diff --git a/scripts/check-architecture-guardrails.mjs b/scripts/check-architecture-guardrails.mjs
index 1c3008b..c0512f6 100644
--- a/scripts/check-architecture-guardrails.mjs
+++ b/scripts/check-architecture-guardrails.mjs
@@ -100,6 +100,40 @@ export const rules = [
     ],
     forbidden: [],
   },
+  {
+    file: "apps/web/src/hooks/timelineLivePreview.ts",
+    maxLines: 140,
+    required: [
+      {
+        pattern: /\bexport function scheduleLivePreview\b/,
+        message: "timeline live preview helpers must keep frame scheduling centralized",
+      },
+      {
+        pattern: /\bexport function clearLivePreview\b/,
+        message: "timeline live preview helpers must keep preview reset logic centralized",
+      },
+      {
+        pattern: /\bexport function preserveLivePreview\b/,
+        message: "timeline live preview helpers must keep snapshot preservation centralized",
+      },
+    ],
+    forbidden: [],
+  },
+  {
+    file: "apps/web/src/hooks/useTimelineDrag.ts",
+    required: [
+      {
+        pattern: /from "\.\/timelineLivePreview\.js"/,
+        message: "timeline drag must keep live preview behavior delegated to the extracted helper module",
+      },
+    ],
+    forbidden: [
+      {
+        pattern: /\bfunction (?:toPxValue|joinTransforms|captureLivePreviewTargets|renderLivePreview|scheduleLivePreview|clearLivePreview|datesMatch|preserveLivePreview)\b/,
+        message: "timeline drag must not re-inline live preview helper implementations",
+      },
+    ],
+  },
   {
     file: "docker-compose.prod.yml",
     required: [
diff --git a/scripts/check-architecture-guardrails.test.mjs b/scripts/check-architecture-guardrails.test.mjs
index 235de3f..cd13cd1 100644
--- a/scripts/check-architecture-guardrails.test.mjs
+++ b/scripts/check-architecture-guardrails.test.mjs
@@ -4,6 +4,7 @@ import {
   collectArchitectureGuardrailViolations,
   countLines,
   evaluateRule,
+  rules,
 } from "./check-architecture-guardrails.mjs";
 
 describe("architecture guardrails", () => {
@@ -66,4 +67,22 @@ describe("architecture guardrails", () => {
       "apps/web/src/example.ts: file grew to 4 lines and exceeds maxLines=2; split the ownership surface before expanding it further",
     ]);
   });
+
+  it("guards the extracted timeline live preview ownership boundary", () => {
+    const dragRule = rules.find((rule) => rule.file === "apps/web/src/hooks/useTimelineDrag.ts");
+    const livePreviewRule = rules.find((rule) => rule.file === "apps/web/src/hooks/timelineLivePreview.ts");
+
+    assert.ok(dragRule);
+    assert.ok(livePreviewRule);
+
+    assert.deepEqual(evaluateRule(dragRule, "function clearLivePreview() {}\n"), [
+      "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep live preview behavior delegated to the extracted helper module",
+      "apps/web/src/hooks/useTimelineDrag.ts: forbidden pattern matched: timeline drag must not re-inline live preview helper implementations",
+    ]);
+
+    assert.deepEqual(evaluateRule(livePreviewRule, "export function scheduleLivePreview() {}\n"), [
+      "apps/web/src/hooks/timelineLivePreview.ts: missing guardrail anchor: timeline live preview helpers must keep preview reset logic centralized",
+      "apps/web/src/hooks/timelineLivePreview.ts: missing guardrail anchor: timeline live preview helpers must keep snapshot preservation centralized",
+    ]);
+  });
 });