fix: strip hidden unicode from imported context

src/core/unicode-safety.test.ts

@@ -0,0 +1,12 @@
+import { describe, expect, it } from "vitest";
+import { hasHiddenUnicode, stripHiddenUnicode } from "./unicode-safety.js";
+
+describe("unicode safety", () => {
+  it("strips hidden instruction carriers", () => {
+    const tag = String.fromCodePoint(0xe0069);
+    const text = `safe${tag}\u200b\u202etext`;
+
+    expect(hasHiddenUnicode(text)).toBe(true);
+    expect(stripHiddenUnicode(text)).toBe("safetext");
+  });
+});

src/core/unicode-safety.ts

@@ -0,0 +1,11 @@
+const HIDDEN_UNICODE = /[\u200B-\u200F\u202A-\u202E\u2060-\u206F\uFE00-\uFE0F\u{E0000}-\u{E007F}]/gu;
+
+export function stripHiddenUnicode(text: string): string {
+  // ponytail: strips known invisible instruction carriers; add reporting metadata if UI needs forensics.
+  return text.replace(HIDDEN_UNICODE, "");
+}
+
+export function hasHiddenUnicode(text: string): boolean {
+  HIDDEN_UNICODE.lastIndex = 0;
+  return HIDDEN_UNICODE.test(text);
+}

src/pai/pai-connector.ts

@@ -1,6 +1,7 @@
 import * as fs from "node:fs";
 import * as path from "node:path";
 import * as os from "node:os";
+import { stripHiddenUnicode } from "../core/unicode-safety.js";
 
 const PAI_ROOT = path.join(os.homedir(), ".claude", "PAI");
 
@@ -55,7 +56,7 @@ export class PaiConnector {
         return {
           path: full,
           name: f.replace(/\.md$/, ""),
-          content: fs.readFileSync(full, "utf-8"),
+          content: stripHiddenUnicode(fs.readFileSync(full, "utf-8")),
         };
       });
   }
@@ -70,7 +71,7 @@ export class PaiConnector {
         return fs.statSync(skillPath).isDirectory() && fs.existsSync(path.join(skillPath, "SKILL.md"));
       }).map((f) => {
         const skillPath = path.join(legacyDir, f);
-        const skillMd = fs.readFileSync(path.join(skillPath, "SKILL.md"), "utf-8");
+        const skillMd = stripHiddenUnicode(fs.readFileSync(path.join(skillPath, "SKILL.md"), "utf-8"));
         const desc = skillMd.split("\n").slice(0, 5).join(" ").slice(0, 200);
         return { name: f, path: skillPath, description: desc };
       });
@@ -81,7 +82,7 @@ export class PaiConnector {
       return fs.statSync(skillPath).isDirectory() && fs.existsSync(path.join(skillPath, "SKILL.md"));
     }).map((f) => {
       const skillPath = path.join(skillsDir, f);
-      const skillMd = fs.readFileSync(path.join(skillPath, "SKILL.md"), "utf-8");
+      const skillMd = stripHiddenUnicode(fs.readFileSync(path.join(skillPath, "SKILL.md"), "utf-8"));
       const desc = skillMd.split("\n").slice(0, 5).join(" ").slice(0, 200);
       return { name: f, path: skillPath, description: desc };
     });
@@ -107,7 +108,7 @@ export class PaiConnector {
     if (isaFiles.length === 0) return null;
 
     const latest = isaFiles.sort((a, b) => b.name.localeCompare(a.name))[0];
-    const content = fs.readFileSync(latest.path, "utf-8");
+    const content = stripHiddenUnicode(fs.readFileSync(latest.path, "utf-8"));
     const sections = this.parseSections(content);
 
     return { path: latest.path, name: latest.name, content, sections };
@@ -116,7 +117,7 @@ export class PaiConnector {
   readFile(relativePath: string): string | null {
     const full = path.join(this.paiRoot, relativePath);
     if (!fs.existsSync(full)) return null;
-    return fs.readFileSync(full, "utf-8");
+    return stripHiddenUnicode(fs.readFileSync(full, "utf-8"));
   }
 
   private parseSections(content: string): Map<string, string> {

src/pai/skill-sync.ts

@@ -3,6 +3,7 @@ import * as path from "node:path";
 import * as os from "node:os";
 import type { SkillDefinition, SkillStep } from "../core/types.js";
 import { StateStore } from "../core/state-store.js";
+import { stripHiddenUnicode } from "../core/unicode-safety.js";
 
 const PAI_SKILLS_DIR = path.join(os.homedir(), ".claude", "skills");
 
@@ -31,7 +32,7 @@ export class SkillSync {
       const skillMd = path.join(this.paiSkillsDir, entry.name, "SKILL.md");
       if (!fs.existsSync(skillMd)) continue;
 
-      const content = fs.readFileSync(skillMd, "utf-8");
+      const content = stripHiddenUnicode(fs.readFileSync(skillMd, "utf-8"));
       const description = this.extractDescription(content);
       const steps = this.extractSteps(content);
       const tags = this.extractTags(content);
@@ -118,7 +119,7 @@ export class SkillSync {
     const skillPath = path.join(this.paiSkillsDir, skillName, "SKILL.md");
     if (!fs.existsSync(skillPath)) return null;
 
-    let content = fs.readFileSync(skillPath, "utf-8");
+    let content = stripHiddenUnicode(fs.readFileSync(skillPath, "utf-8"));
 
     // Find or create a Lessons Learned section
     const lessonsHeader = "## Lessons Learned";