Claude Code context window: what happens when you hit the limit and how to avoid it

You're deep in a complex debugging session. Claude has been helping you trace a nasty bug through 12 files. Then it starts giving weird answers. It forgets things you just told it. Suggestions stop making sense.

You've hit the context window limit — and most developers don't realize it until things go sideways.

Here's exactly what happens and how to stay ahead of it.

What the context window actually is

Claude Code holds your entire conversation — prompts, responses, file contents, command outputs — in a single context window. Claude 3.7 Sonnet has a 200,000 token context window. That sounds huge. In practice, a medium codebase session can burn through it in 30-45 minutes of active work.

Tokens consumed by:

• Every message you send
• Every response Claude gives
• Every file Claude reads with cat or read_file
• Every command output (stack traces, test results, logs)
• Your CLAUDE.md file (loaded at session start)

Warning signs you're approaching the limit

Claude starts hedging on things it knew before:

You: Remember the UserService we refactored earlier?
Claude: I don't have full context on the UserService. Could you share the relevant code?

Responses get shorter and less specific:
Instead of writing the actual fix, Claude starts saying "you'll want to update the function to handle this case."

It contradicts itself:
Suggests an approach you already tried, or forgets a constraint you established 20 minutes ago.

The /cost command shows high token usage:

> /cost
Tokens used: 180,432 / 200,000
Cost this session: $0.54

The nuclear option: just let it happen

When Claude Code hits the limit, it starts a new context. Everything before is gone. This is like deleting your working memory mid-surgery.

Don't let it happen by accident.

Strategy 1: Checkpoint summaries

Every 45 minutes (or after completing a major task), ask Claude to write a checkpoint:

Write a concise checkpoint of this session to CHECKPOINT.md:
- What we were trying to accomplish
- What we've completed
- Current state of each file we've touched
- Unresolved issues and next steps
- Key decisions we made and why

Then at the start of a new session:

Read CHECKPOINT.md and continue from where we left off.

Strategy 2: Keep CLAUDE.md tight

Your CLAUDE.md loads at every session start, consuming tokens before you type anything. Keep it under 500 lines. The goal is context, not documentation:

# Project: PaymentService

## Architecture
- Node.js API, PostgreSQL, Redis for sessions
- Services in /src/services/, routes in /src/routes/

## Current focus
- Refactoring payment flow to use idempotency keys
- Issue: duplicate charges on network timeout

## DO NOT
- Touch legacy /src/legacy/ — it's frozen
- Change the Stripe webhook signature verification

That's it. Don't put your entire README in there.

Strategy 3: Scope your file reads

Instead of:

Read all the files in /src/services/

Do:

Read only src/services/PaymentService.js and src/services/WebhookService.js

Each file read costs tokens proportional to file size. A 500-line file is ~2,000 tokens. Reading 10 files to find one bug = 20,000 tokens gone before you start.

Strategy 4: Compress command output

Long stack traces and test output bloat your context fast. Pipe long output through tail or grep:

# Instead of letting Claude run:
npm test

# Tell Claude to run:
npm test 2>&1 | tail -50

# Or for specific failures:
npm test 2>&1 | grep -A 5 'FAIL\|Error'

This can cut context consumption by 80% on test-heavy workflows.

Strategy 5: Fresh context for fresh problems

When you switch from one feature to a completely different one, start a new Claude Code session. Don't carry baggage from the previous context.

The checkpoint from the previous session has everything you need to restore state in 30 seconds.

Strategy 6: The /compact command

Claude Code has a built-in /compact slash command that summarizes the conversation so far, replacing verbose history with a dense summary:

> /compact
Compacting conversation history...
Tokens before: 145,200
Tokens after: 28,400

Run it after completing a major chunk of work. You lose some detail but keep the essential context at a fraction of the token cost.

The rate limit connection

Here's something developers miss: context window management and rate limits are related problems.

When you have a large context, every request sends that full context to the API. A 150,000 token context means every single message is a massive API call — which hits your rate limits faster and costs more.

Keeping your context lean isn't just about staying under the window limit. It's about making every token of your budget go further.

If you're hitting rate limits frequently, a hosted API proxy like SimplyLouie gives you a stable ANTHROPIC_BASE_URL endpoint — useful when you're running parallel agents or long sessions that need consistent throughput at $2/month.

Quick reference

Situation	Action
45 min into session	Write checkpoint, consider /compact
Switching features	New session, load checkpoint
Long test output	Pipe through tail -50 or grep
CLAUDE.md > 500 lines	Trim to essentials
Starting fresh	Check for CHECKPOINT.md
Context > 150k tokens	Run /compact immediately

The session lifecycle that actually works

1. Start session → Claude reads CLAUDE.md (lean, ~200 lines)
2. Load checkpoint → "Read CHECKPOINT.md and continue"
3. Work in focused scope → one feature or one bug at a time
4. 45 min mark → /compact or write new checkpoint
5. Task complete → write final checkpoint, close session
6. Next session → repeat from step 1

The developers who get the most out of Claude Code aren't the ones with the most tokens. They're the ones who manage context like it's a finite resource — because it is.

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Using Claude Code at scale? The context window isn't your only limit — API rate limits hit just as hard on long sessions. SimplyLouie is a $2/month ANTHROPIC_BASE_URL proxy built for developers running extended Claude Code workflows.