docs: Chunk 3 issues 0015-0028 and doc updates

14 issues created covering AGENTS.md refactor prerequisite, skill
implementation workflow grill, bootstrap skills (write-eval, write-skill),
remaining factory skills, and one issue per skill category group through
to chunk closure. All HITL; acceptance criteria for 0017-0028 to be
refined after 0016 grill session.

Doc updates: CONTEXT.md PRD/issue scope clarified (HOW distribution
across architecture-review and issue design notes); ROADMAP.md housekeeping
updated with bootstrap order and issue range; spec/overview.md recent
changes entry added; PRD updated (skills-index: delete → update).

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

docs/issues/0018-factory-write-skill.md

@@ -0,0 +1,44 @@
+# 0018 — factory/write-skill (bootstrap skill)
+
+**Type:** HITL  
+**Parent PRD:** `docs/prd/chunk-3-skills-library.md`
+
+## What to build
+
+Build `write-skill` — the second bootstrap skill, immediately after `write-eval`. Once `write-skill` exists, it is used to author all subsequent SKILL.md files in Chunk 3 rather than writing them by hand.
+
+**Trigger description** (from skills index): "Write a new skill for X, create a SKILL.md that does Y"
+
+**Key constraints:**
+- Produces a complete SKILL.md following the authoring standard (frontmatter, role, when/when-not, required inputs, constraints, process, output format, failure handling)
+- Validates trigger description against three test queries (explicit, implicit, negative) before completing
+- Flags if the proposed skill overlaps with an existing skill in the library
+- Skill file: `.agents/skills/write-skill/SKILL.md`; `metadata.category: factory`
+- Origin: new skill (check upstream for prior art during implementation); `source:` populated only if upstream content is adopted
+- Eval via `write-eval` (issue 0017)
+
+Process: upstream review → trigger-first → skill body → `write-eval` for eval.yaml → behavioral test.
+
+## Implementation notes
+
+Follow the per-skill workflow defined in `docs/notes/skill-implementation-workflow.md` (produced by issue 0016).
+
+**Known upstream sources to review:**
+- `mattpocock/skills` — contains `write-a-skill`, the direct Pocock equivalent; review at current HEAD; record SHA in `source:` for any adopted content
+- agentskills.io open standard — the SKILL.md format spec is the authoritative reference for what `write-skill` must produce; cross-reference against the standard before finalising output format constraints
+- `bmad-method/bmad-method` — check for any skill-authoring or template-writing patterns
+
+## Acceptance criteria
+
+- [ ] `.agents/skills/write-skill/SKILL.md` exists; `metadata.category: factory`; authoring standard met
+- [ ] Trigger description validates against explicit, implicit, and negative test queries
+- [ ] `.agents/evals/factory/write-skill/eval.yaml` exists; produced via `write-eval`
+- [ ] `install.sh` deploys `write-skill` to `~/.agents/skills/`
+- [ ] **HITL:** human runs behavioral test: invoke "write a new skill for X" and verify the produced SKILL.md meets the authoring standard
+- [ ] **HITL:** human reviews SKILL.md and eval before committing
+- [ ] _(Further criteria to be refined after issue 0016 grill session)_
+
+## Blocked by
+
+- 0016 (grill defines per-skill workflow)
+- 0017 (`write-eval` needed to produce the eval for this skill)