diff --git a/packages/tui/src/component/prompt/index.tsx b/packages/tui/src/component/prompt/index.tsx
index 9fad2eb21c81..6021d06b37e5 100644
--- a/packages/tui/src/component/prompt/index.tsx
+++ b/packages/tui/src/component/prompt/index.tsx
@@ -160,6 +160,7 @@ export function Prompt(props: PromptProps) {
   const dialog = useDialog()
   const toast = useToast()
   const status = createMemo(() => data.session.status(props.sessionID ?? ""))
+  const compaction = createMemo(() => data.session.compaction.get(props.sessionID ?? ""))
   const activeSubagents = createMemo(() => {
     if (!props.sessionID) return 0
     return data.session.family(props.sessionID).filter(
@@ -1637,6 +1638,18 @@ export function Prompt(props: PromptProps) {
         </box>
         <box width="100%" flexDirection="row" justifyContent="space-between">
           <Switch>
+            <Match when={compaction()}>
+              <box flexDirection="row" gap={1} flexGrow={1} justifyContent="flex-start">
+                <box marginLeft={1}>
+                  <Spinner>Compacting conversation...</Spinner>
+                </box>
+                <Show when={compaction() === "auto"}>
+                  <text fg={theme.text}>
+                    esc <span style={{ fg: theme.textMuted }}>interrupt</span>
+                  </text>
+                </Show>
+              </box>
+            </Match>
             <Match when={status() === "running"}>
               <box flexDirection="row" gap={1} flexGrow={1} justifyContent="flex-start">
                 <box marginLeft={1}>
diff --git a/packages/tui/src/context/data.tsx b/packages/tui/src/context/data.tsx
index 0ed464e561a6..8db1e2f6b9aa 100644
--- a/packages/tui/src/context/data.tsx
+++ b/packages/tui/src/context/data.tsx
@@ -20,12 +20,13 @@ import type {
   SkillV2Info,
   V2Event,
 } from "@opencode-ai/sdk/v2"
-import { createStore, produce } from "solid-js/store"
+import { createStore, produce, reconcile } from "solid-js/store"
 import { createSimpleContext } from "./helper"
 import { useSDK } from "./sdk"
 import { createSignal, onCleanup } from "solid-js"
 
 export type DataSessionStatus = "idle" | "running"
+type CompactionReason = Extract<V2Event, { type: "session.compaction.started" }>["data"]["reason"]
 
 const messageIDFromEvent = (eventID: string) => eventID.replace(/^evt_/, "msg_")
 
@@ -51,6 +52,7 @@ type Data = {
     // session ID in that family, including the key itself once its info arrives.
     family: Record<string, string[]>
     status: Record<string, DataSessionStatus>
+    compaction: Record<string, CompactionReason>
     message: Record<string, SessionMessage[]>
     permission: Record<string, PermissionV2Request[]>
     question: Record<string, QuestionV2Request[]>
@@ -85,6 +87,7 @@ export const { use: useData, provider: DataProvider } = createSimpleContext({
         info: {},
         family: {},
         status: {},
+        compaction: {},
         message: {},
         permission: {},
         question: {},
@@ -200,6 +203,25 @@ export const { use: useData, provider: DataProvider } = createSimpleContext({
       )
     }
 
+    const startCompaction = (sessionID: string, reason: CompactionReason) => {
+      if (store.session.status[sessionID] !== "running") setStore("session", "status", sessionID, "running")
+      if (store.session.compaction[sessionID] !== reason)
+        setStore("session", "compaction", sessionID, reason)
+    }
+
+    const clearCompaction = (sessionID: string, settleManual = true) => {
+      const reason = store.session.compaction[sessionID]
+      if (!reason) return
+      setStore(
+        "session",
+        "compaction",
+        produce((draft) => {
+          delete draft[sessionID]
+        }),
+      )
+      if (settleManual && reason === "manual") setStore("session", "status", sessionID, "idle")
+    }
+
     function handleEvent(event: V2Event) {
       switch (event.type) {
         case "session.created":
@@ -321,6 +343,7 @@ export const { use: useData, provider: DataProvider } = createSimpleContext({
           })
           break
         case "session.step.started":
+          clearCompaction(event.data.sessionID, false)
           setStore("session", "status", event.data.sessionID, "running")
           message.update(event.data.sessionID, (draft, index) => {
             if (index.has(event.data.assistantMessageID)) return
@@ -517,11 +540,14 @@ export const { use: useData, provider: DataProvider } = createSimpleContext({
           })
           break
         case "session.retried":
-        case "session.compaction.started":
           setStore("session", "status", event.data.sessionID, "running")
           break
+        case "session.compaction.started":
+          startCompaction(event.data.sessionID, event.data.reason)
+          break
         case "session.execution.settled":
           setStore("session", "status", event.data.sessionID, "idle")
+          clearCompaction(event.data.sessionID, false)
           break
         case "session.revert.staged":
           if (store.session.info[event.data.sessionID])
@@ -535,6 +561,7 @@ export const { use: useData, provider: DataProvider } = createSimpleContext({
         case "session.compaction.delta":
           break
         case "session.compaction.ended":
+          clearCompaction(event.data.sessionID)
           message.update(event.data.sessionID, (draft, index) => {
             message.append(draft, index, {
               id: messageIDFromEvent(event.id),
@@ -655,6 +682,17 @@ export const { use: useData, provider: DataProvider } = createSimpleContext({
         status(sessionID: string) {
           return store.session.status[sessionID] ?? "idle"
         },
+        compaction: {
+          get(sessionID: string) {
+            return store.session.compaction[sessionID]
+          },
+          startManual(sessionID: string) {
+            startCompaction(sessionID, "manual")
+          },
+          clearManual(sessionID: string) {
+            if (store.session.compaction[sessionID] === "manual") clearCompaction(sessionID)
+          },
+        },
         async refresh(sessionID: string) {
           setStore("session", "info", sessionID, mutable(await sdk.api.session.get({ sessionID })))
           registerSession(sessionID)
@@ -840,6 +878,7 @@ export const { use: useData, provider: DataProvider } = createSimpleContext({
 
     async function bootstrap() {
       if (bootstrapping) return bootstrapping
+      setStore("session", "compaction", reconcile({}))
       bootstrapping = Promise.allSettled([
         sdk.api.session
           .list({
diff --git a/packages/tui/src/routes/session/index.tsx b/packages/tui/src/routes/session/index.tsx
index b968f13cd338..c7f757316def 100644
--- a/packages/tui/src/routes/session/index.tsx
+++ b/packages/tui/src/routes/session/index.tsx
@@ -382,7 +382,25 @@ export function Session() {
         aliases: ["summarize"],
       },
       run: () => {
-        void sdk.api.session.compact({ sessionID: route.sessionID })
+        const sessionID = route.sessionID
+        if (data.session.status(sessionID) === "running") {
+          toast.show({
+            variant: "warning",
+            title: "Compaction unavailable",
+            message: "Wait for the current session activity to finish.",
+          })
+          dialog.clear()
+          return
+        }
+        data.session.compaction.startManual(sessionID)
+        void sdk.api.session.compact({ sessionID }).catch((error) => {
+          data.session.compaction.clearManual(sessionID)
+          toast.show({
+            variant: "error",
+            title: "Compaction failed",
+            message: errorMessage(error),
+          })
+        })
         dialog.clear()
       },
     },
diff --git a/packages/tui/test/cli/tui/data.test.tsx b/packages/tui/test/cli/tui/data.test.tsx
index 0587662dc367..66b845530aa6 100644
--- a/packages/tui/test/cli/tui/data.test.tsx
+++ b/packages/tui/test/cli/tui/data.test.tsx
@@ -310,6 +310,61 @@ test("tracks session status from active sessions and execution events", async ()
     })
     await wait(() => data.session.status("session-live") === "idle")
 
+    emitEvent(events, {
+      id: "evt_compaction_started",
+      created: 0,
+      type: "session.compaction.started",
+      durable: durable("session-compact"),
+      data: {
+        sessionID: "session-compact",
+        reason: "manual",
+      },
+    })
+    await wait(() => data.session.compaction.get("session-compact") === "manual")
+    expect(data.session.status("session-compact")).toBe("running")
+
+    emitEvent(events, {
+      id: "evt_compaction_ended",
+      created: 0,
+      type: "session.compaction.ended",
+      durable: durable("session-compact", 1, 2),
+      data: {
+        sessionID: "session-compact",
+        reason: "manual",
+        text: "Summary",
+        recent: "",
+      },
+    })
+    await wait(() => data.session.compaction.get("session-compact") === undefined)
+    expect(data.session.status("session-compact")).toBe("idle")
+
+    emitEvent(events, {
+      id: "evt_auto_compaction_started",
+      created: 0,
+      type: "session.compaction.started",
+      durable: durable("session-auto-compact"),
+      data: {
+        sessionID: "session-auto-compact",
+        reason: "auto",
+      },
+    })
+    await wait(() => data.session.compaction.get("session-auto-compact") === "auto")
+
+    emitEvent(events, {
+      id: "evt_post_compaction_step",
+      created: 0,
+      type: "session.step.started",
+      durable: durable("session-auto-compact", 1, 2),
+      data: {
+        sessionID: "session-auto-compact",
+        assistantMessageID: "message-after-compaction",
+        agent: "build",
+        model: { id: "model", providerID: "provider" },
+      },
+    })
+    await wait(() => data.session.compaction.get("session-auto-compact") === undefined)
+    expect(data.session.status("session-auto-compact")).toBe("running")
+
     emitEvent(events, {
       id: "evt_failed_step_started",
       created: 0,