# House Plan architecture

One HACS repository (category **Integration**) ships the backend
(`custom_components/houseplan`), both Lovelace cards and the `/houseplan` panel
(`src/` → `dist/`). This document is the map: each subsystem gets a short
description and a link to its canonical document, which owns the details.

## Styles (#266)

`src/styles.ts` composes `cardStyles = [base, plan, devices, chrome, dialogs,
isoTiles]` from `src/styles/*.styles.ts`; the order is a cascade contract (the
golden set is accepted against it; `isoTiles` last so 2.5D tiles beat
equal-weight Flat marker rules, #649). `base` holds host, variables and rules
shared by two surfaces; `plan` stage ink, `devices` markers, `chrome`
toolbars/tabs/menus, `dialogs` dialogs/forms/pickers. `form-kit.styles.ts`
(#594), `editor-secondary.styles.ts` and the summary-panel sheets live outside
that aggregator. `test/styles-split.test.mjs` pins composition, no cross-file
duplicate selectors and `@media` wrappers; `scripts/dev/styles-diff.mjs` proves
a move refactor-only. Public selectors: `STYLING-HOOKS.md`.

## Layout

```
houseplan-card/
├─ src/                                  # card sources (TypeScript + Lit 3)
│  ├─ houseplan-card.ts                  # eager full card: View shell, HA lifecycle, lazy-runtime hosts
│  ├─ houseplan-panel.ts                 # /houseplan sidebar host around one full card (#486)
│  ├─ space-card.ts · space-render.ts    # read-only houseplan-space-card and its static renderer
│  ├─ houseplan-editor-runtime.ts        # lazy Plan/Devices/Background composition root
│  ├─ houseplan-onboarding-runtime.ts    # lazy first-space/import dialogs, independent of the editor
│  ├─ iso-*.ts · pdf/ · stairs*.ts · furniture*.ts  # 2.5D, PDF export, stairs, furniture (own docs)
│  ├─ devices.ts · rules.ts              # device list from registries; icon rules and exclusions
│  ├─ ha-binding-status.ts · device-presentation*.ts  # binding authority; marker face decisions
│  ├─ space-geometry.ts · wall-*.ts · physical-geometry.ts · logic.ts · types.ts  # pure, no Lit/DOM
│  ├─ config-store.ts · config-adoption.ts · command-stack.ts  # config cache, #500 boundary, Undo
│  ├─ sun.ts · day-cycle-render.ts       # window rays, four-phase background (SUN.md)
│  ├─ vacuum*.ts · radar-*.ts · zigbee-topology*.ts · summary-panel*.ts  # live subsystems
│  ├─ hp-dialog.ts · hp-confirm.ts · danger-confirm.ts · hp-help.ts · floating-surface*.ts
│  ├─ editor-runtime-loader.ts · version-recovery*.ts · editor-secondary.ts  # lazy loader; #462; tray
│  ├─ editor.ts · space-editor.ts        # Lovelace GUI config editors of both cards
│  └─ editors/ · render/ · styles/ · i18n/  # settings dialogs, SVG projections, sheets, locales
├─ dist/                                 # two stable entries, houseplan-assets.json, hashed chunks
├─ demo/                                 # demo rig and smokes; golden/ (HP-QA-01), performance/
├─ scripts/ · .github/workflows/         # build/bundle gates, release-*.mjs; CI and release
├─ custom_components/houseplan/          # the HA integration
│  ├─ __init__.py · store.py             # setup/unload; versioned stores and per-entry runtime data
│  ├─ websocket_api.py · http_api.py · auth.py  # WS commands, uploads, the one may_write policy
│  ├─ validation.py · coordinate_canonicalization.py  # pure schema validation, write canonicalisation
│  ├─ frontend_registration.py · frontend_assets.py · panel_registration.py  # resource, chunks, panel
│  ├─ import_export.py · decor_assets.py · plans.py  # backup/import, decor images, plan blobs
│  ├─ trails.py · vacuum_routes.py · radar*.py · virtual_lights.py  # live-subsystem backends
│  ├─ config_flow.py · const.py · system_health.py · diagnostics.py · repairs.py · support_*.py
│  └─ frontend/                          # release-only snapshot of dist (#657)
└─ docs/                                 # this documentation
```

Rollup emits two stable roots, `houseplan-card.js` and `houseplan-panel.js`,
plus hashed chunks and `dist/houseplan-assets.json` (graph, sizes, SHA-256).
The panel imports the card chunk by its hashed name, never through the card's
unversioned facade: entries are served without `Cache-Control`, and a stale
facade once ran an old card against the current backend (#535). Both roots keep
the fail-loud stale-load wrapper. View loads only the initial graph; editor,
onboarding, 2.5D (#649), PDF, locale and furniture-art graphs are lazy, each
passing the exact-build fingerprint handshake (one cache-busted retry, atomic
install), and `scripts/bundle-budget.mjs` fails a build whose lazy graph is
missing or leaks into the initial graph. The backend serves only manifest-listed
chunks. Commands and gates: `DEVELOPMENT.md` › Build, › Tests, › Release.

## Key decisions

1. **One repository — integration + panel + cards.** The integration serves
   its own JS; the exact versioned module URL is the resource identity, a
   writable Lovelace resource registry is authoritative and `add_extra_js_url`
   the truthful fallback. Each `houseplan/config/get` carries the authoritative
   `integration_version`: View offers a manual reload, kiosk reloads once per
   backend target in a safe idle state, the space card has no version controller
   (`DEVELOPMENT.md` › Resource registration and version recovery (#462)). After
   migrations succeed, setup registers the public `/houseplan` panel
   (`require_admin=False`, #486): a thin app-bar host around one ordinary full
   card, fail-soft, removed on unload only by the exact owner and setup
   generation (`UX-MODES.md` › Principle; `TESTING.md` › Installation / upgrade /
   removal). In a Sections `layout="grid"` slot HA owns the height: `.stage` is
   the shrinking flex child and transitions use the measured card height, never
   `window.innerHeight`; `getGridOptions()` is full width, 10 rows, min 6 (#648).
2. **Server-side storage, no token.** `store.py` keeps `.storage/houseplan.config`,
   `houseplan.layout` (marker positions) and `houseplan.virtual_lights`;
   `trails.py` keeps `houseplan.trails`. All traffic uses the frontend `hass`
   connection (Integration WS API below); House Plan opens no socket and holds no
   token. localStorage keeps a start-up snapshot and, only if no backend ever
   answered, a local layout. Registries come from one `ha-binding-status` fetch
   and subscription pair per HA connection, shared by every card on the page;
   live rows augment an older snapshot at once and a debounced full reload
   reconciles `disabled_by` even without registry events (`FILTERING.md` ›
   Behaviour).
3. **Reactivity.** Every `hass` update re-renders. Registry rebuilds also run the
   pure `device-area-relocation` resolver: pending ids override stale layout in
   full and static cards at once; the writer deletes those points before
   advancing Area provenance and restores them if the config write is rejected
   (a failed restore leaves the attention marker); only the moved device's
   Undo/Redo is invalidated; limited snapshots never infer movement
   (`CONFIG-COMPATIBILITY.md` › Marker Area provenance (#126)).
4. **One modal contract.** Card modals render through `hp-dialog`: `ha-dialog`
   if registered when the instance connects, otherwise a first-class native
   `<dialog>` for its lifetime (top layer, backdrop, reopened once if `:modal`
   was lost); a late registration never swaps an open surface, and alert
   confirmations stay native for real `alertdialog` semantics. The wrapper owns
   title, initial focus, Escape and a shadow-root-scoped restore-focus session
   (nested dialogs return to their trigger, a replacement to the first opener).
   `flex-content` forwards `flexcontent` so an inner scroller is height-bound
   (#508); the footer stays a full-width slot item; titles wrap; destructive
   actions stay left while Cancel/Save wrap right together. Dangerous actions
   use one eager `HpConfirmController` on `HouseplanCard` plus stateless
   `hp-confirm` (#32): replace-not-queue, every dismissal cancels, a token
   rejects stale decisions, callers re-resolve targets after `await`. Native
   `confirm()` is not a supported surface.
5. **Open passages are negative architecture (#157).** `type=passage` shares
   placement, wall cut and tunnels with other openings but has no leaf, binding
   or 2.5D panel; static wall fingerprints add only passage cuts, so door/window/
   gate output is unchanged (`CONFIG-COMPATIBILITY.md` › Open-passage opening
   type).
6. **One transient-surface contract (#68, #57).** `hp-dialog` keeps a scoped
   LIFO registry for help and colour-picker surfaces: Escape/toast close the top
   one first; a new one replaces the previous only inside the same dialog.
   `hp-help` and `hp-color-opacity` share `floating-surface.ts` placement and
   `floating-surface-controller.ts` (Popover top layer, dialog-owned portal
   fallback). Help is localized by the owning card and exists only when body and
   accessible label are both non-empty. Page-wide lazy runtimes — locales
   (#62, #400) and furniture artwork (#474, #593) — settle after two failed
   attempts into English / no artwork with one toast, never an inert card.
7. **One four-phase environment resolver.** `resolveDayCycle()` (`src/sun.ts`)
   and `src/day-cycle-render.ts` serve View, kiosk and the space card; plan
   content is never phase-filtered (`SUN.md` › Current four-phase background).
   The stage-sized outline root owns the triple drop-shadow and
   `will-change: filter`; its child is only the exact paper alpha silhouette,
   and the plan root gets an explicit stage-sized transform layer so Chromium
   never rediscovers it as an implicit overlap layer (#532, #582).

## Coordinate system

Plan geometry and marker positions are stored normalised on an unbounded canvas:
`0..1` = `NORM_W` (1000) render units, `±5000` validation, `1/240` lattice
(`src/canvas-constants.ts`). Source of truth: `CANVAS.md` › Principle, › Model,
› Grid precision and visual units, › Persisted coordinate canonicalisation.

## Card data model (runtime)

**Optional space model (#113).** Without authoritative spaces there is no
`SpaceModel`: `_spaceModel()` returns `undefined` and never invents one. Its
active-or-first choice serves rendering and navigation only; commands carrying a
stable space id use the exact `_spaceModelById()` and abort on a stale id before
any config, layout, file or service effect (`space-model-selection.ts`). The
first update that sees an authoritative empty `spaces` runs one cleanup (pointer
capture, gestures, draft/history, space dialogs, pending config write, back to
View); recreating a space re-arms it. Pure helpers may return empty results;
mutation entry points guard explicitly.

**`DevItem`** (`src/types.ts`) is rebuilt by `buildDevices()` (`src/devices.ts`)
from the active registry projection plus config markers: id, name, model, area,
space, icon, `entities[]` (active runtime entities only), `allEntities[]`
(metadata only), `primary` (first resolved state entity for single-target
actions; marker faces use the resolved role, `DEVICE-PRESENTATION.md`),
temp/hum, marker metadata and effective `controls`. `bindingStatus` (`active`,
`ha_disabled`, `orphaned`, `unverified`) comes only from
`resolveHaBindingStatus()`, never mutates markers, and gates every plan-level
consumer (Glow, climate, LQI, live text, openings, controls, vacuum).
Auto-discovery takes non-service devices whose HA Area is bound to a space. The
base icon is the first matching icon rule (`"<name> <model>"`) → entity
`device_class` → `mdi:chip`; a device with a `lock.*` entity is always
`mdi:lock`. Duplicate `name|area` pairs are numbered; HA light groups and Z2M
group devices become `lg_<entity>` items that fold their lamps. Hiding is
`FILTERING.md`.

## Live data

State, values, LQI and activity are resolved once per frame into one
`ResolvedDevicePresentation` (see Device markers); explicit `marker.value_source`
and `marker.value_badge` go through `src/device-value-badge.ts`. Decision table,
plate colours and LQI scale: [`DEVICE-PRESENTATION.md`](DEVICE-PRESENTATION.md).

### Presence radars (#485 Stage 1)

`marker.radar` is an optional versioned namespace saved only by the ordinary
config transaction. One backend `RadarCoordinator` per entry alone reads raw HA
states and streams clipped, ACL-filtered frames over `houseplan/radar/subscribe`;
observations, calibration samples and trails never reach config, uploads,
support reports or browser storage. Contract and code map: [`RADAR.md`](RADAR.md);
normative limits: [`specs/485-radar-presence-stage1.md`](specs/485-radar-presence-stage1.md).

### Robot vacuums

`src/vacuum-routes.ts` is the only map-to-space authority (six fail-closed
results, #162; mirrored byte-for-byte by `vacuum_routes.py`), `src/vacuum.ts`
owns telemetry normalization, path arbitration and smoothing, and `trails.py`
records runs server-side. Contract and code map: [`VACUUM.md`](VACUUM.md).

## Sizes

`icon_size` is a percentage of the plan (default 2.5; legacy px values > 8 fall
back to 2.5), converted once at the surface boundary and rendered in `cqw` inside
`.stage { container-type: inline-size }` — [`CANVAS.md`](CANVAS.md) §6.

## Sticky header

`.head` is `position: sticky; top: var(--header-height, 56px)`, so ordinary
dashboard cards keep `ha-card { overflow: visible }` (hidden overflow breaks
sticky). The bounded `panel-host` and Sections `layout="grid"` branches own their
complete height chain and clip at the external slot instead (Key decision 1).

## Device markers

`config.markers[]` records are
`{id, binding: 'device:<id>'|'entity:<eid>'|'virtual', space?, area?, hidden?, removed?, name?, icon?, …}`
plus presentation, light, control, vacuum and radar fields (`validation.py` is
authoritative). Registry devices appear on their own; a `device:` marker
overrides one, `entity:` covers groups/helpers, `virtual` is a manual icon. The
id (device id, `lg_<eid>` or `v_<rand>`) keys the layout. `hidden` is the
reversible hide flag, `removed` a never-rendered binding tombstone ([`FILTERING.md`](FILTERING.md)).

View, kiosk, the static card and the dialog preview share one pipeline:
`device-visual.ts` classifies, `device-presentation.ts` resolves sources, the pure
`device-presentation-policy.ts` owns priority, `device-pulse.ts` owns activity and
`device-face.ts` only paints. `normalizeDeviceDisplay()` is the mandatory read gate
for `display` (`badge|icon_ripple|value|static_icon|value_static_icon`; legacy
`ripple` → `icon_ripple`). The saved coordinate is the icon-core centre;
overlapping 44 px targets get one screen-space owner (`device-hit-owner.ts`),
latched for the whole pointer sequence. Rules: [`DEVICE-PRESENTATION.md`](DEVICE-PRESENTATION.md);
stored fields: [`CONFIG-COMPATIBILITY.md`](CONFIG-COMPATIBILITY.md).

Attachments are staged in `up_*`, promoted into `<config>/houseplan/files/<id>/`
on Save and served by signed `/api/houseplan/content/files/…` URLs (Integration
WS API). Custom Background images use the content-addressed
`<config>/houseplan/assets/` store (`asset_id` = SHA-256 of canonical bytes;
config never carries bytes or URLs) — [`DECOR-EDITOR.md`](DECOR-EDITOR.md) §7.

## Server-side configuration

`.storage/houseplan.config` holds `{model_version, spaces[], markers[], settings}`.
A space carries plan-image fields, `rooms[]` (with ordered `wall_ids`),
`wall_segments[]`, `partitions[]`, `wall_columns[]`, `openings[]`, `decor[]`,
`stairs[]` and `settings`. Coordinates keep the historical normalization
(`1.0` = `NORM_W` = 1000 render units) on an unbounded plane with a ±5000 guard
([`CANVAS.md`](CANVAS.md)); `plan_aspect` letterboxes the image and `plan_x/y`,
`plan_scale_x/y`, `plan_angle` transform it ([`DECOR-EDITOR.md`](DECOR-EDITOR.md) §3).
Layout v2 maps `device_id | rl_<roomId>` to `{s, x, y}`. Plan files are
copy-on-write `<config>/houseplan/plans/<space>.<token>.<ext>`, never deleted for
age ([`SCOPE.md`](SCOPE.md)). Migrations: [`CONFIG-COMPATIBILITY.md`](CONFIG-COMPATIBILITY.md).

### Persisted colour boundary

Every stored colour is exactly `#RRGGBB`: `src/color.ts` resolves it and
`validation.py::_COLOR` guards writes. Render-time resolvers re-apply a safe
default because old, imported or hand-edited stores are not migrated on read.
HA `rgb_color` is live state: three finite channels, clamped/rounded to 0–255 and
emitted only as generated `rgb(R, G, B)`. The final inline-style sink accepts
only those two forms; arbitrary CSS colour syntax would need a separate
product/security decision and must not be added to an individual sink.

## Room and independent wall geometry

Model v10 (#282, #306, #478): `wall_segments[]` is the authoritative catalog of
atomic room-wall intervals with stable ids, `rooms[].wall_ids[]` orders each
contour, and room polygons plus `walls[]` are read-compatibility projections.
Every accepted Walls-chain edge is an ordinary `partition`; `wall_columns` are
square/circular columns; neither creates or implicitly splits a room or HA area.
`cm:0` keeps a structural axis and identity without masonry; `space.zero_wall_style`
makes it dashed (transmits light) or solid (a zero-area barrier). Reads are
projection-only: a physical-geometry mutation builds a local candidate,
canonicalizes it, materialises the catalog (`src/wall-segment-model.ts` ↔
`wall_segment_model.py`, shared parity fixture), validates references and commits
one config transaction; ambiguity fails closed with no partial config, history or
revision. Model and lineage: [`WALL-THICKNESS.md`](WALL-THICKNESS.md) §1;
migrations and stale-client guard: [`CONFIG-COMPATIBILITY.md`](CONFIG-COMPATIBILITY.md)
(model v8–v10); rationale: [`adr/282-wall-geometry-representation.md`](adr/282-wall-geometry-representation.md).

Rooms may not partially overlap (lying on a shared wall is legal, a fully nested
island is supported). Merge/Split use **polyclip-ts** (not `polygon-clipping`,
see [`DEVELOPMENT.md`](DEVELOPMENT.md)): Merge accepts a pair only when the union
is one hole-free outline; Split cuts wall-to-wall and the larger part keeps the
room identity (name, area, devices).

`wallBodiesGeometry()` is the single physical masonry for flat full/static
rendering, 2.5D, paper, clean floor and Glow/sun occlusion. Its exterior shell
comes from the union of room centrelines plus surviving `outer` atoms; junctions
follow the bounded mitre/bevel rules (#249, #271, #272, #275, #288, #302, #309,
#310); independent bodies join through `physicalBodySet()` while raw quads keep
editor identity. The result is a typed component set (`ok`, `degraded-extra`,
`failed-core`; #197, #278): rendering keeps every valid component, mutation
preflight rejects `degraded-extra`, `failed-core` fails dark. It is computed state
only — cached per structural geometry, never written back, never rebuilt by HA
state ticks. Contract: [`WALL-THICKNESS.md`](WALL-THICKNESS.md) §2–§4, §9–§11.

## Markup editor

Card state: `_mode`, `_tool` (`select|draw|column|merge|split|resize|opening|
stairs|wallthick|delroom`), session `_path` on the `GRID_N = 240` lattice
(`_snap`, `CANVAS.md` §9). Committed geometry enters the named 50-command
Undo/Redo stack shared with Background (`DECOR-EDITOR.md` §6, §9); it survives
the echo of its own writes and clears on a newer external revision. Every
physical-geometry writer crosses one fail-closed boundary (#278,
`checkSpacePhysicalGeometry()`) before history/save, rechecked at the deferred
write; presentation edits bypass it. Contracts: Walls chain, faces, room
deletion, partitions — `WALL-THICKNESS.md` §6, §9–11, `CONFIG-COMPATIBILITY.md`
(#478, #461), `TOUCH-SUPPORT.md`; Resize (#277, #300) — `RESIZE.md`; near-axis
(#290, `src/near-axis.ts`) — `CANVAS.md` §9.3. `reconcileCoincidentPartitions`
(#276/#296/#477) and `normalizeWallIntervals` (#299) run plan-wide only in
explicit Optimize, locally in chain finish/room deletion, never in render or
ordinary saves. Saves strip the legacy root `space.segments`.

### Stairs (#663)

Separate Plan entity, not decor (`STAIRS.md`). Eager `StairViewRuntime`:
symbols, tooltip, guarded navigation; lazy `StairEditorRuntime`: drawing,
transforms, magnets, properties (a plan never loads the editor graph). The root
card keeps lifecycle, shared history/persistence and stage pointer terminals;
pure model, tread/trapezoid geometry and style resolution stay in `stairs.ts`.

The optional `color`/`opacity` and `fill_color`/`fill_opacity` fields are a
snapshot owned by the stair. Missing legacy fields resolve at render/dialog
time from the current decor default but are not written until the user saves
that stair. Screen renderers consume the colour fields; PDF deliberately uses
the same geometry with its existing monochrome ink palette.

## Editor chrome and contextual controls

One stable `.editbar` per editor: `.editbar-tools` (persistent tools,
Undo/Redo) and pinned `.editbar-end` (Close); transient controls never enter
this measured row. Selection actions, tool parameters, hints, palettes and the
approved groups (Opening, Stairs) come from one `EditorSecondaryModel` in the
single light-DOM `.editor-secondary-host` inside `.stage`
(`editor-secondary.ts`): outside the `_hdrH` measurement, pointer events only
on its visible surface, empty in the Device editor (future marker quick
actions go there). Mutating actions revalidate a deterministic `contextId`;
`Delete`/`Backspace` never fall through from it. Product rule: `UX-MODES.md`.

## Doors, windows, gates & passages

`space.openings[]` is plan geometry, not markers: `{id, type:
door|window|gate|passage, x, y, angle, length, host?, contact?, lock?, invert?,
flip_h?, flip_v?}`. `host` `{kind: wall|partition, id, t}` is authoritative and
`x/y/angle` its atomically refreshed projection; an absent host is the legacy
room-wall association, and no host ever falls back to a nearest wall
(`CONFIG-COMPATIBILITY.md` › #132/#157). One `OpeningWallIndex` feeds symbol,
cut, tunnel fill, Glow and the 2.5D face (`WALL-THICKNESS.md` §3–4,
`ISOMETRIC.md`, `LIGHT.md`). The Flat symbol follows easy-floorplan (MIT).
`openingAmount()` maps contact state to 0..1 — no sensor: door/gate open,
window closed; `unknown`/`unavailable` keep that default. Contact and lock are
opening-owned exact references: candidates follow HA binding status, render
reads the frozen active-registry projection (never raw `hass`), neither
consults marker tombstones. The `.oplock` badge never toggles a lock
(`resolveToggleIntent` → no-op, `SCOPE.md`); openings are edited only in Plan.

## Integration WS API

`auth.may_write()` is the single writer policy for WS and HTTP: administrators
always write; `admin_only` (default `true` when unset) restricts writing to
them; with `admin_only: false` other users write unless they belong to
`system-read-only`. A missing entry or incomplete group data fails closed.
Reads are deliberately broader: every authenticated user receives the complete
config/layout (no per-entity projection), trails without `source` entity ids
(#626) and may toggle virtual lights. **W** = writer-only (else
`unauthorized`); runtime-backed commands answer `not_ready` before setup.

| `houseplan/…` | Parameters | Result · domain errors |
|---|---|---|
| `config/get` | `space_id?`, `fields?`, `marker_fields?` (#256; project only the document) | `{config, rev, virtual_lights:{rev,config_rev,off[]}, can_write, can_optimize_undo, undo_kind, integration_version, support_api, decor_assets_api, summary_panel_api, radar_stage1_api?}` |
| `config/set` **W** | `config`, `expected_rev` | `{ok, rev}` · `conflict`, `too_large` (2 MiB), `invalid_format`, `missing_plan`, semantic codes below |
| `layout/get` | `space_id?` | `{layout:{id:{x,y,s?}}, rev, can_optimize_undo, undo_kind}` |
| `layout/set` **W** | `layout`, `expected_rev` | `{ok, rev}` · `conflict` (external clients; the card writes points) |
| `layout/update` **W** | `device_id`, `pos` | `{ok, rev, ignored?: removed\|missing_virtual}` — a tombstoned owner's late drag is acknowledged, not stored |
| `layout/delete` **W** | `device_id` | `{ok, rev}` (`rev: null` when nothing was stored) |
| `space/delete` **W** | `space_id`, `expected_config_rev`, `expected_layout_rev` | `{ok, config_rev, layout_rev, removed_layout}` · `space_in_use`, `space_not_found`, `invalid_space_id` |
| `plan/optimize` **W** | `config`, `layout`, both expected revs | `{ok, config_rev, layout_rev, can_undo}` — also the server-side wall-model migration barrier |
| `plan/optimize_undo` **W** | both expected revs | restores the one-deep Optimize/full-import backup · `no_backup` after any later edit |
| `geometry/repair` **W** | `space_id`, `aspect`, `dry_run?`, `undo?`, `expected_rev?` | manual re-transform of one space's positions (HP-1500-01) with one-deep `repair_backup` · `nothing_to_repair`, `no_backup` |
| `export/create` **W** | `kind: full\|space`, `space_id?`, `plan_only?`, `card_version` | `{document, filename}` |
| `import/revalidate` **W** | `token`, `duplicate_policy?` | refreshed preview and current revisions |
| `import/apply` **W** | `token`, both expected revs, `duplicate_policy?`, `confirm_missing_content?` | paired commit; full import gets one-deep undo · `conflict`, `preview_expired`, `content_confirmation_required`, `missing_plan`, `missing_content` |
| `virtual_light/toggle` | `marker_id` | `{marker_id, on, rev}` · `not_toggleable` |
| `trail/get` / `trail/delete` **W** | — / `marker_id` | `{trails:{marker:{current,previous}}}` / `{ok, removed}` |
| `plans/list` **W** / `plans/delete` **W** | — / `name` | newest 60 `{name,url,size,modified,used_by}` + `total` / `{ok, removed}` · `in_use`, `invalid_name` |
| `plan/set` **W** | `space_id`, `ext`, `data` (base64) | `{ok, url}` — kept only for pre-#617 cards; current cards use HTTP |
| `files/migrate` **W** | `from_id`, `to_id` | `{ok, mapping, copied}` — copies, never moves or overwrites |
| `files/cleanup` **W** | `marker_id` | `{ok, removed, kept}` — removes only files the stored config does not reference |
| `assets/list` **W** / `assets/delete` **W** | — / `asset_id` | catalog with authoritative `used_by` / `{ok, removed}` · `in_use` |
| `assets/resolve` | `asset_ids[]` (≤200) | `{assets, missing}`; non-writers resolve only ids the saved config uses |
| `content/sign` | `paths[]` | `{urls}` — 24 h `authSig`, only `/api/houseplan/content/…`, first 200 paths |
| `support/*` **W**, `radar/*` | — | `SUPPORT-PRIVACY.md`, `RADAR.md` |

Semantic write codes: `invalid_config`, `invalid_passage_fields`,
`invalid_partition_opening_host`, `invalid_partition_opening_jamb_margin`,
`wall_model_client_outdated`, `wall_model_migration_blocked` (Optimize),
`junction_limit_<rule>`, `invalid_radar`, `invalid_light_entity`,
`invalid_vacuum_map_route`, `*marker_control*`, `invalid_value_badge*`; paired
writers add `commit_failed`. Events: `houseplan_config_updated`,
`houseplan_layout_updated` (`{rev}`), `houseplan_virtual_light_updated`,
`houseplan_trail_updated`.

HTTP views (`requires_auth`, same policy): `POST /api/houseplan/upload`
(marker attachment), `/plans/upload` (#617), `/assets/upload`
(`DECOR-EDITOR.md` §7), `/import/preview` and `GET
/api/houseplan/content/{kind}/{sub}/{name}` (`nosniff`; SVG only gets a
`sandbox` CSP, HP-1454-01). Only the manifest-gated bundle under
`/houseplan_files/` is public; legacy `/houseplan_files/plans|files` URLs are
still recognised in stored config but no longer served
(`CONFIG-COMPATIBILITY.md` › Legacy content URLs).

**Invariants**

- *Optimistic locking.* Each config/layout writer takes `write_lock`, resolves
  a pending pair, then checks revisions before validation, no-op detection or
  file collection. `expected_rev` may be omitted only at `rev = 0` (#340,
  #356). External writers read `rev` via `config/get`/`layout/get`, send it as
  `expected_rev`, and on `conflict` re-read and retry (#368). A canonical no-op
  keeps revision, events and the maintenance backup.
- *Paired writes* (Optimize, Optimize Undo, full import, space delete) use the
  durable `optimize_pending` intent and one-deep `optimize_backup`
  (`kind: optimize|import`) — `CONFIG-COMPATIBILITY.md` › #491. Events fire only
  after both halves are durable; Store exceptions are resolved by reloading
  and comparing exact payloads; layout-store writes go through
  `async_save_layout_state` so unknown metadata survives.
- *Validation is the server's.* Schema/semantic checks run in the executor
  under the lock; the browser never parses an import. Frontend preflight
  (`src/plan-geometry-preflight.ts`) only avoids doomed calls.
- *Files* (`SCOPE.md` › Standing rule): uploads claim a fresh name
  (`reserve_filename`, `O_EXCL`), plans are copy-on-write
  `<space>.<token>.<ext>` (a space id cannot contain `.`), and `check_quota`
  bounds bytes/files/free disk at upload. `config/set` collects, under its
  lock, only what its own commit replaced; a daily pass runs the collectors
  with the stored config on both sides and sweeps `.upload-` temporaries. A
  newly referenced internal plan must exist (`missing_plan`; import also checks
  attachments). A usable `Content-Length` is checked before streaming, the
  staged size again under `upload_lock`, which also serialises image decoding.
  Collection classifies by **owner**, not by "is it referenced" (HP-1465-01);
  nothing is deleted for being old except `up_*` staging after
  `PLAN_ORPHAN_TTL_S` (1 h), and `plans/list`/`plans/delete` make "we never
  delete" livable:

  | Case | 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 (the image was imported and may be nowhere else) | **kept** |
  | Space has a plan plus another file of its own (a rejected save) | **kept** — ageing these out raced the retry |
  | Marker in both, attachment dropped from its list | removed immediately |
  | Marker gone | **kept** |
  | Attachment in `up_*` (a dialog never saved) | removed after `PLAN_ORPHAN_TTL_S` |
  | Marker there, file it never listed (a rejected upload) | **kept** |
- *Import preview* streams ≤8 MiB, rejects duplicate/prototype keys,
  non-finite numbers and future model versions, and keeps the candidate in
  memory for 10 min behind a token bound to the user, candidate digest and
  both revisions (global and per-user caps). *Export* deep-copies one coherent
  pair under the lock and builds outside it.
- *Virtual-light state* lives in its own Store (`CONFIG-COMPATIBILITY.md`);
  toggles reply immediately and coalesce into one delayed durable write,
  flushed before config transitions and unload. A cached snapshot never
  authorizes an optimistic toggle.

**Client side**

- `_writeConfig()` keeps one `config/set` in flight, each carrying the previous
  reply's revision (HP-1454-03). A rejected physical transaction restores the
  earliest server-backed snapshot of every affected space and reloads (#314).
- `src/config-adoption.ts` (#500) owns config/layout body + revision +
  fingerprint. It changes only by authoritative adoption
  (`adoptAuthoritativeGated`, profiles `reload`/`post-write`), own-write
  acceptance (`acceptConfigWrite`, `acceptPairWrite`) or warm-cache restore;
  paired writers take revisions from the re-read. Local staging is limited to
  files pinned by `test/config-adoption-ownership.test.mjs`. Ordinary debounced
  editor saves remain optimistic: a rejection that is neither a revision
  conflict (which reloads) nor a physical-geometry rollback keeps the local edit
  with a failure toast until the next authoritative reload. Writers that must
  undo on rejection capture an `OptimisticAttempt`
  (`beginOptimistic`/`rollbackOptimistic`), which restores the server-backed
  body only while that failed candidate is still current (#442, #500).
- `src/config-reload-authority.ts` (#543): each reload holds a generation-scoped
  claim; a superseded one ends with no side effect.
- `ContentSigner` (`src/signing.ts`) is the only signer for both cards:
  `MAX_SIGN_PATHS` (200) is shared with `const.py`; the cache is age-aware and
  pruned to live URLs; queued/in-flight are distinct, failures back off and
  in-flight entries expire after `SIGN_INFLIGHT_MS`.
- Room climate is one `roomClimateMap()` pass per hass snapshot (#317) shared
  by full and static cards; exact `entity:` placement beats its parent
  `device:` (no double vote); never call the `areaClimate()` wrapper in render.
- Load, continuity and fixed-floor rules: `WARM-REMOUNT.md` § 5.

## Second card: houseplan-space-card (read-only)

One bundle registers `houseplan-card` (interactive) and the read-only
`houseplan-space-card` (one space; `src/houseplan-card.ts` imports
`./space-card`). User options, `fit` and the deep link: `USER-GUIDE.md` §18,
`CANVAS.md` §4.4, `LIGHT.md` › Which surfaces render pools. Shared modules keep
the two views from diverging: `space-geometry.ts` (pure model/position math),
`space-render.ts` (`renderSpaceStatic()`: plan, rooms and markers through
`buildDevices`, `ResolvedDevicePresentation` and `renderDeviceFace`, no marker
handlers), `glow-scene.ts` (opt-in `light_pools`, per-card bounded caches) and
`config-store.ts` — one module-level `{config, rev, configFingerprint, layout,
layoutRev, layoutFingerprint}` cache and one subscription for all embedded
cards, seeded from `houseplan_card_cfg_v1` and refreshed on
`houseplan_config_updated`/`houseplan_layout_updated` without first clearing
the visible snapshot. `.hp-static-stage` and every descendant
(`*, *::before, *::after`) are `pointer-events:none`, overriding the markers'
44 px opt-in (#564, #664); only the footer button is interactive, asserted by
`demo/smoke_space_card.mjs` with `elementFromPoint`. A card with `floor`
ignores `#space=`.

## Subsystems with their own canonical documents

- **Decor, plan image, furniture, custom images** — `space.decor[]` is a purely
  visual layer with one selection/transform/history pipeline; image bytes live
  only in the asset store: [DECOR-EDITOR](DECOR-EDITOR.md), [FURNITURE](FURNITURE.md).
- **Light and Glow** — one visibility region per source (#71); Glow is an overlay
  independent of the data fill (#55): [LIGHT](LIGHT.md). **Room fill** —
  `resolveEffectiveRoomFill()` is the single projection for room floors,
  clean-floor holes and opening tunnels; `room_color` styles only borders and
  names; custom colour and legacy tokens (#56, #581):
  [CONFIG-COMPATIBILITY](CONFIG-COMPATIBILITY.md).
- **Device state, light membership, action** — `resolvedDeviceStateEntities`,
  `resolvedLightSources` and `src/device-toggle.ts` are the only resolvers
  (#94, #251, #318, #381): [DEVICE-PRESENTATION](DEVICE-PRESENTATION.md).
- **Zero-thickness walls, nested rooms** — `resolveZeroWalls()` feeds every
  renderer, Glow and sun (#306): [WALL-THICKNESS](WALL-THICKNESS.md). **Kiosk,
  navigation** — kiosk is a card flag, not a mode; `LS_NAV` stores only the space
  (#93, #210): [UX-MODES](UX-MODES.md).

## Camera and mode transitions (#101, #82)

Two one-token/one-RAF controllers own every animated camera change and leave
no CSS timers or WAAPI animations behind. `ModeTransitionController`
(`src/mode-transition.ts`) is the only timeline for entering, leaving and
switching editors: it interpolates measured chrome height, stage geometry,
world-space camera centre, logarithmic pixels-per-unit, stage/paper colours,
day/night brightness and presentation weights together, deriving each `viewBox`
from the current stage aspect; the stage is inert meanwhile, header tabs stay
live for a retarget. `src/viewport-transition.ts` animates discrete zoom in a
settled mode with the same easing but only `{zoom, viewBox}` (no chrome,
background, layer opacity or CSS transform) and lives in the core View bundle.
The component stays the sole camera writer; ownership boundaries and timings:
[CANVAS](CANVAS.md) › View/editor camera handoff and §5.

## 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 wins and "unset" always means "inherit". Resolution
lives in pure helpers (`spaceDisplayOf`, `roomFillModeOf`, `roomGlowOf`,
`roomTempRangeOf`, `sourceValue`, `resolveToggleIntent`), never inline in render;
each tier keeps its own dialog (General settings, space, room, marker).

## Schema as the source of truth (#33)

The Voluptuous schema in `custom_components/houseplan/validation.py` is the
single owner of the persisted config/layout shape. The generated manifest
`scripts/config-schema.json`, the enum parity test with its self-checking
allow-list, the decision registry `scripts/config-field-registry.mjs` and the
lifecycle fixtures keep every other world honest against it:
[CONFIG-COMPATIBILITY](CONFIG-COMPATIBILITY.md) › Schema manifest and parity.

## No hidden discovery knobs (#44)

Every stored key that shapes device discovery is a visible, supported setting
or does not exist. `settings.group_lights` and `settings.exclude_integrations`
live in the device catalog's Discovery-filters section and are resolved only by
`effectiveExcludedIntegrations()`: [FILTERING](FILTERING.md) › Seeding.

## Contextual Zigbee topology (#54, #457, #464)

The initial View graph holds only the fail-closed settings reader and a dynamic
overlay bridge; the overlay chunk loads only for a saved
`settings.zigbee_topology.enabled === true`, a real HA admin, full-card View and
a non-kiosk surface. General Settings loads provider transport only when an
enabled setting needs status or the admin presses a provider action.
`zigbee-topology.ts` normalises ZHA and Zigbee2MQTT into unordered edge pairs
with directional observations, maps IEEE nodes through exact registry ownership
and resolves only edges incident to the hovered marker, never inventing
neighbours. `zigbee-topology-runtime.ts` keeps a per-connection memory cache with
in-flight dedupe: ZHA reads `zha/devices` without a scan; Z2M checks the retained
bridge-info topic, sends one correlated raw `routes:false` request through
`mqtt.publish`, rejects retained/foreign/late replies and always unsubscribes.
The pointer-transparent overlay is a child of the `.devlayer` camera, projected
once with the markers by `live-viewport.ts`; only the source and drawable
neighbour markers are promoted above it, through transient attributes the
overlay owns and clears. Unknown-LQI links are a 4 px `#2e2e2e` casing under the
2 px grey core. Persistence, privacy: [CONFIG-COMPATIBILITY](CONFIG-COMPATIBILITY.md).

## Live viewport: a transform per frame, a `viewBox` on a budget (#531, #579)

Rewriting the SVG `viewBox` re-rasterises the whole scene, so per-frame writes
made panning crawl. `paintLiveViewport` keeps an anchor (the `viewBox` in the DOM
and when it was written) and moves scene nodes each frame with the HTML layers'
projective transform (`liveLayerProjection`, `transform-origin: 0 0`);
`needsViewBoxRefresh` rewrites the anchor only after `LIVE_VIEWBOX_REFRESH_MS`
(100 ms) or a `LIVE_VIEWBOX_REFRESH_SHIFT` (15 %) shift/scale change — module
constants, not settings. Scene nodes project from the anchor, HTML layers from
the last settled Lit frame; both land on the current view, keeping #451's
one-CSS-pixel marker contract on every frame. `.stage` stays the outer clip, but
a transformed scene SVG gets inline `overflow: visible` so rasterised content
covers the incoming edge, even with the pointer held still (#544); HTML layers
never do. From the first live paint to the terminal commit a scene SVG stays in
one compositor lifecycle: a refresh or Lit frame may replace its anchor but never
demote/re-promote it — HA Companion WebView shows that as a blank frame (#579).
The day-cycle paper outline joins these roots before the first camera move; the
static card uses its stage-sized form from the first frame (#582, Key decision 7).
Unchanged values are never rewritten, so idle frames stay byte-identical;
`commitHouseplanViewport` removes the transforms and forces the final `viewBox`.
After the camera leaves its byte-compatible 100% view, the flat wall hatch uses
an analytic user-space repeating gradient rather than a repeated stroked bitmap
tile (#685). Therefore the terminal transform-free SVG is rasterised directly
for its final fractional scale; the live transformed frames may still be
temporarily soft, but the idle frame must not retain a resampled hatch texture.
Door, window and gate strokes share that terminal SVG, and passages remain real
negative wall geometry.

## English and Russian ship whole (#400)

`en` and `ru` are synchronous dictionaries in the initial chunk; `de` and `fr`
load lazily (`src/i18n/registry.ts`), editor-only strings included. At the
decision the 38 settings-help entries of #86 cost 2 654 B gzip (0.9 % of the
initial-View budget); splitting would need a second dictionary half, a runtime
merge, an extra request and a second source for the `en.json` key type (#391).
Budget planning assumes whole dictionaries; revisit only if editor text grows by
tens of kilobytes.

## Backend quality gates (#42)

`tests_backend/requirements.txt` is the single source of backend CI dependencies;
ruff, strict mypy, the `sys.modules` guard, the coverage baseline and the
`geometry_parity` job: [TESTING](TESTING.md) › Backend quality gates.
`const.ERROR_CODES` / `ERROR_CODE_FAMILIES` are THE stable error contract: every
emitted code is registered and localized (scanner test); `invalid_passage_fields`
and `invalid_partition_opening_jamb_margin` carry structured JSON details; the
frontend renders unknown codes localized, code first, raw messages to the console.

## Summary panel boundary (#437)

`settings.summary_panel` is the only shared persistence of this read-only overlay;
`prepare_ordinary_summary_candidate()` is the common backend boundary of
`config/set` and `plan/optimize` (full import bypasses it), and
`config/get.summary_panel_api`, never cached config, grants editing. Persistence
and local keys: [CONFIG-COMPATIBILITY](CONFIG-COMPATIBILITY.md) › Summary panel namespace.
`summary-panel.ts` owns defaults, stable ids, fit predicates and local-key
encoding; `summary-panel-picker.ts` a non-DOM `entity_id + friendly_name` index
reused across state changes; `summary-panel-runtime-loaded.ts` the lazy View
controller — a screen-space, non-SVG sibling of the camera layer outside content
bounds, with one minute-aligned timer and a lifecycle generation binding dialog,
draft, picker and async work to one route/user/permission/kiosk identity.
`summary-runtime-loader.ts` shares code, never state, and attaches a warm runtime
before the first render ([#506](specs/506-startup-performance.md)).
`summary-panel-editor.ts` loads on the settings button; its revision-checked
shared write precedes the local show choice. #505 styles and the 190 ms phases
stay lazy and never move the camera; editors and the space card never load the
panel. Device totals need an authoritative registry snapshot and dedupe parent
device ids before visual filters; clean area unions canonical room floors per
space with that space's `cell_cm`.

## Private support boundary (#43)

Help & feedback is rendered by the lazy editor runtime even in View; form state
is component memory only. Report controls appear only when
`config/get.support_api` equals `SUPPORT_API_VERSION` (1); release versions are
diagnostic. `houseplan/support/preview` (`may_write`, bounded capability enums,
dialog-scoped id) loads one coherent config/layout pair under the shared write
lock and passes disposable validated copies to `support_package.py`, a strict
projection boundary: a new allowlisted object with package-local pseudonyms and
canonical sorted JSON, never raw storage redacted afterwards. Bytes, SHA-256 and
expiry stay in `HouseplanData` memory, bound to user and draft for ten minutes;
preview, download and submit use those bytes; `preview/discard` (idempotent) or a
confirmed submit consumes the token. `houseplan/support/submit` re-validates text,
resolves only an owned live token and calls `support_transport.py`: one
compile-time HTTPS URL, no redirects, bounded timeouts and response size, stable
local failure codes that never reflect the response. The relay
(`scripts/support-relay/`) deploys separately and is excluded from the HACS
artifact. Content and retention: [SUPPORT-PRIVACY](SUPPORT-PRIVACY.md).

## Mutation tooling boundaries (#558)

`scripts/mutation-gate.mjs` stays the stable CLI but is only an orchestrator and
compatibility export surface over `mutation-registry.mjs` (declarations),
`mutation-selection.mjs` (diff/guard-input selection), `mutation-evidence.mjs`
(witness fingerprints, caught ledger) and `mutation-execution.mjs` (worktree
runs); dependencies never point back to the CLI. Guard-input caching is
invocation-scoped (one resolver, one tracked-file snapshot); persisted success
exists only in the explicit caught-witness ledger. Usage: [TESTING](TESTING.md).