Harden Copilot error and VFS handling

apps/sim/lib/copilot/application/error.ts

@@ -20,6 +20,27 @@ export function messageForCopilotApplicationError(
   if (classified && classified.code !== 'internal') {
     return classified.message
   }
-  trace.getActiveSpan()?.recordException(toError(error))
+  trace.getActiveSpan()?.recordException(flattenErrorChain(error))
   return fallback
 }
+
+/**
+ * Wrapper errors (Drizzle's "Failed query: <sql>") bury the actionable cause —
+ * the Postgres constraint/violation — in `cause`. Join the chain so the span
+ * exception carries the part an investigator actually needs.
+ */
+function flattenErrorChain(error: unknown): Error {
+  const primary = toError(error)
+  const parts = [primary.message]
+  let cursor: unknown = primary.cause
+  let depth = 0
+  while (cursor && depth < 4) {
+    parts.push(toError(cursor).message)
+    cursor = toError(cursor).cause
+    depth += 1
+  }
+  if (parts.length === 1) return primary
+  const flattened = new Error(parts.join(' ← '))
+  flattened.stack = primary.stack
+  return flattened
+}

apps/sim/lib/copilot/vfs/workspace-vfs.ts

@@ -1806,11 +1806,24 @@ export class WorkspaceVFS {
           })
         }
 
+        // deployment.json exists for EVERY workflow: "is it deployed?" is a
+        // question with an answer either way, and a not-found error here was a
+        // recurring red herring — agents probing an undeployed workflow read a
+        // failure instead of the fact. Versions stay gated: they genuinely
+        // don't exist before the first deploy.
+        this.registerLazy(`${prefix}deployment.json`, async () => {
+          if (!versionedWorkflowIds.has(wf.id)) {
+            return JSON.stringify({
+              deployed: false,
+              note: 'This workflow has never been deployed.',
+            })
+          }
+          const deploymentData = await this.loadDeployments(wf.id)
+          return deploymentData
+            ? serializeDeployments(deploymentData)
+            : JSON.stringify({ deployed: false, note: 'This workflow has never been deployed.' })
+        })
         if (versionedWorkflowIds.has(wf.id)) {
-          this.registerLazy(`${prefix}deployment.json`, async () => {
-            const deploymentData = await this.loadDeployments(wf.id)
-            return deploymentData ? serializeDeployments(deploymentData) : null
-          })
           this.registerLazy(`${prefix}versions.json`, async () => {
             const deploymentData = await this.loadDeployments(wf.id)
             return deploymentData?.versions && deploymentData.versions.length > 0