fix(gateway): let Desktop omit duplicate transcripts on session resume (salvage #69926)

apps/desktop/src/app/contrib/hooks/use-session-tile-delegate.test.ts

@@ -77,7 +77,8 @@ describe('useSessionTileDelegate resumeTile', () => {
     expect(requestGateway).toHaveBeenCalledWith('session.resume', {
       session_id: 'stored-x',
       cols: 96,
-      profile: 'ai-engineer'
+      profile: 'ai-engineer',
+      omit_messages: true
     })
   })
 
@@ -94,7 +95,8 @@ describe('useSessionTileDelegate resumeTile', () => {
     expect(requestGateway).toHaveBeenCalledWith('session.resume', {
       session_id: 'stored-y',
       cols: 96,
-      profile: 'default'
+      profile: 'default',
+      omit_messages: true
     })
   })
 })

apps/desktop/src/app/contrib/hooks/use-session-tile-delegate.ts

@@ -79,6 +79,7 @@ export function useSessionTileDelegate({
           requestGateway<SessionResumeResponse>('session.resume', {
             session_id: storedSessionId,
             cols: 96,
+            omit_messages: true,
             ...(profile ? { profile } : {})
           })
         ])

apps/desktop/src/app/session/hooks/use-prompt-actions/index.test.tsx

@@ -1797,7 +1797,8 @@ describe('usePromptActions submit / queue drain semantics', () => {
     expect(accepted).toBe(true)
     expect(requestGateway).toHaveBeenCalledWith('session.resume', {
       session_id: 'stored-session-b',
-      source: 'desktop'
+      source: 'desktop',
+      omit_messages: true
     })
     expect(requestGateway).toHaveBeenCalledWith(
       'prompt.submit',
@@ -1933,7 +1934,8 @@ describe('usePromptActions submit / queue drain semantics', () => {
     // Must resume the correct stored session to get the right runtime id.
     expect(requestGateway).toHaveBeenCalledWith('session.resume', {
       session_id: 'stored-session-a',
-      source: 'desktop'
+      source: 'desktop',
+      omit_messages: true
     })
     // The prompt must land in the resumed session, NOT the foreground.
     expect(requestGateway).toHaveBeenCalledWith(
@@ -2194,7 +2196,7 @@ describe('usePromptActions redirectPrompt', () => {
     expect(await handle!.redirectPrompt('reconnect nudge')).toBe(true)
     expect(calls.map(c => c.method)).toEqual(['session.redirect', 'session.resume', 'session.redirect'])
     expect(calls[0]?.params).toEqual({ session_id: RUNTIME_SESSION_ID, text: 'reconnect nudge' })
-    expect(calls[1]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop' })
+    expect(calls[1]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop', omit_messages: true })
     expect(calls[2]?.params).toEqual({ session_id: RECOVERED_SESSION_ID, text: 'reconnect nudge' })
     expect(handle!.activeSessionIdRef.current).toBe(RECOVERED_SESSION_ID)
   })
@@ -2735,7 +2737,7 @@ describe('usePromptActions sleep/wake session recovery', () => {
     expect(ok).toBe(true)
     // First submit (stale id) → session.resume (stored id) → retry submit (fresh id).
     expect(calls.map(c => c.method)).toEqual(['prompt.submit', 'session.resume', 'prompt.submit'])
-    expect(calls[1]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop' })
+    expect(calls[1]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop', omit_messages: true })
     expect(calls[2]?.params).toEqual({ session_id: RECOVERED_SESSION_ID, text: 'message after wake' })
   })
 
@@ -2779,7 +2781,12 @@ describe('usePromptActions sleep/wake session recovery', () => {
     )
 
     expect(await handle!.submitText('message after wake')).toBe(true)
-    expect(calls[1]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop', profile: 'work' })
+    expect(calls[1]?.params).toEqual({
+      session_id: STORED_SESSION_ID,
+      source: 'desktop',
+      omit_messages: true,
+      profile: 'work'
+    })
 
     setSessions(() => [])
   })
@@ -2826,7 +2833,12 @@ describe('usePromptActions sleep/wake session recovery', () => {
     )
 
     expect(await handle!.submitText('message after wake')).toBe(true)
-    expect(calls[1]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop', profile: 'work' })
+    expect(calls[1]?.params).toEqual({
+      session_id: STORED_SESSION_ID,
+      source: 'desktop',
+      omit_messages: true,
+      profile: 'work'
+    })
 
     vi.mocked(getSession).mockReset()
     setSessions(() => [])
@@ -2887,7 +2899,11 @@ describe('usePromptActions sleep/wake session recovery', () => {
       session_id: 'rt-background-stale',
       text: 'queued background message after wake'
     })
-    expect(calls[1]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop' })
+    expect(calls[1]?.params).toEqual({
+      session_id: STORED_SESSION_ID,
+      source: 'desktop',
+      omit_messages: true
+    })
     expect(calls[2]?.params).toEqual({
       queued: true,
       session_id: RECOVERED_SESSION_ID,
@@ -2935,7 +2951,11 @@ describe('usePromptActions sleep/wake session recovery', () => {
 
     expect(calls.map(c => c.method)).toEqual(['session.interrupt', 'session.resume', 'session.interrupt'])
     expect(calls[0]?.params).toEqual({ session_id: RUNTIME_SESSION_ID })
-    expect(calls[1]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop' })
+    expect(calls[1]?.params).toEqual({
+      session_id: STORED_SESSION_ID,
+      source: 'desktop',
+      omit_messages: true
+    })
     expect(calls[2]?.params).toEqual({ session_id: RECOVERED_SESSION_ID })
   })
 
@@ -3067,7 +3087,11 @@ describe('usePromptActions sleep/wake session recovery', () => {
 
     expect(ok).toBe(true)
     expect(calls.map(c => c.method)).toEqual(['prompt.submit', 'session.resume', 'prompt.submit'])
-    expect(calls[1]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop' })
+    expect(calls[1]?.params).toEqual({
+      session_id: STORED_SESSION_ID,
+      source: 'desktop',
+      omit_messages: true
+    })
     expect(calls[2]?.params).toEqual({
       session_id: RECOVERED_SESSION_ID,
       text: 'message during starved loop'
@@ -3110,7 +3134,11 @@ describe('usePromptActions sleep/wake session recovery', () => {
     expect(ok).toBe(true)
     expect(createBackendSessionForSend).not.toHaveBeenCalled()
     expect(calls.map(c => c.method)).toEqual(['session.resume', 'prompt.submit'])
-    expect(calls[0]?.params).toEqual({ session_id: STORED_SESSION_ID, source: 'desktop' })
+    expect(calls[0]?.params).toEqual({
+      session_id: STORED_SESSION_ID,
+      source: 'desktop',
+      omit_messages: true
+    })
     expect(calls[1]?.params).toMatchObject({ session_id: RECOVERED_SESSION_ID })
   })
 
@@ -3421,7 +3449,8 @@ describe('usePromptActions submit session-context isolation (#54527)', () => {
     expect(calls.some(c => c.method === 'prompt.submit')).toBe(false)
     expect(calls.find(c => c.method === 'session.resume')?.params).toEqual({
       session_id: STORED_SESSION_A,
-      source: 'desktop'
+      source: 'desktop',
+      omit_messages: true
     })
   })
 

apps/desktop/src/app/session/hooks/use-prompt-actions/index.ts

@@ -639,6 +639,7 @@ export function usePromptActions({
           const resumed = await requestGateway<{ session_id: string }>('session.resume', {
             session_id: selectedStoredSessionIdRef.current,
             source: 'desktop',
+            omit_messages: true,
             ...(resumeProfile ? { profile: resumeProfile } : {})
           })
 
@@ -744,6 +745,7 @@ export function usePromptActions({
             const resumed = await requestGateway<{ session_id: string }>('session.resume', {
               session_id: selectedStoredSessionIdRef.current,
               source: 'desktop',
+              omit_messages: true,
               ...(resumeProfile ? { profile: resumeProfile } : {})
             })
 

apps/desktop/src/app/session/hooks/use-prompt-actions/submit.ts

@@ -484,6 +484,7 @@ export function useSubmitPrompt(deps: SubmitPromptDeps) {
           const resumed = await requestGateway<{ session_id: string }>('session.resume', {
             session_id: targetStoredSessionId,
             source: 'desktop',
+            omit_messages: true,
             ...(resumeProfile ? { profile: resumeProfile } : {})
           })
 
@@ -637,6 +638,7 @@ export function useSubmitPrompt(deps: SubmitPromptDeps) {
             const resumed = await requestGateway<{ session_id: string }>('session.resume', {
               session_id: recoverStoredSessionId,
               source: 'desktop',
+              omit_messages: true,
               ...(resumeProfile ? { profile: resumeProfile } : {})
             })
 

apps/desktop/src/app/session/hooks/use-session-actions.test.tsx

@@ -896,7 +896,7 @@ describe('resumeSession failure recovery', () => {
 
     expect(resumeParams).not.toHaveProperty('lazy')
     expect(resumeParams).not.toHaveProperty('eager_build')
-    expect(resumeParams).toMatchObject({ source: 'desktop' })
+    expect(resumeParams).toMatchObject({ source: 'desktop', omit_messages: true })
   })
 
   it('arms the failure latch when resume succeeds with an empty transcript for a non-empty stored session', async () => {
@@ -1431,6 +1431,10 @@ describe('resumeSession warm-cache mapping integrity', () => {
     expect(methods).toContain('session.activate')
     expect(methods).not.toContain('session.resume')
     expect(getSessionMessages).toHaveBeenCalledWith('stored-A', undefined)
+    expect(requestGateway).toHaveBeenCalledWith(
+      'session.activate',
+      expect.objectContaining({ omit_messages: true, session_id: 'rt-A' })
+    )
     expect(runtimeIdByStoredSessionIdRef.current.get('stored-A')).toBe('rt-A')
   })
 

apps/desktop/src/app/session/hooks/use-session-actions/index.ts

@@ -700,7 +700,8 @@ export function useSessionActions({
             try {
               activated = await requestGateway<SessionResumeResponse>('session.activate', {
                 session_id: cachedRuntimeId,
-                cols: 96
+                cols: 96,
+                omit_messages: true
               })
             } catch (error) {
               // Compatibility for older backends. Modern backends require
@@ -866,12 +867,14 @@ export function useSessionActions({
           session_id: storedSessionId,
           cols: 96,
           source: 'desktop',
+          // REST is the transcript authority for Desktop. Avoid duplicating a
+          // potentially huge compression lineage in the WebSocket response.
           // Watch windows attach lazily (live mirror). Every other cold resume
           // gets the gateway's default deferred build: the RPC returns the
           // transcript immediately instead of blocking the switch on _make_agent
           // (MCP discovery / prompt build), and the agent pre-warms in the
           // background while the prefetch above paints the transcript.
-          ...(watchWindow ? { lazy: true } : {}),
+          ...(watchWindow ? { lazy: true } : { omit_messages: true }),
           ...(sessionProfile ? { profile: sessionProfile } : {})
         })
 

apps/desktop/src/types/hermes.ts

@@ -600,6 +600,7 @@ export interface SessionResumeResponse {
   info?: SessionRuntimeInfo
   message_count: number
   messages: SessionMessage[]
+  messages_omitted?: boolean
   resumed: string
   running?: boolean
   session_id: string

tests/test_tui_gateway_server.py

@@ -2415,8 +2415,10 @@ def test_history_to_messages_keeps_real_user_bracket_text():
     ]
 
 
-def test_session_resume_uses_parent_lineage_for_display(monkeypatch):
+@pytest.mark.parametrize("omit_messages", [False, True])
+def test_session_resume_uses_parent_lineage_for_display(monkeypatch, omit_messages):
     captured = {}
+    target = "tip-omit" if omit_messages else "tip-full"
 
     class FakeDB:
         def get_session(self, target):
@@ -2466,15 +2468,25 @@ def get_messages_as_conversation(self, target, include_ancestors=False, repair_a
     # _neuter_agent_prewarm_timer fixture; this test only asserts the
     # returned display history.
 
+    params = {"session_id": target}
+    if omit_messages:
+        params["omit_messages"] = True
     resp = server.handle_request(
-        {"id": "1", "method": "session.resume", "params": {"session_id": "tip"}}
+        {"id": "1", "method": "session.resume", "params": params}
     )
 
-    assert resp["result"]["messages"] == [
+    expected = [] if omit_messages else [
         {"role": "user", "text": "root prompt"},
         {"role": "assistant", "text": "root answer"},
     ]
-    assert captured["history_calls"] == [("tip", False), ("tip", True)]
+    assert resp["result"]["messages"] == expected
+    assert resp["result"]["message_count"] == (1 if omit_messages else 2)
+    assert resp["result"]["messages_omitted"] is omit_messages
+    expected_calls = [(target, False)] if omit_messages else [
+        (target, False),
+        (target, True),
+    ]
+    assert captured["history_calls"] == expected_calls
 
 
 def test_live_visible_history_prefers_db_display_with_candidate():
@@ -12281,6 +12293,33 @@ def test_session_activate_switches_live_session_without_closing_siblings(monkeyp
         server._sessions.pop("sid-b", None)
 
 
+def test_session_activate_can_omit_duplicate_desktop_transcript(monkeypatch):
+    monkeypatch.setattr(server, "_session_info", lambda agent: {"model": agent.model})
+    server._sessions["sid-large"] = _session(
+        agent=types.SimpleNamespace(model="model-large"),
+        history=[
+            {"role": "user", "content": "large prompt"},
+            {"role": "assistant", "content": "large answer"},
+        ],
+        session_key="key-large",
+    )
+    try:
+        resp = server.handle_request(
+            {
+                "id": "1",
+                "method": "session.activate",
+                "params": {"session_id": "sid-large", "omit_messages": True},
+            }
+        )
+
+        assert resp["result"]["messages"] == []
+        assert resp["result"]["message_count"] == 2
+        assert resp["result"]["messages_omitted"] is True
+        assert resp["result"]["session_key"] == "key-large"
+    finally:
+        server._sessions.pop("sid-large", None)
+
+
 # ── session.most_recent ──────────────────────────────────────────────