fix(cliproxy): address all review feedback (Low + informational)

- Add sync constraint comment on process.exit handler (executor)
- Add TOCTOU race acceptability comment (account-safety)
- Mask email in handleQuotaExhaustion reason string
- Use realistic exhaustion_threshold (5) in test configs

src/cliproxy/account-safety.ts

@@ -273,7 +273,8 @@ export function enforceProviderIsolation(provider: CLIProxyProvider): number {
     pauseAccount(p, accountId);
   }
 
-  // Record for crash recovery (re-read to reduce concurrent write race window)
+  // Record for crash recovery (re-read to reduce concurrent write race window).
+  // TOCTOU race is acceptable for a single-user CLI tool — self-heals on next launch.
   const freshData = loadAutoPaused();
   freshData.sessions = freshData.sessions.filter((s) => s.initiator !== provider);
   freshData.sessions.push({
@@ -457,7 +458,7 @@ export async function handleQuotaExhaustion(
     writeQuotaExhausted(accountId, alternative.id, cooldownMinutes);
     return {
       switchedTo: alternative.id,
-      reason: `Quota exhausted, switched to ${alternative.id}`,
+      reason: `Quota exhausted, switched to ${maskEmail(alternative.id)}`,
     };
   }
 

src/cliproxy/executor/index.ts

@@ -521,6 +521,7 @@ export async function execClaudeWithCLIProxy(
       // No enforcement — still warn about duplicates for awareness
       warnCrossProviderDuplicates(provider);
     } else {
+      // 'exit' handlers must be synchronous — restoreAutoPausedAccounts uses sync fs APIs
       process.on('exit', () => {
         restoreAutoPausedAccounts(provider);
       });

tests/unit/cliproxy/account-safety-quota-exhaustion.test.ts

@@ -173,7 +173,7 @@ describe('Quota Exhaustion Handlers', () => {
           normal_interval_seconds: 300,
           critical_interval_seconds: 60,
           warn_threshold: 20,
-          exhaustion_threshold: 0,
+          exhaustion_threshold: 5,
           cooldown_minutes: 10,
         },
       });
@@ -214,7 +214,7 @@ describe('Quota Exhaustion Handlers', () => {
           normal_interval_seconds: 300,
           critical_interval_seconds: 60,
           warn_threshold: 20,
-          exhaustion_threshold: 0,
+          exhaustion_threshold: 5,
           cooldown_minutes: 10,
         },
       });
@@ -252,7 +252,7 @@ describe('Quota Exhaustion Handlers', () => {
           normal_interval_seconds: 300,
           critical_interval_seconds: 60,
           warn_threshold: 20,
-          exhaustion_threshold: 0,
+          exhaustion_threshold: 5,
           cooldown_minutes: 10,
         },
       });
@@ -299,7 +299,7 @@ describe('Quota Exhaustion Handlers', () => {
           normal_interval_seconds: 300,
           critical_interval_seconds: 60,
           warn_threshold: 20,
-          exhaustion_threshold: 0,
+          exhaustion_threshold: 5,
           cooldown_minutes: 5,
         },
       });

tests/unit/cliproxy/quota-monitor-runtime.test.ts

@@ -59,7 +59,7 @@ describe('Runtime Quota Monitor', () => {
               normal_interval_seconds: 300,
               critical_interval_seconds: 60,
               warn_threshold: 20,
-              exhaustion_threshold: 0,
+              exhaustion_threshold: 5,
               cooldown_minutes: 5,
             },
           },
@@ -92,7 +92,7 @@ describe('Runtime Quota Monitor', () => {
               normal_interval_seconds: 300,
               critical_interval_seconds: 60,
               warn_threshold: 20,
-              exhaustion_threshold: 0,
+              exhaustion_threshold: 5,
               cooldown_minutes: 5,
             },
           },
@@ -118,7 +118,7 @@ describe('Runtime Quota Monitor', () => {
               normal_interval_seconds: 300,
               critical_interval_seconds: 60,
               warn_threshold: 20,
-              exhaustion_threshold: 0,
+              exhaustion_threshold: 5,
               cooldown_minutes: 5,
             },
           },
@@ -161,7 +161,7 @@ describe('Runtime Quota Monitor', () => {
               normal_interval_seconds: 300,
               critical_interval_seconds: 60,
               warn_threshold: 20,
-              exhaustion_threshold: 0,
+              exhaustion_threshold: 5,
               cooldown_minutes: 5,
             },
           },