feat(api): list roots with policy names

The §9.2 add flow pre-fills root and policy; without this endpoint the
SPA has no way to know either. No issue covers it separately.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.sqlx/query-fa84977e249cb6f3b95d5f3486346450066ac2997437175e30c60d6364701dcf.json

@@ -0,0 +1,50 @@
+{
+  "db_name": "SQLite",
+  "query": "SELECT r.id AS \"id!: i64\", r.kind AS \"kind!: String\", r.audience AS \"audience!: String\", r.path AS \"path!: String\", p.id AS \"policy_id!: i64\", p.name AS \"policy_name!: String\" FROM roots r JOIN policies p ON p.id = r.policy_id ORDER BY r.id",
+  "describe": {
+    "columns": [
+      {
+        "name": "id!: i64",
+        "ordinal": 0,
+        "type_info": "Integer"
+      },
+      {
+        "name": "kind!: String",
+        "ordinal": 1,
+        "type_info": "Text"
+      },
+      {
+        "name": "audience!: String",
+        "ordinal": 2,
+        "type_info": "Text"
+      },
+      {
+        "name": "path!: String",
+        "ordinal": 3,
+        "type_info": "Text"
+      },
+      {
+        "name": "policy_id!: i64",
+        "ordinal": 4,
+        "type_info": "Integer"
+      },
+      {
+        "name": "policy_name!: String",
+        "ordinal": 5,
+        "type_info": "Text"
+      }
+    ],
+    "parameters": {
+      "Right": 0
+    },
+    "nullable": [
+      false,
+      false,
+      false,
+      false,
+      false,
+      false
+    ]
+  },
+  "hash": "fa84977e249cb6f3b95d5f3486346450066ac2997437175e30c60d6364701dcf"
+}

crates/arr-api/src/lib.rs

@@ -8,6 +8,7 @@
 
 mod health;
 mod movies;
+mod roots;
 mod search;
 mod state;
 
@@ -20,6 +21,7 @@ use utoipa_scalar::{Scalar, Servable};
 
 pub use health::{Check, Health, HealthReport, Status};
 pub use movies::{Accepted, AttentionQueues, CreateMovie, ErrorBody, Movie, Release, UpdateMovie};
+pub use roots::Root;
 pub use search::{ClassifiedRelease, SearchResponse};
 pub use state::{AppState, MovieCommand, Upstreams, DEFAULT_TMDB_URL};
 
@@ -42,7 +44,8 @@ pub const DOCS_PATH: &str = "/api/docs";
     tags(
         (name = "system", description = "Service health and metadata"),
         (name = "movies", description = "Movie library and actions"),
-        (name = "search", description = "Unified title and release search")
+        (name = "search", description = "Unified title and release search"),
+        (name = "roots", description = "Root folders and their policies")
     ),
 )]
 struct ApiDoc;
@@ -59,6 +62,7 @@ fn api_router() -> OpenApiRouter<AppState> {
         .routes(routes!(movies::attention))
         .routes(routes!(search::search))
         .routes(routes!(search::releases))
+        .routes(routes!(roots::list))
 }
 
 /// The generated `OpenAPI` document.

crates/arr-api/src/roots.rs

@@ -0,0 +1,79 @@
+use axum::extract::State;
+use axum::Json;
+use serde::Serialize;
+use utoipa::ToSchema;
+
+use crate::movies::{ApiError, ErrorBody};
+use crate::state::AppState;
+
+/// A root folder joined with its policy, enough for the add flow to pre-fill
+/// root and policy (DESIGN.md §9.2) without a second request.
+#[derive(Debug, Clone, Serialize, ToSchema)]
+pub struct Root {
+    pub id: i64,
+    pub kind: String,
+    pub audience: String,
+    pub path: String,
+    pub policy_id: i64,
+    pub policy_name: String,
+}
+
+#[utoipa::path(
+    get, path = "/api/roots", tag = "roots",
+    responses(
+        (status = 200, body = [Root]),
+        (status = 500, body = ErrorBody),
+        (status = 503, body = ErrorBody)
+    )
+)]
+pub async fn list(State(state): State<AppState>) -> Result<Json<Vec<Root>>, ApiError> {
+    let database = state.database().ok_or(ApiError::Unavailable)?;
+    let roots = sqlx::query_as!(
+        Root,
+        r#"SELECT r.id AS "id!: i64", r.kind AS "kind!: String", r.audience AS "audience!: String", r.path AS "path!: String", p.id AS "policy_id!: i64", p.name AS "policy_name!: String" FROM roots r JOIN policies p ON p.id = r.policy_id ORDER BY r.id"#
+    )
+    .fetch_all(database.pool())
+    .await?;
+    Ok(Json(roots))
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::state::Upstreams;
+    use crate::{router, AppState};
+
+    #[tokio::test]
+    async fn roots_carry_their_policy_name() {
+        let dir = tempfile::tempdir().expect("tempdir");
+        let database = arr_db::Db::connect(dir.path().join("arr.db"))
+            .await
+            .expect("database");
+        database.migrate().await.expect("migrate");
+        let state = AppState::new(Upstreams::new(
+            "http://127.0.0.1:1".into(),
+            "http://127.0.0.1:1".into(),
+        ))
+        .expect("state")
+        .with_database(database);
+        let listener = tokio::net::TcpListener::bind("127.0.0.1:0")
+            .await
+            .expect("bind");
+        let address = listener.local_addr().expect("address");
+        let app = router(state);
+        tokio::spawn(async move { axum::serve(listener, app).await.expect("serve") });
+
+        let roots: Vec<serde_json::Value> = reqwest::get(format!("http://{address}/api/roots"))
+            .await
+            .expect("roots")
+            .json()
+            .await
+            .expect("json");
+        assert_eq!(roots.len(), 2, "the two seeded movie roots: {roots:?}");
+        assert_eq!(roots[0]["audience"], "main");
+        assert_eq!(roots[0]["policy_name"], "Movies — main");
+        assert_eq!(roots[1]["audience"], "kids");
+        assert!(roots[1]["path"]
+            .as_str()
+            .is_some_and(|p| p.contains("kids")));
+    }
+}