Claude Code's context window is your most valuable resource, and most people burn through it in the first 10 minutes. Here's what context window mismanagement looks like in practice: you open a session, paste in a 2,000-line file, ask Claude to "review everything," then wonder why it starts hallucinating or forgetting earlier instructions by message 15. The fix is simple but requires changing how you think about sessions. Rule 1: Scope every session to ONE task. Not "build me a full dashboard." Say "add a date filter to the existing analytics table in dashboard.tsx." Smaller scope means context lasts longer, which means better output. Rule 2: Use /clear strategically. When you switch to a new file or new feature, type /clear to reset. Don't carry baggage from 30 messages ago into the next task. Rule 3: Pin your project brief at the top of every session. A 150-word summary of what the codebase does, your stack, and what NOT to touch. This costs almost nothing in tokens but prevents Claude from re-reading 5 files just to figure out what you're building. Rule 4: Use CLAUDE.md for persistent context. Architecture decisions, naming conventions, deployment notes. Claude Code reads this automatically at session start. Anything that applies every session goes there. Rule 5: Don't paste full files unless asked. Use "see file: src/components/Button.tsx" first. Let Claude request the file when it needs it. This preserves your window for actual work. I tested this on a 3,000+ line codebase last week. Sessions that used to drift and need restarts after 20 messages now run clean for 60+ messages doing real work. What's your current context management strategy, or are you just running sessions until they break?