fix(child-workflow): nested spans handoff

apps/sim/executor/errors/child-workflow-error.ts

@@ -0,0 +1,31 @@
+import type { TraceSpan } from '@/lib/logs/types'
+import type { ExecutionResult } from '@/executor/types'
+
+interface ChildWorkflowErrorOptions {
+  message: string
+  childWorkflowName: string
+  childTraceSpans?: TraceSpan[]
+  executionResult?: ExecutionResult
+  cause?: Error
+}
+
+/**
+ * Error raised when a child workflow execution fails.
+ */
+export class ChildWorkflowError extends Error {
+  readonly childTraceSpans: TraceSpan[]
+  readonly childWorkflowName: string
+  readonly executionResult?: ExecutionResult
+
+  constructor(options: ChildWorkflowErrorOptions) {
+    super(options.message, { cause: options.cause })
+    this.name = 'ChildWorkflowError'
+    this.childWorkflowName = options.childWorkflowName
+    this.childTraceSpans = options.childTraceSpans ?? []
+    this.executionResult = options.executionResult
+  }
+
+  static isChildWorkflowError(error: unknown): error is ChildWorkflowError {
+    return error instanceof ChildWorkflowError
+  }
+}

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

@@ -13,6 +13,7 @@ import {
   isSentinelBlockType,
 } from '@/executor/constants'
 import type { DAGNode } from '@/executor/dag/builder'
+import { ChildWorkflowError } from '@/executor/errors/child-workflow-error'
 import type { BlockStateWriter, ContextExtensions } from '@/executor/execution/types'
 import {
   generatePauseContextId,
@@ -213,24 +214,28 @@ export class BlockExecutor {
         ? resolvedInputs
         : ((block.config?.params as Record<string, any> | undefined) ?? {})
 
+    const errorOutput: NormalizedBlockOutput = {
+      error: errorMessage,
+    }
+
+    if (ChildWorkflowError.isChildWorkflowError(error)) {
+      errorOutput.childTraceSpans = error.childTraceSpans
+      errorOutput.childWorkflowName = error.childWorkflowName
+    } else if (error && typeof error === 'object' && 'childTraceSpans' in error) {
+      errorOutput.childTraceSpans = (error as any).childTraceSpans
+    }
+
+    this.state.setBlockOutput(node.id, errorOutput, duration)
+
     if (blockLog) {
       blockLog.endedAt = new Date().toISOString()
       blockLog.durationMs = duration
       blockLog.success = false
       blockLog.error = errorMessage
       blockLog.input = input
+      blockLog.output = this.filterOutputForLog(block, errorOutput)
     }
 
-    const errorOutput: NormalizedBlockOutput = {
-      error: errorMessage,
-    }
-
-    if (error && typeof error === 'object' && 'childTraceSpans' in error) {
-      errorOutput.childTraceSpans = (error as any).childTraceSpans
-    }
-
-    this.state.setBlockOutput(node.id, errorOutput, duration)
-
     logger.error(
       phase === 'input_resolution' ? 'Failed to resolve block inputs' : 'Block execution failed',
       {

apps/sim/executor/handlers/workflow/workflow-handler.ts

@@ -4,6 +4,7 @@ import type { TraceSpan } from '@/lib/logs/types'
 import type { BlockOutput } from '@/blocks/types'
 import { Executor } from '@/executor'
 import { BlockType, DEFAULTS, HTTP } from '@/executor/constants'
+import { ChildWorkflowError } from '@/executor/errors/child-workflow-error'
 import type {
   BlockHandler,
   ExecutionContext,
@@ -145,31 +146,30 @@ export class WorkflowBlockHandler implements BlockHandler {
       const childWorkflowName = workflowMetadata?.name || workflowId
 
       const originalError = error.message || 'Unknown error'
-      const wrappedError = new Error(
-        `Error in child workflow "${childWorkflowName}": ${originalError}`
-      )
-
+      let childTraceSpans: WorkflowTraceSpan[] = []
+      let executionResult: ExecutionResult | undefined
       if (error.executionResult?.logs) {
-        const executionResult = error.executionResult as ExecutionResult
+        executionResult = error.executionResult as ExecutionResult
 
         logger.info(`Extracting child trace spans from error.executionResult`, {
           hasLogs: (executionResult.logs?.length ?? 0) > 0,
           logCount: executionResult.logs?.length ?? 0,
         })
 
-        const childTraceSpans = this.captureChildWorkflowLogs(
-          executionResult,
-          childWorkflowName,
-          ctx
-        )
+        childTraceSpans = this.captureChildWorkflowLogs(executionResult, childWorkflowName, ctx)
 
         logger.info(`Captured ${childTraceSpans.length} child trace spans from failed execution`)
-        ;(wrappedError as any).childTraceSpans = childTraceSpans
       } else if (error.childTraceSpans && Array.isArray(error.childTraceSpans)) {
-        ;(wrappedError as any).childTraceSpans = error.childTraceSpans
+        childTraceSpans = error.childTraceSpans
       }
 
-      throw wrappedError
+      throw new ChildWorkflowError({
+        message: `Error in child workflow "${childWorkflowName}": ${originalError}`,
+        childWorkflowName,
+        childTraceSpans,
+        executionResult,
+        cause: error,
+      })
     }
   }
 
@@ -441,11 +441,11 @@ export class WorkflowBlockHandler implements BlockHandler {
 
     if (!success) {
       logger.warn(`Child workflow ${childWorkflowName} failed`)
-      const error = new Error(
-        `Error in child workflow "${childWorkflowName}": ${childResult.error || 'Child workflow execution failed'}`
-      )
-      ;(error as any).childTraceSpans = childTraceSpans || []
-      throw error
+      throw new ChildWorkflowError({
+        message: `Error in child workflow "${childWorkflowName}": ${childResult.error || 'Child workflow execution failed'}`,
+        childWorkflowName,
+        childTraceSpans: childTraceSpans || [],
+      })
     }
 
     return {