Skip claude.ai/code and use word boundaries for mappings

Two user-reported conflicts when using the extension alongside Claude
Code on the web and with short mappings:

1. Claude Code (claude.ai/code) sends real file paths, usernames, and
   shell commands to its tool runtime. Substituting any of these
   corrupts execution, forcing users to disable the extension for that
   app. early-hook.js and injector.js now short-circuit on that path so
   fetch/XHR are never wrapped and no page-world script is injected.

2. Explicit mappings used raw literal regexes, so "not" -> "bad" would
   rewrite "nothing" into "badhing". substitute/reveal/scan/diff (and
   their page-world mirrors) now add \b on word-character edges only,
   leaving non-word edges like "@foo" unchanged so they keep matching.

https://claude.ai/code/session_01Y2YprLMx348eWD5C9Z4zpV

src/content/content.js

@@ -51,8 +51,8 @@
 
     for (const m of sorted) {
       if (!m.enabled || !m.real?.trim() || !m.substitute?.trim()) continue;
-      const escaped = esc(m.real);
+      const pattern = wordBoundary(m.real);
-      const regex = new RegExp(escaped, m.caseSensitive ? 'g' : 'gi');
+      const regex = new RegExp(pattern, m.caseSensitive ? 'g' : 'gi');
       let match;
       while ((match = regex.exec(result)) !== null) {
         replacements.push({
@@ -71,8 +71,8 @@
     const sorted = [...maps].sort((a, b) => b.substitute.length - a.substitute.length);
     for (const m of sorted) {
       if (!m.enabled || !m.real?.trim() || !m.substitute?.trim()) continue;
-      const escaped = esc(m.substitute);
+      const pattern = wordBoundary(m.substitute);
-      const regex = new RegExp(escaped, m.caseSensitive ? 'g' : 'gi');
+      const regex = new RegExp(pattern, m.caseSensitive ? 'g' : 'gi');
       result = result.replace(regex, m.real);
     }
     return result;
@@ -82,6 +82,15 @@
     return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
   }
 
+  // Add \b only on word-character edges so "not" doesn't match inside "nothing",
+  // while leaving non-word edges (e.g. "@foo") alone since they self-delimit.
+  function wordBoundary(str) {
+    const escaped = esc(str);
+    const left = /^\w/.test(str) ? '\\b' : '';
+    const right = /\w$/.test(str) ? '\\b' : '';
+    return left + escaped + right;
+  }
+
   // ============================================================
   // Smart Pattern Engine (inline for page world)
   // ============================================================
@@ -1043,8 +1052,8 @@
     const pairs = getRevealPairs();
     let result = text;
     for (const p of pairs) {
-      const escaped = esc(p.from);
+      const pattern = wordBoundary(p.from);
-      const regex = new RegExp(escaped, p.caseSensitive ? 'g' : 'gi');
+      const regex = new RegExp(pattern, p.caseSensitive ? 'g' : 'gi');
       result = result.replace(regex, p.to);
     }
     return result;
@@ -1085,9 +1094,9 @@
     const pairs = getRevealPairs();
     let result = text;
     for (const p of pairs) {
-      const escaped = esc(p.to);   // p.to is the real value
+      const pattern = wordBoundary(p.to);
-      const regex = new RegExp(escaped, p.caseSensitive ? 'g' : 'gi');
+      const regex = new RegExp(pattern, p.caseSensitive ? 'g' : 'gi');
-      result = result.replace(regex, p.from);  // p.from is the substitute
+      result = result.replace(regex, p.from);
     }
     return result;
   }

src/content/early-hook.js

@@ -9,6 +9,17 @@
  * because sites like claude.ai have strict CSP that blocks inline scripts.
  */
 (function () {
+  // Claude Code (web) runs at claude.ai/code and makes tool-call requests
+  // containing real file paths, usernames, and commands. Substituting any of
+  // these corrupts tool execution, so we never hook fetch/XHR on that app.
+  if (
+    location.hostname === 'claude.ai' &&
+    /^\/code(\/|$)/.test(location.pathname)
+  ) {
+    window.__ssSkipHost = true;
+    return;
+  }
+
   window.__ssOriginalFetch = window.fetch;
   window.__ssOriginalXHROpen = XMLHttpRequest.prototype.open;
   window.__ssOriginalXHRSend = XMLHttpRequest.prototype.send;

src/content/injector.js

@@ -15,6 +15,15 @@
   if (window.__silentSendInjected) return;
   window.__silentSendInjected = true;
 
+  // Skip Claude Code (web). Its tool-call traffic carries real paths/commands
+  // that must reach the runtime verbatim — substitution breaks execution.
+  if (
+    location.hostname === 'claude.ai' &&
+    /^\/code(\/|$)/.test(location.pathname)
+  ) {
+    return;
+  }
+
   // Merge active profiles into flat identity object
   function mergeProfiles(data) {
     const profiles = data?.profiles || [];

src/lib/substitution-engine.js

@@ -23,8 +23,8 @@ const SubstitutionEngine = {
     for (const mapping of sorted) {
       if (!mapping.enabled || !mapping.real?.trim() || !mapping.substitute?.trim()) continue;
 
-      const escaped = this._escapeRegex(mapping.real);
+      const pattern = this._wordBoundaryPattern(mapping.real);
-      const regex = new RegExp(escaped, mapping.caseSensitive ? 'g' : 'gi');
+      const regex = new RegExp(pattern, mapping.caseSensitive ? 'g' : 'gi');
       let match;
 
       while ((match = regex.exec(result)) !== null) {
@@ -56,8 +56,8 @@ const SubstitutionEngine = {
     for (const mapping of sorted) {
       if (!mapping.enabled || !mapping.real?.trim() || !mapping.substitute?.trim()) continue;
 
-      const escaped = this._escapeRegex(mapping.substitute);
+      const pattern = this._wordBoundaryPattern(mapping.substitute);
-      const regex = new RegExp(escaped, mapping.caseSensitive ? 'g' : 'gi');
+      const regex = new RegExp(pattern, mapping.caseSensitive ? 'g' : 'gi');
       result = result.replace(regex, mapping.real);
     }
 
@@ -73,8 +73,8 @@ const SubstitutionEngine = {
     for (const mapping of mappings) {
       if (!mapping.enabled || !mapping.real?.trim()) continue;
 
-      const escaped = this._escapeRegex(mapping.real);
+      const pattern = this._wordBoundaryPattern(mapping.real);
-      const regex = new RegExp(escaped, mapping.caseSensitive ? 'g' : 'gi');
+      const regex = new RegExp(pattern, mapping.caseSensitive ? 'g' : 'gi');
 
       if (regex.test(text)) {
         found.push({
@@ -105,8 +105,8 @@ const SubstitutionEngine = {
     for (const mapping of sorted) {
       if (!mapping.enabled || !mapping.real?.trim() || !mapping.substitute?.trim()) continue;
 
-      const escaped = this._escapeRegex(mapping.real);
+      const pattern = this._wordBoundaryPattern(mapping.real);
-      const regex = new RegExp(escaped, mapping.caseSensitive ? 'g' : 'gi');
+      const regex = new RegExp(pattern, mapping.caseSensitive ? 'g' : 'gi');
       let match;
 
       while ((match = regex.exec(original)) !== null) {
@@ -145,6 +145,16 @@ const SubstitutionEngine = {
   _escapeRegex(str) {
     return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
   },
+
+  // Wrap an escaped literal in \b only on edges that are word characters,
+  // so "not" → "bad" matches "not" but not "nothing", while mappings whose
+  // edges aren't word chars (e.g. "@foo", "foo.com ") still work.
+  _wordBoundaryPattern(str) {
+    const escaped = this._escapeRegex(str);
+    const left = /^\w/.test(str) ? '\\b' : '';
+    const right = /\w$/.test(str) ? '\\b' : '';
+    return left + escaped + right;
+  },
 };
 
 // Support both module and content-script contexts

test-suite.js

@@ -345,6 +345,18 @@ test('Disabled mapping is skipped', () => {
   if (result.text.includes('Alex Demo')) throw 'Disabled mapping should not substitute';
 });
 
+test('Mapping matches whole words only', () => {
+  const result = SubstitutionEngine.substitute('nothing is not a thing, not even this', [
+    { real: 'not', substitute: 'bad', enabled: true }
+  ]);
+  if (result.text.includes('bahing') || result.text.includes('badhing')) {
+    throw `Should not match inside "nothing", got: ${result.text}`;
+  }
+  if (!/\bbad\b/.test(result.text)) {
+    throw `Should still match standalone "not", got: ${result.text}`;
+  }
+});
+
 // ============================================================
 // SMART PATTERNS
 // ============================================================