Add implement-spec skill (in-progress) with its bucket docs

The skill itself takes a spec plus its tickets and drives them to one
PR, reading the tickets as a task graph so implementer subagents can run
concurrently across the ready frontier.

Documentation duties for the in-progress bucket:

- List it in skills/in-progress/README.md (flat list, name linked to its
  SKILL.md), the one entry every skill in a bucket must have. It stays
  out of the top-level README and .claude-plugin/plugin.json, and gets no
  docs page, as the bucket requires.
- Add a changeset, so the release notes carry it.
- Match the bucket's openai.yaml style in short_description: a short verb
  phrase, no closing period.

Also ignore .claude, which holds settings.local.json and agent worktrees
that should never be committed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: mattpocock

.changeset/add-implement-spec-skill.md

@@ -0,0 +1,5 @@
+---
+"mattpocock-skills": patch
+---
+
+Add the `implement-spec` skill (in-progress bucket, user-invoked). It takes a spec and its tickets and drives them to a single PR: the tickets are read as a task graph with blocking edges, so implementer subagents run in background worktrees across the ready frontier for concurrency, a merger subagent folds each one back into the PR branch, and the flow closes with `/code-review` before the PR is marked ready.

.gitignore

@@ -1 +1,2 @@
 node_modules
+.claude

skills/in-progress/README.md

@@ -14,3 +14,4 @@ npx skills@latest add mattpocock/skills --skill=<name>
 - **[writing-shape](./writing-shape/SKILL.md)**: Take a markdown file of raw material and shape it into an article paragraph by paragraph, arguing format choices at each step.
 - **[claude-handoff](./claude-handoff/SKILL.md)**: Hand the current conversation off to a fresh background agent that picks up the work immediately, seeded with a handoff summary via `claude --bg`. User-invoked.
 - **[setup-ts-deep-modules](./setup-ts-deep-modules/SKILL.md)**: Wire dependency-cruiser into a TypeScript repo so each package is a deep module: implementation hidden in subfolders, reachable only through its entry-point files, tests exercising it through those. User-invoked.
+- **[implement-spec](./implement-spec/SKILL.md)**: Implement a whole spec on one branch. Works the tickets as a task graph rather than a list, running implementer subagents across the ready frontier for maximum concurrency, and lands the result as a single PR. User-invoked.

skills/in-progress/implement-spec/SKILL.md

@@ -0,0 +1,35 @@
+---
+name: implement-spec
+description: "Implement a specification in code."
+disable-model-invocation: true
+---
+
+You have been provided a spec. This spec should have tickets associated with it, describing how to implement the spec.
+
+The goal is a PR which implements the entire spec on a single branch.
+
+The tickets are not a list of steps. They are a **task graph** with blocking relationships between them. This means there is always a **frontier** of tickets which are ready to be grabbed.
+
+Communication to and from subagents should be sparse. Communicate primarily through **context pointers**: to the spec, tickets, research notes, and previous commits. Don't duplicate information already available via pointers.
+
+**Implementer subagents** should be run in the background where possible for **maximum concurrency**.
+
+## Steps
+
+1. Read the spec and tickets. Read enough to understand the task graph.
+
+2. (optional) Use an **exploration subagent** to conduct any exploration required by the tickets - relevant codebase files or external documentation. Ensure the exploration subagent can save files - it should save its markdown notes in a directory outside the repo, accessible by all future subagents. This lets **implementer subagents** focus on implementation rather than exploration.
+
+3. Create a branch, and a draft PR. The PR should be marked as 'closing' the spec issue and tickets.
+
+4. Use **implementer subagents** to implement each ticket. Each implementer subagent should work in its own worktree, on its own branch.
+
+5. Once an **implementer subagent** completes, merge its work to the PR branch with a **merger subagent**.
+
+6. If this changes the **frontier** of available tickets, kick off more **implementer subagents** to work on the new tickets. This allows for maximum concurrency.
+
+7. Once all tickets are complete, run /code-review on the PR branch. Fix all issues raised by the code review in an **implementer subagent**.
+
+8. Mark the PR as ready for review.
+
+9. Clean up all **implementer subagent** worktrees.

skills/in-progress/implement-spec/agents/openai.yaml

@@ -0,0 +1,5 @@
+interface:
+  display_name: "Implement Spec"
+  short_description: "Implement a whole spec as one PR"
+policy:
+  allow_implicit_invocation: false