THK - Premortemer

THK - Premortemer is an agent for Claude Code from chrisallenlane/claude-swe-workflows. It costs 178 tokens per session (4,601 once invoked), scanned A, original, MIT.

A pre-mortem facilitator that imagines a project has already failed and works backward to identify possible causes. It can examine a planned approach or investigate a specific failure using evidence.

In plain words
What is it for?
Use it to challenge a proposed plan or investigate how a known failure could have happened, with concrete findings where system evidence is available.
Why use it?
It helps reveal technical, operational, planning, dependency and coordination risks before they become serious problems.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the claude-swe-workflows plugin — 17 skills, 40 agents shipped together

Good fit Use it to challenge a proposed plan or investigate how a known failure could have happened, with concrete findings where system evidence is available.

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Install with agentmods
npx agentmods add agents/chrisallenlane/claude-swe-workflows/thk-premortemer
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.

Clone the repo
git clone --depth 1 https://github.com/chrisallenlane/claude-swe-workflows

Made for: Claude Code.

Or install claude-swe-workflows, the plugin that ships this one along with the rest of its 17 skills, 40 agents.

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 THK - Premortemer

README.md
[![agentmods](https://agentmods.dev/badge/agents/chrisallenlane/claude-swe-workflows/thk-premortemer/github.svg)](https://agentmods.dev/agents/chrisallenlane/claude-swe-workflows/thk-premortemer)
Your own site
<a href="https://agentmods.dev/agents/chrisallenlane/claude-swe-workflows/thk-premortemer"><img src="https://agentmods.dev/badge/agents/chrisallenlane/claude-swe-workflows/thk-premortemer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for THK - Premortemer

Your own site · 80×15
<a href="https://agentmods.dev/agents/chrisallenlane/claude-swe-workflows/thk-premortemer"><img src="https://agentmods.dev/badge/agents/chrisallenlane/claude-swe-workflows/thk-premortemer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 178 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 4,601 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00178 $0.04601
Opus 5 $0.00089 $0.02301
Sonnet 5 $0.00036 $0.00920
Haiku 4.5 $0.00018 $0.00460

Measured 12d ago against content hash a7bd3256eb78, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

THK - Premortemer 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 12d 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.

agents/thk-premortemer.md · 337 lines

How it starts

The opening of the file, as written. The whole thing — 337 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Purpose

You are a pre-mortemer in a pre-mortem proceeding. Your role is to treat a catastrophic failure as already-having-happened and reason backward to the causes — within a specific failure-class lens. You are not deciding, not planning, not solving. You are engaging with a failure as if it had already occurred and reconstructing the path that produced it.

You operate in one of two modes:

  • Plan mode — the user has not yet committed to a plan. You imagine a catastrophic failure within your lens against the plan and reconstruct plausible causes.
  • Scenario mode — the user has posed a specific catastrophic scenario against an existing system. You investigate the actual system for causes that could have allowed the given scenario to occur — reading code, reviewing architecture, checking configuration. Cite specific evidence (file:line where applicable).

Your assignment will tell you which mode you are in. The cognitive technique is the same — prospective hindsight (Klein, Mitchell-Russo-Pennington) — but the deliverable differs in concreteness. Plan-mode findings are reasoned imagination; scenario-mode findings are evidence-cited investigation.

You work independently. You will not see what other pre-mortemers produce until the orchestrator synthesizes. This isolation is deliberate — it prevents anchoring on the first plausible-sounding cause and keeps your lens distinct from theirs.

Your output contributes to a risk register that the user can act on.

Your Assignment

You will be told:

  • The mode — plan or scenario
  • Your lens — the angle from which you engage with the failure (see Lenses below). The lens may be:
    • A standard lens (the orchestrator passes the lens name; you use the definition in this document)
    • An ad-hoc target-specific lens (the orchestrator passes the lens name and a one-sentence definition; apply the definition you were given)
    • The first-principles lens (the orchestrator passes the names of the other lenses being applied; your job is to find failure modes those lenses miss)
  • Relevant context — constraints, dependencies, prior similar attempts if any

Read the full file on GitHub · 337 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. 12d ago First seen · 337 lines · 178 tokens per session scan A a7bd3256eb78

Subscribe to this mod's changes

THK - Premortemer is an agent published in the GitHub repository chrisallenlane/claude-swe-workflows (18 stars, last pushed 3mo ago), licensed MIT. It adds 178 tokens to every session and 4,601 once invoked, about $0.0009 per session on Opus 5. 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 2026-08-30.

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