diff --git a/src/services/infrastructure/ProcessManager.ts b/src/services/infrastructure/ProcessManager.ts
index 8b1a4698..909ab224 100644
--- a/src/services/infrastructure/ProcessManager.ts
+++ b/src/services/infrastructure/ProcessManager.ts
@@ -326,11 +326,9 @@ export async function waitForProcessesExit(pids: number[], timeoutMs: number): P
       try {
         process.kill(pid, 0);
         return true;
-      } catch (error: unknown) {
+      } catch {
         // process.kill(pid, 0) throws when PID doesn't exist — expected during cleanup
-        if (error instanceof Error) {
-          logger.debug('SYSTEM', `Process ${pid} no longer exists`, { pid, error: error.message });
-        }
+        // [ANTI-PATTERN IGNORED]: Tight loop checking 100s of PIDs every 100ms during cleanup
         return false;
       }
     });
diff --git a/src/services/sqlite/migrations/runner.ts b/src/services/sqlite/migrations/runner.ts
index 60547981..43b7a1b1 100644
--- a/src/services/sqlite/migrations/runner.ts
+++ b/src/services/sqlite/migrations/runner.ts
@@ -421,7 +421,7 @@ export class MigrationRunner {
     try {
       this.createUserPromptsFTS();
     } catch (ftsError) {
-      logger.warn('DB', 'FTS5 not available — user_prompts_fts skipped (search uses ChromaDB)', {}, ftsError instanceof Error ? ftsError : undefined);
+      logger.warn('DB', 'FTS5 not available — user_prompts_fts skipped (search uses ChromaDB)', {}, ftsError instanceof Error ? ftsError : new Error(String(ftsError)));
     }
 
     // Commit transaction
diff --git a/src/services/sync/ChromaSync.ts b/src/services/sync/ChromaSync.ts
index d2996c25..8c7fa961 100644
--- a/src/services/sync/ChromaSync.ts
+++ b/src/services/sync/ChromaSync.ts
@@ -565,7 +565,7 @@ export class ChromaSync {
     try {
       await this.runBackfillPipeline(db, backfillProject, existing);
     } catch (error) {
-      logger.error('CHROMA_SYNC', 'Backfill failed', { project: backfillProject }, error as Error);
+      logger.error('CHROMA_SYNC', 'Backfill failed', { project: backfillProject }, error instanceof Error ? error : new Error(String(error)));
       throw new Error(`Backfill failed: ${error instanceof Error ? error.message : String(error)}`);
     } finally {
       db.close();
diff --git a/src/services/worker/GeminiAgent.ts b/src/services/worker/GeminiAgent.ts
index 85fc7df8..3cf48b5b 100644
--- a/src/services/worker/GeminiAgent.ts
+++ b/src/services/worker/GeminiAgent.ts
@@ -374,7 +374,7 @@ export class GeminiAgent {
       return this.fallbackAgent.startSession(session, worker);
     }
 
-    logger.failure('SDK', 'Gemini agent error', { sessionDbId: session.sessionDbId }, error as Error);
+    logger.failure('SDK', 'Gemini agent error', { sessionDbId: session.sessionDbId }, error instanceof Error ? error : new Error(String(error)));
     throw error;
   }
 
diff --git a/src/services/worker/OpenRouterAgent.ts b/src/services/worker/OpenRouterAgent.ts
index 8e2917af..98133b9b 100644
--- a/src/services/worker/OpenRouterAgent.ts
+++ b/src/services/worker/OpenRouterAgent.ts
@@ -345,7 +345,7 @@ export class OpenRouterAgent {
       return;
     }
 
-    logger.failure('SDK', 'OpenRouter agent error', { sessionDbId: session.sessionDbId }, error as Error);
+    logger.failure('SDK', 'OpenRouter agent error', { sessionDbId: session.sessionDbId }, error instanceof Error ? error : new Error(String(error)));
     throw error;
   }
 
diff --git a/src/utils/logger.ts b/src/utils/logger.ts
index c024e350..49bd2336 100644
--- a/src/utils/logger.ts
+++ b/src/utils/logger.ts
@@ -154,11 +154,7 @@ class Logger {
       try {
         input = JSON.parse(toolInput);
       } catch (_parseError: unknown) {
-        // [ANTI-PATTERN IGNORED]: Logger cannot log its own failures, using stderr/console as last resort
-        // Input is a raw string (e.g., Bash command), use as-is
-        if (_parseError instanceof Error) {
-          console.error('[logger] JSON parse failed for tool input:', _parseError);
-        }
+        // Input is a raw string (e.g., Bash command), use as-is — JSON.parse failure is expected here
         input = toolInput;
       }
     }