Claude Premortem Skill — Development skill for Claude Code

premortem

A Claude Code skill that runs a premortem on any plan, launch, product, hire, strategy, or decision. Imagines the plan failed 6 months from now, works backward to find every reason why, then produces a revised plan with the blind spots exposed.

The method

A premortem is the opposite of a postmortem. Instead of figuring out what went wrong after a failure, you imagine the failure has already happened and explain how, before you start.

• Method: Gary Klein, Harvard Business Review, 2007.
• Kahneman endorsed it in Thinking, Fast and Slow as a counter to overconfidence.

The mechanism: "what could go wrong?" produces hedged, polite answers. "This already failed, explain why" puts the brain into narrative mode and generates specific, honest causes. Wharton and Cornell call this *prospective hindsight*.

This matters for AI assistance. Claude defaults to agreeable. Asking "is this a good plan?" gets reasons it's good. The premortem reframe forces honest failure analysis instead of polite risk assessment.

How it works

Six steps. Linear flow. Parallel sub-agents do the heavy lifting in step 4.

flowchart TD
    A[Plan / launch / decision in] --> B[Step 1: gather minimum context]
    B --> B1{Three things known?
What is it?
Who is it for?
What does success look like?}
    B1 -->|No| B2[Ask one question]
    B2 --> B1
    B1 -->|Yes| C[Step 2: set the premortem frame
It is 6 months from now. The plan failed.]
    C --> D[Step 3: generate failure reasons
comprehensive raw list]
    D --> E[Step 4: write context file, spawn parallel sonnet sub-agents
one per failure reason + one assumption excavator]
    E --> E1[Agent 1: failure A]
    E --> E2[Agent 2: failure B]
    E --> E3[Agent N: ...]
    E --> E4[Excavator: unstated assumptions]
    E1 --> F[Step 5: synthesise + gate]
    E2 --> F
    E3 --> F
    E4 --> F
    F --> F1[Most likely failure]
    F --> F2[Most dangerous failure]
    F --> F3[Hidden assumption]