perf: migrate chat rendering to virtua (#1651)

* refactor: migrate chat history virtualization to virtua

* refactor: render loaded chat history directly

* refactor: finish virtua migration

* perf: defer tool body rendering

* perf: queue deferred tool body mounts

* perf: quiet and defer markdown file probes

* perf: defer markdown code highlighting

* perf: stabilize markdown plugin lists

* perf: defer mermaid markdown rendering

* perf: delay markdown file reference annotation

* perf: attach markdown table listeners on demand

* perf: trim markdown render overhead

packages/vscode/src/bridge-localfs-proxy-runtime.test.js

@@ -0,0 +1,59 @@
+import { describe, expect, it, mock } from 'bun:test';
+
+mock.module('fs', () => ({
+  promises: {
+    realpath: mock(async () => {
+      const error = new Error('missing');
+      error.code = 'ENOENT';
+      throw error;
+    }),
+    stat: mock(async () => {
+      const error = new Error('missing');
+      error.code = 'ENOENT';
+      throw error;
+    }),
+  },
+  default: {
+    promises: {
+      realpath: mock(async () => {
+        const error = new Error('missing');
+        error.code = 'ENOENT';
+        throw error;
+      }),
+      stat: mock(async () => {
+        const error = new Error('missing');
+        error.code = 'ENOENT';
+        throw error;
+      }),
+    },
+  },
+}));
+
+mock.module('vscode', () => ({
+  Uri: {
+    file: (fsPath) => ({ fsPath }),
+  },
+  workspace: {
+    workspaceFolders: [{ uri: { fsPath: '/workspace' } }],
+  },
+}));
+
+const { tryHandleLocalFsProxy } = await import('./bridge-localfs-proxy-runtime');
+
+describe('bridge local fs proxy', () => {
+  it('returns a quiet optional stat miss for missing files', async () => {
+    const response = await tryHandleLocalFsProxy('GET', '/api/fs/stat?path=%2Fmissing.ts&optional=true');
+
+    expect(response?.status).toBe(200);
+    expect(JSON.parse(Buffer.from(response?.bodyBase64 ?? '', 'base64').toString('utf8'))).toEqual({
+      path: '/missing.ts',
+      exists: false,
+    });
+  });
+
+  it('keeps regular stat miss behavior without optional flag', async () => {
+    const response = await tryHandleLocalFsProxy('GET', '/api/fs/stat?path=%2Fmissing.ts');
+
+    expect(response?.status).toBe(404);
+  });
+});

packages/vscode/src/bridge-localfs-proxy-runtime.ts

@@ -65,8 +65,19 @@ export const tryHandleLocalFsProxy = async (method: string, requestPath: string)
   }
 
   const targetPath = parsed.searchParams.get('path') || '';
+  const optional = parsed.searchParams.get('optional') === 'true';
   const resolution: FsReadPathResolution = await resolveFileReadPath(targetPath);
   if (!resolution.ok) {
+    if (fsProxyPath === '/api/fs/stat' && optional && resolution.status === 404) {
+      return {
+        status: 200,
+        headers: {
+          'content-type': 'application/json',
+          'cache-control': 'no-store',
+        },
+        bodyBase64: base64EncodeUtf8(JSON.stringify({ path: targetPath, exists: false })),
+      };
+    }
     return buildProxyJsonError(resolution.status, resolution.error);
   }
 
@@ -116,6 +127,16 @@ export const tryHandleLocalFsProxy = async (method: string, requestPath: string)
   } catch (error) {
     const err = error as NodeJS.ErrnoException;
     if (err?.code === 'ENOENT') {
+      if (fsProxyPath === '/api/fs/stat' && optional) {
+        return {
+          status: 200,
+          headers: {
+            'content-type': 'application/json',
+            'cache-control': 'no-store',
+          },
+          bodyBase64: base64EncodeUtf8(JSON.stringify({ path: targetPath, exists: false })),
+        };
+      }
       return buildProxyJsonError(404, 'File not found');
     }
     if (fsProxyPath === '/api/fs/stat') {