docs(okf): add distilled spec, frontmatter reference, and templates

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

custom-skills/97-ourdigital-okf/code/references/okf-spec-v0.1.md

@@ -0,0 +1,92 @@
+# OKF v0.1 — Authoring Rules & Conformance Checklist
+
+Distilled, actionable reference for producing and validating Open Knowledge Format
+bundles. Authority: the full spec at
+`~/Documents/reference-library/open-knowledge-format/okf/SPEC.md`. **Read this file
+before producing a bundle.**
+
+## Core model
+
+- **Bundle** — a directory tree of markdown files. The unit of distribution.
+- **Concept** — one markdown file = one unit of knowledge (a table, dataset, metric,
+  playbook, API, reference…).
+- **Concept ID** — the bundle-relative file path with `.md` removed
+  (`tables/users.md` → `tables/users`). The path *is* the identity.
+- Concepts form a **graph**, linked by ordinary markdown links — richer than the
+  parent/child implied by the directory tree.
+
+## Reserved filenames (not concepts)
+
+| File | Purpose |
+|------|---------|
+| `index.md` | Directory listing for **progressive disclosure** (§6). No frontmatter — except an optional bundle-root `index.md` may carry `okf_version: "0.1"`. |
+| `log.md` | Update history: date-grouped (`YYYY-MM-DD`, newest first), entries lead with a bold verb (`**Update**`, `**Creation**`…). |
+
+All other `.md` files are concept documents.
+
+## Frontmatter
+
+YAML block delimited by `---` at the very top of the file.
+
+| Field | Status | Notes |
+|-------|--------|-------|
+| `type` | **REQUIRED** | Short string, e.g. `BigQuery Table`, `BigQuery Dataset`, `Metric`, `Playbook`, `Reference`, `API Endpoint`. Not centrally registered; consumers tolerate unknown types. |
+| `title` | Recommended | Display name; else derived from filename. |
+| `description` | Recommended | One sentence; used in index snippets/previews. |
+| `resource` | Recommended | Canonical URI of the underlying asset; omit for abstract concepts. |
+| `tags` | Optional | List of short strings (inline `[a, b]` or block `- a`). |
+| `timestamp` | Optional | ISO 8601 last-modified time. |
+| *(extensions)* | Optional | Any extra producer keys; preserve, never reject. |
+
+## Body
+
+Standard markdown. Prefer structural markdown (headings, tables, lists, fenced code)
+over prose. Conventional section headings (use when applicable):
+
+| Heading | Purpose |
+|---------|---------|
+| `# Schema` | Columns/fields of an asset. |
+| `# Examples` | Concrete usage, usually fenced code. |
+| `# Citations` | Numbered external sources backing body claims. |
+
+## Cross-linking
+
+- **Bundle-relative (recommended):** leading `/`, from the bundle root —
+  `[customers](/tables/customers.md)`. Stable when files move within a subdirectory.
+- **Relative:** `[other](./other.md)`.
+- A link asserts an *untyped* relationship; the kind is conveyed by surrounding prose.
+- **Broken links are tolerated** — they may represent not-yet-written knowledge. Never
+  an error.
+
+## Conformance (§9) — what the validator enforces
+
+A bundle is conformant if:
+1. Every non-reserved `.md` has a parseable YAML frontmatter block.
+2. Every frontmatter block has a non-empty `type`.
+3. `index.md` / `log.md` follow their structure when present.
+
+Consumers MUST NOT reject for: missing optional fields · unknown `type` values ·
+unknown extra keys · broken cross-links · missing `index.md`.
+
+Run: `python3 ../scripts/okf_validate.py <bundle>` (exit 0 = conformant; broken links
+are warnings).
+
+## Producer authoring rules
+
+1. **One concept per file.** Choose a directory layout that fits the domain
+   (`datasets/`, `tables/`, `metrics/`, `references/`, `playbooks/`…).
+2. **Always set `type`** — descriptive and self-explanatory.
+3. Add `title` + a one-sentence `description` to every concept (drives indexes).
+4. Set `resource` for concepts bound to a real asset; omit for abstract ones.
+5. **Cross-link** related concepts with bundle-relative links; reference FKs/joins in
+   prose.
+6. Add a `# Citations` section (numbered) whenever the body makes externally-sourced
+   claims; cite as URLs, bundle paths, or `references/<slug>` concepts.
+7. Generate an `index.md` per directory (and the root) listing children with their
+   descriptions, for progressive disclosure.
+8. **Self-validate** before declaring done; fix every conformance error.
+
+## Versioning
+
+`<major>.<minor>`. Minor = backward-compatible additions; major = breaking changes.
+Bundles may declare `okf_version: "0.1"` in the root `index.md` frontmatter.