Claude Code Context Management

Complete guide to managing context window, compression, and conversation flow.

Context Window Overview

Claude Code manages a conversation context window that accumulates messages, tool calls, and results throughout a session.

Context Limits

• The context window has a fixed token limit based on the model
• Claude Code automatically warns when approaching limits
• Auto-compact triggers when threshold is reached (configurable)

Configuration

// settings.json
{
  "autoCompact": true,
  "contextWindow": {
    "compactThreshold": 0.8,
    "warningThreshold": 0.9
  }
}

Context Reduction Strategies

1. /compact Command

/compact                         # General compression
/compact focus on authentication # Preserve auth-related context

What gets preserved:

• Key decisions and conclusions
• File paths and structure discoveries
• Error patterns and fixes
• Current task state

What gets summarized/dropped:

• Verbose tool outputs
• Intermediate search results
• Exploratory code reads
• Redundant conversation turns

2. /clear Command

/clear

Complete reset — use between unrelated tasks.

3. Sub-agents for Research

Offload research to sub-agents to keep main context clean:

// Instead of reading 20 files in main context:
Agent(subagent_type="Explore", prompt="Find all API endpoint definitions")

// The agent researches and returns a summary
// Main context only gets the summary, not all file contents

4. Targeted File Reads

// Bad: Read entire large file
Read(file_path="/path/to/large-file.ts")

// Good: Read specific section
Read(file_path="/path/to/large-file.ts", offset=100, limit=50)

// Good: Search first, then read specific matches
Grep(pattern="function authenticate", path="/path/to/")

5. Background Tasks

Long-running operations in background don't consume main context:

Agent(run_in_background=true, ...)
Bash(command="npm test", run_in_background=true)

Context Consumption by Tool

High Context Consumers

Tool	Context Impact	Mitigation
Read (large files)	Very High	Use offset/limit
Bash (verbose output)	High	Pipe through head/tail
Grep (many matches)	High	Use head_limit
Agent (results)	Medium-High	Agent summarizes internally

Low Context Consumers

Tool	Context Impact
Glob	Low (just file paths)
Write	Low (content sent, not echoed back)
Edit	Low (just the diff)
TodoWrite	Very Low
AskUserQuestion	Very Low

Conversation Flow Patterns

Focused Session

1. /clear (fresh start)
2. State the objective clearly
3. Claude researches and plans
4. Claude implements
5. Claude tests
6. Session ends

Long Session with Multiple Tasks

1. Task A work
2. /compact (preserve Task A context)
3. Task B work
4. /compact (preserve A+B context)
5. Task C work
6. ...

Research-Heavy Session

1. Spawn research agents (background)
2. Work on other tasks while agents research
3. Agents return summaries
4. Synthesize findings
5. Implement based on research

Auto-Memory

Claude Code can automatically save important context across sessions:

What Gets Saved

• Project structure discoveries
• User preferences
• Recurring patterns
• Key file paths
• Configuration details

Memory Location

• ~/.claude/projects/<project>/memory/MEMORY.md — Auto-loaded
• Additional topic files in same directory

Controlling Auto-Memory

# Disable auto-memory
export DISABLE_AUTOMEMORY=1

# Or in settings.json
{ "autoMemory": false }

Manual Memory Commands

/memory              # View current memories
/memory add <text>   # Add memory entry
/memory clear        # Clear all memories

# In conversation
"Remember that we always use pnpm, not npm"
"Forget the previous instruction about yarn"

Token Usage Tracking

/cost Command

Shows current session costs:

/cost

Output includes:

• Input tokens used
• Output tokens used
• Cache read/write tokens
• Estimated cost in USD

Reducing Costs

1. Use /compact to reduce repeated context
2. Use sub-agents for exploration
3. Use claude-haiku-4-5 for simple tasks (/model claude-haiku-4-5-20251001)
4. Use targeted reads instead of full file reads
5. Use Grep to find specific content instead of reading everything

Session Management

Continue Previous Session

# Resume last conversation
claude --continue
claude -c

# Resume specific session
claude --resume <session-id>

Session ID

# Set specific session ID
claude --session-id my-session-123

Conversation ID

# Set conversation ID within session
claude --conversation-id conv-456

Best Practices

1. Start focused — State your objective clearly upfront
2. Compact regularly — Don't wait for auto-compact
3. Use sub-agents — Keep research out of main context
4. Read selectively — Use offset/limit for large files
5. Clear between tasks — /clear for unrelated work
6. Track costs — Use /cost periodically
7. Leverage memory — Save important discoveries for future sessions
8. Background long tasks — Use run_in_background for slow operations