# Lit reference adapter

Projects the technology-neutral IR (`ir/`) onto the Lit stack. This is the
**reference** adapter — the contract every stack adapter implements lives in
[`adapters/ADAPTER_CONTRACT.md`](../ADAPTER_CONTRACT.md).

Run it with **`make adapt-lit`** (`adapters/lit/adapt.mjs`).

## What it does

Per the contract, an adapter is **scaffold + drift-detect**, never a rewrite:

| Concern | Behaviour | Status |
|---|---|---|
| **Tokens** | **Fully generated** from `ir/tokens.json` into the `:root` block of `src/styles/colors_and_type.css`, between `@generated tokens` markers. Deterministic — re-running with an unchanged IR is a byte-identical no-op. The hand-authored type/utility CSS after the block is preserved. | **done (T06)** |
| **New component** | Generate a `<wn-*>` Lit stub from the IR contract's prop→attribute map + a behaviour `TODO`. | T07 |
| **Changed component** | Emit a **drift report** (`adapters/lit/drift/<Name>.md`) — never overwrite the hand-authored element. | T07 |

## Directionality

One-way: **React → `ir/` → Lit**. This adapter is downstream of the IR; it never
writes back to `ir/` or to the React designbook. A change to the shared language is
made in Claude Design and re-propagated (`make designbook-pull && make ir &&
make adapt-lit`). See `.claude/rules/designbook-propagation.md`.

## Token regeneration is a visual change

Because tokens are fully generated, regenerating them can change rendered
appearance when the canonical React designbook has moved (e.g. a font-stack or
colour change). That makes the Playwright baselines diverge **by design** — it is a
human review point, not an error:

```
make adapt-lit          # regenerates tokens
pnpm test:visual        # will fail where appearance changed
# review the change, then if correct:
pnpm test:visual:update # accept new baselines
```

Never run `test:visual:update` to silence a token change without reviewing it — that
defeats the parity gate (T08).

## Exit codes

`0` ok · `2` usage/config · `3` drift detected · `4` parity failure · `5` internal.