feat(start-block): add run metadata toggle with trusted <start.metadata> outputs

apps/sim/blocks/blocks/start_trigger.ts

@@ -25,6 +25,15 @@ export const StartTriggerBlock: BlockConfig = {
       type: 'input-format',
       description: 'Add custom fields beyond the built-in input, conversationId, and files fields.',
     },
+    {
+      id: 'runMetadata',
+      title: 'Add run metadata',
+      type: 'switch',
+      mode: 'advanced',
+      defaultValue: false,
+      description:
+        'Expose trusted, server-injected run metadata under <start.metadata>: userEmail, workspaceId, workflowId, executionId, executionType, executionMode, startTime. Fields describe the invoking run — inside a custom block they identify the calling user and workflow.',
+    },
   ],
   tools: {
     access: [],

apps/sim/executor/execution/executor.ts

@@ -436,6 +436,7 @@ export class DAGExecutor {
           this.contextExtensions.metadata?.useDraftState ??
           this.contextExtensions.isDeployedContext !== true,
       },
+      startRunMetadata: this.contextExtensions.startRunMetadata,
       environmentVariables: this.environmentVariables,
       workflowVariables: this.workflowVariables,
       decisions: {
@@ -620,6 +621,7 @@ export class DAGExecutor {
     const blockOutput = buildStartBlockOutput({
       resolution: startResolution,
       workflowInput: this.workflowInput,
+      runMetadata: this.contextExtensions.startRunMetadata,
     })
 
     state.setBlockState(startResolution.block.id, {

apps/sim/executor/execution/types.ts

@@ -6,6 +6,7 @@ import type {
   BlockLog,
   BlockState,
   NormalizedBlockOutput,
+  StartBlockRunMetadata,
   StreamingExecution,
 } from '@/executor/types'
 import type { RunFromBlockContext } from '@/executor/utils/run-from-block'
@@ -192,6 +193,12 @@ export interface ContextExtensions {
   dagIncomingEdges?: Record<string, string[]>
   snapshotState?: SerializableExecutionState
   metadata?: ExecutionMetadata
+  /**
+   * Trusted run metadata injected into the Start block output when its
+   * "Add run metadata" toggle is enabled. Built server-side at the two
+   * Executor construction sites — never from caller-supplied input.
+   */
+  startRunMetadata?: StartBlockRunMetadata
   /**
    * AbortSignal for cancellation support.
    * When aborted, the execution should stop gracefully.