From 7c481b09b294a2a61dcac42f8313065dc51dfb92 Mon Sep 17 00:00:00 2001
From: Kyle Mathews <mathews.kyle@gmail.com>
Date: Thu, 11 Jun 2026 08:45:56 -0600
Subject: [PATCH 1/4] Fix persisted run error rendering

---
 packages/agents-runtime/src/process-wake.ts   | 34 +++++++++++++++
 .../src/components/AgentResponse.module.css   | 36 ++++++++++++++++
 .../src/components/AgentResponse.tsx          | 41 ++++++++++++++-----
 3 files changed, 101 insertions(+), 10 deletions(-)

diff --git a/packages/agents-runtime/src/process-wake.ts b/packages/agents-runtime/src/process-wake.ts
index c419a3114a..a5b193ff9b 100644
--- a/packages/agents-runtime/src/process-wake.ts
+++ b/packages/agents-runtime/src/process-wake.ts
@@ -146,6 +146,35 @@ function toError(err: unknown): Error {
   return err instanceof Error ? err : new Error(String(err))
 }
 
+function compareRunOrder(
+  left: { key: string; _timeline_order?: string; _seq?: number },
+  right: { key: string; _timeline_order?: string; _seq?: number }
+): number {
+  if (left._timeline_order && right._timeline_order) {
+    return left._timeline_order.localeCompare(right._timeline_order)
+  }
+  if (left._timeline_order) return 1
+  if (right._timeline_order) return -1
+
+  if (left._seq !== undefined && right._seq !== undefined) {
+    return left._seq - right._seq
+  }
+  if (left._seq !== undefined) return 1
+  if (right._seq !== undefined) return -1
+
+  return left.key.localeCompare(right.key)
+}
+
+function latestNewRunKey(
+  db: EntityStreamDBWithActions,
+  existingRunKeys: ReadonlySet<string>
+): string | undefined {
+  return db.collections.runs.toArray
+    .filter((run) => !existingRunKeys.has(run.key))
+    .sort(compareRunOrder)
+    .at(-1)?.key
+}
+
 async function resolveHeadersProvider(
   provider: ProcessWakeConfig[`claimHeaders`]
 ): Promise<Record<string, string> | undefined> {
@@ -2158,6 +2187,9 @@ export async function processWake(
       })
 
       let sleepRequested = false
+      const existingRunKeys = new Set(
+        db.collections.runs.toArray.map((run) => run.key)
+      )
 
       try {
         await wirePendingSharedStates()
@@ -2208,12 +2240,14 @@ export async function processWake(
             ? setupErr.code
             : `HANDLER_FAILED`
         log.error(`handler failed for ${entityUrl}:`, errMsg)
+        const failedRunKey = latestNewRunKey(db, existingRunKeys)
         writeEvent(
           entityStateSchema.errors.insert({
             key: `error-${epoch}-${crypto.randomUUID()}`,
             value: {
               error_code: errCode,
               message: errMsg,
+              ...(failedRunKey ? { run_id: failedRunKey } : {}),
             } as never,
           }) as ChangeEvent
         )
diff --git a/packages/agents-server-ui/src/components/AgentResponse.module.css b/packages/agents-server-ui/src/components/AgentResponse.module.css
index 36141e7b86..e80c0ec2cf 100644
--- a/packages/agents-server-ui/src/components/AgentResponse.module.css
+++ b/packages/agents-server-ui/src/components/AgentResponse.module.css
@@ -48,3 +48,39 @@
 .metaActionButton:hover {
   opacity: 1;
 }
+
+.errorText {
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.errorDetails {
+  min-width: 0;
+  max-width: 100%;
+}
+
+.errorDetails summary {
+  cursor: pointer;
+  list-style-position: outside;
+  padding-left: 2px;
+}
+
+.errorSummaryText {
+  display: inline;
+}
+
+.errorPre {
+  margin: 8px 0 0;
+  max-width: 100%;
+  overflow: auto;
+  white-space: pre-wrap;
+  word-break: break-word;
+  color: var(--ds-red-11);
+  background: var(--ds-red-2);
+  border: 1px solid var(--ds-red-6);
+  border-radius: 8px;
+  padding: 8px 10px;
+  font: 12px/1.45 var(--ds-font-mono);
+}
diff --git a/packages/agents-server-ui/src/components/AgentResponse.tsx b/packages/agents-server-ui/src/components/AgentResponse.tsx
index 673e9cb496..8a49681df7 100644
--- a/packages/agents-server-ui/src/components/AgentResponse.tsx
+++ b/packages/agents-server-ui/src/components/AgentResponse.tsx
@@ -334,6 +334,35 @@ function errorText(errors: Array<EntityTimelineErrorItem>): string | undefined {
   return errors.length > 0 ? errors.map(formatError).join(`; `) : undefined
 }
 
+function RunErrorMessage({ message }: { message: string }): React.ReactElement {
+  const maxSummaryLength = 180
+  const isLong = message.length > maxSummaryLength || message.includes(`\n`)
+  if (!isLong) {
+    return (
+      <Text size={1} tone="danger" className={styles.errorText}>
+        ✗ {message}
+      </Text>
+    )
+  }
+
+  const normalizedSummary = message.replace(/\s+/g, ` `)
+  const isTruncated = normalizedSummary.length > maxSummaryLength
+  const summary = isTruncated
+    ? normalizedSummary.slice(0, maxSummaryLength)
+    : normalizedSummary
+  return (
+    <details className={styles.errorDetails}>
+      <summary>
+        <Text size={1} tone="danger" className={styles.errorSummaryText}>
+          ✗ {summary}
+          {isTruncated ? `…` : ``}
+        </Text>
+      </summary>
+      <pre className={styles.errorPre}>{message}</pre>
+    </details>
+  )
+}
+
 function failedRunText(
   run: EntityTimelineRunRow,
   items: Array<EntityTimelineRunItem>
@@ -530,11 +559,7 @@ export const AgentResponseLive = memo(function AgentResponseLive({
               : `✓ done`}
           </Text>
         )}
-        {failureText && (
-          <Text size={1} tone="danger">
-            ✗ {failureText}
-          </Text>
-        )}
+        {failureText && <RunErrorMessage message={failureText} />}
         {/* Elapsed-time ticker — visible while the response is still
             in flight so the user can see how long the model has been
             working ("Thinking · 12s", or just "12s" once tokens are
@@ -748,11 +773,7 @@ export const AgentResponse = memo(function AgentResponse({
               : `✓ done`}
           </Text>
         )}
-        {section.error && (
-          <Text size={1} tone="danger">
-            ✗ {section.error}
-          </Text>
-        )}
+        {section.error && <RunErrorMessage message={section.error} />}
         {/* Elapsed-time ticker — kept in sync with the live variant
             above so cached sections (rare during streaming, but the
             type permits it) render the same meta row. */}

From 8e6120c7383e5f607631e372e719f4ed3b5ee381 Mon Sep 17 00:00:00 2001
From: Kyle Mathews <mathews.kyle@gmail.com>
Date: Thu, 11 Jun 2026 08:48:03 -0600
Subject: [PATCH 2/4] Add run error rendering changeset

---
 .changeset/run-error-rendering.md | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 .changeset/run-error-rendering.md

diff --git a/.changeset/run-error-rendering.md b/.changeset/run-error-rendering.md
new file mode 100644
index 0000000000..a70db787cb
--- /dev/null
+++ b/.changeset/run-error-rendering.md
@@ -0,0 +1,6 @@
+---
+'@electric-ax/agents-runtime': patch
+'@electric-ax/agents-server-ui': patch
+---
+
+Persist handler errors on the run that produced them and render long run error messages in the agents UI as expandable details.

From b20a74414eb4f1b09e17c030f898e011dff940e7 Mon Sep 17 00:00:00 2001
From: Kyle Mathews <mathews.kyle@gmail.com>
Date: Thu, 11 Jun 2026 08:53:57 -0600
Subject: [PATCH 3/4] Simplify failed run selection

---
 packages/agents-runtime/src/process-wake.ts | 20 --------------------
 1 file changed, 20 deletions(-)

diff --git a/packages/agents-runtime/src/process-wake.ts b/packages/agents-runtime/src/process-wake.ts
index a5b193ff9b..f9d94ee5b3 100644
--- a/packages/agents-runtime/src/process-wake.ts
+++ b/packages/agents-runtime/src/process-wake.ts
@@ -146,32 +146,12 @@ function toError(err: unknown): Error {
   return err instanceof Error ? err : new Error(String(err))
 }
 
-function compareRunOrder(
-  left: { key: string; _timeline_order?: string; _seq?: number },
-  right: { key: string; _timeline_order?: string; _seq?: number }
-): number {
-  if (left._timeline_order && right._timeline_order) {
-    return left._timeline_order.localeCompare(right._timeline_order)
-  }
-  if (left._timeline_order) return 1
-  if (right._timeline_order) return -1
-
-  if (left._seq !== undefined && right._seq !== undefined) {
-    return left._seq - right._seq
-  }
-  if (left._seq !== undefined) return 1
-  if (right._seq !== undefined) return -1
-
-  return left.key.localeCompare(right.key)
-}
-
 function latestNewRunKey(
   db: EntityStreamDBWithActions,
   existingRunKeys: ReadonlySet<string>
 ): string | undefined {
   return db.collections.runs.toArray
     .filter((run) => !existingRunKeys.has(run.key))
-    .sort(compareRunOrder)
     .at(-1)?.key
 }
 

From 65f6dcf651ec57cba7b4459fc482d1f2fc227eb9 Mon Sep 17 00:00:00 2001
From: Kyle Mathews <mathews.kyle@gmail.com>
Date: Thu, 11 Jun 2026 09:01:14 -0600
Subject: [PATCH 4/4] Use event card for long run errors

---
 .../src/components/AgentResponse.module.css   | 36 ---------
 .../src/components/AgentResponse.tsx          | 74 ++++++++++++-------
 2 files changed, 47 insertions(+), 63 deletions(-)

diff --git a/packages/agents-server-ui/src/components/AgentResponse.module.css b/packages/agents-server-ui/src/components/AgentResponse.module.css
index e80c0ec2cf..36141e7b86 100644
--- a/packages/agents-server-ui/src/components/AgentResponse.module.css
+++ b/packages/agents-server-ui/src/components/AgentResponse.module.css
@@ -48,39 +48,3 @@
 .metaActionButton:hover {
   opacity: 1;
 }
-
-.errorText {
-  min-width: 0;
-  overflow: hidden;
-  text-overflow: ellipsis;
-  white-space: nowrap;
-}
-
-.errorDetails {
-  min-width: 0;
-  max-width: 100%;
-}
-
-.errorDetails summary {
-  cursor: pointer;
-  list-style-position: outside;
-  padding-left: 2px;
-}
-
-.errorSummaryText {
-  display: inline;
-}
-
-.errorPre {
-  margin: 8px 0 0;
-  max-width: 100%;
-  overflow: auto;
-  white-space: pre-wrap;
-  word-break: break-word;
-  color: var(--ds-red-11);
-  background: var(--ds-red-2);
-  border: 1px solid var(--ds-red-6);
-  border-radius: 8px;
-  padding: 8px 10px;
-  font: 12px/1.45 var(--ds-font-mono);
-}
diff --git a/packages/agents-server-ui/src/components/AgentResponse.tsx b/packages/agents-server-ui/src/components/AgentResponse.tsx
index 8a49681df7..373d8ea64a 100644
--- a/packages/agents-server-ui/src/components/AgentResponse.tsx
+++ b/packages/agents-server-ui/src/components/AgentResponse.tsx
@@ -1,4 +1,4 @@
-import { Check, Copy, GitFork } from 'lucide-react'
+import { Check, Copy, CircleAlert, GitFork } from 'lucide-react'
 import {
   memo,
   useEffect,
@@ -23,12 +23,14 @@ import {
 } from '../lib/streamdownConfig'
 import { Icon, IconButton, Stack, Text, Tooltip } from '../ui'
 import { ToolCallView } from './ToolCallView'
+import { InlineEventCard } from './InlineEventCard'
 import { TimeText } from './TimeText'
 import { ThinkingIndicator } from './ThinkingIndicator'
 import { ElapsedTime } from './ElapsedTime'
 import { TokenUsage } from './TokenUsage'
 import { formatElapsedDuration, toMillis } from '../lib/formatTime'
 import styles from './AgentResponse.module.css'
+import toolBlock from './toolBlock.module.css'
 import type { ForkFromHereAction } from './UserMessage'
 import type {
   EntityTimelineContentItem,
@@ -334,32 +336,38 @@ function errorText(errors: Array<EntityTimelineErrorItem>): string | undefined {
   return errors.length > 0 ? errors.map(formatError).join(`; `) : undefined
 }
 
-function RunErrorMessage({ message }: { message: string }): React.ReactElement {
-  const maxSummaryLength = 180
-  const isLong = message.length > maxSummaryLength || message.includes(`\n`)
-  if (!isLong) {
-    return (
-      <Text size={1} tone="danger" className={styles.errorText}>
-        ✗ {message}
-      </Text>
-    )
-  }
+const RUN_ERROR_SUMMARY_LENGTH = 180
+
+function isLongRunError(message: string): boolean {
+  return message.length > RUN_ERROR_SUMMARY_LENGTH || message.includes(`\n`)
+}
 
-  const normalizedSummary = message.replace(/\s+/g, ` `)
-  const isTruncated = normalizedSummary.length > maxSummaryLength
-  const summary = isTruncated
-    ? normalizedSummary.slice(0, maxSummaryLength)
-    : normalizedSummary
+function runErrorSummary(message: string): string {
+  const normalized = message.replace(/\s+/g, ` `)
+  return normalized.length > RUN_ERROR_SUMMARY_LENGTH
+    ? `${normalized.slice(0, RUN_ERROR_SUMMARY_LENGTH)}…`
+    : normalized
+}
+
+function RunErrorInline({ message }: { message: string }): React.ReactElement {
   return (
-    <details className={styles.errorDetails}>
-      <summary>
-        <Text size={1} tone="danger" className={styles.errorSummaryText}>
-          ✗ {summary}
-          {isTruncated ? `…` : ``}
-        </Text>
-      </summary>
-      <pre className={styles.errorPre}>{message}</pre>
-    </details>
+    <Text size={1} tone="danger" truncate>
+      ✗ {message}
+    </Text>
+  )
+}
+
+function RunErrorCard({ message }: { message: string }): React.ReactElement {
+  return (
+    <InlineEventCard
+      icon={CircleAlert}
+      title="run error"
+      summary={runErrorSummary(message)}
+      defaultExpanded={false}
+      headerSurface
+    >
+      <pre className={toolBlock.codeBlock}>{message}</pre>
+    </InlineEventCard>
   )
 }
 
@@ -550,6 +558,10 @@ export const AgentResponseLive = memo(function AgentResponseLive({
         )
       })}
 
+      {failureText && isLongRunError(failureText) && (
+        <RunErrorCard message={failureText} />
+      )}
+
       <Stack align="center" gap={2} className={styles.metaRow}>
         {showThinking && <ThinkingIndicator />}
         {done && (
@@ -559,7 +571,9 @@ export const AgentResponseLive = memo(function AgentResponseLive({
               : `✓ done`}
           </Text>
         )}
-        {failureText && <RunErrorMessage message={failureText} />}
+        {failureText && !isLongRunError(failureText) && (
+          <RunErrorInline message={failureText} />
+        )}
         {/* Elapsed-time ticker — visible while the response is still
             in flight so the user can see how long the model has been
             working ("Thinking · 12s", or just "12s" once tokens are
@@ -764,6 +778,10 @@ export const AgentResponse = memo(function AgentResponse({
         return <ToolCallView key={item.toolCallId} item={item} />
       })}
 
+      {section.error && isLongRunError(section.error) && (
+        <RunErrorCard message={section.error} />
+      )}
+
       <Stack align="center" gap={2} className={styles.metaRow}>
         {showThinking && <ThinkingIndicator />}
         {section.done && (
@@ -773,7 +791,9 @@ export const AgentResponse = memo(function AgentResponse({
               : `✓ done`}
           </Text>
         )}
-        {section.error && <RunErrorMessage message={section.error} />}
+        {section.error && !isLongRunError(section.error) && (
+          <RunErrorInline message={section.error} />
+        )}
         {/* Elapsed-time ticker — kept in sync with the live variant
             above so cached sections (rare during streaming, but the
             type permits it) render the same meta row. */}