chemenu/types/type-spec.md

type, name, description, schema

type	name	description	schema
types/type-spec.md	type-spec	Authoring and validation contract for path-valued Chemenu type specifications	types/type-spec.schema.yaml

Type spec

A type-spec doc is the authoring and validation contract for one Chemenu artifact type. Artifact frontmatter stores the repo-relative path to this doc in type:, and this file serves several consumers differently: an author writing a new instance reads it for what to write, someone unfamiliar with the type reads it for what to expect from an instance before opening one, and the validator and the type-conformance reviewer read it to check conformance.

Contents

• Required Frontmatter
• Validation Contract
• Writing Shape
• The type layer
  • Who owns a type-spec
  • Anatomy of a type
  • Placement frontmatter
  • Adding a type
  • Template variables
  • Ownership boundary
  • What does not belong here
• Template

Required Frontmatter

• type: types/type-spec.md. The root type spec is self-referential and uses the same value.
• name: short human-facing type name. This is also the type's logical "kind" - tooling resolves an instance's type: path to this name instead of hardcoding a type-path-to-kind mapping.
• description: retrieval description for the type contract.
• schema: repo-relative path to the .schema.yaml file that validates artifacts of this type, or null when the type has no schema.
• subtype_field (optional): the frontmatter field name on instances of this type that carries a subtype/category (e.g. entity_type), or omitted if this type has no such field.
• guidance (optional): repo-relative path to a types/type-guidance.md-shaped document holding this type's stack-owned authoring prose - see § "Anatomy of a type" below. Meaningful only on a root: kb type-spec; omit for a type an instance writes entirely for itself.

Validation Contract

Two systems check conformance to a type:

• The deterministic validator checks the symbolic half: frontmatter fields, enums, path patterns, and syntactic body shape (required headings, section counts, date formats) — whatever the named .schema.yaml can statically specify. It parses structure; it never judges meaning.
• The type-conformance review gate checks the semantic half: everything about an instance that is not mechanically checkable — a description's routing quality, a title's claim-shape, whether the body's claims hold up — judged against this file's body, read as natural-language authoring instructions applied by an LLM reviewer.

Do not restate a schema rule in body text. The validator already enforces it, so the restatement adds no protection — it only spends the reviewer's judgment re-confirming something already guaranteed, instead of on the properties only a reviewer can check.

Writing Shape

• Write the body as a content contract: checkable properties of a conforming instance, in a form the type-conformance gate can apply directly. Prefer "what a conforming instance contains or claims" over "how to produce one" — production process is invisible to the reviewer, so it belongs in a skill or instruction, linked rather than embedded.
• State what the type is for and when an author should choose it over a neighboring type.
• Document the frontmatter fields (required and optional) as a reference for authors; the schema is the sole source of truth for requiredness.
• When schema is non-null and implies body structure beyond type/name/description, include a ## Template an authoring agent can copy.

The type layer

types/ is the repo's global type surface: one set of type-specs serving every collection under kb/. It is deliberately not a collection and carries no COLLECTION.md — there is no per-collection type surface, and tools/wikitool docs verify fails if a contract appears here.

Who owns a type-spec

types/ holds two kinds of file, and the line between them is root: — already in the frontmatter before anyone drew it:

Type-spec	Describes	Owned by	Ships as
root: kb (entity, concept, source, comparison)	A page this instance writes	The instance	types/<name>.md.template plus its .schema.yaml.template, adopted by a rename
root: repo (instruction), no base_dir (lint-report), and type-spec/type-guidance themselves	A stack artifact	The stack	Verbatim

A page type-spec's frontmatter configuration and its ## Template body are therefore the instance's to rewrite, and an upgrade does not take that back. Its generic authoring prose is the opposite: where the type-spec declares guidance:, that prose lives in a separate, stack-owned types/<name>.guidance.md (§ "Anatomy of a type" below) that ships verbatim and is overwritten by an upgrade like any other machinery file - the type-spec it documents does not have to be re-adopted, or even touched, for that improvement to arrive. A type-spec that declares no guidance: (a type an instance writes entirely for itself) has no stack half to receive; it is described from its own body alone, exactly as every type-spec worked before this split existed. An existing instance that adopted its type-specs before guidance: existed takes this as an offered migration (instructions/CONTRACT.md) rather than something an upgrade applies on its own - see instructions/migrations/ for the document.

Ownership and language still do not line up with each other, and that stays true even though the authoring prose now has its own file rather than sharing one with the template. Owning the type-spec means the instance may rewrite its frontmatter and its ## Template body; a guidance file it links is never the instance's to rewrite at all - it is the stack's, the same way tools/CONTRACT.md is. What each part is written in still follows what the line is for, per AGENTS.md § File naming, independent of which file it lives in or who owns that file:

Part of a root: kb type's contract	Lives in	Audience	Language
When to use / not to use, authoring guidance	The guidance: file, where declared	An agent writing a page	The control plane's — English
The frontmatter table documenting this instance's own fields	The type-spec itself	An agent writing a page	The control plane's — English
The ## Template body, and the layout: titles that head a catalog section	The type-spec itself	The page itself	The instance's KB language (kb/CONVENTIONS.md language:)
Field names, enum values, dir: values, type: paths	Either file's frontmatter	The machine	Neither — identifiers, never translated

That is the same prose/identifier cut kb/CONTRACT.md makes inside a page, applied one level up. It binds a type-spec an instance writes for itself exactly as it binds the four shipped ones: a new page type is instance-owned end to end, which settles who may change it, not which language each half is written in - and it may declare its own guidance: file if it wants the same shape, though nothing requires it to.

What the stack still requires of the type layer is one line. There must be a type-spec declaring name: source whose schema requires raw_files: — the whole raw/ → kb/ provenance path (sources coverage, [^cite-id] resolution, kb/provenance.md) asks page.kind == "source", so without it nothing resolves. docs verify checks exactly that and nothing beyond it: not the directory, not the title prefix, not a word of the prose. Which collection is stack-required is derived from where that type writes rather than listed separately, so renaming it stays consistent instead of tripping a hardcoded name.

Quality goal: a type-spec is the single source of truth for its type. No structural fact about a page type may be restated anywhere else — not in AGENTS.md, not in a skill, not in Python. Adding a type must require no code change.

Anatomy of a type

Each type is at least two files, and a root: kb type may be three:

File	Owns
types/<name>.md	This instance's configuration: its frontmatter fields as this schema requires them, and the ## Template block used to scaffold new pages. For a type with no guidance: (below), its own prose also carries the authoring contract - when to use the type, when not to
types/<name>.schema.yaml	The machine-checkable half: fields, types, enums, defaults, required-ness, additionalProperties: false
types/<name>.guidance.md (optional, root: kb only)	The stack-owned authoring contract: when to use the type, when not to, and mechanism-level advice that holds regardless of this instance's own enum values or template text - linked from the type-spec's own guidance: field. types/type-guidance.md is its contract

This file is the self-referential root contract every type-spec is validated against, and type-guidance.md is validated against it the same way lint-report.md is - itself a non-instantiable, contract-only type. tools/wikitool types describe <name> composes all of a type's files into one answer regardless of how many there are; an agent asking for a type's contract never needs to know it came from more than one file.

Placement frontmatter

Beyond the required fields above, a type-spec declares where its instances are written. Never choose a directory by hand - root plus base_dir plus layout decide placement, and tools/wikitool new writes the file.

Field	Required	Use
base_dir	Yes for instantiable types	Directory where instances are written, e.g. entities. Relative to the root named by root:
root	No	Which root base_dir resolves against: kb (default, config.KB_DIR) or repo (config.ROOT)
layout	No	Maps each subtype to its dir and index title
title_prefix	No	Prepended to the page title, e.g. Source -
page_ref_fields	No	Fields whose entries are page titles, e.g. [related, sources]. lint checks they resolve; rename/rm rewrite them

root: kb is the default because it is what every knowledge type wants, and because keeping placement kb-relative is what lets a test point config.KB_DIR at a fixture and be certain nothing can write into the real kb/. root: repo is opt-in, for types whose artifacts are legitimately not knowledge: instruction is the worked example - an agent-directed procedure under instructions/, outside the raw/ -> kb/ provenance rules entirely.

layout is what turns a subtype field into areas, and it is optional in both directions on purpose. Declaring one makes every instance land in a directory named by its subtype and gives that directory its index title; leaving it off keeps the collection flat, however many subtypes the schema allows (comparison is the worked example - it has no subtype_field at all, so there is nothing for a layout to key on). The choice for a type that does carry a subtype field is whether the split helps: the catalog shards per area, so areas are how a large collection stays readable, but a field whose values are lopsided - one dominant value plus a handful of rare ones - would produce one big area and a scatter of splinters, which is not an improvement. wikitool lint's unsharded_collections finding says which case a collection is in once it grows past the shard threshold, and whether a layout: is already declared for the split it recommends.

A lopsided field is a reason to fix the field, not a reason to leave layout off forever - source was exactly this case: 25 of 29 pages carried one value because the schema handed out that value as a default whenever nobody chose one, not because the material was genuinely that uniform. Once the default was removed and the pages reclassified by what they actually were, the field split into six areas with none of them small. Declare layout for every enum value once it does: a value missing from it still gets a directory (subtype_dir falls back to naively pluralizing the value's own name), but that directory carries no title in wiki/index.md, which is a silent gap rather than a deliberate flat collection. Leaving a whole type's layout off is for the case in the paragraph above - no subtype field to key on at all

• not for a subtype field one has simply not gotten around to mapping. A dir: must be a single path segment, because an area is as deep as a page goes.

A type-spec without base_dir is a contract only and cannot be instantiated; wikitool new <name> refuses it. lint-report is the worked example: its artifacts are generated into reports/, so it describes a file format without owning a place anything writes to.

Adding a type

1. Write types/<name>.md with the frontmatter above and a ## Template fenced block.
2. Write types/<name>.schema.yaml declaring every field, with additionalProperties: false.
3. Confirm it is discovered: tools/wikitool types list, then tools/wikitool types describe <name>.
4. Scaffold with tools/wikitool new <name> --name "..." --set field=value.

No Python change is needed at any step; wikitool discovers types by scanning this directory.

Template variables

The ## Template block is filled from the page's own frontmatter, plus {name} and {today}. Filters render structured fields: {entities|bullets}, {tags|join}, {entity_type|capitalize}, {entities|table_header}, {entities|table_sep}, {entities|table_cells}. {field|literal text} falls back to the literal when the field is absent.

A template never contains a tool-owned region. The links and footnotes regions are generated between markers by xref and cite, rendered from frontmatter, and re-rendered on every write - so scaffolding them would create a section an author is forbidden to edit and the tool would replace anyway. See tools/chemenu/blocks.py.

Ownership boundary

Owned here	Owned by kb/CONTRACT.md	Owned by kb/CONVENTIONS.md and the collection contracts
Frontmatter fields, enums, defaults, required-ness	Provenance and citation mechanics	Quality goal and tone
Directory placement and title prefix	Linking mechanics and the orphan check	Naming conventions
Body skeleton (template)	The prose/identifier rule	Relationship vocabulary
When to use / not use this type	—	The KB language value, and its section-heading names

If a rule would be identical for every type and every instance, it belongs in kb/CONTRACT.md. If every instance would answer it differently, it belongs in kb/CONVENTIONS.md. If it is identical for every page in one collection, it belongs in that collection's COLLECTION.md.

What does not belong here

• Page instances. Nothing under types/ is content.
• A COLLECTION.md. types/ is a framework surface, not a collection.
• Anything already enforced by a .schema.yaml restated in prose as if it were separately authoritative.

Template

---
type: types/type-spec.md
name: {type-name}
description: "{Retrieval description for this type contract}"
schema: {types/{type-name}.schema.yaml or null}
---

# {Type name}

{What this type is for, and when to choose it over a neighboring type.}

## Frontmatter

| Field | Required | Use |
|---|---:|---|
| `type` | Yes | `{this type spec's own repo path}` |
| `name` | Yes | {short human-facing type name} |
| `description` | Yes | {retrieval description for instances of this type} |
| `schema` | Yes | {repo-relative path to schema.yaml or null} |

## Template

```markdown
{a copyable frontmatter + body skeleton matching the schema}
```

---

Relevant Notes:

• This is the root type-spec that all other type-specs reference
• Type-specs form the structural backbone of the wiki's type system
• All validation flows through type-spec definitions