Follow latest child session on dashboard resume

hermes_cli/web_server.py

@@ -2173,6 +2173,83 @@ async def cancel_oauth_session(session_id: str, request: Request):
 # ---------------------------------------------------------------------------
 
 
+
+def _session_latest_descendant(session_id: str):
+    """Resolve a session id to the newest child leaf session.
+
+    /model may create child sessions. Dashboard refresh should continue the
+    newest child instead of reopening the old parent.
+    """
+    from hermes_state import SessionDB
+
+    def row_get(row, key, index):
+        if isinstance(row, dict):
+            return row.get(key)
+        try:
+            return row[key]
+        except Exception:
+            try:
+                return row[index]
+            except Exception:
+                return None
+
+    db = SessionDB()
+    try:
+        sid = db.resolve_session_id(session_id)
+        if not sid or not db.get_session(sid):
+            return None, []
+
+        conn = (
+            getattr(db, "conn", None)
+            or getattr(db, "_conn", None)
+            or getattr(db, "connection", None)
+            or getattr(db, "_connection", None)
+        )
+
+        rows = []
+        if conn is not None:
+            raw_rows = conn.execute(
+                "SELECT id, parent_session_id, started_at FROM sessions"
+            ).fetchall()
+            for row in raw_rows:
+                rows.append({
+                    "id": row_get(row, "id", 0),
+                    "parent_session_id": row_get(row, "parent_session_id", 1),
+                    "started_at": row_get(row, "started_at", 2),
+                })
+        else:
+            rows = db.list_sessions_rich(limit=10000, offset=0)
+
+        children = {}
+        for row in rows:
+            rid = row.get("id")
+            parent = row.get("parent_session_id")
+            if rid and parent:
+                children.setdefault(parent, []).append(row)
+
+        def started(row):
+            try:
+                return float(row.get("started_at") or 0)
+            except Exception:
+                return 0.0
+
+        current = sid
+        path = [sid]
+        seen = {sid}
+
+        while children.get(current):
+            candidates = [r for r in children[current] if r.get("id") not in seen]
+            if not candidates:
+                break
+            candidates.sort(key=started, reverse=True)
+            current = candidates[0]["id"]
+            path.append(current)
+            seen.add(current)
+
+        return current, path
+    finally:
+        db.close()
+
 @app.get("/api/sessions/{session_id}")
 async def get_session_detail(session_id: str):
     from hermes_state import SessionDB
@@ -2187,6 +2264,19 @@ async def get_session_detail(session_id: str):
         db.close()
 
 
+
+@app.get("/api/sessions/{session_id}/latest-descendant")
+async def get_session_latest_descendant(session_id: str):
+    latest, path = _session_latest_descendant(session_id)
+    if not latest:
+        raise HTTPException(status_code=404, detail="Session not found")
+    return {
+        "requested_session_id": path[0] if path else session_id,
+        "session_id": latest,
+        "path": path,
+        "changed": bool(path and latest != path[0]),
+    }
+
 @app.get("/api/sessions/{session_id}/messages")
 async def get_session_messages(session_id: str):
     from hermes_state import SessionDB
@@ -2958,6 +3048,9 @@ def _resolve_chat_argv(
     env.setdefault("HERMES_TUI_DISABLE_MOUSE", "1")
 
     if resume:
+        latest_resume, _latest_path = _session_latest_descendant(resume)
+        if latest_resume:
+            resume = latest_resume
         env["HERMES_TUI_RESUME"] = resume
 
     if sidecar_url:

web/src/lib/api.ts

@@ -49,6 +49,10 @@ export const api = {
     fetchJSON<PaginatedSessions>(`/api/sessions?limit=${limit}&offset=${offset}`),
   getSessionMessages: (id: string) =>
     fetchJSON<SessionMessagesResponse>(`/api/sessions/${encodeURIComponent(id)}/messages`),
+  getSessionLatestDescendant: (id: string) =>
+    fetchJSON<SessionLatestDescendantResponse>(
+      `/api/sessions/${encodeURIComponent(id)}/latest-descendant`,
+    ),
   deleteSession: (id: string) =>
     fetchJSON<{ ok: boolean }>(`/api/sessions/${encodeURIComponent(id)}`, {
       method: "DELETE",
@@ -373,6 +377,14 @@ export interface SessionInfo {
   input_tokens: number;
   output_tokens: number;
   preview: string | null;
+  parent_session_id?: string | null;
+}
+
+export interface SessionLatestDescendantResponse {
+  requested_session_id: string;
+  session_id: string;
+  path: string[];
+  changed: boolean;
 }
 
 export interface PaginatedSessions {

web/src/pages/ChatPage.tsx

@@ -33,6 +33,7 @@ import { useSearchParams } from "react-router-dom";
 import { ChatSidebar } from "@/components/ChatSidebar";
 import { usePageHeader } from "@/contexts/usePageHeader";
 import { useI18n } from "@/i18n";
+import { api } from "@/lib/api";
 import { PluginSlot } from "@/plugins";
 
 function buildWsUrl(
@@ -111,7 +112,7 @@ export default function ChatPage({ isActive = true }: { isActive?: boolean }) {
   // the moment `isActive` flips back to true (display:none → display:flex
   // collapses the host's box, so ResizeObserver never fires on return).
   const syncMetricsRef = useRef<(() => void) | null>(null);
-  const [searchParams] = useSearchParams();
+  const [searchParams, setSearchParams] = useSearchParams();
   // Lazy-init: the missing-token check happens at construction so the effect
   // body doesn't have to setState (React 19's set-state-in-effect rule).
   const [banner, setBanner] = useState<string | null>(() =>
@@ -153,8 +154,33 @@ export default function ChatPage({ isActive = true }: { isActive?: boolean }) {
   // Sessions page relies on `/chat?resume=<id>` changing at runtime, so we must
   // treat the current resume target as part of the PTY identity and rebuild the
   // terminal session when it changes.
-  const resumeId = searchParams.get("resume");
+  const resumeParam = searchParams.get("resume");
-  const channel = useMemo(() => generateChannelId(), [resumeId]);
+  const channel = useMemo(() => generateChannelId(), [resumeParam]);
+
+  useEffect(() => {
+    if (!resumeParam) return;
+
+    let cancelled = false;
+
+    api
+      .getSessionLatestDescendant(resumeParam)
+      .then((res) => {
+        if (cancelled || !res.session_id || res.session_id === resumeParam) {
+          return;
+        }
+
+        const next = new URLSearchParams(searchParams);
+        next.set("resume", res.session_id);
+        setSearchParams(next, { replace: true });
+      })
+      .catch(() => {
+        // Best-effort: old servers or missing sessions should not block chat.
+      });
+
+    return () => {
+      cancelled = true;
+    };
+  }, [resumeParam, searchParams, setSearchParams]);
 
   useEffect(() => {
     const mql = window.matchMedia("(max-width: 1023px)");