Migrate Mail surfaces to interface patterns

docs/MAIL_HANDBOOK.md

@@ -43,6 +43,25 @@ session primitives, cryptographic secret helpers, audit infrastructure, and the
 module registry. Optional consumers provide narrow context through capabilities;
 Mail does not import their ORM or service implementations.
 
+## Interface patterns and unavailable actions
+
+Mail uses the platform's shared explorer, connection tree, adaptive form,
+effective-policy, dialog, status, alert, and confirmation components. The
+module-owned surface inventory and consequence classification are recorded in
+[Mail interface pattern migration](INTERFACE_PATTERN_MIGRATION.md).
+
+An unavailable action remains visible when it belongs to the current task. Its
+hover/focus explanation identifies the missing field, active operation, or
+permission. Larger blockers state what must change, who can change it, and
+where to go. Contextual Help Center links resolve to the configured Docs module
+when installed and otherwise use the public documentation fallback.
+
+Mailbox reads, profile reloads, connection tests, policy saves, bounce scans,
+and destructive actions each expose their current loading or blocked state.
+Removing a bounce watcher and deactivating profile hierarchy items use shared
+confirmation dialogs. Removing a watcher retains existing observations;
+deactivating a profile may scrub Mail-owned credentials as described below.
+
 ## Concepts
 
 ### Profile