houseplan-card/docs/ARCHITECTURE.md

# House Plan architecture

Updated: 2026-07-04 (v1.2.2). The repository = a HACS integration (category **Integration**)
that contains both the backend (`custom_components/houseplan`) and the Lovelace card (`src/` → `dist/`).

## Layout

```
houseplan-card/
├─ src/                          # card sources (TypeScript + Lit 3)
│  ├─ houseplan-card.ts          # the card: rendering, states, drag, tooltip, sticky header
│  ├─ editor.ts                  # GUI config editor (ha-form + selectors)
│  ├─ rules.ts                   # icon rules (iconFor), filtering, groups, domain priority
│  └─ data/
│     ├─ house.ts                # geometry: ROOMS (rooms→area), FLOOR_VB (viewBox), names
│     └─ backgrounds.ts          # VECTOR plans (SVG base64) + FLOOR_BG_RECT (positioning)
├─ dist/houseplan-card.js        # build (rollup+terser), ~290 KB, plans embedded
├─ custom_components/houseplan/  # the HA integration
│  ├─ __init__.py                # setup: Store, WS commands, JS serving (add_extra_js_url)
│  ├─ websocket_api.py           # houseplan/layout/get|set|update
│  ├─ config_flow.py             # single entry; admin_only option (editing restricted to admins)
│  ├─ const.py                   # DOMAIN, STORAGE_KEY, VERSION, FRONTEND_URL
│  └─ frontend/houseplan-card.js # copy of dist, served as /houseplan_files/houseplan-card.js
├─ hacs.json                     # HACS manifest
└─ docs/                         # this documentation
```

## Key decisions

1. **One repository — integration + card.** The integration serves the JS
   (`async_register_static_paths`) and registers it as a **Lovelace resource** (module) —
   the frontend waits for resources before rendering, so the card also works on a cold start
   of the mobile app (unlike `add_extra_js_url`, which remains a fallback for
   YAML mode). The user does not need to add the resource manually.
2. **Icon layout lives on the server.** `helpers.storage.Store(1, "houseplan.layout")` →
   `.storage/houseplan.layout`. The card reads/writes via `hass.callWS`
   (`houseplan/layout/get|set|update`). Fallback — localStorage (when the integration is absent).
3. **No token.** Everything comes from the frontend `hass` object: `hass.states` (reactive),
   `hass.devices/entities/areas` (registries). No direct WS connections.
4. **Reactivity.** Every state change in HA leads to set hass → re-render.
   Temperatures/LQI/on-off are live by definition (verified by substituting state).

## Coordinate system

- Base space: **1489×1053** ("pixels" of the old PNG render, 1 unit = 1 px).
  All rooms, icon positions and floor viewBoxes live in it. DO NOT change without a layout migration.
- Vector plans are inserted as `<image href=svg>` into the `FLOOR_BG_RECT` rectangle:
  - f1: scale **0.647**, offset **(490, 27)** → rect [490, 27, 774.2, 949.3]
  - f2: scale **0.896**, offset **(351, 21)** → rect [351, 21, 1048.4, 961.4]
  - computed via raster correlation (cv2.matchTemplate on binarized darkness maps) of the
    SVG render against the reference PNG; accuracy ~1 px. The scripts are reproducible (docs/DEVELOPMENT.md).
- Rooms (`ROOMS`) are snapped to the inner faces of walls (semi-automatic: search for the nearest
  "dark line" along the profile + manual fine-tuning against overlay renders).

## Card data model (runtime)

`DevItem`: id (device_id), name, model, area, floor, icon, entities[], primary (the entity used for
more-info by domain priority), temp, members[] (light group), link/linkPrimary (Z2M group).

Built from the registries (`_buildDevices`), rules carried over 1-to-1 from the prototype:
- only devices with an area from the room list are shown;
- hidden: entry_type=service, integrations from EXCLUDED_DOMAINS, model=Group, scenes, bridges,
  myheat sub-devices, duplicates by "name|area";
- **a device with a `lock.*` entity always gets `mdi:lock`** (TTLock locks in the registry
  are named "Dom"/"Terrasa"/"Kladovka" [House/Terrace/Storeroom] — unrecognizable by name);
- lamps (mdi:lightbulb) with ≥2 in a room collapse into a group `mdi:lightbulb-group`
  (click → menu: the whole group + individual lamps).

## Live data

- Temperature: an entity with device_class=temperature / °C / `_temperature$` → label on the right.
- LQI (zigbee): the average over `*_linkquality` entities → label under the icon; color via
  `lqiColor()`: ≤40 red → ≥180 green (hsl gradient). The room average is shown in the room tooltip.
- Icon state classes: on (yellow), open (orange: cover/valve/lock/binary_sensor
  of problem classes), unavail (transparency).

## Sizes

`icon_size` in the config = **% of the visible plan area width** (default 2.5). Implementation:
`.stage { container-type: inline-size }` + sizes in `cqw`. Legacy px values (>8) are ignored.

## Sticky header

`.head { position: sticky; top: var(--header-height, 56px) }`; it is MANDATORY that
`ha-card { overflow: visible }` — `overflow: hidden` breaks sticky.

## Device markers (v1.6.0+)

Per-marker appearance (v1.22.0): `display: badge|ripple|icon_ripple` (+`ripple_color`,
`ripple_size`) draws presence-style pulsing rings gated by the pure `isActiveState` —
deliberately independent of the card-wide `live_states` toggle, with `unavailable` counting as
idle. `size` (icon multiplier via the `--dev-size` CSS var — value badges scale along) and
`angle` rotate/scale a single icon. Room drawing shows a live **ruler** (`segmentCm` +
`formatLength`, metres or feet+inches by `hass.config.unit_system`); the scale is per-space
`cell_cm` (default 5 cm per grid cell).


`config.markers[]`: `{id, binding:'device:<id>'|'entity:<eid>'|'virtual', space?, area?, hidden?,
name?, icon?, model?, link?, description?, pdfs:[{name,url}]}`. A hybrid: auto-discovered HA devices
appear on their own; a marker with `binding=device:<id>` overrides them (metadata/rebinding/hiding),
`entity:<eid>` — for groups/helpers, `virtual` — a manual icon without HA. The marker id = device_id /
`lg_<eid>` / `v_<rand>` (preserves the position in the layout). The binding picker excludes already-placed
references and duplicates by name|area. Manual files: transactional HTTP upload into `<config>/houseplan/files/<id>/`
(staging `up_*` folders promoted on save), served via signed
`/api/houseplan/content/files/…` urls.

## Server-side configuration (current shape, v1.51+)

`.storage/houseplan.config` (Store):
```json
{ "spaces": [{ "id","title","plan_url","plan_aspect","view_box":[4],
               "rooms":[{"id","name","area","poly|x/y/w/h","open_to","settings"}],
               "openings":[…], "decor":[…], "settings":{…} }],
  "markers": [{ "id","binding":"device:<id>|entity:<eid>|virtual","hidden",
                "name","icon","display","controls","is_light","tap_action",
                "room_id","pdfs",… }],
  "settings": { "exclude_integrations":[], "group_lights":true,
                "filter_seeded":true, "fill_colors":{…}, "icon_rules":[…],
                "known_devices":[…], "new_device_ids":[…] } }
```
All coordinates are **normalized (0..1 of the canvas)**; the canvas is always
**square** (v1.48.0), render space `NORM_W × NORM_W` (1000×1000). A space has no
proportions of its own — `plan_aspect` is the IMAGE's ratio, used to letterbox
it centred on the square. The schema bounds geometry to ±4 with strictly
positive sizes (HP-1501/1502). `device_overrides`/`virtual_devices` are long
gone — markers carry everything, `marker.hidden` is the explicit
"hide from plan" flag seeded once by the old filter (docs/FILTERING.md).
Layout v2: `{device_id | rl_<roomId>: {"s": space, "x", "y"}}` (normalized,
bounded ±4). Plan files: `<config>/houseplan/plans/<space>.<token>.<ext>`
(copy-on-write, never overwritten), served via signed
`/api/houseplan/content/plans/_/<name>` urls; growth is bounded by store
quotas, nothing is ever deleted for being old (docs/SCOPE.md).

## Room geometry rules (v1.19–v1.21)

A **line is never an entity of its own**: walls are *derived* from room outlines
(`roomEdges`, deduped by `segKey`), so an abandoned outline leaves nothing behind and deleting
a room keeps the walls its neighbours still contribute. Rooms may not overlap
(`pointStrictlyInside` + `roomsOverlap`; being ON a shared wall is legal — real neighbouring
walls overlap collinearly rather than match exactly). **Merge/Split** use boolean geometry from
**polyclip-ts** (chosen over `polygon-clipping`, whose ESM build exports only a default while
its types declare named exports — breaking either tsc or the runtime): merge accepts a pair only
when the union collapses into one hole-free outline; split cuts wall-to-wall with a chord, the
bigger part keeps the room identity (name/area/devices).

## Markup editor (v1.4.0+)

State inside the card: `_markup` (mode), `_tool` (draw/delroom), `_path` (the current outline,
vertices on the GRID_N=240 grid). Clicks on the stage → `_svgPoint`→`_snap`. The outline is closed
= a click on the first vertex → area select (hass.areas) + name → room {poly}. Polygon rooms and
rectangles are rendered uniformly (hit-test: point-in-polygon / rect).

**A line is never an entity of its own (v1.19.0).** Nothing is persisted while you draw: an
outline you never close leaves no trace. Walls are *derived* from the room outlines by
`roomEdges(rooms)` (logic.ts) and deduped by `segKey`, so a wall shared by two rooms is emitted
once — deleting a room therefore keeps the borders its neighbours still contribute and drops the
rest, with no bookkeeping. The legacy `space.segments` array is stripped on every save (validation
still tolerates it on read; see CHANGELOG v1.19.0).

While drawing, the length of the current segment follows the cursor (`_fmtLen` → `segmentCm`/
`formatLength`): metres, or feet+inches when `hass.config.unit_system` is imperial. The scale is
per-space `cell_cm` — cm represented by one grid cell (default 5, so 240 cells ≈ 12 m).

## Doors & windows (v1.23.0+)

`space.openings[]` — plan geometry, **not** markers: an opening needs an angle, a length and a
wall, while markers are free points whose positions live in the layout store. Model:
`{id, type: door|window, x, y, angle, length, contact?, lock?, invert?, flip_h?, flip_v?}`
(normalized coords; `length` normalized by plan width). Placement snaps onto the nearest
**derived** wall via `snapToWall` (logic.ts) — the angle is normalized to [-90, 90) because two
rooms share a wall with opposite edge directions, and without that a drag across segment
boundaries flips the hinge. The opening then keeps **absolute coordinates**, so editing, merging
or deleting rooms never breaks it.

Rendering (after easy-floorplan, MIT): SVG symbol at the origin (jambs + hinged leaf + a
quarter-circle arc revealed via `stroke-dashoffset`), translated/rotated onto the wall; windows
are two casement leaves. `openingAmount` (pure) maps the contact state to 0..1: no sensor →
door drawn open / window closed (static-plan convention); `unavailable`/`unknown` freeze that
default. The lock renders as an HTML padlock badge (`.oplock`) in the device layer; a lock is
**never** toggled from the plan (TOGGLE_FORBIDDEN_DOMAINS rule). View-mode UX: hover outline,
drag along walls (continuous re-snap, saved on release), click → status card (250 ms timer),
double click → properties dialog. In markup mode the "Opening" tool handles clicks instead.

## Integration WS API

| Command | Parameters | Response |
|---|---|---|
| `houseplan/layout/get` | — | `{layout: {device_id: {x,y}}, rev}` |
| `houseplan/layout/set` | `layout`, `expected_rev?` | `{ok, rev}` / err `conflict`; event `houseplan_layout_updated` |
| `houseplan/layout/update` | `device_id`, `pos` | `{ok, rev}`; event `houseplan_layout_updated` |
| `houseplan/config/get` | — | `{config, rev}` |
| `houseplan/config/set` | `config`, `expected_rev?` | `{ok, rev}` / err `conflict`; event `houseplan_config_updated` |
| `houseplan/plan/set` | `space_id`, `ext` (svg/png/jpg/webp), `data` (b64, ≤8 MB) | `{ok, url}` — writes `<space>.<token>.<ext>`, deletes nothing |
| `houseplan/plans/list` | — | `{plans: [{name, url, size, modified, used_by}], total}` (newest 60) |
| `houseplan/plans/delete` | `name` | `{ok, removed}` / err `in_use` |
| `houseplan/layout/delete` | `device_id` | `{ok, rev}`; event `houseplan_layout_updated` |
| `houseplan/geometry/repair` | `space_id`, `aspect`, `dry_run?`, `undo?` | preview / `{ok, rev, moved}` / `{restored}`; errs `nothing_to_repair`, `no_backup` |
| `houseplan/files/migrate` | `from_id`, `to_id` | `{mapping}` — COPY, never move |
| `houseplan/files/cleanup` | `marker_id`, `keep?` | replacement-only collection |
| `houseplan/content/sign` | `paths[]` | `{urls}` — authSig for `<image>`/`<a>` fetches |

Manual attachments upload over HTTP (streaming, transactional staging), not WS —
the old `houseplan/file/set` was removed in v1.10.0.

**If the v1.48 migration crashed halfway** (HP-1500-01): the config write
landed, the layout write did not, and both triggers are gone — markers of that
space sit in the old coordinates and nothing in the data can prove it. The
`geom_pending` intent (v1.50.0) prevents this for any future migration, but
cannot help an install that was already stranded. There is no safe automatic
answer — re-transforming a layout that is actually correct would corrupt it —
so the fix is explicit: `houseplan/geometry/repair {space_id, aspect}`
re-applies the transform to that one space's positions. `dry_run: true`
previews, the previous positions ride the same store write as a one-deep
backup, and `undo: true` restores them. Admin-gated like every other write.

**The canvas is square, the image is not** (v1.48.0). A space used to carry an
`aspect`, and coordinates were normalised against it — x by the width, y by the
height. That made every geometric question depend on a per-space number for no
benefit. Now the render space is `NORM_W × NORM_W` and a plan image is fitted
inside it by its own ratio (`fitInSquare`, shared by both renderers), which is
stored as `plan_aspect` so the layout does not jump before the file loads.
Upgrading runs `geometry_migration.migrate_config` once: it pads the old box out
to a square and re-expresses every coordinate against it — a uniform scale plus
an offset in render units, so angles and proportions are exact — and scales
`cell_cm` for tall plans, since the grid pitch is a fraction of the width.

**User content is served inert** (HP-1454-01). An uploaded SVG is the only
thing here that a browser will happily treat as a *document* rather than an
image, and it would be a document of Home Assistant's own origin. Inside the
card that never matters — `<image>` does not run scripts — but the url is
reachable directly, and uploading needs only write access, which by default
every user has. `HouseplanContentView` therefore sends a `sandbox` CSP with SVG
and only with SVG: a CSP on a PDF response can break the browser's built-in
viewer, and a raster image has no execution model to disable.

**Attachments follow the same commit-scoped lifecycle as plans** (HP-1454-02).
An upload takes a free name and never overwrites, because the bytes under an
existing name may be referenced by the stored configuration and an upload is
not part of that transaction. `reserve_filename` *claims* the name as it picks
it (`O_CREAT | O_EXCL`) — asking `exists()` and returning a string let two
uploads agree on one name and quietly overwrite each other. It also budgets the
length so the result survives the sanitiser the content view applies to the
request, since a name the view rewrites is a file written and never served.
Streaming temporaries live in the files root under `.upload-`, are removed on
every exit path of the request (including cancellation, which is a
BaseException and slips past `except Exception`), and are swept at startup and
daily. That scheduled pass also runs the two collectors with the stored
configuration as *both* sides — nothing superseded, so every referenced file is
kept and only aged unreferenced ones go. Without it, collection would only ever
happen when somebody saves, and a file uploaded into a dialog that was then
cancelled would wait for a write that may never come. A new icon has no id yet, so its
files go to a per-dialog staging folder and move to the real id once the config
write is accepted — the same copy → save → cleanup order as a rebind.
`config/set` collects what its commit superseded — that much a commit knows for
certain. *Unreferenced* is a far weaker signal, and the policy follows from one
asymmetry: **a few unnecessary megabytes can always be removed by hand; a file
we should not have removed cannot be brought back.** When the evidence is weak,
keep the file. Owner's decision, 2026-07-28, after the one-hour rule applied to
every unreferenced file destroyed two detached plans.

The classification is by **owner**, not by "is it referenced". A file leaving
the configuration looks identical whether the plan was replaced, detached, or
its space deleted — and only the first is a deletion the user asked for. Reading
`old_refs - new_refs` and calling it "superseded" deleted a plan the moment it
was detached, under documentation promising the opposite (HP-1465-01).

| Case | What it means | Rule |
|---|---|---|
| Space in both, plan A → plan B | the user picked another image | removed immediately |
| Space in both, plan → none | detached; one click undoes it | **kept** |
| Space gone | deliberate, but the image was imported and may be nowhere else | **kept** |
| Space has a plan, plus another file of its own | an upload whose save was rejected | **kept** — ageing these out raced the retry that referenced them |
| Marker in both, attachment dropped from its list | a trash button, promising nothing | removed immediately |
| Marker gone | same call as a deleted space's plan | **kept** |
| Attachment in `up_*` | a dialog that was never saved; no device owns it | `PLAN_ORPHAN_TTL_S` (1 h) |
| Marker there, file it never listed | a rejected upload | **kept**, same reason |

Nothing is deleted for being old, with one exception: a per-dialog staging
folder (`up_*`), which by construction can only hold an upload from a dialog
that was never saved. The disk therefore stays bounded by the user, not by a
timer — `houseplan/plans/list` shows every stored plan with its size and which
space uses it, and `houseplan/plans/delete` removes one on request, refusing
while a space still references it. That listing is what makes "we never delete"
livable: a detached plan is not lost, it is one click away in the space dialog.

**Config writes are serialized** (HP-1454-03). `_writeConfig()` chains onto a
single promise: one `config/set` in flight, each carrying the revision the
previous one returned. The debounce still spaces out *when* a write starts;
what it cannot do — and used to be relied on for — is keep two writes from
overlapping, which produced a self-inflicted conflict and lost the newer edit.

**Plan uploads are copy-on-write, and collection belongs to the commit**
(reviews R2-1, R3-1). The file system is not part of the config's
optimistic-locking transaction, so nothing referenced may be overwritten or
deleted before the CAS succeeds: the upload writes a new versioned name and
removes nothing. Deciding what may then go is *not* a client's call — a cleanup
request cannot be ordered against another client's commit, and a delayed one
deletes a plan that was just saved. So `config/set` collects itself, inside its
write lock, from the pair of configurations that bracket the commit
(`plans.collect_plans`): a file the commit REPLACED goes immediately, and
nothing else goes at all — see the table above; only a per-dialog staging folder
ages out. Growth is bounded at the door instead, by `plans.check_quota` on every
upload (store size, file count, free disk), because a limit that deletes is how
plans were lost twice. The `.` between id and token is load-bearing —
a space id cannot contain one, so `<space>.<token>.<ext>` can never be confused
with the files of a space whose name merely starts the same way.

**An internal plan url must exist when it is stored** (HP-1470-02). The picker
can attach a plan and then delete it, and two clients can do the same in either
order — the write lock orders the requests but says nothing about whether the
file survived. `config/set` therefore checks every `/api/houseplan/content/plans/`
url against the disk before saving, and refuses with `missing_plan`. External and
legacy urls are the user's own and are never second-guessed.

**Signed content urls are batched, aged and deduplicated** (reviews R2-2, R3-2, R4-2). `ContentSigner`
in `src/signing.ts` is the single implementation, used by both cards; the
duplicate inside houseplan-space-card signed correctly and never handed the
result to its renderer, which is the failure mode a second copy invites. `MAX_SIGN_PATHS`
(200) is a shared contract between `logic.ts` and `const.py`: the backend caps a
request there and says nothing about the rest, so the card must chunk. Cached
signatures carry the time they were issued — an aging one keeps rendering while
its replacement is fetched, an expired one is dropped rather than served (it
would 401 and raise a failed-login warning). The cache is pruned to the urls the
live config references, so it cannot grow past the cap through history alone.
Queued and in-flight are distinct states: a render happening while a request is
out must not queue the same url again, a failure backs off rather than retrying
on the next frame, and an in-flight entry expires after `SIGN_INFLIGHT_MS` so a
promise that never settles cannot block retries forever.

**Room climate is one pass per hass snapshot** (review R2-3). `areaClimateMap()`
classifies the whole registry once and returns `Map<area, {temp, hum}>`; the
card memoizes it on `hass` identity, which Home Assistant replaces on every
state change. Per-room lookups are O(1). `areaClimate()` survives as a
single-area wrapper for tests — using it in a render reintroduces the
O(rooms × entities) cost it was extracted from.

**File uploads go over HTTP** (not WS, which has a message-size limit): `POST /api/houseplan/upload`
(multipart: marker_id + file), HomeAssistantView, requires_auth. Served from `/houseplan_files/files/`.


## Second card: houseplan-space-card (read-only, v1.16.0)

The bundle registers **two** custom elements from one entry (`src/houseplan-card.ts`
imports `./space-card`):

- `houseplan-card` — the full interactive card.
- `houseplan-space-card` — a static, read-only schematic of ONE space for embedding.

Shared, framework-light modules keep the two views from diverging:

- `src/space-geometry.ts` — pure model/position math (`spaceModels`, `roomBounds`,
  `roomCenter`, `defaultPositions`, `markerPos`, `labelPos`; no Lit import) — unit-tested,
  mirrors the full card's private geometry.
- `src/space-render.ts` — `renderSpaceStatic()` draws the plan + configured room
  borders/names + device markers (via `buildDevices`, same filtering) with NO handlers,
  NO live states, NO status/temperature fills. Uses the same CSS classes as the full card
  (the space-card imports `cardStyles`) for visual parity.
- `src/config-store.ts` — module-level `{config, rev, layout}` cache shared by all embedded
  cards (dedupes `houseplan/config/get`), seeded synchronously from the full card's
  localStorage snapshot (`houseplan_card_cfg_v1`) and invalidated on `houseplan_config_updated`.

**Static contract:** the schematic layer (`.hp-static-stage`) is `pointer-events:none`; the
footer button lives outside it and stays clickable.

**Deep-link contract:** the footer button calls `navigate(button_target + "#space=<id>")`
(default target `/plan-doma`). The full card reads `#space=<id>` on load (a valid id wins over
`default_floor`) and on `hashchange`, without blocking manual space switching; an invalid/absent
hash falls back to the default.


## Additions v1.28–v1.41 (2026-07-24)

- **Decor layer** (`space.decor[]`, v1.33): purely visual shapes
  (line/rect/ellipse/text, normalized coords, per-shape style) drawn in the
  SVG right above the background image and BELOW rooms; pointer-events only
  inside the Background editor. Validated by `DECOR_SCHEMA` (vol.Any of the
  four kinds).
- **Glow fill** (v1.35+): `fill_mode: 'glow'` paints every room with
  `fill_colors.glow_base` and renders per-source radial gradients clipped by
  a per-light `clipPath` = zone polygons + doorway sectors, each contour a
  SEPARATE clipPath child (children union; subpaths of one nonzero path
  cancel on opposite windings — field bug v1.36.3). Radius: global
  `settings.glow_radius_cm` + per-marker `glow_radius_cm`.
- **Open boundaries** (v1.37): `room.open_to: [roomId]` symmetric links;
  light zones are connected components (`openZoneOf`); shared stretches
  computed by collinear-overlap math (`sharedBoundary`) and drawn as a TRUE
  dash — both room outlines and derived wall segments are trimmed
  (`outlineWithout`/`cutSegments`).
- **Marker controls** (v1.36): `marker.controls[]` (lights/switches only)
  toggled as one HA-group-semantics service call on the marker's EXPLICIT
  tap_action=toggle; icon state/tint mirrors the targets. `primaryEntity`
  picks in tiers so domain priority beats registry `hidden` (grouped lamps).
- **Island rooms** (v1.34): full nesting is legal (`polyContainsPoly`);
  parents render as evenodd paths with holes (`islandsOf`).
- **Kiosk mode** (v1.41): a card-config flag, not a mode — `_setMode` is
  hard-blocked, header hidden, swipe/carousel handled in the stage pointer
  pipeline (`swipeTarget`), per-screen multipliers in `LS_KIOSK`.
- **Nav persistence** (v1.38.2): `LS_NAV` stores {space, mode}; hash
  deep-link > saved > default_floor; stale-cache retry after the live load.


## Settings tiers (owner's principle, 2026-07-26)

Four levels: **global (config.settings) → space (space.settings) → room
(room.settings) → device (marker.*)**. Duplicated options are deliberate: the
more specific tier overrides the more general one; "unset" always means
"inherit". Resolution lives in pure helpers (`spaceDisplayOf`,
`roomFillModeOf`, `sourceValue`, `resolveTapAction`) — never inline in render.
The UI will later be unified around this model; until then each tier keeps its
own dialog (general settings gear / space gear / room-card gear / marker
dialog).


## Audit follow-ups (2026-07-27)

- **Content is authenticated.** `/houseplan_files/…` now serves ONLY the card
  bundle (a Lovelace resource must be public). Plans and marker files go
  through `HouseplanContentView` (`/api/houseplan/content/<plans|files>/…`,
  `requires_auth`). `contentUrl()` rewrites legacy stored URLs on read, so no
  storage migration is needed. Static paths cannot be unregistered — the old
  routes survive until the next HA restart.
- **Optimistic UI, stated explicitly (audit L7).** `_serverCfg` is mutated in
  place before a fallible save in ~22 places and there is no rollback: after a
  rejected save the UI shows the edit until the next reload. This is a
  deliberate optimistic-UI choice, not drift. Paths where it is unacceptable
  need their own rollback.
- **Split invariant.** `splitRoomPath` guarantees a partition: the two parts'
  areas sum to the original (within epsilon) or the cut is rejected.