Claude Code: Clear Context vs Keep Context for Complex Tasks

Claude Code is Anthropic's agentic coding CLI (also available as a VS Code, JetBrains, Desktop, and web client). Its plan mode lets the model read, search, and write a proposed plan without editing source files. You enter plan mode by pressing `Shift+Tab` to cycle modes (`default` → `acceptEdits` → `plan`, with `auto` and `bypassPermissions` slotted in if enabled), by passing `--permission-mode plan` at startup, or by prefixing a single prompt with `/plan`. When the plan is ready, Claude presents it and offers several exit options: 1. **Approve and start in auto mode** — execute without permission prompts; a separate classifier model gates dangerous actions like `curl | bash`, force-push to `main`, or sending secrets to unknown endpoints. 2. **Approve and accept edits** (`acceptEdits`) — file edits and a small set of filesystem Bash commands (`mkdir`, `touch`, `mv`, `cp`, `rm`, `sed`) run without prompting, but other shell commands still ask. 3. **Approve and review each edit manually** — default permission flow; every edit and command prompts. 4. **Keep planning** with feedback, or open the plan in `$EDITOR` with `Ctrl+G` to edit it before proceeding. 5. Refine with Ultraplan for browser-based review of a Claude-on-the-web session. When the `showClearContextOnPlanAccept` setting is enabled (now the default in current releases), each approve option offers a "clear context first" variant. "Yes, clear context and auto-accept edits" is highlighted as the default selection. Clearing wipes the planning conversation from the context window but keeps the written plan file, which Claude re-reads as its working brief. ## Why clearing usually wins The context window is a finite token budget shared by the system prompt, CLAUDE.md instructions, tool definitions, conversation history, file reads, and tool outputs. Plan mode burns a lot of that budget on exploration: directory listings, file reads, grep results, and the agent's own reasoning about what to change. Once a plan exists, those raw exploration artifacts are mostly dead weight — the plan already distills what matters. Carrying them into execution accelerates context exhaustion and triggers context compaction, which can drop boundaries, instructions, and partial state at unpredictable moments. Anthropic introduced auto-clear because their internal testing showed it materially improves plan adherence on long tasks: the implementation session starts with the plan as its primary instruction rather than a stale, sprawling exploration transcript that competes for attention. This mirrors the broader Context Management Patterns for Long-Running AI Agents finding that periodic state resets outperform indefinite history accumulation. ## Why you might keep context Clearing context **loses anything not in the plan file**, including: - Inline coding-style guidance you gave mid-session ("prefer functional style here", "don't touch the legacy module") - Files you asked Claude to read for reference but didn't list in the plan - Test output or error messages from earlier debugging - boundaries you stated in conversation (in auto mode the classifier re-reads the transcript each check, so cleared boundaries stop applying) - Clarifications about ambiguous requirements Keep context when the conversation built up nuance that the written plan doesn't fully capture, when you're on a short task where context pressure isn't a concern, or when you've configured deny rules and prefer to rely on stated boundaries. ## Persistent context survives clearing Only the live conversation gets cleared. These persist across the clear (and across sessions entirely): - **CLAUDE.md** at organization, user (`~/.claude/CLAUDE.md`), project (`./CLAUDE.md` or `.claude/CLAUDE.md`), and local (`./CLAUDE.local.md`) scope. Loaded broadest-to-narrowest at session start. You can `@import` other files into it. - **AGENTS.md Standardization: Why Cursor, Aider, Codex, and Devin Converged on One File** if symlinked or imported from CLAUDE.md. - **auto memory** — Claude's own notes saved to `~/.claude/projects/<project>/memory/MEMORY.md`. First 200 lines (or 25KB) load at session start; topic files load on demand. - `.claude/rules/` path-scoped instruction files with YAML frontmatter targeting specific globs. - slash commands (custom skills under `.claude/commands` or `.claude/skills`) and hooks (shell commands run on `PreToolUse`, `PostToolUse`, `PermissionRequest`, etc.). - MCP server configs in `.mcp.json` and any tool definitions they expose. See Building AI-for-AI Knowledge Layers with MCP. For rules you absolutely cannot lose — formatters, lint gates, deny rules on dangerous paths — use hooks or `permissions.deny` rather than chat boundaries. The harness enforces those regardless of what's in context. ## When the clear-and-auto-accept default is appropriate - **Thorough multi-file refactors** where the plan enumerates every file and intent. The implementation phase mostly executes mechanically. - **Test-driven feature work** where the plan specifies the test cases and the new module shape. - **Migration scripts** where the plan lists every transformation step. - Anything you'd be comfortable running headless via `claude -p`. ## When to keep context (or skip plan mode) - **Exploratory debugging** where the conversation surfaces hypotheses that aren't in any plan. - **Tasks with strong inline guidance** you gave conversationally and don't want to rewrite into the plan. - **Short tasks** (<10 minutes of editing) where context exhaustion isn't a real risk. - **Sensitive work** where you'd rather see each prompt — use default mode and skip the auto-accept exit entirely. ## Related controls - `/clear` — wipe context manually at any time (not just on plan accept). - `/compact` — summarize conversation history in place when nearing the context limit. Less destructive than `/clear` but lossier than starting fresh with a plan. - `/memory` — view all loaded CLAUDE.md and memory files; toggle auto memory. - `/rename` — name the session manually (accepting a plan auto-names it from plan content). - `defaultMode` in `.claude/settings.json` — set plan mode as the project default so every session starts there. - Proactive output style — keep prompts but nudge Claude to push through without clarifying questions, as a lighter alternative to auto mode. The broader pattern: in long agentic sessions, the most valuable thing you can do for plan adherence is keep the working context lean and load-bearing. See Prompt Caching in LLMs: How Reusing Context Cuts Cost and Latency for why a smaller, stable context is also cheaper, and Caveman Skill and the Brevity Research: 65-75% Token Reduction That Improves LLM Accuracy for the accuracy gains brevity buys.