pm0 add stats page template and render function

Render the aggregated STATS_* counters from the om0 module into a static
stats.html. render_stats_page builds the variable-length body (camera
leaderboard, temporal/exposure/dimension histograms, format and enum
breakdowns) as HTML and hands it to the new stats.tmpl through a raw
context field, wrapping it with the shared header/footer the way
view/details pages do. Bars are pure CSS so the page stays JavaScript-free.

- new template share/templates/default/stats.tmpl (page chrome + body)
- render_stats_page <html_dir> <backhref> [page_name] plus small section
  builders in src/lib/stats.source.sh; EXIF-derived labels are HTML-escaped
- new TEMPLATE_RENDER_FIELD_SPECS field render_stats_body_html (context_raw)
  and 'stats' added to render_backhref_html's required list
- camera leaderboard entries link to camera-<slug>.html (um0 owns those)
- Stats nav link wired into the shared header bar
- tests cover leaderboard links, counts/percentages, a histogram section,
  &/< escaping, and omission of empty categories

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

6 files changed, 762 insertions, 2 deletions

diff --git a/bin/shuriken b/bin/shuriken
index 7ef01fc..f3a2044 100755
--- a/bin/shuriken
+++ b/bin/shuriken
@@ -606,7 +606,7 @@ 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'
+    'render_backhref_html|context_html|backhref|backhref|footer header preview splash details view stats'
     '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_current_date_text|current_date_html|||'
@@ -626,6 +626,7 @@ declare -ra TEMPLATE_RENDER_FIELD_SPECS=(
     'render_preview_num_html|context_html|preview_num|preview_num|preview details view'
     'render_redirect_page_html|context_html|redirect_page|redirect_page|redirect'
     'render_show_header_bar|context_raw|show_header_bar|show_header_bar|header'
+    'render_stats_body_html|context_raw|stats_body|stats_body|stats'
     'render_tarball_include|tarball_include|||'
     'render_tarball_name_html|context_html|tarball_name|tarball_name|footer'
     'render_thumbheight_html|config_html|THUMBHEIGHT||'
@@ -3278,6 +3279,302 @@ collect_photo_exif_stats() {
     done < <(incoming_image_files)
 }
 
+# ----------------------------------------------------------------------------
+# Rendering (task pm0)
+# ----------------------------------------------------------------------------
+# render_stats_page turns the STATS_* globals filled by the aggregation above
+# into a static stats.html. The page is variable-length (each category may be
+# empty, sparse, or large) which does not fit the fixed field-spec template
+# engine cleanly, so we follow the same approach view/details pages use for
+# their dynamic EXIF table: build the whole body as an HTML string here, hand it
+# to stats.tmpl through the raw context field stats_body, and let the engine wrap
+# it with the shared header/footer chrome. Bars are plain CSS (width as a percent
+# of the section's top bucket) so the output stays JavaScript-free.
+
+# Print the largest counter in the named stats array, or 0 when it is empty.
+# Used to scale each section's bars relative to its own busiest bucket.
+_stats_max_count() {
+    local -n counts_ref="$1"; shift
+    local key
+    local -i max=0
+
+    for key in "${!counts_ref[@]}"; do
+        if (( counts_ref[$key] > max )); then
+            max=${counts_ref[$key]}
+        fi
+    done
+    printf '%d' "$max"
+}
+
+# Print the integer percentage count/total (0 when total is 0). awk keeps the
+# rounding off bash integer math; STATS_TOTALS[photos] is the denominator.
+_stats_percent() {
+    local -ri count="$1"; shift
+    local -ri total="$1"; shift
+
+    if (( total <= 0 )); then
+        printf '0'
+        return
+    fi
+    awk -v c="$count" -v t="$total" 'BEGIN { printf "%.0f", 100 * c / t }'
+}
+
+# Emit one bar-chart <li>: an already-escaped label, a CSS-width bar scaled to
+# the section maximum, and the count plus its share of all photos. Callers escape
+# labels themselves because some come from EXIF (camera/lens) and some are
+# trusted bucket names we build internally.
+_stats_bar_row() {
+    local -r label_html="$1"; shift
+    local -ri count="$1"; shift
+    local -ri total="$1"; shift
+    local -ri max="$1"; shift
+    local -i width=0
+
+    if (( max > 0 )); then
+        width=$(( 100 * count / max ))
+    fi
+    printf '    <li>'
+    printf '<span class="stats-label">%s</span>' "$label_html"
+    printf '<span class="stats-bar-track">'
+    printf '<span class="stats-bar-fill" style="width:%d%%"></span></span>' \
+        "$width"
+    printf '<span class="stats-count">%d (%s%%)</span>' \
+        "$count" "$(_stats_percent "$count" "$total")"
+    printf '</li>\n'
+}
+
+# Open a <section> with an escaped heading and the <ul> bar container. Split from
+# the row emitters so every section shares identical chrome.
+_stats_section_open() {
+    local -r heading="$1"; shift
+    local heading_html
+
+    heading_html=$(_html_escape "$heading")
+    printf '<section class="stats-section">\n'
+    printf '<h2>%s</h2>\n' "$heading_html"
+    printf '<ul class="stats-bars">\n'
+}
+
+_stats_section_close() {
+    printf '</ul>\n</section>\n'
+}
+
+# Render the camera leaderboard: one bar per camera, sorted by count descending,
+# each label linking to camera-<slug>.html (built by sibling task um0). Camera
+# labels come from EXIF, so the label text is HTML-escaped; the slug is filename
+# -safe by construction. Skipped entirely when no camera data was collected.
+_stats_render_camera_section() {
+    local -ri total="$1"; shift
+    local label
+    local label_html
+    local link_html
+    local slug
+    local -i max
+
+    if (( ${#STATS_CAMERAS[@]} == 0 )); then
+        return
+    fi
+    max=$(_stats_max_count STATS_CAMERAS)
+    _stats_section_open 'Camera leaderboard'
+    while IFS= read -r label; do
+        label_html=$(_html_escape "$label")
+        slug="${STATS_CAMERA_SLUGS[$label]}"
+        link_html=$(printf '<a href="camera-%s.html">%s</a>' \
+            "$slug" "$label_html")
+        _stats_bar_row "$link_html" "${STATS_CAMERAS[$label]}" "$total" "$max"
+    done < <(_stats_keys_by_count_desc STATS_CAMERAS)
+    _stats_section_close
+}
+
+# Print an array's keys ordered by descending count (ties broken by key) so the
+# busiest bucket leads. Used for the leaderboard and other count-ranked sections.
+_stats_keys_by_count_desc() {
+    local -n counts_ref="$1"; shift
+    local key
+
+    for key in "${!counts_ref[@]}"; do
+        printf '%d\t%s\n' "${counts_ref[$key]}" "$key"
+    done | sort -t $'\t' -k1,1nr -k2,2 | cut -f2-
+}
+
+# Render a histogram section using an explicit bucket order (e.g. apertures from
+# wide to narrow) rather than count ranking, so the axis reads naturally. Only
+# buckets that actually occurred are emitted, and the whole section is skipped
+# when none did. Bucket labels are internal/trusted but still escaped for safety.
+_stats_render_ordered_section() {
+    local -r heading="$1"; shift
+    local -r array_name="$1"; shift
+    local -ri total="$1"; shift
+    local -n counts_ref="$array_name"
+    local bucket
+    local label_html
+    local -i max
+
+    if (( ${#counts_ref[@]} == 0 )); then
+        return
+    fi
+    max=$(_stats_max_count "$array_name")
+    _stats_section_open "$heading"
+    for bucket in "$@"; do
+        if [ -z "${counts_ref[$bucket]:-}" ]; then
+            continue
+        fi
+        label_html=$(_html_escape "$bucket")
+        _stats_bar_row "$label_html" "${counts_ref[$bucket]}" "$total" "$max"
+    done
+    _stats_section_close
+}
+
+# Render a section ranked by count (cameras aside). Used where there is no
+# natural axis order: years, lenses, and the decoded enum categories.
+_stats_render_ranked_section() {
+    local -r heading="$1"; shift
+    local -r array_name="$1"; shift
+    local -ri total="$1"; shift
+    local -n counts_ref="$array_name"
+    local key
+    local label_html
+    local -i max
+
+    if (( ${#counts_ref[@]} == 0 )); then
+        return
+    fi
+    max=$(_stats_max_count "$array_name")
+    _stats_section_open "$heading"
+    while IFS= read -r key; do
+        label_html=$(_html_escape "$key")
+        _stats_bar_row "$label_html" "${counts_ref[$key]}" "$total" "$max"
+    done < <(_stats_keys_by_count_desc "$array_name")
+    _stats_section_close
+}
+
+# Render the temporal sections. Years rank by count; months walk Jan..Dec in
+# calendar order using human month names for the labels.
+_stats_render_temporal_sections() {
+    local -ri total="$1"; shift
+
+    _stats_render_ranked_section 'Photos per year' STATS_YEARS "$total"
+    _stats_render_month_section "$total"
+}
+
+# Render the per-month histogram in calendar order. The aggregator keys months
+# by zero-padded number (01..12); this maps each to its English name so the axis
+# is readable, and reuses the ordered-section omit-when-empty behaviour inline.
+_stats_render_month_section() {
+    local -ri total="$1"; shift
+    local -ra month_names=(
+        '' January February March April May June July August
+        September October November December )
+    local -i month
+    local key
+    local -i max
+
+    if (( ${#STATS_MONTHS[@]} == 0 )); then
+        return
+    fi
+    max=$(_stats_max_count STATS_MONTHS)
+    _stats_section_open 'Photos per month'
+    for (( month = 1; month <= 12; month++ )); do
+        key=$(printf '%02d' "$month")
+        if [ -z "${STATS_MONTHS[$key]:-}" ]; then
+            continue
+        fi
+        _stats_bar_row "${month_names[$month]}" \
+            "${STATS_MONTHS[$key]}" "$total" "$max"
+    done
+    _stats_section_close
+}
+
+# Render the exposure histograms in photographer-friendly axis order (the same
+# bucket ladders the aggregator's *_bucket helpers produce).
+_stats_render_exposure_sections() {
+    local -ri total="$1"; shift
+
+    _stats_render_ordered_section 'Aperture' STATS_APERTURE "$total" \
+        'f/1.8 or wider' 'f/2' 'f/2.8' 'f/4' 'f/5.6' 'f/8' 'f/11' 'f/16' \
+        'f/22 or narrower'
+    _stats_render_ordered_section 'Shutter speed' STATS_SHUTTER "$total" \
+        '1/4000s or faster' '1/2000s' '1/1000s' '1/500s' '1/250s' '1/125s' \
+        '1/60s' '1/30s' '1/15s' '1/8s' '1/4s' '1/2s' '1s' 'longer than 1s'
+    _stats_render_ordered_section 'ISO' STATS_ISO "$total" \
+        '50' '100' '200' '400' '800' '1600' '3200' '6400' '12800' '25600' \
+        'over 25600'
+    _stats_render_ordered_section 'Focal length' STATS_FOCAL "$total" \
+        'under 24mm' '24-35mm' '35-70mm' '70-135mm' '135-200mm' 'over 200mm'
+}
+
+# Render the dimension histograms (megapixels, aspect ratio, orientation) and
+# the file-format breakdown, each in its natural axis order.
+_stats_render_dimension_sections() {
+    local -ri total="$1"; shift
+
+    _stats_render_ordered_section 'Megapixels' STATS_MEGAPIXELS "$total" \
+        'under 2MP' '2-5MP' '5-10MP' '10-20MP' '20-40MP' '40-80MP' 'over 80MP'
+    _stats_render_ordered_section 'Aspect ratio' STATS_ASPECT "$total" \
+        '3:2' '4:3' '16:9' '1:1' '5:4' 'other'
+    _stats_render_ordered_section 'Orientation' STATS_ORIENTATION "$total" \
+        'Landscape' 'Portrait' 'Square'
+    _stats_render_ordered_section 'File format' STATS_FORMAT "$total" \
+        'JPEG' 'PNG' 'WEBP' 'GIF' 'other'
+}
+
+# Render the decoded enum sections and the (sparse) lens leaderboard. All rank by
+# count and self-skip when empty, so absent tags simply omit their section.
+_stats_render_enum_sections() {
+    local -ri total="$1"; shift
+
+    _stats_render_ranked_section 'Lenses' STATS_LENSES "$total"
+    _stats_render_ranked_section 'Exposure program' \
+        STATS_EXPOSURE_PROGRAM "$total"
+    _stats_render_ranked_section 'Metering mode' STATS_METERING "$total"
+    _stats_render_ranked_section 'White balance' STATS_WHITE_BALANCE "$total"
+    _stats_render_ranked_section 'Flash' STATS_FLASH "$total"
+}
+
+# Assemble the full stats body from every section in display order. Returns the
+# HTML on stdout; render_stats_page captures it into the stats_body context var.
+_stats_build_body() {
+    local -ri total="${STATS_TOTALS[photos]:-0}"
+
+    printf '<p class="stats-total">%d photos analysed.</p>\n' "$total"
+    _stats_render_camera_section "$total"
+    _stats_render_temporal_sections "$total"
+    _stats_render_exposure_sections "$total"
+    _stats_render_dimension_sections "$total"
+    _stats_render_enum_sections "$total"
+}
+
+# Public render entry point (handoff for task rm0). Builds the body from the
+# already-populated STATS_* globals and renders stats.html via the template
+# engine, wrapping the body with the shared header/footer the way view/details
+# pages do. Call collect_photo_exif_stats first to fill the globals.
+#   render_stats_page <html_dir> <backhref> [page_name]
+# 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
+# stats.html), and page_name defaults to "stats" -> stats.html.
+render_stats_page() {
+    local -r html_dir="$1"; shift
+    local -r backhref="$1"; shift
+    local -r page_name="${1:-stats}"
+    local stats_body
+
+    stats_body=$(_stats_build_body)
+    template header "$page_name.html" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        blurs_dir '' \
+        background_image '' \
+        show_header_bar 'yes'
+    template stats "$page_name.html" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        stats_body "$stats_body"
+    template footer "$page_name.html" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        tarball_name ''
+}
+
 # Inlined from src/lib/config.source.sh
 existing_parent_dir() {
     local -r path="$1"; shift
diff --git a/share/templates/default/header.tmpl b/share/templates/default/header.tmpl
index 953109a..e0acc6f 100644
--- a/share/templates/default/header.tmpl
+++ b/share/templates/default/header.tmpl
@@ -95,6 +95,67 @@ cat <<END
             white-space: nowrap;
         }
 
+        div.stats {
+            margin: 0 auto;
+            max-width: 900px;
+            text-align: left;
+        }
+
+        h1.stats-title {
+            text-align: center;
+        }
+
+        section.stats-section {
+            background-color: #000000;
+            border: 3px solid #ffffff;
+            margin: 8px auto;
+            padding: 10px;
+        }
+
+        section.stats-section h2 {
+            font-size: 1.1em;
+            margin-top: 0;
+        }
+
+        /* Each bar row is a label, a proportional bar, and the count/percent.
+           Bars are pure CSS (width as a percentage of the top bucket) so the
+           page stays static HTML with no JavaScript or SVG. */
+        ul.stats-bars {
+            list-style: none;
+            margin: 0;
+            padding: 0;
+        }
+
+        ul.stats-bars li {
+            align-items: center;
+            display: flex;
+            gap: 8px;
+            margin: 2px 0;
+        }
+
+        span.stats-label {
+            flex: 0 0 9em;
+            word-break: break-word;
+        }
+
+        span.stats-bar-track {
+            background-color: #222222;
+            flex: 1 1 auto;
+            height: 1.1em;
+        }
+
+        span.stats-bar-fill {
+            background-color: #ffffff;
+            display: block;
+            height: 100%;
+        }
+
+        span.stats-count {
+            flex: 0 0 7em;
+            text-align: right;
+            white-space: nowrap;
+        }
+
         img {
             padding: 5px;
         }
@@ -215,6 +276,8 @@ cat <<END
     Site generated at ${render_current_date_text} with <a href="https://codeberg.org/snonux/shuriken.sh">codeberg.org/snonux/shuriken.sh</a>
     -
     &copy; by Paul Buetow
+    -
+    <a href="${render_backhref_html}/stats.html">Stats</a>
 </div>
 END
 fi
diff --git a/share/templates/default/stats.tmpl b/share/templates/default/stats.tmpl
new file mode 100644
index 0000000..7a94b60
--- /dev/null
+++ b/share/templates/default/stats.tmpl
@@ -0,0 +1,16 @@
+# Stats page body. All of the variable-length, data-driven markup (camera
+# leaderboard, histograms, format breakdown, enum tables) is pre-rendered by
+# render_stats_page in src/lib/stats.source.sh and handed in through the raw
+# context field render_stats_body_html, so this template only supplies the page
+# chrome: the heading, the pre-built body, and a link back to the album. The
+# surrounding <html>/<head>/<body> and footer come from the header/footer
+# templates, which render_stats_page emits around this one (same as view/details).
+cat <<END
+<div class="view stats">
+    <h1 class="stats-title">${render_title_html} &mdash; Stats</h1>
+    <div class="stats-back navigator">
+        <a href="${render_backhref_html}/index.html">Back to album</a>
+    </div>
+    ${render_stats_body_html}
+</div>
+END
diff --git a/src/lib/stats.source.sh b/src/lib/stats.source.sh
index cdb8668..f4f2e1f 100644
--- a/src/lib/stats.source.sh
+++ b/src/lib/stats.source.sh
@@ -548,3 +548,299 @@ collect_photo_exif_stats() {
             < <(cached_photo_identify_output "$photo" "$INCOMING_DIR/$photo")
     done < <(incoming_image_files)
 }
+
+# ----------------------------------------------------------------------------
+# Rendering (task pm0)
+# ----------------------------------------------------------------------------
+# render_stats_page turns the STATS_* globals filled by the aggregation above
+# into a static stats.html. The page is variable-length (each category may be
+# empty, sparse, or large) which does not fit the fixed field-spec template
+# engine cleanly, so we follow the same approach view/details pages use for
+# their dynamic EXIF table: build the whole body as an HTML string here, hand it
+# to stats.tmpl through the raw context field stats_body, and let the engine wrap
+# it with the shared header/footer chrome. Bars are plain CSS (width as a percent
+# of the section's top bucket) so the output stays JavaScript-free.
+
+# Print the largest counter in the named stats array, or 0 when it is empty.
+# Used to scale each section's bars relative to its own busiest bucket.
+_stats_max_count() {
+    local -n counts_ref="$1"; shift
+    local key
+    local -i max=0
+
+    for key in "${!counts_ref[@]}"; do
+        if (( counts_ref[$key] > max )); then
+            max=${counts_ref[$key]}
+        fi
+    done
+    printf '%d' "$max"
+}
+
+# Print the integer percentage count/total (0 when total is 0). awk keeps the
+# rounding off bash integer math; STATS_TOTALS[photos] is the denominator.
+_stats_percent() {
+    local -ri count="$1"; shift
+    local -ri total="$1"; shift
+
+    if (( total <= 0 )); then
+        printf '0'
+        return
+    fi
+    awk -v c="$count" -v t="$total" 'BEGIN { printf "%.0f", 100 * c / t }'
+}
+
+# Emit one bar-chart <li>: an already-escaped label, a CSS-width bar scaled to
+# the section maximum, and the count plus its share of all photos. Callers escape
+# labels themselves because some come from EXIF (camera/lens) and some are
+# trusted bucket names we build internally.
+_stats_bar_row() {
+    local -r label_html="$1"; shift
+    local -ri count="$1"; shift
+    local -ri total="$1"; shift
+    local -ri max="$1"; shift
+    local -i width=0
+
+    if (( max > 0 )); then
+        width=$(( 100 * count / max ))
+    fi
+    printf '    <li>'
+    printf '<span class="stats-label">%s</span>' "$label_html"
+    printf '<span class="stats-bar-track">'
+    printf '<span class="stats-bar-fill" style="width:%d%%"></span></span>' \
+        "$width"
+    printf '<span class="stats-count">%d (%s%%)</span>' \
+        "$count" "$(_stats_percent "$count" "$total")"
+    printf '</li>\n'
+}
+
+# Open a <section> with an escaped heading and the <ul> bar container. Split from
+# the row emitters so every section shares identical chrome.
+_stats_section_open() {
+    local -r heading="$1"; shift
+    local heading_html
+
+    heading_html=$(_html_escape "$heading")
+    printf '<section class="stats-section">\n'
+    printf '<h2>%s</h2>\n' "$heading_html"
+    printf '<ul class="stats-bars">\n'
+}
+
+_stats_section_close() {
+    printf '</ul>\n</section>\n'
+}
+
+# Render the camera leaderboard: one bar per camera, sorted by count descending,
+# each label linking to camera-<slug>.html (built by sibling task um0). Camera
+# labels come from EXIF, so the label text is HTML-escaped; the slug is filename
+# -safe by construction. Skipped entirely when no camera data was collected.
+_stats_render_camera_section() {
+    local -ri total="$1"; shift
+    local label
+    local label_html
+    local link_html
+    local slug
+    local -i max
+
+    if (( ${#STATS_CAMERAS[@]} == 0 )); then
+        return
+    fi
+    max=$(_stats_max_count STATS_CAMERAS)
+    _stats_section_open 'Camera leaderboard'
+    while IFS= read -r label; do
+        label_html=$(_html_escape "$label")
+        slug="${STATS_CAMERA_SLUGS[$label]}"
+        link_html=$(printf '<a href="camera-%s.html">%s</a>' \
+            "$slug" "$label_html")
+        _stats_bar_row "$link_html" "${STATS_CAMERAS[$label]}" "$total" "$max"
+    done < <(_stats_keys_by_count_desc STATS_CAMERAS)
+    _stats_section_close
+}
+
+# Print an array's keys ordered by descending count (ties broken by key) so the
+# busiest bucket leads. Used for the leaderboard and other count-ranked sections.
+_stats_keys_by_count_desc() {
+    local -n counts_ref="$1"; shift
+    local key
+
+    for key in "${!counts_ref[@]}"; do
+        printf '%d\t%s\n' "${counts_ref[$key]}" "$key"
+    done | sort -t $'\t' -k1,1nr -k2,2 | cut -f2-
+}
+
+# Render a histogram section using an explicit bucket order (e.g. apertures from
+# wide to narrow) rather than count ranking, so the axis reads naturally. Only
+# buckets that actually occurred are emitted, and the whole section is skipped
+# when none did. Bucket labels are internal/trusted but still escaped for safety.
+_stats_render_ordered_section() {
+    local -r heading="$1"; shift
+    local -r array_name="$1"; shift
+    local -ri total="$1"; shift
+    local -n counts_ref="$array_name"
+    local bucket
+    local label_html
+    local -i max
+
+    if (( ${#counts_ref[@]} == 0 )); then
+        return
+    fi
+    max=$(_stats_max_count "$array_name")
+    _stats_section_open "$heading"
+    for bucket in "$@"; do
+        if [ -z "${counts_ref[$bucket]:-}" ]; then
+            continue
+        fi
+        label_html=$(_html_escape "$bucket")
+        _stats_bar_row "$label_html" "${counts_ref[$bucket]}" "$total" "$max"
+    done
+    _stats_section_close
+}
+
+# Render a section ranked by count (cameras aside). Used where there is no
+# natural axis order: years, lenses, and the decoded enum categories.
+_stats_render_ranked_section() {
+    local -r heading="$1"; shift
+    local -r array_name="$1"; shift
+    local -ri total="$1"; shift
+    local -n counts_ref="$array_name"
+    local key
+    local label_html
+    local -i max
+
+    if (( ${#counts_ref[@]} == 0 )); then
+        return
+    fi
+    max=$(_stats_max_count "$array_name")
+    _stats_section_open "$heading"
+    while IFS= read -r key; do
+        label_html=$(_html_escape "$key")
+        _stats_bar_row "$label_html" "${counts_ref[$key]}" "$total" "$max"
+    done < <(_stats_keys_by_count_desc "$array_name")
+    _stats_section_close
+}
+
+# Render the temporal sections. Years rank by count; months walk Jan..Dec in
+# calendar order using human month names for the labels.
+_stats_render_temporal_sections() {
+    local -ri total="$1"; shift
+
+    _stats_render_ranked_section 'Photos per year' STATS_YEARS "$total"
+    _stats_render_month_section "$total"
+}
+
+# Render the per-month histogram in calendar order. The aggregator keys months
+# by zero-padded number (01..12); this maps each to its English name so the axis
+# is readable, and reuses the ordered-section omit-when-empty behaviour inline.
+_stats_render_month_section() {
+    local -ri total="$1"; shift
+    local -ra month_names=(
+        '' January February March April May June July August
+        September October November December )
+    local -i month
+    local key
+    local -i max
+
+    if (( ${#STATS_MONTHS[@]} == 0 )); then
+        return
+    fi
+    max=$(_stats_max_count STATS_MONTHS)
+    _stats_section_open 'Photos per month'
+    for (( month = 1; month <= 12; month++ )); do
+        key=$(printf '%02d' "$month")
+        if [ -z "${STATS_MONTHS[$key]:-}" ]; then
+            continue
+        fi
+        _stats_bar_row "${month_names[$month]}" \
+            "${STATS_MONTHS[$key]}" "$total" "$max"
+    done
+    _stats_section_close
+}
+
+# Render the exposure histograms in photographer-friendly axis order (the same
+# bucket ladders the aggregator's *_bucket helpers produce).
+_stats_render_exposure_sections() {
+    local -ri total="$1"; shift
+
+    _stats_render_ordered_section 'Aperture' STATS_APERTURE "$total" \
+        'f/1.8 or wider' 'f/2' 'f/2.8' 'f/4' 'f/5.6' 'f/8' 'f/11' 'f/16' \
+        'f/22 or narrower'
+    _stats_render_ordered_section 'Shutter speed' STATS_SHUTTER "$total" \
+        '1/4000s or faster' '1/2000s' '1/1000s' '1/500s' '1/250s' '1/125s' \
+        '1/60s' '1/30s' '1/15s' '1/8s' '1/4s' '1/2s' '1s' 'longer than 1s'
+    _stats_render_ordered_section 'ISO' STATS_ISO "$total" \
+        '50' '100' '200' '400' '800' '1600' '3200' '6400' '12800' '25600' \
+        'over 25600'
+    _stats_render_ordered_section 'Focal length' STATS_FOCAL "$total" \
+        'under 24mm' '24-35mm' '35-70mm' '70-135mm' '135-200mm' 'over 200mm'
+}
+
+# Render the dimension histograms (megapixels, aspect ratio, orientation) and
+# the file-format breakdown, each in its natural axis order.
+_stats_render_dimension_sections() {
+    local -ri total="$1"; shift
+
+    _stats_render_ordered_section 'Megapixels' STATS_MEGAPIXELS "$total" \
+        'under 2MP' '2-5MP' '5-10MP' '10-20MP' '20-40MP' '40-80MP' 'over 80MP'
+    _stats_render_ordered_section 'Aspect ratio' STATS_ASPECT "$total" \
+        '3:2' '4:3' '16:9' '1:1' '5:4' 'other'
+    _stats_render_ordered_section 'Orientation' STATS_ORIENTATION "$total" \
+        'Landscape' 'Portrait' 'Square'
+    _stats_render_ordered_section 'File format' STATS_FORMAT "$total" \
+        'JPEG' 'PNG' 'WEBP' 'GIF' 'other'
+}
+
+# Render the decoded enum sections and the (sparse) lens leaderboard. All rank by
+# count and self-skip when empty, so absent tags simply omit their section.
+_stats_render_enum_sections() {
+    local -ri total="$1"; shift
+
+    _stats_render_ranked_section 'Lenses' STATS_LENSES "$total"
+    _stats_render_ranked_section 'Exposure program' \
+        STATS_EXPOSURE_PROGRAM "$total"
+    _stats_render_ranked_section 'Metering mode' STATS_METERING "$total"
+    _stats_render_ranked_section 'White balance' STATS_WHITE_BALANCE "$total"
+    _stats_render_ranked_section 'Flash' STATS_FLASH "$total"
+}
+
+# Assemble the full stats body from every section in display order. Returns the
+# HTML on stdout; render_stats_page captures it into the stats_body context var.
+_stats_build_body() {
+    local -ri total="${STATS_TOTALS[photos]:-0}"
+
+    printf '<p class="stats-total">%d photos analysed.</p>\n' "$total"
+    _stats_render_camera_section "$total"
+    _stats_render_temporal_sections "$total"
+    _stats_render_exposure_sections "$total"
+    _stats_render_dimension_sections "$total"
+    _stats_render_enum_sections "$total"
+}
+
+# Public render entry point (handoff for task rm0). Builds the body from the
+# already-populated STATS_* globals and renders stats.html via the template
+# engine, wrapping the body with the shared header/footer the way view/details
+# pages do. Call collect_photo_exif_stats first to fill the globals.
+#   render_stats_page <html_dir> <backhref> [page_name]
+# 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
+# stats.html), and page_name defaults to "stats" -> stats.html.
+render_stats_page() {
+    local -r html_dir="$1"; shift
+    local -r backhref="$1"; shift
+    local -r page_name="${1:-stats}"
+    local stats_body
+
+    stats_body=$(_stats_build_body)
+    template header "$page_name.html" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        blurs_dir '' \
+        background_image '' \
+        show_header_bar 'yes'
+    template stats "$page_name.html" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        stats_body "$stats_body"
+    template footer "$page_name.html" \
+        html_dir "$html_dir" \
+        backhref "$backhref" \
+        tarball_name ''
+}
diff --git a/src/lib/template.source.sh b/src/lib/template.source.sh
index c23b870..6d48ae5 100644
--- a/src/lib/template.source.sh
+++ b/src/lib/template.source.sh
@@ -144,7 +144,7 @@ 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'
+    'render_backhref_html|context_html|backhref|backhref|footer header preview splash details view stats'
     '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_current_date_text|current_date_html|||'
@@ -164,6 +164,7 @@ declare -ra TEMPLATE_RENDER_FIELD_SPECS=(
     'render_preview_num_html|context_html|preview_num|preview_num|preview details view'
     'render_redirect_page_html|context_html|redirect_page|redirect_page|redirect'
     'render_show_header_bar|context_raw|show_header_bar|show_header_bar|header'
+    'render_stats_body_html|context_raw|stats_body|stats_body|stats'
     'render_tarball_include|tarball_include|||'
     'render_tarball_name_html|context_html|tarball_name|tarball_name|footer'
     'render_thumbheight_html|config_html|THUMBHEIGHT||'
diff --git a/tests/cli.sh b/tests/cli.sh
index 423bc49..48efc17 100755
--- a/tests/cli.sh
+++ b/tests/cli.sh
@@ -3700,6 +3700,7 @@ prev:html_dir prev
 preview:animation_class backhref html_dir page_num photo preview_num thumbs_dir
 redirect:html_dir redirect_page
 splash:backhref background_image blurs_dir enter_page html_dir photo photos_dir
+stats:backhref html_dir stats_body
 view:animation_class backhref html_dir page_num photo photos_dir preview_num
 END
     )
@@ -3716,6 +3717,7 @@ declare -a template_names=(
     preview
     redirect
     splash
+    stats
     view
 )
 
@@ -3737,6 +3739,88 @@ BASH
     fi
 }
 
+test_render_stats_page_renders_sections_and_escapes() {
+    local html
+    local output_file
+
+    test::setup
+    output_file="$TEST_TMPDIR/dist/stats.html"
+    mkdir -p "$TEST_TMPDIR/dist"
+
+    # Feed synthetic EXIF straight into accumulate_photo_stats so the test does
+    # not depend on the cache layer, then render. The second camera label carries
+    # & and < to prove EXIF-derived labels are HTML-escaped.
+    bash -euo pipefail -s \
+        "$TEST_SHURIKEN" \
+        "$TEST_REPO_ROOT/share/templates/default" \
+        "$TEST_TMPDIR/dist" \
+        <<'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="$template_dir"
+TITLE='Stats album'
+HEIGHT=600
+THUMBHEIGHT=120
+MAXPREVIEWS=40
+ORIGINAL_BASEPATH=''
+TARBALL_INCLUDE=no
+SHURIKEN_OUTPUT_MODE=quiet
+apply_config_defaults
+
+reset_photo_exif_stats
+accumulate_photo_stats 'a.jpg' <<'EXIF'
+  Geometry: 6000x4000+0+0
+  exif:Make: Canon
+  exif:Model: Canon EOS 5D
+  exif:FNumber: 28/10
+  exif:ISOSpeedRatings: 400
+  exif:DateTimeOriginal: 2021:06:14 10:00:00
+EXIF
+accumulate_photo_stats 'b.jpg' <<'EXIF'
+  Geometry: 6000x4000+0+0
+  exif:Make: Canon
+  exif:Model: Canon EOS 5D
+  exif:DateTimeOriginal: 2021:06:14 10:00:00
+EXIF
+accumulate_photo_stats 'c.png' <<'EXIF'
+  Geometry: 4000x6000+0+0
+  exif:Make: Nikon & Co
+  exif:Model: <Z6>
+  exif:DateTimeOriginal: 2022:07:14 10:00:00
+EXIF
+
+render_stats_page . .
+BASH
+
+    html=$(cat "$output_file")
+
+    # Leaderboard entry links to camera-<slug>.html with the right count/percent.
+    test::assert_contains \
+        '<a href="camera-canon-eos-5d.html">Canon EOS 5D</a>' "$html"
+    test::assert_contains '2 (67%)' "$html"
+    # A histogram section is present.
+    test::assert_contains '<h2>ISO</h2>' "$html"
+    test::assert_contains '400' "$html"
+    # EXIF-derived label with & and < is HTML-escaped, not raw markup.
+    test::assert_contains 'Nikon &amp; Co &lt;Z6&gt;' "$html"
+    test::assert_not_contains 'Nikon & Co <Z6>' "$html"
+    # Total photo count drives the percentage denominator.
+    test::assert_contains '3 photos analysed.' "$html"
+    # The Stats nav link is wired into the shared header.
+    test::assert_contains '>Stats</a>' "$html"
+    # Empty categories are omitted (no flash/lens/shutter data was supplied).
+    test::assert_not_contains '<h2>Flash</h2>' "$html"
+    test::assert_not_contains '<h2>Lenses</h2>' "$html"
+    test::assert_not_contains '<h2>Shutter speed</h2>' "$html"
+    test::teardown
+}
+
 test_template_context_validator_fails_fast_without_errexit() {
     local output
     local -i status=0
@@ -5332,6 +5416,9 @@ main() {
         'template required context vars come from render specs' \
         test_template_required_context_vars_come_from_render_specs
     test::run_case \
+        'render_stats_page renders sections and escapes EXIF labels' \
+        test_render_stats_page_renders_sections_and_escapes
+    test::run_case \
         'template context validator fails fast without errexit' \
         test_template_context_validator_fails_fast_without_errexit
     test::run_case \