diff --git a/ui/src/ui/controllers/dreaming.test.ts b/ui/src/ui/controllers/dreaming.test.ts
index a2dea66e854..5ac5a901de3 100644
--- a/ui/src/ui/controllers/dreaming.test.ts
+++ b/ui/src/ui/controllers/dreaming.test.ts
@@ -193,6 +193,48 @@ describe("dreaming controller", () => {
     });
   });
 
+  it("blocks dreaming patch when selected plugin config rejects unknown keys", async () => {
+    const { state, request } = createState();
+    state.configSnapshot = {
+      hash: "hash-1",
+      config: {
+        plugins: {
+          slots: {
+            memory: "memory-lancedb",
+          },
+        },
+      },
+    };
+    request.mockImplementation(async (method: string) => {
+      if (method === "config.schema.lookup") {
+        return {
+          path: "plugins.entries.memory-lancedb.config",
+          schema: {
+            type: "object",
+            additionalProperties: false,
+          },
+          children: [
+            { key: "retentionDays", path: "plugins.entries.memory-lancedb.config.retentionDays" },
+          ],
+        };
+      }
+      if (method === "config.patch") {
+        return { ok: true };
+      }
+      return {};
+    });
+
+    const ok = await updateDreamingEnabled(state, true);
+
+    expect(ok).toBe(false);
+    expect(request).toHaveBeenCalledWith("config.schema.lookup", {
+      path: "plugins.entries.memory-lancedb.config",
+    });
+    expect(request).not.toHaveBeenCalledWith("config.patch", expect.anything());
+    expect(state.dreamingStatusError).toContain("memory-lancedb");
+    expect(state.dreamingStatusError).toContain("does not support dreaming settings");
+  });
+
   it("reads dreaming enabled state from the selected memory slot plugin", () => {
     expect(
       resolveConfiguredDreaming({
diff --git a/ui/src/ui/controllers/dreaming.ts b/ui/src/ui/controllers/dreaming.ts
index 6060555fe19..5f05cc4cb7d 100644
--- a/ui/src/ui/controllers/dreaming.ts
+++ b/ui/src/ui/controllers/dreaming.ts
@@ -309,11 +309,65 @@ async function writeDreamingPatch(
   }
 }
 
+function lookupIncludesDreamingProperty(value: unknown): boolean {
+  const lookup = asRecord(value);
+  const children = Array.isArray(lookup?.children) ? lookup.children : [];
+  for (const child of children) {
+    const childRecord = asRecord(child);
+    if (normalizeTrimmedString(childRecord?.key) === "dreaming") {
+      return true;
+    }
+  }
+  return false;
+}
+
+function lookupDisallowsUnknownProperties(value: unknown): boolean {
+  const lookup = asRecord(value);
+  const schema = asRecord(lookup?.schema);
+  return schema?.additionalProperties === false;
+}
+
+async function ensureDreamingPathSupported(
+  state: DreamingState,
+  pluginId: string,
+): Promise<boolean> {
+  if (!state.client || !state.connected) {
+    return true;
+  }
+  try {
+    const lookup = await state.client.request("config.schema.lookup", {
+      path: `plugins.entries.${pluginId}.config`,
+    });
+    if (lookupIncludesDreamingProperty(lookup)) {
+      return true;
+    }
+    if (lookupDisallowsUnknownProperties(lookup)) {
+      const message = `Selected memory plugin "${pluginId}" does not support dreaming settings.`;
+      state.dreamingStatusError = message;
+      state.lastError = message;
+      return false;
+    }
+  } catch {
+    return true;
+  }
+  return true;
+}
+
 export async function updateDreamingEnabled(
   state: DreamingState,
   enabled: boolean,
 ): Promise<boolean> {
+  if (state.dreamingModeSaving) {
+    return false;
+  }
+  if (!state.configSnapshot?.hash) {
+    state.dreamingStatusError = "Config hash missing; refresh and retry.";
+    return false;
+  }
   const { pluginId } = resolveConfiguredDreaming(asRecord(state.configSnapshot?.config) ?? null);
+  if (!(await ensureDreamingPathSupported(state, pluginId))) {
+    return false;
+  }
   const ok = await writeDreamingPatch(state, {
     plugins: {
       entries: {