fix(handoff): resolve database by connection host, not name alone

src/provably/handoff/_bootstrap.py

@@ -94,7 +94,7 @@ def _onboard_database(current_org: str, middleware_id: str, postgres_url: str) -
         # padding step ran above to ensure provably_intercepts exists, and the backend's
         # schema introspection will pick it up so discover_intercepts_table() can find it.
         _log.info("database_already_exists_reusing")
-        database_id = resolve_existing_database_id(current_org, middleware_id, db_name)
+        database_id = resolve_existing_database_id(current_org, middleware_id, db_name, body["uri"])
         if not database_id:
             log_failed_response(resp)
             raise RuntimeError("Database exists but could not resolve existing database_id")

src/provably/handoff/_discovery.py

@@ -27,7 +27,8 @@ def discover_intercepts_table(org_id: str, middleware_id: str, database_id: str)
     return _node_to_bundle(node)
 
 
-def resolve_existing_database_id(org_id: str, middleware_id: str, db_name: str) -> str:
+def resolve_existing_database_id(org_id: str, middleware_id: str, db_name: str, host: str = "") -> str:
+    candidates: list[str] = []
     for path in (
         f"/api/v1/organizations/{org_id}/middlewares/{middleware_id}/databases",
         f"/api/v1/organizations/{org_id}/databases",
@@ -43,15 +44,34 @@ def resolve_existing_database_id(org_id: str, middleware_id: str, db_name: str)
                     db_id = extract_id(item, ["id", "database_id"])
                 except ValueError:
                     continue
-                if db_id:
-                    return db_id
+                if db_id and db_id not in candidates:
+                    candidates.append(db_id)
+    # Same name can map to several registrations on different hosts; pick the one whose
+    # stored host matches `host` so we don't bind to a different physical DB.
+    if host:
+        matched = [db_id for db_id in candidates if _database_host(org_id, middleware_id, db_id) == host]
+        if matched:
+            return matched[0]
+        if len(candidates) > 1:
+            return ""  # ambiguous and none matched the host — refuse to guess
+    if candidates:
+        return candidates[0]
     try:
         data = get_json(f"/api/v1/organizations/{org_id}/data")
         return find_first_id(data, ("database_id",))
     except Exception:  # noqa: BLE001
         return ""
 
 
+def _database_host(org_id: str, middleware_id: str, database_id: str) -> str:
+    """Stored connection host for a database (the list endpoint omits it; the detail one has it)."""
+    try:
+        detail = get_json(f"/api/v1/organizations/{org_id}/middlewares/{middleware_id}/databases/{database_id}")
+    except Exception:  # noqa: BLE001
+        return ""
+    return str(detail.get("uri") or "").strip()
+
+
 def resolve_existing_collection_id(org_id: str, middleware_id: str, database_id: str, table_id: str) -> str:
     try:
         payload = get_json(f"/api/v1/organizations/{org_id}/collections")