diff --git a/bugs/05-editor-mainline/done/5-43-large-json-resource-tab-freeze-v1.md b/bugs/05-editor-mainline/done/5-43-large-json-resource-tab-freeze-v1.md
new file mode 100644
index 00000000..a25dfb61
--- /dev/null
+++ b/bugs/05-editor-mainline/done/5-43-large-json-resource-tab-freeze-v1.md
@@ -0,0 +1,47 @@
+# 5-43 大 JSON 资源 tab 打开后卡死且无法关闭
+
+## 状态
+
+- 状态：done
+- owner：05-editor-mainline
+- 发现时间：2026-06-04
+- 修复时间：2026-06-04
+
+## 现象
+
+在 local-folder 文件树中打开 OCR sidecar 的 source-map JSON，例如：
+
+- `/mnt/Data1T/research/DHA_cosmetics/literature/SCCS_1612_19_DHA.ocr/SCCS_1612_19_DHA.pdf.source-map.json`
+
+页面会把 JSON 当作可编辑 code 资源加载进 Tiptap resource tab。大 JSON 打开后主线程明显卡顿，标签页关闭按钮无响应或被资源编辑 session 的关闭保护阻止；其它普通资源 tab 仍可关闭。
+
+## 根因
+
+`document-resource-tab-runtime.js` 将 `.json` 归类为 `code`，并且 `markdown/text/code` 统一走 `openTiptapResourceTab`。这会为 JSON 创建完整 Tiptap 编辑 session、序列化大文档、挂本地文件事件 channel，并把 code 资源纳入 dirty close guard。
+
+OCR source-map JSON 是机器生成的只读索引文件，不适合作为页面编辑器文档打开；大文件走 Tiptap 会放大渲染和关闭保护成本。
+
+## 修复
+
+- `code` 资源不再声明为 editable。
+- `.json` 等 code 资源改走轻量只读 `<pre><code>` 预览，不创建 Tiptap editor session。
+- 只读预览显示文件大小，超过预览上限时截断提示。
+- Markdown 和普通 text resource tab 仍保留原可编辑 Tiptap 路径。
+
+## 验证
+
+- `node --check rust/crates/mnote-web/browser/document-resource-tab-runtime.js`
+- `cargo build -p mnote-web --manifest-path rust/Cargo.toml`
+- 临时启动 `127.0.0.1:3023` 后用 Playwright 打开真实页面：
+  - `rootUri=file:///mnt/Data1T/research/DHA_cosmetics`
+  - 页面：`literature/dha_computational_modeling_literature.md`
+  - 资源：`literature/SCCS_1612_19_DHA.ocr/SCCS_1612_19_DHA.pdf.source-map.json`
+- 浏览器验证结果：
+  - resource tab 成功打开只读 code preview。
+  - 当前 panel 不存在 `mnote-leptos-tiptap-island-editor-root`，证明没有挂 Tiptap 编辑器。
+  - 预览加载 `970708` 字符，meta 显示 `只读预览 · 971,098 bytes`。
+  - 点击 tab close 后 `openResourcePanels=0`，主页面 tab 恢复选中。
+
+## 备注
+
+`task505-resource-tab-watch-contract-smoke.js` 在本次临时 standalone 服务上未通过，失败点是 Markdown resource 外部文件变更 watcher 未把写盘更新同步回 resource editor；该路径与本次 JSON 只读预览不同，未作为本 bug 验收条件。
diff --git a/rust/crates/mnote-web/browser/document-resource-tab-runtime.js b/rust/crates/mnote-web/browser/document-resource-tab-runtime.js
index 11012f73..835c4589 100644
--- a/rust/crates/mnote-web/browser/document-resource-tab-runtime.js
+++ b/rust/crates/mnote-web/browser/document-resource-tab-runtime.js
@@ -64,6 +64,7 @@ export const createResourceTabRuntime = (dependencies = {}) => {
   const resourceTabRegistry = new Map();
   const resourceTabMru = { primary: [], secondary: [] };
   const resourceTabMruMax = 20;
+  const readonlyCodePreviewMaxChars = 1_500_000;
   const resourceTabCloseGuardAttribute = 'data-resource-tab-close-guarded';
   let onlyofficeBridgeReadyListenerBound = false;
 
@@ -263,7 +264,7 @@ export const createResourceTabRuntime = (dependencies = {}) => {
     const badgeKind = resourceTabBadgeKind(input, kind);
     const rawTarget = String(input?.openTarget || '').trim().toLowerCase();
     const openTarget = rawTarget === 'new-window' || rawTarget === 'side' ? rawTarget : 'active-tab';
-    const editable = kind === 'markdown' || kind === 'text' || kind === 'code';
+    const editable = kind === 'markdown' || kind === 'text';
     const defaultOpenMode = kind === 'office' && openTarget === 'active-tab' ? 'active-tab-iframe' : openTarget;
     const viewerUrl = kind === 'office'
       ? String(input?.officeUrl || input?.href || '').trim()
@@ -2064,6 +2065,46 @@ export const createResourceTabRuntime = (dependencies = {}) => {
     markIntendedSlashRoot(entry);
   };
 
+  const openReadonlyCodeResourceTab = async (entry, input) => {
+    entry.panel.innerHTML = '';
+    const shell = document.createElement('div');
+    shell.className = 'mnote-resource-tab-code-shell';
+    shell.setAttribute('data-mnote-resource-readonly-preview', 'true');
+
+    const header = document.createElement('div');
+    header.className = 'mnote-resource-tab-code-header';
+    const title = document.createElement('div');
+    title.className = 'mnote-resource-tab-code-title';
+    title.textContent = entry.title;
+    const meta = document.createElement('div');
+    meta.className = 'mnote-resource-tab-code-meta';
+    meta.textContent = '只读预览';
+    header.append(title, meta);
+
+    const pre = document.createElement('pre');
+    pre.className = 'mnote-resource-tab-code-preview';
+    const code = document.createElement('code');
+    pre.append(code);
+    shell.append(header, pre);
+    entry.panel.append(shell);
+
+    const response = await fetch(localResourceReadUrl(input.rootUri, input.path), { cache: 'no-store', headers: { accept: 'application/json' } });
+    const payload = await response.json().catch(() => null);
+    if (!response.ok || !payload || payload.ok !== true) throw new Error(payload?.error?.message || `resource_read_failed_${response.status}`);
+    const readResult = payload.result || {};
+    const rawText = typeof readResult.text === 'string' ? readResult.text : '';
+    const truncated = rawText.length > readonlyCodePreviewMaxChars;
+    code.textContent = truncated
+      ? `${rawText.slice(0, readonlyCodePreviewMaxChars)}\n\n/* 预览已截断，文件过大，请用外部编辑器查看完整内容。 */`
+      : rawText;
+    const fileSize = new Blob([rawText]).size;
+    meta.textContent = truncated
+      ? `只读预览 · 已截断 · ${fileSize.toLocaleString()} bytes`
+      : `只读预览 · ${fileSize.toLocaleString()} bytes`;
+    entry.session = null;
+    entry.view = null;
+  };
+
   const ensureOnlyofficeBridgeReadyListener = () => {
     if (onlyofficeBridgeReadyListenerBound) return;
     onlyofficeBridgeReadyListenerBound = true;
@@ -2245,8 +2286,10 @@ export const createResourceTabRuntime = (dependencies = {}) => {
     try {
       if (entry.kind === 'mindmap') {
         await openMindmapResourceTab(entry, input);
-      } else if (entry.kind === 'markdown' || entry.kind === 'text' || entry.kind === 'code') {
+      } else if (entry.kind === 'markdown' || entry.kind === 'text') {
         await openTiptapResourceTab(entry, input);
+      } else if (entry.kind === 'code') {
+        await openReadonlyCodeResourceTab(entry, input);
       } else {
         await openPassiveResourceTab(entry, input);
       }
diff --git a/rust/crates/mnote-web/src/ssr/styles.rs b/rust/crates/mnote-web/src/ssr/styles.rs
index 9f7143dd..0582e3c4 100644
--- a/rust/crates/mnote-web/src/ssr/styles.rs
+++ b/rust/crates/mnote-web/src/ssr/styles.rs
@@ -2938,6 +2938,56 @@ body {
   padding: 34px 48px;
 }
 
+.mnote-resource-tab-code-shell {
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  min-height: calc(100vh - 80px);
+  background: #FFF;
+  color: #37352F;
+}
+
+.mnote-resource-tab-code-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 16px;
+  height: 42px;
+  padding: 0 18px;
+  border-bottom: 1px solid rgba(55, 53, 47, 0.1);
+  background: #FAFAF8;
+  box-sizing: border-box;
+}
+
+.mnote-resource-tab-code-title {
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  font-size: 13px;
+  font-weight: 600;
+}
+
+.mnote-resource-tab-code-meta {
+  flex: 0 0 auto;
+  font-size: 12px;
+  color: #73726E;
+}
+
+.mnote-resource-tab-code-preview {
+  flex: 1 1 auto;
+  min-height: 0;
+  margin: 0;
+  padding: 18px 22px 48px;
+  overflow: auto;
+  background: #1F2328;
+  color: #F0F3F6;
+  font: 12px/1.6 ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
+  white-space: pre;
+  tab-size: 2;
+  box-sizing: border-box;
+}
+
 .mnote-resource-tab-error {
   display: flex;
   place-items: center;