refactor: remove stale detector schema keys and single-mode duplicates

- DEFAULT_JSON_SCHEMA: drop the 8 detector_* keys left over from the
  removed detector_response module; CLI dry-run drops the dead
  'Detector: not configured (Phase 4)' line
- CSV export: single-mode no longer writes branch_1_PhaseSpace /
  branch_1_Radiative duplicates next to the bare PhaseSpace/Radiative
  columns; per-branch core factors only in multi-branch mode
- Visualizer: debug panels fall back to the unprefixed core-factor
  columns for single-mode CSVs instead of skipping them
- Spectrum ylabel now states the actual units: normalized spectrum
  [MeV^-1], not 'Normalized Counts / keV'
- tests: defaults assert detector keys gone; column layout pinned for
  single vs multi; panel and ylabel assertions

beta_spectrum/cli.py

@@ -372,8 +372,6 @@ def _print_dry_run_output(config, source_type: str) -> None:
     else:
         print("Mode: single-branch")
 
-    # Detector response is a Phase 4 feature — not yet implemented
-    print("Detector:   not configured (Phase 4)")
     print("========================================")
 
 

beta_spectrum/nuclear_data.py

@@ -554,14 +554,6 @@ DEFAULT_JSON_SCHEMA = {
     "transition_type": "F2",
     "e_step_MeV": 0.001,
     "neutrino_mass_MeV": 0.0,
-    "detector_model": "gaussian",
-    "detector_sigma_a_keV": 1.0,
-    "detector_sigma_b": 0.0,
-    "detector_tail_fraction": 0.0,
-    "detector_tau_keV": 5.0,
-    "detector_fano_factor": 0.12,
-    "detector_n_channels": 4096,
-    "detector_channel_energy_range": [0.0, 0.35],
 }
 
 

beta_spectrum/output/csv_export.py

@@ -211,14 +211,20 @@ class CSVEmitter:
 
         if csv_verbosity == "full":
             # Per-branch component columns (factorized ingredients).
-            for i in range(n_branches):
-                for comp_name in ["PhaseSpace", "Radiative"]:
-                    key = analyzer._get_component_key(i, comp_name)
-                    if key in components:
-                        data[f"branch_{i + 1}_{comp_name}"] = components[key]
+            # Only multi-branch mode carries per-branch factors: in single
+            # mode the bare PhaseSpace/Radiative columns below already
+            # describe the single spectrum, and prefixed duplicates would
+            # silently disagree with them once renamed.
+            if analyzer._is_multi:
+                for i in range(n_branches):
+                    for comp_name in ["PhaseSpace", "Radiative"]:
+                        key = analyzer._get_component_key(i, comp_name)
+                        if key in components:
+                            data[f"branch_{i + 1}_{comp_name}"] = components[key]
 
             # Universal components (no prefix): Fermi plus universal
-            # higher-order corrections.
+            # higher-order corrections. In single mode the core factors
+            # (PhaseSpace, Radiative) also appear here unprefixed.
             for name, values in components.items():
                 if not name.startswith("branch_"):
                     data[name] = values

beta_spectrum/output/visualization.py

@@ -235,7 +235,6 @@ def _plot_spectra_view_from_df(
 ) -> Figure:
     """Plot total spectrum and per-branch spectra from CSV columns."""
     energies = df["energy_MeV"].to_numpy()
-    e_step_keV = (meta["e_step_MeV"] or 0.0) * 1000.0
 
     fig, ax = plt.subplots(figsize=(12, 7))
 
@@ -266,7 +265,7 @@ def _plot_spectra_view_from_df(
         )
 
     ax.set_xlabel(r"Electron kinetic energy $E$ [MeV]", fontsize=12)
-    ax.set_ylabel(f"Normalized Counts / {e_step_keV:.1f} keV", fontsize=12)
+    ax.set_ylabel(r"Normalized spectrum [MeV$^{-1}$]", fontsize=12)
     fig.suptitle(_spectrum_title(meta), fontsize=14, fontweight="bold")
     ax.set_yscale("log")
     ax.grid(True, alpha=0.3)
@@ -288,7 +287,6 @@ def _plot_debug_view_from_df(
 ) -> Figure:
     """Debug view (4 panels) built entirely from CSV columns."""
     energies = df["energy_MeV"].to_numpy()
-    e_step_keV = (meta["e_step_MeV"] or 0.0) * 1000.0
     active = _active_branches(meta)
 
     fig, axes = plt.subplots(4, 1, figsize=(12, 16), sharex=True)
@@ -318,7 +316,7 @@ def _plot_debug_view_from_df(
             label=f"Br. {b['index']} ({b['intensity'] * 100:.1f}%)",
         )
     ax.set_yscale("log")
-    ax.set_ylabel(f"Normalized Counts / {e_step_keV:.1f} keV", fontsize=10)
+    ax.set_ylabel(r"Normalized spectrum [MeV$^{-1}$]", fontsize=10)
     ax.set_title("Spectrum", fontsize=11)
     ax.grid(True, alpha=0.3)
     ax.legend(fontsize=8, loc="best", ncol=2)
@@ -331,6 +329,9 @@ def _plot_debug_view_from_df(
         ax.plot(energies, fermi_scaled, "r-", lw=1.5, label="Fermi", alpha=0.8)
     for color_i, b in enumerate(active):
         col = f"branch_{b['index']}_PhaseSpace"
+        if col not in df.columns:
+            # Single-branch CSVs carry the core factors unprefixed.
+            col = "PhaseSpace"
         if col not in df.columns:
             continue
         ps_vals = df[col].to_numpy()
@@ -374,6 +375,9 @@ def _plot_debug_view_from_df(
     ax = axes[3]
     for color_i, b in enumerate(active):
         col = f"branch_{b['index']}_Radiative"
+        if col not in df.columns:
+            # Single-branch CSVs carry the core factors unprefixed.
+            col = "Radiative"
         if col not in df.columns:
             continue
         ax.plot(