Components: Generate Textarea

Summary

Generate Textarea with its canonical contract, implementation, tests, stories, platform validation, and explicit package export so multiline entry is covered. Input patterns are available, but the staged spec must first be retargeted for unsupported web resize axes and React Native multiline accessibility behavior.

Observed. textarea is entry textarea in the canonical catalog and has no
implementation in packages/agentic/components. Upstream describes it as: Multi-line text entry control for longer free-form content. Covers resize behavior (None, Vertical, Both) and seven states including Focus, Error, and Read only.

Goal

Generate the textarea 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 2 (beta). Wave 1 - local component dependencies already generated.

Why it matters

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

Inferred. The generated input dependency exists, but implementation is
gated on the shared spec-retargeting decision for the web-only resize axis and
multiline accessibility contract.

Observed current state

Canonical spec and source

Field	Value
Canonical spec	plugins/components/skills/textarea/SKILL.md with usage.md, web/tokens.yaml, web/accessibility.md, and web/interaction.md, at x3-design/fluent-design @ d334acf
Upstream tier	atom
Upstream catalog key	textarea in component-map.yaml
Local staged spec	packages/agentic/components/specs/textarea - SPEC.md, usage.md, interaction.md, accessibility.md, tokens.yaml, blockers.md
Local implementation	None. No src/components/textarea directory exists

Closest existing FURN or V1 implementation

• packages/components/Input - Input.tsx, useInput.ts, Input.styling.ts, and InputTokens.ts are the desktop path. No multiline variant exists in this package; Input.ios.tsx, Input.android.tsx, and Input.mobile.tsx are mobile-only.

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/input - Observed present (component).

Known blockers

Observed (blockers.md, blocker class C in the index).

Three blockers were recorded: the spec's Resize axis (none | vertical | both) and its native resize handle have no cross-platform React Native equivalent on macOS or Windows; the accessibility contract is written around native <textarea> semantics and aria-multiline; and no agentic multi-line text control existed to extend.

Reassessment.

Partly stale. The third premise is gone: src/components/input now exists and is the natural base. The resize-handle gap is genuine. Inferred: implementable once the spec records the missing resize-handle parity, which is the decision the blocker file itself proposes.

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:
  textarea.types.ts, textarea.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.
• Take the spec decision the blocker file asks for: implement a React Native approximation that drops exact resize-handle parity, and record the deviation in the component spec.
• Decide whether Vertical resize is expressed as a growing content height rather than a drag handle, since React Native TextInput has no handle.

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/textarea/ implementing the full required file structure.
• SPEC.md and a spec/ companion folder with provenance recording the upstream path,
  SHA, and ingestion date.
• Colocated textarea.test.tsx, textarea.types.test.ts, and textarea.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:

• Every one of the seven states, including Focus, Error, and Read only.
• Whatever subset of the Resize axis is implemented, plus an assertion that unsupported values are rejected or documented.
• Multi-line accessibility state on macOS and Windows Fabric.
• Controlled and uncontrolled value paths.
• Long content with a constrained container.
• 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/Textarea, 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/textarea 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

• 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. Auto-growing height on React Native Windows Fabric can cause layout thrash and needs on-device verification.
2. Dropping the resize handle is a visible contract deviation and should be recorded in the drift report, not hidden.

Evidence and references

• Upstream spec: plugins/components/skills/textarea/SKILL.md and
  components-index/SKILL.md
  at x3-design/fluent-design @ d334acf.
• Local staged spec and blocker record: packages/agentic/components/specs/textarea.
• 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.

Start with packages/agentic/components/specs/textarea/SPEC.md and blockers.md, then read src/components/AGENTS.md and the existing src/components/input implementation. Resolve and record the resize and multiline accessibility decisions before implementing the required textarea files, tests, stories, exports, and changeset. Done means the listed runtime, type, story, platform, build, lint, and test checks pass.