Fix stats gauge bars rendering at width:0% (stats_category_max)

Regression from or0 (STATS_* accessors): stats_category_max compared
values via `(( _stats_counts_ref[key] > max ))`. For a nameref to an
ASSOCIATIVE array, an arithmetic subscript is itself arithmetic-evaluated,
so a string key (e.g. "sony") resolves to an unset variable -> 0, i.e. it
always read index 0 and returned max 0. Every bar then scaled to
width:0% (counts/percentages were unaffected, so only the bars looked
broken). Read the value through a quoted ${assoc[$key]} expansion first,
then compare.

The byte-identical double-render test missed this because both renders
were equally broken; added explicit non-zero bar-width assertions
(100% / 50%) to test_render_stats_page_renders_sections_and_escapes.

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

3 files changed, 28 insertions, 4 deletions

diff --git a/bin/shuriken b/bin/shuriken
index 0b1afa2..a753b9a 100755
--- a/bin/shuriken
+++ b/bin/shuriken
@@ -5046,11 +5046,19 @@ stats_category_size() {
 stats_category_max() {
     local -n _stats_counts_ref="$1"; shift
     local key
+    local -i value
     local -i max=0
 
     for key in "${!_stats_counts_ref[@]}"; do
-        if (( _stats_counts_ref[key] > max )); then
-            max=${_stats_counts_ref[$key]}
+        # Read the value through a quoted ${assoc[$key]} expansion FIRST, then
+        # compare. Do NOT write "(( _stats_counts_ref[key] > max ))": inside an
+        # arithmetic context an associative subscript is itself arithmetic-
+        # evaluated, so a string key (e.g. "sony") resolves to an unset var -> 0,
+        # i.e. it would always read index 0 and report max 0 (broken zero-width
+        # bars). The string-keyed expansion below is the only correct read.
+        value=${_stats_counts_ref[$key]}
+        if (( value > max )); then
+            max=$value
         fi
     done
     printf '%d' "$max"
diff --git a/src/lib/stats-aggregate.source.sh b/src/lib/stats-aggregate.source.sh
index 3c013b3..ff06d15 100644
--- a/src/lib/stats-aggregate.source.sh
+++ b/src/lib/stats-aggregate.source.sh
@@ -772,11 +772,19 @@ stats_category_size() {
 stats_category_max() {
     local -n _stats_counts_ref="$1"; shift
     local key
+    local -i value
     local -i max=0
 
     for key in "${!_stats_counts_ref[@]}"; do
-        if (( _stats_counts_ref[key] > max )); then
-            max=${_stats_counts_ref[$key]}
+        # Read the value through a quoted ${assoc[$key]} expansion FIRST, then
+        # compare. Do NOT write "(( _stats_counts_ref[key] > max ))": inside an
+        # arithmetic context an associative subscript is itself arithmetic-
+        # evaluated, so a string key (e.g. "sony") resolves to an unset var -> 0,
+        # i.e. it would always read index 0 and report max 0 (broken zero-width
+        # bars). The string-keyed expansion below is the only correct read.
+        value=${_stats_counts_ref[$key]}
+        if (( value > max )); then
+            max=$value
         fi
     done
     printf '%d' "$max"
diff --git a/tests/cli.sh b/tests/cli.sh
index ca5d170..cc0bd1c 100755
--- a/tests/cli.sh
+++ b/tests/cli.sh
@@ -4799,6 +4799,14 @@ BASH
     test::assert_contains \
         '<a href="camera-canon-eos-5d/index.html">Canon EOS 5D</a>' "$html"
     test::assert_contains '2 (67%)' "$html"
+    # Gauge bars scale each bucket to its section's busiest bucket: with 2 Canon
+    # vs 1 Nikon the camera bars are 100% and 50% wide. Regression guard: a prior
+    # stats_category_max bug (arithmetic subscript on an associative-array nameref
+    # resolving the string key to 0) returned max 0, collapsing EVERY bar to
+    # width:0%. Asserting the non-zero widths catches that; the byte-identical
+    # double-render test could not (both renders were equally broken).
+    test::assert_contains 'class="stats-bar-fill" style="width:100%"' "$html"
+    test::assert_contains 'class="stats-bar-fill" style="width:50%"' "$html"
     # A histogram section is present.
     test::assert_contains '<h2>ISO</h2>' "$html"
     test::assert_contains '400' "$html"