why

Investigate design rationale behind code by querying git history and MCP evidence sources in parallel.

1|Updated Aug 26, 2026
One-click install
npx skills add https://github.com/edivad1999/stuc-stack --skill why-edivad1999
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: why
Source: https://github.com/edivad1999/stuc-stack/tree/main/skills/why
Command: npx skills add https://github.com/edivad1999/stuc-stack --skill why-edivad1999

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve? Code rarely explains why it exists. This Skill answers "why does X work this way" questions by investigating the historical record—commits, PRs, tickets, docs, chat, telemetry, and analytics—so you get a cited, confidence-weighted answer instead of a guess. ## Core Features & Use Cases - Parallel Evidence Investigation: Spawns one investigator subagent per available evidence category (source control, issue tracker, long-form docs, team chat, observability, error tracking, analytics warehouse), each with a source-specific playbook. - Calibrated Confidence Output: Synthesizes findings into Direct / Supported / Inferred / Speculative / Unknown tiers with verbatim citations, contradictions surfaced, and gaps explicitly documented. - Change-Planning Constraints: Converts lineage findings into a Preserve / Change / Avoid / Risk constraint set when the question precedes a code change. - Use Case: You find a mysterious retry limit of 3 in a payment service. The Skill traces the PR, finds the linked incident postmortem and Sentry spike, and reports the threshold was chosen after a specific outage—with citations. ## Quick Start Ask the agent why a specific function, threshold, or pattern in your codebase exists and let it investigate the historical evidence.

Frequently Asked Questions about why

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I find out why a piece of code was written a certain way?▼

Anchor the investigation with git blame and git log on the target lines, then pull PR bodies via gh or glab. This Skill automates that and fans out parallel investigators across tickets, docs, chat, and telemetry to gather cited evidence.

What is the difference between the why and how skills?▼

The how skill explains what the code does and how it works at runtime. The why skill explains the forces that led to its shape: design rationale, tradeoffs, incidents, and external constraints found in the historical record.

Does this work without MCP servers configured?▼

Yes, but with reduced coverage. Source control investigation via git and gh always runs; other categories like Slack, Notion, Linear, Datadog, Sentry, or Databricks require matching MCP servers, and missing ones are documented as gaps.

How does it handle questions with no documented answer?▼

It reports an explicit Unknown tier, listing exactly which sources were searched, which queries ran, and what returned nothing. Gaps are named concretely rather than filled with plausible-sounding guesses.

Can it investigate defensive code like retries and null checks?▼

Yes. When the target looks defensive, investigators also apply a cross-cutting incident-postmortem playbook, hunting for outage history, Sentry error spikes, and postmortem action items that motivated the code.