Phase 5: reply drafts — template/LLM draft, edit, SMTP send (AUD-71)

Implements Phase 5 of AGENTS.md §11 (FR-8, FR-15):

- Message detail pane (GET /partials/message) with body, recommended
  action, reply identity, template picker, editable draft, and history.
- internal/reply: OmniRoute (OpenAI-compatible) chat client and a
  template-based draft generator. All non-JEV models go through
  OmniRoute (§10).
- internal/mailops: SMTP send over smtp.gmail.com:587 with STARTTLS and
  the app password, forcing IPv4 (§9); FR-15 reply identity (send as the
  arrived-at X-Pm-Original-To address, else "Sam Rolfe"); threading via
  In-Reply-To/References; -check-smtp safe verification; and a
  [Gmail]/Sent Mail thread check.
- Migration v5 stores messages.message_id_header and drafts.sent_at;
  mailfetch parses Message-ID.
- Send is user-triggered only: CSRF + UI confirm + confirm=yes guard,
  no auto-send, duplicate-send refused. A sent reply files the original
  under Replied-to/<address> and logs every step (FR-13).
- Tests for reply, mailops SMTP/identity/thread check, store drafts and
  migration v5, and the server draft/edit/send guards.
- docs/phase5-replies.md, README, .env.example, docker-compose updated.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

internal/reply/draft_test.go

@@ -0,0 +1,118 @@
+package reply
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/store"
+)
+
+func TestTemplateForAction(t *testing.T) {
+	if got := TemplateForAction("reply").ID; got != "answer" {
+		t.Errorf("TemplateForAction(reply) = %q, want answer", got)
+	}
+	if got := TemplateForAction("keep").ID; got != "quick-ack" {
+		t.Errorf("TemplateForAction(keep) = %q, want quick-ack", got)
+	}
+	if _, ok := TemplateByID("DECLINE"); !ok {
+		t.Error("TemplateByID should match case-insensitively")
+	}
+	if _, ok := TemplateByID("nonsense"); ok {
+		t.Error("TemplateByID should reject an unknown template")
+	}
+}
+
+func TestBuildPromptIncludesContext(t *testing.T) {
+	req := Request{
+		Message: store.Message{
+			FromAddr:      "customer@example.test",
+			SourceAddress: "hello@where-woof.com",
+			Subject:       "Booking for Saturday",
+			BodyText:      "Can we book Saturday at 10?",
+		},
+		Category:    "Action",
+		Importance:  "high",
+		Action:      "reply",
+		Instruction: "Confirm 10am works",
+		Signer:      "Sam",
+	}
+	tmpl, _ := TemplateByID("confirm")
+	system, user := BuildPrompt(req, tmpl)
+
+	if !strings.Contains(system, "Return only the reply body") {
+		t.Errorf("system prompt missing the output constraint: %q", system)
+	}
+	for _, want := range []string{
+		"Confirm an arrangement",
+		"Confirm 10am works",
+		"category=Action",
+		"importance=high",
+		"suggested_action=reply",
+		"customer@example.test",
+		"hello@where-woof.com",
+		"Booking for Saturday",
+		"Can we book Saturday at 10?",
+	} {
+		if !strings.Contains(user, want) {
+			t.Errorf("user prompt missing %q\n%s", want, user)
+		}
+	}
+}
+
+func TestCleanDraftStripsFenceAndSubject(t *testing.T) {
+	if got := cleanDraft("```\nHello there.\n```", 1000); got != "Hello there." {
+		t.Errorf("cleanDraft fence = %q", got)
+	}
+	if got := cleanDraft("Subject: Re: hi\n\nHello there.", 1000); got != "Hello there." {
+		t.Errorf("cleanDraft subject = %q", got)
+	}
+}
+
+func TestGeneratorDraftUsesTemplate(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_ = json.NewEncoder(w).Encode(chatResponse{
+			Choices: []struct {
+				Message chatMessage `json:"message"`
+			}{{Message: chatMessage{Role: "assistant", Content: "Sure, Saturday works.\n\nSam"}}},
+		})
+	}))
+	defer srv.Close()
+
+	g := NewGenerator(NewClient(srv.URL, "key", "auto/best-chat", slog.New(slog.DiscardHandler)),
+		slog.New(slog.DiscardHandler))
+	body, templateID, err := g.Draft(context.Background(), Request{
+		Message: store.Message{FromAddr: "a@b.test", Subject: "hi", BodyText: "?"},
+		Action:  "reply",
+	})
+	if err != nil {
+		t.Fatalf("Draft() error = %v", err)
+	}
+	if templateID != "answer" {
+		t.Errorf("template = %q, want answer (the default for action=reply)", templateID)
+	}
+	if !strings.Contains(body, "Saturday") {
+		t.Errorf("body = %q", body)
+	}
+}
+
+func TestGeneratorDraftEmptyReplyIsAnError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_ = json.NewEncoder(w).Encode(chatResponse{
+			Choices: []struct {
+				Message chatMessage `json:"message"`
+			}{{Message: chatMessage{Role: "assistant", Content: "   "}}},
+		})
+	}))
+	defer srv.Close()
+
+	g := NewGenerator(NewClient(srv.URL, "key", "m", slog.New(slog.DiscardHandler)),
+		slog.New(slog.DiscardHandler))
+	if _, _, err := g.Draft(context.Background(), Request{Message: store.Message{Subject: "x"}}); err == nil {
+		t.Fatal("Draft() error = nil, want an error for an empty reply")
+	}
+}