feat(api-compat): response sanitization, role normalization, structured output for Gemini

- Add responseSanitizer.ts: strips non-standard fields (x_groq, usage_breakdown, service_tier),
  extracts <think> tags into reasoning_content, normalizes id/object/usage for strict OpenAI SDK v1.83+ compatibility
- Add roleNormalizer.ts: developer→system for non-OpenAI providers, system→user merging for GLM/ERNIE models
- Integrate sanitizer into chatCore.ts (non-streaming) and stream.ts (streaming passthrough)
- Integrate role normalizer into translator/index.ts pipeline
- Add response_format (json_schema/json_object) → Gemini responseMimeType/responseSchema conversion
- Update CHANGELOG.md with v1.1.0 entry
- Update README.md, ARCHITECTURE.md, TROUBLESHOOTING.md with new capabilities

CHANGELOG.md

@@ -7,6 +7,55 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ---
 
+## [1.1.0] — 2026-02-18
+
+> ### 🔧 API Compatibility & SDK Hardening
+>
+> Response sanitization, role normalization, and structured output improvements for strict OpenAI SDK compatibility and cross-provider robustness.
+
+### 🛡️ Response Sanitization (NEW)
+
+- **Response sanitizer module** — New `responseSanitizer.ts` strips non-standard fields (`x_groq`, `usage_breakdown`, `service_tier`, etc.) from all OpenAI-format provider responses, fixing OpenAI Python SDK v1.83+ Pydantic validation failures that returned raw strings instead of parsed `ChatCompletion` objects
+- **Streaming chunk sanitization** — Passthrough streaming mode now sanitizes each SSE chunk in real-time via `sanitizeStreamingChunk()`, ensuring strict `chat.completion.chunk` schema compliance
+- **ID/Object/Usage normalization** — Ensures `id`, `object`, `created`, `model`, `choices`, and `usage` fields always exist with correct types
+- **Usage field cleanup** — Strips non-standard usage sub-fields, keeps only `prompt_tokens`, `completion_tokens`, `total_tokens`, and OpenAI detail fields
+
+### 🧠 Think Tag Extraction (NEW)
+
+- **`<think>` tag extraction** — Automatically extracts `<think>...</think>` blocks from thinking model responses (DeepSeek R1, Kimi K2 Thinking, etc.) into OpenAI's standard `reasoning_content` field
+- **Streaming think-tag stripping** — Real-time `<think>` extraction in passthrough SSE stream, preventing JSON parsing errors in downstream tools
+- **Preserves native reasoning** — Providers that already send `reasoning_content` natively (e.g., OpenAI o1) are not overwritten
+
+### 🔄 Role Normalization (NEW)
+
+- **`developer` → `system` conversion** — OpenAI's new `developer` role is automatically converted to `system` for all non-OpenAI providers (Claude, Gemini, Kiro, etc.)
+- **`system` → `user` merging** — For models that reject the `system` role (GLM, ERNIE), system messages are intelligently merged into the first user message with clear delimiters
+- **Model-aware normalization** — Uses model name prefix matching (`glm-*`, `ernie-*`) for compatibility decisions, avoiding hardcoded provider-level flags
+
+### 📐 Structured Output for Gemini (NEW)
+
+- **`response_format` → Gemini conversion** — OpenAI's `json_schema` structured output is now translated to Gemini's `responseMimeType` + `responseSchema` in the translator pipeline
+- **`json_object` support** — `response_format: { type: "json_object" }` maps to Gemini's `application/json` MIME type
+- **Schema cleanup** — Automatically removes unsupported JSON Schema keywords (`$schema`, `additionalProperties`) for Gemini compatibility
+
+### 📁 Files Added
+
+| File                                     | Purpose                                                                |
+| ---------------------------------------- | ---------------------------------------------------------------------- |
+| `open-sse/handlers/responseSanitizer.ts` | Response field stripping, think-tag extraction, ID/usage normalization |
+| `open-sse/services/roleNormalizer.ts`    | Developer→system, system→user role conversion pipeline                 |
+
+### 📁 Files Modified
+
+| File                                              | Change                                                                          |
+| ------------------------------------------------- | ------------------------------------------------------------------------------- |
+| `open-sse/handlers/chatCore.ts`                   | Integrated response sanitizer for non-streaming OpenAI responses                |
+| `open-sse/utils/stream.ts`                        | Integrated streaming chunk sanitizer + think-tag extraction in passthrough mode |
+| `open-sse/translator/index.ts`                    | Integrated role normalizer into the request translation pipeline                |
+| `open-sse/translator/request/openai-to-gemini.ts` | Added `response_format` → `responseMimeType`/`responseSchema` conversion        |
+
+---
+
 ## [1.0.0] — 2026-02-18
 
 > ### 🎉 First Major Release — OmniRoute 1.0
@@ -138,4 +187,5 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ---
 
+[1.1.0]: https://github.com/diegosouzapw/OmniRoute/releases/tag/v1.1.0
 [1.0.0]: https://github.com/diegosouzapw/OmniRoute/releases/tag/v1.0.0

README.md

@@ -340,7 +340,7 @@ Access via: WhatsApp, Telegram, Slack, Discord, iMessage, Signal...
 | ------------------------------- | ------------------------------------------------------------------------------ |
 | 🎯 **Smart 4-Tier Fallback**    | Auto-route: Subscription → API Key → Cheap → Free                              |
 | 📊 **Real-Time Quota Tracking** | Live token count + reset countdown per provider                                |
-| 🔄 **Format Translation**       | OpenAI ↔ Claude ↔ Gemini ↔ Cursor ↔ Kiro seamless                              |
+| 🔄 **Format Translation**       | OpenAI ↔ Claude ↔ Gemini ↔ Cursor ↔ Kiro seamless + response sanitization      |
 | 👥 **Multi-Account Support**    | Multiple accounts per provider with intelligent selection                      |
 | 🔄 **Auto Token Refresh**       | OAuth tokens refresh automatically with retry                                  |
 | 🎨 **Custom Combos**            | 6 strategies: fill-first, round-robin, p2c, random, least-used, cost-optimized |
@@ -429,6 +429,10 @@ Seamless translation between formats:
 - **OpenAI** ↔ **Claude** ↔ **Gemini** ↔ **OpenAI Responses**
 - Your CLI tool sends OpenAI format → OmniRoute translates → Provider receives native format
 - Works with any tool that supports custom OpenAI endpoints
+- **Response sanitization** — Strips non-standard fields for strict OpenAI SDK compatibility
+- **Role normalization** — `developer` → `system` for non-OpenAI; `system` → `user` for GLM/ERNIE models
+- **Think tag extraction** — `<think>` blocks → `reasoning_content` for thinking models
+- **Structured output** — `json_schema` → Gemini's `responseMimeType`/`responseSchema`
 
 ### 👥 Multi-Account Support
 

docs/ARCHITECTURE.md

@@ -1,6 +1,6 @@
 # OmniRoute Architecture
 
-_Last updated: 2026-02-17_
+_Last updated: 2026-02-18_
 
 ## Executive Summary
 
@@ -17,6 +17,9 @@ Core capabilities:
 - Embedding generation via `/v1/embeddings` (6 providers, 9 models)
 - Image generation via `/v1/images/generations` (4 providers, 9 models)
 - Think tag parsing (`<think>...</think>`) for reasoning models
+- Response sanitization for strict OpenAI SDK compatibility
+- Role normalization (developer→system, system→user) for cross-provider compatibility
+- Structured output conversion (json_schema → Gemini responseSchema)
 - Local persistence for providers, keys, aliases, combos, settings, pricing
 - Usage/cost tracking and request logging
 - Optional cloud sync for multi-device/state sync
@@ -180,6 +183,8 @@ Main flow modules:
 - Embedding provider registry: `open-sse/config/embeddingRegistry.ts`
 - Image generation handler: `open-sse/handlers/imageGeneration.ts`
 - Image provider registry: `open-sse/config/imageRegistry.ts`
+- Response sanitization: `open-sse/handlers/responseSanitizer.ts`
+- Role normalization: `open-sse/services/roleNormalizer.ts`
 
 Services (business logic):
 
@@ -647,6 +652,13 @@ Source Format → OpenAI (hub) → Target Format
 
 Translations are selected dynamically based on source payload shape and provider target format.
 
+Additional processing layers in the translation pipeline:
+
+- **Response sanitization** — Strips non-standard fields from OpenAI-format responses (both streaming and non-streaming) to ensure strict SDK compliance
+- **Role normalization** — Converts `developer` → `system` for non-OpenAI targets; merges `system` → `user` for models that reject the system role (GLM, ERNIE)
+- **Think tag extraction** — Parses `<think>...</think>` blocks from content into `reasoning_content` field
+- **Structured output** — Converts OpenAI `response_format.json_schema` to Gemini's `responseMimeType` + `responseSchema`
+
 ## Supported API Endpoints
 
 | Endpoint                                           | Format             | Handler                                              |

docs/TROUBLESHOOTING.md

@@ -177,6 +177,10 @@ Use **Dashboard → Translator** to debug format translation issues:
 - **Thinking tags not appearing** — Check if the target provider supports thinking and the thinking budget setting
 - **Tool calls dropping** — Some format translations may strip unsupported fields; verify in Playground mode
 - **System prompt missing** — Claude and Gemini handle system prompts differently; check translation output
+- **SDK returns raw string instead of object** — Fixed in v1.1.0: response sanitizer now strips non-standard fields (`x_groq`, `usage_breakdown`, etc.) that cause OpenAI SDK Pydantic validation failures
+- **GLM/ERNIE rejects `system` role** — Fixed in v1.1.0: role normalizer automatically merges system messages into user messages for incompatible models
+- **`developer` role not recognized** — Fixed in v1.1.0: automatically converted to `system` for non-OpenAI providers
+- **`json_schema` not working with Gemini** — Fixed in v1.1.0: `response_format` is now converted to Gemini's `responseMimeType` + `responseSchema`
 
 ---
 

next.config.mjs

@@ -2,6 +2,7 @@
 const nextConfig = {
   turbopack: {},
   output: "standalone",
+  serverExternalPackages: ["better-sqlite3"],
   transpilePackages: ["@omniroute/open-sse"],
   allowedDevOrigins: ["192.168.*"],
   typescript: {

open-sse/handlers/chatCore.ts

@@ -24,6 +24,7 @@ import { getExecutor } from "../executors/index.ts";
 import { translateNonStreamingResponse } from "./responseTranslator.ts";
 import { extractUsageFromResponse } from "./usageExtractor.ts";
 import { parseSSEToOpenAIResponse, parseSSEToResponsesOutput } from "./sseParser.ts";
+import { sanitizeOpenAIResponse } from "./responseSanitizer.ts";
 import {
   withRateLimit,
   updateFromHeaders,
@@ -471,10 +472,17 @@ export async function handleChatCore({
     }
 
     // Translate response to client's expected format (usually OpenAI)
-    const translatedResponse = needsTranslation(targetFormat, sourceFormat)
+    let translatedResponse = needsTranslation(targetFormat, sourceFormat)
       ? translateNonStreamingResponse(responseBody, targetFormat, sourceFormat)
       : responseBody;
 
+    // Sanitize response for OpenAI SDK compatibility
+    // Strips non-standard fields (x_groq, usage_breakdown, service_tier, etc.)
+    // Extracts <think> tags into reasoning_content
+    if (sourceFormat === FORMATS.OPENAI) {
+      translatedResponse = sanitizeOpenAIResponse(translatedResponse);
+    }
+
     // Add buffer and filter usage for client (to prevent CLI context errors)
     if (translatedResponse?.usage) {
       const buffered = addBufferToUsage(translatedResponse.usage);

open-sse/handlers/responseSanitizer.ts

@@ -0,0 +1,269 @@
+/**
+ * Response Sanitizer — Normalizes LLM responses to strict OpenAI SDK format.
+ *
+ * Fixes Issues:
+ * 1. Strips non-standard fields (x_groq, usage_breakdown, service_tier) that
+ *    break OpenAI Python SDK v1.83+ Pydantic validation (returns str instead of object)
+ * 2. Extracts <think> tags from thinking models into reasoning_content
+ * 3. Normalizes response id, object, and usage fields
+ * 4. Converts developer role → system for non-OpenAI providers
+ */
+
+// ── Standard OpenAI ChatCompletion fields ──────────────────────────────────
+const ALLOWED_TOP_LEVEL_FIELDS = new Set([
+  "id",
+  "object",
+  "created",
+  "model",
+  "choices",
+  "usage",
+  "system_fingerprint",
+]);
+
+const ALLOWED_USAGE_FIELDS = new Set([
+  "prompt_tokens",
+  "completion_tokens",
+  "total_tokens",
+  "prompt_tokens_details",
+  "completion_tokens_details",
+]);
+
+const ALLOWED_MESSAGE_FIELDS = new Set([
+  "role",
+  "content",
+  "tool_calls",
+  "function_call",
+  "refusal",
+  "reasoning_content",
+]);
+
+const ALLOWED_CHOICE_FIELDS = new Set(["index", "message", "delta", "finish_reason", "logprobs"]);
+
+// ── Think tag regex ────────────────────────────────────────────────────────
+// Matches <think>...</think> blocks (greedy, dotAll)
+const THINK_TAG_REGEX = /<think>([\s\S]*?)<\/think>/gi;
+
+/**
+ * Extract <think> blocks from text content and return separated parts.
+ * @returns {{ content: string, thinking: string | null }}
+ */
+export function extractThinkingFromContent(text: string): {
+  content: string;
+  thinking: string | null;
+} {
+  if (!text || typeof text !== "string") {
+    return { content: text || "", thinking: null };
+  }
+
+  const thinkingParts: string[] = [];
+  let hasThinkTags = false;
+
+  const cleaned = text.replace(THINK_TAG_REGEX, (_, thinkContent) => {
+    hasThinkTags = true;
+    const trimmed = thinkContent.trim();
+    if (trimmed) {
+      thinkingParts.push(trimmed);
+    }
+    return "";
+  });
+
+  if (!hasThinkTags) {
+    return { content: text, thinking: null };
+  }
+
+  return {
+    content: cleaned.trim(),
+    thinking: thinkingParts.length > 0 ? thinkingParts.join("\n\n") : null,
+  };
+}
+
+/**
+ * Sanitize a non-streaming OpenAI ChatCompletion response.
+ * Strips non-standard fields and normalizes required fields.
+ */
+export function sanitizeOpenAIResponse(body: any): any {
+  if (!body || typeof body !== "object") return body;
+
+  // Build sanitized response with only allowed top-level fields
+  const sanitized: Record<string, any> = {};
+
+  // Ensure required fields exist
+  sanitized.id = normalizeResponseId(body.id);
+  sanitized.object = body.object || "chat.completion";
+  sanitized.created = body.created || Math.floor(Date.now() / 1000);
+  sanitized.model = body.model || "unknown";
+
+  // Sanitize choices
+  if (Array.isArray(body.choices)) {
+    sanitized.choices = body.choices.map((choice: any, idx: number) => sanitizeChoice(choice, idx));
+  } else {
+    sanitized.choices = [];
+  }
+
+  // Sanitize usage
+  if (body.usage && typeof body.usage === "object") {
+    sanitized.usage = sanitizeUsage(body.usage);
+  }
+
+  // Keep system_fingerprint if present (it's a valid OpenAI field)
+  if (body.system_fingerprint) {
+    sanitized.system_fingerprint = body.system_fingerprint;
+  }
+
+  return sanitized;
+}
+
+/**
+ * Sanitize a single choice object.
+ */
+function sanitizeChoice(choice: any, defaultIndex: number): any {
+  const sanitized: Record<string, any> = {
+    index: choice.index ?? defaultIndex,
+    finish_reason: choice.finish_reason || null,
+  };
+
+  // Sanitize message (non-streaming) or delta (streaming)
+  if (choice.message) {
+    sanitized.message = sanitizeMessage(choice.message);
+  }
+  if (choice.delta) {
+    sanitized.delta = sanitizeMessage(choice.delta);
+  }
+
+  // Keep logprobs if present
+  if (choice.logprobs !== undefined) {
+    sanitized.logprobs = choice.logprobs;
+  }
+
+  return sanitized;
+}
+
+/**
+ * Sanitize a message object, extracting <think> tags if present.
+ */
+function sanitizeMessage(msg: any): any {
+  if (!msg || typeof msg !== "object") return msg;
+
+  const sanitized: Record<string, any> = {};
+
+  // Copy only allowed fields
+  if (msg.role) sanitized.role = msg.role;
+  if (msg.refusal !== undefined) sanitized.refusal = msg.refusal;
+
+  // Handle content — extract <think> tags
+  if (typeof msg.content === "string") {
+    const { content, thinking } = extractThinkingFromContent(msg.content);
+    sanitized.content = content;
+
+    // Set reasoning_content from <think> tags (if not already set)
+    if (thinking && !msg.reasoning_content) {
+      sanitized.reasoning_content = thinking;
+    }
+  } else if (msg.content !== undefined) {
+    sanitized.content = msg.content;
+  }
+
+  // Preserve existing reasoning_content (from providers that natively support it)
+  if (msg.reasoning_content && !sanitized.reasoning_content) {
+    sanitized.reasoning_content = msg.reasoning_content;
+  }
+
+  // Preserve tool_calls
+  if (msg.tool_calls) {
+    sanitized.tool_calls = msg.tool_calls;
+  }
+
+  // Preserve function_call (legacy)
+  if (msg.function_call) {
+    sanitized.function_call = msg.function_call;
+  }
+
+  return sanitized;
+}
+
+/**
+ * Sanitize usage object — keep only standard fields.
+ */
+function sanitizeUsage(usage: any): any {
+  if (!usage || typeof usage !== "object") return usage;
+
+  const sanitized: Record<string, any> = {};
+  for (const key of ALLOWED_USAGE_FIELDS) {
+    if (usage[key] !== undefined) {
+      sanitized[key] = usage[key];
+    }
+  }
+
+  // Ensure required fields
+  if (sanitized.prompt_tokens === undefined) sanitized.prompt_tokens = 0;
+  if (sanitized.completion_tokens === undefined) sanitized.completion_tokens = 0;
+  if (sanitized.total_tokens === undefined) {
+    sanitized.total_tokens = sanitized.prompt_tokens + sanitized.completion_tokens;
+  }
+
+  return sanitized;
+}
+
+/**
+ * Normalize response ID to use chatcmpl- prefix.
+ */
+function normalizeResponseId(id: any): string {
+  if (!id || typeof id !== "string") {
+    return `chatcmpl-${crypto.randomUUID().replace(/-/g, "").slice(0, 29)}`;
+  }
+  // Already correct format
+  if (id.startsWith("chatcmpl-")) return id;
+  // Keep custom IDs but don't break them
+  return id;
+}
+
+/**
+ * Sanitize a streaming SSE chunk for passthrough mode.
+ * Lighter than full sanitization — only strips problematic extra fields.
+ */
+export function sanitizeStreamingChunk(parsed: any): any {
+  if (!parsed || typeof parsed !== "object") return parsed;
+
+  // Build sanitized chunk
+  const sanitized: Record<string, any> = {};
+
+  // Keep only standard fields
+  if (parsed.id !== undefined) sanitized.id = parsed.id;
+  sanitized.object = parsed.object || "chat.completion.chunk";
+  if (parsed.created !== undefined) sanitized.created = parsed.created;
+  if (parsed.model !== undefined) sanitized.model = parsed.model;
+
+  // Sanitize choices with delta
+  if (Array.isArray(parsed.choices)) {
+    sanitized.choices = parsed.choices.map((choice: any) => {
+      const c: Record<string, any> = {
+        index: choice.index ?? 0,
+      };
+      if (choice.delta !== undefined) {
+        c.delta = {};
+        const delta = choice.delta;
+        if (delta.role !== undefined) c.delta.role = delta.role;
+        if (delta.content !== undefined) c.delta.content = delta.content;
+        if (delta.reasoning_content !== undefined)
+          c.delta.reasoning_content = delta.reasoning_content;
+        if (delta.tool_calls !== undefined) c.delta.tool_calls = delta.tool_calls;
+        if (delta.function_call !== undefined) c.delta.function_call = delta.function_call;
+      }
+      if (choice.finish_reason !== undefined) c.finish_reason = choice.finish_reason;
+      if (choice.logprobs !== undefined) c.logprobs = choice.logprobs;
+      return c;
+    });
+  }
+
+  // Sanitize usage if present
+  if (parsed.usage && typeof parsed.usage === "object") {
+    sanitized.usage = sanitizeUsage(parsed.usage);
+  }
+
+  // Keep system_fingerprint if present
+  if (parsed.system_fingerprint) {
+    sanitized.system_fingerprint = parsed.system_fingerprint;
+  }
+
+  return sanitized;
+}

open-sse/services/roleNormalizer.ts

@@ -0,0 +1,169 @@
+/**
+ * Role Normalizer — Converts message roles for provider compatibility.
+ *
+ * Fixes Issues:
+ * 1. GLM/ZhipuAI rejects `system` role → merged into first `user` message
+ * 2. OpenAI `developer` role not understood by non-OpenAI providers → normalized to `system`
+ * 3. Some providers don't support `system` role at all → prepended to user message
+ *
+ * Provider capability matrix is defined here rather than in the registry to
+ * avoid breaking changes to the existing RegistryEntry interface.
+ */
+
+// ── Provider capabilities ──────────────────────────────────────────────────
+
+/**
+ * Providers that do NOT support the `system` role in messages.
+ * For these, system messages are merged into the first user message.
+ *
+ * Note: This applies only to OpenAI-format passthrough providers.
+ * Claude and Gemini have their own system message handling in dedicated translators.
+ */
+const PROVIDERS_WITHOUT_SYSTEM_ROLE = new Set([
+  // Known to reject system role (from troubleshooting report)
+  // GLM uses Claude format, so this is handled through claude translator
+  // But if accessed through OpenAI-format providers like nvidia, it needs this:
+]);
+
+/**
+ * Models that are known to reject the `system` role regardless of provider.
+ * Uses prefix matching (e.g., "glm-" matches "glm-4.7", "glm-4.5", etc.)
+ */
+const MODELS_WITHOUT_SYSTEM_ROLE = [
+  "glm-", // ZhipuAI GLM models
+  "ernie-", // Baidu ERNIE models
+];
+
+/**
+ * Check if a provider+model combo supports the system role.
+ */
+function supportsSystemRole(provider: string, model: string): boolean {
+  if (PROVIDERS_WITHOUT_SYSTEM_ROLE.has(provider)) return false;
+
+  const modelLower = (model || "").toLowerCase();
+  for (const prefix of MODELS_WITHOUT_SYSTEM_ROLE) {
+    if (modelLower.startsWith(prefix)) return false;
+  }
+
+  return true;
+}
+
+/**
+ * Normalize the `developer` role to `system` for non-OpenAI providers.
+ * OpenAI introduced `developer` as a replacement for `system` in newer models,
+ * but most other providers still expect `system`.
+ *
+ * @param messages - Array of messages
+ * @param targetFormat - The target format (e.g., "openai", "claude", "gemini")
+ * @returns Modified messages array
+ */
+export function normalizeDeveloperRole(messages: any[], targetFormat: string): any[] {
+  if (!Array.isArray(messages)) return messages;
+
+  // For OpenAI format, keep developer role as-is (it's valid)
+  // For all other formats, convert developer → system
+  if (targetFormat === "openai") return messages;
+
+  return messages.map((msg) => {
+    if (msg.role === "developer") {
+      return { ...msg, role: "system" };
+    }
+    return msg;
+  });
+}
+
+/**
+ * Convert `system` messages to user messages for providers that don't support
+ * the system role. The system content is prepended to the first user message
+ * with a clear delimiter.
+ *
+ * @param messages - Array of messages
+ * @param provider - Provider name
+ * @param model - Model name
+ * @returns Modified messages array
+ */
+export function normalizeSystemRole(messages: any[], provider: string, model: string): any[] {
+  if (!Array.isArray(messages) || messages.length === 0) return messages;
+  if (supportsSystemRole(provider, model)) return messages;
+
+  // Extract system messages
+  const systemMessages = messages.filter((m) => m.role === "system" || m.role === "developer");
+  if (systemMessages.length === 0) return messages;
+
+  // Build system content string
+  const systemContent = systemMessages
+    .map((m) => {
+      if (typeof m.content === "string") return m.content;
+      if (Array.isArray(m.content)) {
+        return m.content
+          .filter((c: any) => c.type === "text")
+          .map((c: any) => c.text)
+          .join("\n");
+      }
+      return "";
+    })
+    .filter(Boolean)
+    .join("\n\n");
+
+  if (!systemContent) {
+    return messages.filter((m) => m.role !== "system" && m.role !== "developer");
+  }
+
+  // Remove system messages and merge into first user message
+  const nonSystemMessages = messages.filter((m) => m.role !== "system" && m.role !== "developer");
+
+  // Find first user message and prepend system content
+  const firstUserIdx = nonSystemMessages.findIndex((m) => m.role === "user");
+  if (firstUserIdx >= 0) {
+    const userMsg = nonSystemMessages[firstUserIdx];
+    const userContent =
+      typeof userMsg.content === "string"
+        ? userMsg.content
+        : Array.isArray(userMsg.content)
+          ? userMsg.content
+              .filter((c: any) => c.type === "text")
+              .map((c: any) => c.text)
+              .join("\n")
+          : "";
+
+    nonSystemMessages[firstUserIdx] = {
+      ...userMsg,
+      content: `[System Instructions]\n${systemContent}\n\n[User Message]\n${userContent}`,
+    };
+  } else {
+    // No user message found — insert as a user message at the beginning
+    nonSystemMessages.unshift({
+      role: "user",
+      content: `[System Instructions]\n${systemContent}`,
+    });
+  }
+
+  return nonSystemMessages;
+}
+
+/**
+ * Full role normalization pipeline.
+ * Call this before sending the request to the provider.
+ *
+ * @param messages - Array of messages
+ * @param provider - Provider name/id
+ * @param model - Model name
+ * @param targetFormat - Target API format
+ * @returns Normalized messages array
+ */
+export function normalizeRoles(
+  messages: any[],
+  provider: string,
+  model: string,
+  targetFormat: string
+): any[] {
+  if (!Array.isArray(messages)) return messages;
+
+  // Step 1: Normalize developer → system (for non-OpenAI formats)
+  let result = normalizeDeveloperRole(messages, targetFormat);
+
+  // Step 2: Normalize system → user (for providers that don't support system role)
+  result = normalizeSystemRole(result, provider, model);
+
+  return result;
+}

open-sse/translator/index.ts

@@ -4,6 +4,7 @@ import { prepareClaudeRequest } from "./helpers/claudeHelper.ts";
 import { filterToOpenAIFormat } from "./helpers/openaiHelper.ts";
 import { normalizeThinkingConfig } from "../services/provider.ts";
 import { applyThinkingBudget } from "../services/thinkingBudget.ts";
+import { normalizeRoles } from "../services/roleNormalizer.ts";
 
 // Registry for translators.
 // NOTE: translator modules import this file and call register() at module-load time.
@@ -132,6 +133,11 @@ export function translateRequest(
   // Fix missing tool responses (insert empty tool_result if needed)
   fixMissingToolResponses(result);
 
+  // Normalize roles: developer→system for non-OpenAI, system→user for incompatible models
+  if (result.messages && Array.isArray(result.messages)) {
+    result.messages = normalizeRoles(result.messages, provider || "", model || "", targetFormat);
+  }
+
   // If same format, skip translation steps
   if (sourceFormat !== targetFormat) {
     // Check for direct translation path first (e.g., Claude → Gemini)

open-sse/translator/request/openai-to-gemini.ts

@@ -199,6 +199,24 @@ function openaiToGeminiBase(model, body, stream) {
     }
   }
 
+  // Convert response_format to Gemini's responseMimeType/responseSchema
+  if (body.response_format) {
+    if (body.response_format.type === "json_schema" && body.response_format.json_schema) {
+      result.generationConfig.responseMimeType = "application/json";
+      // Extract the schema (may be nested under .schema key)
+      const schema = body.response_format.json_schema.schema || body.response_format.json_schema;
+      if (schema && typeof schema === "object") {
+        // Remove unsupported keywords for Gemini (it uses a subset of JSON Schema)
+        const { $schema, additionalProperties, ...cleanSchema } = schema;
+        result.generationConfig.responseSchema = cleanSchema;
+      }
+    } else if (body.response_format.type === "json_object") {
+      result.generationConfig.responseMimeType = "application/json";
+    } else if (body.response_format.type === "text") {
+      result.generationConfig.responseMimeType = "text/plain";
+    }
+  }
+
   return result;
 }
 

open-sse/utils/stream.ts

@@ -12,6 +12,10 @@ import {
 } from "./usageTracking.ts";
 import { parseSSELine, hasValuableContent, fixInvalidId, formatSSE } from "./streamHelpers.ts";
 import { STREAM_IDLE_TIMEOUT_MS, HTTP_STATUS } from "../config/constants.ts";
+import {
+  sanitizeStreamingChunk,
+  extractThinkingFromContent,
+} from "../handlers/responseSanitizer.ts";
 
 export { COLORS, formatSSE };
 
@@ -130,7 +134,10 @@ export function createSSEStream(options: any = {}) {
 
             if (trimmed.startsWith("data:") && trimmed.slice(5).trim() !== "[DONE]") {
               try {
-                const parsed = JSON.parse(trimmed.slice(5).trim());
+                let parsed = JSON.parse(trimmed.slice(5).trim());
+
+                // Sanitize: strip non-standard fields for OpenAI SDK compatibility
+                parsed = sanitizeStreamingChunk(parsed);
 
                 const idFixed = fixInvalidId(parsed);
 
@@ -139,6 +146,16 @@ export function createSSEStream(options: any = {}) {
                 }
 
                 const delta = parsed.choices?.[0]?.delta;
+
+                // Extract <think> tags from streaming content
+                if (delta?.content && typeof delta.content === "string") {
+                  const { content, thinking } = extractThinkingFromContent(delta.content);
+                  delta.content = content;
+                  if (thinking && !delta.reasoning_content) {
+                    delta.reasoning_content = thinking;
+                  }
+                }
+
                 const content = delta?.content || delta?.reasoning_content;
                 if (content && typeof content === "string") {
                   totalContentLength += content.length;