diff --git a/client/dive-common/use/useModeManager.spec.ts b/client/dive-common/use/useModeManager.spec.ts
index 9dd0e5cf1..d992430e3 100644
--- a/client/dive-common/use/useModeManager.spec.ts
+++ b/client/dive-common/use/useModeManager.spec.ts
@@ -15,7 +15,8 @@ import type { AnnotationId } from 'vue-media-annotator/BaseAnnotation';
 import type { MarkChangesPending } from 'vue-media-annotator/BaseAnnotationStore';
 import Track from 'vue-media-annotator/track';
 import { ROTATION_ATTRIBUTE_NAME } from 'vue-media-annotator/utils';
-import useModeManager from './useModeManager';
+import { clientSettings } from 'dive-common/store/settings';
+import useModeManager, { type StereoAnnotationCompleteParams } from './useModeManager';
 import HeadTail from '../recipes/headtail';
 import { headTailFeatures } from '../../src/headTail';
 import type Recipe from '../../src/recipe';
@@ -24,7 +25,11 @@ function translation(tx: number, ty: number): Matrix3 {
   return [[1, 0, tx], [0, 1, ty], [0, 0, 1]];
 }
 
-function makeHarness(markChangesPending: MarkChangesPending = () => undefined, recipes: Recipe[] = []) {
+function makeHarness(
+  markChangesPending: MarkChangesPending = () => undefined,
+  recipes: Recipe[] = [],
+  onStereoAnnotationComplete: ((params: StereoAnnotationCompleteParams) => void) | undefined = undefined,
+) {
   const cameraStore = new CameraStore({ markChangesPending });
   cameraStore.removeCamera('singleCam');
   cameraStore.addCamera('left');
@@ -77,6 +82,7 @@ function makeHarness(markChangesPending: MarkChangesPending = () => undefined, r
     readonlyState: ref(false),
     recipes,
     alignedView,
+    onStereoAnnotationComplete,
   });
   modeManager.selectedCamera.value = 'left';
   return {
@@ -457,6 +463,29 @@ describe('centerline editing continuity', () => {
   });
 });
 
+describe('stereo mapping of a line being drawn', () => {
+  it('waits for both ends instead of mapping the first one alone', () => {
+    const wasAutoCompute = clientSettings.stereoSettings.autoComputeOtherCamera;
+    clientSettings.stereoSettings.autoComputeOtherCamera = true;
+    try {
+      const recipe = new HeadTail();
+      const events: StereoAnnotationCompleteParams[] = [];
+      const { modeManager: manager } = makeHarness(undefined, [recipe], (params) => events.push(params));
+      manager.handler.trackAdd();
+      recipe.activate();
+      const draw = (coordinates: number[][]) => manager.handler.updateGeoJSON('in-progress', 0, 0, {
+        type: 'Feature', properties: {}, geometry: { type: 'LineString', coordinates },
+      }, 'HeadTails');
+      draw([[10, 10]]);
+      expect(events).toEqual([]);
+      draw([[10, 10], [90, 10]]);
+      expect(events.map((e) => e.type)).toEqual(['line']);
+    } finally {
+      clientSettings.stereoSettings.autoComputeOtherCamera = wasAutoCompute;
+    }
+  });
+});
+
 describe('entering polygon editing', () => {
   const polygon = (key: string): GeoJSON.Feature<GeoJSON.Polygon> => ({
     type: 'Feature',
diff --git a/client/dive-common/use/useModeManager.ts b/client/dive-common/use/useModeManager.ts
index 4568fbbd8..472ee80ec 100644
--- a/client/dive-common/use/useModeManager.ts
+++ b/client/dive-common/use/useModeManager.ts
@@ -972,9 +972,11 @@ export default function useModeManager({
 
           mirrorFeatureToAlignedCameras(track.id, frameNum);
 
-          // Emit persisted named points, including a head placed before its tail.
-          // Completed lines use their existing whole-line transfer event instead.
+          // Emit persisted named points. Completed lines use their existing
+          // whole-line transfer event instead, and the first end of a line still
+          // being drawn waits for it: mapping it mid-draw interrupts the draw.
           if (onStereoAnnotationComplete && stereoInteractiveActive()
+              && update.done.every((v) => v !== false)
               && !(data.geometry.type === 'LineString' && data.geometry.coordinates.length >= 2)) {
             Object.entries(update.geoJsonFeatureRecord).forEach(([pointKey, geoms]) => {
               geoms.forEach((geom) => {
diff --git a/client/platform/desktop/frontend/components/ViewerLoader.vue b/client/platform/desktop/frontend/components/ViewerLoader.vue
index 88a81f97b..a77e12e4a 100644
--- a/client/platform/desktop/frontend/components/ViewerLoader.vue
+++ b/client/platform/desktop/frontend/components/ViewerLoader.vue
@@ -1164,6 +1164,7 @@ export default defineComponent({
     // line at this frame. Once set, interactive stereo never overwrites that
     // side's geometry again — only the user can. Kept off the Attributes panel.
     const STEREO_USER_LINE_ATTR = 'stereo_user_line';
+    const STEREO_LOADING_DIALOG_DELAY_MS = 300;
     // How the length was set: 'stereo' = auto-computed from the warped lines,
     // 'user_set' = locked by the user (auto-update leaves the length alone).
     const STEREO_LENGTH_METHOD_ATTR = 'length_method';
@@ -1632,10 +1633,15 @@ export default defineComponent({
 
       // Show loading indicator while waiting for stereo transfer (interactive
       // single-transfer path only; bulk import owns the dialog itself).
-      if (!quiet) {
-        stereoLoadingMessage.value = 'Computing stereo correspondence...';
-        stereoLoadingError.value = '';
-        stereoLoadingDialog.value = true;
+      // Only once the wait is noticeable, so a fast transfer doesn't flash it,
+      // and never for a single point.
+      let loadingTimer: number | undefined;
+      if (!quiet && params.type !== 'point') {
+        loadingTimer = window.setTimeout(() => {
+          stereoLoadingMessage.value = 'Computing stereo correspondence...';
+          stereoLoadingError.value = '';
+          stereoLoadingDialog.value = true;
+        }, STEREO_LOADING_DIALOG_DELAY_MS);
       }
 
       const pointTargetBefore = params.type === 'point'
@@ -1916,10 +1922,6 @@ export default defineComponent({
             }
           }
         }
-        // Success — hide loading dialog (interactive path only)
-        if (!quiet) {
-          stereoLoadingDialog.value = false;
-        }
         return 'transferred';
       } catch (err) {
         const message = err instanceof Error ? err.message : String(err);
@@ -1936,6 +1938,9 @@ export default defineComponent({
         stereoLoadingError.value = `Failed to transfer annotation to the other camera. ${message}`;
         stereoLoadingDialog.value = true;
         return 'failed';
+      } finally {
+        window.clearTimeout(loadingTimer);
+        if (!quiet && !stereoLoadingError.value) stereoLoadingDialog.value = false;
       }
     }