+++
title = "Implement GET /api/ — serve OpenAPI spec as JSON"
priority = 5
status = "todo"
ticket_type = "task"
dependencies = ["1f5bb5", "8892d5"]
+++

<context>
The `quotesdb` API is built with Axum + Tokio, targeting Cloudflare Workers via `workers-rs`. It serves JSON at `/api/*` endpoints and persists data to Cloudflare D1 (production) or a local SQLite file via Turso (development). Source lives in `src/bin/api/`.

Shared types and utilities are in `src/lib.rs` — code placed there must compile for both the host target and `wasm32-unknown-unknown`.

The `GET /api/` endpoint serves the OpenAPI 3.1.0 specification as JSON. This endpoint requires no authentication and is the entry point for API documentation and client generation.
</context>

<goal>
Implement the `GET /api/` handler that returns the OpenAPI spec as `application/json`.

Strategy resolved in TRIAGE 2ec8b1: **compile-time embed via `build.rs`** (ticket 8892d5).
The `build.rs` converts `api/openapi.yaml` to JSON at build time and writes it to
`$OUT_DIR/openapi.json`. The handler serves this as a static `&str`:

```rust
// Embedded at compile time by build.rs — no runtime parsing, no serde_yaml in binary.
const OPENAPI_JSON: &str = include_str!(concat!(env!("OUT_DIR"), "/openapi.json"));

pub async fn get_openapi_spec() -> impl IntoResponse {
    (
        [(axum::http::header::CONTENT_TYPE, "application/json")],
        OPENAPI_JSON,
    )
}
```

Register the route in the Axum router as `GET /api/`.
</goal>

<constraints>
- The response `Content-Type` must be `application/json`.
- Do NOT use `serde_yaml` in this handler — the YAML→JSON conversion is done by `build.rs`
  (ticket 8892d5). The handler only serves a pre-built static string.
- Do NOT use `OnceLock` or lazy parsing — `OPENAPI_JSON` is a `const &str` embedded at
  compile time; no initialisation is needed.
- The spec at `api/openapi.yaml` is the source of truth — validate with
  `redocly lint api/openapi.yaml` after any changes.
</constraints>

<skills>
Use `superpowers:test-driven-development` — write a test that hits `GET /api/` and asserts the response is valid JSON with an `openapi` key.
Use `superpowers:verification-before-completion` before closing.
</skills>

<validation>
Run in order from the `quotesdb/` directory:

```sh
cargo fmt
cargo check
cargo clippy
cargo test
```
</validation>

<commit>
`feat(quotesdb): implement GET /api/ to serve OpenAPI spec as JSON`
</commit>