lasso bugs

src-tauri/src/commands.rs

@@ -7232,3 +7232,358 @@ pub async fn export_bboxes_to_json(
     tokio::fs::write(&path, body).await.map_err(|e| e.to_string())?;
     Ok(n)
 }
+
+// ---------- equalize_along_road -------------------------------------------
+//
+// Redistribute a set of "uniformly-spaced" assets (e.g. streetlights) so the
+// arc-length spacing along the nearest OSM road is constant between two
+// anchors. Returns a proposal (no DB writes) so the frontend can show the
+// gap-anomaly report and let the user confirm before applying.
+//
+// Why arc-length not Euclidean: on curves, equal Euclidean spacing pushes
+// markers off the road. Arc-length spacing keeps them on the curve.
+// Lateral offset uses the avg perpendicular distance of the two anchors from
+// the road centerline, so left-side stays left and right-side stays right
+// even through bends.
+
+#[derive(Debug, Serialize)]
+pub struct EqualizationProposal {
+    pub asset_id: i64,
+    pub orig_lat: f64,
+    pub orig_lng: f64,
+    pub new_lat: f64,
+    pub new_lng: f64,
+    pub displacement_m: f64,
+}
+
+#[derive(Debug, Serialize)]
+pub struct GapAnomaly {
+    pub before_id: i64,
+    pub after_id: i64,
+    pub gap_m: f64,
+    pub expected_missing: i64,
+}
+
+#[derive(Debug, Serialize)]
+pub struct EqualizationResult {
+    pub proposals: Vec<EqualizationProposal>,
+    pub anomalies: Vec<GapAnomaly>,
+    pub median_gap_m: f64,
+    pub arc_length_m: f64,
+    pub road_id: i64,
+    pub lateral_offset_m: f64,
+}
+
+/// Project (lng, lat) onto every segment of `line`, return the closest
+/// (arc_position_m, snap_lng, snap_lat, signed_perpendicular_m). Sign of
+/// perpendicular: cross product (segment × asset-from-snap) — positive ⇒
+/// asset is to the left of the segment heading.
+fn project_onto_polyline(
+    line: &LineString<f64>,
+    lng: f64,
+    lat: f64,
+) -> (f64, f64, f64, f64) {
+    let pt = Point::new(lng, lat);
+    let mut best_dist = f64::INFINITY;
+    let mut best_arc = 0.0;
+    let mut best_x = lng;
+    let mut best_y = lat;
+    let mut best_dx = 0.0_f64;
+    let mut best_dy = 0.0_f64;
+    let mut cumulative = 0.0;
+    for seg in line.lines() {
+        let snapped = match LineString(vec![seg.start, seg.end]).closest_point(&pt) {
+            Closest::SinglePoint(p) | Closest::Intersection(p) => p,
+            Closest::Indeterminate => continue,
+        };
+        let d = Geodesic.distance(pt, snapped);
+        let seg_len = Geodesic.distance(
+            Point::new(seg.start.x, seg.start.y),
+            Point::new(seg.end.x, seg.end.y),
+        );
+        if d < best_dist {
+            best_dist = d;
+            best_x = snapped.x();
+            best_y = snapped.y();
+            best_dx = seg.end.x - seg.start.x;
+            best_dy = seg.end.y - seg.start.y;
+            // Arc from seg start to snapped point. Use straight-line ratio in
+            // lat/lng space — accurate for the short segments OSM produces.
+            let t_dx = snapped.x() - seg.start.x;
+            let t_dy = snapped.y() - seg.start.y;
+            let raw_dx = seg.end.x - seg.start.x;
+            let raw_dy = seg.end.y - seg.start.y;
+            let raw_len_sq = raw_dx * raw_dx + raw_dy * raw_dy;
+            let t = if raw_len_sq > 1e-18 {
+                ((t_dx * raw_dx + t_dy * raw_dy) / raw_len_sq).clamp(0.0, 1.0)
+            } else {
+                0.0
+            };
+            best_arc = cumulative + t * seg_len;
+        }
+        cumulative += seg_len;
+    }
+    // Signed perpendicular distance in metres.
+    let m_per_lat = 111_320.0_f64;
+    let m_per_lng = 111_320.0_f64
+        * (best_y * std::f64::consts::PI / 180.0).cos().abs().max(1e-6);
+    let dx_m = best_dx * m_per_lng;
+    let dy_m = best_dy * m_per_lat;
+    let ax_m = (lng - best_x) * m_per_lng;
+    let ay_m = (lat - best_y) * m_per_lat;
+    let len = (dx_m * dx_m + dy_m * dy_m).sqrt().max(1e-9);
+    let cross = dx_m * ay_m - dy_m * ax_m;
+    let perp_signed = cross / len;
+    (best_arc, best_x, best_y, perp_signed)
+}
+
+/// Return (lng, lat, tangent_dx_lng, tangent_dy_lat) of the point at
+/// `target_arc` metres along `line`. None if `target_arc` is past the end.
+fn point_at_arc(
+    line: &LineString<f64>,
+    target_arc: f64,
+) -> Option<(f64, f64, f64, f64)> {
+    let mut cumulative = 0.0;
+    for seg in line.lines() {
+        let seg_len = Geodesic.distance(
+            Point::new(seg.start.x, seg.start.y),
+            Point::new(seg.end.x, seg.end.y),
+        );
+        if cumulative + seg_len + 1e-6 >= target_arc {
+            let t = if seg_len > 1e-6 {
+                (target_arc - cumulative) / seg_len
+            } else {
+                0.0
+            };
+            let lng = seg.start.x + t * (seg.end.x - seg.start.x);
+            let lat = seg.start.y + t * (seg.end.y - seg.start.y);
+            return Some((lng, lat, seg.end.x - seg.start.x, seg.end.y - seg.start.y));
+        }
+        cumulative += seg_len;
+    }
+    None
+}
+
+async fn find_nearest_road_id(
+    pool: &sqlx::SqlitePool,
+    lat: f64,
+    lng: f64,
+    max_d: f64,
+) -> Result<(i64, LineString<f64>), String> {
+    let pad_lat = max_d / 111_320.0;
+    let pad_lng = max_d
+        / (111_320.0
+            * (lat * std::f64::consts::PI / 180.0).cos().abs().max(1e-6));
+    let rows: Vec<(i64, String)> = sqlx::query_as(
+        "SELECT r.id, r.geojson
+         FROM roads r JOIN roads_rtree x ON x.id = r.id
+         WHERE x.max_lat >= ? AND x.min_lat <= ?
+           AND x.max_lng >= ? AND x.min_lng <= ?
+           AND COALESCE(r.snap_ignored, 0) = 0",
+    )
+    .bind(lat - pad_lat)
+    .bind(lat + pad_lat)
+    .bind(lng - pad_lng)
+    .bind(lng + pad_lng)
+    .fetch_all(pool)
+    .await
+    .map_err(|e| e.to_string())?;
+    let pt = Point::new(lng, lat);
+    let mut best: Option<(f64, i64, LineString<f64>)> = None;
+    for (id, gj) in rows {
+        let Some(line) = parse_linestring(&gj) else { continue };
+        let mut min_d = f64::INFINITY;
+        for seg in line.lines() {
+            let snapped = match LineString(vec![seg.start, seg.end]).closest_point(&pt) {
+                Closest::SinglePoint(p) | Closest::Intersection(p) => p,
+                Closest::Indeterminate => continue,
+            };
+            let d = Geodesic.distance(pt, snapped);
+            if d < min_d {
+                min_d = d;
+            }
+        }
+        if min_d.is_finite()
+            && min_d <= max_d
+            && best.as_ref().map(|b| min_d < b.0).unwrap_or(true)
+        {
+            best = Some((min_d, id, line));
+        }
+    }
+    let (_, id, line) =
+        best.ok_or_else(|| format!("no road within {:.0} m of anchor", max_d))?;
+    Ok((id, line))
+}
+
+#[tauri::command]
+pub async fn equalize_along_road(
+    anchor_a_id: i64,
+    anchor_b_id: i64,
+    asset_ids: Vec<i64>,
+    max_road_distance_m: Option<f64>,
+    state: State<'_, AppState>,
+) -> Result<EqualizationResult, String> {
+    let max_d = max_road_distance_m.unwrap_or(50.0);
+    if anchor_a_id == anchor_b_id {
+        return Err("two distinct anchors required".into());
+    }
+    if asset_ids.is_empty() {
+        return Err("no assets selected to redistribute".into());
+    }
+
+    // Fetch positions.
+    let mut all_ids: Vec<i64> = Vec::with_capacity(2 + asset_ids.len());
+    all_ids.push(anchor_a_id);
+    all_ids.push(anchor_b_id);
+    all_ids.extend(&asset_ids);
+    let placeholders = vec!["?"; all_ids.len()].join(",");
+    let sql = format!(
+        "SELECT id, lat, lng FROM assets WHERE id IN ({}) AND deleted = 0",
+        placeholders
+    );
+    let mut q = sqlx::query_as::<_, (i64, Option<f64>, Option<f64>)>(&sql);
+    for id in &all_ids {
+        q = q.bind(id);
+    }
+    let rows = q.fetch_all(&state.pool).await.map_err(|e| e.to_string())?;
+    let mut pos: std::collections::HashMap<i64, (f64, f64)> =
+        std::collections::HashMap::new();
+    for (id, lat, lng) in rows {
+        if let (Some(la), Some(lo)) = (lat, lng) {
+            pos.insert(id, (la, lo));
+        }
+    }
+    let (a_lat, a_lng) = *pos
+        .get(&anchor_a_id)
+        .ok_or("anchor A has no position")?;
+    let (b_lat, b_lng) = *pos
+        .get(&anchor_b_id)
+        .ok_or("anchor B has no position")?;
+
+    // Locate the road for each anchor; require both on the same OSM way.
+    let (road_a_id, line_a) = find_nearest_road_id(&state.pool, a_lat, a_lng, max_d).await?;
+    let (road_b_id, _) = find_nearest_road_id(&state.pool, b_lat, b_lng, max_d).await?;
+    if road_a_id != road_b_id {
+        return Err(format!(
+            "anchors are on different OSM roads ({} vs {}). Multi-way stitching isn't supported yet — drop a road that covers both anchors.",
+            road_a_id, road_b_id
+        ));
+    }
+    let line = line_a;
+
+    // Project anchors + assets.
+    let proj_a = project_onto_polyline(&line, a_lng, a_lat);
+    let proj_b = project_onto_polyline(&line, b_lng, b_lat);
+    let (mut s_lo, mut s_hi) = (proj_a.0, proj_b.0);
+    let lo_id = if s_lo <= s_hi {
+        anchor_a_id
+    } else {
+        std::mem::swap(&mut s_lo, &mut s_hi);
+        anchor_b_id
+    };
+    let hi_id = if lo_id == anchor_a_id { anchor_b_id } else { anchor_a_id };
+    let arc_length = s_hi - s_lo;
+    if arc_length < 1.0 {
+        return Err("anchors are within 1 m on the road — nothing to redistribute".into());
+    }
+
+    let mut asset_projs: Vec<(i64, f64, f64, f64)> = Vec::new();
+    for id in &asset_ids {
+        if *id == anchor_a_id || *id == anchor_b_id {
+            continue;
+        }
+        let Some((la, lo)) = pos.get(id).copied() else { continue };
+        let p = project_onto_polyline(&line, lo, la);
+        // Allow a 1 m slop so an asset sitting exactly on an anchor counts.
+        if p.0 >= s_lo - 1.0 && p.0 <= s_hi + 1.0 {
+            asset_projs.push((*id, p.0, la, lo));
+        }
+    }
+    asset_projs.sort_by(|a, b| a.1.partial_cmp(&b.1).unwrap_or(std::cmp::Ordering::Equal));
+    if asset_projs.is_empty() {
+        return Err(
+            "none of the selected assets project onto the road segment between the two anchors"
+                .into(),
+        );
+    }
+
+    // Build the full ordered sequence with anchors at both ends for gap stats.
+    let mut sequence: Vec<(i64, f64)> = Vec::with_capacity(asset_projs.len() + 2);
+    sequence.push((lo_id, s_lo));
+    for ap in &asset_projs {
+        sequence.push((ap.0, ap.1));
+    }
+    sequence.push((hi_id, s_hi));
+
+    let mut gaps: Vec<f64> = Vec::with_capacity(sequence.len() - 1);
+    for i in 0..sequence.len() - 1 {
+        gaps.push((sequence[i + 1].1 - sequence[i].1).max(0.0));
+    }
+    let mut sorted_gaps = gaps.clone();
+    sorted_gaps.sort_by(|a, b| a.partial_cmp(b).unwrap_or(std::cmp::Ordering::Equal));
+    let median_gap = sorted_gaps[sorted_gaps.len() / 2];
+
+    // Anomaly detection: a gap is flagged when it's much larger than the
+    // median AND larger than a minimum absolute floor (so a 0.5 m → 1 m gap
+    // doesn't spam warnings).
+    const ANOMALY_RATIO: f64 = 1.8;
+    const MIN_GAP_FOR_ANOMALY_M: f64 = 5.0;
+    let mut anomalies: Vec<GapAnomaly> = Vec::new();
+    for (i, &g) in gaps.iter().enumerate() {
+        if g > median_gap * ANOMALY_RATIO && g > MIN_GAP_FOR_ANOMALY_M && median_gap > 1e-3 {
+            let expected_missing = ((g / median_gap).round() as i64 - 1).max(1);
+            anomalies.push(GapAnomaly {
+                before_id: sequence[i].0,
+                after_id: sequence[i + 1].0,
+                gap_m: g,
+                expected_missing,
+            });
+        }
+    }
+
+    // Average signed perpendicular offset of the anchors — used as the
+    // lateral offset for every redistributed point. Curvature is handled by
+    // computing the perpendicular direction PER point at its new tangent.
+    let lateral_offset = (proj_a.3 + proj_b.3) / 2.0;
+
+    // Equalize: N intermediate points, equally spaced between s_lo and s_hi.
+    let n = asset_projs.len();
+    let step = arc_length / (n as f64 + 1.0);
+    let mut proposals: Vec<EqualizationProposal> = Vec::with_capacity(n);
+    for (i, ap) in asset_projs.iter().enumerate() {
+        let new_arc = s_lo + step * (i as f64 + 1.0);
+        let Some((cx, cy, dx_lng, dy_lat)) = point_at_arc(&line, new_arc) else {
+            continue;
+        };
+        let m_per_lat = 111_320.0_f64;
+        let m_per_lng = 111_320.0_f64
+            * (cy * std::f64::consts::PI / 180.0).cos().abs().max(1e-6);
+        let dx_m = dx_lng * m_per_lng;
+        let dy_m = dy_lat * m_per_lat;
+        let len = (dx_m * dx_m + dy_m * dy_m).sqrt().max(1e-9);
+        // Left-normal of the tangent (matches the sign convention of
+        // project_onto_polyline so positive perp keeps the same side).
+        let nx = -dy_m / len;
+        let ny = dx_m / len;
+        let new_lng = cx + nx * lateral_offset / m_per_lng;
+        let new_lat = cy + ny * lateral_offset / m_per_lat;
+        let displacement_m = haversine_m((ap.2, ap.3), (new_lat, new_lng));
+        proposals.push(EqualizationProposal {
+            asset_id: ap.0,
+            orig_lat: ap.2,
+            orig_lng: ap.3,
+            new_lat,
+            new_lng,
+            displacement_m,
+        });
+    }
+
+    Ok(EqualizationResult {
+        proposals,
+        anomalies,
+        median_gap_m: median_gap,
+        arc_length_m: arc_length,
+        road_id: road_a_id,
+        lateral_offset_m: lateral_offset,
+    })
+}

src-tauri/src/lib.rs

@@ -8,7 +8,7 @@ use commands::{
     import_osm_geojson,
     import_range_assets, list_assets, read_video_polylines_json, list_recent_actions, merge_polylines, reset_assets_to_original,
     read_metadata_polyline, redo_action, reset_database, snap_assets_in_bbox,
-    add_class, auto_link_in_polygon, bulk_translate, clear_assets_by_type,
+    add_class, auto_link_in_polygon, bulk_translate, clear_assets_by_type, equalize_along_road,
     clear_osm_roads, clear_scope_polygons, data_source_counts, change_assets_side, clear_link, clear_manual_scope,
     create_osm_road, create_user, delete_road_section, delete_road_vertices,
     delete_roads_in_lasso, set_link, simplify_road,
@@ -124,7 +124,8 @@ pub fn run() {
             clear_asset_bbox,
             export_bboxes_to_json,
             set_link,
-            clear_link
+            clear_link,
+            equalize_along_road
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");

src/App.tsx

@@ -584,6 +584,10 @@ function AppShell({
   }, [autoLinkMaxM]);
   const [lassoListOpen, setLassoListOpen] = useState<boolean>(false);
   const [showDeleted, setShowDeleted] = useState<boolean>(false);
+  // '?' opens a cheat-sheet modal listing every keyboard shortcut. We track
+  // it as plain boolean state so the same handler can toggle on key press
+  // and close on backdrop click.
+  const [showShortcutsHelp, setShowShortcutsHelp] = useState<boolean>(false);
   // Pulse animation for "Blink modified points". A simple bool toggle drives
   // a setInterval in an effect; the tick is plumbed through to MapView so its
   // dedicated overlay layer redraws every ~600 ms with alternating opacity.
@@ -1209,6 +1213,112 @@ function AppShell({
         toggleOsmEditModeRef.current();
         return;
       }
+      // '?' (or Shift+/ on US layouts) opens the keyboard cheat-sheet.
+      // Toggles, so pressing again closes it. Always allowed except when
+      // typing into a text field.
+      if (e.key === "?" || (e.key === "/" && e.shiftKey)) {
+        const target = e.target as HTMLElement | null;
+        const tag = target?.tagName;
+        if (tag === "INPUT" || tag === "TEXTAREA" || target?.isContentEditable) {
+          return;
+        }
+        e.preventDefault();
+        setShowShortcutsHelp((v) => !v);
+        return;
+      }
+      // 'A' toggles the selected asset as a GPS-correction anchor. Same
+      // toggle the "Mark as anchor" button does, just one-tap: pick the
+      // asset, press A, drag it to the right spot, press Distribute.
+      if (
+        (e.key === "a" || e.key === "A") &&
+        selectedAsset &&
+        !osmEditMode
+      ) {
+        const target = e.target as HTMLElement | null;
+        const tag = target?.tagName;
+        if (tag === "INPUT" || tag === "TEXTAREA" || target?.isContentEditable) {
+          return;
+        }
+        if (e.ctrlKey || e.metaKey || e.altKey) return;
+        e.preventDefault();
+        setAnchors((prev) => {
+          const next = new Map(prev);
+          if (next.has(selectedAsset.id)) {
+            next.delete(selectedAsset.id);
+            showToast("Anchor cleared");
+          } else if (
+            selectedAsset.lat !== null &&
+            selectedAsset.lng !== null
+          ) {
+            next.set(selectedAsset.id, {
+              origLat: selectedAsset.lat,
+              origLng: selectedAsset.lng,
+              rowId: selectedAsset.row_id,
+            });
+            showToast("Marked as anchor");
+          }
+          return next;
+        });
+        return;
+      }
+      // Auto-link shortcuts. Require an active lasso selection (and its
+      // synthesized polygon — circle/bbox/polygon all set lassoPolygonPoints
+      // now) so we know the region to link inside. Modifiers pick the
+      // splitter: plain L = side (Left↔Right), Shift+L = by video,
+      // Alt+L = nearest (no split).
+      if (
+        (e.key === "l" || e.key === "L") &&
+        lassoSelected &&
+        lassoPolygonPoints &&
+        lassoPolygonPoints.length >= 3
+      ) {
+        const target = e.target as HTMLElement | null;
+        const tag = target?.tagName;
+        if (tag === "INPUT" || tag === "TEXTAREA" || target?.isContentEditable) {
+          return;
+        }
+        if (e.ctrlKey || e.metaKey) return;
+        e.preventDefault();
+        const mode: "side" | "video" | "none" = e.altKey
+          ? "none"
+          : e.shiftKey
+            ? "video"
+            : "side";
+        void handleAutoLink(mode);
+        return;
+      }
+      // 'K' clears links on every asset in the active lasso selection.
+      // Mirrors the "Clear links" button so it's a 1-tap undo after a
+      // mis-linked auto-link run.
+      if (
+        (e.key === "k" || e.key === "K") &&
+        lassoSelected &&
+        lassoSelected.ids.length > 0
+      ) {
+        const target = e.target as HTMLElement | null;
+        const tag = target?.tagName;
+        if (tag === "INPUT" || tag === "TEXTAREA" || target?.isContentEditable) {
+          return;
+        }
+        if (e.ctrlKey || e.metaKey || e.altKey) return;
+        e.preventDefault();
+        const ids = lassoSelected.ids.slice();
+        (async () => {
+          let n = 0;
+          for (const id of ids) {
+            try {
+              await invoke("clear_link", { id });
+              n++;
+            } catch {
+              /* asset wasn't linked; ignore */
+            }
+          }
+          setStatus(`Cleared links on ${n} asset(s)`);
+          showToast(`Cleared ${n} link(s)`);
+          await refreshAfterMutation();
+        })();
+        return;
+      }
       // 'R' / 'r' opens the rename modal for the currently selected asset.
       // Input-guard pattern matches the other shortcuts.
       if (e.key === "r" || e.key === "R") {
@@ -1339,6 +1449,11 @@ function AppShell({
         return;
       }
       if (e.key !== "Escape") return;
+      if (showShortcutsHelp) {
+        e.preventDefault();
+        setShowShortcutsHelp(false);
+        return;
+      }
       if (lensActive) {
         e.preventDefault();
         setLensActive(false);
@@ -1384,7 +1499,7 @@ function AppShell({
     };
     window.addEventListener("keydown", handler);
     return () => window.removeEventListener("keydown", handler);
-  }, [drawRoadMode, editingRoadId, linkPickMode, rightClickFirstId, lassoMode, selectedLink, selectedMetadataVideo, gotoPin, osmEditMode, markedVertices, focusedVideo, selectedRoadIds, lensActive, selectedAsset, selectedAssetId, popupEnabled, multiSelectedIds]);
+  }, [drawRoadMode, editingRoadId, linkPickMode, rightClickFirstId, lassoMode, selectedLink, selectedMetadataVideo, gotoPin, osmEditMode, markedVertices, focusedVideo, selectedRoadIds, lensActive, selectedAsset, selectedAssetId, popupEnabled, multiSelectedIds, lassoSelected, lassoPolygonPoints, showShortcutsHelp]);
 
   // Image prefetch: when an asset is selected, warm the browser cache for its
   // immediate neighbours so [/] navigation feels instant.
@@ -2610,6 +2725,21 @@ function AppShell({
         if (haversine(center, [a.lng, a.lat]) <= radius) ids.push(a.id);
       }
       label = `circle r=${radius.toFixed(0)} m`;
+      // Stash a polygon approximation of the circle so polygon-only actions
+      // (Auto-link, anchor-Distribute) light up for circle lasso too. Same
+      // 64-vertex approximation we already use in the OSM-edit-mode lasso.
+      const m_per_lat = 111_320;
+      const m_per_lng = 111_320 * Math.cos(toRad(center[1]));
+      const N = 64;
+      const poly: Array<[number, number]> = [];
+      for (let i = 0; i < N; i++) {
+        const a = (i / N) * Math.PI * 2;
+        poly.push([
+          center[0] + (radius * Math.cos(a)) / m_per_lng,
+          center[1] + (radius * Math.sin(a)) / m_per_lat,
+        ]);
+      }
+      setLassoPolygonPoints(poly);
     } else if (shape === "rect") {
       const [a, b] = points;
       const minLng = Math.min(a[0], b[0]);
@@ -2632,6 +2762,13 @@ function AppShell({
           ids.push(x.id);
       }
       label = "bbox";
+      // Bbox as a 4-vertex polygon for Auto-link + region-scoped actions.
+      setLassoPolygonPoints([
+        [minLng, minLat],
+        [maxLng, minLat],
+        [maxLng, maxLat],
+        [minLng, maxLat],
+      ]);
     } else {
       // polygon: ray-casting test
       const verts = points;
@@ -2821,15 +2958,23 @@ function AppShell({
     anchorList.sort((a, b) => naturalCompare(a.rowId, b.rowId));
     const anchorIds = new Set(anchorList.map((a) => a.id));
 
-    // Build the corrections payload for every visible filtered asset that
+    // Build the corrections payload. When a lasso selection is active we
-    // isn't itself an anchor (anchors already moved, no need to re-translate).
+    // scope to those ids — anchor moves are meant to correct the assets the
+    // user explicitly bracketed, NOT every other point that happens to be
+    // visible. Without an active lasso the legacy behavior (all live filtered
+    // assets) still applies for one-anchor uniform shifts.
+    const lassoIdSet =
+      lassoSelected && lassoSelected.ids.length > 0
+        ? new Set(lassoSelected.ids)
+        : null;
     const targets = filteredAssets
       .filter(
         (a) =>
           a.deleted === 0 &&
           a.lat !== null &&
           a.lng !== null &&
-          !anchorIds.has(a.id),
+          !anchorIds.has(a.id) &&
+          (lassoIdSet === null || lassoIdSet.has(a.id)),
       )
       .slice()
       .sort((a, b) => naturalCompare(a.row_id, b.row_id));
@@ -2938,6 +3083,98 @@ function AppShell({
     }
   }
 
+  type EqualizationProposal = {
+    asset_id: number;
+    orig_lat: number;
+    orig_lng: number;
+    new_lat: number;
+    new_lng: number;
+    displacement_m: number;
+  };
+  type GapAnomaly = {
+    before_id: number;
+    after_id: number;
+    gap_m: number;
+    expected_missing: number;
+  };
+  type EqualizationResult = {
+    proposals: EqualizationProposal[];
+    anomalies: GapAnomaly[];
+    median_gap_m: number;
+    arc_length_m: number;
+    road_id: number;
+    lateral_offset_m: number;
+  };
+  const [equalizeReport, setEqualizeReport] =
+    useState<EqualizationResult | null>(null);
+
+  // Convert an EqualizationResult into bulk_translate corrections (id, dlat,
+  // dlng). Shared between the auto-apply path (no anomalies) and the
+  // user-confirms path inside the modal.
+  async function applyEqualization(result: EqualizationResult) {
+    const corrections = result.proposals.map((p) => ({
+      id: p.asset_id,
+      dlat: p.new_lat - p.orig_lat,
+      dlng: p.new_lng - p.orig_lng,
+    }));
+    if (corrections.length === 0) {
+      showToast("Nothing to apply");
+      return;
+    }
+    const n = await invoke<number>("bulk_translate", { corrections });
+    setStatus(
+      `Equalized ${n} asset(s) along road #${result.road_id} — arc ${result.arc_length_m.toFixed(0)} m, spacing ${(result.arc_length_m / (corrections.length + 1)).toFixed(1)} m`,
+    );
+    showToast(`Equalized ${n} asset(s)`);
+    await refreshAfterMutation();
+  }
+
+  async function handleEqualizeAlongRoad() {
+    if (anchors.size !== 2) {
+      setStatus("Mark exactly two anchors (press A on each) before equalizing.");
+      return;
+    }
+    if (!lassoSelected || lassoSelected.ids.length === 0) {
+      setStatus("Lasso the assets you want to redistribute between the anchors.");
+      return;
+    }
+    const anchorIds = Array.from(anchors.keys());
+    const [anchorAId, anchorBId] = anchorIds;
+    // Drop anchor ids from the target list — anchors stay where the user
+    // moved them; equalize redistributes the others.
+    const assetIds = lassoSelected.ids.filter(
+      (id) => id !== anchorAId && id !== anchorBId,
+    );
+    if (assetIds.length === 0) {
+      setStatus("Lasso must include at least one non-anchor asset.");
+      return;
+    }
+    setBusy(true);
+    try {
+      const result = await invoke<EqualizationResult>(
+        "equalize_along_road",
+        {
+          anchorAId,
+          anchorBId,
+          assetIds,
+          maxRoadDistanceM: 50,
+        },
+      );
+      if (result.anomalies.length === 0) {
+        // No discrepancies → apply immediately.
+        await applyEqualization(result);
+      } else {
+        // Show the gap report so the user can decide.
+        setEqualizeReport(result);
+      }
+    } catch (e) {
+      setStatus(`Equalize failed: ${e}`);
+      showToast(`Equalize failed: ${e}`);
+    } finally {
+      setBusy(false);
+    }
+  }
+
   async function handleAutoLink(splitBy: "side" | "video" | "none") {
     if (!lassoPolygonPoints || lassoPolygonPoints.length < 3) {
       setStatus("Use the polygon lasso to define a region first.");
@@ -3957,6 +4194,15 @@ function AppShell({
       >
         ⚙
       </button>
+      <button
+        className="gear-btn"
+        onClick={() => setShowShortcutsHelp(true)}
+        aria-label="Keyboard shortcuts"
+        title="Keyboard shortcuts  (?)"
+        style={{ right: 96 }}
+      >
+        ?
+      </button>
       <div
         className="user-chip"
         title={`Logged in as ${currentUser.displayName} (@${currentUser.username}). Click to logout.`}
@@ -3976,7 +4222,26 @@ function AppShell({
           >
             ✕
           </button>
-          <h3>Filters</h3>
+          <h3 style={{ display: "flex", alignItems: "center", gap: 6 }}>
+            <span style={{ flex: 1 }}>Filters</span>
+            <button
+              type="button"
+              onClick={() => setShowShortcutsHelp(true)}
+              title="Show keyboard shortcuts  (?)"
+              style={{
+                fontSize: 11,
+                padding: "0 6px",
+                border: "1px solid #bdc3c7",
+                background: "#fff",
+                color: "#34495e",
+                borderRadius: 10,
+                cursor: "pointer",
+                lineHeight: "16px",
+              }}
+            >
+              ? Shortcuts
+            </button>
+          </h3>
           <div className="filter-summary">
             Showing {filteredAssets.length} / {assets.length} loaded
             <button
@@ -4451,6 +4716,261 @@ function AppShell({
         </button>
       )}
 
+      {equalizeReport && (
+        <div
+          className="modal-backdrop"
+          onClick={() => setEqualizeReport(null)}
+        >
+          <div
+            className="modal-card"
+            onClick={(e) => e.stopPropagation()}
+            style={{ maxWidth: 560 }}
+          >
+            <button
+              className="modal-close"
+              onClick={() => setEqualizeReport(null)}
+            >
+              ✕
+            </button>
+            <h2>Spacing anomalies detected</h2>
+            <div className="status" style={{ marginBottom: 8 }}>
+              Median spacing along the road:{" "}
+              <strong>{equalizeReport.median_gap_m.toFixed(1)} m</strong> ·
+              arc length{" "}
+              <strong>{equalizeReport.arc_length_m.toFixed(0)} m</strong> ·
+              lateral offset{" "}
+              <strong>
+                {Math.abs(equalizeReport.lateral_offset_m).toFixed(1)} m{" "}
+                {equalizeReport.lateral_offset_m >= 0 ? "left" : "right"}
+              </strong>
+            </div>
+            <p style={{ fontSize: 12, color: "#444" }}>
+              {equalizeReport.anomalies.length} gap(s) are much larger than the
+              median — likely missed marker(s) in the original labelling. You
+              can still apply the equalization, but the known assets will be
+              spread evenly across the gap.
+            </p>
+            <div
+              style={{
+                maxHeight: 220,
+                overflowY: "auto",
+                border: "1px solid #ddd",
+                borderRadius: 4,
+                padding: 6,
+                fontSize: 12,
+              }}
+            >
+              <table style={{ width: "100%", borderCollapse: "collapse" }}>
+                <thead>
+                  <tr style={{ textAlign: "left", color: "#666" }}>
+                    <th style={{ padding: "2px 6px" }}>Between</th>
+                    <th style={{ padding: "2px 6px" }}>Gap</th>
+                    <th style={{ padding: "2px 6px" }}>Likely missing</th>
+                  </tr>
+                </thead>
+                <tbody>
+                  {equalizeReport.anomalies.map((g, i) => {
+                    const beforeRow = assets.find((a) => a.id === g.before_id);
+                    const afterRow = assets.find((a) => a.id === g.after_id);
+                    const label = (a: typeof beforeRow) =>
+                      a
+                        ? `${a.asset_name} · ${a.row_id.slice(-6)}`
+                        : "(unknown)";
+                    return (
+                      <tr
+                        key={`${g.before_id}-${g.after_id}-${i}`}
+                        style={{ borderTop: "1px dotted #eee" }}
+                      >
+                        <td style={{ padding: "3px 6px" }}>
+                          {label(beforeRow)} → {label(afterRow)}
+                        </td>
+                        <td
+                          style={{
+                            padding: "3px 6px",
+                            color: "#c0392b",
+                            fontWeight: 600,
+                          }}
+                        >
+                          {g.gap_m.toFixed(1)} m
+                        </td>
+                        <td style={{ padding: "3px 6px" }}>
+                          {g.expected_missing}
+                        </td>
+                      </tr>
+                    );
+                  })}
+                </tbody>
+              </table>
+            </div>
+            <div
+              style={{
+                display: "flex",
+                gap: 6,
+                marginTop: 12,
+                justifyContent: "flex-end",
+              }}
+            >
+              <button
+                className="primary-btn"
+                style={{ background: "#bdc3c7", color: "#222" }}
+                onClick={() => setEqualizeReport(null)}
+                disabled={busy}
+              >
+                Cancel
+              </button>
+              <button
+                className="primary-btn"
+                style={{ background: "#16a085" }}
+                onClick={async () => {
+                  const r = equalizeReport;
+                  setEqualizeReport(null);
+                  setBusy(true);
+                  try {
+                    await applyEqualization(r);
+                  } catch (e) {
+                    setStatus(`Apply failed: ${e}`);
+                    showToast(`Apply failed: ${e}`);
+                  } finally {
+                    setBusy(false);
+                  }
+                }}
+                disabled={busy}
+              >
+                Apply anyway ({equalizeReport.proposals.length})
+              </button>
+            </div>
+          </div>
+        </div>
+      )}
+
+      {showShortcutsHelp && (
+        <div
+          className="modal-backdrop"
+          onClick={() => setShowShortcutsHelp(false)}
+        >
+          <div
+            className="modal-card"
+            onClick={(e) => e.stopPropagation()}
+            style={{ maxWidth: 620 }}
+          >
+            <button
+              className="modal-close"
+              onClick={() => setShowShortcutsHelp(false)}
+            >
+              ✕
+            </button>
+            <h2>Keyboard shortcuts</h2>
+            <div className="status" style={{ marginBottom: 8 }}>
+              Press <kbd>?</kbd> anywhere to open this dialog. <kbd>?</kbd>{" "}
+              again or <kbd>Esc</kbd> closes it. Hover any button in the side
+              panels for tooltips.
+            </div>
+            {(
+              [
+                {
+                  group: "Selection & navigation",
+                  rows: [
+                    ["[", "Previous navigable asset"],
+                    ["]", "Next navigable asset"],
+                    ["Ctrl/⌘ + click", "Add asset to multi-select halo"],
+                    ["C", "Fit map to focused video / all data"],
+                    ["Esc", "Cancel current mode (lasso, link-pick, draw, OSM editing, magnifier, this dialog)"],
+                  ],
+                },
+                {
+                  group: "Asset actions",
+                  rows: [
+                    ["R", "Rename selected asset"],
+                    ["A", "Toggle anchor on selected asset (then drag → Distribute)"],
+                    ["Delete / Backspace", "Delete selected / multi-selected asset(s)"],
+                  ],
+                },
+                {
+                  group: "Image popup & bbox",
+                  rows: [
+                    ["H", "Toggle image popup (works while Ctrl-held)"],
+                    ["B", "Toggle bbox edit mode (popup must be on)"],
+                  ],
+                },
+                {
+                  group: "Lasso region",
+                  rows: [
+                    ["L", "Auto-link L↔R inside lasso"],
+                    ["Shift + L", "Auto-link by video inside lasso"],
+                    ["Alt + L", "Auto-link nearest inside lasso"],
+                    ["K", "Clear links on lasso selection"],
+                  ],
+                },
+                {
+                  group: "OSM edit mode",
+                  rows: [
+                    ["O", "Toggle OSM edit mode"],
+                    ["Delete / Backspace", "Delete marked vertices, then selected roads"],
+                    ["Shift + click on road", "Insert a vertex at click point"],
+                  ],
+                },
+                {
+                  group: "Other",
+                  rows: [
+                    ["?", "Show / hide this cheat-sheet"],
+                    ["Delete (with link selected)", "Unlink the selected pair"],
+                  ],
+                },
+              ] as Array<{ group: string; rows: Array<[string, string]> }>
+            ).map((sec) => (
+              <div key={sec.group} style={{ marginBottom: 10 }}>
+                <h4
+                  style={{
+                    margin: "8px 0 4px",
+                    fontSize: 11,
+                    textTransform: "uppercase",
+                    color: "#555",
+                    letterSpacing: 0.5,
+                  }}
+                >
+                  {sec.group}
+                </h4>
+                <table
+                  style={{
+                    width: "100%",
+                    fontSize: 12,
+                    borderCollapse: "collapse",
+                  }}
+                >
+                  <tbody>
+                    {sec.rows.map(([key, label]) => (
+                      <tr key={key + label}>
+                        <td
+                          style={{
+                            width: 180,
+                            padding: "3px 6px 3px 0",
+                            verticalAlign: "top",
+                          }}
+                        >
+                          <kbd
+                            style={{
+                              fontFamily: "monospace",
+                              background: "#ecf0f1",
+                              border: "1px solid #bdc3c7",
+                              borderRadius: 3,
+                              padding: "1px 6px",
+                              fontSize: 11,
+                            }}
+                          >
+                            {key}
+                          </kbd>
+                        </td>
+                        <td style={{ padding: "3px 0" }}>{label}</td>
+                      </tr>
+                    ))}
+                  </tbody>
+                </table>
+              </div>
+            ))}
+          </div>
+        </div>
+      )}
+
       {renameOpen && (
         <div
           className="modal-backdrop"
@@ -5910,6 +6430,22 @@ function AppShell({
                 Clear anchors
               </button>
             </div>
+            {anchors.size === 2 && lassoSelected && (
+              <button
+                className="primary-btn"
+                style={{
+                  marginTop: 4,
+                  width: "100%",
+                  background: "#16a085",
+                  fontSize: 11,
+                }}
+                onClick={handleEqualizeAlongRoad}
+                disabled={busy || lassoSelected.ids.length === 0}
+                title="Project the two anchors + lassoed assets onto the nearest OSM road and redistribute them at constant arc-length spacing. Runs a gap check first; if discrepancies are found you'll be prompted."
+              >
+                Equalize along road
+              </button>
+            )}
           </div>
         )}
         <button
@@ -6206,7 +6742,7 @@ function AppShell({
                   style={{ background: "#16a085", flex: 1, fontSize: 11 }}
                   onClick={() => handleAutoLink("side")}
                   disabled={busy}
-                  title="Auto-pair Left↔Right within this polygon by proximity"
+                  title="Auto-pair Left↔Right within this region by proximity  (L)"
                 >
                   Auto-link L↔R
                 </button>
@@ -6215,7 +6751,7 @@ function AppShell({
                   style={{ background: "#1abc9c", flex: 1, fontSize: 11 }}
                   onClick={() => handleAutoLink("video")}
                   disabled={busy}
-                  title="Auto-pair across the two videos in this polygon"
+                  title="Auto-pair across the two videos in this region  (Shift+L)"
                 >
                   Auto-link by video
                 </button>
@@ -6224,7 +6760,7 @@ function AppShell({
                   style={{ background: "#16a085", flex: 1, fontSize: 11 }}
                   onClick={() => handleAutoLink("none")}
                   disabled={busy}
-                  title="Pair nearest neighbours in the polygon, ignoring side and video. Use when video_name is missing."
+                  title="Pair nearest neighbours in the region, ignoring side and video. Use when video_name is missing.  (Alt+L)"
                 >
                   Auto-link nearest
                 </button>
@@ -6256,7 +6792,7 @@ function AppShell({
                   await refreshAfterMutation();
                 }}
                 disabled={busy || lassoSelected.ids.length === 0}
-                title="Remove auto-link / locked-link from every asset in the lasso"
+                title="Remove auto-link / locked-link from every asset in the lasso  (K)"
               >
                 Clear links
               </button>
@@ -6647,7 +7183,7 @@ function AppShell({
                     });
                   }}
                   disabled={busy}
-                  title="Mark this asset as a GPS-correction anchor. Drag it after marking, then press Distribute to propagate the offset to other visible assets."
+                  title="Mark this asset as a GPS-correction anchor. Drag it after marking, then press Distribute to propagate the offset to other visible assets.  (A)"
                 >
                   {isAnchor ? "★ Anchor (click to unmark)" : "Mark as anchor"}
                 </button>