Adopt Selector in one member

What is different this time

The three previous adoption loops verified by rendering and measuring. That worked because Button, Chip and CardRow are appearance with a little behaviour, so a defect shows up as wrong pixels.

Selector is behaviour with a little appearance. A broken keyboard renders perfectly. Three primitives already shipped defects that passed every gate — one made its own button unfocusable while reporting tabIndex="0" and a correct accessible name.

So the test comes before the refactor, and it is the load-bearing step.

The loop

flowchart TD
    Start([Member assigned]) --> Read[Read the spec, the plan,<br/>and this loop]
    Read --> Find["Identify the custom code<br/>Selector replaces"]
    Find --> GH["Open a gh issue<br/>body links the context-v plan"]
    GH --> Red["Write a test that FAILS<br/>against the member's CURRENT markup"]
    Red --> Verify{Does it fail<br/>for the RIGHT reason?}
    Verify -->|"No — passes, or errors"| Red
    Verify -->|"Yes"| Refactor[Refactor onto Selector]
    Refactor --> Green{Test passes?<br/>Gates hold?}
    Green -->|No| Refactor
    Green -->|Yes| Discover["Write discoveries into<br/>context-v/issues/"]
    Discover --> Report[Report to the VP of Eng]
    Report --> Ver{Verified?}
    Ver -->|"Findings disputed"| Refactor
    Ver -->|"Yes"| Log[Changelog beat]
    Log --> Commit([Commit + push])

Step 4 is the one people get wrong

A test that fails because the component is missing is not the test. It has to fail against the member's current markup, describing the defect that is shipping today:

• the ArrowDown that moves nothing

• the option that has no tabindex="-1", so the widget is N tab stops

• the role="menu" with no menuitem children

• the role="radiogroup" with no radios

Run it. Read the failure. If it fails for a reason other than the defect you meant to describe, the test is wrong — fix the test before touching the member.

This is also the only way to prove the nine surfaces were genuinely broken rather than merely undocumented. A refactor with no red phase produces a green test and proves nothing.

What you are adopting

MenuItem is the presentational row — icon, label, shortcut, danger tone. The Selector owns the keyboard; MenuItem owns the appearance. Same split as ListContainer and CardRow.

There is no Selector--Radio. Zero radios in the federation; shipping ahead of consumers is how the federal layer got a spacing scale with no adopters.

The contract you are inheriting

Seventeen tests already assert it in packages/shared-ui/test/selector.test.ts. You do not re-test the component — you test that your member uses it.

1. One tab stop for the widget, not one per option.

2. Arrows move the active option, and focus follows.

3. Home / End, and typeahead on a printable character.

4. Enter / Space activate. Escape closes a popup and returns focus to its trigger.

5. The role triad is consistent — never a container role with the wrong children.

Judgement

• A menu is actions; a listbox is choices. If the thing has a selected state, it is a listbox even when it is drawn as a popdown.

• A combobox is not either of these. An input that filters a list is a third organ with its own contract. If your surface has a text input driving the list, leave it and raise it — do not force it.

• Escape must return focus to the trigger, not to <body>. A popup that drops focus is worse than one that never opened.

• Do not invent a keyboard where none was promised. A plain list of buttons with no role is not broken — it is a list of buttons. Only adopt where a composite role is already declared, or where the surface genuinely is one.

Inherited, not repeated

Everything mechanical comes from Adopt The Shared Button In One Member — probe recipe, resolve.alias (NEVER source.alias) with the mandatory sentinel grep, gate capture, raise-don't-chase, and the ladder. Rung 4 is style=, not class=.

Gates

pnpm --filter <pkg> test                     # your new test, green
node scripts/design-drift.mjs --member <p>   # must not increase
pnpm --filter <pkg> check                    # 0 errors
pnpm --filter <pkg> build
node scripts/verify-federation.mjs --fast    # must stay clean

Related

• Build Selector And Close The Keyboard Contract — the plan

• The List Surface Paradigm CardRow ListContainer And Selection — D4

• Adopt The Shared Button In One Member — the mechanical half

• From a Raised Issue to Fixed and Shipped — the gh-issue-to-shipped cadence this mirrors