Phase 13.42.DF FIX2: close 5 items deferred at FIX1.

B6:    suptitle padding adapts to title line count (per v1.2 §4)
B7:    faceted+fit no-crash smoke verify (per v1.2 §4, cascade from B2)
I-8:   hist + weights + fit emits UserWarning (per v1.2 §8 B5(c) commitment)
ADV-1: stacked + selection_vector(>1) + fit raises NotImplementedError
       (per v1.2 §8 D9(d) commitment)
ADV-3: fit_textbox_kwargs in 3 FORWARDED_NAMES tuples + outer DFDraw
       signatures + explicit forwarding sites (per Sonnet55 v1.2 P2-2;
       also satisfies Phase 13.43 v1.2 §9 carry-forward checklist)

Closes the items wrongly deferred at FIX1. See companion governance
memo Claude48_Feedback_FIX1_Defer_Anti_Pattern_20260527.md for the
process gap analysis and proposed QRC AliceO2Group#11 + Reviewer supplement.

Tests: 6 new (F.59, F.60, F.61, F.61b, F.62, F.63) in
TestPhase1342FIX2Regressions. Taxonomy staged in-commit (FIT.inlTestPhase1342FIX2Regressions. Taxonomy staged in-commit (F0 / 1.

Author: miranov25

UTILS/dfextensions/dfdraw/docs/CAPABILITY_MATRIX.md

@@ -1,6 +1,6 @@
 # Capability Matrix — dfdraw
 
-**Generated:** 2026-05-27 06:53 UTC
+**Generated:** 2026-05-27 11:43 UTC
 **Phase:** 13.15.DF
 **Generator:** `scripts/generate_capability_matrix.py`
 **Sources:** `tests/feature_taxonomy.py` + `tests/test_layer_classification.py`
@@ -14,8 +14,8 @@
 | 🧨 Broken | 0 | 0% |
 | 📋 Planned | 1 | 1% |
 | **Total features** | **108** | |
-| **Total proof tests** | **536** | |
-| **Invariance tests** | **307** | |
+| **Total proof tests** | **542** | |
+| **Invariance tests** | **313** | |
 
 **Status key:**
 - ✅ Verified — has at least one invariance test (A ≡ B check)
@@ -172,7 +172,7 @@
 | | **FACET** | | |
 | ✅ | **FACET.list_grid** — facet_by accepts Union[str, List[str]] for 1D/2D/3D faceting. Convention LOCKED matching numpy/pandas (n_rows, n_cols, ...) shape: facet_by[0]=ROW (vertical within figure), facet_by[1]=COLUMN (horizontal within figure), facet_by[2]=FIGID (separate figures, one per value). facet_by[3+] raises NotImplementedError. 3D returns (List[Figure], List[axes_2d], List[stats_dict]) — DEVIATES from standard (fig, ax, stats) contract; documented prominently in inline help. New params: share_x/share_y ∈ {'all','row','col','none'} (within-figure axis sharing), share_across_figures: bool (3D global range lock). Per-plot-kind lock for share_across_figures (CP1-2): scatter locks x AND y; hist/profile locks x only (y auto-scales per figure to handle sparse-figID variance). New helpers: _normalize_facet_args, _to_mpl_share (symmetric {'all':True,'row':'row','col':'col','none':False} — v1.2 CP0-1 fix for Hard Constraint #3), _validate_share_axis_value, _resolve_facet_values (discrete or pd.cut/qcut Interval), _filter_facet_value (CP1-3 discrete vs binned), _compute_global_ranges. dfdraw is FIRST major plotting library with unified API where Nth faceting dimension generates separate figures (seaborn/ggplot2/plotly/altair all require manual loops). _validate_facet_by_binning guard for list input (v1.3 P1-A). Per-plot-kind dispatch: hist uses range= (matplotlib convention); profile uses range= which DFDraw.profile remaps to draw_profile's x_range= internally; scatter uses ax.set_xlim/set_ylim post-draw (no native range params); hist also locks ax.set_xlim post-draw (range= only locks bins, not axis xlim). Empty cell handling: '(no data)' diagnostic + stats={'n':0,'empty':True} — Phase 13.41.DF | 23 | 0 |
 | | **FIT** | | |
-| ✅ | **FIT.inline** — Inline fits (fit= parameter on hist/profile/scatter/draw) | 35 | 0 |
+| ✅ | **FIT.inline** — Inline fits (fit= parameter on hist/profile/scatter/draw) | 41 | 0 |
 
 ---
 

UTILS/dfextensions/dfdraw/drawer.py

@@ -209,6 +209,26 @@ def _filter_facet_value(df, col, value, bins=None, quantiles=None):
     return df[mask.fillna(False) if mask.dtype == object else mask]
 
 
+def _suptitle_top_for_title(title_text):
+    """Phase 13.42.DF FIX2 (B6): compute a reasonable subplots_adjust top= value
+    based on suptitle line count, so multi-line titles or dense facet grids
+    don't overlap subplot titles.
+
+    Production-gate B6 finding (Phase 13.42 close): single-line auto_title +
+    long-facet-tuple subtitle frequently overlapped the row-0 subplot titles
+    when facet_by was 2D. The fixed top=0.92 reserved 8% for the suptitle
+    block, which is insufficient for 2-3 line titles.
+
+    Returns top fraction in [0.84, 0.94] depending on the number of newlines
+    in title_text. None → falls back to 0.92 (existing behavior).
+    """
+    if not title_text:
+        return 0.92
+    n_lines = str(title_text).count('\n') + 1
+    # 1 line → 0.93; 2 lines → 0.89; 3 lines → 0.86; 4+ → 0.84
+    return max(0.84, 0.93 - 0.035 * max(0, n_lines - 1))
+
+
 def _compute_global_ranges(df, x_expr, y_expr, plot_kind):
     """For 3D share_across_figures=True, compute global x/y ranges.
     
@@ -839,6 +859,11 @@ def _auto_label(self, y_expr, x_expr=None):
         'time_format',
         # Phase 13.42.DF: Inline fits
         'fit',
+        # Phase 13.42.DF FIX2 (ADV-3, Sonnet55 P2-2 carry-forward): per-call
+        # fit textbox formatting overrides. Pattern B (forwarded inward):
+        # draw_profile() has fit_textbox_kwargs as an explicit parameter
+        # since FIX1 and consumes it via render_fit_textbox.
+        'fit_textbox_kwargs',
     )
 
     _HIST_FORWARDED_NAMES = (
@@ -886,6 +911,9 @@ def _auto_label(self, y_expr, x_expr=None):
         'cumulative',
         # Phase 13.42.DF: Inline fits
         'fit',
+        # Phase 13.42.DF FIX2 (ADV-3, Sonnet55 P2-2 carry-forward): per-call
+        # fit textbox formatting overrides. See _PROFILE_FORWARDED_NAMES note.
+        'fit_textbox_kwargs',
     )
 
     _SCATTER_FORWARDED_NAMES = (
@@ -910,9 +938,10 @@ def _auto_label(self, y_expr, x_expr=None):
         'vector_compose', 'delta_facet',
         # Phase 13.42.DF: Inline fits
         'fit',
+        # Phase 13.42.DF FIX2 (ADV-3, Sonnet55 P2-2 carry-forward): per-call
+        # fit textbox formatting overrides. See _PROFILE_FORWARDED_NAMES note.
+        'fit_textbox_kwargs',
     )
-
-    # Phase 13.32.DF Sub-fix 3: hist2d gets its own FORWARDED_NAMES tuple
     # (previously absent — hist2d used inline kwargs handling).
     _HIST2D_FORWARDED_NAMES = (
         'selection', 'sample', 'bins', 'range', 'norm', 'stats',
@@ -2108,7 +2137,7 @@ def _dispatch_normalize_render(
                         f"{_main}\n{_sub}" if _sub else _main,
                         fontsize=get_style_value("axes.titlesize", 14),
                     )
-                    plt.subplots_adjust(top=0.92)
+                    plt.subplots_adjust(top=_suptitle_top_for_title(fig._suptitle.get_text() if getattr(fig, '_suptitle', None) else None))
             except Exception:
                 # Failsafe — same defensive pattern as BUG-002 fix.
                 _y_str = (y_list if isinstance(y_list, str)
@@ -2117,7 +2146,7 @@ def _dispatch_normalize_render(
                           else str(x_list[0] if x_list else ''))
                 fig.suptitle(f"{_y_str} vs {_x_str}",
                              fontsize=get_style_value("axes.titlesize", 14))
-                plt.subplots_adjust(top=0.92)
+                plt.subplots_adjust(top=_suptitle_top_for_title(fig._suptitle.get_text() if getattr(fig, '_suptitle', None) else None))
 
         # --- 9. Build stats dict (M1 scope per v1.1 §7) ------------------------
         # Drop profile_data from user-facing stats — internal-only.
@@ -2451,15 +2480,15 @@ def _dispatch_normalize_grouped_render(
                         f"{_main}\n{_sub}" if _sub else _main,
                         fontsize=get_style_value("axes.titlesize", 14),
                     )
-                    plt.subplots_adjust(top=0.92)
+                    plt.subplots_adjust(top=_suptitle_top_for_title(fig._suptitle.get_text() if getattr(fig, '_suptitle', None) else None))
             except Exception:
                 _y_str = (y_list if isinstance(y_list, str)
                           else f"[{','.join(map(str, y_list))}]")
                 _x_str = (x_list if isinstance(x_list, str)
                           else str(x_list[0] if x_list else ''))
                 fig.suptitle(f"{_y_str} vs {_x_str}",
                              fontsize=get_style_value("axes.titlesize", 14))
-                plt.subplots_adjust(top=0.92)
+                plt.subplots_adjust(top=_suptitle_top_for_title(fig._suptitle.get_text() if getattr(fig, '_suptitle', None) else None))
 
         # --- 11. Build stats dict (M2 grouped contract) -----------------------
         stats_dict: Dict[str, Any] = {
@@ -2757,15 +2786,15 @@ def _dispatch_normalize_faceted_render(
                         f"{_main}\n{_sub}" if _sub else _main,
                         fontsize=get_style_value("axes.titlesize", 14),
                     )
-                    plt.subplots_adjust(top=0.92)
+                    plt.subplots_adjust(top=_suptitle_top_for_title(fig._suptitle.get_text() if getattr(fig, '_suptitle', None) else None))
             except Exception:
                 _y_str = (y_list if isinstance(y_list, str)
                           else f"[{','.join(map(str, y_list))}]")
                 _x_str = (x_list if isinstance(x_list, str)
                           else str(x_list[0] if x_list else ''))
                 fig.suptitle(f"{_y_str} vs {_x_str}",
                              fontsize=get_style_value("axes.titlesize", 14))
-                plt.subplots_adjust(top=0.92)
+                plt.subplots_adjust(top=_suptitle_top_for_title(fig._suptitle.get_text() if getattr(fig, '_suptitle', None) else None))
 
         # --- 8. Stats dict ----------------------------------------------------
         stats_dict: Dict[str, Any] = {
@@ -3352,7 +3381,7 @@ def _dispatch_faceted_render(
                         f"{_main}\n{_sub}" if _sub else _main,
                         fontsize=get_style_value("axes.titlesize", 14),
                     )
-                    plt.subplots_adjust(top=0.92)
+                    plt.subplots_adjust(top=_suptitle_top_for_title(fig._suptitle.get_text() if getattr(fig, '_suptitle', None) else None))
             except Exception:
                 # Failsafe: minimal title — prevents auto_title import/build
                 # errors from crashing the plot. Same defensive pattern as
@@ -3361,11 +3390,11 @@ def _dispatch_faceted_render(
                          else f"[{','.join(y_expr)}]")
                 fig.suptitle(f"{y_str} vs {x_expr}",
                              fontsize=get_style_value("axes.titlesize", 14))
-                plt.subplots_adjust(top=0.92)
+                plt.subplots_adjust(top=_suptitle_top_for_title(fig._suptitle.get_text() if getattr(fig, '_suptitle', None) else None))
 
         plt.tight_layout()
         if title:
-            plt.subplots_adjust(top=0.92)
+            plt.subplots_adjust(top=_suptitle_top_for_title(fig._suptitle.get_text() if getattr(fig, '_suptitle', None) else None))
 
         # ---- Combined stats ------------------------------------------------
         combined_stats = {
@@ -3682,6 +3711,11 @@ def draw(
         normalize_layout: str = "overlay+diff",
         # Phase 13.42.DF: Inline fit specification (architect 2026-05-22).
         fit: Optional[Union[str, Dict, Callable, List]] = None,
+        # Phase 13.42.DF FIX2 (ADV-3, Sonnet55 P2-2 carry-forward):
+        # per-call fit textbox formatting overrides. Pattern B —
+        # forwarded inward; consumed by inner draw_hist/profile/scatter
+        # via render_fit_textbox.
+        fit_textbox_kwargs: Optional[Dict] = None,
         **kwargs
     ) -> DrawResult:
         """
@@ -3950,6 +3984,11 @@ def hist(
         linestyle_cycle: bool = False,
         # Phase 13.42.DF: Inline fit specification
         fit: Optional[Union[str, Dict, Callable, List]] = None,
+        # Phase 13.42.DF FIX2 (ADV-3, Sonnet55 P2-2 carry-forward):
+        # per-call fit textbox formatting overrides. Pattern B —
+        # forwarded inward; consumed by inner draw_hist/profile/scatter
+        # via render_fit_textbox.
+        fit_textbox_kwargs: Optional[Dict] = None,
         **kwargs
     ) -> DrawResult:
         """
@@ -4006,6 +4045,37 @@ def hist(
         # Parse expression (take first part only for 1D)
         y_expr, x_expr = self._parse_expr(expr)
 
+        # Phase 13.42.DF FIX2 (ADV-1, Sonnet55 v1.2 panel finding, v1.2 §8
+        # D9(d) commitment): stacked=True + selection_vector (>1 selection)
+        # + fit= has ambiguous semantics in the current architecture (does
+        # each selection get its own stack? overlay without sum? fit per
+        # selection or per-stack-component or on the stacked total?).
+        # Architect did not ratify any of these in v1.2. Until a concrete
+        # use case drives the design, raise NotImplementedError with a clear
+        # actionable suggestion so users don't get silently wrong output.
+        # Placed BEFORE vector dispatch so the 3-axis-inner length-equality
+        # validator inside _compute_vector_iteration_indices does not pre-empt
+        # this more-specific architectural error.
+        # Note: `stacked` is forwarded via **kwargs on DFDraw.hist (not a
+        # named outer param), so we read it from kwargs.
+        if (kwargs.get('stacked') is True
+                and selection_vector is not None and len(selection_vector) > 1
+                and fit is not None):
+            raise NotImplementedError(
+                "Phase 13.42.DF FIX2 (ADV-1): the combination "
+                "stacked=True + selection_vector (>1 selection) + fit= is not "
+                "supported. Selection-vector semantics for stacked-hist fits "
+                "were not ratified in Phase 13.42 (v1.2 §8 D9(d) — coder did "
+                "not specify which of {per-selection fit, per-stack-component "
+                "fit, fit on the stacked total} applies). "
+                "Fix options: "
+                "(a) drop stacked=True (per-group fits work via D9/R4); or "
+                "(b) loop over selections in user code with separate hist() "
+                "calls; or "
+                "(c) drop fit= and use Phase 13.43 summary_fit= when "
+                "available."
+            )
+
         # Phase 13.16.DF: Vector dispatch
         # Phase 13.16.DF FIX1: tuple-driven forwarding via _HIST_FORWARDED_NAMES
         # + R4 fail-fast guard on facet=True + vector.
@@ -4154,6 +4224,9 @@ def hist(
                 cumulative=cumulative,
                 # Phase 13.42.DF: inline fits — recursive forwarding through facet
                 fit=fit,
+                # Phase 13.42.DF FIX2 (ADV-3): fit_textbox_kwargs paired
+                # with fit= (R6 validator now requires explicit forwarding).
+                fit_textbox_kwargs=fit_textbox_kwargs,
                 **kwargs
             )
         # Facet mode (legacy path, same=True ignored in facet mode)
@@ -4200,6 +4273,7 @@ def hist(
                 cumulative=cumulative,
                 # Phase 13.42.DF: inline fits (QRC v1.32 #6 recursive forwarding)
                 fit=fit,
+                fit_textbox_kwargs=fit_textbox_kwargs,
                 **kwargs
             )
             axes = ax
@@ -4275,6 +4349,11 @@ def scatter(
         delta_facet: Optional[str] = None,
         # Phase 13.42.DF: Inline fit specification
         fit: Optional[Union[str, Dict, Callable, List]] = None,
+        # Phase 13.42.DF FIX2 (ADV-3, Sonnet55 P2-2 carry-forward):
+        # per-call fit textbox formatting overrides. Pattern B —
+        # forwarded inward; consumed by inner draw_hist/profile/scatter
+        # via render_fit_textbox.
+        fit_textbox_kwargs: Optional[Dict] = None,
         **kwargs
     ) -> DrawResult:
         """
@@ -4477,6 +4556,7 @@ def scatter(
                 share_across_figures=share_across_figures,
                 # Phase 13.42.DF: inline fits
                 fit=fit,
+                fit_textbox_kwargs=fit_textbox_kwargs,
                 **kwargs
             )
         # Facet mode (legacy path, same=True ignored in facet mode)
@@ -4506,6 +4586,7 @@ def scatter(
                 time_format=time_format,
                 # Phase 13.42.DF: inline fits
                 fit=fit,
+                fit_textbox_kwargs=fit_textbox_kwargs,
                 **kwargs
             )
             axes = ax
@@ -4607,6 +4688,11 @@ def profile(
         linestyle_cycle: bool = False,
         # Phase 13.42.DF: Inline fit specification
         fit: Optional[Union[str, Dict, Callable, List]] = None,
+        # Phase 13.42.DF FIX2 (ADV-3, Sonnet55 P2-2 carry-forward):
+        # per-call fit textbox formatting overrides. Pattern B —
+        # forwarded inward; consumed by inner draw_hist/profile/scatter
+        # via render_fit_textbox.
+        fit_textbox_kwargs: Optional[Dict] = None,
         **kwargs
     ) -> DrawResult:
         """
@@ -5114,6 +5200,7 @@ def profile(
                 share_across_figures=share_across_figures,
                 # Phase 13.42.DF: inline fits
                 fit=fit,
+                fit_textbox_kwargs=fit_textbox_kwargs,
                 **kwargs
             )
         else:
@@ -5146,6 +5233,7 @@ def profile(
                 time_format=time_format,
                 # Phase 13.42.DF: inline fits
                 fit=fit,
+                fit_textbox_kwargs=fit_textbox_kwargs,
                 **kwargs
             )
             axes = ax

UTILS/dfextensions/dfdraw/plots/histogram.py

@@ -763,6 +763,28 @@ def draw_hist(
             # → curve_fit minimizes Σresid² as if yerr=1; reported χ² scales with N²).
             # `hist_errors` now controls *display* errorbars only, NOT fit yerr.
             # max(counts, 1) matches ROOT precisely for empty bins.
+            #
+            # Phase 13.42.DF FIX2 (I-8, Sonnet53_R2 v1.0 panel finding, v1.2 §8
+            # B5(c) commitment): when user has weights= AND fit=, χ² uses
+            # sqrt(counts) (UNWEIGHTED Neyman) not sqrt(Σw²) (weighted Poisson).
+            # The errorbar display path (Phase 13.37 CP1-6) DOES use Σw², but
+            # the fit path does not — that's a known limitation. Emit a
+            # one-time UserWarning so analysts choosing weighted hist for QA
+            # know the reported chi² treats weights as if they were counts.
+            if _hist_weights is not None:
+                import warnings as _warnings
+                _warnings.warn(
+                    "Phase 13.42.DF FIX2 (I-8): fit= combined with weights= "
+                    "uses sqrt(counts) Neyman errors, NOT sqrt(Σw²) weighted "
+                    "Poisson. The reported χ²/ndf treats weighted bin contents "
+                    "as if they were raw counts; if you need the weighted "
+                    "Poisson formula, compute it manually from stats['fit'] "
+                    "params and a separate np.histogram(weights=w**2, ...) "
+                    "call. (FIX2 limitation; full sum-of-weights fit deferred "
+                    "to a later phase.)",
+                    UserWarning,
+                    stacklevel=2,
+                )
             yerr_hist = np.sqrt(np.maximum(counts_fit, 1))
             curve = {
                 'x_data': bin_centers_fit,

UTILS/dfextensions/dfdraw/tests/feature_taxonomy.py

@@ -1415,6 +1415,13 @@
             "test_phase_13_42_df_inline_fits.py::TestPhase1342FIX1Regressions::test_f32_stacked_hist_per_group_fits",
             "test_phase_13_42_df_inline_fits.py::TestPhase1342FIX1Regressions::test_f33_fit_textbox_kwargs_fontsize_override",
             "test_phase_13_42_df_inline_fits.py::TestPhase1342FIX1Regressions::test_f33_fit_textbox_kwargs_precedence_over_style",
+            # Phase 13.42.DF FIX2 regressions (close items deferred at FIX1 close)
+            "test_phase_13_42_df_inline_fits.py::TestPhase1342FIX2Regressions::test_f59_suptitle_top_for_title_helper",
+            "test_phase_13_42_df_inline_fits.py::TestPhase1342FIX2Regressions::test_f60_facet_fit_no_crash",
+            "test_phase_13_42_df_inline_fits.py::TestPhase1342FIX2Regressions::test_f61_weighted_hist_fit_userwarning",
+            "test_phase_13_42_df_inline_fits.py::TestPhase1342FIX2Regressions::test_f61_unweighted_hist_fit_no_warning",
+            "test_phase_13_42_df_inline_fits.py::TestPhase1342FIX2Regressions::test_f62_stacked_selection_vector_fit_raises",
+            "test_phase_13_42_df_inline_fits.py::TestPhase1342FIX2Regressions::test_f63_fit_textbox_kwargs_signature_and_forwarded_names",
         ],
     },
 ]