fix: address PR feedback - periodic size checks and error handling

Changes based on code review feedback:

1. Made size check periodic in loop.ts (every 10 iterations)
   - Avoids expensive JSON.stringify on every iteration
   - Matches pattern used in block-executor.ts (every 50 logs)

2. Fixed error handling in estimateObjectSize/estimateBlockLogsSize
   - Now returns MAX + 1 instead of MAX on serialization failure
   - Ensures `size > MAX` evaluates to true, triggering cleanup
   - Prevents circular references from silently bypassing limits

Note: Array slicing logic is correct as-is:
- `.slice(discardCount)` keeps indices discardCount to end (newest)
- This is intended behavior: keep recent data, discard old

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: aadamsx

apps/sim/executor/execution/block-executor.ts

@@ -700,12 +700,14 @@ export class BlockExecutor {
 
   /**
    * Estimates the memory size of block logs in bytes.
+   * Returns a value exceeding the limit on serialization failure to trigger cleanup.
    */
   private estimateBlockLogsSize(logs: BlockLog[]): number {
     try {
       return JSON.stringify(logs).length * 2
     } catch {
-      return DEFAULTS.MAX_BLOCK_LOGS_SIZE_BYTES
+      // Return a value that exceeds the limit to trigger cleanup on serialization failure
+      return DEFAULTS.MAX_BLOCK_LOGS_SIZE_BYTES + 1
     }
   }
 }

apps/sim/executor/orchestrators/loop.ts

@@ -493,21 +493,23 @@ export class LoopOrchestrator {
       })
     }
 
-    // Check memory size limit (approximate)
-    const estimatedSize = this.estimateObjectSize(scope.allIterationOutputs)
-    if (estimatedSize > DEFAULTS.MAX_ITERATION_OUTPUTS_SIZE_BYTES) {
-      // Discard oldest half of iterations when memory limit exceeded
-      const halfLength = Math.floor(scope.allIterationOutputs.length / 2)
-      const discardCount = Math.max(halfLength, 1)
-      scope.allIterationOutputs = scope.allIterationOutputs.slice(discardCount)
-      logger.warn('Loop iteration outputs exceeded memory limit, discarding older iterations', {
-        loopId,
-        iteration: scope.iteration,
-        estimatedSizeBytes: estimatedSize,
-        maxSizeBytes: DEFAULTS.MAX_ITERATION_OUTPUTS_SIZE_BYTES,
-        discardedCount: discardCount,
-        retainedCount: scope.allIterationOutputs.length,
-      })
+    // Periodically check memory size limit (every 10 iterations to avoid frequent serialization)
+    if (scope.allIterationOutputs.length % 10 === 0) {
+      const estimatedSize = this.estimateObjectSize(scope.allIterationOutputs)
+      if (estimatedSize > DEFAULTS.MAX_ITERATION_OUTPUTS_SIZE_BYTES) {
+        // Discard oldest half of iterations when memory limit exceeded
+        const halfLength = Math.floor(scope.allIterationOutputs.length / 2)
+        const discardCount = Math.max(halfLength, 1)
+        scope.allIterationOutputs = scope.allIterationOutputs.slice(discardCount)
+        logger.warn('Loop iteration outputs exceeded memory limit, discarding older iterations', {
+          loopId,
+          iteration: scope.iteration,
+          estimatedSizeBytes: estimatedSize,
+          maxSizeBytes: DEFAULTS.MAX_ITERATION_OUTPUTS_SIZE_BYTES,
+          discardedCount: discardCount,
+          retainedCount: scope.allIterationOutputs.length,
+        })
+      }
     }
   }
 
@@ -522,9 +524,9 @@ export class LoopOrchestrator {
       // Multiply by 2 for UTF-16 encoding overhead in JS strings
       return JSON.stringify(obj).length * 2
     } catch {
-      // If serialization fails (circular refs, etc.), return a large estimate
-      // to trigger cleanup as a safety measure
-      return DEFAULTS.MAX_ITERATION_OUTPUTS_SIZE_BYTES
+      // If serialization fails (circular refs, etc.), return a value that exceeds
+      // the limit to trigger cleanup as a safety measure
+      return DEFAULTS.MAX_ITERATION_OUTPUTS_SIZE_BYTES + 1
     }
   }
 }