Plan-Validate-Execute Pipeline

Overview

Plan-Validate-Execute is a three-phase pipeline that applies as soon as a task touches more than five files or two directories. The goal: never execute without having validated an explicit plan. Boris Cherny (Head of Claude Code at Anthropic) starts 80% of his tasks in Plan Mode for this reason — execution is almost always correct on the first try when the plan is solid.

Phase 1: Plan

Enter Plan Mode (read-only) so Claude can analyze and propose a detailed action plan before writing a single line.

# Activate Plan Mode
Shift+Tab x2   # From Normal Mode

# Or via slash command
/plan

# Claude generates a structured plan:
# 1. Read schema.prisma
# 2. Add the field email: String? @unique
# 3. Generate the Prisma migration
# 4. Update TypeScript types
# Impact: 3 files, 1 migration

Exit Plan Mode: Shift+Tab (back to Normal Mode). Claude will ask for confirmation before implementing.

Phase 2: Validate

Before approving the plan, submit it to a critical review. Two approaches:

Manual review: read the plan and identify blind spots (forgotten files, incorrect operation order, unanticipated side effects).

Adversarial agent: delegate the critique to a sub-agent whose mission is to find flaws in the proposed plan. Ask explicitly: “What is the main risk of this plan? What could go wrong?”

Validation is not optional on complex tasks — it is the safety net.

Phase 3: Execute

Once the plan is validated, execute with regular checkpoints.

# Exit Plan Mode and execute
Shift+Tab   # Back to Normal Mode
> "Approve this plan and implement step by step"

# For very long tasks: create tasks before executing
export CLAUDE_CODE_TASK_LIST_ID="project-migration-v2"
# Then TaskCreate from the validated plan

Tasks API integration

Convert the validated plan into persistent tasks before execution. Each step of the plan becomes a task with its declared dependencies. If the session is interrupted mid-execution, TaskList allows resuming exactly where you left off.

When to apply this pipeline

For quick fixes and known tasks, the pipeline adds more friction than value. The right reflex: question the complexity before launching, not after.

Auto Plan Mode

Force Plan Mode on all operations via --append-system-prompt:

alias claude-safe='claude --append-system-prompt \
  "$(cat ~/.claude/auto-plan-mode.txt)"'

The auto-plan-mode.txt file instructs Claude to present a plan and wait for explicit approval before each tool. Useful for sessions on critical or unfamiliar codebases.