feat: initial Silent Send browser extension

Chrome Manifest V3 extension that intercepts personal data and substitutes it with user-defined replacements before sending to Claude.ai. Hooks fetch() in the page's main world to catch API requests, with bidirectional substitution (real→fake on send, fake→real on display via reveal mode). Includes popup UI with mapping management, live test/diff view, activity log with badge count, options page with import/export, and Shadow DOM traversal for Claude.ai compatibility. https://claude.ai/code/session_01Dvgwe7XMoSxnWXkih8p1Cw
2026-03-25 23:26:13 +00:00
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+# Silent Send
+
+A Chrome extension 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
+
+## 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
+- **Reveal mode** (eye icon) toggles showing real vs substitute data in responses
+- **Browser DevTools** → Console shows `[Silent Send] Substituted N value(s)` messages
+
+## Installation (Developer Mode)
+
+1. Clone this repo
+2. Open `chrome://extensions/` in Chrome
+3. Enable **Developer mode** (top right)
+4. Click **Load unpacked**
+5. Select this directory
+6. Navigate to claude.ai — the extension is active
+
+No build step needed. No Chrome Web Store required.
+
+## Architecture
+
+```
+manifest.json           — Extension manifest (Manifest V3)
+src/
+  background/
+    service-worker.js   — Badge management, logging coordination
+  content/
+    injector.js         — Content script (isolated world) — loads config, bridges messaging
+    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
+  options/
+    options.html/css/js — Full mapping management, import/export, settings
+  lib/
+    substitution-engine.js — Core find/replace logic
+    storage.js          — Chrome storage wrapper
+```
+
+## Privacy
+
+- All data stays local in Chrome storage
+- No external servers, no telemetry, no analytics
+- The extension only activates on claude.ai