Session Persistence in Claude Code

Overview

Claude Code provides sophisticated session persistence that goes beyond simple conversation history. It maintains complete development environment state including background processes, file contexts, permissions, and working directories.

Session Commands

Core Commands

What Gets Persisted

1. Conversation History

• Full message history between user and Claude
• Tool call records with parameters and responses
• Context from previous interactions
• File references and modifications

2. Background Processes

Background tasks started with run_in_background: true persist across sessions:

# Example: Server started in one session
python3 -m http.server 8080  # bash_3

# After --continue or --resume:
# - Process still running
# - Shell ID preserved (bash_3)
# - Can check output with BashOutput tool
# - Can kill with KillBash tool

Verified Test Results:

• Background processes continue running after session ends
• Shell IDs (bash_1, bash_2, etc.) are preserved
• Output buffers maintained for incremental reading
• Process state tracked (running/completed/killed)

3. File Context

Claude remembers which files have been accessed:

# Files read with Read tool
# Files edited with Edit tool
# Files created with Write tool
# All remembered across sessions

Test Example:

# Session 1: Create a marker file
claude> Write test-session-marker.txt

# Session 2: Claude knows about the file without re-reading
claude --continue
claude> "What's in test-session-marker.txt?"
# Claude can reference it from memory

4. Working Directory Context

# Current working directory preserved
# Environment state maintained
# Path contexts remembered

5. Tool Permissions

Permissions granted in one session carry over:

# First session: Approve Bash tool for git commands
# Subsequent sessions: No re-approval needed for same patterns

Incremental Output Tracking

The BashOutput tool maintains read positions:

# First check of bash_6
BashOutput(bash_6) → Shows lines 1-10

# Second check (even after session resume)
BashOutput(bash_6) → Shows only NEW lines 11-20

# Prevents duplicate output display

Session Storage

Location

Sessions are stored locally on the machine (exact path varies by OS):

• Likely in ~/.config/claude/ or similar
• Each session has a unique identifier
• Automatic cleanup of old sessions

Session Structure

{
  "sessionId": "abc123-def456",
  "startTime": "2025-08-11T22:00:00Z",
  "lastActive": "2025-08-11T22:27:00Z",
  "messages": [...],
  "backgroundTasks": {
    "bash_3": {
      "command": "python3 -m http.server 8080",
      "status": "running",
      "pid": 295416,
      "outputPosition": 1234
    }
  },
  "fileContext": {
    "read": ["file1.txt", "file2.js"],
    "modified": ["config.json"],
    "created": ["test-marker.txt"]
  },
  "permissions": {
    "approvedTools": ["Bash(git:*)", "Edit"],
    "directories": ["/workspaces/project"]
  }
}

Practical Examples

Example 1: Development Server Management

# Monday: Start development
claude
> Start npm run dev in background
> Start docker-compose up in background
> Work on features...
> Exit (servers keep running)

# Tuesday: Continue work
claude --continue
> Check status of npm run dev  # Still running!
> Show docker logs  # Can see all output
> Continue development...

Example 2: Long-Running Build

# Start a long build
claude
> Run build script in background
> Exit for lunch

# Return and check progress
claude --continue
> Check build output  # See what happened while away
> Build completed? Check exit code

Example 3: Debug Session

# Complex debugging session
claude
> Set up monitoring in background
> Create test files
> Run diagnostics
> [System crash/need to leave]

# Resume exactly where left off
claude --resume
> All background monitors still running
> Test files still in context
> Continue debugging from exact point

Best Practices

1. Session Management

DO:

• Use --continue for same-day work continuity
• Use --resume when you need a specific past session
• Name sessions meaningfully with --session-id
• Clean up background tasks before extended breaks

DON'T:

• Leave unnecessary background tasks running for days
• Rely on sessions older than a week (may be cleaned up)
• Assume background processes survive system reboots

2. Background Task Management

# Before ending a session, check background tasks
/bashes  # List all background tasks

# Clean up if needed
"Kill all background tasks except the dev server"

# Or selectively
"Kill bash_1 and bash_2 but keep bash_3"

3. Context Preservation

# Create a session marker for complex work
"Create SESSION_NOTES.md with current context"

# Helps both you and Claude remember the context
"Update SESSION_NOTES.md with progress"

Limitations

1. System Boundaries

• Sessions are local to the machine
• Don't survive system reboots
• Can't transfer between machines

2. Process Limitations

• Background processes may be killed by OS for resources
• Very long-idle processes may timeout
• Output buffers have size limits

3. Security Boundaries

• File permissions re-checked on resume
• New sensitive operations require re-approval
• Directory access validated each session

Advanced Features

Session Branching

You can resume the same session multiple times:

# Original work
claude --session-id project-main

# Branch 1: Try approach A
claude --resume project-main
# Work on approach A

# Branch 2: Try approach B  
claude --resume project-main
# Work on approach B
# Both branches have the same starting context

Partial Recovery

Even if a session is partially corrupted:

• Conversation history usually recoverable
• File context often intact
• Background tasks may need restart

Auto-Cleanup

Claude Code automatically manages sessions:

• Old sessions pruned after time limit
• Configurable retention period
• Automatic compression for large sessions

Troubleshooting

Issue: Background task not found after resume

# Check if process still exists
ps aux | grep <command>

# If process died, restart it
"Restart the dev server that was in bash_3"

Issue: Session won't resume

# Try continue instead
claude --continue

# List recent sessions
claude --resume  # Interactive selection

# Start fresh if needed
claude  # New session

Issue: Permissions not remembered

# Permissions may expire for security
# Simply re-approve when prompted
# Or use --dangerously-skip-permissions for development

Verification Tests

The following features have been tested and verified:

✅ Background Task Persistence

• Started python3 -m http.server 8080 as bash_3
• Session continued, server still running
• Process verified with ps aux

✅ Shell ID Preservation

• Background task IDs (bash_1, bash_2, etc.) maintained
• Can reference same IDs after resume

✅ Incremental Output

• BashOutput only returns new output since last check
• Position markers maintained across sessions

✅ File Context Memory

• Files created/edited in session remembered
• No need to re-read files after resume

✅ Multiple Background Tasks

• Can run multiple background processes
• All tracked independently
• Each maintains its own state

Related Documentation

• Background Commands Guide
• Claude Code CLI Reference
• MCP Tools Documentation

Last updated: August 2025 Verified with Claude Code latest version