Proper error stack propogating (#280)

* Proper stacktrace propogation in world

Proper stacktrace propogation in world

* Merge Reconciliation

* Standardize the error type in the world spec

* Deduplicate vercel world utils

* fix undefined type issue

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>

Author: pranaygp

.changeset/cruel-houses-sneeze.md

@@ -0,0 +1,5 @@
+---
+"@workflow/world-local": patch
+---
+
+Support for structured errors

.changeset/fix-error-stack-rendering.md

@@ -0,0 +1,5 @@
+---
+"@workflow/web-shared": patch
+---
+
+Support structured error rendering

.changeset/good-icons-love.md

@@ -0,0 +1,5 @@
+---
+"@workflow/core": patch
+---
+
+Implement the world's structured error interface

.changeset/postgres-error-stack.md

@@ -0,0 +1,5 @@
+---
+"@workflow/world-postgres": patch
+---
+
+Support structured errors for steps and runs

.changeset/sour-tigers-serve.md

@@ -0,0 +1,5 @@
+---
+"@workflow/errors": patch
+---
+
+Wire through world's structured errors in WorkflowRunFailedError

.changeset/witty-vans-report.md

@@ -0,0 +1,5 @@
+---
+"@workflow/world": patch
+---
+
+Add error stack propogation to steps and runs

.changeset/world-vercel-error-serialization.md

@@ -0,0 +1,5 @@
+---
+"@workflow/world-vercel": patch
+---
+
+Support structured errors for steps and runs

CLAUDE.md

@@ -160,4 +160,5 @@ This project uses pnpm with workspace configuration. The required version is spe
   - All changed packages should be included in the changeset. Never include unchanged packages.
   - All changes should be marked as "patch". Never use "major" or "minor" modes.
 - Remember to always build any packages that get changed before running downstream tests like e2e tests in the workbench
-- Remember that changes made to one workbench should propogate to all other workbenches. The workflows should typically only be written once inside the example workbench and symlinked into all the other workbenches
+- Remember that changes made to one workbench should propogate to all other workbenches. The workflows should typically only be written once inside the example workbench and symlinked into all the other workbenches
+- When writing changeset, use the `pnpm changeset` command from the root of the repo. Keep the changesets terse (see existing changesets for examples). Try to amke chagnesets that are specific to each modified package so they are targeted. Ensure that any breaking changes are marked as "**BREAKING CHANGE**

packages/core/e2e/e2e.test.ts

@@ -561,13 +561,22 @@ describe('e2e', () => {
       const run = await triggerWorkflow('crossFileErrorWorkflow', []);
       const returnValue = await getWorkflowReturnValue(run.runId);
 
-      // The workflow should fail with the error from the helper module
-      expect(returnValue).toHaveProperty('error');
-      expect(returnValue.error).toContain('Error from imported helper module');
+      // The workflow should fail with error response containing both top-level and cause
+      expect(returnValue).toHaveProperty('name');
+      expect(returnValue.name).toBe('WorkflowRunFailedError');
+      expect(returnValue).toHaveProperty('message');
+
+      // Verify the cause property contains the structured error
+      expect(returnValue).toHaveProperty('cause');
+      expect(returnValue.cause).toBeTypeOf('object');
+      expect(returnValue.cause).toHaveProperty('message');
+      expect(returnValue.cause.message).toContain(
+        'Error from imported helper module'
+      );
 
-      // Verify the stack trace is present and shows correct file paths
-      expect(returnValue).toHaveProperty('stack');
-      expect(typeof returnValue.stack).toBe('string');
+      // Verify the stack trace is present in the cause
+      expect(returnValue.cause).toHaveProperty('stack');
+      expect(typeof returnValue.cause.stack).toBe('string');
 
       // Known issue: SvelteKit dev mode has incorrect source map mappings for bundled imports.
       // esbuild with bundle:true inlines helpers.ts but source maps incorrectly map to 99_e2e.ts
@@ -578,24 +587,27 @@ describe('e2e', () => {
 
       if (!isSvelteKitDevMode) {
         // Stack trace should include frames from the helper module (helpers.ts)
-        expect(returnValue.stack).toContain('helpers.ts');
+        expect(returnValue.cause.stack).toContain('helpers.ts');
       }
 
       // These checks should work in all modes
-      expect(returnValue.stack).toContain('throwError');
-      expect(returnValue.stack).toContain('callThrower');
+      expect(returnValue.cause.stack).toContain('throwError');
+      expect(returnValue.cause.stack).toContain('callThrower');
 
       // Stack trace should include frames from the workflow file (99_e2e.ts)
-      expect(returnValue.stack).toContain('99_e2e.ts');
-      expect(returnValue.stack).toContain('crossFileErrorWorkflow');
+      expect(returnValue.cause.stack).toContain('99_e2e.ts');
+      expect(returnValue.cause.stack).toContain('crossFileErrorWorkflow');
 
       // Stack trace should NOT contain 'evalmachine' anywhere
-      expect(returnValue.stack).not.toContain('evalmachine');
+      expect(returnValue.cause.stack).not.toContain('evalmachine');
 
-      // Verify the run failed
+      // Verify the run failed with structured error
       const { json: runData } = await cliInspectJson(`runs ${run.runId}`);
       expect(runData.status).toBe('failed');
-      expect(runData.error).toContain('Error from imported helper module');
+      expect(runData.error).toBeTypeOf('object');
+      expect(runData.error.message).toContain(
+        'Error from imported helper module'
+      );
     }
   );
 });

packages/core/src/runtime.ts

@@ -17,6 +17,7 @@ import type {
 } from '@workflow/world';
 import { WorkflowSuspension } from './global.js';
 import { runtimeLogger } from './logger.js';
+import { parseWorkflowName } from './parse-name.js';
 import { getStepFunction } from './private.js';
 import { getWorld, getWorldHandlers } from './runtime/world.js';
 import {
@@ -33,6 +34,7 @@ import {
   hydrateStepArguments,
   hydrateWorkflowReturnValue,
 } from './serialization.js';
+import { remapErrorStack } from './source-map.js';
 // TODO: move step handler out to a separate file
 import { contextStorage } from './step/context-storage.js';
 import * as Attribute from './telemetry/semantic-conventions.js';
@@ -43,8 +45,6 @@ import {
   getWorkflowRunStreamId,
 } from './util.js';
 import { runWorkflow } from './workflow.js';
-import { remapErrorStack } from './source-map.js';
-import { parseWorkflowName } from './parse-name.js';
 
 export type { Event, WorkflowRun };
 export { WorkflowSuspension } from './global.js';
@@ -205,10 +205,7 @@ export class Run<TResult> {
         }
 
         if (run.status === 'failed') {
-          throw new WorkflowRunFailedError(
-            this.runId,
-            run.error ?? 'Unknown error'
-          );
+          throw new WorkflowRunFailedError(this.runId, run.error);
         }
 
         throw new WorkflowRunNotCompletedError(this.runId, run.status);
@@ -520,6 +517,8 @@ export function workflowEntrypoint(workflowCode: string) {
               }
             } else {
               const errorName = getErrorName(err);
+              const errorMessage =
+                err instanceof Error ? err.message : String(err);
               let errorStack = getErrorStack(err);
 
               // Remap error stack using source maps to show original source locations
@@ -536,14 +535,13 @@ export function workflowEntrypoint(workflowCode: string) {
               console.error(
                 `${errorName} while running "${runId}" workflow:\n\n${errorStack}`
               );
-
-              // Store both the error message and remapped stack trace
-              const errorString = errorStack || String(err);
-
               await world.runs.update(runId, {
                 status: 'failed',
-                error: errorString,
-                // TODO: include error codes when we define them
+                error: {
+                  message: errorMessage,
+                  stack: errorStack,
+                  // TODO: include error codes when we define them
+                },
               });
               span?.setAttributes({
                 ...Attribute.WorkflowRunStatus('failed'),
@@ -739,7 +737,8 @@ export const stepEntrypoint =
             }
 
             if (FatalError.is(err)) {
-              const stackLines = getErrorStack(err).split('\n').slice(0, 4);
+              const errorStack = getErrorStack(err);
+              const stackLines = errorStack.split('\n').slice(0, 4);
               console.error(
                 `[Workflows] "${workflowRunId}" - Encountered \`FatalError\` while executing step "${stepName}":\n  > ${stackLines.join('\n    > ')}\n\nBubbling up error to parent workflow`
               );
@@ -749,15 +748,17 @@ export const stepEntrypoint =
                 correlationId: stepId,
                 eventData: {
                   error: String(err),
-                  stack: err.stack,
+                  stack: errorStack,
                   fatal: true,
                 },
               });
               await world.steps.update(workflowRunId, stepId, {
                 status: 'failed',
-                error: String(err),
-                // TODO: include error codes when we define them
-                // TODO: serialize/include the error name and stack?
+                error: {
+                  message: err.message || String(err),
+                  stack: errorStack,
+                  // TODO: include error codes when we define them
+                },
               });
 
               span?.setAttributes({
@@ -774,7 +775,8 @@ export const stepEntrypoint =
 
               if (attempt >= maxRetries) {
                 // Max retries reached
-                const stackLines = getErrorStack(err).split('\n').slice(0, 4);
+                const errorStack = getErrorStack(err);
+                const stackLines = errorStack.split('\n').slice(0, 4);
                 console.error(
                   `[Workflows] "${workflowRunId}" - Encountered \`Error\` while executing step "${stepName}" (attempt ${attempt}):\n  > ${stackLines.join('\n    > ')}\n\n  Max retries reached\n  Bubbling error to parent workflow`
                 );
@@ -784,13 +786,16 @@ export const stepEntrypoint =
                   correlationId: stepId,
                   eventData: {
                     error: errorMessage,
-                    stack: getErrorStack(err),
+                    stack: errorStack,
                     fatal: true,
                   },
                 });
                 await world.steps.update(workflowRunId, stepId, {
                   status: 'failed',
-                  error: errorMessage,
+                  error: {
+                    message: errorMessage,
+                    stack: errorStack,
+                  },
                 });
 
                 span?.setAttributes({