4 files changed, 70 insertions, 14 deletions
diff --git a/packages/ui/src/components/message-part.css b/packages/ui/src/components/message-part.css
index 58227f625..6727bb22f 100644
--- a/packages/ui/src/components/message-part.css
+++ b/packages/ui/src/components/message-part.css
@@ -225,6 +225,33 @@
   }
 }
 
+[data-component="compaction-part"] {
+  width: 100%;
+  display: flex;
+  flex-direction: column;
+  align-items: stretch;
+
+  [data-slot="compaction-part-divider"] {
+    display: flex;
+    align-items: center;
+    gap: 12px;
+    padding: 10px 0;
+    width: 100%;
+  }
+
+  [data-slot="compaction-part-line"] {
+    flex: 1 1 auto;
+    height: 1px;
+    background: var(--border-weak-base);
+  }
+
+  [data-slot="compaction-part-label"] {
+    flex: 0 0 auto;
+    white-space: nowrap;
+    text-align: center;
+  }
+}
+
 [data-component="reasoning-part"] {
   width: 100%;
   color: var(--text-base);
diff --git a/packages/ui/src/components/message-part.tsx b/packages/ui/src/components/message-part.tsx
index 6b6dfe2e5..02a99f9dd 100644
--- a/packages/ui/src/components/message-part.tsx
+++ b/packages/ui/src/components/message-part.tsx
@@ -1037,6 +1037,21 @@ PART_MAPPING["tool"] = function ToolPartDisplay(props) {
   )
 }
 
+PART_MAPPING["compaction"] = function CompactionPartDisplay() {
+  const i18n = useI18n()
+  return (
+    <div data-component="compaction-part">
+      <div data-slot="compaction-part-divider">
+        <span data-slot="compaction-part-line" />
+        <span data-slot="compaction-part-label" class="text-12-regular text-text-weak">
+          {i18n.t("ui.messagePart.compaction")}
+        </span>
+        <span data-slot="compaction-part-line" />
+      </div>
+    </div>
+  )
+}
+
 PART_MAPPING["text"] = function TextPartDisplay(props) {
   const data = useData()
   const i18n = useI18n()
diff --git a/packages/ui/src/components/session-turn.css b/packages/ui/src/components/session-turn.css
index 9639e6635..4af87b361 100644
--- a/packages/ui/src/components/session-turn.css
+++ b/packages/ui/src/components/session-turn.css
@@ -37,6 +37,12 @@
     max-width: 100%;
   }
 
+  [data-slot="session-turn-compaction"] {
+    width: 100%;
+    min-width: 0;
+    align-self: stretch;
+  }
+
   [data-slot="session-turn-thinking"] {
     display: flex;
     align-items: center;
diff --git a/packages/ui/src/components/session-turn.tsx b/packages/ui/src/components/session-turn.tsx
index bd4f2843a..e329b1170 100644
--- a/packages/ui/src/components/session-turn.tsx
+++ b/packages/ui/src/components/session-turn.tsx
@@ -6,7 +6,7 @@ import { Binary } from "@opencode-ai/util/binary"
 import { getDirectory, getFilename } from "@opencode-ai/util/path"
 import { createEffect, createMemo, createSignal, For, on, ParentProps, Show } from "solid-js"
 import { Dynamic } from "solid-js/web"
-import { AssistantParts, Message, PART_MAPPING } from "./message-part"
+import { AssistantParts, Message, Part, PART_MAPPING } from "./message-part"
 import { Card } from "./card"
 import { Accordion } from "./accordion"
 import { StickyAccordionHeader } from "./sticky-accordion-header"
@@ -139,7 +139,6 @@ export function SessionTurn(
   props: ParentProps<{
     sessionID: string
     messageID: string
-    lastUserMessageID?: string
     showReasoningSummaries?: boolean
     shellToolDefaultOpen?: boolean
     editToolDefaultOpen?: boolean
@@ -187,18 +186,18 @@ export function SessionTurn(
     return msg
   })
 
-  const lastUserMessageID = createMemo(() => {
-    if (props.lastUserMessageID) return props.lastUserMessageID
-
+  const pending = createMemo(() => {
     const messages = allMessages() ?? emptyMessages
-    for (let i = messages.length - 1; i >= 0; i--) {
-      const msg = messages[i]
-      if (msg?.role === "user") return msg.id
-    }
-    return undefined
+    return messages.findLast(
+      (item): item is AssistantMessage => item.role === "assistant" && typeof item.time.completed !== "number",
+    )
+  })
+  const active = createMemo(() => {
+    const msg = message()
+    const item = pending()
+    if (!msg || !item) return false
+    return item.parentID === msg.id
   })
-
-  const isLastUserMessage = createMemo(() => props.messageID === lastUserMessageID())
 
   const parts = createMemo(() => {
     const msg = message()
@@ -206,6 +205,8 @@ export function SessionTurn(
     return list(data.store.part?.[msg.id], emptyParts)
   })
 
+  const compaction = createMemo(() => parts().find((part) => part.type === "compaction"))
+
   const diffs = createMemo(() => {
     const files = message()?.summary?.diffs
     if (!files?.length) return emptyDiffs
@@ -285,7 +286,7 @@ export function SessionTurn(
   })
 
   const status = createMemo(() => data.store.session_status[props.sessionID] ?? idle)
-  const working = createMemo(() => status().type !== "idle" && isLastUserMessage())
+  const working = createMemo(() => status().type !== "idle" && active())
   const showReasoningSummaries = createMemo(() => props.showReasoningSummaries ?? true)
 
   const assistantCopyPartID = createMemo(() => {
@@ -365,6 +366,13 @@ export function SessionTurn(
                 <div data-slot="session-turn-message-content" aria-live="off">
                   <Message message={msg()} parts={parts()} interrupted={interrupted()} />
                 </div>
+                <Show when={compaction()}>
+                  {(part) => (
+                    <div data-slot="session-turn-compaction">
+                      <Part part={part()} message={msg()} hideDetails />
+                    </div>
+                  )}
+                </Show>
                 <Show when={assistantMessages().length > 0}>
                   <div data-slot="session-turn-assistant-content" aria-hidden={working()}>
                     <AssistantParts
@@ -386,7 +394,7 @@ export function SessionTurn(
                     </Show>
                   </div>
                 </Show>
-                <SessionRetry status={status()} show={isLastUserMessage()} />
+                <SessionRetry status={status()} show={active()} />
                 <Show when={edited() > 0 && !working()}>
                   <div data-slot="session-turn-diffs">
                     <Collapsible open={open()} onOpenChange={setOpen} variant="ghost">