fix: adjust bubble tail calculation to account for leading space in render script and tests

Author: TimJJTing

lib/render.sh

@@ -44,9 +44,10 @@ for l in "${LINES[@]+"${LINES[@]}"}"; do
 done
 
 # Bubble tail ┬ lands at the center of the center column (0-indexed TAIL_COL).
-# Formula: CHAR_SIDE_WIDTH + CHAR_CENTER_WIDTH/2. Default 5+4=9 → LEFT_DASHES=8.
+# Formula: CHAR_SIDE_WIDTH + CHAR_CENTER_WIDTH/2. Default 5+4=9 → LEFT_DASHES=7.
+# Bubble lines have a leading space before ╰, so LEFT_DASHES = TAIL_COL - 2.
 _TAIL_COL=$(( ${CHAR_SIDE_WIDTH:-5} + (${CHAR_CENTER_WIDTH:-8} / 2) ))
-_LEFT_DASHES=$(( _TAIL_COL - 1 ))
+_LEFT_DASHES=$(( _TAIL_COL - 2 ))
 _MIN_INNER=$(( _LEFT_DASHES + 2 ))  # guarantees at least 1 dash right of junction
 INNER=$(( MAX + 2 < _MIN_INNER ? _MIN_INNER : MAX + 2 ))
 TOP_BORDER=$(printf '─%.0s' $(seq 1 $INNER))

tests/test-render.sh

@@ -14,7 +14,7 @@ render() { bash "$PLUGIN_ROOT/lib/render.sh" "$@"; }
 
 # Compute expected bubble tail strings from dimension vars.
 _tail_col=$(( ${CHAR_SIDE_WIDTH:-5} + (${CHAR_CENTER_WIDTH:-8} / 2) ))
-_left_dashes=$(( _tail_col - 1 ))
+_left_dashes=$(( _tail_col - 2 ))
 _left_str=$(printf '─%.0s' $(seq 1 $_left_dashes))
 _expected_tail="╰${_left_str}┬"
 _expected_short_bottom="╰${_left_str}┬─╯"