fix(frontend): add list instance emails endpoint and Select in AddUser

[claude]

Summary

• Add a GET /w/{workspace}/users/list_instance_emails endpoint that returns all instance user emails (requires workspace admin, disabled on cloud)
• Enhance the "Add user" popover in workspace settings with an AutocompleteSelect dropdown that suggests existing instance users not yet in the workspace
• Users can select from the dropdown or type a custom email — value syncs live as they type
• Falls back to a plain TextInput on cloud or if the endpoint fails
• Add client-side email validation with InputError

Closes #7902

Changes

Backend

• New list_instance_emails endpoint in windmill-api-users that queries emails from the password table (sorted alphabetically). Disabled on cloud-hosted instances. Requires workspace admin.
• OpenAPI spec updated with the new endpoint definition.
• SQLX offline query cache updated.

Frontend

• New AutocompleteSelect.svelte: A dedicated component for the "type anything, value syncs live" use case. Reuses SelectDropdown and processItems from the existing select infrastructure. Keeps the widely-used Select component unchanged.
• AddUser.svelte: On non-cloud instances, fetches instance emails and renders an AutocompleteSelect (with type-to-filter and custom email support). Falls back to TextInput on cloud or if the endpoint fails. Existing workspace members are filtered out. Email validation added.
• WorkspaceUserSettings.svelte: Passes current workspace member emails to AddUser for filtering.
• Select.svelte: Minor fix — on:close to onClick on CloseButton (Svelte 5 migration).
• Regenerated OpenAPI TypeScript client.

Screenshot

Test plan

• On a non-cloud instance, open Workspace Settings > Users, click "Add new user" and verify an autocomplete dropdown appears
• Verify the dropdown only shows instance users that are not already workspace members
• Verify typing filters the list and a custom email can be typed directly
• Verify email validation shows an error for invalid emails
• On a cloud instance, verify the plain email input still appears
• Verify existing Select usages (e.g. DBManager schema select) are unaffected

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View logs

[windmill-internal-app]

🤖 Updated ee-repo-ref.txt to c927593b0b49867284fc64d50c59daba6c70da84 after windmill-ee-private PR #415 was merged.

[claude]

Claude finished @Guilhem-lm's task in 2m 28s —— View job

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Review Summary

• Read all changed files
• Review backend changes (Rust endpoint, SQL, OpenAPI)
• Review frontend changes (AutocompleteSelect, AddUser, etc.)
• Post inline comments for specific issues
• Write final review summary with testing instructions

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Overview

This PR adds an autocomplete dropdown for the "Add user" flow in workspace settings, backed by a new backend endpoint that returns all instance user emails. The approach is reasonable: a new list_instance_emails endpoint, a new AutocompleteSelect component, and a graceful fallback to plain text input on cloud instances or failure.

What works well

• Clean separation: Creating AutocompleteSelect as a separate component rather than adding free-text mode to the existing Select avoids regressions on the widely-used Select.
• Graceful degradation: Falls back to TextInput on cloud or API failure.
• Filtering out existing members: The workspaceSet approach in instanceEmails is efficient.
• Email validation: Simple and effective client-side check.
• Select.svelte fix: The on:close → onClick change is correct for Svelte 5 migration.

Issues to address

See inline comments for detailed feedback on each file. The main points:

1. No pagination on the backend endpoint — SELECT email FROM password ORDER BY email returns all instance emails unbounded. On large instances (thousands of users), this could be a large payload. Consider adding a LIMIT.

2. UI flash on load — The component shows TextInput first, then switches to AutocompleteSelect once the API call resolves. This creates a visible layout shift. A loading state would smooth this transition.

3. Noisy email validation — Since AutocompleteSelect syncs value on every keystroke, the email validation error flickers as the user types to filter (e.g., "ad" → error → "admin@..." → no error). Consider debouncing or only validating after the dropdown closes.

4. Top-level loadInstanceEmails() call — Called during component initialization with $workspaceStore! non-null assertion. If workspaceStore isn't populated yet, this could error silently (caught by try/catch, but means no autocomplete).

5. Minor: $effect interaction in AutocompleteSelect — Two effects interact in a subtle way around filterText and open state. A clarifying comment would help maintainability.

None of these are blocking — the code works correctly in the happy path. Items 1-3 are the most impactful for polish.

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How to test

On a non-cloud Windmill instance, go to Workspace Settings (gear icon → Members tab). Click the "Add new user" button in the top-right corner. An autocomplete dropdown should appear instead of a plain text input. The dropdown should list all instance users that are not already members of the current workspace. Typing in the field should filter the list, and you should also be able to type a custom email that doesn't appear in the dropdown. Entering an invalid email (e.g., "notanemail") should show a validation error below the field, and the "Add" button should be disabled. On a cloud-hosted instance (or if the endpoint fails), the plain email text input should appear instead.

[windmill-internal-app]

🤖 Updated ee-repo-ref.txt to 592848d59ca2304926fb2bd85d000668a7f46a77 after windmill-ee-private PR #420 was merged.