feat(mangas): per-field sort options + direction toggle on the catalog (0.88.0)

Replace the two-option `ListSort` enum with an orthogonal sort field
(created/updated/title/author, default updated) and direction
(asc/desc, default desc). The catalog now defaults to last-updated-first
and lets the user order by any field in either direction.

Backend builds ORDER BY from the enums only (no injection seam), with a
NULLS-LAST author subquery and a stable id tie-break. Frontend adds a
direction toggle with per-field defaults (dates desc, text asc) and
labels (Newest/Oldest vs A->Z/Z->A), reusing SegmentedControl; URL state
omits the per-field defaults and validates on hydrate.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/tests/api_mangas.rs

@@ -11,6 +11,53 @@ fn metadata(title: &str) -> serde_json::Value {
     json!({ "title": title })
 }
 
+/// Collect the `title` field of every item in a list response, in order.
+fn title_list(body: &serde_json::Value) -> Vec<&str> {
+    body["items"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|m| m["title"].as_str().unwrap())
+        .collect()
+}
+
+/// Create a manga via the upload API, asserting it succeeded.
+async fn seed(app: &axum::Router, cookie: &str, title: &str) {
+    let resp = app
+        .clone()
+        .oneshot(common::post_multipart_with_cookie(
+            "/api/v1/mangas",
+            MultipartBuilder::new().add_json("metadata", json!({ "title": title })),
+            cookie,
+        ))
+        .await
+        .unwrap();
+    assert_eq!(resp.status(), StatusCode::CREATED, "seed({title}) failed");
+}
+
+/// Pin a manga's `created_at` to an explicit RFC3339 instant so time-based
+/// ordering assertions don't depend on insert timing.
+async fn set_created_at(pool: &PgPool, title: &str, when: &str) {
+    let ts: chrono::DateTime<chrono::Utc> = when.parse().unwrap();
+    sqlx::query("UPDATE mangas SET created_at = $1 WHERE title = $2")
+        .bind(ts)
+        .bind(title)
+        .execute(pool)
+        .await
+        .unwrap();
+}
+
+/// Pin a manga's `updated_at` to an explicit RFC3339 instant.
+async fn set_updated_at(pool: &PgPool, title: &str, when: &str) {
+    let ts: chrono::DateTime<chrono::Utc> = when.parse().unwrap();
+    sqlx::query("UPDATE mangas SET updated_at = $1 WHERE title = $2")
+        .bind(ts)
+        .bind(title)
+        .execute(pool)
+        .await
+        .unwrap();
+}
+
 #[sqlx::test(migrations = "./migrations")]
 async fn list_is_empty_initially(pool: PgPool) {
     let h = common::harness(pool);
@@ -103,21 +150,137 @@ async fn list_sort_title_orders_alphabetically(pool: PgPool) {
             .unwrap();
     }
 
+    // Title sort now requires an explicit direction; the wire default is
+    // `desc`, so A→Z needs `order=asc`.
     let resp = h
         .app
-        .oneshot(common::get("/api/v1/mangas?sort=title"))
+        .oneshot(common::get("/api/v1/mangas?sort=title&order=asc"))
         .await
         .unwrap();
     let body = common::body_json(resp).await;
-    let titles: Vec<&str> = body["items"]
-        .as_array()
-        .unwrap()
-        .iter()
-        .map(|m| m["title"].as_str().unwrap())
-        .collect();
+    let titles = title_list(&body);
     assert_eq!(titles, vec!["Berserk", "One Piece", "Vinland Saga"]);
 }
 
+#[sqlx::test(migrations = "./migrations")]
+async fn list_sort_title_desc_orders_reverse_alphabetically(pool: PgPool) {
+    let h = common::harness(pool);
+    let (_, cookie) = common::register_user(&h.app).await;
+
+    for title in ["Vinland Saga", "Berserk", "One Piece"] {
+        seed(&h.app, &cookie, title).await;
+    }
+
+    let resp = h
+        .app
+        .oneshot(common::get("/api/v1/mangas?sort=title&order=desc"))
+        .await
+        .unwrap();
+    let body = common::body_json(resp).await;
+    let titles = title_list(&body);
+    assert_eq!(titles, vec!["Vinland Saga", "One Piece", "Berserk"]);
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn list_default_sort_is_updated_desc(pool: PgPool) {
+    let h = common::harness(pool.clone());
+    let (_, cookie) = common::register_user(&h.app).await;
+
+    for title in ["Alpha", "Bravo", "Charlie"] {
+        seed(&h.app, &cookie, title).await;
+    }
+    // Pin explicit, distinct update times so the default ordering is
+    // deterministic regardless of insert timing. Bravo is the most recently
+    // updated and must appear first under the default (updated DESC).
+    set_updated_at(&pool, "Alpha", "2020-01-01T00:00:00Z").await;
+    set_updated_at(&pool, "Bravo", "2023-01-01T00:00:00Z").await;
+    set_updated_at(&pool, "Charlie", "2021-01-01T00:00:00Z").await;
+
+    // No sort/order params — exercises the default.
+    let resp = h.app.oneshot(common::get("/api/v1/mangas")).await.unwrap();
+    let body = common::body_json(resp).await;
+    let titles = title_list(&body);
+    assert_eq!(titles, vec!["Bravo", "Charlie", "Alpha"]);
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn list_sort_created_orders_by_creation_time(pool: PgPool) {
+    let h = common::harness(pool.clone());
+    let (_, cookie) = common::register_user(&h.app).await;
+
+    for title in ["Alpha", "Bravo", "Charlie"] {
+        seed(&h.app, &cookie, title).await;
+    }
+    set_created_at(&pool, "Alpha", "2020-01-01T00:00:00Z").await;
+    set_created_at(&pool, "Bravo", "2023-01-01T00:00:00Z").await;
+    set_created_at(&pool, "Charlie", "2021-01-01T00:00:00Z").await;
+
+    // Newest-created first.
+    let resp = h
+        .app
+        .clone()
+        .oneshot(common::get("/api/v1/mangas?sort=created&order=desc"))
+        .await
+        .unwrap();
+    let body = common::body_json(resp).await;
+    assert_eq!(title_list(&body), vec!["Bravo", "Charlie", "Alpha"]);
+
+    // Ascending is the exact reverse.
+    let resp = h
+        .app
+        .oneshot(common::get("/api/v1/mangas?sort=created&order=asc"))
+        .await
+        .unwrap();
+    let body = common::body_json(resp).await;
+    assert_eq!(title_list(&body), vec!["Alpha", "Charlie", "Bravo"]);
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn list_sort_author_orders_by_author_name_nulls_last(pool: PgPool) {
+    let h = common::harness(pool);
+    let (_, cookie) = common::register_user(&h.app).await;
+
+    // Author order is deliberately scrambled relative to title order so the
+    // assertion can't pass by accidentally sorting on title.
+    for (title, authors) in [
+        ("Akira", json!(["Beta Author"])),
+        ("Boku", json!(["Alpha Author"])),
+        ("Chi", json!(["Gamma Author"])),
+        ("NoAuthor", json!([])),
+    ] {
+        let _ = h
+            .app
+            .clone()
+            .oneshot(common::post_multipart_with_cookie(
+                "/api/v1/mangas",
+                MultipartBuilder::new()
+                    .add_json("metadata", json!({ "title": title, "authors": authors })),
+                &cookie,
+            ))
+            .await
+            .unwrap();
+    }
+
+    // Ascending by author name; the authorless manga sorts last (NULLS LAST).
+    let resp = h
+        .app
+        .clone()
+        .oneshot(common::get("/api/v1/mangas?sort=author&order=asc"))
+        .await
+        .unwrap();
+    let body = common::body_json(resp).await;
+    assert_eq!(title_list(&body), vec!["Boku", "Akira", "Chi", "NoAuthor"]);
+
+    // Descending flips the authored mangas but keeps the authorless one last.
+    let resp = h
+        .app
+        .oneshot(common::get("/api/v1/mangas?sort=author&order=desc"))
+        .await
+        .unwrap();
+    let body = common::body_json(resp).await;
+    assert_eq!(title_list(&body), vec!["Chi", "Akira", "Boku", "NoAuthor"]);
+}
+
 #[sqlx::test(migrations = "./migrations")]
 async fn search_reflects_filtered_total(pool: PgPool) {
     let h = common::harness(pool);