fix: derive context percentage from remaining_percentage

The statusline showed a different percentage than Claude Code's native
"Context low (X% remaining)" message because used_percentage excludes
reserved overhead. Now uses 100 - remaining_percentage for alignment,
falling back to used_percentage for older versions.

Co-authored-by: Claude <noreply@anthropic.com>

Author: yepzdk

CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - `itkdev-statusline` extension with context window usage, git branch, and plan progress display
 
+### Fixed
+
+- Context percentage in `itkdev-statusline` now matches Claude Code's native context display by deriving from `remaining_percentage` instead of `used_percentage`
+
 ## [0.4.0] - 2026-02-20
 
 ### Added

extensions/itkdev-statusline/README.md

@@ -12,7 +12,7 @@ feat/auth │ 2/5 │ ▰▰▰▰▰▱▱▱▱▱ 45%
 |---------|--------|-------|
 | Git branch | `.git/HEAD` in `cwd` | Handles detached HEAD (short hash) |
 | Plan progress | `docs/plans/*.md` in `cwd` | Newest non-VERIFIED plan, checkbox counts |
-| Context % | stdin JSON `context_window.used_percentage` | 10-segment progress bar, color coded |
+| Context % | stdin JSON `context_window.remaining_percentage` | 10-segment progress bar, color coded. Falls back to `used_percentage`. |
 
 ### Context color thresholds
 

extensions/itkdev-statusline/bin/statusline.sh

@@ -1,13 +1,14 @@
 #!/usr/bin/env bash
 # itkdev-statusline: Claude Code statusline showing git branch, plan progress, and context usage.
-# Reads JSON from stdin (context_window.used_percentage, cwd).
+# Reads JSON from stdin (context_window.remaining_percentage, cwd).
 # Target: <30ms execution, no unnecessary subprocesses.
 
 set -euo pipefail
 
-# Parse cwd and used_percentage from stdin JSON via a single jq call.
-# Use parameter expansion to split on tab (read strips leading IFS chars).
-tsv=$(jq -r '[(.cwd // ""), (.context_window.used_percentage // 0), (.transcript_path // "")] | @tsv' 2>/dev/null) || true
+# Parse cwd and context percentage from stdin JSON via a single jq call.
+# Prefer remaining_percentage (matches Claude Code's native context display)
+# over used_percentage, which excludes reserved overhead and can differ.
+tsv=$(jq -r '[(.cwd // ""), (if (.context_window.remaining_percentage // null) != null then (100 - .context_window.remaining_percentage) | floor else (.context_window.used_percentage // 0) end), (.transcript_path // "")] | @tsv' 2>/dev/null) || true
 cwd="${tsv%%$'\t'*}"
 rest="${tsv#*$'\t'}"
 pct="${rest%%$'\t'*}"