feat(auth): conversation_view preference, on by default

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

migrations/0018_conversation_view_preference.down.sql

@@ -0,0 +1 @@
+ALTER TABLE mailboxes DROP COLUMN IF EXISTS conversation_view;

migrations/0018_conversation_view_preference.up.sql

@@ -0,0 +1,3 @@
+-- Whether the webmail lists mail as conversations. On by default: it is what
+-- people coming from other mail programs expect, and it is one switch away.
+ALTER TABLE mailboxes ADD COLUMN conversation_view BOOLEAN NOT NULL DEFAULT true;

services/auth/src/repository.ts

@@ -1195,21 +1195,32 @@ export async function deleteAlias(scope: AdminScope, aliasId: string): Promise<b
 
 // ------------------------------------------------ user preferences & sieve
 
-export async function getUserPreferences(mailboxId: string): Promise<{ signature: string; auto_save_drafts: boolean }> {
-  const row = await queryOne<{ signature: string | null; auto_save_drafts: boolean | null }>(
-    `SELECT signature, auto_save_drafts FROM mailboxes WHERE id = $1`,
+export async function getUserPreferences(
+  mailboxId: string,
+): Promise<{ signature: string; auto_save_drafts: boolean; conversation_view: boolean }> {
+  const row = await queryOne<{ signature: string | null; auto_save_drafts: boolean | null; conversation_view: boolean | null }>(
+    `SELECT signature, auto_save_drafts, conversation_view FROM mailboxes WHERE id = $1`,
     [mailboxId],
   );
   return {
     signature: row?.signature ?? "",
     auto_save_drafts: row?.auto_save_drafts ?? true,
+    conversation_view: row?.conversation_view ?? true,
   };
 }
 
-export async function updateUserPreferences(mailboxId: string, signature: string, autoSaveDrafts: boolean): Promise<boolean> {
+/** conversationView is left as it is when the caller does not say. */
+export async function updateUserPreferences(
+  mailboxId: string,
+  signature: string,
+  autoSaveDrafts: boolean,
+  conversationView: boolean | null = null,
+): Promise<boolean> {
   const rows = await query<{ id: string }>(
-    `UPDATE mailboxes SET signature = $2, auto_save_drafts = $3, updated_at = NOW() WHERE id = $1 RETURNING id`,
-    [mailboxId, signature, autoSaveDrafts],
+    `UPDATE mailboxes SET signature = $2, auto_save_drafts = $3,
+            conversation_view = COALESCE($4::boolean, conversation_view), updated_at = NOW()
+      WHERE id = $1 RETURNING id`,
+    [mailboxId, signature, autoSaveDrafts, conversationView],
   );
   return rows.length === 1;
 }

services/auth/src/router.test.ts

@@ -1218,6 +1218,21 @@ describeDb("moving between the surfaces", () => {
       expect((await send("GET", "/api/v1/user/trusted-senders")).body.senders).toEqual([]);
     }, 60000);
 
+    it("lists conversations by default and remembers a switch back, without being reset by other saves", async () => {
+      const prefs = async () =>
+        (await send("GET", "/api/v1/user/preferences")).body as { conversation_view: boolean; signature: string };
+      expect((await prefs()).conversation_view).toBe(true);
+
+      await send("POST", "/api/v1/user/preferences", { signature: "x", auto_save_drafts: true, conversation_view: false });
+      expect((await prefs()).conversation_view).toBe(false);
+
+      // A save from an older screen that does not mention it must not flip it back.
+      await send("POST", "/api/v1/user/preferences", { signature: "y", auto_save_drafts: true });
+      const after = await prefs();
+      expect(after.conversation_view).toBe(false);
+      expect(after.signature).toBe("y");
+    }, 60000);
+
     it("refuses something that is not an address", async () => {
       expect((await send("PUT", "/api/v1/user/trusted-senders", { address: "not an address" })).status).toBe(400);
       expect((await send("PUT", "/api/v1/user/trusted-senders", {})).status).toBe(400);

services/auth/src/router.ts

@@ -1224,7 +1224,8 @@ async function userUpdatePreferences(req: IncomingMessage, res: ServerResponse,
   const body = await parseJsonBody(req);
   const signature = typeof body?.signature === "string" ? body.signature : "";
   const autoSaveDrafts = body?.auto_save_drafts !== false;
-  await repo.updateUserPreferences(session.sub, signature, autoSaveDrafts);
+  const conversationView = typeof body?.conversation_view === "boolean" ? body.conversation_view : null;
+  await repo.updateUserPreferences(session.sub, signature, autoSaveDrafts, conversationView);
   sendJson(res, 200, { ok: true });
 }