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.

Every spawn is a general-purpose agent, the type that carries MCP tools: the MCP-backed investigators need them, and so do the synthesizer's citation spot-checks. Investigators write nothing.

Operating Posture

Operate as a careful, cautious, and precise investigator. Be honest about what you know vs what you're inferring. Read references/epistemics.md for the full confidence framework and phrasing guide. The synthesizer must follow it.

Step 1. Understand the Target and the Question

The target is usually a chunk of code, a pattern, a feature, or a named design decision. The question is usually a design rationale, a tradeoff, a motivating edge case, an external constraint, dead code, or a broad history sweep.

If the target is vague ("why do we do it this way?" with no clear referent), make your best guess from conversation context (open files, recent edits, what was just discussed). State your interpretation briefly so the user can redirect if you're off, then proceed.

Step 2. Establish the Code Anchor

Before spawning investigators, build the seed context inline: file paths and line ranges, key symbols (functions, classes, constants), the last few commits touching the target, PR numbers from merge commits (pattern (#1234) in the subject line), and any linked ticket IDs. Run git blame -L <start>,<end> <file> for last-touch commits, git log --follow -p -- <file> for full history with patches through renames, git log --oneline -20 -- <file> for recent commits with PR numbers visible, and git log -1 --format=%B <commit> to extract PR numbers. Then pull the PR bodies and discussion for any substantive commit: gh pr view <number> --json title,body,author,createdAt,mergedAt,labels,closingIssuesReferences,comments,reviews. This anchor goes to every investigator and to the synthesizer.