Model Switch History Tracker

#!/usr/bin/env bash

# Model Switch History Tracker for Claude Code
# Tracks transitions between Claude models (Opus, Sonnet, Haiku)

# Read JSON from stdin
read -r input

# Extract current model info
current_model=$(echo "$input" | jq -r '.model.display_name // "unknown"')
session_id=$(echo "$input" | jq -r '.session_id // "unknown"')

# Model history tracking directory
HISTORY_DIR="${HOME}/.claude-code-model-history"
mkdir -p "$HISTORY_DIR"

# Session-specific history file
HISTORY_FILE="${HISTORY_DIR}/${session_id}.history"

# Initialize history file if doesn't exist
if [ ! -f "$HISTORY_FILE" ]; then
  echo "${current_model}" > "$HISTORY_FILE"
  echo "0" >> "$HISTORY_FILE"  # Switch count
fi

# Read previous model and switch count
previous_model=$(sed -n '1p' "$HISTORY_FILE")
switch_count=$(sed -n '2p' "$HISTORY_FILE")

# Detect model switch
if [ "$current_model" != "$previous_model" ] && [ "$previous_model" != "" ]; then
  # Model changed - increment switch count
  switch_count=$((switch_count + 1))
  
  # Log switch event (append to history)
  echo "$(date +%s)|${previous_model}→${current_model}" >> "$HISTORY_FILE"
fi

# Update current model and switch count (overwrite first 2 lines)
temp_file="${HISTORY_FILE}.tmp"
echo "${current_model}" > "$temp_file"
echo "${switch_count}" >> "$temp_file"
tail -n +3 "$HISTORY_FILE" >> "$temp_file" 2>/dev/null
mv "$temp_file" "$HISTORY_FILE"

# Determine model tier and color
case "$current_model" in
  *"Opus"*|*"opus"*)
    MODEL_COLOR="\033[38;5;201m"  # Magenta: Opus (most expensive)
    MODEL_ICON="💎"
    MODEL_TIER="OPUS"
    ;;
  *"Sonnet"*|*"sonnet"*)
    MODEL_COLOR="\033[38;5;75m"   # Blue: Sonnet (balanced)
    MODEL_ICON="🎵"
    MODEL_TIER="SONNET"
    ;;
  *"Haiku"*|*"haiku"*)
    MODEL_COLOR="\033[38;5;46m"   # Green: Haiku (cheapest)
    MODEL_ICON="🍃"
    MODEL_TIER="HAIKU"
    ;;
  *)
    MODEL_COLOR="\033[38;5;250m"  # Gray: Unknown
    MODEL_ICON="❓"
    MODEL_TIER="UNKNOWN"
    ;;
esac

# Switch frequency indicator
if [ $switch_count -eq 0 ]; then
  SWITCH_STATUS="stable"
  SWITCH_COLOR="\033[38;5;46m"   # Green: No switches
elif [ $switch_count -le 3 ]; then
  SWITCH_STATUS="${switch_count} switches"
  SWITCH_COLOR="\033[38;5;226m"  # Yellow: 1-3 switches
else
  SWITCH_STATUS="${switch_count} switches!"
  SWITCH_COLOR="\033[38;5;196m"  # Red: 4+ switches (frequent switching)
fi

# Get last 3 switches for mini-history
last_switches=$(tail -n 3 "$HISTORY_FILE" | grep '→' | cut -d'|' -f2 | tr '\n' ' ' | sed 's/ $//')
if [ -n "$last_switches" ]; then
  HISTORY_DISPLAY="| ${last_switches}"
else
  HISTORY_DISPLAY=""
fi

RESET="\033[0m"

# Output statusline
echo -e "${MODEL_ICON} ${MODEL_COLOR}${MODEL_TIER}${RESET} | ${SWITCH_COLOR}${SWITCH_STATUS}${RESET} ${HISTORY_DISPLAY}"

{
  "format": "bash",
  "position": "left",
  "refreshInterval": 1000
}