diff --git a/js/app.js b/js/app.js
index 922563f6..24317161 100644
--- a/js/app.js
+++ b/js/app.js
@@ -482,19 +482,38 @@ class Application {
 
       await Promise.all([accessControlPromise, adminPanePromise]);
 
-      if (!this.pubkey && nostrClient.sessionActor?.pubkey) {
+      const syncSessionActorBlacklist = async (trigger) => {
+        if (this.pubkey) {
+          return;
+        }
+
+        const sessionActorPubkey = nostrClient.sessionActor?.pubkey;
+        if (!sessionActorPubkey) {
+          return;
+        }
+
         const blacklist = accessControl.getBlacklist();
         try {
-          await userBlocks.seedLocalBaseline(
-            nostrClient.sessionActor.pubkey,
+          await userBlocks.seedBaselineDelta(
+            sessionActorPubkey,
             Array.from(blacklist || []),
           );
         } catch (error) {
           devLogger.warn(
-            "[app.init()] Failed to seed local baseline for session actor:",
+            `[app.init()] Failed to sync session actor blacklist${
+              trigger ? ` (${trigger})` : ""
+            }:`,
             error,
           );
         }
+      };
+
+      await syncSessionActorBlacklist("post-refresh");
+
+      if (typeof accessControl.onBlacklistChange === "function") {
+        accessControl.onBlacklistChange(() => {
+          syncSessionActorBlacklist("blacklist-change");
+        });
       }
 
       // Grab the "Subscriptions" link by its id in the sidebar
diff --git a/js/userBlocks.js b/js/userBlocks.js
index 57669725..3b4efc80 100644
--- a/js/userBlocks.js
+++ b/js/userBlocks.js
@@ -1443,6 +1443,63 @@ class UserBlockListManager {
     return { ok: true, seeded: true, addedPubkeys: Array.from(additions) };
   }
 
+  async seedBaselineDelta(userPubkey, candidateNpubs = []) {
+    const actorHex = normalizeHex(userPubkey);
+    if (!actorHex) {
+      return { ok: false, seeded: false, reason: "invalid-user" };
+    }
+
+    await this.ensureLoaded(actorHex);
+
+    const state = this._getSeedState(actorHex);
+    const removals = state.removals;
+    const additions = new Set();
+
+    const candidates = Array.isArray(candidateNpubs) ? candidateNpubs : [];
+    for (const candidate of candidates) {
+      const candidateHex = normalizeHex(candidate);
+      if (!candidateHex) {
+        continue;
+      }
+      if (candidateHex === actorHex) {
+        continue;
+      }
+      if (this.blockedPubkeys.has(candidateHex)) {
+        continue;
+      }
+      if (removals.has(candidateHex)) {
+        continue;
+      }
+      additions.add(candidateHex);
+    }
+
+    if (!additions.size) {
+      if (!state.seeded) {
+        this._setSeeded(actorHex, true);
+      }
+      return { ok: true, seeded: state.seeded, reason: "no-candidates" };
+    }
+
+    additions.forEach((hex) => this.blockedPubkeys.add(hex));
+
+    this._setSeeded(actorHex, true);
+    this._saveLocal(actorHex);
+
+    try {
+      this.emitter.emit(USER_BLOCK_EVENTS.CHANGE, {
+        action: "seed-delta",
+        actorPubkey: actorHex,
+        blockedPubkeys: Array.from(this.blockedPubkeys),
+        addedPubkeys: Array.from(additions),
+        localOnly: true,
+      });
+    } catch (error) {
+      userLogger.warn("[UserBlockList] Failed to emit delta seed change event:", error);
+    }
+
+    return { ok: true, seeded: true, addedPubkeys: Array.from(additions) };
+  }
+
   async addBlock(targetPubkey, userPubkey) {
     const actorHex = normalizeHex(userPubkey);
     if (!actorHex) {