/why

name: why
description: "Investigate why code is the way it is from evidence — human rulings verbatim, git archaeology, linked issues, incident records — every claim labeled evidence, inference, or guess. For 'why was this built this way'."
aliases: []
metadata:
  credits:
    investigation-epistemics: pstack
    author: Lauren Tan
    url: "https://github.com/cursor/plugins/tree/main/pstack"
    port: pstack-claude
    port-author: Michael Denyer
    port-url: "https://github.com/michael-denyer/pstack-claude"

Why

Answer "why is it like this?" from evidence, not vibes. The deliverable is a cited answer, not a fix; a fix that falls out of the answer goes through its own lane.

When to use

• "why was this built this way", "why does this exist"
• "are we sure about Z" before betting work on Z
• "should we do X or Y" where the answer lives in history, not preference

Sources, in order of authority

1. **Human rulings.** A decision a person made is quoted verbatim with attribution (commit message, issue comment, PR review, chat log). Never paraphrase a ruling into your own words; label agent interpretations as interpretations, and missing originals as missing. A copy of a ruling is not a new decision. 2. **Code archaeology.** `git log --follow`, `git log -S`, blame on the deciding lines, and the diff that introduced them. Name the commit and what problem its message claims to solve. 3. **Linked records.** Issues and PRs reachable from the code (references in commit messages, `gh issue list --state all --search`, PR review threads) — acceptance criteria and rejected alternatives live here. 4. **Incident and observability sources.** When configured, query them through their own tools (Sentry, Datadog, Databricks, dashboards, incident postmortems) or MCP servers (Slack, Linear, Notion). Cite the alert, thread, ticket, or postmortem. If a source needs credentials you do not have, say so and move on.

Method

1. State the question and what would count as an answer. 2. Fan out source gathering to a read-only subagent when the history is long (`oh-my-claudecode:explore`); keep synthesis in the lead. 3. Reconcile: where sources conflict, the more authoritative source wins, and the conflict itself is reported. 4. Write the answer with three labeled tiers — **evidence** (cited), **inference** (your reasoning from evidence, marked), **guess** (marked). End with the one action the answer most supports, or "no action".

Rules

• Every claim about a past decision names its source in the same sentence.
• Absence of evidence is reported as "no record found", never as "no reason".
• The answer never edits code. If the user asks to act on it, hand off to

`execute` or `debug`.