feat(#489): show the last V-code / L-code in use on Admin → Health, with the next free number

docs/manual/en/02-configuration.tex

@@ -13,7 +13,11 @@ \chapter{Configuration}
 configuration file. The panel has six tabs:
 
 \begin{itemize}
-  \item \textbf{Health} — read-only status dashboard.
+  \item \textbf{Health} — read-only status dashboard. Besides versions,
+        entity counts and provider status, it shows the last volume
+        number (V-code) and last shelf number (L-code) ever printed,
+        trashed items included, each with the next free number — the
+        place to look before printing a new sheet of barcode labels.
   \item \textbf{Users} — create / deactivate users, change roles.
   \item \textbf{Reference data} — the taxonomy tables, and the
         management-label vocabulary (section~\ref{sec:management-labels}).

docs/manual/fr/02-configuration.tex

@@ -14,7 +14,12 @@ \chapter{Configuration}
 configuration séparé. Le panneau a six onglets :
 
 \begin{itemize}
-  \item \textbf{Health} — tableau de bord en lecture seule.
+  \item \textbf{Health} — tableau de bord en lecture seule. Outre les
+        versions, les compteurs d'entités et l'état des fournisseurs,
+        il affiche le dernier numéro de volume (code V) et le dernier
+        numéro d'étagère (code L) jamais imprimés, corbeille comprise,
+        chacun avec le prochain numéro libre — à consulter avant
+        d'imprimer une nouvelle planche d'étiquettes.
   \item \textbf{Users} — créer/désactiver des utilisateurs, changer
         de rôle.
   \item \textbf{Reference data} — les tables taxonomiques, et le

locales/de.yml

@@ -852,6 +852,13 @@ admin:
     count_contributors: Mitwirkende
     count_borrowers: Entleiher
     count_active_loans: Aktive Ausleihen
+    labels_heading: Barcode-Etiketten
+    labels_hint: "Höchste je gedruckte Nummer pro Etikettenfamilie, Papierkorb eingeschlossen, und die nächste freie Nummer für einen neuen Etikettenbogen."
+    last_vcode: "Letzte Bandnummer (V-Code)"
+    last_lcode: "Letzte Regalnummer (L-Code)"
+    label_with_next: "%{highest} (nächste: %{next})"
+    label_exhausted: "%{highest} (keine mehr frei)"
+    label_none_yet: "Noch keine"
     providers_heading: Metadaten-Anbieter
     provider_status_up: Erreichbar
     provider_status_down: Nicht erreichbar

locales/en.yml

@@ -867,6 +867,13 @@ admin:
     count_contributors: Contributors
     count_borrowers: Borrowers
     count_active_loans: Active loans
+    labels_heading: Barcode labels
+    labels_hint: "Highest number ever printed for each label family, trashed items included, and the next free number to start a new label sheet from."
+    last_vcode: "Last volume number (V-code)"
+    last_lcode: "Last shelf number (L-code)"
+    label_with_next: "%{highest} (next: %{next})"
+    label_exhausted: "%{highest} (none left)"
+    label_none_yet: "None yet"
     providers_heading: Metadata providers
     provider_status_up: Reachable
     provider_status_down: Unreachable

locales/fr.yml

@@ -864,6 +864,13 @@ admin:
     count_contributors: Contributeurs
     count_borrowers: Emprunteurs
     count_active_loans: "Prêts actifs"
+    labels_heading: "Étiquettes à code-barres"
+    labels_hint: "Numéro le plus élevé jamais imprimé pour chaque famille d'étiquettes, corbeille comprise, et prochain numéro libre pour démarrer une nouvelle planche."
+    last_vcode: "Dernier numéro de volume (code V)"
+    last_lcode: "Dernier numéro d'étagère (code L)"
+    label_with_next: "%{highest} (prochain : %{next})"
+    label_exhausted: "%{highest} (plus aucun disponible)"
+    label_none_yet: "Aucun pour l'instant"
     providers_heading: "Fournisseurs de métadonnées"
     provider_status_up: Accessible
     provider_status_down: Inaccessible

locales/it.yml

@@ -840,6 +840,13 @@ admin:
     count_contributors: Collaboratori
     count_borrowers: Lettori
     count_active_loans: Prestiti attivi
+    labels_heading: Etichette con codice a barre
+    labels_hint: "Numero più alto mai stampato per ogni famiglia di etichette, cestino incluso, e prossimo numero libero da cui iniziare un nuovo foglio."
+    last_vcode: "Ultimo numero di volume (codice V)"
+    last_lcode: "Ultimo numero di scaffale (codice L)"
+    label_with_next: "%{highest} (prossimo: %{next})"
+    label_exhausted: "%{highest} (nessuno disponibile)"
+    label_none_yet: "Nessuno per ora"
     providers_heading: Fornitori di metadati
     provider_status_up: Raggiungibile
     provider_status_down: Non raggiungibile

src/routes/admin.rs

@@ -149,6 +149,15 @@ struct AdminHealthPanel {
     count_borrowers: i64,
     count_active_loans_label: String,
     count_active_loans: i64,
+    // #489 — label high-water marks: "V0142 (next: V0143)" per family,
+    // or the "none yet" placeholder. Pre-formatted so the template only
+    // prints two strings.
+    labels_heading: String,
+    labels_hint: String,
+    last_vcode_label: String,
+    last_vcode_value: String,
+    last_lcode_label: String,
+    last_lcode_value: String,
     providers_heading: String,
     providers: Vec<ProviderHealthRow>,
     // Fix #214: maintenance section — "Re-fetch missing covers".
@@ -1392,6 +1401,11 @@ async fn render_health_panel(state: &AppState, loc: &'static str) -> Result<Stri
 
     let providers = build_provider_rows(&state.registry, &state.provider_health, loc);
 
+    // #489 — label high-water marks (two MAX() lookups, no cache needed).
+    let watermarks = admin_health::label_watermarks(pool).await?;
+    let last_vcode_value = format_label_watermark(watermarks.highest_vcode.as_deref(), loc);
+    let last_lcode_value = format_label_watermark(watermarks.highest_lcode.as_deref(), loc);
+
     // Fix #214: maintenance section data — count of titles with no
     // cover + bulk-fetch status. Cheap query (single SELECT COUNT) and
     // a lock-only status read; no extra DB round-trip beyond the count.
@@ -1451,6 +1465,12 @@ async fn render_health_panel(state: &AppState, loc: &'static str) -> Result<Stri
         count_active_loans_label: rust_i18n::t!("admin.health.count_active_loans", locale = loc)
             .to_string(),
         count_active_loans: counts.active_loans,
+        labels_heading: rust_i18n::t!("admin.health.labels_heading", locale = loc).to_string(),
+        labels_hint: rust_i18n::t!("admin.health.labels_hint", locale = loc).to_string(),
+        last_vcode_label: rust_i18n::t!("admin.health.last_vcode", locale = loc).to_string(),
+        last_vcode_value,
+        last_lcode_label: rust_i18n::t!("admin.health.last_lcode", locale = loc).to_string(),
+        last_lcode_value,
         providers_heading: rust_i18n::t!("admin.health.providers_heading", locale = loc)
             .to_string(),
         providers,
@@ -1491,6 +1511,26 @@ async fn render_health_panel(state: &AppState, loc: &'static str) -> Result<Stri
         .map_err(|_| AppError::Internal("admin health panel render failed".to_string()))
 }
 
+/// #489 — render one label watermark for the Health tab: `V0142 (next: V0143)`,
+/// `V9999 (none left)` when the numeric space is exhausted, or the
+/// "none yet" placeholder when the catalog holds no label of that family.
+fn format_label_watermark(highest: Option<&str>, loc: &str) -> String {
+    match highest {
+        None => rust_i18n::t!("admin.health.label_none_yet", locale = loc).to_string(),
+        Some(h) => match admin_health::next_label(h) {
+            Some(next) => rust_i18n::t!(
+                "admin.health.label_with_next",
+                locale = loc,
+                highest = h,
+                next = next
+            )
+            .to_string(),
+            None => rust_i18n::t!("admin.health.label_exhausted", locale = loc, highest = h)
+                .to_string(),
+        },
+    }
+}
+
 fn build_provider_rows(
     registry: &Arc<ProviderRegistry>,
     map: &ProviderHealthMap,

src/services/admin_health.rs

@@ -76,6 +76,46 @@ pub async fn trash_count(pool: &DbPool) -> Result<i64, AppError> {
     Ok(total)
 }
 
+/// #489 — the label high-water marks shown on the Health tab: the highest
+/// V-code / L-code ever printed and the next free number after each.
+/// `None` for a code family means the catalog holds no label of that
+/// family yet.
+#[derive(Debug, Clone, Default, PartialEq, Eq)]
+pub struct LabelWatermarks {
+    pub highest_vcode: Option<String>,
+    pub highest_lcode: Option<String>,
+}
+
+/// Highest V-code / L-code across the whole catalog, soft-deleted rows
+/// INCLUDED — a printed sticker outlives the row's trash state, so its
+/// number must never be reissued. Delegates to the same two model lookups
+/// that feed the `/catalog` info line (#428) so both surfaces always agree.
+pub async fn label_watermarks(pool: &DbPool) -> Result<LabelWatermarks, AppError> {
+    let highest_vcode = crate::models::volume::VolumeModel::highest_label_any(pool).await?;
+    let highest_lcode = crate::models::location::LocationModel::highest_label_any(pool).await?;
+    Ok(LabelWatermarks {
+        highest_vcode,
+        highest_lcode,
+    })
+}
+
+/// The label that follows `highest` in the fixed-width `X9999` scheme
+/// (`V0142` → `V0143`). Returns `None` when the numeric space is exhausted
+/// (`V9999`) or when the input is not a prefix + exactly four digits — the
+/// caller renders a "none left" placeholder either way rather than
+/// inventing a five-digit code the scanner path would reject.
+pub fn next_label(highest: &str) -> Option<String> {
+    let (prefix, digits) = highest.split_at(highest.len().checked_sub(4)?);
+    if prefix.len() != 1 || !digits.bytes().all(|b| b.is_ascii_digit()) {
+        return None;
+    }
+    let n: u32 = digits.parse().ok()?;
+    if n >= 9999 {
+        return None;
+    }
+    Some(format!("{prefix}{:04}", n + 1))
+}
+
 /// Cached MariaDB `VERSION()` string. The version never changes at runtime;
 /// the 60-second cache amortizes the round-trip across back-to-back Health
 /// loads without making the handler dependent on a DB read for correctness.
@@ -197,6 +237,70 @@ mod tests {
         assert!(used <= total);
     }
 
+    // ─── #489 label watermarks ───────────────────────────────────
+
+    #[test]
+    fn next_label_increments_within_the_fixed_width() {
+        assert_eq!(next_label("V0142").as_deref(), Some("V0143"));
+        assert_eq!(next_label("L0037").as_deref(), Some("L0038"));
+        assert_eq!(next_label("V0009").as_deref(), Some("V0010"));
+        assert_eq!(next_label("V0999").as_deref(), Some("V1000"));
+        assert_eq!(next_label("V0000").as_deref(), Some("V0001"));
+    }
+
+    #[test]
+    fn next_label_is_none_when_the_space_is_exhausted() {
+        assert_eq!(next_label("V9999"), None);
+        assert_eq!(next_label("L9999"), None);
+    }
+
+    #[test]
+    fn next_label_rejects_malformed_input() {
+        assert_eq!(next_label(""), None);
+        assert_eq!(next_label("V"), None);
+        assert_eq!(next_label("V12"), None);
+        assert_eq!(next_label("V00001"), None, "five digits is not a label");
+        assert_eq!(next_label("V00a1"), None);
+        assert_eq!(next_label("0142"), None, "no prefix");
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn label_watermarks_empty_catalog_is_all_none(pool: DbPool) {
+        let w = label_watermarks(&pool).await.unwrap();
+        assert_eq!(w, LabelWatermarks::default());
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn label_watermarks_report_highest_including_soft_deleted(pool: DbPool) {
+        let title_id: u64 = sqlx::query(
+            "INSERT INTO titles (title, media_type, genre_id) VALUES ('T489', 'book', 1)",
+        )
+        .execute(&pool)
+        .await
+        .unwrap()
+        .last_insert_id();
+        sqlx::query(
+            "INSERT INTO volumes (title_id, label, deleted_at) VALUES \
+             (?, 'V0007', NULL), (?, 'V0042', NOW())",
+        )
+        .bind(title_id)
+        .bind(title_id)
+        .execute(&pool)
+        .await
+        .unwrap();
+        sqlx::query(
+            "INSERT INTO storage_locations (name, node_type, label, deleted_at) VALUES \
+             ('Shelf A', 'shelf', 'L0003', NULL), ('Shelf B', 'shelf', 'L0011', NOW())",
+        )
+        .execute(&pool)
+        .await
+        .unwrap();
+
+        let w = label_watermarks(&pool).await.unwrap();
+        assert_eq!(w.highest_vcode.as_deref(), Some("V0042"), "trashed V-code still counts");
+        assert_eq!(w.highest_lcode.as_deref(), Some("L0011"), "trashed L-code still counts");
+    }
+
     // ─── DB-backed tests ─────────────────────────────────────────
 
     #[sqlx::test(migrations = "./migrations")]

templates/fragments/admin_health_panel.html

@@ -28,6 +28,18 @@ <h2 class="text-lg font-semibold text-stone-900 dark:text-stone-100 mb-4">{{ cou
         </tbody>
     </table>
 
+    {# #489 — label high-water marks: highest V-code / L-code ever printed
+       (soft-deleted rows included) and the next free number, so a fresh
+       label sheet starts right after the occupied range. #}
+    <h2 class="text-lg font-semibold text-stone-900 dark:text-stone-100 mb-2">{{ labels_heading }}</h2>
+    <p class="text-sm text-stone-500 dark:text-stone-400 mb-4">{{ labels_hint }}</p>
+    <table class="min-w-full divide-y divide-stone-200 dark:divide-stone-700 mb-8">
+        <tbody class="divide-y divide-stone-100 dark:divide-stone-800">
+            <tr><th scope="row" class="px-3 py-2 text-left text-sm text-stone-500 dark:text-stone-400 font-normal">{{ last_vcode_label }}</th><td id="health-last-vcode" class="px-3 py-2 text-right text-sm font-mono text-stone-900 dark:text-stone-100">{{ last_vcode_value }}</td></tr>
+            <tr><th scope="row" class="px-3 py-2 text-left text-sm text-stone-500 dark:text-stone-400 font-normal">{{ last_lcode_label }}</th><td id="health-last-lcode" class="px-3 py-2 text-right text-sm font-mono text-stone-900 dark:text-stone-100">{{ last_lcode_value }}</td></tr>
+        </tbody>
+    </table>
+
     <h2 class="text-lg font-semibold text-stone-900 dark:text-stone-100 mb-4">{{ providers_heading }}</h2>
     <table class="min-w-full divide-y divide-stone-200 dark:divide-stone-700 mb-8">
         <tbody class="divide-y divide-stone-100 dark:divide-stone-800">