fix(ui): label the login field "Username or email" to match the backend

[jianyx1]

The login form labels its first field "Email address", but the backend
@cl.password_auth_callback receives any username string, and the docs
use username — users are confused when the UI says "Email" while the
backend accepts any string.

Align the UI with the backend:

• relabel the field "Username or email" in all 23 locale files
• update the required-field message to match
• rename the frontend's email identifiers to username
  (the request payload already sends username, so nothing changes
  on the wire)

The placeholder "me@example.com" is left unchanged: it is a format
example, not a restriction.

Non-English strings follow each locale file's existing wording and may
need native-speaker review.

Verification:

• cd backend && uv run pytest --cov=chainlit → 932 passed
• cd frontend && pnpm test → 32 passed (5 files)
• pnpm type-check → frontend + react-client pass
• pnpm lint on the changed files → clean

Closes #2902

Co-Authored-By: Claude noreply@anthropic.com

---

Summary by cubic

Relabels the login form's first field from "Email address" to "Username or email" so the UI matches the backend, which accepts any username string. The request payload already sends username, so nothing changes on the wire.

• Updates the label and required-field message in all 23 locale files.
• Renames the frontend's email identifiers to username, including the input's id/name attributes.
• Updates all Cypress selector references to match the renamed field.
• Leaves the placeholder me@example.com unchanged as a format example.
• Non-English strings follow each locale's wording and may need native-speaker review.

Closes #2902.

^{Written for commit 739365b. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 25 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="frontend/src/components/LoginForm.tsx">

<violation number="1" location="frontend/src/components/LoginForm.tsx:109">
P2: Renaming the input's id from `email` to `username` breaks the Cypress e2e login flow in cypress/e2e/data_layer/spec.cy.ts:8, which still selects `#email` (`cy.get(SELECTORS.EMAIL_INPUT)` at line 35). This repo's verification (pnpm test / type-check / lint) doesn't cover Cypress, so the break ships unnoticed. Update the spec's SELECTORS.EMAIL_INPUT to `#username` (or keep the id stable) in the same change.</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

P2: Renaming the input's id from email to username breaks the Cypress e2e login flow in cypress/e2e/data_layer/spec.cy.ts:8, which still selects #email (cy.get(SELECTORS.EMAIL_INPUT) at line 35). This repo's verification (pnpm test / type-check / lint) doesn't cover Cypress, so the break ships unnoticed. Update the spec's SELECTORS.EMAIL_INPUT to #username (or keep the id stable) in the same change.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At frontend/src/components/LoginForm.tsx, line 109:

<comment>Renaming the input's id from `email` to `username` breaks the Cypress e2e login flow in cypress/e2e/data_layer/spec.cy.ts:8, which still selects `#email` (`cy.get(SELECTORS.EMAIL_INPUT)` at line 35). This repo's verification (pnpm test / type-check / lint) doesn't cover Cypress, so the break ships unnoticed. Update the spec's SELECTORS.EMAIL_INPUT to `#username` (or keep the id stable) in the same change.</comment>

<file context>
@@ -102,24 +102,26 @@ export function LoginForm({
               </Label>
               <Input
-                id="email"
+                id="username"
                 disabled={loading}
                 autoFocus
</file context>

[github-actions]

This PR is stale because it has been open for 14 days with no activity.