merkle_sync: fix level 0 SQL range, rebuild trees at startup

- _get_level_hashes: use separate SQL without prefix64<=? for level 0.
  UINT64_MAX cast to sqlite3_int64 becomes -1, making prefix64<=-1 always
  false for positive prefixes → bitmap always 0 → sync never exchanges data.
- member_sync_init: add _rebuild_all_trees to scan all peers_* tables and
  call merkle_sync_recompute_path for each member. Ensures merkle_tree_hash
  has entries for members added before merkle sync existed.

tools/chatgui/transport/member_sync.c

@@ -306,11 +306,36 @@ static const struct merkle_sync_data_ops g_member_ops = {
 
 /* ──  Public API ── */
 
+static void _rebuild_all_trees(struct UTUN_INSTANCE* inst) {
+    sqlite3* db = _db(inst); if (!db) return;
+    sqlite3_stmt* st = NULL;
+    if (sqlite3_prepare_v2(db,
+            "SELECT name FROM sqlite_master WHERE type='table' AND name LIKE 'peers_%'",
+            -1, &st, NULL) != SQLITE_OK) return;
+    while (sqlite3_step(st) == SQLITE_ROW) {
+        const char* tbl = (const char*)sqlite3_column_text(st, 0);
+        if (!tbl || strncmp(tbl, "peers_", 6) != 0) continue;
+        const char* ch_id = tbl + 6;
+        sqlite3_stmt* ns = NULL;
+        char sql[256]; snprintf(sql, sizeof(sql), "SELECT node_id FROM \"%s\"", tbl);
+        if (sqlite3_prepare_v2(db, sql, -1, &ns, NULL) == SQLITE_OK) {
+            while (sqlite3_step(ns) == SQLITE_ROW) {
+                uint64_t nid = (uint64_t)sqlite3_column_int64(ns, 0);
+                merkle_sync_recompute_path(inst, ch_id, nid);
+                DEBUG_DEBUG(DEBUG_CATEGORY_DB_SYNC, "%s: rebuild tree ns=%s nid=%016llx", MS_ID, ch_id, (unsigned long long)nid);
+            }
+            sqlite3_finalize(ns);
+        }
+    }
+    sqlite3_finalize(st);
+}
+
 int member_sync_init(struct UTUN_INSTANCE* inst) {
     if (!inst) return -1;
     DEBUG_TRACE(DEBUG_CATEGORY_DB_SYNC, "%s: init", MS_ID);
     int rc = merkle_sync_init(inst, 0x31, &g_member_ops, inst);
     if (rc != 0) return rc;
+    _rebuild_all_trees(inst);
     DEBUG_INFO(DEBUG_CATEGORY_DB_SYNC, "%s: initialized, merkle_rc=%d", MS_ID, rc);
     return 0;
 }

tools/chatgui/transport/merkle_sync.c

@@ -173,22 +173,25 @@ static int _get_level_hashes(struct merkle_sync* ms, const char* ns,
         next_shift = 63 - ((int)level + 1) * 5; if (next_shift < 0) next_shift = 0;
     }
 
-    uint64_t range_end = (level == 0) ? UINT64_MAX
-        : prefix | (0x1FULL << (next_shift > 0 ? next_shift : 0));
-
     sqlite3_stmt* stmt = NULL;
     int query_level = (int)(level + 1);
-    if (sqlite3_prepare_v2(db,
-            "SELECT prefix64, hash FROM merkle_tree_hash"
-            " WHERE namespace=? AND level=? AND prefix64>=? AND prefix64<=?"
-            " ORDER BY prefix64", -1, &stmt, NULL) != SQLITE_OK || !stmt) {
+    const char* sql = (level == 0)
+        ? "SELECT prefix64, hash FROM merkle_tree_hash"
+          " WHERE namespace=? AND level=? ORDER BY prefix64"
+        : "SELECT prefix64, hash FROM merkle_tree_hash"
+          " WHERE namespace=? AND level=? AND prefix64>=? AND prefix64<=?"
+          " ORDER BY prefix64";
+    if (sqlite3_prepare_v2(db, sql, -1, &stmt, NULL) != SQLITE_OK || !stmt) {
         DEBUG_ERROR(DEBUG_CATEGORY_DB_SYNC, "%s: _get_level_hashes SQL error ns=%s L%d — %s", MS_ID, ns, level, sqlite3_errmsg(db));
         return -1;
     }
     sqlite3_bind_text(stmt, 1, ns, -1, SQLITE_STATIC);
     sqlite3_bind_int(stmt, 2, query_level);
-    sqlite3_bind_int64(stmt, 3, (sqlite3_int64)prefix);
-    sqlite3_bind_int64(stmt, 4, (sqlite3_int64)range_end);
+    if (level > 0) {
+        uint64_t range_end = prefix | (0x1FULL << (next_shift > 0 ? next_shift : 0));
+        sqlite3_bind_int64(stmt, 3, (sqlite3_int64)prefix);
+        sqlite3_bind_int64(stmt, 4, (sqlite3_int64)range_end);
+    }
     while (sqlite3_step(stmt) == SQLITE_ROW) {
         sqlite3_int64 row_pfx = sqlite3_column_int64(stmt, 0);
         const void* h = sqlite3_column_blob(stmt, 1);