Claude Code: The 5× Token Trap Using Plan Mode

You just finished planning. The approach is locked, the plan is on disk. Now you start building — dragging 100K tokens of dead-end searches into every implementation turn. That's the 5× trap. For API users, that is $5–15 of avoidable spend per heavy session. For Max/Pro subscribers, it means hitting your usage limit dramatically sooner.

Here's why /clear is almost always the better move, and when it isn't.

Why does planning context hurt implementation?

A planning session is messy by design: exploratory file reads, dead-end searches, abandoned approaches, stale code snapshots. By the time you start building, the useful signal — chosen approach, key files, constraints — is a few kilobytes. The rest is noise that taxes every subsequent turn because Claude Code resends the full conversation history with each request.

If your plan is already saved to disk, the conversation is mostly liability.

Should you /clear, /compact, or keep everything?

/clear after planning is the recommended default. Claude Code's own best-practices docs advise clearing between tasks and after repeated failed corrections — both of which describe the plan-to-build transition. Re-reading the plan file and a few source files is cheap, deterministic, and loads current file state instead of stale in-context copies.

/compact is a fallback, not a replacement. Compaction produces a lossy LLM summary that may silently drop details you need. It is designed to be cache-aware and prefix-preserving, but the summary still carries noise from exploration you no longer need. Use it only when you are mid-task without a durable artifact.

Keeping everything is the most expensive option. You re-process stale context on every turn, and if the window fills up, auto-compaction fires at an arbitrary moment — the worst-quality outcome.

How much does stale context actually cost?

Assume a planning session leaves ~120K tokens of context but implementation only needs ~20K. That is 100K tokens of noise carried across every turn.

At current Opus 4.7 pricing ($5/M input, $0.50/M cache read), the per-session waste depends on cache-hit rate and turn count — but the ratio matters more than the dollars: you are processing roughly 5× the context you need on every turn. For API users, that is $5–15 of avoidable spend per heavy session. For Max/Pro subscribers, it means hitting your usage limit dramatically sooner.

What do you lose by clearing?

Not the plan — that is on disk. You lose unwritten reasoning: why you rejected approach B, a hidden dependency you noticed mid-exploration.

The fix: before clearing, ensure the plan file captures the why, not just the what. If it does, clearing is effectively lossless.

The rule of thumb

  • Multi-file feature or heavy context → /clear, then implement from the plan
  • Quick change, light context → just keep going
  • Mid-task, no durable artifact yet → /compact with explicit preserve instructions
  • Always: confirm the plan captures rejected alternatives and key reasoning before clearing

TL;DR

Your planning session leaves ~120K tokens of context. Implementation needs ~20K. That's 5× the noise on every turn — burning tokens, money, and code quality. If your plan is saved to disk, /clear beats /compact every time. /compact is for when you're mid-task with no durable artifact.

Frequently asked questions

Should I /compact or /clear after planning in Claude Code?

/clear — if your plan is saved to disk. The plan file is the signal; the exploration conversation is noise. /clear gives implementation a full context budget without the per-turn cost of stale context. General guidance recommends /compact for same-task continuity, but planning and implementation are different tasks with different context needs — the plan file bridges them better than a lossy summary.

Don't the docs say /compact is better for staying on the same task?

They do — /compact is designed to keep your current task context alive while trimming history. But a planning session's context is mostly exploration noise that implementation never needs. The plan file carries the decisions forward more reliably than a compressed summary. If you must stay in-session, use /compact with explicit instructions — e.g., /compact keep the auth refactor decisions, drop the failed test runs — to steer what the summary preserves.

Does /clear delete my plan or my files?

No. /clear resets the conversation window only. Any files on disk — including your plan — are untouched. Your CLAUDE.md project conventions are also reloaded automatically in the new session.

Can I recover my planning session after /clear?

Yes. Previous sessions remain available via /resume. /clear hides the conversation from the active context window — it does not delete history. If you realize mid-implementation that you need a detail from planning, you can resume that session.

Does stale context hurt code quality, not just cost?

Yes. A window full of exploration noise gives the model more irrelevant material to attend to, which can degrade focus. Implementation in a clean window tends to produce tighter, more plan-adherent code. When the model keeps misapplying earlier corrections or re-asks for paths it already edited, that is context degradation in action — and /clear is the fix.

What if I didn't save a plan file before I need to clear?

Don't clear yet. First, ask Claude to write the plan to disk — include rejected approaches and key reasoning, not just the final decisions. Once the plan captures the why and not just the what, /clear becomes safe. Without a durable artifact, use /compact with explicit preserve instructions as the fallback.

Meta description: Should you /clear or /compact after planning in Claude Code? /clear wins — it cuts per-turn context by 5×, saves tokens and money, and produces sharper implementation. Here's the math and the workflow.

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