skills: add gip — grab issues in parallel

[d-morrison]

What

Adds a new skill, gip (Grab Issues in Parallel) — the parallel counterpart to the deliberately-serial gii. It grabs several open issues and works them concurrently: one worktree-isolated subagent per issue, each claiming, checking history, implementing, opening a PR, and ARDI-ing it to clean.

Closes #136.

Why

We have the serial family — gi (one issue), gii/gis (loop the backlog serially), gia (clean PRs then loop issues). gii is serial on purpose: a later issue's base branch can depend on a prior unmerged MR, and two issues touching the same files would conflict. But when a batch is provably independent, one-at-a-time just wastes wall-clock time. gip fills that gap without giving up the safety gii was protecting.

How it stays safe

The load-bearing part is the independence gate: gip partitions the in-scope issues into

• an independent set — each branches straight from origin/main, no file overlap, not blocked → fanned out concurrently, each subagent in its own git worktree (Agent isolation: "worktree"), capped at ~3 to avoid swamping CI runners; and
• a dependent remainder — anything stacked or file-overlapping → sent back through the serial gii loop.

Bias is "when unsure, serialize." Each subagent prompt is self-contained (restates the full per-issue procedure), since a spawned subagent starts fresh and can't read the skill file.

Files

• skills/gip/SKILL.md — canonical skill.
• skills/grab-issues-in-parallel/SKILL.md — spelled-out alias.
• skills/gii/SKILL.md, skills/gia/SKILL.md, skills/pr-status-all/SKILL.md — symmetric cross-links. pr-status-all previously asserted the issue write-loops always "stay series"; that's now nuanced with gip as the opt-in exception.

🤖 Generated with Claude Code

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Generated by Claude Code

[claude]

Claude finished @d-morrison's task in 2m 57s —— View job

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Code Review — PR #137: gip skill (re-review after eb18057)

• Read all 5 changed files
• Verify previous 3 findings were addressed in eb18057
• Review skills/gip/SKILL.md (main skill) for new issues
• Review skills/grab-issues-in-parallel/SKILL.md (alias)
• Review cross-link additions to gii, gia, pr-status-all
• Check for AI hallucinations and fabricated references

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Verdict: clean

All three findings from the previous round are confirmed fixed.

Finding 1 — hallucinated CLAUDE.md mapping table (skills/gip/SKILL.md:57): Fixed. The parenthetical now reads "use the GitHub MCP tools instead (e.g. add_issue_comment, create_pull_request, search_pull_requests)" — concrete, verifiable, no phantom reference.

Finding 2 — hardcoded d-morrison reviewer (skills/gip/SKILL.md:136): Fixed. Step 6 in the subagent prompt now opens the PR with no reviewer specified, matching gi's behavior.

Finding 3 — ambiguous "or alongside" (skills/gip/SKILL.md:152): Fixed. Step 5 now reads "After the parallel wave" — unambiguous sequential ordering.

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No new issues found

• All referenced skills exist: gi, gii, gis, gia, ardi, ardia, session-lock, check-history, defer-issue, split-concerns, pr-status-all, grab-issue.
• The grab-issues-in-parallel alias path (~/.claude/skills/gip/SKILL.md) is consistent with the pattern used by gis.
• The independence gate logic and worktree isolation rationale are coherent and correct.
• The pr-status-all update correctly nuances the "write-loops always stay series" rule by naming gip as the opt-in exception.
• Cross-links in gii and gia are symmetric and accurate.
• No fabricated symbols, URLs, or config keys.