feat(photos): read the EXIF of an uploaded photo

Closes the third source of capture metadata (#1614). Provider photos are asked
for, uploaded files carry their own answer — and until now nobody read it, so
the most common case of all, a photo taken on the trip and uploaded straight
into the journey, could never appear on the map.

exifr rather than a heavier image library: pure JS, no native build, so no
musl-pin dance in the Alpine image. Only four tags are picked, so a large file
is not fully parsed. The resolved path is checked against the uploads root
before it is opened.

One thing worth knowing before someone files a bug about it: the client
converts HEIC before upload and that conversion drops GPS, so an iPhone photo
arrives here already stripped. Nothing to read is the expected outcome more
often than not, which is why the empty case is silent.

server/src/nest/journey/journey.controller.ts

@@ -212,6 +212,7 @@ export class JourneyController {
     if (!results.length) {
       throw new HttpException({ error: 'Not allowed' }, 403);
     }
+    this.backfillCapture(results, user.id);
     return { photos: results };
   }
 
@@ -293,6 +294,9 @@ export class JourneyController {
     if (!photos.length) {
       throw new HttpException({ error: 'Not allowed' }, 403);
     }
+    // An uploaded file carries its own EXIF; reading it is what puts the photo on
+    // the map later. Detached, like the provider branch.
+    this.backfillCapture(photos, user.id);
     return { photos };
   }
 

server/src/nest/memories/photo-capture-backfill.service.ts

@@ -1,4 +1,7 @@
 import { Injectable } from '@nestjs/common';
+import path from 'node:path';
+import exifr from 'exifr';
+import { UPLOADS_ROOT } from './uploads-root';
 import { PhotoResolverService } from './photo-resolver.service';
 import { TrekPhotosRepository } from '../photos/trek-photos.repository';
 
@@ -37,6 +40,14 @@ export class PhotoCaptureBackfillService {
         // per photo is the expensive part of an album import.
         if (!photo || (photo.taken_at && photo.lat != null && photo.lng != null)) continue;
 
+        // A local file has no provider to ask — the answer is in its own EXIF, and
+        // getPhotoInfo would only hand back what the DB row already says.
+        if (photo.provider === 'local') {
+          const meta = await this.readLocalExif(photo.file_path);
+          if (meta) this.photos.recordCaptureMetadata(id, meta);
+          continue;
+        }
+
         const info = await this.resolver.getPhotoInfo(id, userId);
         if (!info.success) continue;
 
@@ -50,4 +61,33 @@ export class PhotoCaptureBackfillService {
       }
     }
   }
+
+  /**
+   * EXIF of an uploaded file.
+   *
+   * Note for anyone chasing "my phone photo has no location": the client converts
+   * HEIC before upload and that conversion drops GPS, so an iPhone photo arrives
+   * here already stripped. Nothing to read is the expected outcome far more often
+   * than not — hence no logging on the empty case.
+   */
+  private async readLocalExif(
+    filePath?: string | null,
+  ): Promise<{ takenAt: string | null; lat: number | null; lng: number | null } | null> {
+    if (!filePath) return null;
+    // Never let a stored path climb out of the uploads tree.
+    const abs = path.resolve(UPLOADS_ROOT, filePath);
+    if (abs !== UPLOADS_ROOT && !abs.startsWith(UPLOADS_ROOT + path.sep)) return null;
+
+    const parsed = await exifr.parse(abs, { pick: ['DateTimeOriginal', 'CreateDate', 'latitude', 'longitude'] })
+      .catch(() => null) as
+      | { DateTimeOriginal?: Date; CreateDate?: Date; latitude?: number; longitude?: number }
+      | null;
+    if (!parsed) return null;
+
+    const taken = parsed.DateTimeOriginal ?? parsed.CreateDate ?? null;
+    const takenAt = taken instanceof Date && !Number.isNaN(taken.getTime()) ? taken.toISOString() : null;
+    const lat = typeof parsed.latitude === 'number' ? parsed.latitude : null;
+    const lng = typeof parsed.longitude === 'number' ? parsed.longitude : null;
+    return takenAt || lat != null ? { takenAt, lat, lng } : null;
+  }
 }