diff --git a/packages/@ant/model-provider/src/index.ts b/packages/@ant/model-provider/src/index.ts
index a4acf428c..6f0ccdbaf 100644
--- a/packages/@ant/model-provider/src/index.ts
+++ b/packages/@ant/model-provider/src/index.ts
@@ -61,3 +61,10 @@ export { anthropicMessagesToOpenAI } from './shared/openaiConvertMessages.js'
 export type { ConvertMessagesOptions } from './shared/openaiConvertMessages.js'
 export { anthropicToolsToOpenAI, anthropicToolChoiceToOpenAI } from './shared/openaiConvertTools.js'
 export { adaptOpenAIStreamToAnthropic } from './shared/openaiStreamAdapter.js'
+
+// Codex provider utilities
+export { normalizeCodexCallId, resolveCodexCallId, createCodexFallbackCallId } from './providers/codex/callIds.js'
+export { resolveCodexModel, resolveCodexMaxTokens } from './providers/codex/modelMapping.js'
+export { anthropicMessagesToCodexInput } from './providers/codex/convertMessages.js'
+export type { CodexImageConversionOptions } from './providers/codex/convertMessages.js'
+export { anthropicToolsToCodex } from './providers/codex/convertTools.js'
diff --git a/src/services/api/codex/callIds.ts b/packages/@ant/model-provider/src/providers/codex/callIds.ts
similarity index 100%
rename from src/services/api/codex/callIds.ts
rename to packages/@ant/model-provider/src/providers/codex/callIds.ts
diff --git a/src/services/api/codex/convertMessages.ts b/packages/@ant/model-provider/src/providers/codex/convertMessages.ts
similarity index 99%
rename from src/services/api/codex/convertMessages.ts
rename to packages/@ant/model-provider/src/providers/codex/convertMessages.ts
index 12e465de8..5bb8b1d31 100644
--- a/src/services/api/codex/convertMessages.ts
+++ b/packages/@ant/model-provider/src/providers/codex/convertMessages.ts
@@ -4,7 +4,7 @@ import type {
   ResponseInputItem,
   ResponseInputText,
 } from 'openai/resources/responses/responses.mjs'
-import type { Message } from '../../../types/message.js'
+import type { Message } from '../../types/index.js'
 import {
   normalizeCodexCallId,
   resolveCodexCallId,
diff --git a/src/services/api/codex/convertTools.ts b/packages/@ant/model-provider/src/providers/codex/convertTools.ts
similarity index 100%
rename from src/services/api/codex/convertTools.ts
rename to packages/@ant/model-provider/src/providers/codex/convertTools.ts
diff --git a/src/services/api/codex/model.ts b/packages/@ant/model-provider/src/providers/codex/modelMapping.ts
similarity index 100%
rename from src/services/api/codex/model.ts
rename to packages/@ant/model-provider/src/providers/codex/modelMapping.ts
diff --git a/src/services/api/codex/__tests__/conversion.test.ts b/src/services/api/codex/__tests__/conversion.test.ts
index 6e5f8aaf8..6ab211ad3 100644
--- a/src/services/api/codex/__tests__/conversion.test.ts
+++ b/src/services/api/codex/__tests__/conversion.test.ts
@@ -1,7 +1,6 @@
 import { describe, expect, test } from 'bun:test'
 import { createAssistantMessage, createUserMessage } from '../../../../utils/messages.js'
-import { anthropicMessagesToCodexInput } from '../convertMessages.js'
-import { anthropicToolsToCodex } from '../convertTools.js'
+import { anthropicMessagesToCodexInput, anthropicToolsToCodex } from '@ant/model-provider'
 
 describe('anthropicMessagesToCodexInput', () => {
   test('replays assistant tool calls and user tool results in order', async () => {
diff --git a/src/services/api/codex/__tests__/streaming.test.ts b/src/services/api/codex/__tests__/streaming.test.ts
index 70e4eb716..600cb6c1a 100644
--- a/src/services/api/codex/__tests__/streaming.test.ts
+++ b/src/services/api/codex/__tests__/streaming.test.ts
@@ -97,33 +97,68 @@ mock.module('../client.js', () => ({
   }),
 }))
 
-mock.module('../convertMessages.js', () => ({
-  anthropicMessagesToCodexInput: () => [],
-}))
-
-mock.module('../convertTools.js', () => ({
-  anthropicToolsToCodex: () => [],
-}))
-
-mock.module('../model.js', () => ({
-  resolveCodexModel: () => 'gpt-5.4',
-  resolveCodexMaxTokens: () => 4096,
-}))
+// Mock only model resolution — conversion functions can use real implementations
+// since the client mock controls API responses.
+mock.module('@ant/model-provider', () => {
+  // Import the real module to preserve conversion functions
+  const real = require('@ant/model-provider')
+  return {
+    ...real,
+    resolveCodexModel: () => 'gpt-5.4',
+    resolveCodexMaxTokens: () => 4096,
+  }
+})
 
 mock.module('../../../../utils/context.js', () => ({
+  MODEL_CONTEXT_WINDOW_DEFAULT: 200_000,
+  COMPACT_MAX_OUTPUT_TOKENS: 20_000,
+  CAPPED_DEFAULT_MAX_TOKENS: 8_000,
+  ESCALATED_MAX_TOKENS: 64_000,
+  is1mContextDisabled: () => false,
+  has1mContext: () => false,
+  modelSupports1M: () => false,
+  getContextWindowForModel: () => 200_000,
+  getSonnet1mExpTreatmentEnabled: () => false,
+  calculateContextPercentages: () => ({}),
   getModelMaxOutputTokens: () => ({ upperLimit: 4096 }),
+  getMaxThinkingTokensForModel: () => 0,
 }))
 
 mock.module('../../../../utils/api.js', () => ({
   toolToAPISchema: async () => ({}),
+  appendSystemContext: () => {},
+  prependUserContext: () => {},
+  logAPIPrefix: () => {},
+  splitSysPromptPrefix: () => ({ prefix: '', rest: [] }),
+  logContextMetrics: async () => {},
+  normalizeToolInput: (input: any) => input,
+  normalizeToolInputForAPI: (input: any) => input,
 }))
 
-mock.module('../../../../utils/debug.js', () => ({
+mock.module('src/utils/debug.ts', () => ({
+  getMinDebugLogLevel: () => 'debug' as const,
+  isDebugMode: () => false,
+  enableDebugLogging: () => false,
+  getDebugFilter: () => null,
+  isDebugToStdErr: () => false,
+  getDebugFilePath: () => null as string | null,
+  setHasFormattedOutput: () => {},
+  getHasFormattedOutput: () => false,
+  flushDebugLogs: async () => {},
   logForDebugging: () => {},
+  getDebugLogPath: () => '/tmp/mock-debug.log',
+  logAntError: () => {},
 }))
 
 mock.module('../../../../services/langfuse/tracing.js', () => ({
+  createTrace: () => null,
   recordLLMObservation: () => {},
+  recordToolObservation: () => {},
+  createToolBatchSpan: () => null,
+  endToolBatchSpan: () => {},
+  createSubagentTrace: () => null,
+  createChildSpan: () => null,
+  endTrace: () => {},
 }))
 
 mock.module('../../../../services/langfuse/convert.js', () => ({
diff --git a/src/services/api/codex/index.ts b/src/services/api/codex/index.ts
index eb6e010bf..0bfaabc9d 100644
--- a/src/services/api/codex/index.ts
+++ b/src/services/api/codex/index.ts
@@ -27,15 +27,18 @@ import {
   convertOutputToLangfuse,
   convertToolsToLangfuse,
 } from '../../../services/langfuse/convert.js'
-import { anthropicMessagesToCodexInput } from './convertMessages.js'
-import { anthropicToolsToCodex } from './convertTools.js'
+import {
+  anthropicMessagesToCodexInput,
+  anthropicToolsToCodex,
+  resolveCodexMaxTokens,
+  resolveCodexModel,
+} from '@ant/model-provider'
 import { getCodexClient } from './client.js'
 import { uploadCodexBase64Image } from './imageUpload.js'
 import {
   getCodexConfigurationError,
   normalizeCodexError,
 } from './errors.js'
-import { resolveCodexMaxTokens, resolveCodexModel } from './model.js'
 import { sanitizeCodexRequest } from './preflight.js'
 import {
   addCodexUsage,
diff --git a/src/services/api/codex/preflight.ts b/src/services/api/codex/preflight.ts
index 5f9856458..2c6ec9b8b 100644
--- a/src/services/api/codex/preflight.ts
+++ b/src/services/api/codex/preflight.ts
@@ -4,7 +4,7 @@ import type {
   ResponseInputItem,
   Tool,
 } from 'openai/resources/responses/responses.mjs'
-import { normalizeCodexCallId } from './callIds.js'
+import { normalizeCodexCallId } from '@ant/model-provider'
 
 function isRecord(value: unknown): value is Record<string, unknown> {
   return typeof value === 'object' && value !== null && !Array.isArray(value)
diff --git a/src/services/api/codex/streaming.ts b/src/services/api/codex/streaming.ts
index dad8ef156..f8a27c0c6 100644
--- a/src/services/api/codex/streaming.ts
+++ b/src/services/api/codex/streaming.ts
@@ -14,7 +14,7 @@ import {
   normalizeContentFromAPI,
 } from '../../../utils/messages.js'
 import { getCodexClient } from './client.js'
-import { resolveCodexCallId } from './callIds.js'
+import { resolveCodexCallId } from '@ant/model-provider'
 import { toStreamingCodexRequest } from './preflight.js'
 
 export type RawAssistantBlock =