+		// Kimi-family ids trigger MFJS on any host, not just native base URLs:
+		// proxies (OpenRouter, custom gateways) forward `tools.function.parameters`
+		// to Moonshot verbatim, which 400s on non-MFJS constructs.
+		toolSchemaFlavor: isMoonshotNative || isKimiModel ? "moonshot-mfjs" : undefined,
 		streamIdleTimeoutMs,
 		stripDeepseekSpecialTokens:
 			isDeepseekModelIdOrName(spec.id) && (provider === "nvidia" || provider === "deepseek"),
@@ -658,6 +661,9 @@ export function buildOpenAIResponsesCompat(spec: OpenAIResponsesSpecLike): Resol
 		openRouterRouting: undefined,
 		isOpenRouterHost: isOpenRouter,
 		wireModelIdMode: isOpenRouter ? "openrouter" : "raw",
+		// Mirrors buildOpenAICompat: Kimi behind a Responses-capable proxy still
+		// lands on Moonshot's MFJS validator.
+		toolSchemaFlavor: isKimiModel ? "moonshot-mfjs" : undefined,
 		alwaysSendMaxTokens: spec.id ? isKimiModelId(spec.id) : false,
 		enableGeminiThinkingLoopGuard: modelFamilyToken(spec.id ?? "") === "gemini",
 		supportsObfuscationOptOut: isOpenAIUrl || spec.provider === "openai",

packages/catalog/src/types.ts

@@ -314,8 +314,10 @@ export interface OpenAICompat {
 	 * normalization (collapse `const`→`enum`, infer `type` on bare enums, strip
 	 * unsupported validators/`prefixItems`) because Moonshot/Kimi native hosts
 	 * reject standard JSON Schema constructs with HTTP 400. Default:
-	 * auto-detected (`"moonshot-mfjs"` on api.moonshot.ai / api.kimi.com). Set
-	 * `"none"` to opt a custom Moonshot-compatible host out.
+	 * auto-detected — Moonshot native hosts (api.moonshot.ai / api.kimi.com)
+	 * and Kimi-family model ids on any host, since proxies (OpenRouter, custom
+	 * gateways) forward schemas to Moonshot verbatim. Set `"none"` to opt a
+	 * host out.
 	 */
 	toolSchemaFlavor?: "moonshot-mfjs" | "none";
 	/**
@@ -514,6 +516,8 @@ export interface ResolvedOpenAISharedCompat {
 	openRouterRouting?: OpenAICompat["openRouterRouting"];
 	/** Provider-specific wire model-id transform applied to the base id. */
 	wireModelIdMode: "raw" | "firepass" | "fireworks" | "openrouter";
+	/** See {@link OpenAICompat.toolSchemaFlavor}. Read by both wire paths when converting tools. */
+	toolSchemaFlavor?: OpenAICompat["toolSchemaFlavor"];
 }
 
 /**
@@ -584,7 +588,6 @@ export type ResolvedOpenAICompat = ResolvedOpenAISharedCompat &
 		thinkingKeep?: OpenAICompat["thinkingKeep"];
 		streamIdleTimeoutMs?: number;
 		toolStrictMode: ResolvedToolStrictMode;
-		toolSchemaFlavor?: OpenAICompat["toolSchemaFlavor"];
 		/** The model sits behind Vercel AI Gateway. */
 		isVercelGatewayHost: boolean;
 		dropThinkingWhenReasoningEffort: boolean;