CaloReco: support PhotonClusterBuilder BDT loading from CDB

offline/packages/CaloReco/PhotonClusterBuilder.cc

@@ -26,6 +26,8 @@
 
 #include <fun4all/Fun4AllReturnCodes.h>
 
+#include <ffamodules/CDBInterface.h>
+
 #include <TMVA/RBDT.hxx>
 
 #include <algorithm>
@@ -64,7 +66,44 @@ int PhotonClusterBuilder::InitRun(PHCompositeNode* topNode)
   // BDT
   if (m_do_bdt)
   {
-    m_bdt = std::make_unique<TMVA::Experimental::RBDT>("myBDT", m_bdt_model_file);
+    m_bdt.reset();
+    if (m_bdt_feature_list.empty())
+    {
+      std::cerr << Name() << ": BDT enabled without an ordered feature list" << std::endl;
+      return Fun4AllReturnCodes::ABORTRUN;
+    }
+
+    std::string model_file = m_bdt_model_file;
+    if (!m_bdt_model_cdb_domain.empty())
+    {
+      model_file = CDBInterface::instance()->getUrl(m_bdt_model_cdb_domain);
+      if (model_file.empty())
+      {
+        std::cerr << Name() << ": no BDT model found for CDB domain '"
+                  << m_bdt_model_cdb_domain << "'" << std::endl;
+        return Fun4AllReturnCodes::ABORTRUN;
+      }
+    }
+
+    if (model_file.empty())
+    {
+      std::cerr << Name() << ": BDT model filename is empty" << std::endl;
+      return Fun4AllReturnCodes::ABORTRUN;
+    }
+    try
+    {
+      m_bdt = std::make_unique<TMVA::Experimental::RBDT>("myBDT", model_file);
+    }
+    catch (const std::exception& error)
+    {
+      std::cerr << Name() << ": could not load BDT model '" << model_file
+                << "': " << error.what() << std::endl;
+      return Fun4AllReturnCodes::ABORTRUN;
+    }
+    if (Verbosity() > 0)
+    {
+      std::cout << Name() << ": BDT model: " << model_file << std::endl;
+    }
   }
 
   // locate input raw cluster container

offline/packages/CaloReco/PhotonClusterBuilder.h

@@ -38,7 +38,15 @@ class PhotonClusterBuilder : public SubsysReco
   void set_output_photon_node(const std::string& n) { m_output_photon_node = n; }
   void set_ET_threshold(float e) { m_min_cluster_et = e; }
   void set_shower_shape_min_tower_energy(float e) { m_shape_min_tower_E = e; }
-  void set_bdt_model_file(const std::string& path) { m_bdt_model_file = path; }
+  // Select a local model file, overriding any previously selected CDB domain.
+  void set_bdt_model_file(const std::string& path)
+  {
+    m_bdt_model_file = path;
+    m_bdt_model_cdb_domain.clear();
+  }
+  // Select CDB loading with the job's existing global tag and timestamp.
+  // An empty domain restores file-based loading; no file fallback is used in CDB mode.
+  void set_bdt_model_cdb_domain(const std::string& domain) { m_bdt_model_cdb_domain = domain; }
   void set_bdt_feature_list(const std::vector<std::string>& features) { m_bdt_feature_list = features; }
   void set_do_bdt(bool do_bdt) { m_do_bdt = do_bdt; }
   void set_do_subtracted_iso(bool do_subtracted_iso) { m_do_subtracted_iso = do_subtracted_iso; }
@@ -66,6 +74,7 @@ class PhotonClusterBuilder : public SubsysReco
   float m_min_cluster_et{5.0f};
   float m_shape_min_tower_E{0.070f};
   std::string m_bdt_model_file{"myBDT_5.root"};
+  std::string m_bdt_model_cdb_domain;
   std::vector<std::string> m_bdt_feature_list;
   float m_vertex{std::numeric_limits<float>::quiet_NaN()};
   float m_subtracted_iso_defval{-999};

offline/packages/CaloReco/README.PhotonClusterBuilder.md

@@ -0,0 +1,81 @@
+# PhotonClusterBuilder BDT loading
+
+BDT scoring is optional and disabled by default. When enabled, the builder
+loads a TMVA `RBDT` named `myBDT` during `InitRun` and stores the score as the
+`bdt_score` shower-shape parameter. The caller supplies the ordered features
+expected by the model.
+
+## Load a model from CDB
+
+Set `set_bdt_model_cdb_domain(...)` before registering the builder. The lookup
+uses the standard `CDBInterface` and the job's existing `CDB_GLOBALTAG` and
+`TIMESTAMP`. The builder does not set or change either flag.
+
+For the PPG12 baseV3E photon-ID model, configure the builder as follows in a
+Fun4All macro after the input clusters, calibrated towers and geometry have
+been configured:
+
+```cpp
+#include <TMVA/RBDT.hxx>
+#include <caloreco/PhotonClusterBuilder.h>
+#include <fun4all/Fun4AllServer.h>
+
+R__LOAD_LIBRARY(libcalo_reco.so)
+
+auto* photons = new PhotonClusterBuilder();
+photons->set_do_bdt(true);
+photons->set_bdt_model_cdb_domain("PPG12_PHOTON_ID_BDT");
+photons->set_bdt_feature_list({
+    "cluster_Et", "cluster_weta_cogx", "cluster_wphi_cogx",
+    "vertexz", "cluster_Eta", "e11_over_e33",
+    "cluster_et1", "cluster_et2", "cluster_et3", "cluster_et4",
+    "e32_over_e35"});
+photons->Verbosity(1);  // Print the resolved model filename.
+Fun4AllServer::instance()->registerSubsystem(photons);
+```
+
+The published baseV3E payload is available for these settings:
+
+| Sample | `CDB_GLOBALTAG` | `TIMESTAMP` |
+| --- | --- | --- |
+| DATA | `newcdbtag` | Actual run number, 47289 through 53999 |
+| PPG12 MC | `MDC2` | 28 |
+
+These are job-level reconstruction settings, not an extra model-specific
+global tag. In the job's normal CDB setup, for example:
+
+```cpp
+#include <phool/recoConsts.h>
+
+auto* rc = recoConsts::instance();
+rc->set_StringFlag("CDB_GLOBALTAG", "newcdbtag");
+rc->set_uint64Flag("TIMESTAMP", 47289);  // Use the actual DATA run.
+// PPG12 MC instead uses "MDC2" and 28.
+```
+
+Keep the 11 features in exactly the order shown. Ratios with a non-positive
+denominator resolve to zero. The model is the baseV3E classifier used in the
+PPG12 `8 <= ET < 35 GeV` range; the separate `base_E` classifier outside that
+range is not selected automatically. Working-point cuts, preselection and
+photon-selection logic remain the analysis's responsibility.
+
+## Use a local file
+
+Existing file-based configurations continue to work. To override a CDB
+selection, call this after configuring the CDB domain, before `InitRun`:
+
+```cpp
+photons->set_bdt_model_file("/path/to/model_base_v3E_single_tmva.root");
+```
+
+`set_bdt_model_file` clears the CDB selection. A subsequent nonempty
+`set_bdt_model_cdb_domain` selects CDB again. Without a CDB domain, the legacy
+default filename remains `myBDT_5.root` unless explicitly changed.
+
+An empty feature list, empty resolved path, or model-loading exception aborts
+run initialization with a diagnostic. CDB mode never falls back to the local
+filename. It follows the standard `CDBInterface` behavior, including any
+enabled `_default` domain lookup or calibration-file cache; the builder does
+not change these job-wide settings. Nonempty feature lists still must match the model's
+input count, order and definitions; this interface does not infer them from
+the CDB name or change the existing feature evaluation.