Connect and store a mail account

[Hohnik]

Parent

Spec: MailChat MVP — email-as-chat

What to build

As a user, I can connect an IMAP/SMTP mailbox to MailChat by providing my address and app-specific password, and see it listed as a connected, validated account. Credentials are encrypted at rest using a master key sourced from the environment; the connection is validated against the real mail server (reusing the already-built, live-verified IMAP/SMTP clients) before the account is considered connected. Supports connecting more than one account to the same instance.

Acceptance criteria

• An Account model (provider/host/port/address) and a linked Credentials model exist, with credentials encrypted at rest (Fernet-style) using a master key read from an environment variable — never stored in the database.
• A connect service validates the supplied credentials against the real IMAP and SMTP servers (reusing the existing imap_client/smtp_client connect functions) before persisting the account as connected; a disconnect operation removes/deactivates an account.
• A minimal htmx-rendered form lets a user submit an account's address, host/port config, and app-specific password, and lists currently connected accounts.
• Connecting more than one account works — each is stored and listed independently.
• After IMAP verification succeeds, the connect flow lists the account's IMAP folders (reusing imap_client.list_folders) and lets the user pick which one is their Sent folder from that list — no free-text entry, no auto-detection/guessing. The selection is stored as a new Account.sent_folder field, defaulting to "Sent" only as the pre-selected option in the picker (not silently assumed if the user doesn't have a folder called that). (Decided in Decide reply send-from account and how sent replies re-enter the conversation — needed so sync can poll Sent per account; see Group messages into person+subject conversations and Reply within a conversation.)
• Tests: encrypt/decrypt round-trip unit test (no mocking); connect-service tests mocking the IMAP/SMTP connection boundary (same pattern as existing imap_client/smtp_client tests) covering both successful and failing credentials; an htmx route test (FastAPI TestClient) asserting the add-account form renders and a submitted account appears in the connected-accounts list.
• Tests: connect-flow test covering the new folder-picker step — asserting the folder list is shown after verification and the selected folder is persisted as Account.sent_folder.

Blocked by

• None — can start immediately

[Hohnik]

Reopened: Decide reply send-from account and how sent replies re-enter the conversation decided that reply mail can re-enter a conversation via anything sent through the account (not just MailChat itself), so sync needs to poll a Sent folder per account. That requires knowing each account's Sent folder name, which is now an added connect-flow step (folder list → user picks Sent) rather than assumed. See #16 for the full reasoning.