enhance: sync startup latency

1. Removes startup dependency on remote-graphs fetch for initial sync start.
2. Removes unnecessary restart churn.
3. Shaves trigger scheduling delay.

src/main/frontend/handler/db_based/rtc_flows.cljs

@@ -153,4 +153,4 @@ conditions:
    (apply c.m/mix)
    (m/latest vector flows/current-login-user-flow)
    (m/eduction (keep (fn [[current-user trigger-event]] (when current-user trigger-event))))
-   (c.m/debounce 200)))
+   (c.m/debounce 50)))

src/main/frontend/handler/db_based/sync.cljs

@@ -185,6 +185,23 @@
   [repo]
   (some #(= repo (:url %)) (state/get-rtc-graphs)))
 
+(defn- graph-has-local-rtc-id?
+  [repo]
+  (boolean (some-> (db/get-db repo)
+                   ldb/get-graph-rtc-uuid)))
+
+(defn- remote-graphs-unknown?
+  []
+  (not= false (:rtc/loading-graphs? @state/state)))
+
+(defn- should-start-rtc?
+  [repo]
+  (or (graph-in-remote-list? repo)
+      ;; During startup, remote graph list might not be fetched yet.
+      ;; If local DB already has graph UUID, start optimistically to reduce cold-start latency.
+      (and (remote-graphs-unknown?)
+           (graph-has-local-rtc-id? repo))))
+
 (defn- normalize-graph-e2ee?
   [graph-e2ee?]
   (if (nil? graph-e2ee?)
@@ -193,12 +210,14 @@
 
 (defn <rtc-start!
   [repo & {:keys [_stop-before-start?] :as _opts}]
-  (if (graph-in-remote-list? repo)
+  (if (should-start-rtc? repo)
     (do
       (log/info :db-sync/start {:repo repo})
       (state/<invoke-db-worker :thread-api/db-sync-start repo))
     (do
-      (log/info :db-sync/skip-start {:repo repo :reason :graph-not-in-remote-list})
+      (log/info :db-sync/skip-start {:repo repo :reason :graph-not-in-remote-list
+                                     :remote-graphs-loading? (:rtc/loading-graphs? @state/state)
+                                     :has-local-rtc-id? (graph-has-local-rtc-id? repo)})
       (p/resolved nil))))
 
 (defn <rtc-stop!

src/main/frontend/handler/user.cljs

@@ -37,6 +37,13 @@
           (js->clj :keywordize-keys true)
           (update :cognito:username decode-username)))
 
+(defn- parse-jwt-safe
+  [jwt]
+  (try
+    (parse-jwt jwt)
+    (catch :default _
+      nil)))
+
 (defn- expired? [parsed-jwt]
   (some->
    (* 1000 (:exp parsed-jwt))
@@ -191,12 +198,34 @@
   "Refresh id-token&access-token, pull latest repos, returns nil when tokens are not available."
   []
   (println "restore-tokens-from-localstorage")
-  (let [refresh-token (js/localStorage.getItem "refresh-token")]
-    (when refresh-token
+  (let [refresh-token (js/localStorage.getItem "refresh-token")
+        id-token (js/localStorage.getItem "id-token")
+        access-token (js/localStorage.getItem "access-token")
+        restored-from-cache?
+        (boolean
+         (when (and (string? refresh-token) (not (string/blank? refresh-token))
+                    (string? id-token) (not (string/blank? id-token))
+                    (string? access-token) (not (string/blank? access-token)))
+           (when-let [parsed (parse-jwt-safe id-token)]
+             (when-not (expired? parsed)
+               (set-tokens! id-token access-token refresh-token)
+               true))))
+        should-refresh?
+        (and (string? refresh-token)
+             (not (string/blank? refresh-token))
+             (or (not restored-from-cache?)
+                 (some-> (state/get-auth-id-token)
+                         parse-jwt-safe
+                         almost-expired?)))]
+    (when restored-from-cache?
+      ;; Publish login event immediately so sync can start without waiting token refresh request.
+      (state/pub-event! [:user/fetch-info-and-graphs]))
+    (when should-refresh?
       (go
         (<! (<refresh-id-token&access-token))
-        ;; refresh remote graph list by pub login event
-        (when (user-uuid) (state/pub-event! [:user/fetch-info-and-graphs]))))))
+        ;; If tokens were not restored from cache, this is the first chance to continue login flow.
+        (when (and (not restored-from-cache?) (user-uuid))
+          (state/pub-event! [:user/fetch-info-and-graphs]))))))
 
 (defn login-callback
   [session]

src/main/frontend/worker/sync.cljs

@@ -1311,22 +1311,40 @@
     (reset! worker-state/*db-sync-client nil))
   (p/resolved nil))
 
+(defn- active-client-for?
+  [client repo graph-id]
+  (when (and client (= repo (:repo client)) (= graph-id (:graph-id client)))
+    (let [ws (:ws client)
+          ws-state (some-> (:ws-state client) deref)
+          ws-ready-state (when ws (ready-state ws))]
+      (or (= :open ws-state)
+          (contains? #{0 1} ws-ready-state)))))
+
 (defn start!
   [repo]
-  (p/do!
-   (stop!)
-   (let [base (ws-base-url)
-         graph-id (get-graph-id repo)]
-     (if (and (string? base) (seq base) (seq graph-id))
+  (let [base (ws-base-url)
+        graph-id (get-graph-id repo)
+        current @worker-state/*db-sync-client]
+    (cond
+      (not (and (string? base) (seq base) (seq graph-id)))
+      (do
+        (log/info :db-sync/start-skipped {:repo repo :graph-id graph-id :base base})
+        (p/resolved nil))
+
+      (active-client-for? current repo graph-id)
+      (do
+        (broadcast-rtc-state! current)
+        (p/resolved nil))
+
+      :else
+      (p/do!
+       (stop!)
        (let [client (ensure-client-state! repo)
              url (format-ws-url base graph-id)
              _ (ensure-client-graph-uuid! repo graph-id)
              connected (assoc client :graph-id graph-id)
              connected (connect! repo connected url)]
          (reset! worker-state/*db-sync-client connected)
-         (p/resolved nil))
-       (do
-         (log/info :db-sync/start-skipped {:repo repo :graph-id graph-id :base base})
          (p/resolved nil))))))
 
 (defn enqueue-local-tx!

src/main/mobile/components/header.cljs

@@ -152,7 +152,7 @@
     (reset! native-top-bar-listener? true)))
 
 (defn- configure-native-top-bar!
-  [repo {:keys [tab title route-name route-view sync-color favorited? show-sync?]}]
+  [{:keys [tab title route-name route-view sync-color favorited? show-sync?]}]
   (when (and (mobile-util/native-platform?)
              mobile-util/native-top-bar)
     (let [hidden? (and (mobile-util/native-ios?) (= tab "search"))
@@ -247,7 +247,6 @@
                title (or (:block/title block) fallback-title)
                f (fn [favorited?]
                    (configure-native-top-bar!
-                    current-repo
                     {:tab tab
                      :title title
                      :route-name route-name
@@ -277,7 +276,6 @@
                           title (:block/title block)
                           f (fn [favorited?]
                               (configure-native-top-bar!
-                               current-repo
                                {:tab tab
                                 :title title
                                 :route-name route-name