Add git-blame-historic-context skill

[AryanGodara]

What this is

A standalone procedure for using git blame to recover historic context before flagging unusual-looking code. Often, certain decisions led to sub-optimal-looking code, and those decisions are codified in git history rather than the code itself. This skill formalises the lookup + decision rubric.

Ships with /blame-context <path>:<line>, a slash command that wraps the procedure end-to-end. Use either the slash command or the procedure manually.

Why split out

Extracted from #4351 because the procedure is reusable beyond PR review — order-debug sessions and ad-hoc code investigations both want the same lookup play. Splitting keeps each consumer's surface focused.

Files

• docs/skills/git-blame-historic-context.md — the procedure + decision rubric.
• .claude/commands/blame-context.md — slash command wrapping the procedure.

Reviewing this in isolation

The skill body is self-contained. The "Used by" footer links to ../COW_PR_REVIEW_SKILL.md, which lands with #4351; that link will 404 until that PR merges. Nothing else here depends on #4351.

How to try it

/blame-context crates/driver/src/domain/competition/solution/settlement.rs:444
/blame-context crates/observe/src/panic_hook.rs:14-15

Worked sample output for both is in the skill file's Examples section.

[gemini-code-assist]

Code Review

This pull request introduces a new Claude command and detailed documentation for the 'git blame historic context' skill, which assists developers in understanding the rationale behind unusual code by tracing it back to its originating PR. The feedback focuses on improving the automation of the gh pr view command by removing unnecessary repository flags that would require manual variable substitution, allowing the CLI to infer the context automatically.