diff --git a/packages/core/package.json b/packages/core/package.json
index 970b01e4d4..9dc4a7b2d7 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -22,7 +22,7 @@
     "./state/*": "./src/state/*.ts"
   },
   "scripts": {
-    "test": "bun test src/handlers/command-handler.test.ts && bun test src/handlers/clone.test.ts && bun test src/db/adapters/postgres.test.ts && bun test src/db/adapters/sqlite.test.ts src/db/codebases.test.ts src/db/connection.test.ts src/db/conversations.test.ts src/db/env-vars.test.ts src/db/isolation-environments.test.ts src/db/messages.test.ts src/db/sessions.test.ts src/db/workflow-events.test.ts src/db/workflows.test.ts src/utils/defaults-copy.test.ts src/utils/worktree-sync.test.ts src/utils/conversation-lock.test.ts src/utils/credential-sanitizer.test.ts src/utils/port-allocation.test.ts src/utils/error.test.ts src/utils/error-formatter.test.ts src/utils/github-graphql.test.ts src/config/ src/state/ && bun test src/utils/path-validation.test.ts && bun test src/services/cleanup-service.test.ts && bun test src/services/title-generator.test.ts && bun test src/workflows/ && bun test src/operations/workflow-operations.test.ts && bun test src/operations/isolation-operations.test.ts && bun test src/orchestrator/orchestrator.test.ts && bun test src/orchestrator/orchestrator-agent.test.ts && bun test src/orchestrator/orchestrator-isolation.test.ts",
+    "test": "bun test src/handlers/command-handler.test.ts && bun test src/handlers/clone.test.ts && bun test src/db/adapters/postgres.test.ts && bun test src/db/adapters/sqlite.test.ts src/db/codebases.test.ts src/db/connection.test.ts src/db/env-vars.test.ts src/db/isolation-environments.test.ts src/db/messages.test.ts src/db/sessions.test.ts src/db/workflow-events.test.ts src/db/workflows.test.ts src/utils/defaults-copy.test.ts src/utils/worktree-sync.test.ts src/utils/conversation-lock.test.ts src/utils/credential-sanitizer.test.ts src/utils/port-allocation.test.ts src/utils/error.test.ts src/utils/error-formatter.test.ts src/utils/github-graphql.test.ts src/config/ src/state/ && bun test src/db/conversations.test.ts && bun test src/utils/path-validation.test.ts && bun test src/services/cleanup-service.test.ts && bun test src/services/title-generator.test.ts && bun test src/workflows/ && bun test src/operations/workflow-operations.test.ts && bun test src/operations/isolation-operations.test.ts && bun test src/orchestrator/orchestrator.test.ts && bun test src/orchestrator/orchestrator-agent.test.ts && bun test src/orchestrator/orchestrator-isolation.test.ts",
     "type-check": "bun x tsc --noEmit",
     "build": "echo 'No build needed - Bun runs TypeScript directly'"
   },
diff --git a/packages/core/src/db/conversations.test.ts b/packages/core/src/db/conversations.test.ts
index e63ae767c5..befbd3b489 100644
--- a/packages/core/src/db/conversations.test.ts
+++ b/packages/core/src/db/conversations.test.ts
@@ -11,6 +11,23 @@ mock.module('./connection', () => ({
   getDialect: () => mockPostgresDialect,
 }));
 
+// Module-level variable to control mock config assistant per test
+let mockConfigAssistant = 'claude';
+
+// Mock config-loader to control assistant type in tests without filesystem dependency
+mock.module('../config/config-loader', () => ({
+  loadConfig: async () => ({
+    assistant: mockConfigAssistant,
+    assistants: { claude: {}, codex: {} },
+    botName: 'Archon',
+    streaming: { telegram: 'stream', discord: 'batch', slack: 'batch' },
+    paths: { workspaces: '/tmp', worktrees: '/tmp' },
+    concurrency: { maxConversations: 10 },
+    commands: { folder: undefined, autoLoad: true },
+    defaults: { copyDefaults: true, loadDefaultCommands: true, loadDefaultWorkflows: true },
+  }),
+}));
+
 import {
   getOrCreateConversation,
   updateConversation,
@@ -31,6 +48,8 @@ describe('conversations', () => {
       // Save and clear env var to ensure test isolation
       originalDefaultAiAssistant = process.env.DEFAULT_AI_ASSISTANT;
       delete process.env.DEFAULT_AI_ASSISTANT;
+      // Reset mock config to default
+      mockConfigAssistant = 'claude';
     });
 
     afterEach(() => {
@@ -40,6 +59,7 @@ describe('conversations', () => {
       } else {
         process.env.DEFAULT_AI_ASSISTANT = originalDefaultAiAssistant;
       }
+      // No need to reset mockConfigAssistant here — beforeEach resets it to 'claude' before each test
     });
 
     const existingConversation: Conversation = {
@@ -122,8 +142,10 @@ describe('conversations', () => {
     });
 
     test('uses DEFAULT_AI_ASSISTANT env var when set', async () => {
-      // Set env var for this test (afterEach will restore original)
+      // The mock returns mockConfigAssistant directly (env var contract tested in config-loader.test.ts).
+      // Set both so the test documents that loadConfig() honours DEFAULT_AI_ASSISTANT.
       process.env.DEFAULT_AI_ASSISTANT = 'codex';
+      mockConfigAssistant = 'codex';
 
       const newConversation: Conversation = {
         ...existingConversation,
@@ -144,7 +166,30 @@ describe('conversations', () => {
       );
     });
 
-    test('falls back to claude when codebase not found', async () => {
+    test('uses saved global config defaultAssistant when no env var', async () => {
+      // Simulate global config having defaultAssistant=codex (set via Settings page)
+      mockConfigAssistant = 'codex';
+
+      const newConversation: Conversation = {
+        ...existingConversation,
+        id: 'conv-new',
+        ai_assistant_type: 'codex',
+      };
+
+      mockQuery.mockResolvedValueOnce(createQueryResult([]));
+      mockQuery.mockResolvedValueOnce(createQueryResult([newConversation]));
+
+      const result = await getOrCreateConversation('telegram', 'chat-new');
+
+      expect(result).toEqual(newConversation);
+      expect(mockQuery).toHaveBeenNthCalledWith(
+        2,
+        'INSERT INTO remote_agent_conversations (platform_type, platform_conversation_id, ai_assistant_type, codebase_id, cwd) VALUES ($1, $2, $3, $4, $5) RETURNING *',
+        ['telegram', 'chat-new', 'codex', null, null]
+      );
+    });
+
+    test('uses config default assistant when codebase not found', async () => {
       const newConversation: Conversation = {
         ...existingConversation,
         id: 'conv-new',
diff --git a/packages/core/src/db/conversations.ts b/packages/core/src/db/conversations.ts
index 0a7a237da3..37ed4037ed 100644
--- a/packages/core/src/db/conversations.ts
+++ b/packages/core/src/db/conversations.ts
@@ -5,6 +5,7 @@ import { pool, getDialect } from './connection';
 import type { Conversation } from '../types';
 import { ConversationNotFoundError } from '../types';
 import { createLogger } from '@archon/paths';
+import { loadConfig } from '../config/config-loader';
 
 /** Lazy-initialized logger (deferred so test mocks can intercept createLogger) */
 let cachedLog: ReturnType<typeof createLogger> | undefined;
@@ -72,7 +73,8 @@ export async function getOrCreateConversation(
   // Check if we should inherit from a parent conversation (e.g., Discord thread inheriting from parent channel)
   let inheritedCodebaseId: string | null = null;
   let inheritedCwd: string | null = null;
-  let assistantType = process.env.DEFAULT_AI_ASSISTANT ?? 'claude';
+  const config = await loadConfig();
+  let assistantType = config.assistant;
 
   if (parentConversationId) {
     const parent = await pool.query<Conversation>(