Add EXIF writing and machine metadata support

README.md

@@ -117,6 +117,15 @@ python scraper.py --machine "BW3-20 [AMR-26]" --scan-id 158374 --workers 4
 | `--list-scans` | Print all scans for `--machine` and exit |
 | `--verbose` / `-v` | Debug logging |
 
+### `config.yaml` (optional keys)
+
+| Key | Description |
+|---|---|
+| `write_exif` | If true (default), write EXIF to each `mosaic.jpg` after download. Set to false to skip. |
+| `machine_metadata` | Map of machine label → optional fields for mosaic EXIF: `plot_number`, `enclosure` (bool), `temp_treatment` (number or string), `co2_treatment` (`ambient` / `elevated`), `latitude_wgs_84`, `longitude_wgs_84`, `elevation_masl`. Omitted keys are not written. |
+
+`config.example.yaml` lists all 12 machine labels with full `machine_metadata` (plot, enclosure, treatments, WGS84 coordinates, elevation) and an optional `machines` filter (commented).
+
 ---
 
 ## Output layout
@@ -131,7 +140,7 @@ archives/
     └── 2024-07-29/
         └── 158374/
             ├── metadata.json   # full scan parameters (grid, timestamps, etc.)
-            ├── mosaic.jpg      # pre-stitched full image (~16 MB)
+            ├── mosaic.jpg      # pre-stitched full image (~16 MB), EXIF after download
             └── tiles/
                 ├── tile_r000_c000.jpg   # row 0, column 0 (zero-padding matches grid size)
                 ├── tile_r000_c001.jpg
@@ -140,6 +149,8 @@ archives/
 
 Tile filenames encode position: `tile_r{row}_c{col}.jpg` where row increases with depth (Y in mm) and column increases along the tube circumference (X in mm).
 
+**Mosaic `mosaic.jpg` EXIF** (when `write_exif` is true in `config.yaml`, default on): set immediately after a successful download via `piexif` (no re-encoding). Includes `DateTime` / `DateTimeOriginal` (from scan time), `ImageDescription` (machine, scan id, name), `Make` = RootView, `Model` = machine label, `Software` = RootView + server version, `ProcessingSoftware` = this scraper, `Artist` (user), a one-line `UserComment` (grid size, pointer to `metadata.json`, and when set in `machine_metadata`: `plot_number`, `enclosure`, `temp_treatment`, `co2_treatment`), `XPKeywords` with the same treatment fields when any of those four are set, and GPS when `latitude_wgs_84`, `longitude_wgs_84`, and optionally `elevation_masl` are set. See `config.example.yaml` for the `machine_metadata` layout.
+
 ### Metadata files
 
 **`scans.csv`** columns: `machine`, `machine_id`, `scan_id`, `name`, `scan_time`, `start_x`, `start_y`, `end_x`, `end_y`, `dx`, `dy`, `nx`, `ny`, `total_tiles`, `scan_lines`, `scan_mode`, `start_datetime`, `end_datetime`, `status`, `user`, `disk_space_mb`, `mosaic_url`, `mosaic_local_path`, `mosaic_on_disk`
@@ -195,7 +206,7 @@ Every run prints a summary table on completion:
   Run complete
 ──────────────────────────────────────────────
   Machines:             1
-  Scans fetched:        428  (2 already cached, 0 failed)
+  Scans (metadata) fetched: 428  (2 already cached, 0 metadata failed)
   Metadata written:     428  (new JSON files)
 ──────────────────────────────────────────────
   Scans CSV:            archives/scans.csv
@@ -203,10 +214,11 @@ Every run prints a summary table on completion:
 ──────────────────────────────────────────────
 ```
 
-- **Scans fetched**: metadata detail page was retrieved from the server this run.
+- **Scans (metadata) fetched**: RootView scan detail page was retrieved (grid params, etc.). This does not mean the mosaic downloaded successfully; use **Mosaics downloaded** / **Mosaics failed** when not in `--metadata-only` mode.
 - **Already cached**: `metadata.json` already existed on disk; no HTTP request was made.
-- **Failed**: fetch error or scan missing required grid parameters.
+- **metadata failed**: metadata fetch error or scan missing required grid parameters.
 - **Metadata written**: new `metadata.json` files created (shown in `--metadata-only` mode).
+- **Mosaics failed** (when present): mosaic URL was requested but the file was not saved (e.g. HTTP 404, or empty body). Check the log for the exact URL.
 - Mosaic and tile counts appear in their respective modes.
 
 ---
@@ -219,3 +231,4 @@ Every run prints a summary table on completion:
 | `beautifulsoup4` + `lxml` | HTML parsing |
 | `pyyaml` | Config file |
 | `tqdm` | Progress bars |
+| `piexif` | EXIF for downloaded mosaics |