From fb057b3b05f4a7c4178d545bacd8be425ec242e4 Mon Sep 17 00:00:00 2001
From: Klaus Agnoletti <klag@cybertechservices.dk>
Date: Wed, 17 Jun 2026 14:20:57 +0200
Subject: [PATCH] fix(statusline): correct context percentage when switching
 models mid-session
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When a Claude Code session starts with Opus (1M context window) and the user
switches to Sonnet/Haiku (200K window) — or vice versa — the statusline may
display an incorrect context percentage. Claude Code's context_window_size JSON
field can reflect the session's starting model rather than the currently active
model.

Root cause: used_percentage is calculated by Claude Code against context_window_size
from session start. After a model switch, the denominator is wrong.

Fix: derive the expected context window from model_name (which IS current), then
recalculate context_pct using total_input_tokens (absolute, model-independent)
against the correct window. Falls back to proportional rescaling if total_input
is unavailable. No-op when context_max already matches the model's expected size.

Model→window mapping:
  Opus 4.x     → 1,048,576 tokens
  Sonnet 4.x   → 200,000 tokens
  Haiku 4.x    → 200,000 tokens
  Fable        → 200,000 tokens
  Unknown      → no correction (display as-is)
---
 Releases/v4.0.3/.claude/statusline-command.sh | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Releases/v4.0.3/.claude/statusline-command.sh b/Releases/v4.0.3/.claude/statusline-command.sh
index eba866cafe..5782835f01 100755
--- a/Releases/v4.0.3/.claude/statusline-command.sh
+++ b/Releases/v4.0.3/.claude/statusline-command.sh
@@ -100,6 +100,27 @@ context_remaining=${context_remaining:-100}
 total_input=${total_input:-0}
 total_output=${total_output:-0}
 
+# Model-aware context window correction. When switching between Opus (1M) and
+# Sonnet/Haiku (200K) mid-session, Claude Code may report context_window_size
+# from the session's starting model, not the current model. Use model_name to
+# derive the expected window and recalculate context_pct against the right value.
+_model_lower="${model_name,,}"
+if [[ "$_model_lower" == *"opus"* ]]; then
+    _expected_ctx=1048576
+elif [[ "$_model_lower" == *"sonnet"* ]] || [[ "$_model_lower" == *"haiku"* ]] || [[ "$_model_lower" == *"fable"* ]]; then
+    _expected_ctx=200000
+else
+    _expected_ctx=""
+fi
+if [ -n "$_expected_ctx" ] && [ "$context_max" != "$_expected_ctx" ] && [ "$_expected_ctx" -gt 0 ]; then
+    if [ "$total_input" -gt 0 ]; then
+        context_pct=$(( total_input * 100 / _expected_ctx ))
+    elif [ "$context_max" -gt 0 ] && [ "$context_pct" -gt 0 ]; then
+        context_pct=$(( context_pct * context_max / _expected_ctx ))
+    fi
+    context_max="$_expected_ctx"
+fi
+
 # NOTE: Removed fallback that calculated context_pct from total_input + total_output
 # when used_percentage was 0. total_input/output_tokens are CUMULATIVE session totals
 # (like an odometer) — they can far exceed context_window_size. After /clear,