diff --git a/packages/core/agents/stores/view-store.test.ts b/packages/core/agents/stores/view-store.test.ts
index 3f9ce176b..7cb5397da 100644
--- a/packages/core/agents/stores/view-store.test.ts
+++ b/packages/core/agents/stores/view-store.test.ts
@@ -100,4 +100,25 @@ describe("useAgentsViewStore", () => {
     expect(useAgentsViewStore.getState().scope).toBe("mine");
     expect(localStorage.getItem("multica_agents_view:acme")).not.toBeNull();
   });
+
+  it("backfills new filter dimensions when rehydrating a pre-owners payload", async () => {
+    // A payload persisted before the `owners` filter existed must not drop
+    // the key to undefined (the agents list filter predicate reads
+    // `filters.owners.length` and would crash).
+    localStorage.setItem(
+      "multica_agents_view:acme",
+      JSON.stringify({
+        state: { filters: { availability: ["online"], runtimes: [] } },
+        version: 0,
+      }),
+    );
+
+    setCurrentWorkspace("acme", "ws_a");
+    await flush();
+    await flush();
+
+    const filters = useAgentsViewStore.getState().filters;
+    expect(filters.owners).toEqual([]);
+    expect(filters.availability).toEqual(["online"]);
+  });
 });
diff --git a/packages/core/agents/stores/view-store.ts b/packages/core/agents/stores/view-store.ts
index e61f8d02a..1cf0b0e5a 100644
--- a/packages/core/agents/stores/view-store.ts
+++ b/packages/core/agents/stores/view-store.ts
@@ -171,7 +171,15 @@ export const useAgentsViewStore = create<AgentsViewState>()(
       // persisted is undefined, which would leak state across workspaces.
       merge: (persisted, current) => {
         if (!persisted) return { ...current, ...DEFAULTS };
-        return { ...current, ...(persisted as Partial<AgentsViewState>) };
+        const p = persisted as Partial<AgentsViewState>;
+        // Deep-merge filters so a payload persisted before a new filter
+        // dimension existed (e.g. `owners`) still gets that key's default
+        // instead of dropping it to `undefined` and crashing `.length`.
+        return {
+          ...current,
+          ...p,
+          filters: { ...EMPTY_AGENT_FILTERS, ...(p.filters ?? {}) },
+        };
       },
     },
   ),