diff --git a/apps/desktop/src/app/session/hooks/use-session-actions/resolve-stored-session.test.ts b/apps/desktop/src/app/session/hooks/use-session-actions/resolve-stored-session.test.ts
new file mode 100644
index 00000000000..41b6117d544
--- /dev/null
+++ b/apps/desktop/src/app/session/hooks/use-session-actions/resolve-stored-session.test.ts
@@ -0,0 +1,109 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+import type * as HermesModule from '@/hermes'
+import { getSession } from '@/hermes'
+import { $activeGatewayProfile, $profiles } from '@/store/profile'
+import { $sessions } from '@/store/session'
+import type { SessionInfo } from '@/types/hermes'
+
+import { resolveSessionProfile, resolveStoredSession } from './utils'
+
+vi.mock('@/hermes', async importActual => ({
+  ...(await importActual<typeof HermesModule>()),
+  getSession: vi.fn()
+}))
+
+const mockGetSession = vi.mocked(getSession)
+
+const session = (over: Partial<SessionInfo>): SessionInfo => over as SessionInfo
+
+const profiles = (...names: string[]) => names.map(name => ({ name }) as never)
+
+describe('resolveStoredSession profile ownership', () => {
+  beforeEach(() => {
+    $sessions.set([])
+    $profiles.set(profiles('default', 'meta'))
+    $activeGatewayProfile.set('meta')
+    mockGetSession.mockReset()
+  })
+
+  afterEach(() => {
+    $sessions.set([])
+    $profiles.set([])
+    $activeGatewayProfile.set('default')
+  })
+
+  it('returns a cached row that carries an owning profile', async () => {
+    $sessions.set([session({ id: 's1', profile: 'default' })])
+
+    const resolved = await resolveStoredSession('s1')
+
+    expect(resolved?.profile).toBe('default')
+    expect(mockGetSession).not.toHaveBeenCalled()
+  })
+
+  it('treats a profile-less cache hit as unresolved when multiple profiles exist', async () => {
+    $sessions.set([session({ id: 's1' })])
+    mockGetSession.mockRejectedValueOnce(new Error('404: Session not found'))
+    mockGetSession.mockResolvedValueOnce(session({ id: 's1', profile: 'default' }))
+
+    const resolved = await resolveStoredSession('s1')
+
+    expect(resolved?.profile).toBe('default')
+    // rung 2 (bare) then rung 3 (stamped cross-profile probe)
+    expect(mockGetSession).toHaveBeenNthCalledWith(1, 's1')
+    expect(mockGetSession).toHaveBeenNthCalledWith(2, 's1', 'default')
+  })
+
+  it('accepts a profile-less cache hit for single-profile users', async () => {
+    $profiles.set(profiles('default'))
+    $sessions.set([session({ id: 's1' })])
+
+    const resolved = await resolveStoredSession('s1')
+
+    expect(resolved?.id).toBe('s1')
+    expect(mockGetSession).not.toHaveBeenCalled()
+  })
+
+  it('stamps the active profile on a bare by-id hit from an older backend', async () => {
+    mockGetSession.mockResolvedValueOnce(session({ id: 's1' }))
+
+    const resolved = await resolveStoredSession('s1')
+
+    expect(resolved?.profile).toBe('meta')
+    // the upserted cache row is owned too, so the next hit short-circuits
+    expect($sessions.get().find(s => s.id === 's1')?.profile).toBe('meta')
+  })
+
+  it('probed desktop profile overrides a remote backend answering as its own "default"', async () => {
+    // Per-profile remote override: Electron strips the desktop alias before
+    // forwarding, so the standalone backend stamps its backend-local root.
+    mockGetSession.mockRejectedValueOnce(new Error('404: Session not found'))
+    mockGetSession.mockResolvedValueOnce(session({ id: 's1', profile: 'default' }))
+    $activeGatewayProfile.set('default')
+    $profiles.set(profiles('default', 'meta'))
+
+    const resolved = await resolveStoredSession('s1')
+
+    expect(resolved?.profile).toBe('meta')
+    expect($sessions.get().find(s => s.id === 's1')?.profile).toBe('meta')
+  })
+
+  it('stamps the probed profile on a scoped hit from an older backend that omits it', async () => {
+    mockGetSession.mockRejectedValueOnce(new Error('404: Session not found'))
+    mockGetSession.mockResolvedValueOnce(session({ id: 's1' }))
+
+    const resolved = await resolveStoredSession('s1')
+
+    expect(resolved?.profile).toBe('default')
+    // the cached row is owned too — no unowned row is ever re-cached
+    expect($sessions.get().find(s => s.id === 's1')?.profile).toBe('default')
+  })
+
+  it('resolveSessionProfile routes a default-profile session from a non-default gateway', async () => {
+    mockGetSession.mockRejectedValueOnce(new Error('404: Session not found'))
+    mockGetSession.mockResolvedValueOnce(session({ id: 's1', profile: 'default' }))
+
+    await expect(resolveSessionProfile('s1')).resolves.toBe('default')
+  })
+})
diff --git a/apps/desktop/src/app/session/hooks/use-session-actions/utils.ts b/apps/desktop/src/app/session/hooks/use-session-actions/utils.ts
index f6e19919f06..ffc799c432f 100644
--- a/apps/desktop/src/app/session/hooks/use-session-actions/utils.ts
+++ b/apps/desktop/src/app/session/hooks/use-session-actions/utils.ts
@@ -587,7 +587,13 @@ function upsertResolvedSession(session: SessionInfo, storedSessionId: string) {
 export async function resolveStoredSession(storedSessionId: string): Promise<SessionInfo | undefined> {
   const cached = $sessions.get().find(session => sessionMatchesStoredId(session, storedSessionId))
 
-  if (cached) {
+  // A row with no owning profile can't route a resume when more than one
+  // profile exists — a resume without a profile lands on whichever gateway is
+  // active (#67603 family, cross-profile open asymmetry). Treat such a hit as
+  // unresolved and fall through to the by-id lookups, which stamp ownership.
+  const multiProfile = $profiles.get().length > 1
+
+  if (cached && (cached.profile?.trim() || !multiProfile)) {
     return cached
   }
 
@@ -597,6 +603,12 @@ export async function resolveStoredSession(storedSessionId: string): Promise<Ses
   try {
     const session = await getSession(storedSessionId)
 
+    // Older backends omit `profile` on unscoped GETs; the serving backend is
+    // the active gateway's, so back-fill that rather than caching an unowned
+    // row. A present stamp is preserved: in app-global remote mode a bare hit
+    // can legitimately carry another profile's row (see the branch tests).
+    session.profile ||= normalizeProfileKey($activeGatewayProfile.get())
+
     upsertResolvedSession(session, storedSessionId)
 
     return session
@@ -618,6 +630,12 @@ export async function resolveStoredSession(storedSessionId: string): Promise<Ses
     try {
       const session = await getSession(storedSessionId, profile)
 
+      // Same ownership contract: the DESKTOP profile we explicitly probed is
+      // authoritative, whatever the scoped backend stamped (older backends
+      // omit the field; a per-profile remote override strips the alias before
+      // forwarding, so that backend answers as its own "default").
+      session.profile = profile
+
       upsertResolvedSession(session, storedSessionId)
 
       return session
diff --git a/hermes_cli/web_server.py b/hermes_cli/web_server.py
index f2d4ea11930..aa17beb9381 100644
--- a/hermes_cli/web_server.py
+++ b/hermes_cli/web_server.py
@@ -4986,14 +4986,17 @@ def get_sessions(
                 exclude_children=True,
             )
             now = time.time()
+            # Same ownership contract as get_session_detail: rows are stamped
+            # with the serving profile even when the request wasn't explicitly
+            # scoped, so default-profile rows never circulate unowned.
+            row_profile = profile_name or _cron_default_profile()
             for s in sessions:
                 s["is_active"] = (
                     s.get("ended_at") is None
                     and (now - s.get("last_active", s.get("started_at", 0))) < 300
                 )
-                if profile_name:
-                    s["profile"] = profile_name
-                    s["is_default_profile"] = profile_name == "default"
+                s["profile"] = row_profile
+                s["is_default_profile"] = row_profile == "default"
                 # SQLite stores the flag as 0/1; expose a real JSON boolean.
                 s["archived"] = bool(s.get("archived"))
             if not full:
@@ -11986,8 +11989,16 @@ async def get_session_detail(session_id: str, profile: Optional[str] = None):
         session = db.get_session(sid) if sid else None
         if not session:
             raise HTTPException(status_code=404, detail="Session not found")
-        if profile:
-            session["profile"] = _cron_profile_home(profile)[0]
+        # Always stamp the owning profile — the serving profile is known even
+        # when the request carries no ``?profile=`` (it's this process's own
+        # profile). Stamping only on explicit ``?profile=`` left rows for the
+        # default/primary profile systematically unowned, so multi-profile
+        # clients resolved them to whichever gateway happened to be active
+        # (cross-profile open asymmetry, #67603 family).
+        session["profile"] = (
+            _cron_profile_home(profile)[0] if profile else _cron_default_profile()
+        )
+        session["is_default_profile"] = session["profile"] == "default"
         return session
     finally:
         db.close()
diff --git a/tests/hermes_cli/test_web_server.py b/tests/hermes_cli/test_web_server.py
index 0acb0cb6956..8742e4ef7cf 100644
--- a/tests/hermes_cli/test_web_server.py
+++ b/tests/hermes_cli/test_web_server.py
@@ -1858,6 +1858,50 @@ class TestWebServerEndpoints:
         row = next(s for s in rows if s["id"] == "session-no-cwd")
         assert row["cwd"] is None
 
+    def test_session_detail_stamps_profile_without_query_param(self, monkeypatch):
+        """GET /api/sessions/{id} must carry the owning profile even when the
+        request has no ?profile= (bug: default-profile rows circulated unowned,
+        so multi-profile desktop clients resumed them on the wrong gateway).
+        """
+        from hermes_state import SessionDB
+
+        import hermes_cli.web_server as web_server
+
+        monkeypatch.setattr(web_server, "_cron_default_profile", lambda: "default")
+
+        db = SessionDB()
+        try:
+            db.create_session(session_id="detail-stamp", source="cli")
+        finally:
+            db.close()
+
+        resp = self.client.get("/api/sessions/detail-stamp")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["profile"] == "default"
+        assert data["is_default_profile"] is True
+
+    def test_session_list_stamps_profile_without_query_param(self, monkeypatch):
+        """GET /api/sessions rows must carry the serving profile even when the
+        request is unscoped (sibling of the detail-endpoint stamp gap)."""
+        from hermes_state import SessionDB
+
+        import hermes_cli.web_server as web_server
+
+        monkeypatch.setattr(web_server, "_cron_default_profile", lambda: "default")
+
+        db = SessionDB()
+        try:
+            db.create_session(session_id="list-stamp", source="cli")
+        finally:
+            db.close()
+
+        resp = self.client.get("/api/sessions?limit=20&offset=0")
+        assert resp.status_code == 200
+        row = next(s for s in resp.json()["sessions"] if s["id"] == "list-stamp")
+        assert row["profile"] == "default"
+        assert row["is_default_profile"] is True
+
     def test_get_sessions_forwards_min_messages(self, monkeypatch):
         """The ?min_messages= filter must reach SessionDB.