feat: add dynamic x-api-provider and reasoning_effort support

- Add per-model provider configuration in config.json
- Implement getModelProvider() to fetch provider from model config
- Update all header generators to accept dynamic provider parameter
- Add reasoning_effort field handling for common endpoint type
- Support auto/low/medium/high/off reasoning levels for common models

This enables flexible multi-provider support and reasoning control
across different endpoint types (anthropic, openai, common).

transformers/request-anthropic.js

@@ -154,7 +154,7 @@ export function transformToAnthropic(openaiRequest) {
   return anthropicRequest;
 }
 
-export function getAnthropicHeaders(authHeader, clientHeaders = {}, isStreaming = true, modelId = null) {
+export function getAnthropicHeaders(authHeader, clientHeaders = {}, isStreaming = true, modelId = null, provider = 'anthropic') {
   // Generate unique IDs if not provided
   const sessionId = clientHeaders['x-session-id'] || generateUUID();
   const messageId = clientHeaders['x-assistant-message-id'] || generateUUID();
@@ -165,7 +165,7 @@ export function getAnthropicHeaders(authHeader, clientHeaders = {}, isStreaming
     'anthropic-version': clientHeaders['anthropic-version'] || '2023-06-01',
     'authorization': authHeader || '',
     'x-api-key': 'placeholder',
-    'x-api-provider': 'anthropic',
+    'x-api-provider': provider,
     'x-factory-client': 'cli',
     'x-session-id': sessionId,
     'x-assistant-message-id': messageId,

transformers/request-common.js

@@ -1,5 +1,5 @@
 import { logDebug } from '../logger.js';
-import { getSystemPrompt, getUserAgent } from '../config.js';
+import { getSystemPrompt, getUserAgent, getModelReasoning } from '../config.js';
 
 export function transformToCommon(openaiRequest) {
   logDebug('Transforming OpenAI request to Common format');
@@ -39,11 +39,25 @@ export function transformToCommon(openaiRequest) {
     }
   }
 
+  // Handle reasoning_effort field based on model configuration
+  const reasoningLevel = getModelReasoning(openaiRequest.model);
+  if (reasoningLevel === 'auto') {
+    // Auto mode: preserve original request's reasoning_effort field exactly as-is
+    // If original request has reasoning_effort field, keep it; otherwise don't add one
+  } else if (reasoningLevel && ['low', 'medium', 'high'].includes(reasoningLevel)) {
+    // Specific level: override with model configuration
+    commonRequest.reasoning_effort = reasoningLevel;
+  } else {
+    // Off or invalid: explicitly remove reasoning_effort field
+    // This ensures any reasoning_effort field from the original request is deleted
+    delete commonRequest.reasoning_effort;
+  }
+
   logDebug('Transformed Common request', commonRequest);
   return commonRequest;
 }
 
-export function getCommonHeaders(authHeader, clientHeaders = {}) {
+export function getCommonHeaders(authHeader, clientHeaders = {}, provider = 'baseten') {
   // Generate unique IDs if not provided
   const sessionId = clientHeaders['x-session-id'] || generateUUID();
   const messageId = clientHeaders['x-assistant-message-id'] || generateUUID();
@@ -52,7 +66,7 @@ export function getCommonHeaders(authHeader, clientHeaders = {}) {
     'accept': 'application/json',
     'content-type': 'application/json',
     'authorization': authHeader || '',
-    'x-api-provider': 'baseten',
+    'x-api-provider': provider,
     'x-factory-client': 'cli',
     'x-session-id': sessionId,
     'x-assistant-message-id': messageId,

transformers/request-openai.js

@@ -133,7 +133,7 @@ export function transformToOpenAI(openaiRequest) {
   return targetRequest;
 }
 
-export function getOpenAIHeaders(authHeader, clientHeaders = {}) {
+export function getOpenAIHeaders(authHeader, clientHeaders = {}, provider = 'openai') {
   // Generate unique IDs if not provided
   const sessionId = clientHeaders['x-session-id'] || generateUUID();
   const messageId = clientHeaders['x-assistant-message-id'] || generateUUID();
@@ -141,7 +141,7 @@ export function getOpenAIHeaders(authHeader, clientHeaders = {}) {
   const headers = {
     'content-type': 'application/json',
     'authorization': authHeader || '',
-    'x-api-provider': 'openai',
+    'x-api-provider': provider,
     'x-factory-client': 'cli',
     'x-session-id': sessionId,
     'x-assistant-message-id': messageId,