diff --git a/plugins/statusline/assets/costs.sh b/plugins/statusline/assets/costs.sh
index ae621d3..cff374a 100755
--- a/plugins/statusline/assets/costs.sh
+++ b/plugins/statusline/assets/costs.sh
@@ -51,6 +51,15 @@
 #   used to exercise the day/month rollover branches deterministically (e.g. the
 #   month-boundary transition). Unset in production; real `date` is used.
 
+# Numeric formatting must be locale-independent. Under a comma-decimal locale
+# (e.g. fr_FR) awk/printf emit "19,78"; interpolated into a downstream awk
+# program that value is read as TWO arguments and the amount is truncated.
+# Only the numeric category is forced, matching statusline-command.sh: LC_ALL=C
+# would also pin LC_CTYPE, which breaks ${#s} width measurement. LC_ALL must be
+# unset first — it outranks LC_NUMERIC when the environment sets it.
+unset LC_ALL
+export LC_NUMERIC=C
+
 set -u
 
 COST_LOG="${STATUSLINE_COST_LOG:-${HOME}/.claude/statusline-costs.jsonl}"
diff --git a/plugins/statusline/assets/statusline-command.sh b/plugins/statusline/assets/statusline-command.sh
index 34784a1..7d6ba34 100755
--- a/plugins/statusline/assets/statusline-command.sh
+++ b/plugins/statusline/assets/statusline-command.sh
@@ -63,6 +63,16 @@
 # (test harnesses pointing at a working copy).
 # Load order is dependency order: platform and palette own no dependencies,
 # everything else builds on them.
+# Numeric formatting must be locale-independent. Under a comma-decimal locale
+# (e.g. fr_FR) awk/printf emit "19,78"; interpolated into a downstream awk
+# program that value is read as TWO arguments and the amount is truncated.
+# Only the numeric category may be forced: LC_ALL=C would also pin LC_CTYPE,
+# and vislen() measures with ${#s}, which then counts UTF-8 bytes instead of
+# columns (a 3-byte glyph reads as width 3). LC_ALL must be unset first —
+# it outranks LC_NUMERIC when the environment sets it.
+unset LC_ALL
+export LC_NUMERIC=C
+
 STATUSLINE_LIB="${STATUSLINE_LIB:-$(cd "$(dirname "${BASH_SOURCE[0]}")" 2>/dev/null && pwd)/statusline-lib}"
 for _mod in platform palette fit severity format config gitctx session_state layout render; do
   if [ -r "${STATUSLINE_LIB}/${_mod}.sh" ]; then
diff --git a/plugins/statusline/assets/statusline-lib/format.sh b/plugins/statusline/assets/statusline-lib/format.sh
index 7299445..74b4abf 100644
--- a/plugins/statusline/assets/statusline-lib/format.sh
+++ b/plugins/statusline/assets/statusline-lib/format.sh
@@ -19,8 +19,11 @@ fmt_tokens() {
 
 # fmt_usd — a dollar amount, thousands folded to "$1.2k".
 fmt_usd() {
-  local v="$1"
-  LC_NUMERIC=C awk "BEGIN{ if($v>=1000) printf \"\$%.1fk\",$v/1000; else printf \"\$%.2f\",$v }"
+  # Value passed via -v, never interpolated into the program text: a stray
+  # comma decimal must not become an argument separator.
+  local v="${1:-0}"
+  v="${v/,/.}"
+  LC_ALL=C awk -v v="$v" 'BEGIN{ v=v+0; if (v>=1000) printf "$%.1fk", v/1000; else printf "$%.2f", v }'
 }
 
 # fmt_dur — compact duration: "Xh Ym" / "Xm Ys" / "Xs" from a seconds count.
diff --git a/plugins/statusline/assets/statusline-lib/render.sh b/plugins/statusline/assets/statusline-lib/render.sh
index 95e961c..f67c516 100644
--- a/plugins/statusline/assets/statusline-lib/render.sh
+++ b/plugins/statusline/assets/statusline-lib/render.sh
@@ -128,10 +128,10 @@ render_session() {
   # "main" so an understated number is never shown as if it were the total.
   if [ "$RANK" -ge 1 ]; then
     if [ -n "$cost_session" ]; then
-      cost_fmt=$(LC_NUMERIC=C awk "BEGIN{printf \"%.2f\",$cost_session}")
+      cost_fmt=$(LC_ALL=C awk -v v="${cost_session/,/.}" 'BEGIN{printf "%.2f", v+0}')
       line="${line:+$line ${SEP} }${KEY}session ${SUBTEXT}${DOLLAR}${cost_fmt}${RESET}"
     elif [ -n "$cost" ]; then
-      cost_fmt=$(LC_NUMERIC=C awk "BEGIN{printf \"%.2f\",$cost}")
+      cost_fmt=$(LC_ALL=C awk -v v="${cost/,/.}" 'BEGIN{printf "%.2f", v+0}')
       line="${line:+$line ${SEP} }${KEY}session main ${SUBTEXT}${DOLLAR}${cost_fmt}${RESET}"
     fi
   fi