diff --git a/apps/frontend/src/main/agent/agent-process.ts b/apps/frontend/src/main/agent/agent-process.ts
index 58f9731674..2acac57b43 100644
--- a/apps/frontend/src/main/agent/agent-process.ts
+++ b/apps/frontend/src/main/agent/agent-process.ts
@@ -206,6 +206,17 @@ export class AgentProcessManager {
     // are available even when app is launched from Finder/Dock
     const augmentedEnv = getAugmentedEnv();
 
+    // Debug: Log OAuth token sources (when DEBUG=true or in development mode)
+    const DEBUG = process.env.DEBUG === 'true' || process.env.NODE_ENV === 'development';
+    if (DEBUG) {
+      const maskToken = (t: string | undefined) => t ? `${t.substring(0, 15)}...` : 'none';
+      console.log('[AgentProcess] Token sources:', {
+        processEnv: maskToken(process.env.CLAUDE_CODE_OAUTH_TOKEN),
+        extraEnv: maskToken(extraEnv.CLAUDE_CODE_OAUTH_TOKEN),
+        profileEnv: maskToken(profileEnv.CLAUDE_CODE_OAUTH_TOKEN),
+      });
+    }
+
     // On Windows, detect and pass git-bash path for Claude Code CLI
     // Electron can detect git via where.exe, but Python subprocess may not have the same PATH
     const gitBashEnv: Record<string, string> = {};
@@ -229,9 +240,13 @@ export class AgentProcessManager {
     const ghCliEnv = this.detectAndSetCliPath('gh');
     const glabCliEnv = this.detectAndSetCliPath('glab');
 
+<<<<<<< HEAD
     // Profile env is spread last to ensure CLAUDE_CONFIG_DIR and auth vars
     // from the active profile always win over extraEnv or augmentedEnv.
     const mergedEnv = {
+=======
+    const finalEnv = {
+>>>>>>> refs/remotes/upstream/pr/1326
       ...augmentedEnv,
       ...gitBashEnv,
       ...claudeCliEnv,
@@ -244,6 +259,7 @@ export class AgentProcessManager {
       PYTHONUTF8: '1'
     } as NodeJS.ProcessEnv;
 
+<<<<<<< HEAD
     // When the active profile provides CLAUDE_CONFIG_DIR, clear CLAUDE_CODE_OAUTH_TOKEN
     // from the spawn environment. CLAUDE_CONFIG_DIR lets Claude Code resolve its own
     // OAuth tokens from the config directory, making an explicit token unnecessary.
@@ -266,6 +282,15 @@ export class AgentProcessManager {
     });
 
     return mergedEnv;
+=======
+    // Debug: Log final token being passed (only when DEBUG=true)
+    if (DEBUG) {
+      const maskToken = (t: string | undefined) => t ? `${t.substring(0, 15)}...` : 'none';
+      console.log('[AgentProcess] Final CLAUDE_CODE_OAUTH_TOKEN:', maskToken(finalEnv.CLAUDE_CODE_OAUTH_TOKEN));
+    }
+
+    return finalEnv;
+>>>>>>> refs/remotes/upstream/pr/1326
   }
 
   private handleProcessFailure(
diff --git a/apps/frontend/src/main/claude-profile-manager.ts b/apps/frontend/src/main/claude-profile-manager.ts
index e91117e8cb..01415a6b00 100644
--- a/apps/frontend/src/main/claude-profile-manager.ts
+++ b/apps/frontend/src/main/claude-profile-manager.ts
@@ -53,8 +53,13 @@ import {
   createProfileDirectory as createProfileDirectoryImpl,
   isProfileAuthenticated as isProfileAuthenticatedImpl,
   hasValidToken,
+<<<<<<< HEAD
   expandHomePath,
   getEmailFromConfigDir
+=======
+  isValidTokenFormat,
+  expandHomePath
+>>>>>>> refs/remotes/upstream/pr/1326
 } from './claude-profile/profile-utils';
 import { debugLog } from '../shared/utils/debug-logger';
 
@@ -490,6 +495,7 @@ export class ClaudeProfileManager {
   /**
    * Set the OAuth token for a profile (encrypted storage).
    * Used when capturing token from `claude setup-token` output.
+   * Returns false if token format is invalid or profile not found.
    */
   setProfileToken(profileId: string, token: string, email?: string): boolean {
     const profile = this.getProfile(profileId);
@@ -497,6 +503,12 @@ export class ClaudeProfileManager {
       return false;
     }
 
+    // Validate token format before storing
+    if (!isValidTokenFormat(token)) {
+      console.error('[ProfileManager] Invalid token format. Token must start with sk-ant-oat01-');
+      return false;
+    }
+
     // Encrypt the token before storing
     profile.oauthToken = encryptToken(token);
     profile.tokenCreatedAt = new Date();
@@ -542,6 +554,7 @@ export class ClaudeProfileManager {
     const profile = this.getActiveProfile();
     const env: Record<string, string> = {};
 
+<<<<<<< HEAD
     // All profiles now use explicit CLAUDE_CONFIG_DIR for isolation
     // This prevents interference with external Claude Code CLI usage
     if (profile?.configDir) {
@@ -577,6 +590,24 @@ export class ClaudeProfileManager {
           credentials.error ? `(error: ${credentials.error})` : ''
         );
       }
+=======
+    if (profile?.oauthToken) {
+      // Decrypt the token before putting in environment
+      const decryptedToken = decryptToken(profile.oauthToken);
+      if (decryptedToken) {
+        // Validate token format after decryption
+        if (isValidTokenFormat(decryptedToken)) {
+          env.CLAUDE_CODE_OAUTH_TOKEN = decryptedToken;
+        } else {
+          console.warn('[ProfileManager] Decrypted token has invalid format, falling back to configDir');
+        }
+      }
+    }
+
+    // Fallback to configDir for backward compatibility (if no valid token and not default profile)
+    if (!env.CLAUDE_CODE_OAUTH_TOKEN && profile?.configDir && !profile.isDefault) {
+      env.CLAUDE_CONFIG_DIR = profile.configDir;
+>>>>>>> refs/remotes/upstream/pr/1326
     }
 
     return env;
diff --git a/apps/frontend/src/main/claude-profile/profile-utils.ts b/apps/frontend/src/main/claude-profile/profile-utils.ts
index c6799a6e0c..f0e97b2600 100644
--- a/apps/frontend/src/main/claude-profile/profile-utils.ts
+++ b/apps/frontend/src/main/claude-profile/profile-utils.ts
@@ -9,6 +9,20 @@ import { existsSync, readFileSync, readdirSync, mkdirSync } from 'fs';
 import type { ClaudeProfile, APIProfile } from '../../shared/types';
 import { getCredentialsFromKeychain } from './credential-utils';
 
+/**
+ * OAuth token format pattern (sk-ant-oat01-...)
+ * This is the expected format for Claude Code OAuth tokens.
+ */
+const OAUTH_TOKEN_PATTERN = /^sk-ant-oat01-[A-Za-z0-9_-]+$/;
+
+/**
+ * Validate OAuth token format.
+ * Returns true if token matches expected format (sk-ant-oat01-...).
+ */
+export function isValidTokenFormat(token: string | undefined): boolean {
+  return !!token && OAUTH_TOKEN_PATTERN.test(token);
+}
+
 /**
  * Default Claude config directory
  */
@@ -176,6 +190,7 @@ export function isProfileAuthenticated(profile: ClaudeProfile): boolean {
 }
 
 /**
+<<<<<<< HEAD
  * Check if a profile has a valid OAuth token stored in the profile.
  *
  * DEPRECATED: This function checks for CACHED OAuth tokens which we no longer store.
@@ -190,12 +205,17 @@ export function isProfileAuthenticated(profile: ClaudeProfile): boolean {
  * Use isProfileAuthenticated() to check for configDir-based credentials instead.
  *
  * See: docs/LONG_LIVED_AUTH_PLAN.md for full context.
+=======
+ * Check if a profile has a valid OAuth token.
+ * Token is valid for 1 year from creation and must match expected format.
+>>>>>>> refs/remotes/upstream/pr/1326
  */
 export function hasValidToken(profile: ClaudeProfile): boolean {
   if (!profile?.oauthToken) {
     return false;
   }
 
+<<<<<<< HEAD
   // For legacy profiles with stored oauthToken, return true.
   // The actual token validity is determined by the Keychain (via CLAUDE_CONFIG_DIR).
   // We keep this for backwards compat to avoid breaking existing profiles during migration.
@@ -214,6 +234,23 @@ export function isAPIProfileAuthenticated(profile: APIProfile): boolean {
   // Check for presence of required fields
   if (!profile?.apiKey || !profile?.baseUrl) {
     return false;
+=======
+  // Validate token format (must start with sk-ant-oat01-)
+  // Note: For encrypted tokens (enc:...), we can't validate format before decryption,
+  // but the token-encryption module will return undefined if decryption fails
+  if (!profile.oauthToken.startsWith('enc:') && !isValidTokenFormat(profile.oauthToken)) {
+    console.warn('[profile-utils] Token has invalid format (expected sk-ant-oat01-...)');
+    return false;
+  }
+
+  // Check if token is expired (1 year validity)
+  if (profile.tokenCreatedAt) {
+    const oneYearAgo = new Date();
+    oneYearAgo.setFullYear(oneYearAgo.getFullYear() - 1);
+    if (new Date(profile.tokenCreatedAt) < oneYearAgo) {
+      return false;
+    }
+>>>>>>> refs/remotes/upstream/pr/1326
   }
 
   // Validate that the fields are non-empty strings (after trimming whitespace)
diff --git a/apps/frontend/src/main/claude-profile/token-encryption.ts b/apps/frontend/src/main/claude-profile/token-encryption.ts
index ad8ab2f142..cfc7516d67 100644
--- a/apps/frontend/src/main/claude-profile/token-encryption.ts
+++ b/apps/frontend/src/main/claude-profile/token-encryption.ts
@@ -24,8 +24,9 @@ export function encryptToken(token: string): string {
 
 /**
  * Decrypt a token. Handles both encrypted (enc:...) and legacy plain tokens.
+ * Returns undefined if decryption fails, allowing callers to handle the failure appropriately.
  */
-export function decryptToken(storedToken: string): string {
+export function decryptToken(storedToken: string): string | undefined {
   try {
     if (storedToken.startsWith('enc:') && safeStorage.isEncryptionAvailable()) {
       const encryptedData = Buffer.from(storedToken.slice(4), 'base64');
@@ -33,7 +34,7 @@ export function decryptToken(storedToken: string): string {
     }
   } catch (error) {
     console.error('[TokenEncryption] Failed to decrypt token:', error);
-    return ''; // Return empty string on decryption failure
+    return undefined; // Return undefined on decryption failure
   }
   // Return as-is for legacy unencrypted tokens
   return storedToken;
diff --git a/apps/frontend/src/main/rate-limit-detector.ts b/apps/frontend/src/main/rate-limit-detector.ts
index f5d3f47f14..e8298a6e8e 100644
--- a/apps/frontend/src/main/rate-limit-detector.ts
+++ b/apps/frontend/src/main/rate-limit-detector.ts
@@ -4,8 +4,12 @@
  */
 
 import { getClaudeProfileManager } from './claude-profile-manager';
+<<<<<<< HEAD
 import { getUsageMonitor } from './claude-profile/usage-monitor';
 import { debugLog } from '../shared/utils/debug-logger';
+=======
+import { isValidTokenFormat } from './claude-profile/profile-utils';
+>>>>>>> refs/remotes/upstream/pr/1326
 
 /**
  * Regex pattern to detect Claude Code rate limit messages
@@ -388,6 +392,7 @@ export function detectBillingFailure(
       const effectiveProfileId = profileId || profileManager.getActiveProfile().id;
       const failureType = classifyBillingFailureType(output);
 
+<<<<<<< HEAD
       return {
         isBillingFailure: true,
         profileId: effectiveProfileId,
@@ -395,6 +400,22 @@ export function detectBillingFailure(
         message: getBillingFailureMessage(failureType),
         originalError: sanitizeErrorOutput(output)
       };
+=======
+    if (decryptedToken) {
+      // Validate token format after decryption
+      if (!isValidTokenFormat(decryptedToken)) {
+        console.warn('[getProfileEnv] Token has invalid format for profile:', profile.name);
+        console.warn('[getProfileEnv] Token should start with sk-ant-oat01-. Please re-authenticate.');
+        // Don't use invalid token - fall through to other auth methods
+      } else {
+        console.warn('[getProfileEnv] Using OAuth token for profile:', profile.name);
+        return {
+          CLAUDE_CODE_OAUTH_TOKEN: decryptedToken
+        };
+      }
+    } else {
+      console.warn('[getProfileEnv] Failed to decrypt token for profile:', profile.name);
+>>>>>>> refs/remotes/upstream/pr/1326
     }
   }
 
diff --git a/apps/frontend/src/main/title-generator.ts b/apps/frontend/src/main/title-generator.ts
index 1f19a8109d..bc9fd4c35d 100644
--- a/apps/frontend/src/main/title-generator.ts
+++ b/apps/frontend/src/main/title-generator.ts
@@ -151,6 +151,7 @@ export class TitleGenerator extends EventEmitter {
     debug('Generating title for description:', description.substring(0, 100) + '...');
 
     const autoBuildEnv = this.loadAutoBuildEnv();
+<<<<<<< HEAD
     debug('Environment loaded', {
       hasOAuthToken: !!autoBuildEnv.CLAUDE_CODE_OAUTH_TOKEN
     });
@@ -212,6 +213,17 @@ export class TitleGenerator extends EventEmitter {
       });
       return null;
     }
+=======
+    const profileEnv = getProfileEnv();
+>>>>>>> refs/remotes/upstream/pr/1326
+
+    // Log token sources for debugging (masked for security)
+    const maskToken = (t: string | undefined) => t ? `${t.substring(0, 15)}...` : 'none';
+    debug('Token sources:', {
+      autoBuildEnv: maskToken(autoBuildEnv.CLAUDE_CODE_OAUTH_TOKEN),
+      profileEnv: maskToken(profileEnv.CLAUDE_CODE_OAUTH_TOKEN),
+      effectiveSource: profileEnv.CLAUDE_CODE_OAUTH_TOKEN ? 'profile' : (autoBuildEnv.CLAUDE_CODE_OAUTH_TOKEN ? 'autoBuildEnv' : 'none')
+    });
 
     return new Promise((resolve) => {
       // Parse Python command to handle space-separated commands like "py -3"