Chat: expose typed room attachment references (#477)

ddiff --git a/server/rooms/files.js b/server/rooms/files.js
iindex 3baed65..bc5ae40 100644
---- a/server/rooms/files.js
++++ b/server/rooms/files.js
@@@ -61,4 +61,18 @@ function filesOf(message) {
      return Array.isArray(files) ? files : [];
  }
  
--module.exports = { cleanFiles, filesOf, attachmentsFromBody, MAX_FILES };
++/** Public message attachment refs, projected from owner-validated Media ids. */
++function attachmentRefs(files) {
++    const origin = require('../config').media.publicOrigin;
++    return (Array.isArray(files) ? files : []).map((file) => {
++        const type = String(file.media_type || 'application/octet-stream');
++        const kind = type.startsWith('image/') ? 'picture' : type.startsWith('video/') ? 'video' : type.startsWith('audio/') ? 'audio' : 'file';
++        return {
++            kind, service: 'media', id: file.id,
++            url: `${origin}/o/${encodeURIComponent(file.id)}`,
++            name: file.name || 'file', size: Number(file.size) || 0, type,
++        };
++    });
++}
++
++module.exports = { cleanFiles, filesOf, attachmentRefs, attachmentsFromBody, MAX_FILES };
ddiff --git a/server/rooms/rooms.js b/server/rooms/rooms.js
iindex 928df54..777e755 100644
---- a/server/rooms/rooms.js
++++ b/server/rooms/rooms.js
@@@ -362,7 +362,10 @@ const MSG_SELECT = `SELECT m.id, m.room_id, m.user_id, m.message, m.card, m.file
      LEFT JOIN room_ai_members a ON a.id = m.ai_member_id`;
  async function messageById(id) {
      const row = await db.get(`${MSG_SELECT} WHERE m.id = ?`, [id]) || null;
--    if (row) await linkCards.hydrate([row], 'room_messages');
++    if (row) {
++        row.attachments = messageFiles.attachmentRefs(messageFiles.filesOf(row));
++        await linkCards.hydrate([row], 'room_messages');
++    }
      return row;
  }
  
@@@ -374,6 +377,7 @@ async function history(room, { before = null, after = null, limit = 60 } = {}) {
          : before != null
              ? await db.all(`${MSG_SELECT} WHERE m.room_id = ? AND m.id < ? AND m.is_deleted = 0 ORDER BY m.id DESC LIMIT ?`, [room.id, Number(before) || 0, lim])
              : await db.all(`${MSG_SELECT} WHERE m.room_id = ? AND m.is_deleted = 0 ORDER BY m.id DESC LIMIT ?`, [room.id, lim]);
++    for (const row of rows) row.attachments = messageFiles.attachmentRefs(messageFiles.filesOf(row));
      await linkCards.hydrate(rows, 'room_messages');
      return after != null ? rows : rows.reverse();
  }
ddiff --git a/test/room-attachments.test.js b/test/room-attachments.test.js
iindex ad6010e..461e285 100644
---- a/test/room-attachments.test.js
++++ b/test/room-attachments.test.js
@@@ -9,6 +9,10 @@ t('room message attachments accept the public field name and enforce the ten-fil
      assert.deepEqual(files.attachmentsFromBody({ files: [{ id: 'b' }] }), [{ id: 'b' }]);
      assert.deepEqual(files.attachmentsFromBody({ attachments: 'invalid', files: [{ id: 'b' }] }), [{ id: 'b' }]);
      assert.throws(() => files.cleanFiles(Array(11).fill({ id: 'med_01ARZ3NDEKTSV4RRFFQ69G5FAV' })), (err) => err.code === 'rooms.files_too_many' && err.status === 413);
++    assert.deepEqual(files.attachmentRefs([{ id: 'med_01ARZ3NDEKTSV4RRFFQ69G5FAV', name: 'scan.pdf', size: 12, media_type: 'application/pdf' }]), [{
++        kind: 'file', service: 'media', id: 'med_01ARZ3NDEKTSV4RRFFQ69G5FAV', url: 'https://openvibe.media/o/med_01ARZ3NDEKTSV4RRFFQ69G5FAV',
++        name: 'scan.pdf', size: 12, type: 'application/pdf',
++    }]);
  });
  
  t.run();