fix(terminal): start precision (#3078)

* fix(executor): use performance.now() for precise block timing

Replace Date.now() with performance.now() for timing measurements in
the executor to provide sub-millisecond precision. This fixes timing
discrepancies with fast-executing blocks like the start block where
millisecond precision was insufficient.

Changes:
- block-executor.ts: Use performance.now() for block execution timing
- engine.ts: Use performance.now() for overall execution timing

Co-authored-by: emir <emir@simstudio.ai>

* format ms as whole nums,round secs to 2 decimal places and compute all started/ended times on server and passback to clinet

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: waleed <walif6@gmail.com>

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

@@ -71,7 +71,7 @@ export class BlockExecutor {
       this.callOnBlockStart(ctx, node, block)
     }
 
-    const startTime = Date.now()
+    const startTime = performance.now()
     let resolvedInputs: Record<string, any> = {}
 
     const nodeMetadata = this.buildNodeMetadata(node)
@@ -145,7 +145,7 @@ export class BlockExecutor {
         })) as NormalizedBlockOutput
       }
 
-      const duration = Date.now() - startTime
+      const duration = performance.now() - startTime
 
       if (blockLog) {
         blockLog.endedAt = new Date().toISOString()
@@ -169,7 +169,9 @@ export class BlockExecutor {
           block,
           this.sanitizeInputsForLog(resolvedInputs),
           displayOutput,
-          duration
+          duration,
+          blockLog!.startedAt,
+          blockLog!.endedAt
         )
       }
 
@@ -221,7 +223,7 @@ export class BlockExecutor {
     isSentinel: boolean,
     phase: 'input_resolution' | 'execution'
   ): NormalizedBlockOutput {
-    const duration = Date.now() - startTime
+    const duration = performance.now() - startTime
     const errorMessage = normalizeError(error)
     const hasResolvedInputs =
       resolvedInputs && typeof resolvedInputs === 'object' && Object.keys(resolvedInputs).length > 0
@@ -274,7 +276,9 @@ export class BlockExecutor {
         block,
         this.sanitizeInputsForLog(input),
         displayOutput,
-        duration
+        duration,
+        blockLog!.startedAt,
+        blockLog!.endedAt
       )
     }
 
@@ -423,7 +427,9 @@ export class BlockExecutor {
     block: SerializedBlock,
     input: Record<string, any>,
     output: NormalizedBlockOutput,
-    duration: number
+    duration: number,
+    startedAt: string,
+    endedAt: string
   ): void {
     const blockId = node.id
     const blockName = block.metadata?.name ?? blockId
@@ -440,6 +446,8 @@ export class BlockExecutor {
           input,
           output,
           executionTime: duration,
+          startedAt,
+          endedAt,
         },
         iterationContext
       )

apps/sim/executor/execution/engine.ts

@@ -101,7 +101,7 @@ export class ExecutionEngine {
   }
 
   async run(triggerBlockId?: string): Promise<ExecutionResult> {
-    const startTime = Date.now()
+    const startTime = performance.now()
     try {
       this.initializeQueue(triggerBlockId)
 
@@ -125,8 +125,8 @@ export class ExecutionEngine {
         return this.buildPausedResult(startTime)
       }
 
-      const endTime = Date.now()
-      this.context.metadata.endTime = new Date(endTime).toISOString()
+      const endTime = performance.now()
+      this.context.metadata.endTime = new Date().toISOString()
       this.context.metadata.duration = endTime - startTime
 
       if (this.cancelledFlag) {
@@ -146,8 +146,8 @@ export class ExecutionEngine {
         metadata: this.context.metadata,
       }
     } catch (error) {
-      const endTime = Date.now()
-      this.context.metadata.endTime = new Date(endTime).toISOString()
+      const endTime = performance.now()
+      this.context.metadata.endTime = new Date().toISOString()
       this.context.metadata.duration = endTime - startTime
 
       if (this.cancelledFlag) {
@@ -433,8 +433,8 @@ export class ExecutionEngine {
   }
 
   private buildPausedResult(startTime: number): ExecutionResult {
-    const endTime = Date.now()
-    this.context.metadata.endTime = new Date(endTime).toISOString()
+    const endTime = performance.now()
+    this.context.metadata.endTime = new Date().toISOString()
     this.context.metadata.duration = endTime - startTime
     this.context.metadata.status = 'paused'
 

apps/sim/executor/execution/types.ts

@@ -103,7 +103,13 @@ export interface ContextExtensions {
     blockId: string,
     blockName: string,
     blockType: string,
-    output: { input?: any; output: NormalizedBlockOutput; executionTime: number },
+    output: {
+      input?: any
+      output: NormalizedBlockOutput
+      executionTime: number
+      startedAt: string
+      endedAt: string
+    },
     iterationContext?: IterationContext
   ) => Promise<void>
 

apps/sim/executor/orchestrators/loop.ts

@@ -281,9 +281,12 @@ export class LoopOrchestrator {
 
     // Emit onBlockComplete for the loop container so the UI can track it
     if (this.contextExtensions?.onBlockComplete) {
+      const now = new Date().toISOString()
       this.contextExtensions.onBlockComplete(loopId, 'Loop', 'loop', {
         output,
         executionTime: DEFAULTS.EXECUTION_TIME,
+        startedAt: now,
+        endedAt: now,
       })
     }
 

apps/sim/executor/orchestrators/parallel.ts

@@ -265,9 +265,12 @@ export class ParallelOrchestrator {
 
     // Emit onBlockComplete for the parallel container so the UI can track it
     if (this.contextExtensions?.onBlockComplete) {
+      const now = new Date().toISOString()
       this.contextExtensions.onBlockComplete(parallelId, 'Parallel', 'parallel', {
         output,
         executionTime: 0,
+        startedAt: now,
+        endedAt: now,
       })
     }
 

apps/sim/executor/utils/subflow-utils.ts

@@ -232,6 +232,8 @@ export function addSubflowErrorLog(
       input: inputData,
       output: { error: errorMessage },
       executionTime: 0,
+      startedAt: now,
+      endedAt: now,
     })
   }
 }