fix(session): follow compression continuations for transcript reads (#34089)

gateway/platforms/api_server.py

@@ -1480,10 +1480,11 @@ async def _handle_session_messages(self, request: "web.Request") -> "web.Respons
         if err:
             return err
         db = self._ensure_session_db()
-        messages = db.get_messages(session_id)
+        resolved_id = db.resolve_resume_session_id(session_id)
+        messages = db.get_messages(resolved_id)
         return web.json_response({
             "object": "list",
-            "session_id": session_id,
+            "session_id": resolved_id,
             "data": [self._message_response(m) for m in messages],
         })
 

hermes_cli/web_server.py

@@ -5470,6 +5470,7 @@ async def get_session_messages(session_id: str, profile: Optional[str] = None):
         sid = db.resolve_session_id(session_id)
         if not sid:
             raise HTTPException(status_code=404, detail="Session not found")
+        sid = db.resolve_resume_session_id(sid)
         messages = db.get_messages(sid)
         return {"session_id": sid, "messages": messages}
     finally:

tests/gateway/test_session_api.py

@@ -121,6 +121,26 @@ async def test_session_crud_and_message_history(adapter, session_db):
         assert session_db.get_session(session_id) is None
 
 
+@pytest.mark.asyncio
+async def test_session_messages_follow_compression_tip(adapter, session_db):
+    source_id = session_db.create_session("source-session", "api_server")
+    session_db.append_message(source_id, "user", "before compression")
+    session_db.end_session(source_id, "compression")
+    session_db.create_session("tip-session", "api_server", parent_session_id=source_id)
+    session_db.replace_messages(source_id, [])
+    session_db.append_message("tip-session", "user", "after compression")
+
+    app = _create_session_app(adapter)
+    async with TestClient(TestServer(app)) as cli:
+        messages_resp = await cli.get(f"/api/sessions/{source_id}/messages")
+        assert messages_resp.status == 200
+        messages = await messages_resp.json()
+
+    assert messages["object"] == "list"
+    assert messages["session_id"] == "tip-session"
+    assert [m["content"] for m in messages["data"]] == ["after compression"]
+
+
 @pytest.mark.asyncio
 async def test_session_fork_uses_current_sessiondb_branch_primitives(adapter, session_db):
     source_id = session_db.create_session("source-session", "api_server", model="test-model")

tests/hermes_cli/test_web_server.py

@@ -638,6 +638,37 @@ def test_search_keeps_branch_specific_hits_on_branch(self):
             for r in results
         )
 
+    def test_get_session_messages_follows_compression_tip(self):
+        """Reading a compressed session by its old id should hydrate from the
+        live continuation, matching /resume behavior."""
+        import time as _time
+
+        from hermes_state import SessionDB
+
+        db = SessionDB()
+        try:
+            db.create_session(session_id="desktop-root", source="cli")
+            db.append_message(session_id="desktop-root", role="user", content="before compression")
+            db.end_session("desktop-root", "compression")
+            now = _time.time()
+            db._conn.execute(
+                "UPDATE sessions SET started_at = ?, ended_at = ? WHERE id = ?",
+                (now - 10, now - 5, "desktop-root"),
+            )
+            db.create_session(session_id="desktop-tip", source="cli", parent_session_id="desktop-root")
+            db._conn.execute("UPDATE sessions SET started_at = ? WHERE id = ?", (now - 4, "desktop-tip"))
+            db.replace_messages("desktop-root", [])
+            db.append_message(session_id="desktop-tip", role="user", content="after compression")
+            db._conn.commit()
+        finally:
+            db.close()
+
+        resp = self.client.get("/api/sessions/desktop-root/messages")
+        assert resp.status_code == 200
+        payload = resp.json()
+        assert payload["session_id"] == "desktop-tip"
+        assert [m["content"] for m in payload["messages"]] == ["after compression"]
+
     def test_get_sessions_archived_is_boolean(self):
         from hermes_state import SessionDB