v0.25.0

The language server now checks your templates the way lit-analyzer does, and
goes past it: lit-devtools check type-checks every binding with your own
TypeScript, and the editor runs the same check when you save. Unknown tags,
attributes, properties and slots, bindings Lit reads differently than
written, misplaced directives and mistakes in a component's declarations are
reported as you type, in Lit templates and for custom elements in JSX,
Astro, MDX and HTML, and fail an Oxlint run alike. Several of the new rules
are on by default, so an upgrade may show new warnings: each can be set in
diagnostics or silenced with a lit-ignore comment.

Editors & language server

• Added — lit-devtools check type-checks your bindings. Every
  .prop=${…}, attr=${…}, ?bool=${…} and @event=${…} expression is
  checked by your project's TypeScript, 5 or 7, against what the element
  takes, so .size=${this.name} fails CI when size is 'small' | 'large'
  and name any string; the values live(…) and ifDefined(…) pass on are
  checked too.
• Added — Binding type errors show in the editor when you save. The
  check lit-devtools check makes runs in the background for the saved file,
  so .size=${this.name} is underlined without waiting for CI. Set
  checkOnSave: false to turn it off.
• Added — lit-devtools check fits your project as it is. Run at a
  monorepo's root it checks every package with its own settings; a Vite
  project's tsconfig.app.json is found behind a tsconfig.json that only
  lists references; the binding-type severity decides whether problems
  fail the run, and elements missing from HTMLElementTagNameMap are listed
  instead of passing unchecked.
• Added — Unknown elements, attributes and properties are warnings. A
  tag, attribute or .property nothing defines is reported with the name you
  probably meant, and so is a component's attribute written with a value
  outside its type, size="huge", in Lit templates and for custom elements
  in JSX, Astro, MDX and HTML. ignoreTags and ignoreAttributes now
  silence them.
• Added — A slot the parent component doesn't have is a warning.
  <h2 slot="heder"> in a card with a header slot is reported, with the
  slot you probably meant or the ones it has.
• Added — Literal values that can't fit a binding are errors. A string
  in ?hidden=${'no'}, true in title=${true}, a number in @click=${1},
  or a value outside a property's union, .size=${'huge'}, is reported as
  you type under the new binding-type rule.
• Added — Templates Lit reads differently than written are reported. A
  component closed with /> or never closed, a ., ? or @ binding
  without ${…}, a stray quote next to an expression, and Polymer's
  name$= are flagged as you type.
• Added — A Lit directive where Lit can't apply it is an error.
  classMap outside class, styleMap outside style, ifDefined on a
  property, live on a listener, ref in an attribute, and repeat or
  unsafeHTML anywhere but between tags are reported before they throw.
• Added — Component declarations are checked. A tag
  customElements.define would refuse, an attribute: name HTML lowercases
  away, and a property whose type option doesn't fit its type, or a number
  or boolean without one, are reported in the component's file.
  property-visibility, off by default, flags @property() on private
  fields and @state() on public ones.
• Added — A field that replaces an element's own method is an error.
  @state() after or @property() remove replaces after() or remove()
  on the element, and a field named update or renderRoot breaks Lit's
  updates; shadowed-member reports them, in JavaScript too.
• Added — A component missing from HTMLElementTagNameMap is a
  warning, with a fix. Without the entry TypeScript can't tell what
  document.createElement('x-button') returns, and lit-devtools check can't
  check the element's bindings. The quick fix, or oxlint --fix, writes the
  declare global block.
• Added — missing-import reports components a file never imports.
  Turn it on to catch a tag used where nothing imports its definition, with a
  quick fix that adds the import; entries names an app entry whose imports
  count for every file.
• Added — Silence a problem with a lit-ignore comment.
  <!-- lit-ignore --> before an element in a template,
  // lit-ignore-next-line above a line, or // lit-ignore-file for the
  file, each optionally naming the rules, in the editor, in Oxlint and in
  lit-devtools check.
• Added — The manifests setting is read. List a manifest, a path or
  a URL, for components whose package ships none, and the editor completes,
  documents and checks them like any other.
• Fixed — Completion and hover see what you just typed in another
  file. A component added to one buffer was sometimes missing from
  completion in the next for a moment.
• Fixed — No false CSS problems around expressions in a css
  template. A selector or a whole block body written as ${…} made the
  rules around it report errors.
• Fixed — Code in an indented MDX fence stays code. A fenced block
  under a list item was read as markup.