diff --git a/design/10-review/process/16-mnote-web-runtime-module-maintainability-checklist-v1.md b/design/10-review/process/16-mnote-web-runtime-module-maintainability-checklist-v1.md
index fc210625..879c90d7 100644
--- a/design/10-review/process/16-mnote-web-runtime-module-maintainability-checklist-v1.md
+++ b/design/10-review/process/16-mnote-web-runtime-module-maintainability-checklist-v1.md
@@ -205,7 +205,7 @@ cargo test --manifest-path rust/Cargo.toml -p mnote-web --lib ssr::pages::layout
 拆分项：
 
 - [ ] D1. `tree-shell-state-runtime.js`：state hydration、serialization、patch dispatch。
-- [ ] D2. `tree-shell-page-runtime.js`：page tree keyboard、expand、focus、drag/drop intent。
+- [x] D2. `tree-shell-page-runtime.js`：page tree keyboard、expand、focus、drag/drop intent。
 - [ ] D3. `tree-shell-filetree-runtime.js`：filetree row normalization、resource meta、open target。
 - [ ] D4. `tree-shell-picker-runtime.js`：picker search/focus/pick root。
 - [ ] D5. `tree-shell-dom-runtime.js`：DOM patch/render helpers。
diff --git a/rust/crates/mnote-web/browser/tree-shell-page-runtime.js b/rust/crates/mnote-web/browser/tree-shell-page-runtime.js
new file mode 100644
index 00000000..fb037c15
--- /dev/null
+++ b/rust/crates/mnote-web/browser/tree-shell-page-runtime.js
@@ -0,0 +1,55 @@
+// MNote debug /tree shell page-mode runtime helpers.
+
+export async function reducePageActionWithRuntime(runtimeContext, action, item) {
+  if (runtimeContext.mode !== "page" || !runtimeContext.runtimeReduceEndpoint) {
+    return null;
+  }
+  const runtimeAction = runtimeContext.buildPageRuntimeAction(action, item);
+  if (!runtimeAction) return null;
+  const response = await fetch(runtimeContext.runtimeReduceEndpoint, {
+    method: "POST",
+    headers: { "content-type": "application/json" },
+    body: JSON.stringify({
+      mode: "page",
+      requestId: `page-runtime-${Date.now()}`,
+      environment: runtimeContext.buildPageRuntimeEnvironment(),
+      state: runtimeContext.readPageRuntimeState(action, item),
+      action: runtimeAction,
+    }),
+  });
+  if (!response.ok) {
+    throw new Error(await runtimeContext.readErrorMessage(response));
+  }
+  return response.json();
+}
+
+export function reconcilePageRuntimeResult(runtimeContext, runtimeResult, item) {
+  const result = runtimeContext.normalizePageRuntimeResult(runtimeResult);
+  if (!result) return false;
+  const previousExpanded = new Set(runtimeContext.expanded);
+  let shouldPatchTree = false;
+  if (Array.isArray(result.expandedIds)) {
+    shouldPatchTree =
+      runtimeContext.commitPageExpandedIds(result.expandedIds) || shouldPatchTree;
+  }
+  const currentFocusedNodeId = runtimeContext.getFocusedNodeId();
+  if (result.focusedId && result.focusedId !== currentFocusedNodeId) {
+    runtimeContext.setFocusedNodeId(result.focusedId);
+    runtimeContext.postPageFocusChange(result.focusedId);
+    shouldPatchTree = true;
+  }
+  const itemNodeId = runtimeContext.normalizeText(item?.nodeId);
+  if (
+    itemNodeId &&
+    previousExpanded.has(itemNodeId) !== runtimeContext.expanded.has(itemNodeId)
+  ) {
+    runtimeContext.postPageExpandChange(itemNodeId, runtimeContext.expanded.has(itemNodeId));
+  }
+  if (shouldPatchTree) {
+    runtimeContext.patchPageTreeAfterRuntimeState(
+      Array.isArray(result.expandedIds) ? [itemNodeId, ...result.expandedIds] : [itemNodeId],
+      result.focusedId || runtimeContext.getFocusedNodeId(),
+    );
+  }
+  return shouldPatchTree;
+}
diff --git a/rust/crates/mnote-web/browser/tree-shell-runtime.js b/rust/crates/mnote-web/browser/tree-shell-runtime.js
index d857c400..a753b27e 100644
--- a/rust/crates/mnote-web/browser/tree-shell-runtime.js
+++ b/rust/crates/mnote-web/browser/tree-shell-runtime.js
@@ -1,6 +1,11 @@
 // MNote debug /tree shell 浏览器运行时外置模块。
 // 该文件由 tree.rs 原 inline runtime 同构迁出，语义仍由 Rust tree_shell reducer 主导。
 
+import {
+  reconcilePageRuntimeResult,
+  reducePageActionWithRuntime,
+} from "./tree-shell-page-runtime.js";
+
 function buildFileTreeRuntimeEnvironment(runtimeContext) {
   const fileTreeRowById = runtimeContext.fileTreeRowById || new Map();
   return {
@@ -17,60 +22,6 @@ function buildFileTreeRuntimeEnvironment(runtimeContext) {
   };
 }
 
-async function reducePageActionWithRuntime(runtimeContext, action, item) {
-  if (runtimeContext.mode !== "page" || !runtimeContext.runtimeReduceEndpoint) {
-    return null;
-  }
-  const runtimeAction = runtimeContext.buildPageRuntimeAction(action, item);
-  if (!runtimeAction) return null;
-  const response = await fetch(runtimeContext.runtimeReduceEndpoint, {
-    method: "POST",
-    headers: { "content-type": "application/json" },
-    body: JSON.stringify({
-      mode: "page",
-      requestId: `page-runtime-${Date.now()}`,
-      environment: runtimeContext.buildPageRuntimeEnvironment(),
-      state: runtimeContext.readPageRuntimeState(action, item),
-      action: runtimeAction,
-    }),
-  });
-  if (!response.ok) {
-    throw new Error(await runtimeContext.readErrorMessage(response));
-  }
-  return response.json();
-}
-
-function reconcilePageRuntimeResult(runtimeContext, runtimeResult, item) {
-  const result = runtimeContext.normalizePageRuntimeResult(runtimeResult);
-  if (!result) return false;
-  const previousExpanded = new Set(runtimeContext.expanded);
-  let shouldPatchTree = false;
-  if (Array.isArray(result.expandedIds)) {
-    shouldPatchTree =
-      runtimeContext.commitPageExpandedIds(result.expandedIds) || shouldPatchTree;
-  }
-  const currentFocusedNodeId = runtimeContext.getFocusedNodeId();
-  if (result.focusedId && result.focusedId !== currentFocusedNodeId) {
-    runtimeContext.setFocusedNodeId(result.focusedId);
-    runtimeContext.postPageFocusChange(result.focusedId);
-    shouldPatchTree = true;
-  }
-  const itemNodeId = runtimeContext.normalizeText(item?.nodeId);
-  if (
-    itemNodeId &&
-    previousExpanded.has(itemNodeId) !== runtimeContext.expanded.has(itemNodeId)
-  ) {
-    runtimeContext.postPageExpandChange(itemNodeId, runtimeContext.expanded.has(itemNodeId));
-  }
-  if (shouldPatchTree) {
-    runtimeContext.patchPageTreeAfterRuntimeState(
-      Array.isArray(result.expandedIds) ? [itemNodeId, ...result.expandedIds] : [itemNodeId],
-      result.focusedId || runtimeContext.getFocusedNodeId(),
-    );
-  }
-  return shouldPatchTree;
-}
-
 function startTreeShellRuntime() {
   const stateElement = document.getElementById("tree-shell-state");
   const appElement = document.getElementById("tree-shell-app");
diff --git a/rust/crates/mnote-web/src/routes/mod.rs b/rust/crates/mnote-web/src/routes/mod.rs
index 8cff99d1..9d18d845 100644
--- a/rust/crates/mnote-web/src/routes/mod.rs
+++ b/rust/crates/mnote-web/src/routes/mod.rs
@@ -166,6 +166,10 @@ pub fn build_router(state: AppState) -> Router {
             "/api/mnote-browser-runtime/tree-shell-runtime.js",
             get(web_shell::tree_shell_runtime_asset),
         )
+        .route(
+            "/api/mnote-browser-runtime/tree-shell-page-runtime.js",
+            get(web_shell::tree_shell_page_runtime_asset),
+        )
         .route(
             "/api/mnote-browser-runtime/document-conflict-panel-runtime.js",
             get(web_shell::document_conflict_panel_runtime_asset),
@@ -617,6 +621,7 @@ mod tests {
             "/api/mnote-browser-runtime/sidebar-tree-runtime.js",
             "/api/mnote-browser-runtime/tree-live-controller.js",
             "/api/mnote-browser-runtime/tree-shell-runtime.js",
+            "/api/mnote-browser-runtime/tree-shell-page-runtime.js",
             "/api/mnote-browser-runtime/document-conflict-panel-runtime.js",
             "/api/mnote-browser-runtime/document-pane-runtime.js",
             "/api/mnote-browser-runtime/document-mindmap-host-runtime.js",
diff --git a/rust/crates/mnote-web/src/routes/web_shell.rs b/rust/crates/mnote-web/src/routes/web_shell.rs
index 48edf165..fbfc751c 100644
--- a/rust/crates/mnote-web/src/routes/web_shell.rs
+++ b/rust/crates/mnote-web/src/routes/web_shell.rs
@@ -938,6 +938,20 @@ pub async fn tree_shell_runtime_asset() -> Response {
         .unwrap_or_else(|_| Response::new(Body::empty()))
 }
 
+pub async fn tree_shell_page_runtime_asset() -> Response {
+    const JS: &str = include_str!("../../browser/tree-shell-page-runtime.js");
+    Response::builder()
+        .status(StatusCode::OK)
+        .header(
+            header::CONTENT_TYPE,
+            "application/javascript; charset=utf-8",
+        )
+        .header(header::CACHE_CONTROL, "no-store")
+        .header(HEADER_MNOTE_WEB_OWNER, "mnote-web")
+        .body(Body::from(JS))
+        .unwrap_or_else(|_| Response::new(Body::empty()))
+}
+
 pub async fn document_conflict_panel_runtime_asset() -> Response {
     // include_str! 路径相对于当前源文件 (src/routes/web_shell.rs -> ../../browser/)
     const JS: &str = include_str!("../../browser/document-conflict-panel-runtime.js");