diff --git a/src/lib/opencode-session-state.ts b/src/lib/opencode-session-state.ts
index 09e5765..9422b14 100644
--- a/src/lib/opencode-session-state.ts
+++ b/src/lib/opencode-session-state.ts
@@ -674,8 +674,18 @@ export function hydrateOpenCodeSession(
   const snapshotOrder = [...next.compactionOrder];
   snapshotOrder.forEach((id, index) => {
     const snapshotEvent = next.compactionsById[id];
-    const existingID = snapshotEvent.nativePartID
-      ? findCompactionId(current ?? state, { nativePartID: snapshotEvent.nativePartID })
+    const existingID = current
+      ? findCompactionId(current, { id: snapshotEvent.id })
+        ?? (snapshotEvent.nativePartID
+          ? findCompactionId(current, { nativePartID: snapshotEvent.nativePartID })
+          : undefined)
+        ?? (snapshotEvent.anchorPartID
+          ? [...current.compactionOrder].reverse().find((candidateID) => {
+              const candidate = current.compactionsById[candidateID];
+              return candidate?.anchorPartID === snapshotEvent.anchorPartID
+                && candidate.anchorMessageID === snapshotEvent.anchorMessageID;
+            })
+          : undefined)
       : undefined;
     const pendingID = !existingID && snapshotEvent.source === 'manual'
       ? [...(current?.compactionOrder ?? [])].reverse().find((candidateID) => {
@@ -694,10 +704,10 @@ export function hydrateOpenCodeSession(
     const preservedID = existingID ?? pendingID;
     const existing = preservedID ? current?.compactionsById[preservedID] : undefined;
     const idToUse = preservedID ?? id;
-    const isLatestActive = status !== 'idle' && index === snapshotOrder.length - 1;
     const completed = existing?.status === 'completed'
       || snapshotEvent.completedAt !== undefined
-      || !isLatestActive;
+      || status === 'idle'
+      || existing?.status !== 'running';
     if (idToUse !== id) {
       const compactionsById = { ...next.compactionsById };
       delete compactionsById[id];
diff --git a/src/stores/opencode.ts b/src/stores/opencode.ts
index affbb1c..8a7dc0d 100644
--- a/src/stores/opencode.ts
+++ b/src/stores/opencode.ts
@@ -2390,6 +2390,7 @@ function finishSessionRunSuccessfully(
   runToken: number,
   messages: RawMessage[],
   statuses: Record<string, OpencodeSessionStatus> = {},
+  compactionGeneration?: number,
 ): boolean {
   if (!isSessionRunCurrent(sessionId, runToken)) return false;
   flushSessionRunStreamBatch(set, sessionId, runToken);
@@ -2397,6 +2398,19 @@ function finishSessionRunSuccessfully(
   set((state) => {
     const sendingSessionIds = withoutKey(state.sendingSessionIds, sessionId);
     const nextState = { ...state, sendingSessionIds };
+    const currentTranscript = state.sessionTranscriptBySessionId[sessionId];
+    const completedTranscript = compactionGeneration !== undefined
+      && state.runtimeGeneration === compactionGeneration
+      ? completeCompaction(
+          getOrCreateSessionTranscript(state, sessionId),
+          { runID: String(runToken), generation: compactionGeneration },
+          {
+            runID: String(runToken),
+            generation: compactionGeneration,
+            completedAt: Date.now(),
+          },
+        )
+      : currentTranscript;
     return {
       ...getSessionMessagePatch(state, sessionId, messages),
       ...dispatchSessionRunEvent(state, sessionId, {
@@ -2413,6 +2427,14 @@ function finishSessionRunSuccessfully(
       sendingSessionId: getSendingSessionIdForSelection(nextState),
       loading: false,
       ...errorState(null),
+      ...(completedTranscript && completedTranscript !== currentTranscript
+        ? {
+            sessionTranscriptBySessionId: {
+              ...state.sessionTranscriptBySessionId,
+              [sessionId]: completedTranscript,
+            },
+          }
+        : {}),
     };
   });
   invalidateSessionRun(sessionId);
@@ -3051,6 +3073,7 @@ async function runSessionSubmission(
           runToken,
           messages,
           statuses,
+          submission.kind === 'compact' ? runGeneration : undefined,
         );
         if (
           completed
diff --git a/tests/unit/opencode-session-state.test.ts b/tests/unit/opencode-session-state.test.ts
index 9724294..5214ac9 100644
--- a/tests/unit/opencode-session-state.test.ts
+++ b/tests/unit/opencode-session-state.test.ts
@@ -204,7 +204,7 @@ describe('OpenCode native session state', () => {
     ]);
   });
 
-  it('allows only the latest compaction in an active snapshot to remain running', () => {
+  it('hydrates cold compaction snapshots as completed even while the session is busy', () => {
     const state = hydrateOpenCodeSession('ses_1', [{
       info: { id: 'msg_1', role: 'assistant', sessionID: 'ses_1' },
       parts: [
@@ -214,7 +214,50 @@ describe('OpenCode native session state', () => {
     }], 'busy');
 
     expect(getOrderedSessionCompactions(state).map((event) => event.status))
-      .toEqual(['completed', 'running']);
+      .toEqual(['completed', 'completed']);
+  });
+
+  it('does not attach a historical compaction to a later ordinary busy run', () => {
+    const current = hydrateOpenCodeSession('ses_1', [{
+      info: { id: 'msg_2', role: 'user', sessionID: 'ses_1' },
+      parts: [{ id: 'text_2', type: 'text', text: 'continue normally' }],
+    }], 'busy');
+    const state = hydrateOpenCodeSession('ses_1', [
+      {
+        info: { id: 'msg_1', role: 'assistant', sessionID: 'ses_1' },
+        parts: [{ id: 'compact_1', type: 'compaction', auto: true }],
+      },
+      {
+        info: { id: 'msg_2', role: 'user', sessionID: 'ses_1' },
+        parts: [{ id: 'text_2', type: 'text', text: 'continue normally' }],
+      },
+    ], 'busy', current);
+
+    expect(getOrderedSessionCompactions(state)).toEqual([
+      expect.objectContaining({ nativePartID: 'compact_1', status: 'completed' }),
+    ]);
+  });
+
+  it('keeps a matching real-time native compaction running during active hydration', () => {
+    const current = reduceOpenCodeEvent(
+      hydrateOpenCodeSession('ses_1', [], 'busy'),
+      {
+        type: 'message.part.updated',
+        payload: {
+          sessionID: 'ses_1',
+          messageID: 'msg_1',
+          part: { id: 'compact_1', type: 'compaction', auto: true },
+        },
+      },
+    );
+    const state = hydrateOpenCodeSession('ses_1', [{
+      info: { id: 'msg_1', role: 'assistant', sessionID: 'ses_1' },
+      parts: [{ id: 'compact_1', type: 'compaction', auto: true }],
+    }], 'busy', current);
+
+    expect(getOrderedSessionCompactions(state)).toEqual([
+      expect.objectContaining({ nativePartID: 'compact_1', status: 'running' }),
+    ]);
   });
 
   it('does not downgrade a completed compaction during busy history hydration', () => {
diff --git a/tests/unit/opencode-store.test.ts b/tests/unit/opencode-store.test.ts
index 8ec16a9..cf6dd77 100644
--- a/tests/unit/opencode-store.test.ts
+++ b/tests/unit/opencode-store.test.ts
@@ -4995,6 +4995,90 @@ describe('opencode store', () => {
     expect(compactOutcome).toBe('resolved');
   });
 
+  it('completes compact and releases its queued prompt from HTTP idle without lifecycle SSE', async () => {
+    vi.useFakeTimers();
+    try {
+      createHostEventSourceMock
+        .mockReturnValueOnce(new MockEventSource('/api/opencode/events?sessionId=ses_compact_http_idle'))
+        .mockReturnValueOnce(new MockEventSource('/api/opencode/events?sessionId=ses_compact_http_idle'));
+      let statusPolls = 0;
+      let promptPosted = false;
+      useOpencodeStore.setState({
+        runtimeGeneration: 11,
+        selectedSessionId: 'ses_compact_http_idle',
+        sessions: [{ id: 'ses_compact_http_idle' }],
+        sessionStatuses: { ses_compact_http_idle: { type: 'idle' } },
+      });
+      hostApiFetchMock.mockImplementation(async (path: string, init?: RequestInit) => {
+        if (path.endsWith('/summarize') && init?.method === 'POST') return { success: true };
+        if (path.endsWith('/messages') && init?.method === 'POST') {
+          promptPosted = true;
+          return { success: true };
+        }
+        if (path === '/api/opencode/sessions/status') {
+          statusPolls += 1;
+          return {
+            statuses: {
+              ses_compact_http_idle: {
+                type: statusPolls === 1 ? 'busy' : 'idle',
+              },
+            },
+          };
+        }
+        if (path.endsWith('/messages')) {
+          return {
+            messages: promptPosted
+              ? [
+                  { id: 'msg_http_user', role: 'user', content: 'After HTTP idle' },
+                  { id: 'msg_http_assistant', role: 'assistant', content: 'Queued prompt done' },
+                ]
+              : [],
+          };
+        }
+        throw new Error(`Unexpected request: ${path}`);
+      });
+
+      const compacting = useOpencodeStore.getState().compactSession('ses_compact_http_idle');
+      await vi.waitFor(() => {
+        const transcript = useOpencodeStore.getState()
+          .sessionTranscriptBySessionId.ses_compact_http_idle;
+        expect(transcript?.compactionsById[transcript.compactionOrder[0]!]).toMatchObject({
+          status: 'running',
+          source: 'manual',
+          generation: 11,
+        });
+      });
+      await useOpencodeStore.getState().sendSessionMessage(
+        'ses_compact_http_idle',
+        'After HTTP idle',
+      );
+      expect(promptPosted).toBe(false);
+      expect(useOpencodeStore.getState().queuedSessionPrompts.ses_compact_http_idle)
+        .toHaveLength(1);
+
+      await vi.advanceTimersByTimeAsync(750);
+      await compacting;
+      await vi.waitFor(() => expect(promptPosted).toBe(true));
+
+      const transcript = useOpencodeStore.getState()
+        .sessionTranscriptBySessionId.ses_compact_http_idle!;
+      expect(transcript.compactionsById[transcript.compactionOrder[0]!]).toMatchObject({
+        status: 'completed',
+        source: 'manual',
+        generation: 11,
+        completedAt: expect.any(Number),
+      });
+      expect(useOpencodeStore.getState().queuedSessionPrompts.ses_compact_http_idle)
+        .toBeUndefined();
+      await vi.waitFor(() => {
+        expect(useOpencodeStore.getState().sendingSessionIds.ses_compact_http_idle)
+          .toBeUndefined();
+      });
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
   it('removes an unfinished manual compaction when its POST fails', async () => {
     const post = createDeferred<{ success: boolean }>();
     createHostEventSourceMock.mockReturnValue(