First CRUD increment. Click "+ Add entity" on the Dashboard
toolbar → modal opens → form with entity_id / state / attributes
fields → Create validates client-side then POSTs /api/states/<id>
→ modal closes, toast confirms, dashboard refreshes.
New components:
frontend/src/components/Modal.ts (~110 LOC) — reusable accessible
overlay. open property; closes on Escape and backdrop click.
Heading prop; default + footer slots.
frontend/src/components/EntityForm.ts (~130 LOC) — three-field form
with public requestSubmit()/requestCancel() methods. Client-side
validation:
- entity_id matches /^[a-z][a-z0-9_]*\.[a-z][a-z0-9_]*$/
- state non-empty
- attributes parses as a JSON object (rejects array/scalar)
Emits hc-entity-submit / hc-entity-cancel events for host to
handle. Footer buttons live in the host (modal slot=footer).
frontend/src/pages/Dashboard.ts (+60 LOC) — toolbar with
"+ Add entity" button, modal state, POST handler that wraps
fetch with bearer token, success toast (3 s), refresh().
Browser-verified end-to-end (real homecore-server :8123):
- Toolbar button visible: Y
- Modal opens: Y
- 3/3 validation paths fire correctly:
BadID → "entity_id must match domain.snake_case"
blank state → "state must not be empty"
[1,2,3] attrs → "attributes must be a JSON object"
- Successful create: light.test_bulb POSTed; modal closes; toast
"Created light.test_bulb = on"; grid count went 10 → 11
- Persistence: hard reload, count stays
- 0 console errors (Lit dev-mode notices excluded)
Note: TypeScript caught a name collision — `attributes` is reserved
on HTMLElement (NamedNodeMap). Renamed the Lit @property to
`entityAttrs` so the class extends LitElement cleanly.
Co-Authored-By: claude-flow <ruv@ruv.net>
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