fix(security): keep Unicode generation offline

CHANGELOG.md

@@ -12,8 +12,8 @@ is published under the public `@bidilens` npm scope.
   preserving `$...$`, `$$...$$`, `$$$$`, and `\(...\)` recognition.
 - Expressed UTF-16-to-code-point range construction with bounded typed-array
   fills so input-derived offsets cannot be interpreted as object properties.
-- Restricted downloaded Unicode data writes to the two repository-owned,
-  version-pinned destination paths after exact SHA-256 verification.
+- Removed the generator's network-to-filesystem refresh mode; Unicode table
+  generation now reads only two vendored, version- and SHA-256-pinned files.
 
 ### Direction correctness
 

docs/SECURITY.md

@@ -44,9 +44,8 @@ pops/openers, formatting that crosses an isolate boundary, and U+200B.
 - recursive CLI scanning skips symbolic links.
 - raw-text math delimiter discovery is a single forward scan; repeated
   unmatched delimiters cannot trigger polynomial regular-expression work.
-- the optional Unicode download command accepts only two source/destination
-  pairs pinned in repository code and verifies each exact SHA-256 before a
-  write; untrusted text never reaches that build-time path.
+- Unicode generation is offline-only: it reads two vendored, SHA-256-pinned
+  source files and exposes no network-to-filesystem refresh path.
 
 ## False-positive policy
 

package.json

@@ -44,7 +44,6 @@
     "build:visual-fixtures": "pnpm --filter @bidilens/core run build && pnpm --filter @bidilens/markdown run build && pnpm --filter @bidilens/react run build && pnpm --filter @bidilens/web-component run build",
     "test:visual": "pnpm run build:visual-fixtures && playwright test",
     "unicode:generate": "tsx scripts/generate-bidi-data.ts",
-    "unicode:download": "tsx scripts/generate-bidi-data.ts --download",
     "unicode:check": "tsx scripts/generate-bidi-data.ts --check",
     "release:check": "tsx scripts/release-check.ts",
     "android:check": "tsx scripts/run-android.ts",

scripts/generate-bidi-data.ts

@@ -40,8 +40,6 @@ const UNICODE_SOURCES = [
   }
 ] as const satisfies readonly UnicodeSource[];
 
-const PINNED_UNICODE_PATHS = new Set(UNICODE_SOURCES.map((source) => source.path));
-
 const CLASS = {
   L: 0,
   R: 1,
@@ -270,36 +268,24 @@ ${renderRustRanges('NATURAL_LETTER_RANGES', ranges.naturalLetters)}
 `;
 }
 
-async function sourceBytes(source: UnicodeSource, download: boolean): Promise<Uint8Array> {
-  let bytes: Uint8Array;
-  if (download) {
-    const response = await fetch(source.url);
-    if (!response.ok) throw new Error(`${source.label} download failed: HTTP ${response.status}`);
-    bytes = new Uint8Array(await response.arrayBuffer());
-  } else {
-    bytes = await readFile(source.path);
-  }
+function verifiedBytes(source: UnicodeSource, bytes: Uint8Array): Uint8Array {
   const actualSha256 = createHash('sha256').update(bytes).digest('hex');
   if (actualSha256 !== source.sha256) {
     throw new Error(`${source.label} checksum mismatch: expected ${source.sha256}, received ${actualSha256}`);
   }
-  if (download) {
-    if (!PINNED_UNICODE_PATHS.has(source.path)) {
-      throw new Error(`Refusing to write outside the pinned Unicode source paths: ${source.path}`);
-    }
-    await mkdir(dirname(source.path), { recursive: true });
-    await writeFile(source.path, bytes);
-  }
   return bytes;
 }
 
+async function localSourceBytes(source: UnicodeSource): Promise<Uint8Array> {
+  return verifiedBytes(source, await readFile(source.path));
+}
+
 async function main(): Promise<void> {
-  const download = process.argv.includes('--download');
   const check = process.argv.includes('--check');
   const [bidiSource, generalCategorySource] = UNICODE_SOURCES;
   const [bidiBytes, generalCategoryBytes] = await Promise.all([
-    sourceBytes(bidiSource, download),
-    sourceBytes(generalCategorySource, download)
+    localSourceBytes(bidiSource),
+    localSourceBytes(generalCategorySource)
   ]);
   const ranges = collectGeneratedRanges(
     new TextDecoder().decode(bidiBytes),

unicode/README.md

@@ -21,11 +21,14 @@ To reproduce the generated table from the vendored source:
 pnpm unicode:generate
 ```
 
-To deliberately refresh the pinned upstream file, first update the version,
-URLs, and both expected SHA-256 values in `scripts/generate-bidi-data.ts`, then run:
+To deliberately refresh the pinned upstream files, download both exact source
+URLs shown in `scripts/generate-bidi-data.ts` outside this repository, verify
+their expected SHA-256 values, replace only the two vendored files, then update
+the version and hashes in the generator. The generator deliberately has no
+network-to-filesystem mode. Review with:
 
 ```bash
-pnpm unicode:download
+pnpm unicode:generate
 git diff -- unicode packages/core/src/generated/bidi-ranges.ts
 pnpm run check
 ```