[A11Y-12317] [A11Y-12318] Add SIA-R121 and SIA-R122.

[pooya-si]

Description

• Add a new rule to verify whether <ul>, <ol>, and <dl> only contain the child element types the HTML spec allows.
• Add R120 to identify whether a document includes elements with duplicate access keys.

Jira Ticket

A11Y-12317
A11Y-12318

[changeset-bot]

🦋 Changeset detected

Latest commit: e9f470a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 76 packages

Name	Type
@siteimprove/alfa-rules	Minor
@siteimprove/alfa-act	Minor
@siteimprove/alfa-affine	Minor
@siteimprove/alfa-applicative	Minor
@siteimprove/alfa-aria	Minor
@siteimprove/alfa-array	Minor
@siteimprove/alfa-bits	Minor
@siteimprove/alfa-branched	Minor
@siteimprove/alfa-cache	Minor
@siteimprove/alfa-callback	Minor
@siteimprove/alfa-cascade	Minor
@siteimprove/alfa-clone	Minor
@siteimprove/alfa-collection	Minor
@siteimprove/alfa-comparable	Minor
@siteimprove/alfa-continuation	Minor
@siteimprove/alfa-css-feature	Minor
@siteimprove/alfa-css	Minor
@siteimprove/alfa-device	Minor
@siteimprove/alfa-dom	Minor
@siteimprove/alfa-eaa	Minor
@siteimprove/alfa-earl	Minor
@siteimprove/alfa-either	Minor
@siteimprove/alfa-emitter	Minor
@siteimprove/alfa-encoding	Minor
@siteimprove/alfa-equatable	Minor
@siteimprove/alfa-flags	Minor
@siteimprove/alfa-fnv	Minor
@siteimprove/alfa-foldable	Minor
@siteimprove/alfa-functor	Minor
@siteimprove/alfa-generator	Minor
@siteimprove/alfa-graph	Minor
@siteimprove/alfa-hash	Minor
@siteimprove/alfa-http	Minor
@siteimprove/alfa-iana	Minor
@siteimprove/alfa-iterable	Minor
@siteimprove/alfa-json-ld	Minor
@siteimprove/alfa-json	Minor
@siteimprove/alfa-lazy	Minor
@siteimprove/alfa-list	Minor
@siteimprove/alfa-map	Minor
@siteimprove/alfa-mapper	Minor
@siteimprove/alfa-math	Minor
@siteimprove/alfa-monad	Minor
@siteimprove/alfa-network	Minor
@siteimprove/alfa-option	Minor
@siteimprove/alfa-painting-order	Minor
@siteimprove/alfa-parser	Minor
@siteimprove/alfa-performance	Minor
@siteimprove/alfa-predicate	Minor
@siteimprove/alfa-record	Minor
@siteimprove/alfa-rectangle	Minor
@siteimprove/alfa-reducer	Minor
@siteimprove/alfa-refinement	Minor
@siteimprove/alfa-result	Minor
@siteimprove/alfa-rng	Minor
@siteimprove/alfa-sarif	Minor
@siteimprove/alfa-selective	Minor
@siteimprove/alfa-selector	Minor
@siteimprove/alfa-sequence	Minor
@siteimprove/alfa-set	Minor
@siteimprove/alfa-slice	Minor
@siteimprove/alfa-string	Minor
@siteimprove/alfa-style	Minor
@siteimprove/alfa-table	Minor
@siteimprove/alfa-test	Minor
@siteimprove/alfa-thunk	Minor
@siteimprove/alfa-time	Minor
@siteimprove/alfa-toolchain	Minor
@siteimprove/alfa-trampoline	Minor
@siteimprove/alfa-tree	Minor
@siteimprove/alfa-trilean	Minor
@siteimprove/alfa-tuple	Minor
@siteimprove/alfa-url	Minor
@siteimprove/alfa-wcag	Minor
@siteimprove/alfa-web	Minor
@siteimprove/alfa-xpath	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[Copilot]

🟡 Changes recommended

Flattened-tree and namespace handling can produce incorrect results, and the required API report is outdated.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

Adds stable rule SIA-R119 to validate HTML list content models.

Changes:

• Implements validation for <ul>, <ol>, and <dl>.
• Adds comprehensive rule tests.
• Exports the rule and adds release metadata.

File summaries

File	Description
.changeset/brave-lists-gather.md	Documents the new rule.
packages/alfa-rules/src/rules.ts	Exports R119.
packages/alfa-rules/src/sia-r119/rule.ts	Implements list validation.
packages/alfa-rules/src/tsconfig.json	Includes the rule source.
packages/alfa-rules/test/sia-r119/rule.spec.tsx	Tests rule behavior.
packages/alfa-rules/test/tsconfig.json	Includes the new tests.

Review details

Suppressed comments (4)

packages/alfa-rules/src/sia-r119/rule.ts:85

• This also checks flattened-tree text rather than direct DOM text. For example, text in the light DOM of a shadow-host <div> wrapper can be hidden by its shadow root and escape the <dl> group validation. Use the default DOM-tree traversal, matching the content model being validated.

    .children(Node.fullTree)

packages/alfa-rules/src/sia-r119/rule.ts:91

• This accepts any element whose local name is li, including a foreign-namespace element created with createElementNS. The content model requires an HTML <li>, so include the HTML namespace in the predicate.

  const disallowed = elementChildren(target).reject(hasName("li"));

packages/alfa-rules/src/sia-r119/rule.ts:135

• A wrapper can similarly pass with foreign-namespace dt/dd children because hasName compares only the local name. Validate that the wrapper children are HTML elements before treating them as a well-formed group.

  if (!children.reject(hasName("dt", "dd")).isEmpty()) {

packages/alfa-rules/src/sia-r119/rule.ts:100

• The allowed direct children are matched only by local name, which lets foreign-namespace div, dt, or dd elements satisfy the HTML <dl> content model. Require Namespace.HTML in this predicate so those nodes are reported as disallowed.

  const disallowed = children.reject(hasName("div", "dt", "dd"));

• Files reviewed: 6/6 changed files
• Comments generated: 3
• Review effort level: Balanced

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[Copilot]

🟡 Changes recommended

The text check can produce incorrect results for elements with shadow content, and one diagnostic is inaccurate for description lists.

Get a fresh assessment by requesting another Copilot review.

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 2
• Review effort level: Balanced

[Copilot]

🟢 Approval recommended

The implementation matches the documented content models and has comprehensive focused coverage.

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[Copilot]

🔵 Needs a closer look

Flat-tree traversal produces incorrect HTML content-model results for slotted children.

Review details

Suppressed comments (1)

packages/alfa-rules/src/sia-r119/rule.ts:101

• Node.fullTree uses flat-tree traversal (packages/alfa-dom/src/node/node.ts:397-407), which replaces a direct <slot> with assigned light-DOM nodes (packages/alfa-dom/src/node/slotable/element.ts:174-186). HTML content models constrain actual DOM children, so <ul><slot></slot></ul> remains invalid even when <li> nodes are assigned; assigned text is likewise not direct list text. This currently makes the rule contradict its stated HTML-spec check and causes the slot tests to lock in incorrect results. Use default children() for both element and text checks, remove the straySlots workaround, and update the slot expectations accordingly.

    .children(Node.fullTree)

• Files reviewed: 6/6 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[pooya-si]

• Node.fullTree uses flat-tree traversal (packages/alfa-dom/src/node/node.ts:397-407), which replaces a direct <slot> with assigned light-DOM nodes (packages/alfa-dom/src/node/slotable/element.ts:174-186). HTML content models constrain actual DOM children, so <ul><slot></slot></ul> remains invalid even when <li> nodes are assigned; assigned text is likewise not direct list text. This currently makes the rule contradict its stated HTML-spec check and causes the slot tests to lock in incorrect results. Use default children() for both element and text checks, remove the straySlots workaround, and update the slot expectations accordingly.

@copilot The case you originally raised is already caught. <ul><slot></slot></ul> in an ordinary document now fails, naming the slot. straySlots is not a workaround for the traversal; it is what closed that gap. It targets precisely the slot that can never be assigned anything, because its root is a document rather than a shadow root.

[Copilot]

🔵 Needs a closer look

Flattened-tree traversal validates slotted content instead of the lists’ actual DOM children.

Review details

Suppressed comments (2)

packages/alfa-rules/src/sia-r119/rule.ts:101

• Node.fullTree requests flattened traversal (packages/alfa-dom/src/node/node.ts:403-407), and Element.children consequently replaces a direct <slot> with its assigned nodes (packages/alfa-dom/src/node/slotable/element.ts:174-189). This makes a shadow-tree <ul><slot></slot></ul> pass whenever <li> nodes are assigned, even though the list's actual child is the disallowed <slot>. Content-model validation should use children() and remove the shadow-dependent straySlots exception; the slot tests that currently expect this case to pass need to be updated as part of the fix.

    .children(Node.fullTree)

packages/alfa-rules/src/sia-r119/rule.ts:108

• The text check also uses the flattened tree, so assigned light-DOM text is reported as direct text of the list. For <ul><slot></slot></ul> with text assigned to the slot, the actual invalid child is <slot>, but this short-circuits with HasDisallowedText instead. Inspect default children() here so only actual direct text nodes participate in the content-model check, and update the corresponding test expectation.

    .children(Node.fullTree)

• Files reviewed: 6/6 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[pooya-si]

🔵 Needs a closer look

Flattened-tree traversal validates slotted content instead of the lists’ actual DOM children.

Review details

Suppressed comments (2)

packages/alfa-rules/src/sia-r119/rule.ts:101

• Node.fullTree requests flattened traversal (packages/alfa-dom/src/node/node.ts:403-407), and Element.children consequently replaces a direct <slot> with its assigned nodes (packages/alfa-dom/src/node/slotable/element.ts:174-189). This makes a shadow-tree <ul><slot></slot></ul> pass whenever <li> nodes are assigned, even though the list's actual child is the disallowed <slot>. Content-model validation should use children() and remove the shadow-dependent straySlots exception; the slot tests that currently expect this case to pass need to be updated as part of the fix.

    .children(Node.fullTree)

packages/alfa-rules/src/sia-r119/rule.ts:108

• The text check also uses the flattened tree, so assigned light-DOM text is reported as direct text of the list. For <ul><slot></slot></ul> with text assigned to the slot, the actual invalid child is <slot>, but this short-circuits with HasDisallowedText instead. Inspect default children() here so only actual direct text nodes participate in the content-model check, and update the corresponding test expectation.

    .children(Node.fullTree)

• Files reviewed: 6/6 changed files
• Comments generated: 0 new
• Review effort level: Balanced

@copilot review your suggestion against cons of using children() e.g. a list whose items are slotted in from the light DOM

[Copilot]

🔵 Needs a closer look

Flattened-tree traversal validates slotted content instead of the lists’ actual DOM children.

...

I withdraw the blanket recommendation to switch to children(). It would change what this rule checks:

• For a shadow-tree <ul><slot></slot></ul> receiving <li> elements, children() sees only the slot and reports a failure despite the assembled list having the intended structure.
• For assigned loose text or disallowed elements, it reports the slot instead of inspecting the problematic content. An empty shadow-tree slot would also fail rather than represent an empty list.
• The ordinary-document slot case is already covered by straySlots() and its tests; removing it while retaining flattened traversal would lose that coverage.

Default traversal is appropriate for a strict direct-DOM HTML conformance check. Flattened traversal serves the assembled-list accessibility check explicitly intended by the new slot tests. Those are different contracts; my earlier suggestion privileged the former without accounting for the latter.

Given the intended slot support, I recommend keeping the current traversal and straySlots(). The remaining concern is wording: the rule’s description should distinguish applying the allowed-child constraints to flattened content from strictly validating DOM content models. No code changes made.