Why

When you're staring at code wondering why it was built this way instead of the obvious alternative, this skill fans out across seven evidence categories in parallel: commit history, tickets, docs, chat logs, observability, error tracking, and analytics. It doesn't guess from the code itself. It pulls actual artifacts, cites them, and tells you when the trail goes cold. The epistemics are careful to a fault: hedged language when evidence is thin, contradictions surfaced rather than smoothed over, gaps documented instead of papered over with confident speculation. Think forensic investigation, not storytelling. You get a patchwork of what's findable, not a tidy narrative about what probably happened.

skills.sh installs: 6.5K
GitHub stars: 15.9K
last updated: Aug 21, 2026

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Install

$ npx -y skills add cursor/plugins --skill why --agent claude-code

Installs into .claude/skills of the current project.

Files

Why

Investigate the motivation and intent behind code. The companion how skill answers what the code does and how it works. why answers what forces led to its shape.

Each spawn below names a role line in the pstack-models.mdc rule and a default. Set model to that line's value, or to the default if the rule or the line is missing. Leave model unset when the value is auto or inherit-parent. If the Task tool rejects a slug, use the default and say so. If it rejects the default, use the closest valid slug of the same family from its error message. Pick each subagent's reasoning level and fast or standard speed for the job, per the Subagents section of the poteto-mode skill.

Every spawn is generalPurpose with readonly: false (agent mode). Do not use readonly/Ask mode. It strips MCP access, which disables the MCP-backed investigators and the synthesizer's citation spot-checks. Investigators still shouldn't write anything.