SELVAGE

Don’t take our word for it. Read the code that makes the decision.

The demo runs the Selvage enforcement kernel directly in your browser. There is no server round-trip for the allow/block decision — which means you can inspect it, set a breakpoint in it, and try to break it. Here’s how to check it for yourself, in about ten minutes.

The claim, stated precisely

The setup

You approve a cart at checkout — specific items, specific quantities, one total. That approved, priced cart is frozen as the contract. Every submitted transaction is bound to it across three dimensions — item set · per-item quantity · total. Any deviation on any dimension is classified committed_terms_differ_from_approved and blocked before the provider commit.

Verify it — each step stands alone

1. Confirm no server is involved.~30s

   Open DevTools → Network. Run any attack. You’ll see zero requests to a Selvage backend — the only traffic is web fonts. The decision is computed locally, in code you can read.

2. Read the actual decision logic.~2 min

   DevTools → Sources. Search the page bundle for bindPreCommit and compareTerms. The block is a structured comparison of the submitted transaction against the approved terms — not a keyword match on the injection text. Look for anywhere the kernel reads the injection string: you won’t find it, because it doesn’t.

3. Breakpoint it.~2 min

   Set a breakpoint in bindPreCommit. Submit an attack. Inspect the two term sets — approved vs. submitted. Watch the mismatch on item_set / lines / total produce the block. There is no branch keyed on the words “injection” or “attack.”

4. Break it yourself.open-ended

   In Break it yourself, submit any transaction you like — add items, inflate quantities, override the total — and paste any injection text you can invent. Confirm two things:

   • Only the exact approved cart executes. Everything else is blocked.
   • The injection text box changes nothing. The boundary never reads it. That’s the whole point: enforcement is on the transaction, not the prose.
5. Prove the boundary is what’s stopping it.~30s

   Toggle Selvage OFF and submit the same altered transaction. It now reaches the provider (the commit counter increments). Toggle ON, submit again — blocked. The only variable is Selvage. This is the control that separates “the boundary blocked it” from “nothing was going to happen anyway.”

6. Reproducibility.any time

   Re-run any case. Same inputs → same decision, every time. The enforcement is deterministic, not probabilistic.

What this does — and doesn’t — establish