# ImposterShield extension (v0.1)

The traffic light. Toolbar icon turns **red** when the page carries a lot of provable AI
content, **yellow** when there is some, **green** when none was found. Flagged images
also get an outline right on the page, and the popup explains every flag in a plain
sentence.

## What it actually detects (honesty contract)

We only flag what we can point to:

1. **Content Credentials / C2PA data inside the image bytes** — `trainedAlgorithmicMedia`
   is the standard stamp for AI output. This is proof, not a guess.
2. **AI tool names in the file's own metadata** (EXIF/XMP): Midjourney, Stable Diffusion,
   DALL-E, Firefly, Ideogram, Leonardo, FLUX, OpenAI.
3. **Images served from AI-only hosts** (oaiusercontent.com, mj-gallery.com,
   replicate.delivery, etc.).
4. **Pages that declare an AI generator** in their meta tags.

A C2PA signature *without* AI markers is treated as a good sign (creator-signed content)
and the popup says so. Green = "no markers found," never "guaranteed real" — the popup
fine print says this out loud.

What it deliberately does NOT do: guess whether text "sounds like AI," or claim to detect
AI images that were stripped of metadata. No overpromising.

## Verdict thresholds

- **Red**: 3+ flagged images, or half or more of what was checked (min 2).
- **Yellow**: 1-2 flagged, or the page declares an AI generator.
- **Green**: nothing found.
- **Gray**: still checking, or the page can't be scanned (chrome://, web store).

Checks the 12 largest images (min 100x100), 4 at a time, 6s timeout, 10MB cap per file.

## Load it in Chrome

1. `chrome://extensions`
2. Toggle **Developer mode** (top right)
3. **Load unpacked** → pick this folder (`Projects\impostershield\extension`)
4. Pin it via the puzzle-piece icon so the light is always visible

## Good test pages

- An article full of Midjourney/DALL-E images (many AI news posts) → should go yellow/red
- A plain news site with staff photography → should stay green
- Adobe Firefly's community gallery → red

## Known limits (v0.1)

- Most social platforms (Instagram, X, Facebook) strip image metadata on upload, so AI
  images there mostly won't carry markers. Host-based detection still works.
- Some CDNs block cross-origin fetches; those images count as "unreadable," not flagged.
- Icon light is per-tab and resets on every navigation.
