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Model Switch History Tracker - Statuslines

Claude Code model switch detector tracking transitions between Opus/Sonnet/Haiku with switch count, current model indicator, and cost impact visualization.

by JSONbored·added 2025-10-25·

Claude Code

HarnessClaude Code

Language:bash

Install

Source

{
  "statusLine": {
    "type": "command",
    "command": "$CLAUDE_PROJECT_DIR/.claude/statuslines/model-switch-history-tracker.sh",
    "refreshInterval": 1000
  }
}

Readiness

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Open the source and read safety notes before installing.

Prerequisites

Claude Code CLI installed and configured
Bash shell available (bash 4.0+ recommended for case statements and string manipulation)
jq command-line JSON processor (jq 1.6+ recommended for safe extraction with // defaults)
date command with epoch timestamp support (date +%s for Unix timestamps)
Terminal with ANSI color code support (256-color mode recommended for color-coded model tiers)
Write access to home directory (~/.claude-code-model-history) for persistent model history files

Schema details

Install type: config
Reading time: 2 min
Difficulty score: 6
Troubleshooting: Yes
Breaking changes: No

Runtime and command metadata

Script language: bash

Script body

#!/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}"

Full copyable content

{
  "statusLine": {
    "type": "command",
    "command": "$CLAUDE_PROJECT_DIR/.claude/statuslines/model-switch-history-tracker.sh",
    "refreshInterval": 1000
  }
}

About this resource

Features

Real-time model detection for Opus, Sonnet, and Haiku variants
Switch count tracking showing total model changes in session
Last 3 switches mini-history showing transition patterns (Opus→Sonnet→Haiku)
Color-coded model tiers (magenta Opus, blue Sonnet, green Haiku)
Switch frequency warnings (green stable, yellow 1-3, red 4+ switches)
Persistent history storage per session in ~/.claude-code-model-history
Cost awareness through model tier visualization
Automatic switch event logging with timestamps

Use Cases

Cost optimization by tracking Opus vs Sonnet vs Haiku usage patterns
Identifying unnecessary model switching that inflates costs
Understanding which tasks require which model tier
Budget management through model tier awareness
Debugging unexpected model changes in Claude Code settings
Analyzing session patterns for optimal model selection strategy

Requirements

Claude Code CLI installed and configured
Bash shell available (bash 4.0+ recommended for case statements and string manipulation)
jq command-line JSON processor (jq 1.6+ recommended for safe extraction with // defaults)
date command with epoch timestamp support (date +%s for Unix timestamps)
Terminal with ANSI color code support (256-color mode recommended for color-coded model tiers)
Write access to home directory (~/.claude-code-model-history) for persistent model history files

Configuration

{
  "statusLine": {
    "type": "command",
    "command": "$CLAUDE_PROJECT_DIR/.claude/statuslines/model-switch-history-tracker.sh",
    "refreshInterval": 1000
  }
}

Examples

Enhanced Model Switch History Tracker with Cost Tracking

Extended version tracking cost impact of model switches

#!/usr/bin/env bash

# Enhanced Model Switch History Tracker with Cost Tracking

input=$(cat)

current_model=$(echo "$input" | jq -r '.model.display_name // .model.id // "unknown"')
session_id=$(echo "$input" | jq -r '.session_id // "unknown"')
total_cost=$(echo "$input" | jq -r '.cost.total_cost_usd // 0')

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

HISTORY_FILE="${HISTORY_DIR}/${session_id}.history"
COST_FILE="${HISTORY_DIR}/${session_id}.cost"

if [ ! -f "$HISTORY_FILE" ]; then
  echo "${current_model}" > "$HISTORY_FILE"
  echo "0" >> "$HISTORY_FILE"
fi

previous_model=$(sed -n '1p' "$HISTORY_FILE" 2>/dev/null || echo "")
switch_count=$(sed -n '2p' "$HISTORY_FILE" 2>/dev/null || echo "0")

if [ "$current_model" != "$previous_model" ] && [ -n "$previous_model" ] && [ "$previous_model" != "unknown" ]; then
  switch_count=$((switch_count + 1))
  echo "$(date +%s)|${previous_model}→${current_model}" >> "$HISTORY_FILE"

  # Track cost at switch point
  echo "$(date +%s)|${total_cost}" >> "$COST_FILE"
fi

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"

case "$current_model" in
  *"Opus"*|*"opus"*)
    MODEL_COLOR="\033[38;5;201m"
    MODEL_ICON="💎"
    MODEL_TIER="OPUS"
    ;;
  *"Sonnet"*|*"sonnet"*)
    MODEL_COLOR="\033[38;5;75m"
    MODEL_ICON="🎵"
    MODEL_TIER="SONNET"
    ;;
  *"Haiku"*|*"haiku"*)
    MODEL_COLOR="\033[38;5;46m"
    MODEL_ICON="🍃"
    MODEL_TIER="HAIKU"
    ;;
  *)
    MODEL_COLOR="\033[38;5;250m"
    MODEL_ICON="❓"
    MODEL_TIER="UNKNOWN"
    ;;
esac

if [ $switch_count -eq 0 ]; then
  SWITCH_STATUS="stable"
  SWITCH_COLOR="\033[38;5;46m"
elif [ $switch_count -le 3 ]; then
  SWITCH_STATUS="${switch_count} switches"
  SWITCH_COLOR="\033[38;5;226m"
else
  SWITCH_STATUS="${switch_count} switches!"
  SWITCH_COLOR="\033[38;5;196m"
fi

last_switches=$(tail -n 3 "$HISTORY_FILE" 2>/dev/null | grep '→' | cut -d'|' -f2 | tr '\n' ' ' | sed 's/ $//')
if [ -n "$last_switches" ]; then
  HISTORY_DISPLAY="| ${last_switches}"
else
  HISTORY_DISPLAY=""
fi

# Format cost
cost_formatted=$(printf "$%.2f" $total_cost 2>/dev/null || echo "$${total_cost}")

RESET="\033[0m"

echo -e "${MODEL_ICON} ${MODEL_COLOR}${MODEL_TIER}${RESET} | ${SWITCH_COLOR}${SWITCH_STATUS}${RESET} | $${cost_formatted} ${HISTORY_DISPLAY}"

Model Switch History Tracker with Extended Model Detection

Version with enhanced model name matching for all Claude variants

#!/usr/bin/env bash

# Model Switch History Tracker with Extended Model Detection

input=$(cat)

current_model=$(echo "$input" | jq -r '.model.display_name // .model.id // "unknown"')
session_id=$(echo "$input" | jq -r '.session_id // "unknown"')

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

HISTORY_FILE="${HISTORY_DIR}/${session_id}.history"

if [ ! -f "$HISTORY_FILE" ]; then
  echo "${current_model}" > "$HISTORY_FILE"
  echo "0" >> "$HISTORY_FILE"
fi

previous_model=$(sed -n '1p' "$HISTORY_FILE" 2>/dev/null || echo "")
switch_count=$(sed -n '2p' "$HISTORY_FILE" 2>/dev/null || echo "0")

if [ "$current_model" != "$previous_model" ] && [ -n "$previous_model" ] && [ "$previous_model" != "unknown" ]; then
  switch_count=$((switch_count + 1))
  echo "$(date +%s)|${previous_model}→${current_model}" >> "$HISTORY_FILE"
fi

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"

# Extended model detection (handles claude-3-5-sonnet, claude-opus-4-1, etc.)
case "$current_model" in
  *"Opus"*|*"opus"*|*"claude-opus"*|*"claude-4"*)
    MODEL_COLOR="\033[38;5;201m"
    MODEL_ICON="💎"
    MODEL_TIER="OPUS"
    ;;
  *"Sonnet"*|*"sonnet"*|*"claude-3-5"*|*"claude-3-7"*)
    MODEL_COLOR="\033[38;5;75m"
    MODEL_ICON="🎵"
    MODEL_TIER="SONNET"
    ;;
  *"Haiku"*|*"haiku"*|*"claude-3-haiku"*)
    MODEL_COLOR="\033[38;5;46m"
    MODEL_ICON="🍃"
    MODEL_TIER="HAIKU"
    ;;
  *)
    MODEL_COLOR="\033[38;5;250m"
    MODEL_ICON="❓"
    MODEL_TIER="UNKNOWN"
    ;;
esac

if [ $switch_count -eq 0 ]; then
  SWITCH_STATUS="stable"
  SWITCH_COLOR="\033[38;5;46m"
elif [ $switch_count -le 3 ]; then
  SWITCH_STATUS="${switch_count} switches"
  SWITCH_COLOR="\033[38;5;226m"
else
  SWITCH_STATUS="${switch_count} switches!"
  SWITCH_COLOR="\033[38;5;196m"
fi

last_switches=$(tail -n 3 "$HISTORY_FILE" 2>/dev/null | grep '→' | cut -d'|' -f2 | tr '\n' ' ' | sed 's/ $//')
if [ -n "$last_switches" ]; then
  HISTORY_DISPLAY="| ${last_switches}"
else
  HISTORY_DISPLAY=""
fi

RESET="\033[0m"

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

Model Switch History Tracker Installation Example

Complete setup script with history directory creation and Unicode character testing

#!/bin/bash
# Installation script for Model Switch History Tracker

# Check for jq (required for JSON parsing)
if ! command -v jq &> /dev/null; then
    echo "Installing jq for JSON parsing..."
    if [[ "$OSTYPE" == "darwin"* ]]; then
        brew install jq
    elif [[ "$OSTYPE" == "linux-gnu"* ]]; then
        sudo apt-get install -y jq || sudo yum install -y jq
    else
        echo "Please install jq manually: https://stedolan.github.io/jq/"
    fi
fi

# Create history directory
mkdir -p ~/.claude-code-model-history

echo "Model history directory created: ~/.claude-code-model-history"

# Test Unicode characters
if echo -e '💎 🎵 🍃 ❓ →' &> /dev/null; then
    echo "Unicode characters supported"
else
    echo "Warning: Unicode characters may not be supported in your terminal"
    echo "Arrow character (→) may display as '->' or box"
fi

# Test date command (required for timestamps)
if date +%s &> /dev/null; then
    echo "Date command working: $(date +%s)"
else
    echo "Warning: date command may not support +%s format"
fi

mkdir -p .claude/statuslines

cat > .claude/statuslines/model-switch-history-tracker.sh << 'SCRIPT_EOF'
#!/usr/bin/env bash

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

read -r input

current_model=$(echo "$input" | jq -r '.model.display_name // .model.id // "unknown"')
session_id=$(echo "$input" | jq -r '.session_id // "unknown"')

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

HISTORY_FILE="${HISTORY_DIR}/${session_id}.history"

if [ ! -f "$HISTORY_FILE" ]; then
  echo "${current_model}" > "$HISTORY_FILE"
  echo "0" >> "$HISTORY_FILE"
fi

previous_model=$(sed -n '1p' "$HISTORY_FILE" 2>/dev/null || echo "")
switch_count=$(sed -n '2p' "$HISTORY_FILE" 2>/dev/null || echo "0")

if [ "$current_model" != "$previous_model" ] && [ -n "$previous_model" ] && [ "$previous_model" != "unknown" ]; then
  switch_count=$((switch_count + 1))
  echo "$(date +%s)|${previous_model}→${current_model}" >> "$HISTORY_FILE"
fi

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"

case "$current_model" in
  *"Opus"*|*"opus"*)
    MODEL_COLOR="\033[38;5;201m"
    MODEL_ICON="💎"
    MODEL_TIER="OPUS"
    ;;
  *"Sonnet"*|*"sonnet"*)
    MODEL_COLOR="\033[38;5;75m"
    MODEL_ICON="🎵"
    MODEL_TIER="SONNET"
    ;;
  *"Haiku"*|*"haiku"*)
    MODEL_COLOR="\033[38;5;46m"
    MODEL_ICON="🍃"
    MODEL_TIER="HAIKU"
    ;;
  *)
    MODEL_COLOR="\033[38;5;250m"
    MODEL_ICON="❓"
    MODEL_TIER="UNKNOWN"
    ;;
esac

if [ $switch_count -eq 0 ]; then
  SWITCH_STATUS="stable"
  SWITCH_COLOR="\033[38;5;46m"
elif [ $switch_count -le 3 ]; then
  SWITCH_STATUS="${switch_count} switches"
  SWITCH_COLOR="\033[38;5;226m"
else
  SWITCH_STATUS="${switch_count} switches!"
  SWITCH_COLOR="\033[38;5;196m"
fi

last_switches=$(tail -n 3 "$HISTORY_FILE" 2>/dev/null | grep '→' | cut -d'|' -f2 | tr '\n' ' ' | sed 's/ $//')
if [ -n "$last_switches" ]; then
  HISTORY_DISPLAY="| ${last_switches}"
else
  HISTORY_DISPLAY=""
fi

RESET="\033[0m"

echo -e "${MODEL_ICON} ${MODEL_COLOR}${MODEL_TIER}${RESET} | ${SWITCH_COLOR}${SWITCH_STATUS}${RESET} ${HISTORY_DISPLAY}"
SCRIPT_EOF

chmod +x .claude/statuslines/model-switch-history-tracker.sh

# Add to settings.json
if [ ! -f .claude/settings.json ]; then
    echo '{"statusLine":{"type":"command","command":"$CLAUDE_PROJECT_DIR/.claude/statuslines/model-switch-history-tracker.sh","refreshInterval":1000}}' > .claude/settings.json
else
    jq '.statusLine = {"type":"command","command":"$CLAUDE_PROJECT_DIR/.claude/statuslines/model-switch-history-tracker.sh","refreshInterval":1000}' .claude/settings.json > .claude/settings.json.tmp
    mv .claude/settings.json.tmp .claude/settings.json
fi

echo "Model Switch History Tracker installed successfully!"
echo "Note: History files stored in ~/.claude-code-model-history/"
echo "View history: cat ~/.claude-code-model-history/[session-id].history"

Troubleshooting

Model always showing UNKNOWN despite valid Claude model running

Check model.display_name field: echo '$input' | jq .model.display_name. Script matches case-insensitively on 'Opus', 'Sonnet', 'Haiku' keywords. If model name doesn't contain these (e.g., 'claude-3-5-sonnet-20241022'), add custom matching: 'claude-3-5-sonnet') MODEL_TIER='SONNET'. Verify field exists and has expected format. Check model.id as fallback: echo '$input' | jq .model.id.

Switch count not incrementing when changing models

Verify session_id is consistent: echo '$input' | jq .session_id. Each session has separate history file. If session_id changes, switch count resets (expected). Check history file exists: ls ~/.claude-code-model-history/${session_id}.history. Verify file format: first line = current model, second line = switch count. Manually test: echo 'Opus' > file.history && echo '0' >> file.history. Check model comparison logic: ensure previous_model is not empty.

Permission denied when creating model history directory

Ensure HOME environment variable is set: echo $HOME. Check write permissions: mkdir -p ~/.claude-code-model-history. If permission denied, change location: HISTORY_DIR='/tmp/claude-model-history-$(whoami)'. Verify statusline script runs with correct user permissions. Check disk space: df -h ~. Verify directory creation: mkdir -p ~/.claude-code-model-history && touch ~/.claude-code-model-history/test && rm ~/.claude-code-model-history/test.

Last 3 switches history not displaying transitions

History format is 'timestamp|ModelA→ModelB' (e.g., '1730000000|Opus→Sonnet'). Check file content: tail ~/.claude-code-model-history/${session_id}.history. Grep filter looks for '→' character - ensure terminal encoding supports Unicode arrow. Alternative: replace → with ASCII '->' in script. Verify grep works: echo 'test→test' | grep '→'. Check cut command: echo '123|Opus→Sonnet' | cut -d'|' -f2 (should return 'Opus→Sonnet').

Switch frequency showing incorrect count

Switch count stored on line 2 of history file. Verify: sed -n '2p' ~/.claude-code-model-history/${session_id}.history. Count only increments when current_model != previous_model AND previous_model is not empty. New sessions start at 0 (expected). Manually reset: echo '0' to line 2 if corrupted. Check arithmetic: switch_count=$((switch_count + 1)). Verify sed reading: sed -n '2p' file.history (should return number).

History file corruption or invalid format

Verify file format: first line = current model, second line = switch count, subsequent lines = switch events. Check file exists and is readable: ls -l ~/.claude-code-model-history/${session_id}.history. Verify sed commands work: sed -n '1p' file (first line), sed -n '2p' file (second line). Check temp file operations: ensure temp_file is created and moved atomically. If corrupted, delete history file to reset: rm ~/.claude-code-model-history/${session_id}.history.

Unicode arrow character (→) not displaying correctly

Verify terminal encoding supports Unicode: locale charmap (should be UTF-8). Set terminal to UTF-8: export LANG=en_US.UTF-8. Test arrow: echo -e '→'. If not supported, modify script to use ASCII '->' instead. Check grep for arrow: echo 'test→test' | grep '→' (should match). Verify tr and sed handle Unicode: echo '→' | tr '→' '->'.

Model switch detection not working for new model variants

Script uses case-insensitive pattern matching on 'Opus', 'Sonnet', 'Haiku'. For new variants (e.g., 'claude-3-5-sonnet-20241022'), extend case statement: 'claude-3-5') MODEL_TIER='SONNET'. Check model name format: echo '$input' | jq .model.display_name. Add custom patterns for specific model IDs. Verify case statement syntax: case "$current_model" in pattern) commands ;; esac.

Content outline

Features
Use Cases
Requirements
Configuration
Examples
Enhanced Model Switch History Tracker with Cost Tracking
Model Switch History Tracker with Extended Model Detection
Model Switch History Tracker Installation Example
Troubleshooting
Model always showing UNKNOWN despite valid Claude model running
Switch count not incrementing when changing models
Permission denied when creating model history directory
Last 3 switches history not displaying transitions
Switch frequency showing incorrect count
History file corruption or invalid format
Unicode arrow character (→) not displaying correctly

#model-switching#opus-sonnet-haiku#cost-optimization#model-tracking#switch-history

Source citations

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