Thumb orientation + library filter on /photos/exif

Two follow-ups on the same feature branch:

1. Bake EXIF orientation into generated thumbnails. The `image` crate
   doesn't apply Orientation on load, and `save_with_format(..Jpeg)`
   drops EXIF — so portrait phone shots ended up sideways in any client
   that displays the cached thumb directly (no EXIF tag for the browser
   to compensate from). New `exif::read_orientation` reads the tag
   cheaply (no full EXIF parse) and `exif::apply_orientation` does the
   rotate/flip via image's existing `rotate90/180/270` + `fliph/flipv`.
   Applied in both branches of `generate_image_thumbnail` (RAW embedded-
   JPEG path and the regular `image::open` path). Existing thumbnails
   in the cache are still wrong-orientation; wipe the thumb dir or run
   a one-off backfill once this lands.

2. Optional `library` query param on `/photos/exif`. Accepts numeric id
   or name (same shape as `/image?library=...`), resolved via the
   existing `resolve_library_param` helper so a bad value 400s before
   we touch the DAO. Filter is applied post-query in the handler
   rather than pushed into `query_by_exif` to keep the DAO trait
   (and its test mocks) unchanged. Cheap enough at typical library
   counts; can be moved into SQL later if it ever isn't.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/data/mod.rs

@@ -418,6 +418,10 @@ pub struct ExifBatchRequest {
     pub date_from: Option<i64>,
     /// Upper bound (inclusive). Same semantics as `date_to` on `/photos`.
     pub date_to: Option<i64>,
+    /// Restrict results to a single library by id. Omit (or "" / "all") for
+    /// union mode — the default. Filtered post-query in the handler so the
+    /// existing `query_by_exif` DAO trait stays untouched.
+    pub library: Option<String>,
 }
 
 #[derive(Deserialize)]

src/exif.rs

@@ -4,6 +4,7 @@ use std::path::Path;
 
 use anyhow::{Result, anyhow};
 use exif::{In, Reader, Tag, Value};
+use image::DynamicImage;
 use log::debug;
 use serde::{Deserialize, Serialize};
 
@@ -177,6 +178,37 @@ pub fn extract_exif_from_path(path: &Path) -> Result<ExifData> {
     Ok(data)
 }
 
+/// Read just the EXIF Orientation tag (1..=8) from a file. Cheaper than a
+/// full `extract_exif_from_path` when the caller only needs orientation —
+/// e.g. the thumbnail pipeline, which has to bake the rotation into the
+/// resized pixels because the saved thumb has no EXIF chunk for the browser
+/// to apply.
+pub fn read_orientation(path: &Path) -> Option<i32> {
+    let file = File::open(path).ok()?;
+    let mut reader = BufReader::new(file);
+    let exif = Reader::new().read_from_container(&mut reader).ok()?;
+    let field = exif.get_field(Tag::Orientation, In::PRIMARY)?;
+    get_u32_value(field).map(|v| v as i32)
+}
+
+/// Apply an EXIF Orientation (1..=8) to a `DynamicImage`, returning a
+/// canonically-oriented copy. Orientations:
+///   1 → as-is, 2 → flipH, 3 → rot180, 4 → flipV,
+///   5 → rot90CW + flipH, 6 → rot90CW, 7 → rot270CW + flipH, 8 → rot270CW.
+/// Anything else (missing tag, garbage values) is returned unchanged.
+pub fn apply_orientation(img: DynamicImage, orientation: i32) -> DynamicImage {
+    match orientation {
+        2 => img.fliph(),
+        3 => img.rotate180(),
+        4 => img.flipv(),
+        5 => img.rotate90().fliph(),
+        6 => img.rotate90(),
+        7 => img.rotate270().fliph(),
+        8 => img.rotate270(),
+        _ => img,
+    }
+}
+
 fn get_string_value(field: &exif::Field) -> Option<String> {
     match &field.value {
         Value::Ascii(vec) => {

src/files.rs

@@ -1217,6 +1217,21 @@ pub async fn list_exif_summary(
         "date_to",
         req.date_to.map(|v| v.to_string()).unwrap_or_default(),
     ));
+    span.set_attribute(KeyValue::new(
+        "library",
+        req.library.clone().unwrap_or_default(),
+    ));
+
+    // Resolve the library filter up front so a bad id/name 400s before we
+    // ever take the DAO mutex. None == union across all libraries.
+    let library_filter =
+        match crate::libraries::resolve_library_param(&app_state, req.library.as_deref()) {
+            Ok(lib) => lib.map(|l| l.id),
+            Err(msg) => {
+                span.set_status(Status::error(msg.clone()));
+                return Ok(HttpResponse::BadRequest().json(serde_json::json!({ "error": msg })));
+            }
+        };
     let cx = opentelemetry::Context::current_with_span(span);
 
     // Pre-build an id → name map so we don't linear-scan libraries per row.
@@ -1231,6 +1246,11 @@ pub async fn list_exif_summary(
         Ok(rows) => {
             let photos: Vec<ExifSummary> = rows
                 .into_iter()
+                // Library filter post-query: keeps the DAO trait (and its
+                // mocks) unchanged. For typical 2–3 library setups the in-
+                // memory pass over a date-bounded result set is negligible;
+                // can be pushed into SQL later if it ever isn't.
+                .filter(|r| library_filter.is_none_or(|id| r.library_id == id))
                 .map(|r| ExifSummary {
                     library_name: library_names.get(&r.library_id).cloned(),
                     file_path: r.file_path,

src/main.rs

@@ -1071,6 +1071,13 @@ pub fn unsupported_thumbnail_sentinel(thumb_path: &Path) -> PathBuf {
 }
 
 fn generate_image_thumbnail(src: &Path, thumb_path: &Path) -> std::io::Result<()> {
+    // The `image` crate doesn't auto-apply EXIF Orientation on load, and
+    // saving back out as JPEG drops EXIF entirely — so without baking the
+    // rotation into the pixels here, browsers see the raw landscape buffer
+    // of a portrait phone shot and render it sideways. Read once up front
+    // and apply to whichever decode branch we end up taking.
+    let orientation = exif::read_orientation(src).unwrap_or(1);
+
     // RAW formats (ARW/NEF/CR2/etc): try the file's embedded JPEG preview
     // first. Avoids ffmpeg choking on proprietary RAW compression (Sony ARW
     // in particular), and is faster than decoding RAW pixels anyway.
@@ -1081,6 +1088,7 @@ fn generate_image_thumbnail(src: &Path, thumb_path: &Path) -> std::io::Result<()
                 format!("decode embedded preview {:?}: {}", src, e),
             )
         })?;
+        let img = exif::apply_orientation(img, orientation);
         let scaled = img.thumbnail(200, u32::MAX);
         scaled
             .save_with_format(thumb_path, image::ImageFormat::Jpeg)
@@ -1095,6 +1103,7 @@ fn generate_image_thumbnail(src: &Path, thumb_path: &Path) -> std::io::Result<()
     let img = image::open(src).map_err(|e| {
         std::io::Error::new(std::io::ErrorKind::InvalidData, format!("{:?}: {}", src, e))
     })?;
+    let img = exif::apply_orientation(img, orientation);
     let scaled = img.thumbnail(200, u32::MAX);
     scaled
         .save(thumb_path)