feat(series): land on the current episode, not season 1 (UR-062, UR-063, UR-064)

Opening a series dumped the viewer at the top of season 1, and its Play
button played nothing at all: it resolved `$libraryItems[0]` — the first
*season* by SortName — and navigated to `/player/<seasonId>`, which the
player route bounced straight back to `/library/<seasonId>`.

The backend could already answer "where is this viewer in this show":
`repository_get_next_up_episodes` has accepted a `series_id` since it was
written and no caller had ever passed one.

Backend (DR-101, DR-106)
- `repository/series_progress.rs`: `pick_current_episode` — in progress,
  else Next Up, else first unwatched, else the premiere. The third rung is
  the offline path, where Next Up is always empty. `sort_series_order` puts
  specials (season 0) after the numbered seasons.
- `repository_get_series_episodes` takes over the season fan-out and the
  flat-series fallback, which were domain knowledge living in the frontend.
- `clear_watch_history` maps to Jellyfin's mark-unplayed (recursive over a
  container, also zeroes resume). Offline it refuses rather than diverging
  state the next sync would undo.

Frontend (DR-102, DR-103, DR-104, DR-107)
- Seasons collapse; only the current one is expanded, and the current
  episode is badged and scrolled into view.
- Hero button reads `Resume S2E4` / `Play S1E1` and opens that episode's
  focus view, where Play commits (ux-flows §5B.5).
- Seasons are no longer a destination: `/library/<seasonId>` redirects to
  `/library/<seriesId>#season-N`, and every inbound link follows.
- The "More Episodes" strip spans the whole series, so a season finale
  offers the next premiere instead of dead-ending (§5B.2).
- Clear-history buttons on the series hero and each season header.

Routes (DR-105)
- `/library/tv` and `/library/movies` absorb their all-titles and genres
  pages as `?view=` tabs; the four legacy routes redirect. 6 video routes
  become 2, and `/library/shows/genres` stops being the odd one out.

Logic extracted to `seriesNavigation.ts`, `episodeStrip.ts` and
`libraryView.ts` so it is unit-tested rather than buried in components.
Spec: docs/specs/series-current-episode-navigation.md

src-tauri/src/repository/hybrid.rs

@@ -750,6 +750,11 @@ impl MediaRepository for HybridRepository {
         self.online.unmark_favorite(item_id).await
     }
 
+    async fn clear_watch_history(&self, item_id: &str) -> Result<(), RepoError> {
+        // Write operations go directly to server
+        self.online.clear_watch_history(item_id).await
+    }
+
     async fn get_person(&self, person_id: &str) -> Result<MediaItem, RepoError> {
         let offline = Arc::clone(&self.offline);
         let online = Arc::clone(&self.online);
@@ -1128,6 +1133,10 @@ mod tests {
             unimplemented!()
         }
 
+        async fn clear_watch_history(&self, _item_id: &str) -> Result<(), RepoError> {
+            unimplemented!()
+        }
+
         async fn get_person(&self, _person_id: &str) -> Result<MediaItem, RepoError> {
             unimplemented!()
         }
@@ -1386,6 +1395,10 @@ mod tests {
             unimplemented!()
         }
 
+        async fn clear_watch_history(&self, _item_id: &str) -> Result<(), RepoError> {
+            unimplemented!()
+        }
+
         async fn get_person(&self, _person_id: &str) -> Result<MediaItem, RepoError> {
             unimplemented!()
         }

src-tauri/src/repository/mod.rs

@@ -1,6 +1,7 @@
 pub mod hybrid;
 pub mod offline;
 pub mod online;
+pub mod series_progress;
 pub mod types;
 
 pub use hybrid::HybridRepository;
@@ -211,6 +212,14 @@ pub trait MediaRepository: Send + Sync {
     /// Unmark item as favorite
     async fn unmark_favorite(&self, item_id: &str) -> Result<(), RepoError>;
 
+    /// Erase the viewer's watch history for an item: clear its played flag and
+    /// its resume position. On a container (series, season) this applies to
+    /// everything inside it, so a series is returned to "never watched" and
+    /// reopens on its premiere.
+    ///
+    /// TRACES: UR-064 | DR-106
+    async fn clear_watch_history(&self, item_id: &str) -> Result<(), RepoError>;
+
     /// Get person details
     async fn get_person(&self, person_id: &str) -> Result<MediaItem, RepoError>;
 

src-tauri/src/repository/offline.rs

@@ -1627,6 +1627,12 @@ impl MediaRepository for OfflineRepository {
         Err(RepoError::Offline)
     }
 
+    async fn clear_watch_history(&self, _item_id: &str) -> Result<(), RepoError> {
+        // Erasing history has to reach the server to be meaningful — clearing
+        // it only locally would be silently undone by the next sync.
+        Err(RepoError::Offline)
+    }
+
     async fn get_person(&self, person_id: &str) -> Result<MediaItem, RepoError> {
         let query = Query::with_params(
             "SELECT id, name, overview, primary_image_tag

src-tauri/src/repository/online.rs

@@ -1691,6 +1691,48 @@ impl MediaRepository for OnlineRepository {
         result
     }
 
+    /// `DELETE /Users/{userId}/PlayedItems/{itemId}` — Jellyfin's "mark
+    /// unplayed", which also zeroes the resume position. On a folder (series,
+    /// season) the server applies it recursively to the children.
+    ///
+    /// TRACES: UR-064 | DR-106, JA-033
+    async fn clear_watch_history(&self, item_id: &str) -> Result<(), RepoError> {
+        let endpoint = format!("/Users/{}/PlayedItems/{}", self.user_id, item_id);
+        let url = format!("{}{}", self.server_url, endpoint);
+
+        let result = async {
+            let request = self
+                .http_client
+                .client
+                .delete(&url)
+                .header("X-Emby-Authorization", self.auth_header())
+                .build()
+                .map_err(|e| RepoError::Network {
+                    message: format!("Failed to build request: {}", e),
+                })?;
+
+            let response = self
+                .http_client
+                .request_with_retry(request)
+                .await
+                .map_err(|e| RepoError::Network {
+                    message: e.to_string(),
+                })?;
+
+            if !response.status().is_success() {
+                return Err(RepoError::Server {
+                    message: format!("HTTP {}", response.status()),
+                });
+            }
+
+            Ok(())
+        }
+        .await;
+
+        self.report_outcome(&result).await;
+        result
+    }
+
     async fn get_person(&self, person_id: &str) -> Result<MediaItem, RepoError> {
         let endpoint = format!("/Users/{}/Items/{}", self.user_id, person_id);
         let item: JellyfinItem = self.get_json(&endpoint).await?;

src-tauri/src/repository/series_progress.rs

@@ -0,0 +1,433 @@
+//! Where a viewer is in a TV series.
+//!
+//! This is domain policy, not presentation: it encodes what Jellyfin's user-data
+//! means ("in progress", "played") and what Jellyfin's season numbering means
+//! (season 0 is specials). The frontend asks for *the* current episode and
+//! renders it; it does not get to decide what "current" means.
+//!
+//! Split into a pure half (`pick_current_episode`, `sort_series_order`) and an
+//! I/O half (`fetch_series_episodes`, `resolve_current_episode`) so the policy
+//! can be unit-tested without standing up a repository.
+//!
+//! TRACES: UR-062 | DR-101
+
+use super::{GetItemsOptions, MediaItem, MediaRepository, RepoError};
+
+/// Jellyfin files specials under season 0.
+const SPECIALS_SEASON: i32 = 0;
+
+/// Below this fraction watched, a position is a false start rather than
+/// progress — the same threshold the resume dialog uses.
+const MIN_PROGRESS_FRACTION: f64 = 0.01;
+
+/// Above this fraction watched, an episode is effectively finished; resuming it
+/// would drop the viewer into the closing credits.
+const MAX_PROGRESS_FRACTION: f64 = 0.95;
+
+/// Sort key for a season number. Specials sort *after* every numbered season:
+/// a viewer works through S1, S2, … and only then the extras, so season 0 must
+/// not lead just because `0 < 1`.
+fn season_rank(season: Option<i32>) -> i64 {
+    match season {
+        Some(SPECIALS_SEASON) => i64::MAX,
+        Some(n) => n as i64,
+        None => i64::MAX - 1,
+    }
+}
+
+/// Order episodes as the series is watched: season ascending, then episode,
+/// specials last.
+pub fn sort_series_order(episodes: &mut [MediaItem]) {
+    episodes.sort_by(|a, b| {
+        season_rank(a.parent_index_number)
+            .cmp(&season_rank(b.parent_index_number))
+            .then(
+                a.index_number
+                    .unwrap_or(0)
+                    .cmp(&b.index_number.unwrap_or(0)),
+            )
+    });
+}
+
+/// Is this episode genuinely part-watched (not a false start, not finished)?
+fn is_in_progress(item: &MediaItem) -> bool {
+    let Some(user_data) = item.user_data.as_ref() else {
+        return false;
+    };
+    if user_data.is_played.unwrap_or(false) {
+        return false;
+    }
+
+    let position_ms = user_data
+        .playback_position_ms
+        .or_else(|| user_data.playback_position_ticks.map(|t| t / 10_000))
+        .unwrap_or(0);
+    if position_ms <= 0 {
+        return false;
+    }
+
+    // Without a duration we cannot tell "2 minutes in" from "2 minutes left",
+    // so any recorded position counts as progress.
+    let Some(duration_ms) = item.duration_ms.filter(|d| *d > 0) else {
+        return true;
+    };
+
+    let fraction = position_ms as f64 / duration_ms as f64;
+    (MIN_PROGRESS_FRACTION..MAX_PROGRESS_FRACTION).contains(&fraction)
+}
+
+fn is_played(item: &MediaItem) -> bool {
+    item.user_data
+        .as_ref()
+        .and_then(|u| u.is_played)
+        .unwrap_or(false)
+}
+
+fn belongs_to_series(item: &MediaItem, series_id: &str) -> bool {
+    item.series_id.as_deref() == Some(series_id)
+}
+
+/// The episode a viewer should land on when they open `series_id`.
+///
+/// Order of preference, and why:
+///
+/// 1. **An episode in progress.** That is literally where playback stopped;
+///    Next Up would skip past it. On a tie the earliest in series order wins, so
+///    a viewer who dipped into a later episode still returns to the one they are
+///    working through.
+/// 2. **The server's Next Up** for this series — it accounts for watch history
+///    we do not cache locally.
+/// 3. **The first unwatched episode** in series order. This is the offline path:
+///    `OfflineRepository::get_next_up_episodes` returns an empty vec, so without
+///    this rung the whole feature would be online-only.
+/// 4. **The first episode**, so a never-watched series opens on its premiere
+///    rather than on nothing.
+///
+/// `next_up` / `resume` entries are honoured even when absent from `episodes`
+/// (the season fan-out can miss an id the server returns), but only when they
+/// belong to this series.
+pub fn pick_current_episode(
+    series_id: &str,
+    episodes: &[MediaItem],
+    next_up: &[MediaItem],
+    resume: &[MediaItem],
+) -> Option<MediaItem> {
+    // 1. In progress — prefer a match inside the ordered episode list so the
+    //    "earliest in series order" tie-break is meaningful; fall back to the
+    //    resume feed for an episode the fan-out missed.
+    if let Some(found) = episodes.iter().find(|e| is_in_progress(e)) {
+        return Some(found.clone());
+    }
+    if let Some(found) = resume
+        .iter()
+        .find(|e| belongs_to_series(e, series_id) && is_in_progress(e))
+    {
+        return Some(found.clone());
+    }
+
+    // 2. Next Up for this series.
+    if let Some(found) = next_up
+        .iter()
+        .find(|e| e.series_id.is_none() || belongs_to_series(e, series_id))
+    {
+        // Prefer the copy from `episodes` when we have one: it carries the
+        // user-data and images the list already fetched.
+        let matched = episodes.iter().find(|e| e.id == found.id);
+        return Some(matched.unwrap_or(found).clone());
+    }
+
+    // 3. First unwatched in series order.
+    if let Some(found) = episodes.iter().find(|e| !is_played(e)) {
+        return Some(found.clone());
+    }
+
+    // 4. First episode — a fully-watched series reopens at the start.
+    episodes.first().cloned()
+}
+
+/// Every episode of a series, in series order.
+///
+/// Jellyfin hangs episodes off season folders, except for "flat" series whose
+/// children are episodes directly. Both shapes are provider vocabulary, so the
+/// fan-out and the fallback live here rather than in the frontend.
+pub async fn fetch_series_episodes(
+    repo: &dyn MediaRepository,
+    series_id: &str,
+) -> Result<Vec<MediaItem>, RepoError> {
+    let children = repo.get_items(series_id, list_options()).await?;
+
+    let mut episodes: Vec<MediaItem> = Vec::new();
+    for season in children.items.iter().filter(|i| is_season(i)) {
+        // One failing season must not blank the whole show.
+        match repo.get_items(&season.id, list_options()).await {
+            Ok(result) => episodes.extend(result.items.into_iter().filter(is_episode)),
+            Err(e) => {
+                log::warn!(
+                    "[series] season {} of {} failed to load: {:?}",
+                    season.id,
+                    series_id,
+                    e
+                );
+            }
+        }
+    }
+
+    // Flat series: the children *are* the episodes.
+    if episodes.is_empty() {
+        episodes.extend(children.items.into_iter().filter(is_episode));
+    }
+
+    sort_series_order(&mut episodes);
+    Ok(episodes)
+}
+
+/// Resolve the current episode, fetching everything the policy needs.
+///
+/// Next Up and resume are best-effort: offline they fail or come back empty, and
+/// `pick_current_episode` has fallbacks for exactly that.
+pub async fn resolve_current_episode(
+    repo: &dyn MediaRepository,
+    series_id: &str,
+) -> Result<Option<MediaItem>, RepoError> {
+    let episodes = fetch_series_episodes(repo, series_id).await?;
+
+    let next_up = repo
+        .get_next_up_episodes(Some(series_id), Some(1))
+        .await
+        .unwrap_or_default();
+    let resume = repo
+        .get_resume_items(Some(series_id), Some(10))
+        .await
+        .unwrap_or_default();
+
+    Ok(pick_current_episode(
+        series_id, &episodes, &next_up, &resume,
+    ))
+}
+
+fn list_options() -> Option<GetItemsOptions> {
+    Some(GetItemsOptions {
+        limit: Some(500),
+        ..Default::default()
+    })
+}
+
+fn is_season(item: &MediaItem) -> bool {
+    item.item_type == "Season" || matches!(item.kind, crate::domain::MediaKind::Season)
+}
+
+fn is_episode(item: &MediaItem) -> bool {
+    item.item_type == "Episode" || matches!(item.kind, crate::domain::MediaKind::Episode)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::repository::UserData;
+
+    const SERIES: &str = "series-1";
+
+    fn episode(id: &str, season: i32, number: i32) -> MediaItem {
+        MediaItem {
+            id: id.to_string(),
+            name: format!("S{season}E{number}"),
+            item_type: "Episode".to_string(),
+            series_id: Some(SERIES.to_string()),
+            parent_index_number: Some(season),
+            index_number: Some(number),
+            duration_ms: Some(1_000_000),
+            ..Default::default()
+        }
+    }
+
+    fn watched(mut item: MediaItem) -> MediaItem {
+        item.user_data = Some(UserData {
+            is_played: Some(true),
+            ..Default::default()
+        });
+        item
+    }
+
+    fn in_progress(mut item: MediaItem, fraction: f64) -> MediaItem {
+        let duration = item.duration_ms.unwrap_or(1_000_000) as f64;
+        item.user_data = Some(UserData {
+            is_played: Some(false),
+            playback_position_ms: Some((duration * fraction) as i64),
+            ..Default::default()
+        });
+        item
+    }
+
+    fn season(n: i32, count: i32) -> Vec<MediaItem> {
+        (1..=count)
+            .map(|i| episode(&format!("s{n}e{i}"), n, i))
+            .collect()
+    }
+
+    #[test]
+    fn sorts_by_season_then_episode() {
+        let mut eps = vec![
+            episode("b", 2, 1),
+            episode("d", 1, 10),
+            episode("a", 1, 2),
+            episode("c", 2, 2),
+        ];
+        sort_series_order(&mut eps);
+        let ids: Vec<&str> = eps.iter().map(|e| e.id.as_str()).collect();
+        assert_eq!(ids, ["a", "d", "b", "c"]);
+    }
+
+    #[test]
+    fn sorts_specials_after_numbered_seasons() {
+        let mut eps = vec![episode("special", 0, 1), episode("premiere", 1, 1)];
+        sort_series_order(&mut eps);
+        let ids: Vec<&str> = eps.iter().map(|e| e.id.as_str()).collect();
+        assert_eq!(ids, ["premiere", "special"]);
+    }
+
+    #[test]
+    fn picks_the_in_progress_episode_over_next_up() {
+        let mut eps = season(1, 5);
+        eps[0] = watched(eps[0].clone());
+        eps[1] = in_progress(eps[1].clone(), 0.4);
+        // The server would send us past it; the half-watched episode wins.
+        let next_up = vec![episode("s1e3", 1, 3)];
+
+        let current = pick_current_episode(SERIES, &eps, &next_up, &[]).unwrap();
+        assert_eq!(current.id, "s1e2");
+    }
+
+    #[test]
+    fn picks_the_earliest_in_progress_episode() {
+        let mut eps = season(1, 5);
+        eps[1] = in_progress(eps[1].clone(), 0.3);
+        eps[3] = in_progress(eps[3].clone(), 0.5);
+
+        let current = pick_current_episode(SERIES, &eps, &[], &[]).unwrap();
+        assert_eq!(current.id, "s1e2");
+    }
+
+    #[test]
+    fn ignores_a_false_start_and_a_finished_episode() {
+        let mut eps = season(1, 5);
+        eps[0] = watched(eps[0].clone());
+        eps[1] = in_progress(eps[1].clone(), 0.001); // barely started
+        eps[2] = in_progress(eps[2].clone(), 0.99); // effectively over
+
+        // Neither counts as progress, so Next Up decides.
+        let next_up = vec![episode("s1e4", 1, 4)];
+        let current = pick_current_episode(SERIES, &eps, &next_up, &[]).unwrap();
+        assert_eq!(current.id, "s1e4");
+    }
+
+    #[test]
+    fn falls_back_to_next_up_when_nothing_is_in_progress() {
+        let eps = season(1, 5);
+        let next_up = vec![episode("s1e3", 1, 3)];
+
+        let current = pick_current_episode(SERIES, &eps, &next_up, &[]).unwrap();
+        assert_eq!(current.id, "s1e3");
+    }
+
+    #[test]
+    fn next_up_from_another_series_is_ignored() {
+        let eps = season(1, 3);
+        let mut foreign = episode("other-show-ep", 1, 1);
+        foreign.series_id = Some("series-2".to_string());
+
+        let current = pick_current_episode(SERIES, &eps, &[foreign], &[]).unwrap();
+        assert_eq!(current.id, "s1e1");
+    }
+
+    /// The offline path: `OfflineRepository::get_next_up_episodes` returns an
+    /// empty vec, so the first unwatched episode has to carry the feature.
+    #[test]
+    fn falls_back_to_first_unwatched_when_next_up_is_empty() {
+        let mut eps = [season(1, 3), season(2, 3)].concat();
+        for ep in eps.iter_mut().take(4) {
+            *ep = watched(ep.clone());
+        }
+
+        let current = pick_current_episode(SERIES, &eps, &[], &[]).unwrap();
+        assert_eq!(current.id, "s2e2");
+    }
+
+    #[test]
+    fn crosses_a_season_boundary_when_a_season_is_finished() {
+        let mut eps = [season(1, 3), season(2, 3)].concat();
+        for ep in eps.iter_mut().take(3) {
+            *ep = watched(ep.clone());
+        }
+
+        let current = pick_current_episode(SERIES, &eps, &[], &[]).unwrap();
+        assert_eq!(current.id, "s2e1");
+    }
+
+    #[test]
+    fn a_never_watched_series_opens_on_its_premiere() {
+        let eps = [season(2, 3), season(1, 3)].concat();
+        let mut ordered = eps.clone();
+        sort_series_order(&mut ordered);
+
+        let current = pick_current_episode(SERIES, &ordered, &[], &[]).unwrap();
+        assert_eq!(current.id, "s1e1");
+    }
+
+    #[test]
+    fn a_fully_watched_series_reopens_at_the_start() {
+        let eps: Vec<MediaItem> = season(1, 3).into_iter().map(watched).collect();
+
+        let current = pick_current_episode(SERIES, &eps, &[], &[]).unwrap();
+        assert_eq!(current.id, "s1e1");
+    }
+
+    #[test]
+    fn honours_a_resume_entry_missing_from_the_episode_list() {
+        // Season fan-out returned nothing usable, but the resume feed knows.
+        let resume = vec![in_progress(episode("s3e7", 3, 7), 0.5)];
+
+        let current = pick_current_episode(SERIES, &[], &[], &resume).unwrap();
+        assert_eq!(current.id, "s3e7");
+    }
+
+    #[test]
+    fn resume_entries_from_other_series_are_ignored() {
+        let mut foreign = in_progress(episode("other", 1, 1), 0.5);
+        foreign.series_id = Some("series-2".to_string());
+
+        assert!(pick_current_episode(SERIES, &[], &[], &[foreign]).is_none());
+    }
+
+    #[test]
+    fn a_series_with_no_episodes_has_no_current_episode() {
+        assert!(pick_current_episode(SERIES, &[], &[], &[]).is_none());
+    }
+
+    #[test]
+    fn an_episode_without_a_duration_still_counts_as_in_progress() {
+        let mut ep = episode("s1e2", 1, 2);
+        ep.duration_ms = None;
+        ep.user_data = Some(UserData {
+            is_played: Some(false),
+            playback_position_ms: Some(120_000),
+            ..Default::default()
+        });
+
+        let current = pick_current_episode(SERIES, &[episode("s1e1", 1, 1), ep], &[], &[]).unwrap();
+        assert_eq!(current.id, "s1e2");
+    }
+
+    #[test]
+    fn legacy_tick_positions_still_register_as_progress() {
+        let mut ep = episode("s1e2", 1, 2);
+        ep.user_data = Some(UserData {
+            is_played: Some(false),
+            // 400_000 ms expressed in Jellyfin ticks, no ms field.
+            playback_position_ticks: Some(400_000 * 10_000),
+            ..Default::default()
+        });
+
+        let current = pick_current_episode(SERIES, &[episode("s1e1", 1, 1), ep], &[], &[]).unwrap();
+        assert_eq!(current.id, "s1e2");
+    }
+}

src-tauri/src/repository/types.rs

@@ -39,7 +39,7 @@ pub struct Library {
 }
 
 /// User-specific data for an item (playback state, favorites, etc.)
-#[derive(specta::Type, Debug, Clone, Serialize, Deserialize)]
+#[derive(specta::Type, Debug, Clone, Serialize, Deserialize, Default)]
 #[serde(rename_all = "camelCase")]
 pub struct UserData {
     /// Legacy Jellyfin resume position in ticks. Being replaced by