fix: handle non-ISO-8859-1 characters in fetch headers and Content-Disposition (#1673)

* fix: handle non-ISO-8859-1 characters in fetch headers and Content-Disposition

Browser Headers API rejects characters above U+00FF. The x-opencode-directory header carries raw filesystem paths, which breaks when paths contain Chinese/CJK characters. Also fixes Content-Disposition for non-ASCII filenames per RFC 5987.

* refactor: export header sanitization helpers, deduplicate, add tests

Export isLatin1Safe and sanitizeHeadersForBrowser from runtime-fetch.ts so VS Code webview can import them instead of duplicating the logic. Add tests: isLatin1Safe boundary checks, sanitizeHeadersForBrowser encoding/deduplication, runtimeFetch round-trip encode/decode, and Content-Disposition RFC 5987 output for both ASCII and non-ASCII filenames.

* fix: mark encoded directory headers

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/web/server/lib/fs/routes.js

@@ -883,7 +883,13 @@ export const registerFsRoutes = (app, dependencies) => {
       const download = req.query.download === 'true';
       if (download) {
         const fileName = path.basename(canonicalPath);
-        res.setHeader('Content-Disposition', `attachment; filename="${fileName}"`);
+        // RFC 5987: use filename*= for non-ASCII filenames, with ASCII-only
+        // filename= as fallback for older clients.
+        const asciiOnly = fileName.replace(/[^\u0000-\u007F]/g, '');
+        const fallback = asciiOnly || 'file';
+        // Percent-encode the raw UTF-8 bytes for filename*=
+        const encoded = encodeURIComponent(fileName);
+        res.setHeader('Content-Disposition', `attachment; filename="${fallback}"; filename*=UTF-8''${encoded}`);
       }
 
       const content = await fsPromises.readFile(canonicalPath);

packages/web/server/lib/fs/routes.test.js

@@ -596,3 +596,42 @@ describe('fs exec git-read cache', () => {
     expect(calls.length).toBe(afterFill + 2);
   });
 });
+
+describe('fs raw download Content-Disposition', () => {
+  it('uses RFC 5987 filename*= encoding for non-ASCII filenames on download', async () => {
+    const fsPromises = {
+      realpath: vi.fn(async (targetPath) => targetPath),
+      stat: vi.fn(async () => ({ isFile: () => true, size: 6 })),
+      readFile: vi.fn(async () => Buffer.from('content')),
+    };
+    const handler = registerRaw(fsPromises);
+
+    const res = await callRaw(handler, {
+      path: '/repo/文件.txt',
+      download: 'true',
+    });
+
+    expect(res.statusCode).toBe(200);
+    const cd = res.getHeader('content-disposition');
+    expect(cd).toContain("filename*=UTF-8''");
+    expect(cd).toContain(encodeURIComponent('文件.txt'));
+    // ASCII fallback strips non-ASCII chars, leaving extension
+    expect(cd).toContain('filename=".txt"');
+  });
+
+  it('uses plain filename for ASCII-only filenames on download', async () => {
+    const fsPromises = {
+      realpath: vi.fn(async (targetPath) => targetPath),
+      stat: vi.fn(async () => ({ isFile: () => true, size: 6 })),
+      readFile: vi.fn(async () => Buffer.from('content')),
+    };
+    const handler = registerRaw(fsPromises);
+
+    const res = await callRaw(handler, { path: '/repo/readme.txt', download: 'true' });
+
+    expect(res.statusCode).toBe(200);
+    const cd = res.getHeader('content-disposition');
+    expect(cd).toContain('filename="readme.txt"');
+    expect(cd).toContain("filename*=UTF-8''readme.txt");
+  });
+});

packages/web/server/lib/opencode/project-directory-runtime.js

@@ -1,5 +1,13 @@
 import { createRealpathCache } from '../path-realpath-cache.js';
 
+// Browser transport percent-encodes directory hints and marks them explicitly.
+// Only marked values are decoded so literal percent sequences from direct API
+// clients are preserved.
+const safeDecodeMarkedURIComponent = (value, encoding) => {
+  if (encoding !== 'uri') return value;
+  try { return decodeURIComponent(value); } catch { return value; }
+};
+
 export const createProjectDirectoryRuntime = (dependencies) => {
   const {
     fsPromises,
@@ -50,7 +58,9 @@ export const createProjectDirectoryRuntime = (dependencies) => {
   };
 
   const resolveProjectDirectory = async (req) => {
-    const headerDirectory = typeof req.get === 'function' ? req.get('x-opencode-directory') : null;
+    const rawHeaderDirectory = typeof req.get === 'function' ? req.get('x-opencode-directory') : null;
+    const headerEncoding = typeof req.get === 'function' ? req.get('x-opencode-directory-encoding') : null;
+    const headerDirectory = rawHeaderDirectory ? safeDecodeMarkedURIComponent(rawHeaderDirectory, headerEncoding) : null;
     const queryDirectory = Array.isArray(req.query?.directory)
       ? req.query.directory[0]
       : req.query?.directory;
@@ -103,7 +113,9 @@ export const createProjectDirectoryRuntime = (dependencies) => {
   };
 
   const resolveOptionalProjectDirectory = async (req) => {
-    const headerDirectory = typeof req.get === 'function' ? req.get('x-opencode-directory') : null;
+    const rawHeaderDirectory = typeof req.get === 'function' ? req.get('x-opencode-directory') : null;
+    const headerEncoding = typeof req.get === 'function' ? req.get('x-opencode-directory-encoding') : null;
+    const headerDirectory = rawHeaderDirectory ? safeDecodeMarkedURIComponent(rawHeaderDirectory, headerEncoding) : null;
     const queryDirectory = Array.isArray(req.query?.directory)
       ? req.query.directory[0]
       : req.query?.directory;

packages/web/server/lib/opencode/project-directory-runtime.test.js

@@ -128,6 +128,58 @@ describe('project directory runtime', () => {
       expect(result).toEqual({ directory: '/real/workspace/project', error: null });
     });
 
+    it('decodes marked x-opencode-directory header values', async () => {
+      const pathWithUnicode = '/home/user/测试项目';
+      let validatedPath = null;
+      const runtime = createTestRuntime({
+        fsPromises: {
+          stat: async (p) => {
+            validatedPath = p;
+            return { isDirectory: () => true };
+          },
+          realpath: async (p) => p,
+        },
+      });
+
+      const req = {
+        get: (header) => {
+          if (header === 'x-opencode-directory') return encodeURIComponent(pathWithUnicode);
+          if (header === 'x-opencode-directory-encoding') return 'uri';
+          return null;
+        },
+        query: {},
+      };
+
+      const result = await runtime.resolveProjectDirectory(req);
+
+      expect(validatedPath).toBe(pathWithUnicode);
+      expect(result).toEqual({ directory: pathWithUnicode, error: null });
+    });
+
+    it('preserves raw percent sequences without directory encoding marker', async () => {
+      const rawPath = '/home/user/foo%20bar';
+      let validatedPath = null;
+      const runtime = createTestRuntime({
+        fsPromises: {
+          stat: async (p) => {
+            validatedPath = p;
+            return { isDirectory: () => true };
+          },
+          realpath: async (p) => p,
+        },
+      });
+
+      const req = {
+        get: (header) => header === 'x-opencode-directory' ? rawPath : null,
+        query: {},
+      };
+
+      const result = await runtime.resolveProjectDirectory(req);
+
+      expect(validatedPath).toBe(rawPath);
+      expect(result).toEqual({ directory: rawPath, error: null });
+    });
+
     it('resolves symlinks in query directory parameter', async () => {
       const runtime = createTestRuntime({
         fsPromises: {
@@ -222,5 +274,29 @@ describe('project directory runtime', () => {
 
       expect(result).toEqual({ directory: '/real/workspace/project', error: null });
     });
+
+    it('preserves raw percent sequences without directory encoding marker', async () => {
+      const rawPath = '/optional/foo%25bar';
+      let validatedPath = null;
+      const runtime = createTestRuntime({
+        fsPromises: {
+          stat: async (p) => {
+            validatedPath = p;
+            return { isDirectory: () => true };
+          },
+          realpath: async (p) => p,
+        },
+      });
+
+      const req = {
+        get: (header) => header === 'x-opencode-directory' ? rawPath : null,
+        query: {},
+      };
+
+      const result = await runtime.resolveOptionalProjectDirectory(req);
+
+      expect(validatedPath).toBe(rawPath);
+      expect(result).toEqual({ directory: rawPath, error: null });
+    });
   });
 });