PHASE 13.36.DF — user style kwargs override auto-cycle in group_by path

Closes BUG-013: marker='s', color='red', markersize=10 silently ignored
when group_by was active. The grouped rendering path (profile + hist) used
the per-group color/marker cycle unconditionally, discarding user style
kwargs.

Priority rule (architect 2026-05-20):
  user kwarg > channel auto-cycle > style default
None = 'user did not pass' (matches matplotlib default-color semantics).

Profile fix (plots/profile.py):
  _draw_profile_grouped() signature: add _user_marker, _user_markersize,
    _user_color named params (default None).
  draw_profile() captures _ud_user_marker, _ud_user_markersize, _ud_user_color
    BEFORE the style fill-in at lines 311-321 (which replaces None with
    style defaults). Without pre-fill-in capture, the sentinel arrives as
    'o' even when user passed nothing → cycle override (CODER NOTE §5.1).
  draw_profile() call to _draw_profile_grouped(): pass _user_marker=
    _ud_user_marker etc. (the pre-fill-in captures).
  REMOVED: marker=marker, markersize=markersize from the call.
  REMOVED: profile_kwargs.pop('marker'/'markersize') (nothing left to pop).
  Per-group loop: 'is None' check before palette/marker cycle.
  UserWarning fires ONCE per call (i==0) when color= makes all groups uniform.

Hist fix (plots/histogram.py):
  _draw_hist_grouped() signature: add _user_color named param (default None).
  draw_hist() call to _draw_hist_grouped(): pass _user_color=color.
  draw_hist() body (early, before routing): pop 'marker' from kwargs +
    issue UserWarning. v1.2 spec said pop inside _draw_hist_grouped, but
    that path is only reached for grouped hist — non-grouped/vector path
    would crash ax.hist (AttributeError on marker). Single source of truth
    at draw_hist top (CODER NOTE §5.2).
  Per-group color: sentinel checked in BOTH stacked + overlaid branches.

FORWARDED_NAMES (drawer.py):
  _PROFILE_FORWARDED_NAMES += marker, color, markersize (all 3 are explicit
    params of draw_profile()).
  _HIST_FORWARDED_NAMES += marker, color ONLY (NOT markersize — draw_hist()
    has no markersize explicit param; adding it would crash ax.hist via
    vector path. Sonet51 P1 from v1.2 review).

DFDraw method signatures + bodies (drawer.py):
  DFDraw.profile() += color, marker, markersize params (R6 validator).
  DFDraw.hist() += color, marker params (R6 validator).
  Both bodies forward the params explicitly to draw_profile/draw_hist.
  same=True auto-color injection refactored: (a) assign to local color var
    not kwargs['color'] (collision); (b) skip auto-color when group_by is
    active — preserves pre-13.36 behavior (auto-color was silently dropped
    in grouped path) and prevents false-positive 'indistinguishable'
    UserWarning (CODER NOTE §5.3).

linestyle: out of scope — already works (brainstorm + v0/v1 panel live
tests, 2026-05-20). §9.LS.1 locks current behavior.

Primary use case (TPC/ITS calibration overlay):
  adf.draw('y:row', group_by='drift', group_by_bins=5)
  adf.draw('y:row', group_by='drift', group_by_bins=5,
           same=True, marker='s')

Spec history:
  v1.0 (Sonet50): 3 P1s including 'color not forwarded to grouped path'.
  v1.1 (Sonet50): attempted P1-A fix via profile_kwargs.pop, returns _UNSET
                  unconditionally (color/marker/markersize consumed by
                  explicit signature, not in **kwargs). Sonnet53_R2 [X],
                  Claude48Coder [X].
  v1.2 (Claude48Coder, architect-greenlit takeover): Sonnet53_R2 Option A
                  — local variables, None sentinel.
  v1.2 review: Sonet50 [OK], Sonet51 [!] P1 (markersize crash in hist
               vector path — fixed at code time per architect 'no v1.3'
               directive), Claude40 [✅ APPROVED].

Implementation deviations from v1.2 spec (mandatory disclosure):
  - Edit 17 (NEW): pre-fill-in capture for _ud_user_* — caught at smoke
                   test, not anticipated in spec. §5.1.
  - Edit 18: marker pop moved from _draw_hist_grouped to draw_hist top —
             caught by full regression (96 vector hist failures). §5.2.
  - Edit 15/16: same=True + group_by guard — caught at smoke test, false-
                positive UserWarning. §5.3.

Tests: +10 §9 invariance (SO.1-5, SOH.1-2, LS.1, SC.1, VF.1)
Linux Py3.12 (this env): 810 / 1 / 33 / 1 — 1 failed + 33 skipped are
   pre-existing per Phase 13.35.DF conversation summary.
Expected on architect's Mac Py3.9.6: 843 / 0 / 1.

Author: miranov25

UTILS/dfextensions/dfdraw/drawer.py

@@ -576,6 +576,10 @@ def _auto_label(self, y_expr, x_expr=None):
         'vector_compose', 'delta_facet',
         # Phase 13.33.DF: Normalized differential profiles (AD-80/81/82)
         'normalize', 'normalize_layout',
+        # Phase 13.36.DF: user style override kwargs (BUG-013 fix).
+        # draw_profile() has all 3 as explicit params at lines 162-164;
+        # adding to FORWARDED_NAMES lets vector-dispatch path forward them.
+        'marker', 'color', 'markersize',
     )
 
     _HIST_FORWARDED_NAMES = (
@@ -601,6 +605,16 @@ def _auto_label(self, y_expr, x_expr=None):
         'group_by_bins', 'group_by_quantiles',
         'hist_norm',
         'min_entries',
+        # Phase 13.36.DF: user style override kwargs (BUG-013 fix).
+        # draw_hist() has 'color' as explicit param (consumed by signature);
+        # 'marker' is NOT explicit — flows through **kwargs to _draw_hist_grouped()
+        # where it gets popped + a UserWarning is issued (markers are meaningless
+        # for histograms).
+        # NOTE: 'markersize' deliberately NOT added — draw_hist() has no
+        # markersize explicit param, so adding it would let it flow to ax.hist()
+        # via vector dispatch and crash (matplotlib rejects markersize). Sonet51
+        # P1 from v1.2 review.
+        'marker', 'color',
     )
 
     _SCATTER_FORWARDED_NAMES = (
@@ -3190,6 +3204,16 @@ def hist(
         group_by_quantiles: Optional[int] = None,
         hist_norm: Optional[str] = None,
         min_entries: int = 0,
+        # Phase 13.36.DF: user style overrides for group_by path (BUG-013 fix).
+        # color applies uniformly to all groups. marker is consumed inside
+        # _draw_hist_grouped() with a UserWarning (matplotlib's ax.hist does
+        # not render markers — markers are meaningless for histograms).
+        # NOTE: 'markersize' deliberately absent — draw_hist() has no
+        # corresponding draw_hist() explicit param; adding it to
+        # _HIST_FORWARDED_NAMES would crash ax.hist via vector dispatch.
+        # See PHASE_13_36_DF_v1_2_Proposal §3.3 + Sonet51 P1.
+        color: Optional[str] = None,
+        marker: Optional[str] = None,
         **kwargs
     ) -> DrawResult:
         """
@@ -3315,11 +3339,18 @@ def hist(
 
         # Phase 13.13.DF: Inject color and label for same=True
         # Phase 13.16.DF: _suppress_color_cycle flag (P1-2)
+        # Phase 13.36.DF: color is now explicit param. Two changes:
+        # (1) Assign to local `color`, not `kwargs['color']` (collision with
+        #     explicit forwarding to draw_hist below).
+        # (2) Skip auto-color when group_by is active — same rationale as
+        #     DFDraw.profile() (preserves effective pre-13.36 behavior where
+        #     auto-color was silently dropped in the grouped path).
         _suppress_color_cycle = kwargs.pop('_suppress_color_cycle', False)
         save_auto_title = auto_title
         if same:
-            if 'color' not in kwargs and not _suppress_color_cycle:
-                kwargs['color'] = self._get_next_color()
+            if (color is None and not _suppress_color_cycle
+                    and group_by is None):
+                color = self._get_next_color()
             if 'label' not in kwargs and group_by is None:
                 kwargs['label'] = self._auto_label(col_expr)
             # Suppress title handling — we do it in _handle_same_post
@@ -3408,6 +3439,12 @@ def hist(
                 group_by_quantiles=group_by_quantiles,
                 hist_norm=hist_norm,
                 min_entries=min_entries,
+                # Phase 13.36.DF: user style overrides (color → draw_hist;
+                # marker flows via **kwargs after FORWARDED_NAMES, popped at
+                # _draw_hist_grouped first line). Without explicit forward,
+                # consumed by DFDraw.hist signature and lost.
+                color=color,
+                marker=marker,
                 **kwargs
             )
             axes = ax
@@ -3771,6 +3808,13 @@ def profile(
         # PHASE_13_33_DF_v1_1_Proposal_NormalizedDifferentialProfiles.md.
         normalize: Optional[Union[str, "callable"]] = None,
         normalize_layout: str = "overlay+diff",
+        # Phase 13.36.DF: user style overrides for group_by path (BUG-013 fix).
+        # When passed, applies uniformly to ALL groups in the call (overrides
+        # the per-group auto-cycle). None = use auto-cycle (default).
+        # See PHASE_13_36_DF_v1_2_Proposal_UserStyleOverride.md.
+        color: Optional[str] = None,
+        marker: Optional[str] = None,
+        markersize: Optional[float] = None,
         **kwargs
     ) -> DrawResult:
         """
@@ -4119,11 +4163,22 @@ def profile(
 
         # Phase 13.13.DF: Inject color and label for same=True
         # Phase 13.16.DF: _suppress_color_cycle flag (P1-2)
+        # Phase 13.36.DF: color is now explicit param of DFDraw.profile().
+        # Two changes vs pre-13.36:
+        # (1) Assign auto-color to local `color`, not `kwargs['color']`
+        #     (would collide with explicit forwarding at line ~4262).
+        # (2) Skip auto-color injection when group_by is active. Pre-13.36
+        #     dropped auto-color silently in the grouped path; post-13.36
+        #     it would flow through and force all groups uniform, defeating
+        #     the per-group color cycle. The cycle already distinguishes
+        #     groups; same=True overlay distinguishes via marker (cycle or
+        #     user-passed). This preserves the effective pre-13.36 behavior.
         _suppress_color_cycle = kwargs.pop('_suppress_color_cycle', False)
         save_auto_title = auto_title
         if same:
-            if 'color' not in kwargs and not _suppress_color_cycle:
-                kwargs['color'] = self._get_next_color()
+            if (color is None and not _suppress_color_cycle
+                    and group_by is None):
+                color = self._get_next_color()
             if 'label' not in kwargs and group_by is None:
                 kwargs['label'] = self._auto_label(y_expr, x_expr)
             # Suppress title — handled in _handle_same_post
@@ -4218,6 +4273,11 @@ def profile(
                 quantiles=quantiles, central=central, quantile_mode=quantile_mode,
                 # Phase 13.28.DF: NaN/inf filter policy
                 nan_policy=nan_policy,
+                # Phase 13.36.DF: user style overrides — all three forwarded
+                # from DFDraw.profile() explicit signature. draw_profile() has
+                # all three as explicit params at lines 162-164. Without these,
+                # consumed by DFDraw.profile() signature and lost.
+                color=color, marker=marker, markersize=markersize,
                 **kwargs
             )
             axes = ax

UTILS/dfextensions/dfdraw/plots/histogram.py

@@ -288,7 +288,26 @@ def draw_hist(
         linewidth = get_style_value("hist.linewidth", 1.0)
     # Phase 13.12.DF v1.2: auto_title from style if not set per-call
     auto_title = resolve_auto_title(auto_title)
-    
+
+    # Phase 13.36.DF: pop 'marker' from kwargs BEFORE any rendering path.
+    # 'marker' flows in here via _HIST_FORWARDED_NAMES (Phase 13.36 added it
+    # to the tuple). matplotlib's ax.hist() does NOT accept marker — would
+    # raise AttributeError on every hist render (vector path, non-grouped
+    # path, grouped path). The pop must happen at draw_hist top, not deeper
+    # inside _draw_hist_grouped (which is only reached for the grouped path).
+    # markersize is NOT in _HIST_FORWARDED_NAMES (Sonet51 P1 from v1.2 review)
+    # so it cannot arrive here via the vector path. No pop needed for it.
+    _user_marker = kwargs.pop('marker', None)
+    if _user_marker is not None:
+        import warnings
+        _ht_hint = histtype if histtype is not None else 'bar'
+        warnings.warn(
+            f"marker={_user_marker!r} has no effect on histograms "
+            f"(histtype={_ht_hint!r} — ax.hist does not render markers). "
+            f"Use color= to distinguish groups instead.",
+            UserWarning, stacklevel=3
+        )
+
     # Create figure if needed
     if ax is None:
         figsize = get_style_value("figure.figsize", (8, 6))
@@ -469,6 +488,12 @@ def draw_hist(
             bin_edges=shared_edges,
             hist_norm=hist_norm,
             min_entries=min_entries,
+            # Phase 13.36.DF: forward user color from draw_hist's local variable
+            # (consumed by explicit signature at line ~157, NOT in **kwargs).
+            # Without this, the user's color= silently no-ops in the grouped path
+            # (v1.0 P1-A pattern). marker= still flows through **kwargs to
+            # _draw_hist_grouped where it's popped + warned.
+            _user_color=color,
             density=density, weights=_hist_weights,
             alpha=alpha, histtype=histtype, edgecolor=edgecolor,
             linewidth=linewidth,
@@ -530,15 +555,24 @@ def _draw_hist_grouped(
     bin_edges: Optional[np.ndarray] = None,   # Phase 13.35.DF: shared edges from full dataset
     hist_norm: Optional[str] = None,          # Phase 13.35.DF: None | "probability" | "density"
     min_entries: int = 0,                     # Phase 13.35.DF: skip groups below threshold
+    # Phase 13.36.DF: user color override (None = use per-group palette cycle).
+    # 'color' is consumed by draw_hist()'s explicit signature — must be passed
+    # as a named param from there (not via **kwargs which doesn't contain it).
+    _user_color: Optional[str] = None,
     **hist_kwargs
 ) -> int:
     """Draw grouped/overlaid histograms.
 
     Phase 13.35.DF: extended for float group_by binning + per-group normalization.
+    Phase 13.36.DF: extended for user color override + marker UserWarning.
     Returns the number of groups actually rendered (post min_entries filter).
     """
     import matplotlib.pyplot as plt
 
+    # Phase 13.36.DF: 'marker' is popped earlier in draw_hist() body, so it
+    # cannot arrive here in hist_kwargs. The UserWarning fires once at the
+    # draw_hist level regardless of grouped/non-grouped routing.
+
     # Phase 13.35.DF: pop 'weights' from hist_kwargs — the grouped path uses
     # per-group hist_norm weights (from _group_weights), not the routing
     # block's _hist_weights (which is None on this path anyway because
@@ -564,6 +598,17 @@ def _draw_hist_grouped(
     # Use shared edges if provided; fall back to matplotlib auto-bin (or kwarg)
     bins_arg = bin_edges if bin_edges is not None else hist_kwargs.pop('bins', 100)
 
+    # Phase 13.36.DF: warn ONCE per call when user color= makes all groups
+    # indistinguishable. Fires before either render branch.
+    if _user_color is not None and len(groups) > 1:
+        import warnings
+        warnings.warn(
+            f"color={_user_color!r} applied uniformly to all {len(groups)} groups. "
+            f"Groups will be indistinguishable by color. "
+            f"Omit color= to use per-group colors (default behavior).",
+            UserWarning, stacklevel=3
+        )
+
     if stacked:
         # One-pass loop: build data_list, labels, AND surviving_colors in lockstep
         # so all three stay aligned when min_entries filters drop groups.
@@ -573,6 +618,8 @@ def _draw_hist_grouped(
         # P3 (color-shift) also fixed here: pre-Phase 13.35.DF, colors[:M] gave
         # sequential tab10 colors, not the original-index color per surviving
         # group; surviving_colors[i] preserves the original colors[i] mapping.
+        # Phase 13.36.DF: when _user_color is set, surviving_colors becomes
+        # uniform (user wants all groups same color — already warned above).
         data_list, labels, surviving_colors = [], [], []
         for i, g in enumerate(groups):
             d = df[df[group_by] == g][x].dropna().values.astype(float)
@@ -582,7 +629,10 @@ def _draw_hist_grouped(
                 # _format_interval_label is defined in profile.py and NOT
                 # imported here. (v1.1 P1-A from review panel.)
                 labels.append(str(g))
-                surviving_colors.append(colors[i])
+                # Phase 13.36.DF: user override > palette.
+                surviving_colors.append(
+                    colors[i] if _user_color is None else _user_color
+                )
         if not data_list:
             return 0
         ax.hist(data_list, bins=bins_arg, label=labels,
@@ -592,16 +642,19 @@ def _draw_hist_grouped(
         # Overlaid histograms — one ax.hist call per surviving group.
         # colors[i] preserves original-index color when groups are skipped
         # (overlaid branch was already correct in baseline; documented for parity).
+        # Phase 13.36.DF: user override > palette per group.
         n_rendered = 0
         for i, group in enumerate(groups):
             # BUG_dfdraw_20260505: cast to float for boolean expressions
             group_data = df[df[group_by] == group][x].dropna().values.astype(float)
             if len(group_data) < min_entries:
                 continue
             weights = _group_weights(group_data, bin_edges, hist_norm)
+            # Phase 13.36.DF: user override > palette
+            group_color = colors[i] if _user_color is None else _user_color
             # Label via str(group) — not _format_interval_label. (v1.1 P1-A)
             ax.hist(group_data, bins=bins_arg,
-                    label=str(group), color=colors[i],
+                    label=str(group), color=group_color,
                     weights=weights, **hist_kwargs)
             n_rendered += 1   # count post-skip (v1.1 P1-C from review panel)
         if n_rendered > 0:

UTILS/dfextensions/dfdraw/plots/profile.py

@@ -308,6 +308,16 @@ def draw_profile(
         context="profile",
     )
 
+    # Phase 13.36.DF: capture user-explicit marker/markersize BEFORE the style
+    # fill-in below (which sets marker='o', markersize=6 when user passed None).
+    # We need to distinguish "user explicitly passed marker='s'" from "user
+    # passed nothing; style filled in default 'o'". The grouped path uses
+    # these to decide between uniform-override vs per-group cycle.
+    # color is NOT filled in by style (matplotlib handles None directly).
+    _ud_user_marker = marker          # None or user's value
+    _ud_user_markersize = markersize  # None or user's value
+    _ud_user_color = color            # None or user's value
+
     # Get style defaults
     if bins is None:
         bins = get_style_value("hist.bins", 50)
@@ -485,8 +495,20 @@ def draw_profile(
         # discrete lines per group color; see _draw_profile_grouped docstring.
         profile_data_list, _per_group_stats = _draw_profile_grouped(
             df_filtered, x, y, ax, group_col, top_k,
+            # Phase 13.36.DF: forward user style overrides as named params
+            # (BUG-013 fix). The user's marker/markersize/color values live in
+            # draw_profile()'s LOCAL VARIABLES — but the style fill-in above
+            # at lines 314-317 replaces None with style defaults BEFORE this
+            # call. Use the _ud_user_* captures (None when user passed nothing)
+            # to correctly distinguish explicit-pass from style-fill.
+            _user_marker=_ud_user_marker,
+            _user_markersize=_ud_user_markersize,
+            _user_color=_ud_user_color,
             bins=bins, x_range=_used_xrange, error=error,
-            marker=marker, markersize=markersize, capsize=capsize,
+            # Phase 13.36.DF: marker= and markersize= REMOVED from this call.
+            # They are now forwarded via _user_marker / _user_markersize above.
+            # The previous pops at lines 984-985 are also deleted (nothing to pop).
+            capsize=capsize,
             linestyle=linestyle, linewidth=linewidth,
             min_entries=min_entries,
             sort_groups=sort_groups,
@@ -913,6 +935,13 @@ def _draw_profile_grouped(
     quantile_pair: Optional[tuple] = None,
     quantile_list: Optional[list] = None,
     quantile_style: Optional[str] = None,
+    # Phase 13.36.DF: user style overrides (BUG-013 fix).
+    # None = "user did not pass" (matches matplotlib default-color semantics).
+    # Non-None = apply uniformly to all groups, override the auto-cycle.
+    # See module-level docstring for design rationale.
+    _user_marker: Optional[str] = None,
+    _user_markersize: Optional[float] = None,
+    _user_color: Optional[str] = None,
     **profile_kwargs
 ) -> tuple:
     """
@@ -980,9 +1009,13 @@ def _draw_profile_grouped(
     x_range = profile_kwargs.pop('x_range', None)
     error = profile_kwargs.pop('error', 'sem')
     linewidth = profile_kwargs.get('linewidth', 1.5)
-    # Remove marker/markersize from kwargs - we use fmt and dedicated markers
-    profile_kwargs.pop('marker', None)
-    profile_kwargs.pop('markersize', None)
+    # Phase 13.36.DF: pops for 'marker' and 'markersize' DELETED. These values
+    # are now forwarded as _user_marker / _user_markersize named params from
+    # draw_profile() (the local variables where the user's values live after
+    # consumption by draw_profile()'s explicit signature). The call site at
+    # line 489 no longer passes marker=marker / markersize=markersize.
+    # Both vector and non-vector paths route the values through _user_* params.
+    # → Nothing reaches profile_kwargs to pop.
 
     # Phase 13.12.DF F1: Collect profile data
     profile_data_list = [] if return_data else None
@@ -1028,7 +1061,22 @@ def _draw_profile_grouped(
         # Phase 13.12.DF F2: Apply min_entries filter for plotting
         plot_mask = bin_counts >= min_entries
 
-        group_color = palette(i % 10)
+        # Phase 13.36.DF: user color override > palette cycle.
+        # None = "user did not pass" (matches matplotlib default-color semantics).
+        group_color = (palette(i % 10)
+                       if _user_color is None
+                       else _user_color)
+
+        # Phase 13.36.DF: warn ONCE per call (i == 0) when color= makes all
+        # groups indistinguishable. Architect decision 2026-05-20.
+        if i == 0 and _user_color is not None and len(groups) > 1:
+            import warnings
+            warnings.warn(
+                f"color={_user_color!r} applied uniformly to all {len(groups)} groups. "
+                f"Groups will be indistinguishable by color. "
+                f"Omit color= to use per-group colors (default behavior).",
+                UserWarning, stacklevel=4
+            )
 
         # Phase 13.32.DF Sub-fix 2: per-group quantile rendering BEFORE the
         # central line so the central line stays visually on top.
@@ -1073,10 +1121,16 @@ def _draw_profile_grouped(
                 per_group_stats[group]['quantiles_per_bin'] = _q_all
 
         # Central line (mean or median) — always rendered last so it sits on top
+        # Phase 13.36.DF: user marker/markersize override > cycle.
+        # None on either passes through to matplotlib defaults (correct).
+        group_marker = (markers[i % len(markers)]
+                        if _user_marker is None
+                        else _user_marker)
         ax.errorbar(
             bin_centers[plot_mask], bin_means[plot_mask], yerr=bin_errors[plot_mask],
-            fmt=markers[i % len(markers)],
+            fmt=group_marker,
             color=group_color,
+            markersize=_user_markersize,   # None → matplotlib default
             # If quantiles already added a legend entry for this group, suppress
             # the duplicate central-line legend entry by setting label=None.
             label=(None if quantiles is not None and quantile_list is not None