Add strata_link_to and strata_button_to view helpers

[MichaelCrawfordNava]

Changes

• Adds Strata::LinksHelper with strata_link_to. Defaults to a pure passthrough to Rails' link_to. Pass as: :button to opt into USWDS button styling, with the same :variant, :size, :inverse keywords as ButtonComponent.
• Adds Strata::ButtonsHelper with strata_button_to. Wraps Rails' button_to and always applies USWDS button styling — button_to is unambiguously about producing a CSRF-protected form-wrapped button.
• Both modules included via Strata::ApplicationHelper so the helpers are auto-available in any view rendered by Strata-using controllers.
• New docs/strata-view-helpers.md with full usage docs.
• Registers the new doc in docs/README.md and CLAUDE.md.
• docs/uswds-components.md "Button" section now cross-links to the new helpers doc.
• Updates ButtonComponent / ButtonGroupComponent doc comments to mention the helpers.

Context

Ergonomic wrappers around Rails' link/button primitives. They use Strata::US::ButtonComponent.css_classes (introduced in the parent PR) as the single source of truth for class strings — so the FormBuilder, the helpers, and any direct caller all produce the same output.

Design notes worth flagging for reviewers:

• Why strata_link_to has an :as switch and a passthrough default. An earlier iteration had strata_link_to always apply button styling, which was misleading — `link_to` shouldn't always imply button. The :as discriminator makes the styling explicit and leaves room for future treatments (e.g., as: :external).
• Why two modules instead of one. `strata_link_to` has a passthrough mode that produces a plain link, so it doesn't belong in a "Buttons" module. Splitting by topic matches the engine's existing one-module-per-helper pattern (DateHelper, CasesHelper, TasksHelper).
• Why there's no strata_button_link_to / strata_link_to_button. `strata_link_to ..., as: :button` covers the button-styled-link case. Avoiding a third helper keeps the surface area small.
• Validation behavior: strata_link_to raises ArgumentError when :variant / :size / :inverse are passed without as: :button. Catches the "forgot to opt in" mistake; without this check the styling would silently disappear. Also raises on an unrecognized :as value (currently :button is the only allowed treatment).

This PR stacks on #358 (cael/uswds-button-component). The follow-up adoption PR on top migrates all existing call sites to use these helpers.

Testing

$ make lint-ci
355 files inspected, no offenses detected

$ make test
1401 examples, 0 failures

Test plan:

• bundle exec rspec spec/helpers/strata/links_helper_spec.rb — 14 examples cover passthrough mode (plain link, html_options forwarding, block form), as: :button mode (each modifier, class merging, html_options, block form, invalid variant), and the validation paths (variant/size/inverse without :as, unknown :as).
• bundle exec rspec spec/helpers/strata/buttons_helper_spec.rb — 8 examples cover the rendered form/button structure, each modifier, class merging, preserved button_to options (:method, :params), validation, and that the output class string matches ButtonComponent.css_classes for the same keywords.

[Copilot]

Pull request overview

Adds Strata view-helper wrappers around Rails link_to / button_to to standardize USWDS button styling via Strata::US::ButtonComponent.css_classes, with accompanying documentation and helper specs.

Changes:

• Introduces Strata::LinksHelper#strata_link_to (passthrough by default; as: :button opt-in styling + validation).
• Introduces Strata::ButtonsHelper#strata_button_to (always USWDS-styled) and includes both helpers via Strata::ApplicationHelper.
• Adds/updates docs and RSpec coverage for the new helpers, and refreshes component doc comments to reference them.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
spec/helpers/strata/links_helper_spec.rb	Adds RSpec coverage for strata_link_to passthrough, button treatment, class merging, and validation.
spec/helpers/strata/buttons_helper_spec.rb	Adds RSpec coverage for strata_button_to structure, modifiers, option forwarding, and css class parity.
docs/uswds-components.md	Updates Button docs to point to the new helpers and clarifies when to use css_classes.
docs/strata-view-helpers.md	New documentation page describing strata_link_to / strata_button_to usage and behavior.
docs/README.md	Registers the new view helpers documentation in the docs index.
CLAUDE.md	Adds the new view helpers doc to the SDK-specific docs table.
app/helpers/strata/links_helper.rb	Implements strata_link_to with as: treatments and argument validation.
app/helpers/strata/buttons_helper.rb	Implements strata_button_to wrapper applying ButtonComponent.css_classes.
app/helpers/strata/application_helper.rb	Includes the new helper modules so they’re available in Strata views.
app/components/strata/us/button_group_component.rb	Updates inline example to use strata_link_to ..., as: :button.
app/components/strata/us/button_component.rb	Updates doc comments to reference the new helpers and positioning of css_classes.

[lamroger-nava]

I'm cool with this - are there any places we can use this immediately? Oh nvm - it's in the next PR

[MichaelCrawfordNava]

@claude will you please merge main into this branch and resolve conflicts?

[claude]

Claude finished @MichaelCrawfordNava's task in 4m 3s —— View job

---

Merged origin/main into cael/uswds-button-helpers

• Fetch latest from origin (had to --unshallow first — initial fetch was shallow with no common ancestor)
• Merge origin/main into the branch
• Resolve conflicts in 4 files
• Run make lint-ci — clean (355 files, 0 offenses)
• Run make test — green (1401 examples, 0 failures)
• Push merge commit 374de10

Conflict resolutions

Main brought in #358 as a single squashed commit (3e34ee2 Add uswds button and buttongroup components) that overlapped with this branch's button work. Resolutions:

• app/components/strata/us/button_component.rb — docstring-only conflict. Kept HEAD: it documents the new strata_link_to / strata_button_to helpers added in this PR, which is the whole point.
• app/components/strata/us/button_group_component.rb — docstring-only conflict in the @example. Kept HEAD: shows the new strata_link_to ..., as: :button form.
• app/previews/strata/us/button_group_component_preview.rb — adopted origin/main's template-backed approach. Main moved from inline html_safe class-string examples to sibling default.html.erb / segmented.html.erb templates (which were also added by the merge), because nested render calls don't work inside slot blocks in a Lookbook preview method. The template approach is cleaner and uses ButtonComponent directly.
• docs/uswds-components.md — kept HEAD's helper-aware structure (recommends helpers for link_to/button_to, css_classes for form.button / f.submit), and brought back the FormBuilder#submit example block from origin/main since that detail is still accurate and useful.
  • Branch: cael/uswds-button-helpers • Merge commit: 374de10