fix(firestore-send-email): kit/extension parity – invalid .env values leave mail unprocessed or silently change behaviour #3295

firestore-send-email kit/extension parity. Priority: medium. Some bad or blank settings in .env stop mail without any ERROR state. Others silently change behaviour. The extension rejected all of these at install.

Difference

• Extension: the platform rejects values outside a select list or regex, and fills blank optional params with their defaults.
• Kit: values read from .env are never checked (only prompt answers are), and the runtime coerces them:

The README says a bad value "fails at send time with delivery.state: ERROR". That isn't true for the first two rows.

Reproduced

• TTL_EXPIRE_TYPE=days and a blank SMTP_CONNECTION_URI were each deployed on a kit instance. Documents written afterwards never got a delivery field, and the logs above appeared on every call.
• Extensions validateOnly rejected days, 0, abc and oauth2.
• The other rows come from running the kit's config code and the CLI's .env parser locally.

Code

• Extension: extension.yaml#L198-L210, #L262-L274, #L356-L392
• Kit:
  • TTL throw: handlers.ts#L64, called inside the PENDING transaction at #L185
  • startup retried on every call: index.ts#L82-L106
  • || 1: export-config.ts#L115
  • TLS fallback: helpers.ts#L44-L52
  • README: README.md#L235-L246

Resolution

Validate select and int values once at startup, the way assertRequiredParams handles blanks, and fail loudly. That covers TTL_EXPIRE_TYPE, TTL_EXPIRE_VALUE, AUTH_TYPE, OAUTH_SECURE and a blank URI under UsernamePassword. Correct the README section, and tell users to single-quote JSON values in .env.