Components: Generate Nav

[JasonVMo]

Summary

Generate Nav with its canonical contract, implementation, tests, stories, platform validation, and explicit package export so nested side navigation is available in the agentic library. The local spec is missing, and faithful delivery also depends on NavItem plus the shared roving-focus decision.

Observed. nav is entry nav in the canonical catalog and has no
implementation in packages/agentic/components. Upstream describes it as: Composed vertical side-navigation surface for moving between top-level destinations and nested sections. Covers type (Inline/Overlay), density, expandable categories, nested sub-items, selected-item indication, fixed width, hamburger collapse-to-hidden with no icon rail, and dependency delegation to NavItem, Button, and Divider.

Goal

Generate the nav component in
packages/agentic/components/src/components against the
canonical Fluent Flex spec, with the colocated coverage, stories, and platform
validation the package requires, and export it explicitly from
src/index.ts.

Stage

Stage 3 (production). Wave 3 - focus-orchestrated and composed.

Why it matters

Observed. The canonical catalog has 50 components and the agentic library has
generated 18. nav is one of the 32 in the gap, enumerated in
the missing-components index.

Inferred. It is a composed or focus-orchestrated component whose blockers resolve once the wave 2 overlay stack and the focus decision land, so it is a direct measure of whether those foundations were built correctly.

Observed current state

Canonical spec and source

Field	Value
Canonical spec	plugins/components/skills/nav/SKILL.md with usage.md, web/tokens.yaml, web/accessibility.md, and web/interaction.md, at x3-design/fluent-design @ d334acf
Upstream tier	molecule
Upstream catalog key	nav in component-map.yaml
Local staged spec	None. No specs/nav folder exists; the spec must be ingested first
Local implementation	None. No src/components/nav directory exists

Closest existing FURN or V1 implementation

• No navigation surface exists in any FURN catalog. The closest structural precedent is packages/components/Menu/src/MenuList, which orchestrates a vertical list of rows inside a FocusZone.

Note on platform canon. Where a legacy package has platform-specific files, the
desktop path (.win32, .windows, .macos, or the unsuffixed cross-platform file)
is the compatibility reference. .ios, .android, and .mobile variants are not
treated as the cross-platform canonical implementation.

Local dependencies

• src/components/divider - Observed present (component).
• src/components/button - Observed present (component).
• src/components/accordion - Observed present (component).

Known blockers

Observed. There is no recorded blocker, because there is no local spec folder and therefore no
blockers.md. The absence of an ingested spec is itself the first blocker; see
spec-ingestion-and-generation.md.

Scope

• Ingest or promote the spec into the component directory in the generated shape
  (SPEC.md plus a spec/ folder), per
  spec-ingestion-and-generation.md.
• Establish the public contract first: variants, slots, native props, accessibility,
  interaction states, and platform behavior.
• Implement the required file structure from
  src/components/AGENTS.md:
  nav.types.ts, nav.styles.ts, use*.ts, use*Styles.ts, render*.tsx, and
  the assembly module with a displayName.
• Style from Flex tokens first and record genuine token gaps rather than substituting
  unrelated values.
• Export the component, its public types, and the state, style, and render stages
  explicitly from src/index.ts under component-qualified unstable names.
• Depends on nav-item for the row contract.
• Decide whether expandable categories reuse the existing accordion component or implement their own disclosure.
• Own the selected destination and the roving-focus model, per the outcome of focus-zone.md.
• Keep the distinction from simple-nav explicit: Nav has hierarchy and no icon rail.

Out of scope

• Changing the contract of an existing generated component, unless this task explicitly
  calls for it above; raise it as its own item.
• Building shared infrastructure owned by another task: overlay hosting
  (popover), roving focus (focus-zone.md), spec
  ingestion (spec-ingestion-and-generation.md),
  or the coverage contract (component-test-strategy.md).
• Migrating any legacy FURN consumer onto this component.
• Mobile platform support; the applicable upstream companion is web, retargeted to
  React Native for Windows and macOS.

Deliverables

• src/components/nav/ implementing the full required file structure.
• SPEC.md and a spec/ companion folder with provenance recording the upstream path,
  SHA, and ingestion date.
• Colocated nav.test.tsx, nav.types.test.ts, and nav.stories.tsx.
• Snapshot coverage where the visual contract is state-dependent, or a recorded
  exemption.
• Explicit exports from src/index.ts, with src/index.test.ts updated.
• A changeset, per the repository's version management rules.
• A recorded readiness level with its supporting evidence.

Required coverage, stories, and platform validation

Runtime and type coverage:

• Both types, every density, expanded and collapsed categories, and nested sub-items.
• Selected indication and that selecting a destination is reported to the caller.
• Hamburger collapse to hidden, and that the host owns reopening.
• Keyboard navigation across items and categories.
• Navigation role, group structure, and the current-destination state.
• User style and handler forwarding, and that user styles are applied after component
  styles.
• Compile-time slot acceptance and any mutually exclusive props.

Stories: a typed Meta titled Components/Nav, an args-driven Default, a
grouped Overview when the contract has several axes, one focused story per variant
axis, and an interactive story for each stateful axis. Self-driving axes expose
default<State> as the control; externally driven selection is owned by the story with
React.useState. Identity-changing axes are not exposed as controls.

Platform validation: the component's stories render and behave correctly on macOS
and on React Native Windows Fabric through apps/storybook,
including hover, pressed, disabled, focus, optional-slot, and constrained-content
scenarios. Add a stable root testID if the component joins the automated smoke set.

Acceptance criteria

• src/components/nav exists with the required file structure and a displayName.
• Every variant axis in the component's SPEC.md is implemented, or a deviation is recorded in the spec.
• The component styles from Flex tokens, with any genuine token gap recorded rather than approximated.
• Focus feedback renders through FocusVisual; no outline* props and no React Native Windows native focus visuals are introduced.
• State precedence is explicit: disabled wins over pressed, which wins over hovered.
• Every stateful axis is classified as self-driving or externally driven, and both paths are covered.
• Runtime, type, and story coverage satisfy the package coverage contract.
• The component, its public types, and its pipeline stages are exported explicitly from src/index.ts, and src/index.test.ts covers them.
• The component's stories render on macOS and on React Native Windows Fabric.
• yarn workspace @fluentui-react-native/components format, lint, build, and test pass, and the Storybook bundle succeeds for both desktop platforms.
• A readiness level is recorded with its supporting evidence.
• A changeset is included.

Dependencies and ordering

• Blocked by spec-ingestion-and-generation.md: the spec must be pulled from the pinned upstream revision before generation can start.
• Blocked by wave 2, either directly or through a wave 2 dependency listed above.
• Gated by component-test-strategy.md: the component must satisfy the coverage contract on arrival rather than being retrofitted.
• Gated by readiness-model.md: the target readiness level must be stated before the work starts.
• Consumes the Infrastructure workstream (storybook-e2e.md) for automated macOS and Windows Fabric validation; until it lands, platform validation is manual.

Risks and open decisions

1. Nav and Simple Nav overlap substantially; deciding their shared internals before building either avoids a duplicated navigation stack.
2. It depends on both nav-item and the focus decision, so it is late in the ordering.

Evidence and references

• Upstream spec: plugins/components/skills/nav/SKILL.md and
  components-index/SKILL.md
  at x3-design/fluent-design @ d334acf.
• Canonical implementations to follow: src/components/button
  for a styled higher-order component and src/primitives/icon
  for a primitive.
• Authoring rules: src/components/AGENTS.md and the
  agentic component authoring skill.
• Workstream context: Components README and
  the missing-components index.

Sources retrieved 2026-08-20.