feat(statusline): show context-window usage % in the status line

Adds .claude/statusline.sh (reads context_window.used_percentage +
context_window_size straight from the statusLine JSON; green<70/yellow/red
bar) and wires it via .claude/settings.json statusLine. Committed in-repo so
it follows boma to any clone, matching how .claude/ already tracks hooks +
plugins.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude/settings.json

@@ -69,5 +69,10 @@
         ]
       }
     ]
+  },
+  "statusLine": {
+    "type": "command",
+    "command": "bash \"${CLAUDE_PROJECT_DIR:-.}/.claude/statusline.sh\"",
+    "padding": 0
   }
 }

.claude/statusline.sh

@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+#
+# Claude Code statusLine — shows working dir, model, and context-window usage.
+# Wired via .claude/settings.json (statusLine.command). Receives the statusLine
+# JSON on stdin; first stdout line is rendered (ANSI colour supported).
+#
+# Context usage comes straight from the input JSON — no transcript parsing:
+#   .context_window.used_percentage     pre-calculated % of the window in use (input side)
+#   .context_window.context_window_size window size in tokens (1000000 for the 1M models)
+# verified: Claude Code statusLine schema · code.claude.com/docs/en/statusline · 2026-06-17
+#
+# Fails soft: any parse problem prints nothing and exits 0 (never breaks the prompt).
+set -uo pipefail
+
+input=$(cat 2>/dev/null) || exit 0
+command -v jq >/dev/null 2>&1 || exit 0
+
+# pct<TAB>window<TAB>dir-basename<TAB>model-name  (used_percentage preferred,
+# else derived from current_usage, else 0). @tsv keeps spaces in the dir safe.
+parsed=$(printf '%s' "$input" | jq -r '
+  (.workspace.current_dir // .cwd // "" | sub(".*/"; "")) as $dir
+  | (.model.display_name // "?")                          as $model
+  | (.context_window.context_window_size // 200000)       as $win
+  | (
+      if (.context_window.used_percentage // null) != null then
+        .context_window.used_percentage
+      elif (.context_window.current_usage // null) != null then
+        ((.context_window.current_usage.input_tokens
+          + (.context_window.current_usage.cache_creation_input_tokens // 0)
+          + (.context_window.current_usage.cache_read_input_tokens // 0)) / $win * 100)
+      else 0 end | floor
+    ) as $pct
+  | [$pct, $win, $dir, $model] | @tsv
+' 2>/dev/null) || exit 0
+[ -z "$parsed" ] && exit 0
+
+IFS=$'\t' read -r pct win dir model <<<"$parsed"
+
+# Human window label: 1000000 -> 1M, 200000 -> 200k, else Nk.
+case "$win" in
+  1000000) wlabel="1M" ;;
+  *)       wlabel="$((win / 1000))k" ;;
+esac
+
+# Colour the bar/percentage by pressure: green <70, yellow 70–89, red >=90.
+if   [ "$pct" -ge 90 ]; then col=$'\033[31m'   # red
+elif [ "$pct" -ge 70 ]; then col=$'\033[33m'   # yellow
+else                        col=$'\033[32m'    # green
+fi
+dim=$'\033[2m'; rst=$'\033[0m'
+
+# 10-cell bar; clamp fill to [0,10] so an over-100 reading can't overflow.
+filled=$((pct / 10)); [ "$filled" -gt 10 ] && filled=10; [ "$filled" -lt 0 ] && filled=0
+bar=""
+for ((i = 0; i < 10; i++)); do
+  if [ "$i" -lt "$filled" ]; then bar+="█"; else bar+="░"; fi
+done
+
+printf '%s%s%s · %s · %s%s %d%%%s %sctx/%s%s\n' \
+  "$dim" "$dir" "$rst" \
+  "$model" \
+  "$col" "$bar" "$pct" "$rst" \
+  "$dim" "$wlabel" "$rst"