src/memories.rs

@@ -144,6 +144,10 @@ pub struct MemoriesRequest {
     /// Optional library filter. Accepts a library id (e.g. "1") or name
     /// (e.g. "main"). When omitted, results span all libraries.
     pub library: Option<String>,
+    /// Optional anchor date (`YYYY-MM-DD`, a calendar day in the owner's
+    /// display zone) to browse "on this day/week/month" relative to
+    /// instead of today. Omitted → today, unchanged behaviour.
+    pub reference_date: Option<String>,
 }
 
 #[derive(Debug, Serialize, Clone)]
@@ -175,6 +179,52 @@ pub struct MemoriesResponse {
     pub items: Vec<MemoryItem>,
 }
 
+/// Resolve the memories anchor: the `now_ts` that bounds the pre-filter
+/// window and the `today` that [`day_in_span`] matches against, both in
+/// the owner's display zone. With a reference date `D`, the window ends
+/// at the end of `D` (so a future `D` surfaces everything already taken,
+/// and the years-back lookback is anchored on `D`, not on now).
+pub fn memories_anchor(
+    reference_date: Option<NaiveDate>,
+    display_zone: chrono_tz::Tz,
+    now: DateTime<Utc>,
+) -> (i64, NaiveDate) {
+    let Some(d) = reference_date else {
+        let today = display_zone
+            .from_utc_datetime(&now.naive_utc())
+            .date_naive();
+        return (now.timestamp(), today);
+    };
+    // End of D = start of D+1 minus a second. Midnight can fall in a DST
+    // gap in a few zones; fall back to 01:00, then to a UTC reading.
+    let next = d.succ_opt().unwrap_or(d);
+    let start_of_next = [0, 1]
+        .iter()
+        .find_map(|h| {
+            display_zone
+                .from_local_datetime(&next.and_hms_opt(*h, 0, 0).expect("valid hour"))
+                .earliest()
+        })
+        .map(|dt| dt.timestamp())
+        .unwrap_or_else(|| {
+            next.and_hms_opt(0, 0, 0)
+                .expect("midnight")
+                .and_utc()
+                .timestamp()
+        });
+    (start_of_next - 1, d)
+}
+
+/// Parse the `/memories` `reference_date` param (`YYYY-MM-DD`).
+pub fn parse_reference_date(raw: Option<&str>) -> Result<Option<NaiveDate>, String> {
+    match raw.map(str::trim).filter(|s| !s.is_empty()) {
+        None => Ok(None),
+        Some(s) => NaiveDate::parse_from_str(s, "%Y-%m-%d")
+            .map(Some)
+            .map_err(|_| format!("invalid reference_date {s:?} (expected YYYY-MM-DD)")),
+    }
+}
+
 /// Epoch windows for the memories SQL pre-filter (ADR-0001).
 ///
 /// The span feature matches the same calendar position (month-day /
@@ -519,12 +569,21 @@ pub async fn list_memories(
     let display_zone =
         chrono_tz::Tz::from_str(&display_zone_name).unwrap_or(chrono_tz::Tz::America__New_York);
 
+    let reference_date = match parse_reference_date(q.reference_date.as_deref()) {
+        Ok(d) => d,
+        Err(msg) => {
+            warn!("Rejecting /memories request: {}", msg);
+            return HttpResponse::BadRequest().body(msg);
+        }
+    };
+
     let items = match gather_memory_items(
         &app_state,
         &exif_dao,
         span_mode,
         display_zone,
         q.library.as_deref(),
+        reference_date,
     ) {
         Ok(items) => items,
         Err(msg) => {
@@ -540,6 +599,10 @@ pub async fn list_memories(
             KeyValue::new("years_back", DEFAULT_YEARS_BACK.to_string()),
             KeyValue::new("result_count", items.len().to_string()),
             KeyValue::new("display_tz", display_zone_name),
+            KeyValue::new(
+                "reference_date",
+                reference_date.map_or_else(|| "today".to_string(), |d| d.to_string()),
+            ),
             KeyValue::new("excluded_dirs", format!("{:?}", app_state.excluded_dirs)),
         ],
     );
@@ -561,20 +624,20 @@ pub async fn list_memories(
 /// unconverted EXIF wall clock both land in the same day a photo taken
 /// locally did. The SQL pass is an interval pre-filter; exact span-day
 /// matching happens here in Rust via [`date_view`].
+///
+/// `reference_date` shifts "today" to another day in the display zone
+/// (see [`memories_anchor`]); `None` anchors on the real now.
 pub fn gather_memory_items(
     app_state: &AppState,
     exif_dao: &Mutex<Box<dyn ExifDao>>,
     span_mode: MemoriesSpan,
     display_zone: chrono_tz::Tz,
     library_param: Option<&str>,
+    reference_date: Option<NaiveDate>,
 ) -> Result<Vec<MemoryItem>, String> {
     let years_back: i64 = DEFAULT_YEARS_BACK as i64;
 
-    let now = Utc::now();
-    let now_ts = now.timestamp();
-    let today_d = display_zone
-        .from_utc_datetime(&now.naive_utc())
-        .date_naive();
+    let (now_ts, today_d) = memories_anchor(reference_date, display_zone, Utc::now());
     // The SQL pass is a coarse pre-filter over the FULL years-back window
     // (not the current span window) because this feature matches the same
     // month-day / week / month across every past year; [`day_in_span`] does
@@ -583,8 +646,8 @@ pub fn gather_memory_items(
     let server_zone = crate::camera_tz::server_zone();
 
     debug!(
-        "gather_memory_items: span={:?} display_zone={:?} years_back={}",
-        span_mode, display_zone, years_back
+        "gather_memory_items: span={:?} display_zone={:?} years_back={} today={}",
+        span_mode, display_zone, years_back, today_d
     );
 
     let library = crate::libraries::resolve_library_param_state(app_state, library_param)?;
@@ -1241,6 +1304,60 @@ mod tests {
         assert!(ulo <= clo && chi <= uhi);
     }
 
+    #[test]
+    fn memories_anchor_defaults_to_now_in_display_zone() {
+        let zone = chrono_tz::Tz::America__New_York;
+        // 2024-07-05 02:00 UTC is still Jul 4 in New York.
+        let now = Utc.with_ymd_and_hms(2024, 7, 5, 2, 0, 0).unwrap();
+        let (ts, today) = memories_anchor(None, zone, now);
+        assert_eq!(ts, now.timestamp());
+        assert_eq!(today, NaiveDate::from_ymd_opt(2024, 7, 4).unwrap());
+    }
+
+    #[test]
+    fn memories_anchor_reference_date_ends_at_end_of_that_day() {
+        let zone = chrono_tz::Tz::America__New_York;
+        let d = NaiveDate::from_ymd_opt(2015, 3, 10).unwrap();
+        let (ts, today) = memories_anchor(Some(d), zone, Utc::now());
+        assert_eq!(today, d);
+        // 2015-03-10 23:59:59 EDT (DST began Mar 8) = 03:59:59 UTC next day.
+        assert_eq!(
+            ts,
+            Utc.with_ymd_and_hms(2015, 3, 11, 3, 59, 59)
+                .unwrap()
+                .timestamp()
+        );
+    }
+
+    #[test]
+    fn memories_anchor_survives_midnight_dst_gap() {
+        // America/Santiago springs forward at 00:00 → 01:00 (2023-09-03).
+        let zone = chrono_tz::Tz::America__Santiago;
+        let d = NaiveDate::from_ymd_opt(2023, 9, 2).unwrap();
+        let (ts, today) = memories_anchor(Some(d), zone, Utc::now());
+        assert_eq!(today, d);
+        // Sep 3 01:00 -03 = 04:00 UTC; minus one second.
+        assert_eq!(
+            ts,
+            Utc.with_ymd_and_hms(2023, 9, 3, 3, 59, 59)
+                .unwrap()
+                .timestamp()
+        );
+    }
+
+    #[test]
+    fn parse_reference_date_accepts_absent_empty_and_iso() {
+        assert_eq!(parse_reference_date(None), Ok(None));
+        assert_eq!(parse_reference_date(Some("")), Ok(None));
+        assert_eq!(
+            parse_reference_date(Some("2015-03-10")),
+            Ok(NaiveDate::from_ymd_opt(2015, 3, 10))
+        );
+        assert!(parse_reference_date(Some("2015-13-01")).is_err());
+        assert!(parse_reference_date(Some("03/10/2015")).is_err());
+        assert!(parse_reference_date(Some("2015-02-30")).is_err());
+    }
+
     #[test]
     fn day_in_span_day_and_month() {
         let today = NaiveDate::from_ymd_opt(2024, 7, 4).unwrap();
@@ -1442,8 +1559,9 @@ mod tests {
             seed_row(&mut dao, "unconv-vid.mp4", vid_legacy, "exiftool");
 
             let exif_mutex: Mutex<Box<dyn ExifDao>> = Mutex::new(Box::new(dao));
-            let items = gather_memory_items(&state, &exif_mutex, MemoriesSpan::Month, zone, None)
-                .expect("gather");
+            let items =
+                gather_memory_items(&state, &exif_mutex, MemoriesSpan::Month, zone, None, None)
+                    .expect("gather");
             let by_path = |p: &str| items.iter().find(|it| it.path == p);
 
             // All three rows group into the same owner month (AC-2/AC-3).
@@ -1501,6 +1619,57 @@ mod tests {
             assert_eq!(vid.created, Some(vid_expected));
         }
 
+        /// Seed a converted row (true instant known), so grouping is
+        /// independent of the server zone's legacy convention.
+        fn seed_converted(dao: &mut SqliteExifDao, rel: &str, instant: NaiveDateTime) {
+            let ts = instant.and_utc().timestamp();
+            seed_row(dao, rel, ts, "exif");
+            dao.backfill_date_taken(1, rel, ts, "exif", Some(ts), None, Some("utc_direct"))
+                .expect("convert row");
+        }
+
+        #[actix_rt::test]
+        async fn memories_reference_date_anchors_day_and_lookback() {
+            let state = AppState::test_state();
+            let zone = chrono_tz::Tz::America__New_York;
+            let noon = |y: i32, m: u32, d: u32| {
+                NaiveDate::from_ymd_opt(y, m, d)
+                    .unwrap()
+                    .and_hms_opt(12, 0, 0)
+                    .unwrap()
+            };
+
+            let mut dao = SqliteExifDao::from_connection(in_memory_db_connection());
+            seed_converted(&mut dao, "2010-same-day.jpg", noon(2010, 3, 10));
+            seed_converted(&mut dao, "1996-same-day.jpg", noon(1996, 3, 10));
+            seed_converted(&mut dao, "1994-too-old.jpg", noon(1994, 3, 10));
+            seed_converted(&mut dao, "2016-after-ref.jpg", noon(2016, 3, 10));
+            seed_converted(&mut dao, "2010-next-day.jpg", noon(2010, 3, 11));
+            let exif_mutex: Mutex<Box<dyn ExifDao>> = Mutex::new(Box::new(dao));
+
+            let paths = |d: NaiveDate| -> Vec<String> {
+                gather_memory_items(&state, &exif_mutex, MemoriesSpan::Day, zone, None, Some(d))
+                    .expect("gather")
+                    .into_iter()
+                    .map(|m| m.path)
+                    .collect()
+            };
+
+            // Past reference date: same month-day, within 20 years
+            // *before D*, nothing after D.
+            assert_eq!(
+                paths(NaiveDate::from_ymd_opt(2015, 3, 10).unwrap()),
+                vec!["1996-same-day.jpg", "2010-same-day.jpg"]
+            );
+
+            // Future reference date: lookback anchored on D, so 2016 is
+            // in range and 1996/2010 have aged out of the 20-year window.
+            assert_eq!(
+                paths(NaiveDate::from_ymd_opt(2030, 3, 10).unwrap()),
+                vec!["2016-after-ref.jpg"]
+            );
+        }
+
         /// AC-1 (response shape): the serialized `/memories` item carries
         /// the new-contract triple as explicit fields — null while the row
         /// is unconverted.

src/reels/selector.rs

@@ -296,6 +296,8 @@ pub fn resolve(
                 *span,
                 zone,
                 library.as_deref(),
+                // Reels are always "now" (MVP): no reference date.
+                None,
             )?;
 
             // Split into photos and video clips; anything that's neither is