# Vision & principles of the `@ng-eventually/sdk` polyfill

## Purpose

A **stand-in faithful in SHAPE** to NextGraph's future primitives. **Single** objective: that consumers (Festipod) be **coded against the CORRECT mental model** — the one of finished NextGraph — and have **NOTHING to rewrite** when NextGraph provides the real primitives.

## What the polyfill is NOT

A **security** layer. The **shared wallet** (everyone shares the same keys) plus the absence of real crypto make the emulation **infinitely less secure** than a wallet-per-user — it is a **dev/staging vehicle**, not a goal. **Insecurity is ACCEPTED.** An attacker who bypasses the emulation is not our problem.

## The only criterion: shape-fidelity, with RIGOR

The **exposed surfaces** must match the **exact SHAPE** of the future primitives, **even where enforcement is simulated**. The **failure mode to avoid**: exposing the **wrong shape** → the consumer codes against a model that will not exist → rewrite. The **ACL** inversion of ReadCaps was exactly that defect (an ACL where the real thing is **key possession**) — a lack of rigor.

## Simulating crypto to PREVENT shortcuts

Without a minimum of crypto simulation, damaging shortcuts get taken (reading the plaintext, falling back on ACLs). The polyfill therefore **simulates** the final mechanism, enough to hold this **invariant**:

> **A `did` (bare id, WITHOUT a ReadCap) and a NURI (WITH a ReadCap) are treated GENUINELY differently: the former does NOT allow reading the data; the latter is SUFFICIENT and REQUIRED.**

Concretely, **in the target**: a document's data is **stored encrypted** (per-doc symmetric encryption, however lightweight); the **ReadCap = the key**; without it, **decrypting/reading is impossible**. No ACL, no plaintext accessible "on the side". Obtaining read access = **holding the key**, exactly as in the target model.

> **Not yet true here, and saying so matters.** The shape is in place — possession decides, every access is confined to the connected virtual user, caps are stored and read back — but the cap value is the constant `OK` and nothing is encrypted. Per-document encryption is **P1b**, and it is one function (`mintCap`, in `emulated-verifier/caps.ts` — this said `nuri.ts` until 2026-08-10). Until it lands, nothing this library does may be described as anonymous or private.

## Shape consequences (to respect everywhere)

- **Everything is keys and URLs.** There is **no** notion of membership, role, or authorization list in the model: only symmetric and asymmetric cryptography, URIs, and who holds which key. Any exposed shape that looks like an ACL, a `member`, a `role`, or a `permission` is a **wrong shape**, whatever scaffolding one may otherwise read in the current state of NextGraph.
- **Reading = possession of the read key** (ReadCap = `{id, key}`). A bare id (a `did` without a ReadCap) does not read.
- **Writing = possession of the write key** — a key **distinct** from the read key, hence a distinct axis, but **possession too**.
- **Sharing a cap = sealing it to a recipient** (**durable** delivery, at share time — NOT an ACL re-declared every session).
- **Revocation = re-key** (new key; former holders keep the old state). Non-retroactive.
- **Cap-less reference** (naming/pointing without reading) **distinct** from the cap-bearing reference.

See `readcap-and-nuri-model.md` (the real model, verified in `nextgraph-rs`) and `briefs/2026-07-20-caps-emulation-alignment.md` (the alignment effort).