um0 add per-camera filter pages

Implement render_camera_pages <html_dir> <backhref> in stats.source.sh: one
camera-<slug>.html per camera in STATS_CAMERA_SLUGS, reusing the aggregation's
collision-resolved slugs and per-camera photo lists so filenames match pm0's
leaderboard links. Each page reuses the shared header/footer chrome plus a new
camera.tmpl that renders an HTML-escaped camera heading, a pre-built thumbnail
grid, and a back-to-stats link.

Thumbnails reuse preview.tmpl's markup style (thumb image from thumbs/) but link
to the full-size image under photos/ rather than a per-photo view page, since the
view-page name is not derivable outside the album pagination loop. The photos and
thumbs dir names are fixed to match generate()'s render_album_pages call.

Cameras are walked in LC_ALL=C label order for reproducible output, and cameras
with no recorded photos are skipped. Adds the camera_name/camera_thumbs render
field specs and a tests/cli.sh case covering per-camera files, slug collisions,
HTML escaping, thumbnail link targets, and determinism.

This provides the function + template + tests only; wiring into generate() and
the STATS_PAGE toggle remain for rm0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

5 files changed, 381 insertions, 2 deletions

diff --git a/bin/shuriken b/bin/shuriken
index 63e0a7f..ec8e52b 100755
--- a/bin/shuriken
+++ b/bin/shuriken
@@ -606,9 +606,11 @@ current_date_text_to() {
 declare -ra TEMPLATE_RENDER_FIELD_SPECS=(
     'render_animation_class_html|context_html|animation_class|animation_class|preview details view'
     'render_backhref_css|context_css|backhref|backhref|header splash'
-    'render_backhref_html|context_html|backhref|backhref|footer header preview splash details view stats'
+    'render_backhref_html|context_html|backhref|backhref|footer header preview splash details view stats camera'
     'render_background_image_css|context_css|background_image|background_image|header splash'
     'render_blurs_dir_css|context_css|blurs_dir|blurs_dir|header splash'
+    'render_camera_name_html|context_html|camera_name|camera_name|camera'
+    'render_camera_thumbs_html|context_raw|camera_thumbs|camera_thumbs|camera'
     'render_current_date_text|current_date_html|||'
     'render_enter_page_html|context_html|enter_page|enter_page|splash'
     'render_exif_details_html|context_raw|exif_details|exif_details|details'
@@ -3577,6 +3579,129 @@ render_stats_page() {
         tarball_name ''
 }
 
+# ----------------------------------------------------------------------------
+# Per-camera filter pages (task um0)
+# ----------------------------------------------------------------------------
+# render_camera_pages turns the per-camera photo lists collected by the
+# aggregation into one camera-<slug>.html page each, reusing the slugs the
+# aggregation already stored in STATS_CAMERA_SLUGS/STATS_CAMERA_PHOTOS so the
+# filenames match the camera-<slug>.html links pm0's leaderboard emits. Like the
+# stats page, the variable-length markup (the thumbnail grid) is built here as a
+# raw HTML string and handed to camera.tmpl through the camera_thumbs context
+# field; camera.tmpl supplies only the page chrome (heading + back-to-stats
+# link), wrapped by the shared header/footer the same way render_stats_page does.
+#
+# The album's incoming photo and thumbnail directories are the conventional
+# 'photos'/'thumbs' that generate() passes to render_album_pages
+# (render_album_pages 'photos' '.' 'thumbs' ...), so the grid reuses preview.tmpl's
+# thumbnail markup style with those fixed dir names. Each thumbnail links to the
+# full-size image under photos/ (backhref/photos/<file>) rather than a per-photo
+# <page>-<preview>.html view page: a camera page is rendered outside the album
+# pagination loop and cannot know which view page a given photo landed on, so the
+# original image under photos/ is the only target derivable in this context (this
+# choice is also documented in camera.tmpl).
+
+# Dist-relative subdirectories that hold the full-size images and thumbnails.
+# These mirror the literals generate() passes to render_album_pages so camera
+# pages link to the same assets the album pages do.
+declare -gr STATS_CAMERA_PHOTOS_DIR='photos'
+declare -gr STATS_CAMERA_THUMBS_DIR='thumbs'
+
+# Emit one thumbnail anchor for the camera grid: a thumb image (from thumbs/)
+# wrapped in a link to the full-size image (from photos/), both resolved through
+# the page's backhref. The photo filename is HTML-escaped because it ends up in
+# both href and src attributes. Mirrors preview.tmpl's markup but targets the
+# full image instead of a view page (see render_camera_pages header comment).
+_stats_camera_thumbnail() {
+    local -r backhref_html="$1"; shift
+    local -r photo="$1"; shift
+    local photo_html
+
+    photo_html=$(_html_escape "$photo")
+    printf '        <a href="%s/%s/%s">' \
+        "$backhref_html" "$STATS_CAMERA_PHOTOS_DIR" "$photo_html"
+    printf '<img class="thumb" src="%s/%s/%s" /></a>\n' \
+        "$backhref_html" "$STATS_CAMERA_THUMBS_DIR" "$photo_html"
+}
+
+# Build the full thumbnail grid for one camera from its newline-separated photo
+# list. Photos keep aggregation order (the order they were encountered) so the
+# grid is deterministic for a given input. Returns the grid HTML on stdout.
+_stats_build_camera_thumbs() {
+    local -r backhref_html="$1"; shift
+    local -r photos="$1"; shift
+    local photo
+
+    while IFS= read -r photo; do
+        if [ -n "$photo" ]; then
+            _stats_camera_thumbnail "$backhref_html" "$photo"
+        fi
+    done <<< "$photos"
+}
+
+# Render a single camera-<slug>.html: header + camera.tmpl (escaped heading and
+# pre-built thumbnail grid) + footer. The label is HTML-escaped via camera.tmpl's
+# context_html field spec; backhref_html is the already-escaped path used inside
+# the grid anchors so thumbnail links resolve from the page's location.
+_stats_render_camera_page() {
+    local -r html_dir="$1"; shift
+    local -r backhref="$1"; shift
+    local -r label="$1"; shift
+    local -r slug="$1"; shift
+    local -r photos="$1"; shift
+    local backhref_html
+    local camera_thumbs
+    local -r page="camera-$slug.html"
+
+    backhref_html=$(_html_escape "$backhref")
+    camera_thumbs=$(_stats_build_camera_thumbs "$backhref_html" "$photos")
+    template header "$page" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        blurs_dir '' \
+        background_image '' \
+        show_header_bar 'yes'
+    template camera "$page" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        camera_name "$label" \
+        camera_thumbs "$camera_thumbs"
+    template footer "$page" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        tarball_name ''
+}
+
+# Public render entry point (handoff for task rm0). Renders one
+# camera-<slug>.html per camera in STATS_CAMERA_SLUGS, each showing a thumbnail
+# grid of that camera's photos and a link back to the stats page. Call
+# collect_photo_exif_stats first to fill the globals.
+#   render_camera_pages <html_dir> <backhref>
+# html_dir is the dist-relative output directory (top-level album: "."), backhref
+# is the relative path back to the album root ("." for a top-level album), the
+# same values rm0 passes to render_stats_page. Cameras are walked in LC_ALL=C
+# label order (matching pm0's reproducible-output convention) and cameras with no
+# recorded photos are skipped.
+render_camera_pages() {
+    local -r html_dir="$1"; shift
+    local -r backhref="$1"; shift
+    local label
+    local slug
+
+    if (( ${#STATS_CAMERA_SLUGS[@]} == 0 )); then
+        return
+    fi
+    while IFS= read -r label; do
+        slug="${STATS_CAMERA_SLUGS[$label]}"
+        if [ -z "${STATS_CAMERA_PHOTOS[$slug]:-}" ]; then
+            continue
+        fi
+        _stats_render_camera_page \
+            "$html_dir" "$backhref" "$label" "$slug" \
+            "${STATS_CAMERA_PHOTOS[$slug]}"
+    done < <(printf '%s\n' "${!STATS_CAMERA_SLUGS[@]}" | LC_ALL=C sort)
+}
+
 # Inlined from src/lib/config.source.sh
 existing_parent_dir() {
     local -r path="$1"; shift
diff --git a/share/templates/default/camera.tmpl b/share/templates/default/camera.tmpl
new file mode 100644
index 0000000..39ca273
--- /dev/null
+++ b/share/templates/default/camera.tmpl
@@ -0,0 +1,24 @@
+# Per-camera filter page body (task um0). Like stats.tmpl, all the variable-length
+# markup -- here the thumbnail grid of every photo shot with this camera -- is
+# pre-rendered by render_camera_pages in src/lib/stats.source.sh and handed in
+# through the raw context field render_camera_thumbs_html, so this template only
+# supplies the page chrome: the heading (the HTML-escaped camera name), the
+# pre-built grid, and a link back to the stats page. The surrounding
+# <html>/<head>/<body> and footer come from the header/footer templates, which
+# render_camera_pages emits around this one (same pattern as stats/view/details).
+#
+# Thumbnails link to the full-size image under photos/ rather than to a per-photo
+# view page: a camera page is built outside the album's pagination loop and so
+# cannot know which <page>-<preview>.html a given photo landed on. Linking to the
+# original image is the sensible derivable target (see render_camera_pages).
+cat <<END
+<div class="view stats camera">
+    <h1 class="stats-title">${render_title_html} &mdash; ${render_camera_name_html}</h1>
+    <div class="stats-back navigator">
+        <a href="${render_backhref_html}/stats.html">Back to stats</a>
+    </div>
+    <div class="camera-thumbs">
+${render_camera_thumbs_html}
+    </div>
+</div>
+END
diff --git a/src/lib/stats.source.sh b/src/lib/stats.source.sh
index 72b2d26..b0a1646 100644
--- a/src/lib/stats.source.sh
+++ b/src/lib/stats.source.sh
@@ -846,3 +846,126 @@ render_stats_page() {
         backhref "$backhref" \
         tarball_name ''
 }
+
+# ----------------------------------------------------------------------------
+# Per-camera filter pages (task um0)
+# ----------------------------------------------------------------------------
+# render_camera_pages turns the per-camera photo lists collected by the
+# aggregation into one camera-<slug>.html page each, reusing the slugs the
+# aggregation already stored in STATS_CAMERA_SLUGS/STATS_CAMERA_PHOTOS so the
+# filenames match the camera-<slug>.html links pm0's leaderboard emits. Like the
+# stats page, the variable-length markup (the thumbnail grid) is built here as a
+# raw HTML string and handed to camera.tmpl through the camera_thumbs context
+# field; camera.tmpl supplies only the page chrome (heading + back-to-stats
+# link), wrapped by the shared header/footer the same way render_stats_page does.
+#
+# The album's incoming photo and thumbnail directories are the conventional
+# 'photos'/'thumbs' that generate() passes to render_album_pages
+# (render_album_pages 'photos' '.' 'thumbs' ...), so the grid reuses preview.tmpl's
+# thumbnail markup style with those fixed dir names. Each thumbnail links to the
+# full-size image under photos/ (backhref/photos/<file>) rather than a per-photo
+# <page>-<preview>.html view page: a camera page is rendered outside the album
+# pagination loop and cannot know which view page a given photo landed on, so the
+# original image under photos/ is the only target derivable in this context (this
+# choice is also documented in camera.tmpl).
+
+# Dist-relative subdirectories that hold the full-size images and thumbnails.
+# These mirror the literals generate() passes to render_album_pages so camera
+# pages link to the same assets the album pages do.
+declare -gr STATS_CAMERA_PHOTOS_DIR='photos'
+declare -gr STATS_CAMERA_THUMBS_DIR='thumbs'
+
+# Emit one thumbnail anchor for the camera grid: a thumb image (from thumbs/)
+# wrapped in a link to the full-size image (from photos/), both resolved through
+# the page's backhref. The photo filename is HTML-escaped because it ends up in
+# both href and src attributes. Mirrors preview.tmpl's markup but targets the
+# full image instead of a view page (see render_camera_pages header comment).
+_stats_camera_thumbnail() {
+    local -r backhref_html="$1"; shift
+    local -r photo="$1"; shift
+    local photo_html
+
+    photo_html=$(_html_escape "$photo")
+    printf '        <a href="%s/%s/%s">' \
+        "$backhref_html" "$STATS_CAMERA_PHOTOS_DIR" "$photo_html"
+    printf '<img class="thumb" src="%s/%s/%s" /></a>\n' \
+        "$backhref_html" "$STATS_CAMERA_THUMBS_DIR" "$photo_html"
+}
+
+# Build the full thumbnail grid for one camera from its newline-separated photo
+# list. Photos keep aggregation order (the order they were encountered) so the
+# grid is deterministic for a given input. Returns the grid HTML on stdout.
+_stats_build_camera_thumbs() {
+    local -r backhref_html="$1"; shift
+    local -r photos="$1"; shift
+    local photo
+
+    while IFS= read -r photo; do
+        if [ -n "$photo" ]; then
+            _stats_camera_thumbnail "$backhref_html" "$photo"
+        fi
+    done <<< "$photos"
+}
+
+# Render a single camera-<slug>.html: header + camera.tmpl (escaped heading and
+# pre-built thumbnail grid) + footer. The label is HTML-escaped via camera.tmpl's
+# context_html field spec; backhref_html is the already-escaped path used inside
+# the grid anchors so thumbnail links resolve from the page's location.
+_stats_render_camera_page() {
+    local -r html_dir="$1"; shift
+    local -r backhref="$1"; shift
+    local -r label="$1"; shift
+    local -r slug="$1"; shift
+    local -r photos="$1"; shift
+    local backhref_html
+    local camera_thumbs
+    local -r page="camera-$slug.html"
+
+    backhref_html=$(_html_escape "$backhref")
+    camera_thumbs=$(_stats_build_camera_thumbs "$backhref_html" "$photos")
+    template header "$page" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        blurs_dir '' \
+        background_image '' \
+        show_header_bar 'yes'
+    template camera "$page" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        camera_name "$label" \
+        camera_thumbs "$camera_thumbs"
+    template footer "$page" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        tarball_name ''
+}
+
+# Public render entry point (handoff for task rm0). Renders one
+# camera-<slug>.html per camera in STATS_CAMERA_SLUGS, each showing a thumbnail
+# grid of that camera's photos and a link back to the stats page. Call
+# collect_photo_exif_stats first to fill the globals.
+#   render_camera_pages <html_dir> <backhref>
+# html_dir is the dist-relative output directory (top-level album: "."), backhref
+# is the relative path back to the album root ("." for a top-level album), the
+# same values rm0 passes to render_stats_page. Cameras are walked in LC_ALL=C
+# label order (matching pm0's reproducible-output convention) and cameras with no
+# recorded photos are skipped.
+render_camera_pages() {
+    local -r html_dir="$1"; shift
+    local -r backhref="$1"; shift
+    local label
+    local slug
+
+    if (( ${#STATS_CAMERA_SLUGS[@]} == 0 )); then
+        return
+    fi
+    while IFS= read -r label; do
+        slug="${STATS_CAMERA_SLUGS[$label]}"
+        if [ -z "${STATS_CAMERA_PHOTOS[$slug]:-}" ]; then
+            continue
+        fi
+        _stats_render_camera_page \
+            "$html_dir" "$backhref" "$label" "$slug" \
+            "${STATS_CAMERA_PHOTOS[$slug]}"
+    done < <(printf '%s\n' "${!STATS_CAMERA_SLUGS[@]}" | LC_ALL=C sort)
+}
diff --git a/src/lib/template.source.sh b/src/lib/template.source.sh
index 6d48ae5..9fd3ad4 100644
--- a/src/lib/template.source.sh
+++ b/src/lib/template.source.sh
@@ -144,9 +144,11 @@ current_date_text_to() {
 declare -ra TEMPLATE_RENDER_FIELD_SPECS=(
     'render_animation_class_html|context_html|animation_class|animation_class|preview details view'
     'render_backhref_css|context_css|backhref|backhref|header splash'
-    'render_backhref_html|context_html|backhref|backhref|footer header preview splash details view stats'
+    'render_backhref_html|context_html|backhref|backhref|footer header preview splash details view stats camera'
     'render_background_image_css|context_css|background_image|background_image|header splash'
     'render_blurs_dir_css|context_css|blurs_dir|blurs_dir|header splash'
+    'render_camera_name_html|context_html|camera_name|camera_name|camera'
+    'render_camera_thumbs_html|context_raw|camera_thumbs|camera_thumbs|camera'
     'render_current_date_text|current_date_html|||'
     'render_enter_page_html|context_html|enter_page|enter_page|splash'
     'render_exif_details_html|context_raw|exif_details|exif_details|details'
diff --git a/tests/cli.sh b/tests/cli.sh
index 48efc17..50a61f3 100755
--- a/tests/cli.sh
+++ b/tests/cli.sh
@@ -3821,6 +3821,108 @@ BASH
     test::teardown
 }
 
+test_render_camera_pages_renders_one_page_per_camera() {
+    local html
+    local html_again
+    local dist_dir
+
+    test::setup
+    dist_dir="$TEST_TMPDIR/dist"
+    mkdir -p "$dist_dir"
+
+    # Feed synthetic EXIF straight into accumulate_photo_stats (same approach as
+    # the stats-page test) to exercise three cameras: one whose label needs
+    # HTML-escaping (& and <), and a slug-collision pair ("Canon EOS 5D" vs
+    # "Canon EOS-5D" both slug to canon-eos-5d, so the second gets -2). Then
+    # render the per-camera pages twice into separate dirs to assert determinism.
+    bash -euo pipefail -s \
+        "$TEST_SHURIKEN" \
+        "$TEST_REPO_ROOT/share/templates/default" \
+        "$dist_dir" \
+        <<'BASH'
+shuriken="$1"; shift
+template_dir="$1"; shift
+dist_dir="$1"; shift
+
+# shellcheck source=/dev/null
+source <(sed '$d' "$shuriken")
+
+DIST_DIR="$dist_dir"
+TEMPLATE_DIR="$template_dir"
+TITLE='Stats album'
+HEIGHT=600
+THUMBHEIGHT=120
+MAXPREVIEWS=40
+ORIGINAL_BASEPATH=''
+TARBALL_INCLUDE=no
+SHURIKEN_OUTPUT_MODE=quiet
+apply_config_defaults
+
+feed() {
+    reset_photo_exif_stats
+    accumulate_photo_stats 'a.jpg' <<'EXIF'
+  Geometry: 6000x4000+0+0
+  exif:Make: Canon
+  exif:Model: Canon EOS 5D
+EXIF
+    accumulate_photo_stats 'b.jpg' <<'EXIF'
+  Geometry: 6000x4000+0+0
+  exif:Make: Canon
+  exif:Model: Canon EOS 5D
+EXIF
+    accumulate_photo_stats 'c.png' <<'EXIF'
+  Geometry: 4000x6000+0+0
+  exif:Make: Nikon & Co
+  exif:Model: <Z6>
+EXIF
+    accumulate_photo_stats 'd.jpg' <<'EXIF'
+  Geometry: 6000x4000+0+0
+  exif:Make: Canon
+  exif:Model: Canon EOS-5D
+EXIF
+}
+
+mkdir -p "$dist_dir/run1" "$dist_dir/run2"
+feed
+render_camera_pages run1 ..
+feed
+render_camera_pages run2 ..
+BASH
+
+    # One page per camera, named with the slugs the aggregation stored. The
+    # colliding labels get distinct files (canon-eos-5d and canon-eos-5d-2).
+    test::assert_file_exists "$dist_dir/run1/camera-canon-eos-5d.html"
+    test::assert_file_exists "$dist_dir/run1/camera-canon-eos-5d-2.html"
+    test::assert_file_exists "$dist_dir/run1/camera-nikon-co-z6.html"
+
+    # The Canon EOS 5D page lists exactly its two photos as thumbnails linking to
+    # the full images under photos/, and not the other camera's photo.
+    html=$(cat "$dist_dir/run1/camera-canon-eos-5d.html")
+    test::assert_contains '<a href="../photos/a.jpg">' "$html"
+    test::assert_contains '<img class="thumb" src="../thumbs/a.jpg" />' "$html"
+    test::assert_contains '<a href="../photos/b.jpg">' "$html"
+    test::assert_not_contains 'photos/c.png' "$html"
+    test::assert_not_contains 'photos/d.jpg' "$html"
+    # Heading shows the (trusted) camera label and a back-to-stats link.
+    test::assert_contains 'Canon EOS 5D' "$html"
+    test::assert_contains '<a href="../stats.html">Back to stats</a>' "$html"
+
+    # The EXIF-derived label with & and < is HTML-escaped in the heading.
+    html=$(cat "$dist_dir/run1/camera-nikon-co-z6.html")
+    test::assert_contains 'Nikon &amp; Co &lt;Z6&gt;' "$html"
+    test::assert_not_contains 'Nikon & Co <Z6>' "$html"
+    test::assert_contains '<a href="../photos/c.png">' "$html"
+
+    # Output is deterministic: the second run is byte-identical to the first.
+    html=$(cat "$dist_dir/run1/camera-canon-eos-5d.html")
+    html_again=$(cat "$dist_dir/run2/camera-canon-eos-5d.html")
+    if [ "$html" != "$html_again" ]; then
+        printf 'FAIL: camera page not reproducible across runs\n' >&2
+        exit 1
+    fi
+    test::teardown
+}
+
 test_template_context_validator_fails_fast_without_errexit() {
     local output
     local -i status=0
@@ -5419,6 +5521,9 @@ main() {
         'render_stats_page renders sections and escapes EXIF labels' \
         test_render_stats_page_renders_sections_and_escapes
     test::run_case \
+        'render_camera_pages renders one page per camera' \
+        test_render_camera_pages_renders_one_page_per_camera
+    test::run_case \
         'template context validator fails fast without errexit' \
         test_template_context_validator_fails_fast_without_errexit
     test::run_case \