premortem

premortem is a skill for Claude Code, Codex from sjarmak/agent-workflows. It costs 0 tokens per session (1,683 once invoked), scanned A, original, MIT.

A premortem review that imagines a project has already failed, asks several independent reviewers to explain why, and combines their stories into a ranked risk list with mitigations.

In plain words
What is it for?
Use it with a design document, architecture document, PRD, project plan, or project description to identify technical, operational, and planning risks.
Why use it?
It helps teams find likely failure causes that ordinary planning may overlook before work starts.

Skill for Claude CodeCodex

Part of the agent-workflows plugin — 28 skills, 4 agents, 4 hooks shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/sjarmak/agent-workflows/premortem
Any agent
npx skills add sjarmak/agent-workflows --skill premortem
Clone the repo
git clone --depth 1 https://github.com/sjarmak/agent-workflows

Made for: Claude Code, Codex.

Or install agent-workflows, the plugin that ships this one along with the rest of its 28 skills, 4 agents, 4 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for premortem

README.md
[![agentmods](https://agentmods.dev/badge/skills/sjarmak/agent-workflows/premortem.svg)](https://agentmods.dev/skills/sjarmak/agent-workflows/premortem)
Your own site
<a href="https://agentmods.dev/skills/sjarmak/agent-workflows/premortem"><img src="https://agentmods.dev/badge/skills/sjarmak/agent-workflows/premortem.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,683 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.01683
Opus 5 $0.00000 $0.00842
Sonnet 5 $0.00000 $0.00337
Haiku 4.5 $0.00000 $0.00168

Measured 5d ago against content hash 505a54514788, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

premortem scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/premortem/SKILL.md · 169 lines

How it starts

The opening of the file, as written. The whole thing — 169 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Prospective Failure Narratives. Spawns N independent agents, each writing a narrative from the future where the project FAILED for a different root cause. No agent sees others' failure stories. A lead agent then synthesizes all failure narratives into a structured risk registry with severity ratings and mitigations.

Based on Gary Klein's premortem technique: "prospective hindsight" — imagining an event has already occurred — increases the ability to identify reasons for future outcomes by ~30%. Starting from "it failed" bypasses the planning fallacy and optimism bias that normally prevent teams from envisioning failure modes.

Arguments

$ARGUMENTS — format: [N] [path/to/design.md or inline description] where N is optional failure-lens count (default: 5, min 3, max 7)

Parse Arguments

Extract:

  • agent_count: the optional leading integer (default 5, min 3, max 7)
  • input: path to a design document, architecture doc, PRD, or project plan — or an inline project description

If the input is missing or unclear, ask the user to clarify before proceeding.

Phase 1: Frame the Project

If a file path is given: read it and extract the key design decisions, architecture, dependencies, and assumptions.

If inline: parse the project description.

Prepare a project brief that includes:

  • What is being built
  • Key technical decisions
  • Dependencies (internal and external)
  • Timeline constraints
  • Team context (if available)
  • Critical assumptions

Present the project brief to the user and confirm before proceeding. Adjust if the user gives feedback.

Phase 2: Spawn Failure Agents

Launch all N agents in parallel using the Agent tool. Each agent gets the same project brief and a unique failure lens — a category of failure they must explore.

Standard Failure Lenses

Select N from the following (always include lenses 1-3, then fill remaining slots in order):

  1. Technical Architecture Failure — the core technical approach was wrong (scaling limits, fundamental design flaw, performance cliff, wrong data model)
  2. Integration & Dependency Failure — external dependencies failed or changed (API deprecation, library vulnerability, vendor shutdown, incompatible upgrade)
  3. Operational Failure — the system works in dev but fails in production (deployment complexity, monitoring gaps, incident response blind spots, data migration corruption)
  4. Scope & Requirements Failure — we built the wrong thing (misunderstood requirements, missed stakeholder needs, wrong assumptions about user behavior)
  5. Team & Process Failure — the people-side failed (knowledge silos, handoff gaps, testing shortcuts, documentation debt)
  6. Security & Compliance Failure — security breach, data leak, regulatory violation, access control gap
  7. Scale & Evolution Failure — works at current scale but breaks at 10x (database bottleneck, cost explosion, architectural ceiling)

Read the full file on GitHub · 169 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 169 lines · 0 tokens per session scan A 505a54514788

Subscribe to this mod's changes

premortem is a skill published in the GitHub repository sjarmak/agent-workflows (9 stars, last pushed 1mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,683 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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