Finalize MDFC follow-ups, docs, and diagnostics tooling

document deck summary DFC badges, exporter annotations, and per-face metadata across README/DOCKER/release notes

record completion of all MDFC roadmap follow-ups and add the authoring guide for multi-face CSV entries

wire in optional DFC_PER_FACE_SNAPSHOT env support, exporter regression tests, and diagnostics updates noted in the changelog

code/web/app.py

@@ -15,6 +15,9 @@ from starlette.exceptions import HTTPException as StarletteHTTPException
 from starlette.middleware.gzip import GZipMiddleware
 from typing import Any, Optional, Dict, Iterable, Mapping
 from contextlib import asynccontextmanager
+
+from code.deck_builder.summary_telemetry import get_mdfc_metrics
+from tagging.multi_face_merger import load_merge_summary
 from .services.combo_utils import detect_all as _detect_all
 from .services.theme_catalog_loader import prewarm_common_filters  # type: ignore
 from .services.tasks import get_session, new_sid, set_session_value  # type: ignore
@@ -873,6 +876,17 @@ async def status_random_theme_stats():
         return JSONResponse({"ok": False, "error": "internal_error"}, status_code=500)
 
 
+@app.get("/status/dfc_metrics")
+async def status_dfc_metrics():
+    if not SHOW_DIAGNOSTICS:
+        raise HTTPException(status_code=404, detail="Not Found")
+    try:
+        return JSONResponse({"ok": True, "metrics": get_mdfc_metrics()})
+    except Exception as exc:  # pragma: no cover - defensive log
+        logging.getLogger("web").warning("Failed to fetch MDFC metrics: %s", exc, exc_info=True)
+        return JSONResponse({"ok": False, "error": "internal_error"}, status_code=500)
+
+
 def random_modes_enabled() -> bool:
     """Dynamic check so tests that set env after import still work.
 
@@ -2352,7 +2366,13 @@ async def trigger_error(kind: str = Query("http")):
 async def diagnostics_home(request: Request) -> HTMLResponse:
     if not SHOW_DIAGNOSTICS:
         raise HTTPException(status_code=404, detail="Not Found")
-    return templates.TemplateResponse("diagnostics/index.html", {"request": request})
+    return templates.TemplateResponse(
+        "diagnostics/index.html",
+        {
+            "request": request,
+            "merge_summary": load_merge_summary(),
+        },
+    )
 
 
 @app.get("/diagnostics/perf", response_class=HTMLResponse)

code/web/routes/build.py

@@ -27,6 +27,7 @@ from path_util import csv_dir as _csv_dir
 from ..services.alts_utils import get_cached as _alts_get_cached, set_cached as _alts_set_cached
 from ..services.telemetry import log_commander_create_deck
 from urllib.parse import urlparse
+from commander_exclusions import lookup_commander_detail
 
 # Cache for available card names used by validation endpoints
 _AVAILABLE_CARDS_CACHE: set[str] | None = None
@@ -150,6 +151,7 @@ def _rebuild_ctx_with_multicopy(sess: dict) -> None:
             prefer_combos=bool(sess.get("prefer_combos")),
             combo_target_count=int(sess.get("combo_target_count", 2)),
             combo_balance=str(sess.get("combo_balance", "mix")),
+            swap_mdfc_basics=bool(sess.get("swap_mdfc_basics")),
         )
     except Exception:
         # If rebuild fails (e.g., commander not found in test), fall back to injecting
@@ -415,12 +417,22 @@ async def multicopy_save(
 async def build_new_modal(request: Request) -> HTMLResponse:
     """Return the New Deck modal content (for an overlay)."""
     sid = request.cookies.get("sid") or new_sid()
+    sess = get_session(sid)
     ctx = {
         "request": request,
         "brackets": orch.bracket_options(),
         "labels": orch.ideal_labels(),
         "defaults": orch.ideal_defaults(),
         "allow_must_haves": ALLOW_MUST_HAVES,  # Add feature flag
+        "form": {
+            "prefer_combos": bool(sess.get("prefer_combos")),
+            "combo_count": sess.get("combo_target_count"),
+            "combo_balance": sess.get("combo_balance"),
+            "enable_multicopy": bool(sess.get("multi_copy")),
+            "use_owned_only": bool(sess.get("use_owned_only")),
+            "prefer_owned": bool(sess.get("prefer_owned")),
+            "swap_mdfc_basics": bool(sess.get("swap_mdfc_basics")),
+        },
     }
     resp = templates.TemplateResponse("build/_new_deck_modal.html", ctx)
     resp.set_cookie("sid", sid, httponly=True, samesite="lax")
@@ -432,7 +444,38 @@ async def build_new_candidates(request: Request, commander: str = Query("")) ->
     """Return a small list of commander candidates for the modal live search."""
     q = (commander or "").strip()
     items = orch.commander_candidates(q, limit=8) if q else []
-    ctx = {"request": request, "query": q, "candidates": items}
+    candidates: list[dict[str, Any]] = []
+    for name, score, colors in items:
+        detail = lookup_commander_detail(name)
+        preferred = name
+        warning = None
+        if detail:
+            eligible_raw = detail.get("eligible_faces")
+            eligible = [str(face).strip() for face in eligible_raw or [] if str(face).strip()] if isinstance(eligible_raw, list) else []
+            norm_name = str(name).strip().casefold()
+            eligible_norms = [face.casefold() for face in eligible]
+            if eligible and norm_name not in eligible_norms:
+                preferred = eligible[0]
+                primary = str(detail.get("primary_face") or detail.get("name") or name).strip()
+                if len(eligible) == 1:
+                    warning = (
+                        f"Use the back face '{preferred}' when building. Front face '{primary}' can't lead a deck."
+                    )
+                else:
+                    faces = ", ".join(f"'{face}'" for face in eligible)
+                    warning = (
+                        f"This commander only works from specific faces: {faces}."
+                    )
+        candidates.append(
+            {
+                "display": name,
+                "value": preferred,
+                "score": score,
+                "colors": colors,
+                "warning": warning,
+            }
+        )
+    ctx = {"request": request, "query": q, "candidates": candidates}
     return templates.TemplateResponse("build/_new_deck_candidates.html", ctx)
 
 
@@ -445,6 +488,7 @@ async def build_new_inspect(request: Request, name: str = Query(...)) -> HTMLRes
     tags = orch.tags_for_commander(info["name"]) or []
     recommended = orch.recommended_tags_for_commander(info["name"]) if tags else []
     recommended_reasons = orch.recommended_tag_reasons_for_commander(info["name"]) if tags else {}
+    exclusion_detail = lookup_commander_detail(info["name"])
     # Render tags slot content and OOB commander preview simultaneously
     # Game Changer flag for this commander (affects bracket UI in modal via tags partial consumer)
     is_gc = False
@@ -454,7 +498,7 @@ async def build_new_inspect(request: Request, name: str = Query(...)) -> HTMLRes
         is_gc = False
     ctx = {
         "request": request,
-        "commander": {"name": info["name"]},
+        "commander": {"name": info["name"], "exclusion": exclusion_detail},
         "tags": tags,
         "recommended": recommended,
         "recommended_reasons": recommended_reasons,
@@ -553,6 +597,9 @@ async def build_new_submit(
     combo_count: int | None = Form(None),
     combo_balance: str | None = Form(None),
     enable_multicopy: bool = Form(False),
+    use_owned_only: bool = Form(False),
+    prefer_owned: bool = Form(False),
+    swap_mdfc_basics: bool = Form(False),
     # Integrated Multi-Copy (optional)
     multi_choice_id: str | None = Form(None),
     multi_count: int | None = Form(None),
@@ -567,6 +614,57 @@ async def build_new_submit(
     """Handle New Deck modal submit and immediately start the build (skip separate review page)."""
     sid = request.cookies.get("sid") or new_sid()
     sess = get_session(sid)
+
+    def _form_state(commander_value: str) -> dict[str, Any]:
+        return {
+            "name": name,
+            "commander": commander_value,
+            "primary_tag": primary_tag or "",
+            "secondary_tag": secondary_tag or "",
+            "tertiary_tag": tertiary_tag or "",
+            "tag_mode": tag_mode or "AND",
+            "bracket": bracket,
+            "combo_count": combo_count,
+            "combo_balance": (combo_balance or "mix"),
+            "prefer_combos": bool(prefer_combos),
+            "enable_multicopy": bool(enable_multicopy),
+            "use_owned_only": bool(use_owned_only),
+            "prefer_owned": bool(prefer_owned),
+            "swap_mdfc_basics": bool(swap_mdfc_basics),
+            "include_cards": include_cards or "",
+            "exclude_cards": exclude_cards or "",
+            "enforcement_mode": enforcement_mode or "warn",
+            "allow_illegal": bool(allow_illegal),
+            "fuzzy_matching": bool(fuzzy_matching),
+        }
+
+    commander_detail = lookup_commander_detail(commander)
+    if commander_detail:
+        eligible_raw = commander_detail.get("eligible_faces")
+        eligible_faces = [str(face).strip() for face in eligible_raw or [] if str(face).strip()] if isinstance(eligible_raw, list) else []
+        if eligible_faces:
+            norm_input = str(commander).strip().casefold()
+            eligible_norms = [face.casefold() for face in eligible_faces]
+            if norm_input not in eligible_norms:
+                suggested = eligible_faces[0]
+                primary_face = str(commander_detail.get("primary_face") or commander_detail.get("name") or commander).strip()
+                faces_str = ", ".join(f"'{face}'" for face in eligible_faces)
+                error_msg = (
+                    f"'{primary_face or commander}' can't lead a deck. Use {faces_str} as the commander instead. "
+                    "We've updated the commander field for you."
+                )
+                ctx = {
+                    "request": request,
+                    "error": error_msg,
+                    "brackets": orch.bracket_options(),
+                    "labels": orch.ideal_labels(),
+                    "defaults": orch.ideal_defaults(),
+                    "allow_must_haves": ALLOW_MUST_HAVES,
+                    "form": _form_state(suggested),
+                }
+                resp = templates.TemplateResponse("build/_new_deck_modal.html", ctx)
+                resp.set_cookie("sid", sid, httponly=True, samesite="lax")
+                return resp
     # Normalize and validate commander selection (best-effort via orchestrator)
     sel = orch.commander_select(commander)
     if not sel.get("ok"):
@@ -578,23 +676,7 @@ async def build_new_submit(
             "labels": orch.ideal_labels(),
             "defaults": orch.ideal_defaults(),
             "allow_must_haves": ALLOW_MUST_HAVES,  # Add feature flag
-            "form": {
-                "name": name,
-                "commander": commander,
-                "primary_tag": primary_tag or "",
-                "secondary_tag": secondary_tag or "",
-                "tertiary_tag": tertiary_tag or "",
-                "tag_mode": tag_mode or "AND",
-                "bracket": bracket,
-                "combo_count": combo_count,
-                "combo_balance": (combo_balance or "mix"),
-                "prefer_combos": bool(prefer_combos),
-                "include_cards": include_cards or "",
-                "exclude_cards": exclude_cards or "",
-                "enforcement_mode": enforcement_mode or "warn",
-                "allow_illegal": bool(allow_illegal),
-                "fuzzy_matching": bool(fuzzy_matching),
-            }
+            "form": _form_state(commander),
         }
         resp = templates.TemplateResponse("build/_new_deck_modal.html", ctx)
         resp.set_cookie("sid", sid, httponly=True, samesite="lax")
@@ -654,6 +736,18 @@ async def build_new_submit(
         sess["prefer_combos"] = bool(prefer_combos)
     except Exception:
         sess["prefer_combos"] = False
+    try:
+        sess["use_owned_only"] = bool(use_owned_only)
+    except Exception:
+        sess["use_owned_only"] = False
+    try:
+        sess["prefer_owned"] = bool(prefer_owned)
+    except Exception:
+        sess["prefer_owned"] = False
+    try:
+        sess["swap_mdfc_basics"] = bool(swap_mdfc_basics)
+    except Exception:
+        sess["swap_mdfc_basics"] = False
     # Combos config from modal
     try:
         if combo_count is not None:
@@ -1267,6 +1361,9 @@ async def build_step3_submit(
             "labels": labels,
             "values": submitted,
             "commander": sess.get("commander"),
+            "owned_only": bool(sess.get("use_owned_only")),
+            "prefer_owned": bool(sess.get("prefer_owned")),
+            "swap_mdfc_basics": bool(sess.get("swap_mdfc_basics")),
         },
     )
     resp.set_cookie("sid", sid, httponly=True, samesite="lax")
@@ -1313,6 +1410,7 @@ async def build_step4_get(request: Request) -> HTMLResponse:
             "commander": commander,
             "owned_only": bool(sess.get("use_owned_only")),
             "prefer_owned": bool(sess.get("prefer_owned")),
+            "swap_mdfc_basics": bool(sess.get("swap_mdfc_basics")),
         },
     )
 
@@ -1485,6 +1583,7 @@ async def build_toggle_owned_review(
     request: Request,
     use_owned_only: str | None = Form(None),
     prefer_owned: str | None = Form(None),
+    swap_mdfc_basics: str | None = Form(None),
 ) -> HTMLResponse:
     """Toggle 'use owned only' and/or 'prefer owned' flags from the Review step and re-render Step 4."""
     sid = request.cookies.get("sid") or new_sid()
@@ -1492,8 +1591,10 @@ async def build_toggle_owned_review(
     sess["last_step"] = 4
     only_val = True if (use_owned_only and str(use_owned_only).strip() in ("1","true","on","yes")) else False
     pref_val = True if (prefer_owned and str(prefer_owned).strip() in ("1","true","on","yes")) else False
+    swap_val = True if (swap_mdfc_basics and str(swap_mdfc_basics).strip() in ("1","true","on","yes")) else False
     sess["use_owned_only"] = only_val
     sess["prefer_owned"] = pref_val
+    sess["swap_mdfc_basics"] = swap_val
     # Do not touch build_ctx here; user hasn't started the build yet from review
     labels = orch.ideal_labels()
     values = sess.get("ideals") or orch.ideal_defaults()
@@ -1507,6 +1608,7 @@ async def build_toggle_owned_review(
             "commander": commander,
             "owned_only": bool(sess.get("use_owned_only")),
             "prefer_owned": bool(sess.get("prefer_owned")),
+            "swap_mdfc_basics": bool(sess.get("swap_mdfc_basics")),
         },
     )
     resp.set_cookie("sid", sid, httponly=True, samesite="lax")
@@ -2888,6 +2990,7 @@ async def build_permalink(request: Request):
         "flags": {
             "owned_only": bool(sess.get("use_owned_only")),
             "prefer_owned": bool(sess.get("prefer_owned")),
+            "swap_mdfc_basics": bool(sess.get("swap_mdfc_basics")),
         },
         "locks": list(sess.get("locks", [])),
     }
@@ -2974,6 +3077,7 @@ async def build_from(request: Request, state: str | None = None) -> HTMLResponse
             flags = data.get("flags") or {}
             sess["use_owned_only"] = bool(flags.get("owned_only"))
             sess["prefer_owned"] = bool(flags.get("prefer_owned"))
+            sess["swap_mdfc_basics"] = bool(flags.get("swap_mdfc_basics"))
             sess["locks"] = list(data.get("locks", []))
             # Optional random build rehydration
             try:
@@ -3037,6 +3141,7 @@ async def build_from(request: Request, state: str | None = None) -> HTMLResponse
         "commander": sess.get("commander"),
         "owned_only": bool(sess.get("use_owned_only")),
         "prefer_owned": bool(sess.get("prefer_owned")),
+        "swap_mdfc_basics": bool(sess.get("swap_mdfc_basics")),
         "locks_restored": locks_restored,
     })
     resp.set_cookie("sid", sid, httponly=True, samesite="lax")

code/web/routes/commanders.py

@@ -528,3 +528,13 @@ async def commanders_index(
     except Exception:
         pass
     return templates.TemplateResponse(template_name, context)
+
+@router.get("", response_class=HTMLResponse)
+async def commanders_index_alias(
+    request: Request,
+    q: str | None = Query(default=None, alias="q"),
+    theme: str | None = Query(default=None, alias="theme"),
+    color: str | None = Query(default=None, alias="color"),
+    page: int = Query(default=1, ge=1),
+) -> HTMLResponse:
+    return await commanders_index(request, q=q, theme=theme, color=color, page=page)

code/web/services/build_utils.py

@@ -27,6 +27,7 @@ def step5_base_ctx(request: Request, sess: dict, *, include_name: bool = True, i
         "prefer_combos": bool(sess.get("prefer_combos")),
         "combo_target_count": int(sess.get("combo_target_count", 2)),
         "combo_balance": str(sess.get("combo_balance", "mix")),
+        "swap_mdfc_basics": bool(sess.get("swap_mdfc_basics")),
     }
     if include_name:
         ctx["name"] = sess.get("custom_export_base")
@@ -85,6 +86,7 @@ def start_ctx_from_session(sess: dict, *, set_on_session: bool = True) -> Dict[s
         combo_balance=str(sess.get("combo_balance", "mix")),
         include_cards=sess.get("include_cards"),
         exclude_cards=sess.get("exclude_cards"),
+        swap_mdfc_basics=bool(sess.get("swap_mdfc_basics")),
     )
     if set_on_session:
         sess["build_ctx"] = ctx

code/web/services/orchestrator.py

@@ -1847,6 +1847,7 @@ def start_build_ctx(
     combo_balance: str | None = None,
     include_cards: List[str] | None = None,
     exclude_cards: List[str] | None = None,
+    swap_mdfc_basics: bool | None = None,
 ) -> Dict[str, Any]:
     logs: List[str] = []
 
@@ -1914,6 +1915,11 @@ def start_build_ctx(
     except Exception:
         pass
 
+    try:
+        b.swap_mdfc_basics = bool(swap_mdfc_basics)
+    except Exception:
+        pass
+
     # Data load
     b.determine_color_identity()
     b.setup_dataframes()
@@ -1980,6 +1986,7 @@ def start_build_ctx(
     "history": [],  # list of {i, key, label, snapshot}
         "locks": {str(n).strip().lower() for n in (locks or []) if str(n).strip()},
     "custom_export_base": str(custom_export_base).strip() if isinstance(custom_export_base, str) and custom_export_base.strip() else None,
+        "swap_mdfc_basics": bool(swap_mdfc_basics),
     }
     return ctx
 

code/web/templates/base.html

@@ -662,7 +662,7 @@
         window.__dfcFlipCard = function(card){ if(!card) return; flip(card, card.querySelector('.dfc-toggle')); };
         window.__dfcGetFace = function(card){ if(!card) return 'front'; return card.getAttribute(FACE_ATTR) || 'front'; };
         function scan(){
-          document.querySelectorAll('.card-sample, .commander-cell, .card-tile, .candidate-tile, .stack-card, .card-preview, .owned-row, .list-row').forEach(ensureButton);
+          document.querySelectorAll('.card-sample, .commander-cell, .commander-thumb, .card-tile, .candidate-tile, .stack-card, .card-preview, .owned-row, .list-row').forEach(ensureButton);
         }
         document.addEventListener('pointermove', function(e){ window.__lastPointerEvent = e; }, { passive:true });
         document.addEventListener('DOMContentLoaded', scan);
@@ -1206,9 +1206,9 @@
           if(!el) return null;
           // If inside flip button
           var btn = el.closest && el.closest('.dfc-toggle');
-          if(btn) return btn.closest('.card-sample, .commander-cell, .card-tile, .candidate-tile, .card-preview, .stack-card');
+          if(btn) return btn.closest('.card-sample, .commander-cell, .commander-thumb, .card-tile, .candidate-tile, .card-preview, .stack-card');
           // Recognized container classes (add .stack-card for finished/random deck thumbnails)
-          var container = el.closest && el.closest('.card-sample, .commander-cell, .card-tile, .candidate-tile, .card-preview, .stack-card');
+          var container = el.closest && el.closest('.card-sample, .commander-cell, .commander-thumb, .card-tile, .candidate-tile, .card-preview, .stack-card');
           if(container) return container;
           // Image-based detection (any card image carrying data-card-name)
           if(el.matches && (el.matches('img.card-thumb') || el.matches('img[data-card-name]') || el.classList.contains('commander-img'))){
@@ -1264,12 +1264,12 @@
         window.hoverShowByName = function(name){
           try {
             var el = document.querySelector('[data-card-name="'+CSS.escape(name)+'"]');
-            if(el){ window.__hoverShowCard(el.closest('.card-sample, .commander-cell, .card-tile, .candidate-tile, .card-preview, .stack-card') || el); }
+            if(el){ window.__hoverShowCard(el.closest('.card-sample, .commander-cell, .commander-thumb, .card-tile, .candidate-tile, .card-preview, .stack-card') || el); }
           } catch(_) {}
         };
         // Keyboard accessibility & focus traversal (P2 UI Hover keyboard accessibility)
-        document.addEventListener('focusin', function(e){ var card=e.target.closest && e.target.closest('.card-sample, .commander-cell'); if(card){ show(card, {clientX:card.getBoundingClientRect().left+10, clientY:card.getBoundingClientRect().top+10}); }});
-        document.addEventListener('focusout', function(e){ var next=e.relatedTarget && e.relatedTarget.closest && e.relatedTarget.closest('.card-sample, .commander-cell'); if(!next) hide(); });
+  document.addEventListener('focusin', function(e){ var card=e.target.closest && e.target.closest('.card-sample, .commander-cell, .commander-thumb'); if(card){ show(card, {clientX:card.getBoundingClientRect().left+10, clientY:card.getBoundingClientRect().top+10}); }});
+  document.addEventListener('focusout', function(e){ var next=e.relatedTarget && e.relatedTarget.closest && e.relatedTarget.closest('.card-sample, .commander-cell, .commander-thumb'); if(!next) hide(); });
         document.addEventListener('keydown', function(e){ if(e.key==='Escape') hide(); });
         // Compact mode event listener
         document.addEventListener('mtg:hoverCompactToggle', function(){ panel.classList.toggle('compact-img', !!window.__hoverCompactMode); });

code/web/templates/build/_new_deck_candidates.html

@@ -1,13 +1,19 @@
 {% if candidates and candidates|length %}
 <ul style="list-style:none; padding:0; margin:.35rem 0; display:grid; gap:.25rem;" role="listbox" aria-label="Commander suggestions" tabindex="-1">
-  {% for name, score, colors in candidates %}
+  {% for cand in candidates %}
   <li>
-    <button type="button" id="cand-{{ loop.index0 }}" class="chip candidate-btn" role="option" data-idx="{{ loop.index0 }}" data-name="{{ name|e }}"
-            hx-get="/build/new/inspect?name={{ name|urlencode }}"
+    <button type="button" id="cand-{{ loop.index0 }}" class="chip candidate-btn" role="option" data-idx="{{ loop.index0 }}" data-name="{{ cand.value|e }}" data-display="{{ cand.display|e }}"
+      hx-get="/build/new/inspect?name={{ cand.display|urlencode }}"
             hx-target="#newdeck-tags-slot" hx-swap="innerHTML"
-            hx-on="htmx:afterOnLoad: (function(){ try{ var n=this.getAttribute('data-name')||''; var ci = document.querySelector('input[name=commander]'); if(ci){ ci.value=n; try{ ci.selectionStart = ci.selectionEnd = ci.value.length; }catch(_){} } var nm = document.querySelector('input[name=name]'); if(nm && (!nm.value || !nm.value.trim())){ nm.value=n; } }catch(_){ } }).call(this)">
-      {{ name }}
+            hx-on="htmx:afterOnLoad: (function(){ try{ var preferred=this.getAttribute('data-name')||''; var displayed=this.getAttribute('data-display')||preferred; var ci = document.querySelector('input[name=commander]'); if(ci){ ci.value=preferred; try{ ci.selectionStart = ci.selectionEnd = ci.value.length; }catch(_){} try{ ci.dispatchEvent(new Event('input', { bubbles: true })); }catch(_){ } } var nm = document.querySelector('input[name=name]'); if(nm && (!nm.value || !nm.value.trim())){ nm.value=displayed; } }catch(_){ } }).call(this)">
+      {{ cand.display }}
+      {% if cand.warning %}
+        <span aria-hidden="true" style="margin-left:.35rem; font-size:11px; color:#facc15;">⚠</span>
+      {% endif %}
     </button>
+    {% if cand.warning %}
+      <div class="muted" style="font-size:11px; margin:.25rem 0 0 .5rem; color:#facc15;" role="note">⚠ {{ cand.warning }}</div>
+    {% endif %}
   </li>
   {% endfor %}
 </ul>

code/web/templates/build/_new_deck_modal.html

@@ -55,9 +55,9 @@
       <fieldset>
         <legend>Preferences</legend>
         <div style="text-align: left;">
-          <div style="margin-bottom: 1rem;">
-            <label style="display: inline-flex; align-items: center; gap: 0.5rem; margin: 0;" title="When enabled, the builder will try to auto-complete missing combo partners near the end of the build (respecting owned-only and locks).">
-              <input type="checkbox" name="prefer_combos" id="pref-combos-chk" style="margin: 0;" />
+          <div style="margin-bottom: 1rem; display:flex; flex-direction:column; gap:0.75rem;">
+            <label for="pref-combos-chk" style="display:grid; grid-template-columns:auto 1fr; align-items:center; column-gap:0.5rem; margin:0; width:100%; cursor:pointer; text-align:left;" title="When enabled, the builder will try to auto-complete missing combo partners near the end of the build (respecting owned-only and locks).">
+              <input type="checkbox" name="prefer_combos" id="pref-combos-chk" value="1" style="margin:0; cursor:pointer;" {% if form and form.prefer_combos %}checked{% endif %} />
               <span>Prioritize combos</span>
             </label>
             <div id="pref-combos-config" style="margin-top: 0.5rem; margin-left: 1.5rem; padding: 0.5rem; border: 1px solid var(--border); border-radius: 8px; display: none;">
@@ -80,12 +80,24 @@
                 </div>
               </div>
             </div>
-          </div>
-          <div style="margin-bottom: 1rem;">
-            <label style="display: inline-flex; align-items: center; gap: 0.5rem; margin: 0;" title="When enabled, include a Multi-Copy package for matching archetypes (e.g., tokens/tribal).">
-              <input type="checkbox" name="enable_multicopy" id="pref-mc-chk" style="margin: 0;" />
+            <label for="pref-mc-chk" style="display:grid; grid-template-columns:auto 1fr; align-items:center; column-gap:0.5rem; margin:0; width:100%; cursor:pointer; text-align:left;" title="When enabled, include a Multi-Copy package for matching archetypes (e.g., tokens/tribal).">
+              <input type="checkbox" name="enable_multicopy" id="pref-mc-chk" value="1" style="margin:0; cursor:pointer;" {% if form and form.enable_multicopy %}checked{% endif %} />
               <span>Enable Multi-Copy package</span>
             </label>
+            <div style="display:flex; flex-direction:column; gap:0.5rem; margin-top:0.75rem;">
+              <label for="use-owned-chk" style="display:grid; grid-template-columns:auto 1fr; align-items:center; column-gap:0.5rem; margin:0; width:100%; cursor:pointer; text-align:left;" title="Limit the pool to cards you already own. Cards outside your owned library will be skipped.">
+                <input type="checkbox" name="use_owned_only" id="use-owned-chk" value="1" style="margin:0; cursor:pointer;" {% if form and form.use_owned_only %}checked{% endif %} />
+                <span>Use only owned cards</span>
+              </label>
+              <label for="prefer-owned-chk" style="display:grid; grid-template-columns:auto 1fr; align-items:center; column-gap:0.5rem; margin:0; width:100%; cursor:pointer; text-align:left;" title="Still allow unowned cards, but rank owned cards higher when choosing picks.">
+                <input type="checkbox" name="prefer_owned" id="prefer-owned-chk" value="1" style="margin:0; cursor:pointer;" {% if form and form.prefer_owned %}checked{% endif %} />
+                <span>Prefer owned cards (allow unowned fallback)</span>
+              </label>
+              <label for="swap-mdfc-chk" style="display:grid; grid-template-columns:auto 1fr; align-items:center; column-gap:0.5rem; margin:0; width:100%; cursor:pointer; text-align:left;" title="When enabled, modal DFC lands will replace a matching basic land as they are added so land counts stay level without manual trims.">
+                <input type="checkbox" name="swap_mdfc_basics" id="swap-mdfc-chk" value="1" style="margin:0; cursor:pointer;" {% if form and form.swap_mdfc_basics %}checked{% endif %} />
+                <span>Swap basics for MDFC lands</span>
+              </label>
+            </div>
           </div>
         </div>
       </fieldset>

code/web/templates/build/_new_deck_tags.html

@@ -15,6 +15,27 @@
   </script>
 </div>
 
+{% set exclusion = commander.exclusion if commander is defined and commander.exclusion is defined else None %}
+{% if exclusion %}
+  {% set eligible_raw = exclusion.eligible_faces if exclusion.eligible_faces is defined else [] %}
+  {% set eligible_list = eligible_raw if eligible_raw is iterable else [] %}
+  {% set eligible_lower = eligible_list | map('lower') | list %}
+  {% set current_lower = commander.name|lower %}
+  {% if eligible_list and (current_lower not in eligible_lower or exclusion.reason == 'secondary_face_only') %}
+    <div class="muted" style="font-size:12px; margin-top:.35rem; color:#facc15;" role="note">
+      {% if eligible_list|length == 1 %}
+        ⚠ This commander only works from '{{ eligible_list[0] }}'.
+        {% if exclusion.primary_face and exclusion.primary_face|lower != eligible_list[0]|lower %}
+          Front face '{{ exclusion.primary_face }}' can't lead a deck.
+        {% endif %}
+        We'll build using the supported face automatically.
+      {% else %}
+        ⚠ This commander only works from these faces: {{ eligible_list | join(', ') }}. We'll build using the supported faces automatically.
+      {% endif %}
+    </div>
+  {% endif %}
+{% endif %}
+
 <div>
   {% if tags and tags|length %}
   <div class="muted" style="font-size:12px; margin-bottom:.35rem;">Pick up to three themes. Toggle AND/OR to control how themes combine.</div>

code/web/templates/build/_step4.html

@@ -30,6 +30,10 @@
 					<input type="checkbox" name="prefer_owned" value="1" {% if prefer_owned %}checked{% endif %} onchange="this.form.requestSubmit();" />
 					Prefer owned cards (allow unowned fallback)
 				</label>
+				<label style="display:flex; align-items:center; gap:.35rem;" title="When enabled, modal DFC lands will replace a matching basic land as they are added so land counts stay level without manual trims.">
+					<input type="checkbox" name="swap_mdfc_basics" value="1" {% if swap_mdfc_basics %}checked{% endif %} onchange="this.form.requestSubmit();" />
+					Swap basics for MDFC lands
+				</label>
 				<a href="/owned" target="_blank" rel="noopener" class="btn">Manage Owned Library</a>
 			</form>
 			<div class="muted" style="font-size:12px; margin-top:-.25rem;">Tip: Locked cards are respected on reruns in Step 5.</div>

code/web/templates/build/_step5.html

@@ -74,9 +74,10 @@
       <p>Tags: {{ deck_theme_tags|default([])|join(', ') }}</p>
       <div style="margin:.35rem 0; color: var(--muted); display:flex; gap:.5rem; align-items:center; flex-wrap:wrap;">
         <span>Owned-only: <strong>{{ 'On' if owned_only else 'Off' }}</strong></span>
-          <div style="display:flex;align-items:center;gap:1rem;">
+          <div style="display:flex;align-items:center;gap:1rem;flex-wrap:wrap;">
             <button type="button" hx-get="/build/step4" hx-target="#wizard" hx-swap="innerHTML" style="background:#374151; color:#e5e7eb; border:none; border-radius:6px; padding:.25rem .5rem; cursor:pointer; font-size:12px;" title="Change owned settings in Review">Edit in Review</button>
             <div>Prefer-owned: <strong>{{ 'On' if prefer_owned else 'Off' }}</strong></div>
+            <div>MDFC swap: <strong>{{ 'On' if swap_mdfc_basics else 'Off' }}</strong></div>
           </div>
   <span style="margin-left:auto;"><a href="/owned" target="_blank" rel="noopener" class="btn">Manage Owned Library</a></span>
       </div>

code/web/templates/commanders/index.html

@@ -91,7 +91,7 @@
   .commander-list { display:flex; flex-direction:column; gap:1rem; margin-top:.5rem; }
 
   .commander-row { display:flex; gap:1rem; padding:1rem; border:1px solid var(--border); border-radius:14px; background:var(--panel); align-items:stretch; }
-  .commander-thumb { width:160px; flex:0 0 auto; }
+  .commander-thumb { width:160px; flex:0 0 auto; position:relative; }
   .commander-thumb img { width:160px; height:auto; border-radius:10px; border:1px solid var(--border); background:#0b0d12; display:block; }
   .commander-main { flex:1 1 auto; display:flex; flex-direction:column; gap:.6rem; min-width:0; }
   .commander-header { display:flex; flex-wrap:wrap; align-items:center; gap:.5rem .75rem; }

code/web/templates/commanders/row_wireframe.html

@@ -1,6 +1,7 @@
 {# Commander row partial fed by CommanderView entries #}
 {% from "partials/_macros.html" import color_identity %}
 {% set record = entry.record %}
+{% set display_label = record.name if '//' in record.name else record.display_name %}
 <article class="commander-row" data-commander-slug="{{ record.slug }}" data-hover-simple="true">
   <div class="commander-thumb">
     {% set small = record.image_small_url or record.image_normal_url %}
@@ -12,12 +13,13 @@
       loading="lazy"
       decoding="async"
       data-card-name="{{ record.display_name }}"
+      data-original-name="{{ record.name }}"
       data-hover-simple="true"
     />
   </div>
   <div class="commander-main">
     <div class="commander-header">
-      <h3 class="commander-name">{{ record.display_name }}</h3>
+      <h3 class="commander-name">{{ display_label }}</h3>
       {{ color_identity(record.color_identity, record.is_colorless, entry.color_aria_label, entry.color_label) }}
     </div>
     <p class="commander-context muted">{{ record.type_line or 'Legendary Creature' }}</p>

code/web/templates/diagnostics/index.html

@@ -12,6 +12,62 @@
       <button class="btn" id="diag-theme-reset">Reset theme preference</button>
     </div>
   </div>
+  <div class="card" style="background: var(--panel); border:1px solid var(--border); border-radius:10px; padding:.75rem; margin-bottom:.75rem">
+    <h3 style="margin-top:0">Multi-face merge snapshot</h3>
+    <div class="muted" style="margin-bottom:.35rem">Pulls from <code>logs/dfc_merge_summary.json</code> to verify merge coverage.</div>
+  {% set colors = merge_summary.get('colors') if merge_summary else {} %}
+    {% if colors %}
+    <div class="muted" style="margin-bottom:.35rem">Last updated: {{ merge_summary.updated_at or 'unknown' }}</div>
+    <div style="overflow-x:auto">
+      <table style="width:100%; border-collapse:collapse; font-size:13px;">
+        <thead>
+          <tr style="border-bottom:1px solid var(--border); text-align:left;">
+            <th style="padding:.35rem .25rem;">Color</th>
+            <th style="padding:.35rem .25rem;">Groups merged</th>
+            <th style="padding:.35rem .25rem;">Faces dropped</th>
+            <th style="padding:.35rem .25rem;">Multi-face rows</th>
+            <th style="padding:.35rem .25rem;">Latest entries</th>
+          </tr>
+        </thead>
+        <tbody>
+        {% for color, payload in colors.items()|dictsort %}
+          <tr style="border-bottom:1px solid rgba(148,163,184,0.2);">
+            <td style="padding:.35rem .25rem; font-weight:600;">{{ color|title }}</td>
+            <td style="padding:.35rem .25rem;">{{ payload.group_count or 0 }}</td>
+            <td style="padding:.35rem .25rem;">{{ payload.faces_dropped or 0 }}</td>
+            <td style="padding:.35rem .25rem;">{{ payload.multi_face_rows or 0 }}</td>
+            <td style="padding:.35rem .25rem;">
+              {% set entries = payload.entries or [] %}
+              {% if entries %}
+              <details>
+                <summary style="cursor:pointer;">{{ entries|length }} recorded</summary>
+                <ul style="margin:.35rem 0 0 .75rem; padding:0; list-style:disc; max-height:180px; overflow:auto;">
+                  {% for entry in entries %}
+                    {% if loop.index0 < 5 %}
+                    <li style="margin-bottom:.25rem;">
+                      <strong>{{ entry.name }}</strong> — {{ entry.total_faces }} faces (dropped {{ entry.dropped_faces }})
+                    </li>
+                    {% elif loop.index0 == 5 %}
+                    <li style="font-size:11px; opacity:.75;">… {{ entries|length - 5 }} more entries</li>
+                    {% break %}
+                    {% endif %}
+                  {% endfor %}
+                </ul>
+              </details>
+              {% else %}
+              <span class="muted">No groups recorded</span>
+              {% endif %}
+            </td>
+          </tr>
+        {% endfor %}
+        </tbody>
+      </table>
+    </div>
+    {% else %}
+    <div class="muted">No merge summary has been recorded. Run the tagger with multi-face merging enabled.</div>
+    {% endif %}
+    <div id="dfcMetrics" class="muted" style="margin-top:.5rem;">Loading MDFC metrics…</div>
+  </div>
   <div class="card" style="background: var(--panel); border:1px solid var(--border); border-radius:10px; padding:.75rem; margin-bottom:.75rem">
     <h3 style="margin-top:0">Performance (local)</h3>
     <div class="muted" style="margin-bottom:.35rem">Scroll the Step 5 list; this panel shows a rough FPS estimate and virtualization renders.</div>
@@ -193,6 +249,71 @@
       .catch(function(){ tokenEl.textContent = 'Theme stats unavailable'; });
   }
   loadTokenStats();
+  var dfcMetricsEl = document.getElementById('dfcMetrics');
+  function renderDfcMetrics(payload){
+    if (!dfcMetricsEl) return;
+    try {
+      if (!payload || payload.ok !== true) {
+        dfcMetricsEl.textContent = 'MDFC metrics unavailable';
+        return;
+      }
+      var metrics = payload.metrics || {};
+      var html = '';
+      html += '<div><strong>Deck summaries observed:</strong> ' + String(metrics.total_builds || 0) + '</div>';
+      var withDfc = Number(metrics.builds_with_mdfc || 0);
+      var share = metrics.build_share != null ? Number(metrics.build_share) : null;
+      if (!Number.isNaN(share) && share !== null) {
+        share = (share * 100).toFixed(1);
+      } else {
+        share = null;
+      }
+      html += '<div><strong>With MDFCs:</strong> ' + String(withDfc);
+      if (share !== null) {
+        html += ' (' + share + '%)';
+      }
+      html += '</div>';
+      var totalLands = Number(metrics.total_mdfc_lands || 0);
+      var avg = metrics.avg_mdfc_lands != null ? Number(metrics.avg_mdfc_lands) : null;
+      html += '<div><strong>Total MDFC lands:</strong> ' + String(totalLands);
+      if (avg !== null && !Number.isNaN(avg)) {
+        html += ' (avg ' + avg.toFixed(2) + ')';
+      }
+      html += '</div>';
+      var top = metrics.top_cards || {};
+      var topKeys = Object.keys(top);
+      if (topKeys.length) {
+        var items = topKeys.slice(0, 5).map(function(name){
+          return name + ' (' + String(top[name]) + ')';
+        });
+        html += '<div style="font-size:11px;">Top MDFC sources: ' + items.join(', ') + '</div>';
+      }
+      var last = metrics.last_summary || {};
+      if (typeof last.dfc_lands !== 'undefined') {
+        html += '<div style="font-size:11px; margin-top:0.25rem;">Last summary: ' + String(last.dfc_lands || 0) + ' MDFC lands · total with MDFCs ' + String(last.with_dfc || 0) + '</div>';
+      }
+      if (metrics.last_updated) {
+        html += '<div style="font-size:11px;">Updated: ' + String(metrics.last_updated) + '</div>';
+      }
+      dfcMetricsEl.innerHTML = html;
+    } catch (_){
+      dfcMetricsEl.textContent = 'MDFC metrics unavailable';
+    }
+  }
+  function loadDfcMetrics(){
+    if (!dfcMetricsEl) return;
+    dfcMetricsEl.textContent = 'Loading MDFC metrics…';
+    fetch('/status/dfc_metrics', { cache: 'no-store' })
+      .then(function(resp){
+        if (resp.status === 404) {
+          dfcMetricsEl.textContent = 'Diagnostics disabled (metrics unavailable)';
+          return null;
+        }
+        return resp.json();
+      })
+      .then(function(data){ if (data) renderDfcMetrics(data); })
+      .catch(function(){ dfcMetricsEl.textContent = 'MDFC metrics unavailable'; });
+  }
+  loadDfcMetrics();
   // Theme status and reset
   try{
     var tEl = document.getElementById('themeSummary');

code/web/templates/partials/deck_summary.html

@@ -29,6 +29,8 @@
       .stack-card:hover { z-index: 999; transform: translateY(-2px); box-shadow: 0 10px 22px rgba(0,0,0,.6); }
   .count-badge { position:absolute; top:6px; right:6px; background:rgba(17,24,39,.9); color:#e5e7eb; border:1px solid var(--border); border-radius:12px; font-size:12px; line-height:18px; height:18px; padding:0 6px; pointer-events:none; }
   .owned-badge { position:absolute; top:6px; left:6px; background:rgba(17,24,39,.9); color:#e5e7eb; border:1px solid var(--border); border-radius:12px; font-size:12px; line-height:18px; height:18px; min-width:18px; padding:0 6px; text-align:center; pointer-events:none; z-index: 2; }
+  .dfc-thumb-badge { position:absolute; bottom:8px; left:6px; background:rgba(15,23,42,.92); border:1px solid #34d399; color:#bbf7d0; border-radius:12px; font-size:11px; line-height:18px; height:18px; padding:0 6px; pointer-events:none; }
+  .dfc-thumb-badge.counts { border-color:#60a5fa; color:#bfdbfe; }
   .owned-flag { font-size:.95rem; opacity:.9; }
     </style>
     <div id="typeview-list" class="typeview">
@@ -47,8 +49,11 @@
             .list-row .count { font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; font-variant-numeric: tabular-nums; font-feature-settings: 'tnum'; text-align:right; color:#94a3b8; }
             .list-row .times { color:#94a3b8; text-align:center; font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; }
             .list-row .name { display:inline-block; padding: 2px 4px; border-radius: 6px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
-            .list-row .flip-slot { min-width:2.4em; display:flex; justify-content:center; align-items:center; }
+            .list-row .flip-slot { min-width:2.4em; display:flex; justify-content:flex-start; align-items:center; }
             .list-row .owned-flag { width: 1.6em; min-width: 1.6em; text-align:center; display:inline-block; }
+            .dfc-land-chip { display:inline-flex; align-items:center; gap:.25rem; padding:2px 6px; border-radius:999px; font-size:11px; font-weight:600; background:#0f172a; border:1px solid #334155; color:#e5e7eb; line-height:1; }
+            .dfc-land-chip.extra { border-color:#34d399; color:#a7f3d0; }
+            .dfc-land-chip.counts { border-color:#60a5fa; color:#bfdbfe; }
           </style>
           <div class="list-grid">
             {% for c in clist %}
@@ -69,7 +74,11 @@
                 <span class="count">{{ cnt }}</span>
                 <span class="times">x</span>
                 <span class="name dfc-anchor" title="{{ c.name }}" data-card-name="{{ c.name }}" data-count="{{ cnt }}" data-role="{{ c.role }}" data-tags="{{ (c.tags|map('trim')|join(', ')) if c.tags else '' }}"{% if overlaps %} data-overlaps="{{ overlaps|join(', ') }}"{% endif %}>{{ c.name }}</span>
-                <span class="flip-slot" aria-hidden="true"></span>
+                <span class="flip-slot" aria-hidden="true">
+                  {% if c.dfc_land %}
+                    <span class="dfc-land-chip {% if c.dfc_adds_extra_land %}extra{% else %}counts{% endif %}" title="{{ c.dfc_note or 'Modal double-faced land' }}">DFC land{% if c.dfc_adds_extra_land %} +1{% endif %}</span>
+                  {% endif %}
+                </span>
                 <span class="owned-flag" title="{{ 'Owned' if owned else 'Not owned' }}" aria-label="{{ 'Owned' if owned else 'Not owned' }}">{% if owned %}✔{% else %}✖{% endif %}</span>
               </div>
             {% endfor %}
@@ -106,6 +115,9 @@
                      sizes="(max-width: 1200px) 160px, 240px" />
                 <div class="count-badge">{{ cnt }}x</div>
                 <div class="owned-badge" title="{{ 'Owned' if owned else 'Not owned' }}" aria-label="{{ 'Owned' if owned else 'Not owned' }}">{% if owned %}✔{% else %}✖{% endif %}</div>
+                {% if c.dfc_land %}
+                  <div class="dfc-thumb-badge {% if c.dfc_adds_extra_land %}extra{% else %}counts{% endif %}" title="{{ c.dfc_note or 'Modal double-faced land' }}">DFC{% if c.dfc_adds_extra_land %}+1{% endif %}</div>
+                {% endif %}
               </div>
             {% endfor %}
             </div>
@@ -122,6 +134,60 @@
 
 <!-- Deck Summary initializer script moved below markup for proper element availability -->
 
+<!-- Land Summary -->
+{% set land = summary.land_summary if summary else None %}
+{% if land %}
+<section style="margin-top:1rem;">
+  <h5>Land Summary</h5>
+  <div class="muted" style="font-weight:600; margin-bottom:.35rem;">
+    {{ land.headline or ('Lands: ' ~ (land.traditional or 0)) }}
+  </div>
+  <div style="display:flex; flex-wrap:wrap; gap:.75rem; align-items:flex-start;">
+    <div class="muted">Traditional land slots: <strong>{{ land.traditional or 0 }}</strong></div>
+    <div class="muted">MDFC land additions: <strong>{{ land.dfc_lands or 0 }}</strong></div>
+    <div class="muted">Total with MDFCs: <strong>{{ land.with_dfc or land.traditional or 0 }}</strong></div>
+  </div>
+  {% if land.dfc_cards %}
+    <details style="margin-top:.5rem;">
+      <summary>MDFC mana sources ({{ land.dfc_cards|length }})</summary>
+      <ul style="list-style:none; padding:0; margin:.35rem 0 0; display:grid; gap:.35rem;">
+        {% for card in land.dfc_cards %}
+          {% set extra = card.adds_extra_land or card.counts_as_extra %}
+          {% set colors = card.colors or [] %}
+          <li class="muted" style="display:flex; gap:.5rem; flex-wrap:wrap; align-items:flex-start;">
+            <span class="chip"><span class="dot" style="background:#10b981;"></span> {{ card.name }} ×{{ card.count or 1 }}</span>
+            <span>Colors: {{ colors|join(', ') if colors else '–' }}</span>
+            {% if extra %}
+              <span class="chip" style="background:#0f172a; border-color:#34d399; color:#a7f3d0;">{{ card.note or 'Adds extra land slot' }}</span>
+            {% else %}
+              <span class="chip" style="background:#111827; border-color:#60a5fa; color:#bfdbfe;">{{ card.note or 'Counts as land slot' }}</span>
+            {% endif %}
+            {% if card.faces %}
+              <ul style="list-style:none; padding:0; margin:.2rem 0 0; display:grid; gap:.15rem; flex:1 0 100%;">
+                {% for face in card.faces %}
+                  {% set face_name = face.get('face') or face.get('faceName') or 'Face' %}
+                  {% set face_type = face.get('type') or '–' %}
+                  {% set mana_cost = face.get('mana_cost') %}
+                  {% set mana_value = face.get('mana_value') %}
+                  {% set produces = face.get('produces_mana') %}
+                  <li style="font-size:0.85rem; color:#e5e7eb; opacity:.85;">
+                    <span>{{ face_name }}</span>
+                    <span>— {{ face_type }}</span>
+                    {% if mana_cost %}<span>• Mana Cost: {{ mana_cost }}</span>{% endif %}
+                    {% if mana_value is not none %}<span>• MV: {{ mana_value }}</span>{% endif %}
+                    {% if produces %}<span>• Produces mana</span>{% endif %}
+                  </li>
+                {% endfor %}
+              </ul>
+            {% endif %}
+          </li>
+        {% endfor %}
+      </ul>
+    </details>
+  {% endif %}
+</section>
+{% endif %}
+
 <!-- Mana Overview Row: Pips • Sources • Curve -->
 <section style="margin-top:1rem;">
   <h5>Mana Overview</h5>
@@ -144,7 +210,11 @@
                 {% set c_cards = (pc[color] if pc and (color in pc) else []) %}
         {% set parts = [] %}
         {% for c in c_cards %}
-      {% set _ = parts.append(c.name ~ ((" ×" ~ c.count) if c.count and c.count>1 else '')) %}
+      {% set label = c.name ~ ((" ×" ~ c.count) if c.count and c.count>1 else '') %}
+      {% if c.dfc %}
+        {% set label = label ~ ' (DFC)' %}
+      {% endif %}
+      {% set _ = parts.append(label) %}
         {% endfor %}
         {% set cards_line = parts|join(' • ') %}
                 {% set pct_f = (pd.weights[color] * 100) if pd.weights and color in pd.weights else 0 %}