feat: add hostname substitution in user@host patterns

jsmith@macbook-pro now becomes ademo@mycomputer when both username
and hostname are configured in the Identity tab. Hostnames are also
caught standalone (e.g. just "macbook-pro" in text).

Also rewrites README with detailed step-by-step Mozilla API key
setup instructions for Firefox signing.

https://claude.ai/code/session_01Dvgwe7XMoSxnWXkih8p1Cw

README.md

@@ -1,20 +1,37 @@
 # Silent Send
 
-A Chrome extension that intercepts personal information and substitutes it with user-defined replacements before sending to Claude.ai.
+A browser extension (Chrome + Firefox) that intercepts personal information and substitutes it with user-defined replacements before sending to Claude.ai.
 
 ## How it works
 
-1. **You define mappings** — e.g. "John Smith" → "Alex Demo", "john@gmail.com" → "alex@example.com"
-2. **You type normally** — you see your real text while composing
-3. **On send, it swaps** — the extension intercepts the API request and replaces real values with substitutes
-4. **Badge shows count** — the extension icon shows how many substitutions were made
-5. **Reveal mode** — optionally translates Claude's responses back to your real data
+1. **You fill in your Identity** — name, email, username, computer name, phone
+2. **Smart patterns auto-catch variations** — `jsmith@macbook-pro`, `John's`, `/home/jsmith`, `555.123.4567`
+3. **You type normally** — you see your real text while composing
+4. **On send, it swaps** — the extension intercepts the API request and replaces real values with substitutes
+5. **Badge shows count** — the extension icon shows how many substitutions were made
+6. **Reveal mode** — optionally translates Claude's responses back to your real data
+
+### Smart pattern examples
+
+| You type | What gets sent |
+|----------|---------------|
+| `jsmith@macbook-pro` | `ademo@mycomputer` |
+| `anyone@gmail.com` | `anon@example.com` (catch-all) |
+| `John Smith` | `Alex Demo` |
+| `Smith, John` | `Demo, Alex` |
+| `John's code` | `Alex's code` |
+| `/home/jsmith/project` | `/home/ademo/project` |
+| `~jsmith` | `~ademo` |
+| `C:\Users\jsmith` | `C:\Users\ademo` |
+| `(555) 123-4567` | `(555) 000-0000` |
+| `555.123.4567` | `(555) 000-0000` |
+| `macbook-pro` | `mycomputer` |
 
 ## How to verify it's working
 
 - **Badge count** on the extension icon shows substitutions per page
 - **Activity tab** in the popup shows a timestamped log of every substitution
-- **Test tab** in the popup lets you type text and see the before/after diff
+- **Test tab** in the popup lets you type text and see the before/after diff live
 - **Reveal mode** (eye icon) toggles showing real vs substitute data in responses
 - **Browser DevTools** → Console shows `[Silent Send] Substituted N value(s)` messages
 
@@ -29,28 +46,61 @@ A Chrome extension that intercepts personal information and substitutes it with
 6. Navigate to claude.ai — the extension is active
 
 ### Firefox (signed, persistent)
-1. Clone this repo
-2. `npm install`
-3. Get your free Mozilla API credentials at https://addons.mozilla.org/developers/addon/api/key/
-4. `cp .env.example .env` and fill in your key + secret
-5. `source .env && npm run sign:firefox`
-6. Install the `.xpi` file from `dist/firefox-signed/` — drag it into Firefox or use File → Open
-7. Navigate to claude.ai — the extension is active
 
-The signed `.xpi` is permanent — survives restarts, no store listing needed.
+Firefox requires extensions to be signed. Mozilla provides free self-hosted signing — no store listing needed.
+
+#### Step 1: Get your Mozilla API credentials
+
+1. Go to https://addons.mozilla.org/developers/addon/api/key/
+2. Sign in with a Firefox account (create one free if you don't have one)
+3. On that page you'll see two values:
+   - **JWT issuer** — looks like `user:12345678:901`
+   - **JWT secret** — a long alphanumeric string
+4. These are your API key and secret
+
+#### Step 2: Configure and sign
+
+```bash
+# Install dependencies
+npm install
+
+# Copy the env template and fill in your credentials
+cp .env.example .env
+```
+
+Edit `.env` with the values from step 1:
+```
+WEB_EXT_API_KEY="user:12345678:901"
+WEB_EXT_API_SECRET="your-jwt-secret-here"
+```
+
+Then build and sign:
+```bash
+source .env && npm run sign:firefox
+```
+
+This produces a signed `.xpi` file in `dist/firefox-signed/`.
+
+#### Step 3: Install the signed extension
+
+- Drag the `.xpi` file into any Firefox window, **or**
+- Firefox menu → File → Open File → select the `.xpi`
+- Click "Add" when prompted
+
+The signed `.xpi` is **permanent** — it survives browser restarts, updates, everything. No store listing, no review process, no fees.
 
 ### Firefox (temporary, for development)
-```
+```bash
 npm install && npm run run:firefox
 ```
-Opens Firefox with the extension pre-loaded. Reloads on file changes.
-
-No store required for either browser.
+Opens Firefox with the extension pre-loaded. Auto-reloads on file changes. Resets when Firefox closes.
 
 ## Architecture
 
 ```
-manifest.json           — Extension manifest (Manifest V3)
+manifest.json           — Chrome extension manifest (Manifest V3)
+manifest.firefox.json   — Firefox variant (adds gecko ID for signing)
+build.sh                — Copies the right manifest to dist/{chrome,firefox}/
 src/
   background/
     service-worker.js   — Badge management, logging coordination
@@ -59,11 +109,12 @@ src/
     content.js          — Page script (main world) — hooks fetch(), does substitution
     content.css         — Visual indicators (highlights, reveals)
   popup/
-    popup.html/css/js   — Quick access: add mappings, view activity, test mode
+    popup.html/css/js   — Quick access: identity, mappings, activity, test mode
   options/
     options.html/css/js — Full mapping management, import/export, settings
   lib/
-    substitution-engine.js — Core find/replace logic
+    substitution-engine.js — Core explicit find/replace logic
+    smart-patterns.js   — Auto-detection of emails, names, usernames, hostnames, phones, paths
     storage.js          — Browser storage wrapper
     browser-polyfill.js — Chrome/Firefox API compatibility
 ```
@@ -73,3 +124,4 @@ src/
 - All data stays local in browser storage
 - No external servers, no telemetry, no analytics
 - The extension only activates on claude.ai
+- Your real identity data never leaves your machine

src/content/content.js

@@ -186,15 +186,22 @@
       }
     }
 
-    // Usernames + paths
+    // Usernames + hostnames + paths
     if (id.enabled.usernames !== false) {
+      const hostMap = new Map();
+      for (const h of (id.hostnames || [])) {
+        if (h.real && h.substitute) hostMap.set(h.real.toLowerCase(), h);
+      }
+
       for (const u of (id.usernames || [])) {
         if (!u.real || !u.substitute) continue;
 
-        // user@hostname
+        // user@hostname (substitute both username and hostname if configured)
         result = result.replace(new RegExp(esc(u.real) + '@[a-zA-Z0-9._\\-]+', 'g'), (matched) => {
           const host = matched.slice(u.real.length + 1);
-          const sub = u.substitute + '@' + host;
+          const hostEntry = hostMap.get(host.toLowerCase());
+          const subHost = hostEntry ? hostEntry.substitute : host;
+          const sub = u.substitute + '@' + subHost;
           replacements.push({ original: matched, replaced: sub, category: 'username', pattern: 'smart' });
           return sub;
         });
@@ -228,6 +235,16 @@
           });
         }
       }
+
+      // Standalone hostname substitution
+      for (const [, h] of hostMap) {
+        if (h.real.length >= 3) {
+          result = result.replace(new RegExp('\\b' + esc(h.real) + '\\b', 'gi'), (matched) => {
+            replacements.push({ original: matched, replaced: h.substitute, category: 'hostname', pattern: 'smart' });
+            return h.substitute;
+          });
+        }
+      }
     }
 
     return { text: result, replacements };

src/lib/smart-patterns.js

@@ -222,13 +222,17 @@ const SmartPatterns = {
     return { text: result, replacements };
   },
 
-  // ----- Usernames -----
+  // ----- Usernames + Hostnames -----
   // Catches: user@hostname, ~username, /home/username, mentions of username
-  // in shell/code contexts
+  // in shell/code contexts. Also substitutes hostnames independently.
   _substituteUsernames(text, identity) {
     const replacements = [];
     let result = text;
     const usernames = identity.usernames || [];
+    const hostMap = new Map();
+    for (const h of (identity.hostnames || [])) {
+      if (h.real && h.substitute) hostMap.set(h.real.toLowerCase(), h);
+    }
 
     for (const u of usernames) {
       if (!u.real || !u.substitute) continue;
@@ -240,7 +244,10 @@ const SmartPatterns = {
       );
       result = result.replace(userHostRegex, (matched) => {
         const host = matched.slice(u.real.length + 1);
-        const sub = u.substitute + '@' + host;
+        // Also substitute hostname if configured
+        const hostEntry = hostMap.get(host.toLowerCase());
+        const subHost = hostEntry ? hostEntry.substitute : host;
+        const sub = u.substitute + '@' + subHost;
         replacements.push({
           original: matched,
           replaced: sub,
@@ -279,6 +286,22 @@ const SmartPatterns = {
       }
     }
 
+    // Standalone hostname substitution (catches hostnames appearing on their own)
+    for (const [, h] of hostMap) {
+      if (h.real.length >= 3) {
+        const hostRegex = new RegExp('\\b' + esc(h.real) + '\\b', 'gi');
+        result = result.replace(hostRegex, (matched) => {
+          replacements.push({
+            original: matched,
+            replaced: h.substitute,
+            category: 'hostname',
+            pattern: 'smart-hostname',
+          });
+          return h.substitute;
+        });
+      }
+    }
+
     return { text: result, replacements };
   },
 

src/popup/popup.html

@@ -74,7 +74,12 @@
           <span class="arrow">&rarr;</span>
           <input type="text" id="idUserSub" placeholder="ademo" class="input input-sm">
         </div>
-        <div class="id-hint">Catches: jsmith@hostname, /home/jsmith, ~jsmith, C:\Users\jsmith</div>
+        <div class="id-row">
+          <input type="text" id="idHostReal" placeholder="macbook-pro" class="input input-sm">
+          <span class="arrow">&rarr;</span>
+          <input type="text" id="idHostSub" placeholder="mycomputer" class="input input-sm">
+        </div>
+        <div class="id-hint">Catches: jsmith@macbook-pro, /home/jsmith, ~jsmith, C:\Users\jsmith</div>
       </div>
 
       <div class="id-section">

src/popup/popup.js

@@ -111,6 +111,11 @@ function loadIdentityForm() {
     $('#idUserReal').value = user.real || '';
     $('#idUserSub').value = user.substitute || '';
   }
+  const host = (identity.hostnames || [])[0];
+  if (host) {
+    $('#idHostReal').value = host.real || '';
+    $('#idHostSub').value = host.substitute || '';
+  }
   if (phone) {
     $('#idPhoneReal').value = phone.real || '';
     $('#idPhoneSub').value = phone.substitute || '';
@@ -144,6 +149,13 @@ async function saveIdentity() {
     usernames.push({ real: userReal, substitute: userSub });
   }
 
+  const hostnames = [];
+  const hostReal = $('#idHostReal').value.trim();
+  const hostSub = $('#idHostSub').value.trim();
+  if (hostReal && hostSub) {
+    hostnames.push({ real: hostReal, substitute: hostSub });
+  }
+
   const phones = [];
   const phoneReal = $('#idPhoneReal').value.trim();
   const phoneSub = $('#idPhoneSub').value.trim();
@@ -155,6 +167,7 @@ async function saveIdentity() {
     names,
     emails,
     usernames,
+    hostnames,
     phones,
     catchAllEmail: $('#idCatchAllEmail').value.trim(),
     emailDomains: identity.emailDomains || [],