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.