feat(04-03): register plugin mail layouts and publish the mailer at boot

- Map short layout names onto dotted layout files and wrap text/HTML
- party.Activate publishes postcard.Mailer before Boot and names missing files
- Hello plugin sends through the app-scoped mailer

Co-authored-by: Cursor <cursoragent@cursor.com>

examples/hello/hello_test.go

@@ -16,6 +16,7 @@ import (
 	"git.golem15.com/golem15/summercms/pact"
 	"git.golem15.com/golem15/summercms/party"
 	"git.golem15.com/golem15/summercms/phrasebook"
+	"git.golem15.com/golem15/summercms/postcard"
 	"git.golem15.com/golem15/summercms/surf"
 )
 
@@ -142,6 +143,35 @@ func TestHelloPluginResolvesLang(t *testing.T) {
 	}
 }
 
+func TestHelloPluginSendsMail(t *testing.T) {
+	cfg, err := compass.Load("config")
+	if err != nil {
+		t.Fatal(err)
+	}
+	app := backpack.New(cfg)
+	if _, err := party.Activate(app, []string{"golem15.hello"}); err != nil {
+		t.Fatal(err)
+	}
+	mail, ok := app.Lookup[postcard.Mailer]()
+	if !ok {
+		t.Fatal("mailer not published")
+	}
+	if err := mail.Send(t.Context(), postcard.Message{
+		Template: "golem15.hello::mail.hello",
+		To:       []string{"ada@example.test"},
+		Vars:     map[string]any{"Name": "Ada", "URL": "https://example.test"},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	if err := mail.Send(t.Context(), postcard.Message{
+		Template: "golem15.hello::mail.hello-en",
+		To:       []string{"ada@example.test"},
+		Vars:     map[string]any{"Name": "Ada", "URL": "https://example.test"},
+	}); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestTypedItemRoute(t *testing.T) {
 	cfg, err := compass.Load("config")
 	if err != nil {

examples/hello/plugins/base/plugin.go

@@ -10,8 +10,9 @@ import (
 )
 
 var (
-	_ pact.HasConfig = (*Plugin)(nil)
-	_ pact.HasLang   = (*Plugin)(nil)
+	_ pact.HasConfig        = (*Plugin)(nil)
+	_ pact.HasLang          = (*Plugin)(nil)
+	_ pact.HasMailTemplates = (*Plugin)(nil)
 )
 
 //go:embed config
@@ -20,6 +21,9 @@ var configFS embed.FS
 //go:embed lang
 var langFS embed.FS
 
+//go:embed views/mail
+var mailFS embed.FS
+
 // Plugin is the golem15.hello plugin.
 type Plugin struct{}
 
@@ -32,6 +36,19 @@ func (p *Plugin) Boot(*backpack.App) error     { return nil }
 func (p *Plugin) ConfigFS() fs.FS { return configFS }
 func (p *Plugin) LangFS() fs.FS   { return langFS }
 
+func (p *Plugin) MailTemplatesFS() fs.FS { return mailFS }
+func (p *Plugin) MailTemplates() []string {
+	return []string{
+		"golem15.hello::mail.hello",
+		"golem15.hello::mail.hello-en",
+	}
+}
+func (p *Plugin) MailLayouts() map[string]string {
+	return map[string]string{
+		"hello": "golem15.hello::mail.layouts.hello",
+	}
+}
+
 func init() {
 	party.Register(&Plugin{})
 }

examples/hello/plugins/base/views/mail/hello-en.htm

@@ -1,6 +1,6 @@
 subject = "Hello {{ .Name }}"
 description = "English hello greeting"
-layout = "default"
+layout = "hello"
 ==
 Hello **{{ .Name }}**.
 

examples/hello/plugins/base/views/mail/hello.htm

@@ -1,6 +1,6 @@
 subject = "Witaj {{ .Name }}"
 description = "Hello greeting"
-layout = "default"
+layout = "hello"
 ==
 Witaj **{{ .Name }}**.
 

examples/hello/plugins/base/views/mail/layouts/hello.htm

@@ -0,0 +1,14 @@
+name = "Hello"
+==
+-- {{ .Content }} --
+==
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
+<style type="text/css">{{ .brandCss }}{{ .css }}</style>
+</head>
+<body>
+<div class="layout-hello">{{ .Content }}</div>
+</body>
+</html>