feat(microscope-slide-holder): explicit fit_clearance_slide behind the legacy material injection

microscope-slide-holder/libs/microscope-slide-hyperobject/slide.scad

@@ -1,17 +1,34 @@
 // ----------------------------------------------------
-// Material Hyperobject Compensations
-// (Passed dynamically by the Commons API)
+// Fit and scale compensation (explicit geometry inputs)
 // ----------------------------------------------------
-mat_shrinkage_x = 1.0;
-mat_shrinkage_y = 1.0;
-mat_shrinkage_z = 1.0;
+// scale_comp_x/y/z: unitless scale factors applied to the slide body
+// (1.0 = none). Manifest parameters of microscope-slide-hyperobject.
+scale_comp_x = 1.0;
+scale_comp_y = 1.0;
+scale_comp_z = 1.0;
+// fit_clearance_slide: extra slot clearance in mm that slide_slot_width()
+// adds for a sliding fit (0 = none). A library input: microscope-slide-holder
+// declares it; microscope-slide-hyperobject renders no slot, so it does not.
+fit_clearance_slide = 0.0;
 
-mat_clear_press = 0.0;
-mat_clear_slide = 0.0;
-mat_clear_loose = 0.0;
+// LEGACY material injection. REMOVE AT THE FLIP of the yantra4d flag
+// RENDER_MATERIAL_INJECTION (owner ruling "flag now, flip later").
+// While that flag is on, a render request naming target_material makes the
+// platform pass the material card's mat_shrinkage_x/y/z and mat_clear_slide
+// with -D. They are undef unless injected, and an injected value WINS over
+// the explicit parameter above, so a render with the flag on is unchanged.
+// At the flip, delete these four assignments and _legacy_or() and read the
+// explicit parameters directly. mat_clear_press and mat_clear_loose were
+// declared here but never read, so they are no longer declared.
+mat_shrinkage_x = undef;
+mat_shrinkage_y = undef;
+mat_shrinkage_z = undef;
+mat_clear_slide = undef;
+function _legacy_or(legacy, explicit) = is_undef(legacy) ? explicit : legacy;
 
 // Standard Microscope Slide Dimensions (ISO 8037)
-function slide_slot_width(thickness, tolerance) = thickness + tolerance + mat_clear_slide + 0.1;
+function slide_slot_width(thickness, tolerance) =
+  thickness + tolerance + _legacy_or(mat_clear_slide, fit_clearance_slide) + 0.1;
 function slide_pitch(slot_w, rib_w) = slot_w + rib_w;
 
 module slide_retention_rib(height, depth, root_w, tip_w, chamfer_h) {
@@ -87,8 +104,11 @@ render_mode = 0; // [0:main]
 if (render_mode == 0) {
   // Material simulation logic for transparency via OpenSCAD nightly alpha
   color([0.8, 0.9, 0.9, 0.4]) {
-    // Apply Material Hyperobject Shrinkage Compensation
-    scale([mat_shrinkage_x, mat_shrinkage_y, mat_shrinkage_z]) {
+    // Scale compensation: the explicit scale_comp_* parameters, or the legacy
+    // injected mat_shrinkage_* while the platform still injects them.
+    scale([_legacy_or(mat_shrinkage_x, scale_comp_x),
+           _legacy_or(mat_shrinkage_y, scale_comp_y),
+           _legacy_or(mat_shrinkage_z, scale_comp_z)]) {
       if (slide_standard == 0) {
         // ISO 8037-1 Primary
         iso_8037_slide(76.0, 26.0, 1.0);

microscope-slide-holder/project.json

@@ -565,6 +565,29 @@
         "es": "Holgura añadida al grosor de laminilla (ancho de ranura)"
       }
     },
+    {
+      "id": "fit_clearance_slide",
+      "type": "slider",
+      "default": 0.0,
+      "min": 0.0,
+      "max": 1.0,
+      "step": 0.01,
+      "group": "tolerance",
+      "visible_in_modes": ["box", "staining_rack", "cabinet_drawer"],
+      "visibility_level": "advanced",
+      "label": {
+        "en": "Extra slide-fit clearance (mm)",
+        "es": "Holgura extra de ajuste deslizante (mm)",
+        "fr": "Jeu supplémentaire d'ajustement glissant (mm)",
+        "pt": "Folga extra de ajuste deslizante (mm)"
+      },
+      "tooltip": {
+        "en": "Added to every slot width of the OpenSCAD box, staining rack and cabinet drawer (slot = slide thickness + Z tolerance + this + 0.1 mm). 0 adds nothing. The staining rack keeps a 5 mm minimum pitch, so there it only matters for thick slides. A caller that resolves a sliding-fit clearance elsewhere passes the number here.",
+        "es": "Se suma al ancho de cada ranura de la caja, el bastidor de tinción y el cajón de gabinete en OpenSCAD (ranura = grosor de laminilla + tolerancia Z + este valor + 0.1 mm). 0 no añade nada. El bastidor de tinción mantiene un paso mínimo de 5 mm, así que ahí solo influye con laminillas gruesas. Quien resuelve una holgura de ajuste deslizante en otro lugar pasa aquí el número.",
+        "fr": "S'ajoute à la largeur de chaque fente de la boîte, du portoir de coloration et du tiroir de cabinet OpenSCAD (fente = épaisseur de lame + tolérance Z + cette valeur + 0,1 mm). 0 n'ajoute rien. Le portoir de coloration garde un pas minimal de 5 mm : il n'y compte que pour les lames épaisses. Un appelant qui calcule ailleurs un jeu d'ajustement glissant transmet ici la valeur.",
+        "pt": "Somada à largura de cada ranhura da caixa, do suporte de coloração e da gaveta de gabinete em OpenSCAD (ranhura = espessura da lâmina + tolerância Z + este valor + 0,1 mm). 0 não acrescenta nada. O suporte de coloração mantém um passo mínimo de 5 mm, então ali só influi com lâminas grossas. Quem resolve uma folga de ajuste deslizante em outro lugar passa aqui o número."
+      }
+    },
     {
       "id": "density",
       "type": "select",