# Knowledge domain — schema

The knowledge domain is the durable, authoritative current-state documentation of the homelab: one
page per node and per cross-cutting system, synthesized from live state and evidence. It answers
"what exists and how does it work right now."

It follows the [LLM Wiki layer model](../../shared/llm-wiki.md) and the
[writing-style](../../shared/writing-style.md) and [page-templates](../../shared/page-templates.md)
rules.

## The narrative / substrate split

The knowledge wiki is **narrative**. It sits alongside a **machine-readable substrate** that it
describes but never contains. The split is load-bearing: several programs read the substrate at
fixed paths, so the wiki reorganization never moves it.

| Layer | Location | Consumed by |
|-------|----------|-------------|
| Substrate — source of truth | `inventory.yaml` (root) | MCP server, `homelab` CLI, `oikos/` scheduler/drift/relations/gen-topology |
| Substrate — generated host records | `inventory.yaml` (root) | Go `internal/mcp/` server, `bin/homelab`; the single source of truth |
| Substrate — kernel + context cards | `oikos/` (code, `oikos/cards/`, `oikos/state.json`) | MCP `explain`, scheduler |
| Narrative — synthesized wiki | `archive/knowledge/{hosts,containers,vms,infrastructure}/` | humans, agents via MCP `get_page` / `search_docs` |
| Evidence — immutable sources | `knowledge/sources/` (references + investigations) | synthesis into wiki pages |

## Wiki pages

- **Node pages** (`archive/knowledge/containers/<id>-<name>.md`, `.../vms/<id>-<name>.md`,
  `.../hosts/<name>.md`) follow the container/host template in
  [page-templates.md](../../shared/page-templates.md): opening definition, `## At a glance`,
  `## Role`, service/port map, storage, auto-deploy, `## Related`, `## Changelog`.
- **Cross-cutting pages** (`archive/knowledge/infrastructure/<topic>.md`) follow the cross-cutting
  template: `## Why`, `## Components`, `## How to apply`, `## Gotchas`, `## Related`, `## Changelog`.
- Each `inventory.yaml` host entry carries a `doc_page:` field pointing at its narrative page.
  Changing where a page lives means updating that field (read by `bin/homelab`).

## The two logs

- The per-page **`## Changelog`** records infrastructure changes and is machine-parsed
  (`get_changelog`, the Oikos ledger). Keep the `### YYYY-MM-DD — title` shape.
- **`knowledge/log.md`** is append-only and records *documentation-maintenance* operations only
  (restructures, source ingests, lint sweeps): `## [YYYY-MM-DD] <op> | <summary>`. It never
  duplicates the Oikos change ledger (`oikos/ledger.py`).

## Same-session update rule

A change to a node updates every page that references it in the same session — the node page, the
section `README.md` table, the root `README.md`, the Caddy/DNS/ingress pages, the host page, and
`inventory.yaml`. See [page-templates.md](../../shared/page-templates.md#same-session-update-rule).