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Concurrent Sessions

Run multiple Claude CLI instances simultaneously. Different account profiles normally use different Claude config directories, while launching the same profile twice reuses the same directory and shared state.

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Overview

# Terminal 1
ccs work "implement feature X"

# Terminal 2 (simultaneously)
ccs personal "research topic Y"

# Different profiles = separate default state

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Architecture

CCS uses CLAUDE_CONFIG_DIR to select the Claude config directory for each account profile: 
~/.ccs/instances/work/        # Work account
~/.ccs/instances/personal/    # Personal account
When you run ccs work "task":
  1. Sets CLAUDE_CONFIG_DIR=~/.ccs/instances/work/
  2. Claude loads credentials from that directory
  3. That session reuses the work profile’s state directory
That gives you a simple rule of thumb:
  • Different profiles such as work and personal normally use different directories
  • The same profile such as work + work reuses one directory
  • If you configure continuity inheritance, different profile names can intentionally reuse the same directory too

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Instance Structure

Each account profile gets its own default directory: 
~/.ccs/instances/work/
├── .anthropic/           # Claude-managed metadata
├── session-env/           # Chat history
├── todos/                 # Task lists
├── logs/                  # Execution logs
├── file-history/          # Recent file context
├── shell-snapshots/       # Shell continuity artifacts
├── debug/                 # Debug artifacts
├── commands/              # Shared link/copy in non-bare profiles
└── skills/                # Shared link/copy in non-bare profiles

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Performance

MetricFirst UseSubsequent
Activation~20-35ms~5-10ms
Memory~3-5 KB per activation-
Disk~200-700 KB per profile-

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Limitations

Running the same profile in multiple terminals is allowed, but both terminals reuse the same CLAUDE_CONFIG_DIR and shared state. Use different profiles when you want stronger separation.
# Shared state on purpose:
ccs work "task1"  # Terminal 1
ccs work "task2"  # Terminal 2 - same profile, same state directory

# Separate state:
ccs work "task1"      # Terminal 1
ccs personal "task2"  # Terminal 2
This is not a special CCS-only restriction. Any two launches that point at the same Claude config directory share mutable state.

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Other Limitations

  • CLAUDE_CONFIG_DIR is undocumented (keep Claude CLI updated)
  • Same-profile launches share history, todos, logs, and other mutable artifacts
  • Non-bare profiles share commands, skills, agents, plugins, and settings.json via ~/.ccs/shared/
  • Sessions/logs accumulate (manual cleanup if needed)

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Shared Resources

By default, non-bare account profiles reuse the shared CCS layout for commands, skills, agents, plugins, and settings.json. 
# Recreate shared symlinks after changing shared resources
ccs sync
If you created a profile with --bare, it opts out of that shared layout on purpose.

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Cleanup

# Check sizes
du -sh ~/.ccs/instances/*

# Clear sessions
rm -rf ~/.ccs/instances/work/session-env/*

# Clear logs
rm -rf ~/.ccs/instances/work/logs/*