diff --git a/src/wwgpt/ww.py b/src/wwgpt/ww.py
index 95418d7..d1e1098 100644
--- a/src/wwgpt/ww.py
+++ b/src/wwgpt/ww.py
@@ -708,6 +708,13 @@ def apply_external_wwpgd(
                 "combined_hardness_requested": req_h, "combined_hardness_applied": req_h * scale, "trust_region_limit": limit, "trust_region_scale": scale,
                 "relative_frobenius_change_requested": req_rel, "relative_frobenius_change_applied": app_rel, "relative_frobenius_change": app_rel,
                 "relative_frobenius_weight_change": app_rel, "changed": changed, "projection_attempted": req_h > 0.0, "projected": changed})
+            # Dose identity for cross-run / cross-actuator comparison (logging only).
+            # Definition: Frobenius ||W_after - W_before|| / ||W_before|| of the applied update.
+            rows[-1].update({
+                "dose_definition": "relative_frobenius_change_applied",
+                "dose_relative_frobenius": app_rel,
+                "is_first_projection_event": int(event_index) == 1,
+            })
             rows[-1].update({"displacement_kind": displacement_kind,
                              "real_candidate_displacement_cosine": displacement_cosine,
                              "sham_seed": int(sham_seed) if sham_seed is not None else None})
diff --git a/tests/test_external_wwpgd_pass3.py b/tests/test_external_wwpgd_pass3.py
index 176bb46..92f8bd7 100644
--- a/tests/test_external_wwpgd_pass3.py
+++ b/tests/test_external_wwpgd_pass3.py
@@ -106,6 +106,19 @@ def test_no_strength_multiplier_external_blend_eta(monkeypatch):
     assert all(row["blend_eta"] == 0.5 for row in rows)
 
 
+def test_projection_rows_include_dose_identity_fields(monkeypatch):
+    """Every projection row names the dose metric used for strength comparison."""
+    install_fake_ww_pgd(monkeypatch, [])
+    rows = apply_external_wwpgd(tiny_model(), actual_step=1, event_index=1)
+    assert rows
+    for row in rows:
+        assert row["dose_definition"] == "relative_frobenius_change_applied"
+        assert row["dose_relative_frobenius"] == row["relative_frobenius_change_applied"]
+        assert row["is_first_projection_event"] is True
+    rows2 = apply_external_wwpgd(tiny_model(), actual_step=2, event_index=2)
+    assert all(row["is_first_projection_event"] is False for row in rows2)
+
+
 def test_projection_interval_accepts_positive_integers():
     ext = WWPGDExtension(cfg=WWPGDConfig(), interval=3)
     assert ext.interval == 3