diff --git a/crates/arr-core/src/lib.rs b/crates/arr-core/src/lib.rs
index 11f2517..09de6ef 100644
--- a/crates/arr-core/src/lib.rs
+++ b/crates/arr-core/src/lib.rs
@@ -7,10 +7,12 @@ use std::{collections::BTreeMap, path::PathBuf, time::SystemTime};
 pub mod lang;
 pub mod policy;
 pub mod score;
+pub mod status;
 pub mod tracking;
 
 pub use arr_parse::NameClaims as ParsedRelease;
 pub use score::{Score, ScoreWeights};
+pub use status::{derive_series_status, SeriesStatus};
 
 macro_rules! id_type {
     ($name:ident) => {
diff --git a/crates/arr-core/src/status.rs b/crates/arr-core/src/status.rs
new file mode 100644
index 0000000..5e737c6
--- /dev/null
+++ b/crates/arr-core/src/status.rs
@@ -0,0 +1,206 @@
+use std::time::{Duration, SystemTime};
+
+use crate::{Episode, MediaState, Series};
+
+const AIRING_WINDOW: Duration = Duration::from_hours(14 * 24);
+
+/// A series' current state, derived from upstream metadata and local files.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum SeriesStatus {
+    Airing,
+    Incomplete,
+    Waiting,
+    Complete,
+    Ended,
+}
+
+/// Derives a series' status at `now` without persisting lifecycle intent.
+#[must_use]
+pub fn derive_series_status(
+    series: &Series,
+    episodes: &[Episode],
+    now: SystemTime,
+) -> SeriesStatus {
+    let wanted = episodes.iter().filter(|episode| episode.wanted);
+    let complete = wanted
+        .clone()
+        .all(|episode| episode.state == MediaState::Available);
+
+    if complete {
+        return if series.upstream_ended {
+            SeriesStatus::Ended
+        } else if series.auto_track {
+            SeriesStatus::Waiting
+        } else {
+            SeriesStatus::Complete
+        };
+    }
+
+    if wanted.clone().any(|episode| {
+        episode
+            .air_date
+            .is_some_and(|air_date| is_airing(air_date, now))
+    }) {
+        return SeriesStatus::Airing;
+    }
+
+    let window_end = now.checked_add(AIRING_WINDOW);
+    let only_future_or_undated_missing = wanted
+        .filter(|episode| episode.state != MediaState::Available)
+        .all(|episode| match (episode.air_date, window_end) {
+            (Some(air_date), Some(end)) => air_date > end,
+            (Some(_), None) => false,
+            (None, _) => true,
+        });
+
+    if only_future_or_undated_missing {
+        SeriesStatus::Waiting
+    } else {
+        SeriesStatus::Incomplete
+    }
+}
+
+fn is_airing(air_date: SystemTime, now: SystemTime) -> bool {
+    air_date
+        .duration_since(now)
+        .or_else(|_| now.duration_since(air_date))
+        .is_ok_and(|distance| distance <= AIRING_WINDOW)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{EpisodeId, Language, RootId, SeasonId, SeriesId, TitleOverrides};
+
+    const DAY: Duration = Duration::from_hours(24);
+
+    fn series(auto_track: bool, upstream_ended: bool) -> Series {
+        Series {
+            id: SeriesId(1),
+            tmdb_id: 82_728,
+            title: "Bluey".into(),
+            year: 2018,
+            original_language: Language::Other("en".into()),
+            root_id: RootId(1),
+            auto_track,
+            overrides: TitleOverrides::default(),
+            upstream_ended,
+            blocked: false,
+        }
+    }
+
+    fn episode(number: u16, air_date: Option<SystemTime>, state: MediaState) -> Episode {
+        Episode {
+            id: EpisodeId(i64::from(number)),
+            season_id: SeasonId(1),
+            number,
+            title: format!("Episode {number}"),
+            air_date,
+            wanted: true,
+            state,
+            search_attempts: 0,
+            last_searched_at: None,
+        }
+    }
+
+    #[test]
+    fn airing_when_a_wanted_episode_is_in_the_window() {
+        let now = SystemTime::UNIX_EPOCH + 100 * DAY;
+        for air_date in [now - 14 * DAY, now + 14 * DAY] {
+            let episodes = [episode(1, Some(air_date), MediaState::Missing)];
+            assert_eq!(
+                derive_series_status(&series(true, false), &episodes, now),
+                SeriesStatus::Airing
+            );
+        }
+
+        let just_outside = Duration::from_nanos(1);
+        let episodes = [episode(
+            1,
+            Some(now + 14 * DAY + just_outside),
+            MediaState::Missing,
+        )];
+        assert_eq!(
+            derive_series_status(&series(true, false), &episodes, now),
+            SeriesStatus::Waiting
+        );
+    }
+
+    #[test]
+    fn incomplete_when_an_aired_wanted_episode_is_missing() {
+        let now = SystemTime::UNIX_EPOCH + 100 * DAY;
+        let episodes = [episode(1, Some(now - 20 * DAY), MediaState::Missing)];
+
+        assert_eq!(
+            derive_series_status(&series(true, false), &episodes, now),
+            SeriesStatus::Incomplete
+        );
+    }
+
+    #[test]
+    fn waiting_when_the_next_wanted_episode_is_future_dated() {
+        let now = SystemTime::UNIX_EPOCH + 100 * DAY;
+        let episodes = [episode(1, Some(now + 30 * DAY), MediaState::Missing)];
+
+        assert_eq!(
+            derive_series_status(&series(true, false), &episodes, now),
+            SeriesStatus::Waiting
+        );
+    }
+
+    #[test]
+    fn complete_when_every_one_off_episode_is_available() {
+        let now = SystemTime::UNIX_EPOCH + 100 * DAY;
+        let episodes = [episode(1, Some(now), MediaState::Available)];
+
+        assert_eq!(
+            derive_series_status(&series(false, false), &episodes, now),
+            SeriesStatus::Complete
+        );
+    }
+
+    #[test]
+    fn ended_when_upstream_finished_and_everything_is_available() {
+        let now = SystemTime::UNIX_EPOCH + 100 * DAY;
+        let episodes = [episode(1, Some(now), MediaState::Available)];
+
+        assert_eq!(
+            derive_series_status(&series(true, true), &episodes, now),
+            SeriesStatus::Ended
+        );
+    }
+
+    #[test]
+    fn satisfied_one_off_grab_leaves_the_default_view() {
+        let now = SystemTime::UNIX_EPOCH + 100 * DAY;
+        let mut episodes = [episode(1, Some(now - 20 * DAY), MediaState::Missing)];
+        assert_eq!(
+            derive_series_status(&series(false, false), &episodes, now),
+            SeriesStatus::Incomplete
+        );
+
+        episodes[0].state = MediaState::Available;
+
+        assert_eq!(
+            derive_series_status(&series(false, false), &episodes, now),
+            SeriesStatus::Complete
+        );
+    }
+
+    #[test]
+    fn tracked_show_reappears_when_a_new_season_is_announced() {
+        let now = SystemTime::UNIX_EPOCH + 100 * DAY;
+        let mut episodes = vec![episode(1, Some(now - 30 * DAY), MediaState::Available)];
+        assert_eq!(
+            derive_series_status(&series(true, false), &episodes, now),
+            SeriesStatus::Waiting
+        );
+
+        episodes.push(episode(2, Some(now + 7 * DAY), MediaState::Missing));
+
+        assert_eq!(
+            derive_series_status(&series(true, false), &episodes, now),
+            SeriesStatus::Airing
+        );
+    }
+}