skill: add /close-feature + document cross-machine skill setup

- New /close-feature skill graduates .scratch/<slug>/ to docs/ when all
  issues are done; also offers to run proactively when it detects a complete
  feature. Documents machine setup steps (Linux/Mac, Windows, Codex, new skill
  install) in the skill itself.
- Fix AGENTS.md issue-tracker line to reflect the .scratch → docs/ workflow.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.agents/skills/close-feature/SKILL.md

@@ -0,0 +1,115 @@
+---
+name: close-feature
+description: Graduate a completed feature from .scratch/<slug>/ into the permanent docs/ structure. Run when all issues in the feature are done, or when the agent notices a feature looks complete. Always confirm with the user before moving files.
+---
+
+# Close Feature
+
+Merge a completed `.scratch/<slug>/` feature into the permanent `docs/` structure and delete the scratch directory.
+
+## When to run
+
+Run this skill when:
+- The user explicitly calls `/close-feature <slug>`
+- You notice during any task that ALL issues in a `.scratch/<slug>/issues/` directory have `Status: done` — surface this proactively and offer to close ("It looks like <slug> is fully done. Want me to graduate it to docs/?")
+
+Always confirm before moving any files.
+
+## Process
+
+### 1. Identify the slug
+
+If called with an argument (`/close-feature <slug>`), use that. Otherwise list all `.scratch/` directories and ask the user which one to close.
+
+### 2. Verify all issues are done
+
+Read every file in `.scratch/<slug>/issues/`. Check for a `Status:` line.
+
+If any issue does NOT have `Status: done`, list the incomplete ones and stop — ask the user whether to mark them wontfix or wait.
+
+### 3. Show the user what will move
+
+Present a summary:
+- N issues → `docs/issues/` (renumbered from next available)
+- PRD.md → `docs/PRD.md` (or merged if one already exists)
+- prd.json → `docs/prd.json` (merged into existing user stories array)
+- Any ADRs written during the feature → `docs/adr/` (renumbered from next available)
+- `.scratch/<slug>/` deleted
+
+Ask: "Proceed?" before touching anything.
+
+### 4. Move issues
+
+Find the highest existing number in `docs/issues/`. Issues from `.scratch/<slug>/issues/` take the next slots in dependency order (lowest numbered first).
+
+Use `git mv` for each file so history is preserved:
+```
+git mv .scratch/<slug>/issues/01-foo.md docs/issues/<next>-foo.md
+```
+
+### 5. Merge PRD
+
+If `docs/PRD.md` does not exist: `git mv .scratch/<slug>/PRD.md docs/PRD.md`
+
+If `docs/PRD.md` already exists: append the feature's Problem Statement and Solution sections under a `## <Feature Name>` heading. Do not overwrite the existing file.
+
+### 6. Merge prd.json
+
+If `docs/prd.json` does not exist: `git mv .scratch/<slug>/prd.json docs/prd.json`
+
+If `docs/prd.json` already exists: merge the `userStories` array from the scratch prd.json into the main one, assigning new sequential ids to avoid collisions. Update all merged stories to `"status": "done"`.
+
+### 7. Move ADRs
+
+If any `.md` files exist directly in `.scratch/<slug>/` (not in `issues/`) that look like ADRs (contain `## Status` and `## Decision`), move them to `docs/adr/` renumbered from the next available slot.
+
+### 8. Delete scratch directory
+
+```
+git rm -r .scratch/<slug>/
+```
+
+If `.scratch/` is now empty, remove it too (it has no meaning without sub-features).
+
+### 9. Commit
+
+```
+git add docs/
+git commit -m "docs: close feature <slug> — graduate to docs/"
+```
+
+### 10. Update ralph default (if needed)
+
+If `scripts/ralph_progress.py` exists and its `DEFAULT_PRD` still points at `.scratch/<slug>/prd.json`, update it to `docs/prd.json`.
+
+## Machine setup reference
+
+Skills are stored in `.agents/skills/` and symlinked into `.claude/skills/`. Both directories are git-tracked so cloning the repo gives you all skills automatically.
+
+**On a new machine (Linux/Mac):**
+```bash
+git clone <repo>
+# Skills work immediately — .claude/skills/ symlinks resolve automatically.
+# .claude/settings.local.json is machine-local (gitignored).
+# Recreate it if you need custom permission allowlists.
+```
+
+**On Windows:**
+```bash
+git clone -c core.symlinks=true <repo>
+# Requires Developer Mode or admin rights for symlink creation.
+# If symlinks didn't resolve, run: scripts/link-skills.sh (or re-run /setup-matt-pocock-skills)
+```
+
+**Codex:** reads `AGENTS.md` at the repo root — already tracked, no setup needed.
+
+**Hermes / other local LLM tools:** add their context files to the repo root or `docs/` and commit. Point the tool at that file in its config.
+
+**To add a new skill to the repo:**
+```bash
+mkdir .agents/skills/<name>
+# write .agents/skills/<name>/SKILL.md
+ln -s ../../.agents/skills/<name> .claude/skills/<name>
+git add .agents/skills/<name> .claude/skills/<name>
+git commit -m "skill: add <name>"
+```