docs: add hardware-docs editing guide and link it in nav

Add docs/guides/editing-hardware-docs.md covering the frontmatter schema,
rack/shelf/PDU/power/network fields, the `make docs-index` workflow and
CI drift gate, plus dos and don'ts. Kept under docs/guides/ so the
hardware generators don't parse it as a host file. Linked under the
Hardware nav section so it publishes to docs.makerfloss.eu.

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

docs/guides/editing-hardware-docs.md

@@ -0,0 +1,196 @@
+---
+title: Editing the hardware docs
+---
+
+# Editing the hardware docs
+
+The hardware inventory is **one Markdown file per device** under
+`docs/hardware/`. The YAML frontmatter at the top of each file is the single
+source of truth. Everything you see rendered — the
+[Hardware Overview](../hardware/index.md) table, the per-device **Specs** box,
+the [rack elevation](../infrastructure/racks/rack01.md) SVG, and the network
+graph — is **generated** from that frontmatter.
+
+!!! warning "The golden rule"
+    After editing any file in `docs/hardware/`, run **`make docs-index`** and
+    commit the regenerated files. CI rebuilds the indices and fails the build if
+    they differ from what you committed. This is the single most common reason a
+    push goes red.
+
+## Quick start: add a device
+
+1. Pick a hostname following the scheme `<kind-abbrev><NN>` — a 2-digit number,
+   unique per kind (`srv`, `sw`, `pp`, `pdu`, `ups`, `shf`, …). Example: `srv06`.
+2. Create `docs/hardware/<hostname>.md`. **The filename stem must equal the
+   `hostname` field** — `srv06.md` must contain `hostname: srv06`.
+3. Fill in the frontmatter (see the reference below). Write any free-text under
+   `## Notes`.
+4. Run `make docs-index` and commit **both** your new file and the regenerated
+   index / rack files.
+
+```markdown
+---
+hostname: srv06
+kind: server
+status: staging
+location: The pile
+cpu: Intel Core i5-3570K @ 3.40GHz
+cpu_cores: 4
+cpu_threads: 4
+ram_gb: 8
+storage_gb: 500
+storage_type: hdd
+nic_gbps: 1
+rack: rack01
+rack_u: 7
+u_height: 2
+rack_face: front
+power:
+  - { pdu: pdu01, outlet: 5 }
+links:
+  - { local: eth0, peer: sw01, peer_port: 6, speed_gbps: 1 }
+---
+
+## Notes
+
+Donated tower; PSU replaced 2026-06.
+```
+
+## Frontmatter reference
+
+### Required on every device
+
+| Field | Notes |
+|---|---|
+| `hostname` | Must equal the filename stem. |
+| `kind` | One of the enum below. |
+| `status` | One of the enum below. |
+
+**`kind`** — `server`, `laptop`, `sbc`, `switch`, `ap`, `desktop`, `pdu`,
+`patch-panel`, `shelf`, `blank`, `ups`, `kvm`.
+
+**`status`** — `in-use`, `staging`, `spare`, `broken`, `donated`.
+
+### Specs (optional, shown in the table and Specs box)
+
+| Field | Example | Notes |
+|---|---|---|
+| `location` | `The pile` | Free text. |
+| `cpu` | `Intel Core i5-3570K @ 3.40GHz` | Model string. |
+| `cpu_cores` / `cpu_threads` | `4` / `8` | Integers; threads shown only if they differ from cores. |
+| `ram_gb` | `8` | Integer (rendered as `8 GB`). |
+| `storage_gb` + `storage_type` | `500` + `hdd` | `storage_type` ∈ `nvme`, `ssd`, `hdd`, `mixed`. |
+| `storage` | `[{gb: 500, type: ssd}, {gb: 2000, type: hdd}]` | List form for multiple drives (alternative to the two fields above). |
+| `nic_gbps` | `1` or `[1, 10]` | Number or list (rendered as `GbE`). |
+
+### Placement in a rack
+
+Only files that declare a `rack:` appear in a rack elevation. The rack is 48U.
+
+=== "Front / rear (U-mounted)"
+
+    ```yaml
+    rack: rack01
+    rack_face: front     # front | rear | both
+    rack_u: 7            # starting U (1–48)
+    u_height: 2          # height in U (≥1)
+    ```
+
+    `both` occupies the same U range on **front and rear**. Two U-mounted
+    devices may not overlap on the same face.
+
+=== "0U side rail (e.g. vertical PDU)"
+
+    ```yaml
+    rack: rack01
+    rack_face: left      # left | right
+    # no rack_u / u_height
+    ```
+
+    Side-rail (`left`/`right`) items are 0U and **must omit** `rack_u` and
+    `u_height`.
+
+=== "Shelf-mounted"
+
+    ```yaml
+    rack: rack01
+    mounted_on: shf01    # an existing kind:shelf in the same rack
+    shelf_face: front    # front | rear
+    shelf_slot: 2        # integer ≥1
+    # no rack_u / u_height / rack_face
+    ```
+
+    The shelf itself must be placed (have `rack_u` + `u_height`). Two devices
+    can't share the same `(shelf, face, slot)`.
+
+### Power feeds
+
+A device draws power by listing feeds. Each feed must point at a real `kind:pdu`
+file, and the outlet must be within that PDU's `outlets` count.
+
+```yaml
+power:
+  - { pdu: pdu01, outlet: 5 }
+```
+
+A `pdu` device must declare a positive integer `outlets:` (e.g. `outlets: 8`).
+
+### Network links
+
+Links feed the network graph. `peer` is the hostname of a switch / patch-panel
+/ peer device.
+
+```yaml
+links:
+  - { local: eth0, peer: sw01, peer_port: 6, speed_gbps: 1 }
+```
+
+## The make process
+
+| Command | What it does |
+|---|---|
+| `make docs-index` | Regenerate the hardware/services indices and rack elevations from frontmatter. **Run this after every edit.** |
+| `make docs-check` | Regenerate, then fail if the result differs from the committed copies — exactly what CI runs. |
+| `make docs-build` | Build the static site with `mkdocs build --strict`. |
+| `make docs-serve` | Live-reload local preview at `http://127.0.0.1:8000`. |
+| `make test` | Run the Python unit tests (`pytest`). |
+
+A typical edit loop:
+
+```bash
+$EDITOR docs/hardware/srv06.md
+make docs-index          # regenerate
+make docs-check          # confirm no drift (optional sanity check)
+git add docs/hardware/srv06.md docs/hardware/index.md docs/infrastructure/racks/
+git commit -m "hardware: add srv06"
+git push                 # CI builds and publishes to docs.makerfloss.eu
+```
+
+On push to `main`, CI regenerates the indices, runs the drift check, builds the
+site strictly, and publishes it. If you forgot `make docs-index`, the drift
+check fails and nothing is published.
+
+## Dos and don'ts
+
+!!! success "Do"
+    - **Do** run `make docs-index` and commit the regenerated files with your change.
+    - **Do** keep the filename equal to the `hostname`.
+    - **Do** use the `<kind-abbrev><NN>` naming scheme, 2 digits, unique per kind.
+    - **Do** mark unknown values as provisional placeholders and ask before
+      inventing rack/power/network numbers.
+    - **Do** preview locally with `make docs-serve` before pushing.
+
+!!! danger "Don't"
+    - **Don't** hand-edit generated files — `docs/hardware/index.md`,
+      `docs/services/index.md`, `docs/infrastructure/racks/*.md`, and the
+      `*-elevation.svg` files all carry a *"do not edit by hand"* banner and will
+      be overwritten.
+    - **Don't** put non-device Markdown into `docs/hardware/` — the generators
+      scan that folder and expect host frontmatter. Guides like this one live in
+      `docs/guides/`.
+    - **Don't** give a 0U side-rail item (`left`/`right`) a `rack_u`/`u_height`,
+      and don't give a U-mounted item a side-rail face — the generator rejects
+      both.
+    - **Don't** point `power` at a non-PDU, or use an outlet number beyond the
+      PDU's `outlets` count.
+    - **Don't** rename a file without renaming the `hostname` to match.

mkdocs.yml

@@ -59,6 +59,7 @@ nav:
   - Home: index.md
   - Hardware:
       - hardware/index.md
+      - Editing the hardware docs: guides/editing-hardware-docs.md
   - Services:
       - services/index.md
   - Infrastructure: