Phase 1: content source of truth — 40 documents across six areas

Satisfies the Phase 1 Definition of Done:

- content/ validates cleanly against the frozen schema. `make validate`
  reports OK: 40 document(s) validated, 0 violations.
- Six areas exist, each with an L1 entry: ai-overview, platform-overview,
  edge-overview, products-overview, history-overview, about-overview.
- All six areas have an L2 entry: ai-systems, platform-estate, edge-fleet,
  products-business, history-engagements, about-narrative.
- 28 L3 artefact stubs under content/<area>/l3/. Every artefacts[].url in
  every document resolves to one of them; the validator proves there are no
  dangling references (and a deliberately broken copy exits 1).
- Every metric value traces to a source line in the evidence notes or the
  approved metric set in reference/content-map.md (per-metric citations are
  recorded in the AUD-131 completion comment).
- Every document carries confidence and last_verified=2026-10-26; the
  validator rejects a missing or non-canonical value.
- docs/content-redaction.md records the redaction pass: identifiers, third
  party personal data, credentials and infrastructure detail excluded, with
  reasons, plus the two numbers that are reported rather than smoothed.

Honesty positions held: 3 businesses active (12 adoptions over time),
Where-Woof deployed and pre-market, failures kept in (edge-failures), no
promotion of in-progress work to delivered.

No site code, no templates, no CSS, no rendering (Phase 2).

content/platform/l3/platform-nixos.md

@@ -0,0 +1,35 @@
+---
+id: platform-nixos
+area: platform
+level: 3
+title: "Artefact — Declarative multi-host configuration"
+claim: "Machines are described rather than assembled — a shared NixOS base · a replicated desktop and terminal · and Proxmox underneath the virtualised side."
+confidence: running
+period: "2020–"
+tech: [NixOS, Niri, Proxmox, Neovim, Zsh, Ghostty]
+metrics: [{label: "hosts on the declarative base", value: 4}]
+artefacts: []
+public: true
+last_verified: 2026-10-26
+tags: [platform, nixos, artefact]
+---
+
+# Artefact — Declarative multi-host configuration
+
+**Status: stub.** A redacted excerpt of the configuration tree lands in Phase 7. No hostnames, addresses or keys are published.
+
+## What the artefact is
+
+The shape of the configuration: one shared base, per-host modules, and the parts that make the desktop and the terminal identical everywhere — window manager, editor, shell and the plugins that carry the work. Proxmox hosts the virtualised side, including the file server and the home automation appliance.
+
+## What it proves
+
+That a machine can be rebuilt from a description, and that the same environment follows the person between machines instead of being re-created by memory.
+
+## Limits stated on the page
+
+The terminal-first setup is deliberate: a heavier desktop was downgraded to the terminal on one machine for memory headroom. A phone-as-server experiment is on hold, not shipped, and is described as on hold.
+
+## When it is delivered
+
+Phase 7. Source facts: evidence notes section 3.