perf(inbox): read message bodies only for pages that include them

CHANGELOG.md

@@ -7,6 +7,10 @@ Notable changes to Swarmail. Versions follow [semantic versioning](https://semve
 - `swarmail who` asks git about each running T3 thread directory once instead of once per thread. With about 800
   running threads in 149 directories it took 0.3 s instead of 1.6 s.
 
+- `fetch_inbox` and `fetch_session_inbox` no longer read each message body from storage when `include_bodies` is off,
+  which is the default. A page of 20 messages took 48 µs instead of 57 µs with 2 KB bodies and 52 µs instead of 82 µs
+  with 17 KB bodies.
+
 ## 0.5.2 - 2026-10-09
 
 - Require agents to record whole-session closeouts and retire their own project

src/store.ts

@@ -678,12 +678,17 @@ export class MailStore {
     };
   }
 
+  /** Bodies are the one large column; read them only for a page that includes them. */
+  private bodyColumn(a: Args): string {
+    return a.include_bodies ? "m.body_md" : "NULL AS body_md";
+  }
+
   inbox(p: Project, who: Agent, a: Args, markRead: boolean) {
     const now = nowUs();
     const rows = this.db
       .query<Row, any[]>(
         `SELECT m.id, m.project_id, m.sender_id, m.thread_id, m.topic, m.subject, m.importance, m.notification_policy, m.revision, m.ack_required,
-              s.name AS "from", m.sender_location, m.created_ts, r.read_ts, r.ack_ts, r.kind, m.body_md
+              s.name AS "from", m.sender_location, m.created_ts, r.read_ts, r.ack_ts, r.kind, ${this.bodyColumn(a)}
        FROM message_recipients r JOIN messages m ON m.id = r.message_id JOIN agents s ON s.id = m.sender_id
        WHERE r.agent_id = ?1 AND r.withdrawn_ts IS NULL AND (?2 = 0 OR r.read_ts IS NULL) AND (?3 = 0 OR m.importance IN ('high', 'urgent'))
          AND r.created_ts > ?4 AND (?5 IS NULL OR m.topic = ?5)
@@ -729,7 +734,7 @@ export class MailStore {
     const rows = this.db
       .query<Row, any[]>(`
       SELECT m.id, m.thread_id, m.subject, m.importance, m.notification_policy, m.revision,
-             m.ack_required, m.created_ts, m.body_md, s.name AS "from",
+             m.ack_required, m.created_ts, ${this.bodyColumn(a)}, s.name AS "from",
              r.read_ts, r.ack_ts, a.id AS recipient_id, a.name AS agent_name,
              p.human_key AS project_key
       FROM agents a JOIN projects p ON p.id = a.project_id