One record answers another, from a list

Three small things that together make a board work: a link on every
listed record to a page about it (ResourceSpec.link, {id} and {field}
in the address); a state mail whose `to` is a field of the record this
one belongs to ({notice.email}), with that record's fields in the
text, and a lint that the form carries the record field it reaches
through; and value: "{user.email}" filled from the session and hidden,
so someone the site knows is not asked who they are.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GT37Z1Xtfd9pUuQtMTg6Yt

src/aggregates/mod.rs

@@ -55,11 +55,15 @@ pub struct AggregateSchema {
 
 /// A mail to send when a record enters a state. `to` is `submitter`
 /// (the record's `email` field, which the lint then requires the
-/// forms to collect) or one fixed address. Subject and body are
-/// templates: `{field}` for any field of the record, plus `{site}`
-/// (the instance's public URL), `{chain}` (the record id), `{email}`,
-/// `{bucket}` and `{state}`. The body is markdown; the mailer sends it
-/// as plain text with an HTML alternative.
+/// forms to collect), one fixed address, or a field of the record
+/// this one belongs to: `{notice.email}` when the form has a
+/// `type: record` field called `notice`. That is how an answer to a
+/// notice reaches whoever posted it. Subject and body are templates:
+/// `{field}` for any field of the record, `{notice.field}` for one of
+/// the record it belongs to, plus `{site}` (the instance's public
+/// URL), `{chain}` (the record id), `{email}`, `{bucket}` and
+/// `{state}`. The body is markdown; the mailer sends it as plain text
+/// with an HTML alternative.
 #[derive(Clone, Debug, PartialEq, serde::Serialize, serde::Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct MailSpec {