fix(firestore-send-email): kit/extension parity – a required placeholder SMTP_PASSWORD overrides the password in SMTP_CONNECTION_URI #3293

firestore-send-email kit/extension parity. Priority: high. After migrating, every email fails to send if the SMTP password was kept in the connection URI.

Difference

• Extension: SMTP_PASSWORD is optional. Installs that put the password in SMTP_CONNECTION_URI (the "backwards compatible" form in the param's description) have no secret, and the URI's password is used.
• Kit:
  • All four secrets are always bound, so SMTP_PASSWORD must exist and must not be empty. ext:migrate and functions:kits:install prompt for it, and Secret Manager rejects an empty value.
  • Any non-blank value then replaces the URI's password, the same as in the extension.
  • Users who enter a placeholder (the README recommends placeholders for the unused secrets) get an authentication failure on every send. A placeholder also adds auth to SMTP relays that need none.

Reproduced

1. Extension installed with SMTP_CONNECTION_URI=smtp://user:pass@smtp.ethereal.email:587 and no SMTP_PASSWORD: mail sends (SUCCESS).
2. firebase ext:migrate on that instance: it prompts "Enter a value for SMTP password". An empty answer fails with Secret Payload cannot be empty, so "placeholder" was entered.
3. The migrated kit fails every document with delivery.error: "Error: Invalid login: 535 Authentication failed". A README-setup kit with the same URI and a placeholder secret fails the same way.
4. Setting the secret to a single space works around it: the kit trims it to unset, and mail sends.

Code

• Extension:
  • extension.yaml#L212-L244 (URI with an inline password, and SMTP_PASSWORD with required: false)
  • helpers.ts#L61-L68
• Kit:
  • all four secrets bound: index.ts#L70, #L114, config.ts#L307-L312
  • the override: helpers.ts#L93-L99
  • the trim: export-config.ts#L95-L98
  • README: README.md#L157-L169

Resolution

• Only use SMTP_PASSWORD when the URI carries no password of its own. That is a behaviour change only for configs that set both.
• Or, at a minimum, document in the README and the migration notes: move an inline password into SMTP_PASSWORD, or set that secret to a single space.