OpenAI GPT-5 improvements (#9)

A series of fixes for making GPT-5 reliable and effective with anyclaude.

## UX changes

- Converts opaque OpenAI service errors into 429s so CC natively retries instead of failing. These are very common.
- Rich debugging support via `ANYCLAUDE_DEBUG`
- Supports specifying reasoning effort and service tier 

## Codebase

- Added CI

## Remaining issues

- GPT-5 often fails to use the native tool calls. These failures seems intermittent.

.github/workflows/ci.yml

@@ -0,0 +1,47 @@
+name: CI
+
+on:
+  push:
+    branches: [ main, master ]
+  pull_request:
+    branches: [ main, master ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - uses: actions/checkout@v4
+    
+    - name: Setup Bun
+      uses: oven-sh/setup-bun@v2
+      with:
+        bun-version: latest
+    
+    - name: Cache dependencies
+      uses: actions/cache@v4
+      with:
+        path: |
+          ~/.bun/install/cache
+          node_modules
+        key: ${{ runner.os }}-bun-${{ hashFiles('**/bun.lockb') }}
+        restore-keys: |
+          ${{ runner.os }}-bun-
+    
+    - name: Install dependencies
+      run: bun install --frozen-lockfile
+    
+    - name: Run tests
+      run: bun test
+    
+    - name: Type check
+      run: bun run typecheck
+    
+    - name: Build
+      run: bun run build
+    
+    - name: Verify build output
+      run: |
+        test -f dist/main.js
+        test -x dist/main.js
+        head -n 1 dist/main.js | grep -q "#!/usr/bin/env node"

CLAUDE.md

@@ -34,6 +34,9 @@ bun install
 # Build the project (creates dist/main.js with shebang)
 bun run build
 
+# Run the built binary
+bun run ./dist/main.js
+
 # The build command:
 # 1. Compiles TypeScript to CommonJS for Node.js compatibility
 # 2. Adds Node shebang for CLI execution
@@ -64,3 +67,6 @@ Required for each provider:
 Special modes:
 
 - `PROXY_ONLY=true`: Run proxy server without spawning Claude Code
+- `ANYCLAUDE_DEBUG=1|2`: Enable debug logging (1=basic, 2=verbose)
+
+- OpenAI's gpt-5 was released in August 2025

README.md

@@ -23,6 +23,22 @@ $ anyclaude --model openai/gpt-5-mini
 
 Switch models in the Claude UI with `/model openai/gpt-5-mini`.
 
+### GPT-5 Support
+
+Use --reasoning-effort (alias: -e) to control OpenAI reasoning.effort. Allowed values: minimal, low, medium, high.
+
+```sh
+anyclaude --model openai/gpt-5-mini -e high
+```
+
+Use --service-tier (alias: -t) to control OpenAI service tier. Allowed values: flex, priority.
+
+```sh
+anyclaude --model openai/gpt-5-mini -t priority
+```
+
+Note these flags may be extended to other providers in the future.
+
 ## FAQ
 
 ### What providers are supported?

bun.lock

@@ -3,6 +3,10 @@
   "workspaces": {
     "": {
       "name": "openclaude",
+      "dependencies": {
+        "@types/yargs-parser": "^21.0.3",
+        "yargs-parser": "^22.0.0",
+      },
       "devDependencies": {
         "@ai-sdk/anthropic": "^2.0.1",
         "@ai-sdk/azure": "^2.0.6",
@@ -49,6 +53,8 @@
 
     "@types/node": ["@types/node@22.15.21", "", { "dependencies": { "undici-types": "~6.21.0" } }, "sha512-EV/37Td6c+MgKAbkcLG6vqZ2zEYHD7bvSrzqqs2RIhbA6w3x+Dqz8MZM3sP6kGTeLrdoOgKZe+Xja7tUB2DNkQ=="],
 
+    "@types/yargs-parser": ["@types/yargs-parser@21.0.3", "", {}, "sha512-I4q9QU9MQv4oEOz4tAHJtNz1cwuLxn2F3xcc2iV5WdqLPpUnj30aUuxt1mAxYTG+oe8CZMV/+6rU4S4gRDzqtQ=="],
+
     "ai": ["ai@5.0.8", "", { "dependencies": { "@ai-sdk/gateway": "1.0.4", "@ai-sdk/provider": "2.0.0", "@ai-sdk/provider-utils": "3.0.1", "@opentelemetry/api": "1.9.0" }, "peerDependencies": { "zod": "^3.25.76 || ^4" } }, "sha512-qbnhj046UvG30V1S5WhjBn+RBGEAmi8PSZWqMhRsE3EPxvO5BcePXTZFA23e9MYyWS9zr4Vm8Mv3wQXwLmtIBw=="],
 
     "bun-types": ["bun-types@1.2.14", "", { "dependencies": { "@types/node": "*" } }, "sha512-Kuh4Ub28ucMRWeiUUWMHsT9Wcbr4H3kLIO72RZZElSDxSu7vpetRvxIUDUaW6QtaIeixIpm7OXtNnZPf82EzwA=="],
@@ -61,6 +67,8 @@
 
     "undici-types": ["undici-types@6.21.0", "", {}, "sha512-iwDZqg0QAGrg9Rav5H4n0M64c3mkR59cJ6wQp+7C4nI0gsmExaedaYLNO44eT4AtBBwjbTiGPMlt2Md0T9H9JQ=="],
 
+    "yargs-parser": ["yargs-parser@22.0.0", "", {}, "sha512-rwu/ClNdSMpkSrUb+d6BRsSkLUq1fmfsY6TOpYzTwvwkg1/NRG85KBy3kq++A8LKQwX6lsu+aWad+2khvuXrqw=="],
+
     "zod": ["zod@3.25.76", "", {}, "sha512-gzUt/qt81nXsFGKIFcC3YnfEAx5NkunCfnDlvuBSSFS02bcXu4Lmea0AFIUwbLWxWPx3d9p8S5QoaujKcNQxcQ=="],
 
     "zod-to-json-schema": ["zod-to-json-schema@3.24.5", "", { "peerDependencies": { "zod": "^3.24.1" } }, "sha512-/AuWwMP+YqiPbsJx5D6TfgRTc4kTLjsh5SOcd4bLsfUg2RcEXrFMJl1DGgdHy2aCfsIA/cr/1JM0xcB2GZji8g=="],

package.json

@@ -31,6 +31,12 @@
   "description": "Run Claude Code with OpenAI, Google, xAI, and others.",
   "license": "MIT",
   "scripts": {
-    "build": "bun build --target node --outfile dist/main.js ./src/main.ts --format cjs --external ai --external @ai-sdk/* --external zod && node -e \"const fs=require('fs');const p='dist/main.js';fs.writeFileSync(p,'#!/usr/bin/env node\\n'+fs.readFileSync(p,'utf8'))\" && chmod +x dist/main.js"
+    "build": "bun build --target node --outfile dist/main.js ./src/main.ts --format cjs --external ai --external @ai-sdk/* --external zod && node -e \"const fs=require('fs');const p='dist/main.js';fs.writeFileSync(p,'#!/usr/bin/env node\\n'+fs.readFileSync(p,'utf8'))\" && chmod +x dist/main.js",
+    "test": "bun test",
+    "typecheck": "tsc --noEmit"
+  },
+  "dependencies": {
+    "@types/yargs-parser": "^21.0.3",
+    "yargs-parser": "^22.0.0"
   }
 }

src/anthropic-proxy.ts

@@ -11,6 +11,15 @@ import {
 import { convertToAnthropicStream } from "./convert-to-anthropic-stream";
 import { convertToLanguageModelMessage } from "./convert-to-language-model-prompt";
 import { providerizeSchema } from "./json-schema";
+import { 
+  writeDebugToTempFile, 
+  logDebugError, 
+  displayDebugStartup,
+  isDebugEnabled,
+  isVerboseDebugEnabled,
+  queueErrorMessage,
+  debug
+} from "./debug";
 
 export type CreateAnthropicProxyOptions = {
   providers: Record<string, ProviderV2>;
@@ -25,6 +34,9 @@ export const createAnthropicProxy = ({
   port,
   providers,
 }: CreateAnthropicProxyOptions): string => {
+  // Log debug status on startup
+  displayDebugStartup();
+  
   const proxy = http
     .createServer((req, res) => {
       if (!req.url) {
@@ -42,6 +54,10 @@ export const createAnthropicProxy = ({
       const proxyToAnthropic = (body?: AnthropicMessagesRequest) => {
         delete req.headers["host"];
 
+        const requestBody = body ? JSON.stringify(body) : null;
+        const chunks: Buffer[] = [];
+        const responseChunks: Buffer[] = [];
+
         const proxy = https.request(
           {
             host: "api.anthropic.com",
@@ -50,17 +66,66 @@ export const createAnthropicProxy = ({
             headers: req.headers,
           },
           (proxiedRes) => {
-            res.writeHead(proxiedRes.statusCode ?? 500, proxiedRes.headers);
+            const statusCode = proxiedRes.statusCode ?? 500;
+            
+            // Collect response data for debugging
+            proxiedRes.on('data', (chunk) => {
+              responseChunks.push(chunk);
+            });
+
+            proxiedRes.on('end', () => {
+              // Write debug info to temp file for 4xx errors (except 429)
+              if (statusCode >= 400 && statusCode < 500 && statusCode !== 429) {
+                const requestBodyToLog = requestBody 
+                  ? JSON.parse(requestBody)
+                  : chunks.length > 0 
+                    ? (() => {
+                        try {
+                          return JSON.parse(Buffer.concat(chunks).toString());
+                        } catch {
+                          return Buffer.concat(chunks).toString();
+                        }
+                      })()
+                    : null;
+
+                const responseBody = Buffer.concat(responseChunks).toString();
+                const debugFile = writeDebugToTempFile(
+                  statusCode,
+                  {
+                    method: req.method,
+                    url: req.url,
+                    headers: req.headers,
+                    body: requestBodyToLog,
+                  },
+                  {
+                    statusCode,
+                    headers: proxiedRes.headers,
+                    body: responseBody,
+                  }
+                );
+
+                if (debugFile) {
+                  logDebugError("HTTP", statusCode, debugFile);
+                }
+              }
+            });
+
+            res.writeHead(statusCode, proxiedRes.headers);
             proxiedRes.pipe(res, {
               end: true,
             });
           }
         );
-        if (body) {
-          proxy.end(JSON.stringify(body));
+
+        if (requestBody) {
+          proxy.end(requestBody);
         } else {
-          req.pipe(proxy, {
-            end: true,
+          req.on('data', (chunk) => {
+            chunks.push(chunk);
+            proxy.write(chunk);
+          });
+          req.on('end', () => {
+            proxy.end();
           });
         }
       };
@@ -176,14 +241,75 @@ export const createAnthropicProxy = ({
             );
           },
           onError: ({ error }) => {
+            let statusCode = 400; // Provider errors are returned as 400
+            let transformedError = error;
+            
+            // Check if this is an OpenAI server error that we should transform
+            const isOpenAIServerError = providerName === 'openai' && 
+              error && typeof error === 'object' && 
+              'error' in error && (error as any).error?.code === 'server_error';
+            
+            if (isOpenAIServerError) {
+              debug(1, `OpenAI server error detected in onError for ${model}. Transforming to 429 to trigger retry...`);
+              // Transform to rate limit error to trigger retry
+              statusCode = 429;
+              transformedError = {
+                type: "error",
+                error: {
+                  type: "rate_limit_error", 
+                  message: "OpenAI server temporarily unavailable. Please retry your request."
+                }
+              };
+            }
+            
+            // Write comprehensive debug info to temp file
+            const debugFile = writeDebugToTempFile(
+              statusCode,
+              {
+                method: "POST",
+                url: req.url,
+                headers: req.headers,
+                body: body,
+              },
+              {
+                statusCode,
+                headers: { "Content-Type": "application/json" },
+                body: JSON.stringify({
+                  provider: providerName,
+                  model: model,
+                  originalError: error instanceof Error ? {
+                    message: error.message,
+                    stack: error.stack,
+                    name: error.name,
+                  } : error,
+                  error: transformedError instanceof Error ? {
+                    message: transformedError.message,
+                    stack: transformedError.stack,
+                    name: transformedError.name,
+                  } : transformedError,
+                  wasTransformed: isOpenAIServerError,
+                  _debugInfo: {
+                    requestSize: JSON.stringify(body).length,
+                    toolCount: body.tools?.length || 0,
+                    systemPromptLength: body.system?.reduce((acc, s) => acc + s.text.length, 0) || 0,
+                    messageCount: body.messages.length
+                  }
+                }),
+              }
+            );
+
+            if (debugFile) {
+              logDebugError("Provider", statusCode, debugFile, { provider: providerName, model });
+            }
+
             res
-              .writeHead(400, {
+              .writeHead(statusCode, {
                 "Content-Type": "application/json",
               })
               .end(
                 JSON.stringify({
                   type: "error",
-                  error: error instanceof Error ? error.message : error,
+                  error: transformedError instanceof Error ? transformedError.message : transformedError,
                 })
               );
           },
@@ -199,14 +325,99 @@ export const createAnthropicProxy = ({
           // We already send the error to the client.
         });
 
+        // Collect all stream chunks for debugging if enabled
+        const streamChunks: any[] = [];
+        const startTime = Date.now();
+
         await convertToAnthropicStream(stream.fullStream).pipeTo(
           new WritableStream({
             write(chunk) {
+              // Collect chunks for debug dump (only in verbose mode to save memory)
+              if (isVerboseDebugEnabled()) {
+                streamChunks.push({
+                  timestamp: Date.now() - startTime,
+                  chunk: chunk
+                });
+              }
+              
+              // Check for streaming errors and log them (but don't interrupt the stream)
+              if (chunk.type === "error") {
+                // Store original error for debugging
+                const originalError = { ...chunk };
+                
+                // Check if this is an OpenAI server error (any sequence)
+                const isOpenAIServerError = providerName === 'openai' && 
+                  (chunk as any).error?.code === 'server_error';
+                
+                if (isOpenAIServerError) {
+                  debug(1, `OpenAI server error detected for ${model} at sequence ${(chunk as any).sequence_number}. This is a known transient issue with OpenAI.`);
+                  debug(1, `Transforming to 429 rate limit error to trigger Claude Code's automatic retry...`);
+                  
+                  // Transform OpenAI server errors to 429 rate limit errors
+                  // This should trigger Claude Code's built-in retry mechanism
+                  chunk = {
+                    type: "error",
+                    sequence_number: (chunk as any).sequence_number,
+                    error: {
+                      type: "rate_limit_error" as any,
+                      code: "rate_limit_error",
+                      message: "OpenAI server temporarily unavailable. Please retry your request.",
+                      param: null
+                    }
+                  } as any;
+                } else {
+                  // Log other errors normally
+                  debug(1, `Streaming error chunk detected for ${providerName}/${model} at ${Date.now() - startTime}ms:`, chunk);
+                }
+                
+                // Write comprehensive debug info including full stream dump
+                const debugFile = writeDebugToTempFile(
+                  400, // Streaming errors are sent as 400
+                  {
+                    method: "POST",
+                    url: req.url,
+                    headers: req.headers,
+                    body: body,
+                  },
+                  {
+                    statusCode: 400,
+                    headers: { "Content-Type": "text/event-stream" },
+                    body: JSON.stringify({
+                      provider: providerName,
+                      model: model,
+                      streamingError: originalError,
+                      transformedError: isOpenAIServerError ? chunk : null,
+                      wasTransformed: isOpenAIServerError,
+                      fullChunk: JSON.stringify(originalError),
+                      streamDuration: Date.now() - startTime,
+                      streamChunkCount: streamChunks.length,
+                      allStreamChunks: streamChunks,
+                      _debugInfo: {
+                        requestSize: JSON.stringify(body).length,
+                        toolCount: body.tools?.length || 0,
+                        systemPromptLength: body.system?.reduce((acc, s) => acc + s.text.length, 0) || 0,
+                        messageCount: body.messages.length
+                      }
+                    }),
+                  }
+                );
+
+                if (debugFile) {
+                  logDebugError("Streaming", 400, debugFile, { provider: providerName, model });
+                } else if (isDebugEnabled()) {
+                  queueErrorMessage(`Failed to write debug file for streaming error`);
+                }
+              }
+              
+              // Write all chunks (including errors) to the stream - matching original behavior
               res.write(
                 `event: ${chunk.type}\ndata: ${JSON.stringify(chunk)}\n\n`
               );
             },
             close() {
+              if (streamChunks.length > 0) {
+                debug(2, `Stream completed for ${providerName}/${model}: ${streamChunks.length} chunks in ${Date.now() - startTime}ms`);
+              }
               res.end();
             },
           })

src/convert-anthropic-messages.test.ts

@@ -0,0 +1,175 @@
+import { describe, expect, it } from "bun:test";
+import { convertToAnthropicMessagesPrompt } from "./convert-anthropic-messages";
+import type { LanguageModelV2Prompt } from "@ai-sdk/provider";
+
+describe("convertToAnthropicMessagesPrompt", () => {
+  describe("duplicate tool call filtering", () => {
+    it("should filter out duplicate tool calls with the same ID", () => {
+      const prompt: LanguageModelV2Prompt = [
+        {
+          role: "assistant",
+          content: [
+            {
+              type: "tool-call",
+              toolCallId: "call_123",
+              toolName: "TodoWrite",
+              input: { todos: ["item1", "item2"] },
+            },
+            {
+              type: "tool-call",
+              toolCallId: "call_123", // Duplicate ID
+              toolName: "TodoWrite",
+              input: {}, // Empty input
+            },
+          ],
+        },
+      ];
+
+      const result = convertToAnthropicMessagesPrompt({
+        prompt,
+        sendReasoning: false,
+        warnings: [],
+      });
+
+      // Should only have one tool_use in the output
+      const assistantMessage = result.prompt.messages[0];
+      expect(assistantMessage?.role).toBe("assistant");
+      
+      if (assistantMessage?.role === "assistant") {
+        const toolUses = assistantMessage.content.filter(
+          (c) => c.type === "tool_use"
+        );
+        expect(toolUses).toHaveLength(1);
+        expect(toolUses[0]?.id).toBe("call_123");
+        expect(toolUses[0]?.name).toBe("TodoWrite");
+        expect(toolUses[0]?.input).toEqual({ todos: ["item1", "item2"] });
+      }
+    });
+
+    it("should keep tool calls with different IDs", () => {
+      const prompt: LanguageModelV2Prompt = [
+        {
+          role: "assistant",
+          content: [
+            {
+              type: "tool-call",
+              toolCallId: "call_123",
+              toolName: "TodoWrite",
+              input: { todos: ["item1"] },
+            },
+            {
+              type: "tool-call",
+              toolCallId: "call_456", // Different ID
+              toolName: "Read",
+              input: { file: "test.txt" },
+            },
+          ],
+        },
+      ];
+
+      const result = convertToAnthropicMessagesPrompt({
+        prompt,
+        sendReasoning: false,
+        warnings: [],
+      });
+
+      const assistantMessage = result.prompt.messages[0];
+      expect(assistantMessage?.role).toBe("assistant");
+      
+      if (assistantMessage?.role === "assistant") {
+        const toolUses = assistantMessage.content.filter(
+          (c) => c.type === "tool_use"
+        );
+        expect(toolUses).toHaveLength(2);
+        expect(toolUses[0]?.id).toBe("call_123");
+        expect(toolUses[0]?.name).toBe("TodoWrite");
+        expect(toolUses[1]?.id).toBe("call_456");
+        expect(toolUses[1]?.name).toBe("Read");
+      }
+    });
+
+    it("should handle mixed content with duplicate tool calls", () => {
+      const prompt: LanguageModelV2Prompt = [
+        {
+          role: "assistant",
+          content: [
+            {
+              type: "text",
+              text: "Let me help you with that.",
+            },
+            {
+              type: "tool-call",
+              toolCallId: "call_abc",
+              toolName: "Search",
+              input: { query: "test" },
+            },
+            {
+              type: "text",
+              text: "Processing...",
+            },
+            {
+              type: "tool-call",
+              toolCallId: "call_abc", // Duplicate ID
+              toolName: "Search",
+              input: { query: "different" },
+            },
+          ],
+        },
+      ];
+
+      const result = convertToAnthropicMessagesPrompt({
+        prompt,
+        sendReasoning: false,
+        warnings: [],
+      });
+
+      const assistantMessage = result.prompt.messages[0];
+      expect(assistantMessage?.role).toBe("assistant");
+      
+      if (assistantMessage?.role === "assistant") {
+        // Should have 2 text blocks and 1 tool_use (duplicate filtered)
+        const textBlocks = assistantMessage.content.filter(
+          (c) => c.type === "text"
+        );
+        const toolUses = assistantMessage.content.filter(
+          (c) => c.type === "tool_use"
+        );
+        
+        expect(textBlocks).toHaveLength(2);
+        expect(toolUses).toHaveLength(1);
+        expect(toolUses[0]?.id).toBe("call_abc");
+        expect(toolUses[0]?.input).toEqual({ query: "test" }); // Should keep the first one
+      }
+    });
+
+    it("should handle empty tool call arrays correctly", () => {
+      const prompt: LanguageModelV2Prompt = [
+        {
+          role: "assistant",
+          content: [
+            {
+              type: "text",
+              text: "No tools needed.",
+            },
+          ],
+        },
+      ];
+
+      const result = convertToAnthropicMessagesPrompt({
+        prompt,
+        sendReasoning: false,
+        warnings: [],
+      });
+
+      const assistantMessage = result.prompt.messages[0];
+      expect(assistantMessage?.role).toBe("assistant");
+      
+      if (assistantMessage?.role === "assistant") {
+        const toolUses = assistantMessage.content.filter(
+          (c) => c.type === "tool_use"
+        );
+        expect(toolUses).toHaveLength(0);
+      }
+    });
+  });
+});

src/convert-anthropic-messages.ts

@@ -255,13 +255,21 @@ export function convertToAnthropicMessagesPrompt({
               }
 
               case "tool-call": {
-                anthropicContent.push({
-                  type: "tool_use",
-                  id: part.toolCallId,
-                  name: part.toolName,
-                  input: part.input,
-                  cache_control: cacheControl,
-                });
+                // Check if we already have a tool call with this ID
+                const existingToolCall = anthropicContent.find(
+                  (c) => c.type === "tool_use" && c.id === part.toolCallId
+                );
+                
+                // Skip duplicate tool calls (OpenAI doesn't allow duplicate IDs)
+                if (!existingToolCall) {
+                  anthropicContent.push({
+                    type: "tool_use",
+                    id: part.toolCallId,
+                    name: part.toolName,
+                    input: part.input,
+                    cache_control: cacheControl,
+                  });
+                }
                 break;
               }
             }

src/debug.ts

@@ -0,0 +1,186 @@
+import * as fs from "fs";
+import * as path from "path";
+import * as os from "os";
+
+// Store error messages to display later
+let pendingErrorMessages: string[] = [];
+
+export interface DebugInfo {
+  statusCode: number;
+  request: {
+    method?: string;
+    url?: string;
+    headers: any;
+    body: any;
+  };
+  response?: {
+    statusCode: number;
+    headers: any;
+    body: string;
+  };
+}
+
+/**
+ * Write debug info to a temp file when ANYCLAUDE_DEBUG is set
+ * @returns The path to the debug file, or null if not written
+ */
+export function writeDebugToTempFile(
+  statusCode: number,
+  request: DebugInfo["request"],
+  response?: DebugInfo["response"]
+): string | null {
+  // Log 4xx errors (except 429) when ANYCLAUDE_DEBUG is set
+  const debugEnabled = process.env.ANYCLAUDE_DEBUG;
+  
+  if (!debugEnabled || statusCode === 429 || statusCode < 400 || statusCode >= 500) {
+    return null;
+  }
+
+  try {
+    const tmpDir = os.tmpdir();
+    const timestamp = Date.now();
+    const randomId = Math.random().toString(36).substring(2, 8);
+    const filename = `anyclaude-debug-${timestamp}-${randomId}.json`;
+    const filepath = path.join(tmpDir, filename);
+
+    const debugData = {
+      timestamp: new Date().toISOString(),
+      request: {
+        method: request.method,
+        url: request.url,
+        headers: request.headers,
+        body: request.body,
+      },
+      response: response || null,
+    };
+
+    fs.writeFileSync(filepath, JSON.stringify(debugData, null, 2), 'utf8');
+    
+    // Also write a simpler error log file that's easier to tail
+    const errorLogPath = path.join(tmpDir, 'anyclaude-errors.log');
+    const errorMessage = `[${new Date().toISOString()}] HTTP ${statusCode} - Debug: ${filepath}\n`;
+    fs.appendFileSync(errorLogPath, errorMessage, 'utf8');
+    
+    return filepath;
+  } catch (error) {
+    console.error("[ANYCLAUDE DEBUG] Failed to write debug file:", error);
+    return null;
+  }
+}
+
+/**
+ * Queue an error message to be displayed later
+ */
+export function queueErrorMessage(message: string): void {
+  pendingErrorMessages.push(message);
+  // Display after a short delay to avoid being overwritten
+  setTimeout(displayPendingErrors, 500);
+}
+
+/**
+ * Display pending error messages to stderr with formatting
+ */
+function displayPendingErrors(): void {
+  if (pendingErrorMessages.length > 0) {
+    // Use stderr and add newlines to separate from Claude's output
+    process.stderr.write('\n\n═══════════════════════════════════════\n');
+    process.stderr.write('ANYCLAUDE DEBUG - Errors detected:\n');
+    process.stderr.write('═══════════════════════════════════════\n');
+    pendingErrorMessages.forEach(msg => {
+      process.stderr.write(msg + '\n');
+    });
+    process.stderr.write('═══════════════════════════════════════\n\n');
+    pendingErrorMessages = [];
+  }
+}
+
+/**
+ * Log a debug error and queue it for display
+ */
+export function logDebugError(
+  type: "HTTP" | "Provider" | "Streaming",
+  statusCode: number,
+  debugFile: string | null,
+  context?: { provider?: string; model?: string }
+): void {
+  if (!debugFile) return;
+  
+  let message = `${type} error`;
+  if (context?.provider && context?.model) {
+    message += ` (${context.provider}/${context.model})`;
+  } else if (statusCode) {
+    message += ` ${statusCode}`;
+  }
+  message += ` - Debug info written to: ${debugFile}`;
+  
+  queueErrorMessage(message);
+}
+
+/**
+ * Display debug mode startup message
+ */
+export function displayDebugStartup(): void {
+  const level = getDebugLevel();
+  if (level > 0) {
+    const tmpDir = os.tmpdir();
+    const errorLogPath = path.join(tmpDir, 'anyclaude-errors.log');
+    process.stderr.write('\n═══════════════════════════════════════\n');
+    process.stderr.write(`ANYCLAUDE DEBUG MODE ENABLED (Level ${level})\n`);
+    process.stderr.write(`Error log: ${errorLogPath}\n`);
+    process.stderr.write(`Debug files: ${tmpDir}/anyclaude-debug-*.json\n`);
+    if (level >= 2) {
+      process.stderr.write('Verbose: Duplicate filtering details enabled\n');
+    }
+    process.stderr.write('═══════════════════════════════════════\n\n');
+  }
+}
+
+/**
+ * Check if debug mode is enabled
+ */
+/**
+ * Get the debug level from ANYCLAUDE_DEBUG environment variable
+ * Returns 0 if not set, 1 for basic debug, 2 for verbose debug
+ * Defaults to 1 if unrecognized string is passed
+ */
+export function getDebugLevel(): number {
+  const debugValue = process.env.ANYCLAUDE_DEBUG;
+  if (!debugValue) return 0;
+  
+  const level = parseInt(debugValue, 10);
+  if (isNaN(level)) return 1; // Default to level 1 for any non-numeric value
+  
+  return Math.max(0, Math.min(2, level)); // Clamp to 0-2 range
+}
+
+export function isDebugEnabled(): boolean {
+  return getDebugLevel() > 0;
+}
+
+/**
+ * Check if verbose debug mode (level 2) is enabled
+ */
+export function isVerboseDebugEnabled(): boolean {
+  return getDebugLevel() >= 2;
+}
+
+/**
+ * Log a debug message at the specified level
+ * @param level - Minimum debug level required to show this message (1 or 2)
+ * @param message - The message to log
+ * @param data - Optional data to append to the message
+ */
+export function debug(level: 1 | 2, message: string, data?: any): void {
+  if (getDebugLevel() >= level) {
+    const prefix = '[ANYCLAUDE DEBUG]';
+    if (data !== undefined) {
+      // For objects/errors, stringify with a length limit
+      const dataStr = typeof data === 'object' ? 
+        JSON.stringify(data).substring(0, 200) : 
+        String(data);
+      console.error(`${prefix} ${message}`, dataStr);
+    } else {
+      console.error(`${prefix} ${message}`);
+    }
+  }
+}

src/json-schema.ts

@@ -67,8 +67,18 @@ export function providerizeSchema(
 
   // Only add required properties for OpenAI
   if (provider === "openai") {
-    result.required = Object.keys(schema.properties);
-    result.additionalProperties = false;
+    // Preserve existing required fields if they exist, otherwise don't mark any as required
+    // This prevents marking optional fields as required which causes OpenAI validation errors
+    if (schema.required && Array.isArray(schema.required)) {
+      result.required = schema.required;
+    }
+    // Only set additionalProperties to false if it's not already defined
+    // This preserves the original schema's intent
+    if (schema.additionalProperties === undefined) {
+      result.additionalProperties = false;
+    } else {
+      result.additionalProperties = schema.additionalProperties;
+    }
   }
 
   return result;

src/main.ts

@@ -10,6 +10,93 @@ import {
   createAnthropicProxy,
   type CreateAnthropicProxyOptions,
 } from "./anthropic-proxy";
+import yargsParser from "yargs-parser";
+
+const FLAGS = {
+  reasoningEffort: {
+    long: "reasoning-effort",
+    short: "e",
+    values: ["minimal", "low", "medium", "high"] as const,
+  },
+  serviceTier: {
+    long: "service-tier",
+    short: "t",
+    values: ["flex", "priority"] as const,
+  },
+} as const;
+
+function parseAnyclaudeFlags(rawArgs: string[]) {
+  const parsed = yargsParser(rawArgs, {
+    configuration: {
+      "unknown-options-as-args": false,
+      "halt-at-non-option": false,
+      "camel-case-expansion": false,
+      "dot-notation": false,
+    },
+  });
+  const reasoningEffort = (parsed[FLAGS.reasoningEffort.long] ??
+    parsed[FLAGS.reasoningEffort.short]) as string | undefined;
+  const serviceTier = (parsed[FLAGS.serviceTier.long] ??
+    parsed[FLAGS.serviceTier.short]) as string | undefined;
+  const specs = Object.values(FLAGS);
+  const filteredArgs: string[] = [];
+  let helpRequested = false;
+  let i = 0;
+  let passthrough = false;
+  while (i < rawArgs.length) {
+    const arg = rawArgs[i]!;
+    if (passthrough) {
+      filteredArgs.push(arg);
+      i++;
+      continue;
+    }
+    if (arg === "--") {
+      passthrough = true;
+      filteredArgs.push(arg);
+      i++;
+      continue;
+    }
+    if (arg === "-h" || arg === "--help") helpRequested = true;
+    let matched = false;
+    for (const spec of specs) {
+      const long = `--${spec.long}`;
+      const short = `-${spec.short}`;
+      if (arg === long || arg === short) {
+        i += 2;
+        matched = true;
+        break;
+      }
+      if (arg.startsWith(long + "=") || arg.startsWith(short + "=")) {
+        i += 1;
+        matched = true;
+        break;
+      }
+    }
+    if (matched) continue;
+    filteredArgs.push(arg);
+    i++;
+  }
+  return { reasoningEffort, serviceTier, filteredArgs, helpRequested };
+}
+
+const rawArgs = process.argv.slice(2);
+const { reasoningEffort, serviceTier, filteredArgs, helpRequested } =
+  parseAnyclaudeFlags(rawArgs);
+
+for (const [key, spec] of Object.entries(FLAGS) as Array<
+  [keyof typeof FLAGS, (typeof FLAGS)[keyof typeof FLAGS]]
+>) {
+  const val = (key === "reasoningEffort" ? reasoningEffort : serviceTier) as
+    | string
+    | undefined;
+  if (val) {
+    const allowed = new Set(spec.values as readonly string[]);
+    if (!allowed.has(val as any)) {
+      console.error(`Invalid ${spec.long}. Use ${spec.values.join("|")}.`);
+      process.exit(1);
+    }
+  }
+}
 
 // providers are supported providers to proxy requests by name.
 // Model names are split when requested by `/`. The provider
@@ -23,7 +110,10 @@ const providers: CreateAnthropicProxyOptions["providers"] = {
         const body = JSON.parse(init.body);
         const maxTokens = body.max_tokens;
         delete body["max_tokens"];
-        body.max_completion_tokens = maxTokens;
+        if (typeof maxTokens !== "undefined")
+          body.max_completion_tokens = maxTokens;
+        if (reasoningEffort) body.reasoning = { effort: reasoningEffort };
+        if (serviceTier) body.service_tier = serviceTier;
         init.body = JSON.stringify(body);
       }
       return globalThis.fetch(url, init);
@@ -56,10 +146,22 @@ const proxyURL = createAnthropicProxy({
   providers,
 });
 
+const params = [
+  `proxy=${proxyURL}`,
+  ...(
+    Object.entries({ reasoningEffort, serviceTier }) as Array<
+      [keyof typeof FLAGS, string | undefined]
+    >
+  ).map(([k, v]) => (v ? `${FLAGS[k].long}=${v}` : undefined)),
+]
+  .filter(Boolean)
+  .join(" ");
+console.log(`[anyclaude] ${params}`);
+
 if (process.env.PROXY_ONLY === "true") {
-  console.log("Proxy only mode: "+proxyURL);
+  console.log("Proxy only mode: " + proxyURL);
 } else {
-  const claudeArgs = process.argv.slice(2);
+  const claudeArgs = filteredArgs;
   const proc = spawn("claude", claudeArgs, {
     env: {
       ...process.env,
@@ -68,12 +170,15 @@ if (process.env.PROXY_ONLY === "true") {
     stdio: "inherit",
   });
   proc.on("exit", (code) => {
-    if (claudeArgs[0] === "-h" || claudeArgs[0] === "--help") {
-      console.log("\nCustom Models:")
-      console.log("  --model <provider>/<model>      e.g. openai/o3");
+    if (helpRequested) {
+      console.log("\nanyclaude flags:");
+      console.log("  --model <provider>/<model>      e.g. openai/gpt-5");
+      for (const spec of Object.values(FLAGS)) {
+        const vals = spec.values.join("|");
+        console.log(`  --${spec.long}, -${spec.short} <${vals}>`);
+      }
     }
 
     process.exit(code);
   });
 }
-