diff --git a/config/PhysiCell_settings.xml b/config/PhysiCell_settings.xml
index e3cd03b4a..6f41e17ac 100644
--- a/config/PhysiCell_settings.xml
+++ b/config/PhysiCell_settings.xml
@@ -35,6 +35,18 @@
         <SVG>
             <interval units="min">60</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/modules/PhysiCell_pathology.cpp b/modules/PhysiCell_pathology.cpp
index eef368b1e..f0fc66112 100644
--- a/modules/PhysiCell_pathology.cpp
+++ b/modules/PhysiCell_pathology.cpp
@@ -1707,42 +1707,198 @@ std::string paint_by_density_percentage(double concentration, double max_conc, d
 	return colormap[ind];
 }
 
+// Returns true if the string is a valid SVG/CSS color:
+//   - CSS named color (case-insensitive)
+//   - #rgb or #rrggbb hex notation
+//   - rgb(r,g,b) functional notation (integers 0-255)
+static bool is_valid_svg_color( const std::string& s )
+{
+	if( s.empty() ) return false;
+
+	// #rgb / #rrggbb
+	if( s[0] == '#' )
+	{
+		if( s.size() != 4 && s.size() != 7 ) return false;
+		for( size_t i = 1; i < s.size(); i++ )
+		{
+			char c = s[i];
+			if( !( (c>='0'&&c<='9') || (c>='a'&&c<='f') || (c>='A'&&c<='F') ) )
+				return false;
+		}
+		return true;
+	}
+
+	// rgb(r,g,b) — accept optional whitespace, integers 0-255
+	if( s.size() > 4 && s.substr(0,4) == "rgb(" && s.back() == ')' )
+	{
+		std::string inner = s.substr(4, s.size()-5);
+		// parse three comma-separated integers
+		int vals[3]; int nread;
+		char extra;
+		nread = std::sscanf(inner.c_str(), " %d , %d , %d %c", &vals[0], &vals[1], &vals[2], &extra);
+		if( nread != 3 ) return false;
+		for( int i = 0; i < 3; i++ )
+			if( vals[i] < 0 || vals[i] > 255 ) return false;
+		return true;
+	}
+
+	// CSS named colors (standard 147 + rebeccapurple)
+	static const std::unordered_set<std::string> named = {
+		"aliceblue","antiquewhite","aqua","aquamarine","azure","beige","bisque","black",
+		"blanchedalmond","blue","blueviolet","brown","burlywood","cadetblue","chartreuse",
+		"chocolate","coral","cornflowerblue","cornsilk","crimson","cyan","darkblue","darkcyan",
+		"darkgoldenrod","darkgray","darkgreen","darkgrey","darkkhaki","darkmagenta",
+		"darkolivegreen","darkorange","darkorchid","darkred","darksalmon","darkseagreen",
+		"darkslateblue","darkslategray","darkslategrey","darkturquoise","darkviolet","deeppink",
+		"deepskyblue","dimgray","dimgrey","dodgerblue","firebrick","floralwhite","forestgreen",
+		"fuchsia","gainsboro","ghostwhite","gold","goldenrod","gray","green","greenyellow",
+		"grey","honeydew","hotpink","indianred","indigo","ivory","khaki","lavender",
+		"lavenderblush","lawngreen","lemonchiffon","lightblue","lightcoral","lightcyan",
+		"lightgoldenrodyellow","lightgray","lightgreen","lightgrey","lightpink","lightsalmon",
+		"lightseagreen","lightskyblue","lightslategray","lightslategrey","lightsteelblue",
+		"lightyellow","lime","limegreen","linen","magenta","maroon","mediumaquamarine",
+		"mediumblue","mediumorchid","mediumpurple","mediumseagreen","mediumslateblue",
+		"mediumspringgreen","mediumturquoise","mediumvioletred","midnightblue","mintcream",
+		"mistyrose","moccasin","navajowhite","navy","oldlace","olive","olivedrab","orange",
+		"orangered","orchid","palegoldenrod","palegreen","paleturquoise","palevioletred",
+		"papayawhip","peachpuff","peru","pink","plum","powderblue","purple","rebeccapurple",
+		"red","rosybrown","royalblue","saddlebrown","salmon","sandybrown","seagreen",
+		"seashell","sienna","silver","skyblue","slateblue","slategray","slategrey","snow",
+		"springgreen","steelblue","tan","teal","thistle","tomato","turquoise","violet",
+		"wheat","white","whitesmoke","yellow","yellowgreen"
+	};
+	// compare lower-case
+	std::string lower = s;
+	std::transform(lower.begin(), lower.end(), lower.begin(), ::tolower);
+	return named.count(lower) > 0;
+}
+
+// Convert HSV (h in [0,360), s and v in [0,1]) to an SVG "rgb(r,g,b)" string.
+static std::string hsv_to_svg_color( double h, double s, double v )
+{
+	double c = v * s;
+	double x = c * ( 1.0 - std::fabs( std::fmod( h / 60.0, 2.0 ) - 1.0 ) );
+	double m = v - c;
+	double r1, g1, b1;
+	if     ( h <  60 ) { r1 = c; g1 = x; b1 = 0; }
+	else if( h < 120 ) { r1 = x; g1 = c; b1 = 0; }
+	else if( h < 180 ) { r1 = 0; g1 = c; b1 = x; }
+	else if( h < 240 ) { r1 = 0; g1 = x; b1 = c; }
+	else if( h < 300 ) { r1 = x; g1 = 0; b1 = c; }
+	else               { r1 = c; g1 = 0; b1 = x; }
+	int r = (int)std::round( (r1 + m) * 255 );
+	int g = (int)std::round( (g1 + m) * 255 );
+	int b = (int)std::round( (b1 + m) * 255 );
+	return "rgb(" + std::to_string(r) + "," + std::to_string(g) + "," + std::to_string(b) + ")";
+}
+
 std::vector<std::string> paint_by_number_cell_coloring( Cell* pCell )
 {
-	static std::vector< std::string > colors(0); 
-	static bool setup_done = false; 
+	static std::vector<std::string> colors;
+	static bool setup_done = false;
 	if( setup_done == false )
 	{
-		colors.push_back( "grey" ); // default color will be grey 
+		// Built-in palette for the first 13 cell types.
+		static const std::vector<std::string> builtin = {
+			"grey", "red", "yellow", "green", "blue",
+			"magenta", "orange", "lime", "cyan",
+			"hotpink", "peachpuff", "darkseagreen", "lightskyblue"
+		};
+				int n = (int)cell_definitions_by_index.size();
+
+		if( PhysiCell_settings.svg_cell_colors_specified )
+		{
+			// Validate: every user-supplied name must match a cell definition.
+			for( auto& kv : PhysiCell_settings.svg_cell_colors_by_name )
+			{
+				if( cell_definitions_by_name.find(kv.first) == cell_definitions_by_name.end() )
+				{
+					std::cerr << "ERROR (paint_by_number_cell_coloring): <cell_color name=\""
+					          << kv.first << "\"> does not match any cell definition." << std::endl;
+					exit(-1);
+				}
+			}
+			// Validate: every supplied color value must be a recognized SVG color.
+			for( auto& kv : PhysiCell_settings.svg_cell_colors_by_name )
+			{
+				if( !is_valid_svg_color(kv.second) )
+				{
+					std::cerr << "ERROR (paint_by_number_cell_coloring): <cell_color name=\""
+					          << kv.first << "\"> has unrecognized color value \""
+					          << kv.second << "\"." << std::endl;
+					exit(-1);
+				}
+			}
+			// Build the pool of default colors not already claimed by the user (case-insensitive).
+			std::unordered_set<std::string> claimed;
+			for( auto& kv : PhysiCell_settings.svg_cell_colors_by_name )
+			{
+				std::string lc = kv.second;
+				std::transform(lc.begin(), lc.end(), lc.begin(), ::tolower);
+				claimed.insert(lc);
+			}
+			std::vector<std::string> pool;
+			for( auto& c : builtin )
+			{
+				if( claimed.count(c) == 0 )
+				{ pool.push_back(c); }
+			}
 
-		colors.push_back( "red" );
-		colors.push_back( "yellow" ); 	
-		colors.push_back( "green" ); 	
-		colors.push_back( "blue" ); 
-		
-		colors.push_back( "magenta" ); 	
-		colors.push_back( "orange" ); 	
-		colors.push_back( "lime" ); 	
-		colors.push_back( "cyan" );
-		
-		colors.push_back( "hotpink" ); 	
-		colors.push_back( "peachpuff" ); 	
-		colors.push_back( "darkseagreen" ); 	
-		colors.push_back( "lightskyblue" );
+			// Assign colors: user-specified first, then pool, then HSV-generated.
+			colors.resize(n);
+			int pool_idx = 0;
+			int extra_idx = 0;
+			for( int i = 0; i < n; i++ )
+			{
+				const std::string& name = cell_definitions_by_index[i]->name;
+				auto it = PhysiCell_settings.svg_cell_colors_by_name.find(name);
+				if( it != PhysiCell_settings.svg_cell_colors_by_name.end() )
+				{
+					colors[i] = it->second;
+				}
+				else if( pool_idx < (int)pool.size() )
+				{
+					colors[i] = pool[pool_idx++];
+				}
+				else
+				{
+					double hue = std::fmod( extra_idx * 137.508, 360.0 );
+					colors[i] = hsv_to_svg_color( hue, 0.65, 0.85 );
+					extra_idx++;
+				}
+			}
+		}
+		else
+		{
+			// No user colors: use built-in palette; generate via golden-angle HSV for extras.
+			colors.resize(n);
+			int n_extra = 0;
+			for( int i = 0; i < n; i++ )
+			{
+				if( i < (int)builtin.size() )
+				{ colors[i] = builtin[i]; }
+				else
+				{
+					double hue = std::fmod( n_extra * 137.508, 360.0 );
+					colors[i] = hsv_to_svg_color( hue, 0.65, 0.85 );
+					n_extra++;
+				}
+			}
+		}
 
-		setup_done = true; 
+		setup_done = true;
 	}
-	
-	// start all black 
-	
-	std::vector<std::string> output = { "black", "black", "black", "black" }; 
-	
-	// paint by number -- by cell type 
-	
-	std::string interior_color = "white"; 
-	if( pCell->type < 13 )
+
+	// start all black
+
+	std::vector<std::string> output = { "black", "black", "black", "black" };
+
+	// paint by number -- by cell type
+
+	std::string interior_color = "white";
+	if( pCell->type >= 0 && pCell->type < (int)colors.size() )
 	{ interior_color = colors[ pCell->type ]; }
-	
+
 	output[0] = interior_color; // set cytoplasm color 
 	
 	/*
diff --git a/modules/PhysiCell_pathology.h b/modules/PhysiCell_pathology.h
index fae47f212..6390572a2 100644
--- a/modules/PhysiCell_pathology.h
+++ b/modules/PhysiCell_pathology.h
@@ -65,8 +65,12 @@
 ###############################################################################
 */
 
-#include <vector>
+
+#include <algorithm>
+ #include <cctype>
 #include <string>
+#include <unordered_set>
+#include <vector>
 
 #ifndef __PhysiCell_pathology__
 #define __PhysiCell_pathology__
diff --git a/modules/PhysiCell_settings.cpp b/modules/PhysiCell_settings.cpp
index c741835b7..db54acbf3 100644
--- a/modules/PhysiCell_settings.cpp
+++ b/modules/PhysiCell_settings.cpp
@@ -213,9 +213,22 @@ void PhysiCell_Settings::read_from_pugixml( void )
 	enable_full_saves = xml_get_bool_value( node , "enable" ); 
 	node = node.parent(); 
 	
-	node = xml_find_node( node , "SVG" ); 
+	node = xml_find_node( node , "SVG" );
 	SVG_save_interval = xml_get_double_value( node , "interval" );
-	enable_SVG_saves = xml_get_bool_value( node , "enable" ); 
+	enable_SVG_saves = xml_get_bool_value( node , "enable" );
+
+	pugi::xml_node node_cell_colors = node.child("cell_colors");
+	if( node_cell_colors )
+	{
+		svg_cell_colors_specified = true;
+		for( pugi::xml_node cc = node_cell_colors.child("cell_color"); cc; cc = cc.next_sibling("cell_color") )
+		{
+			std::string cname = cc.attribute("name").as_string();
+			std::string color  = cc.child_value();
+			if( !cname.empty() && !color.empty() )
+			{ svg_cell_colors_by_name[cname] = color; }
+		}
+	}
 
 	pugi::xml_node node_plot_substrate; 
 	node_plot_substrate = xml_find_node( node , "plot_substrate" );
diff --git a/modules/PhysiCell_settings.h b/modules/PhysiCell_settings.h
index b1bd30d80..2397cb94b 100644
--- a/modules/PhysiCell_settings.h
+++ b/modules/PhysiCell_settings.h
@@ -75,6 +75,7 @@
 #include <vector>
 #include <random>
 #include <chrono>
+#include <map>
 #include <unordered_map>
 #include <getopt.h>
 
@@ -98,26 +99,29 @@ class PhysiCell_Settings
  private:
  public:
 	// overall 
-	double max_time = 60*24*45;   
+	double max_time = 60*24*45;
 
 	// units
-	std::string time_units = "min"; 
-	std::string space_units = "micron"; 
+	std::string time_units = "min";
+	std::string space_units = "micron";
  
 	// parallel options 
-	int omp_num_threads = 2; 
+	int omp_num_threads = 2;
 	
 	// save options
-	std::string folder = "."; 
+	std::string folder = ".";
 
-	double full_save_interval = 60;  
-	bool enable_full_saves = true; 
-	bool enable_legacy_saves = false; 
+	double full_save_interval = 60;
+	bool enable_full_saves = true;
+	bool enable_legacy_saves = false;
 
-	bool disable_automated_spring_adhesions = false; 
+	bool disable_automated_spring_adhesions = false;
 	
-	double SVG_save_interval = 60; 
-	bool enable_SVG_saves = true; 
+	double SVG_save_interval = 60;
+	bool enable_SVG_saves = true;
+
+	bool svg_cell_colors_specified = false;
+	std::map<std::string, std::string> svg_cell_colors_by_name;
 
 	bool enable_substrate_plot = false;
 	std::string substrate_to_monitor = "oxygen"; 
diff --git a/sample_projects/asymmetric_division/config/PhysiCell_settings.xml b/sample_projects/asymmetric_division/config/PhysiCell_settings.xml
index 994749fe0..e6de749be 100644
--- a/sample_projects/asymmetric_division/config/PhysiCell_settings.xml
+++ b/sample_projects/asymmetric_division/config/PhysiCell_settings.xml
@@ -41,6 +41,18 @@
                 <min_conc>0</min_conc>
                 <max_conc>1</max_conc>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/biorobots/config/PhysiCell_settings.xml b/sample_projects/biorobots/config/PhysiCell_settings.xml
index e005c6f71..161d9063a 100644
--- a/sample_projects/biorobots/config/PhysiCell_settings.xml
+++ b/sample_projects/biorobots/config/PhysiCell_settings.xml
@@ -50,6 +50,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/cancer_biorobots/config/PhysiCell_settings.xml b/sample_projects/cancer_biorobots/config/PhysiCell_settings.xml
index fd9e9221a..1f42b308e 100644
--- a/sample_projects/cancer_biorobots/config/PhysiCell_settings.xml
+++ b/sample_projects/cancer_biorobots/config/PhysiCell_settings.xml
@@ -50,6 +50,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/custom_division/config/PhysiCell_settings.xml b/sample_projects/custom_division/config/PhysiCell_settings.xml
index c05d6a672..5114401df 100644
--- a/sample_projects/custom_division/config/PhysiCell_settings.xml
+++ b/sample_projects/custom_division/config/PhysiCell_settings.xml
@@ -40,6 +40,18 @@
                 <min_conc />
                 <max_conc />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/dirichlet_from_file/config/PhysiCell_settings.xml b/sample_projects/dirichlet_from_file/config/PhysiCell_settings.xml
index 1aa7aff2a..7b6cab934 100644
--- a/sample_projects/dirichlet_from_file/config/PhysiCell_settings.xml
+++ b/sample_projects/dirichlet_from_file/config/PhysiCell_settings.xml
@@ -41,6 +41,18 @@
                 <min_conc>0</min_conc>
                 <max_conc>1</max_conc>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/episode/config/PhysiCell_settings.xml b/sample_projects/episode/config/PhysiCell_settings.xml
index 68ff43e83..1df354f50 100644
--- a/sample_projects/episode/config/PhysiCell_settings.xml
+++ b/sample_projects/episode/config/PhysiCell_settings.xml
@@ -41,6 +41,18 @@
                 <min_conc>0</min_conc>
                 <max_conc>1</max_conc>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/extended_asym_div/config/PhysiCell_settings.xml b/sample_projects/extended_asym_div/config/PhysiCell_settings.xml
index 92067fd67..ef0e9a0ad 100644
--- a/sample_projects/extended_asym_div/config/PhysiCell_settings.xml
+++ b/sample_projects/extended_asym_div/config/PhysiCell_settings.xml
@@ -41,6 +41,18 @@
                 <min_conc>0</min_conc>
                 <max_conc>1</max_conc>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/heterogeneity/config/PhysiCell_settings.xml b/sample_projects/heterogeneity/config/PhysiCell_settings.xml
index 2cefeefa9..d32adda41 100644
--- a/sample_projects/heterogeneity/config/PhysiCell_settings.xml
+++ b/sample_projects/heterogeneity/config/PhysiCell_settings.xml
@@ -50,6 +50,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/immune_function/config/PhysiCell_settings.xml b/sample_projects/immune_function/config/PhysiCell_settings.xml
index bfd1cdc3d..2ac2ed224 100644
--- a/sample_projects/immune_function/config/PhysiCell_settings.xml
+++ b/sample_projects/immune_function/config/PhysiCell_settings.xml
@@ -35,6 +35,18 @@
         <SVG>
             <interval units="min">1</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/interactions/config/PhysiCell_settings.xml b/sample_projects/interactions/config/PhysiCell_settings.xml
index c702bb526..6b5674b7c 100644
--- a/sample_projects/interactions/config/PhysiCell_settings.xml
+++ b/sample_projects/interactions/config/PhysiCell_settings.xml
@@ -50,6 +50,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/mechano/config/PhysiCell_settings.xml b/sample_projects/mechano/config/PhysiCell_settings.xml
index 2faf3f248..f2cea3673 100644
--- a/sample_projects/mechano/config/PhysiCell_settings.xml
+++ b/sample_projects/mechano/config/PhysiCell_settings.xml
@@ -50,6 +50,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/physimess/config/PhysiCell_settings.xml b/sample_projects/physimess/config/PhysiCell_settings.xml
index eb02d2bee..88fcf5c64 100644
--- a/sample_projects/physimess/config/PhysiCell_settings.xml
+++ b/sample_projects/physimess/config/PhysiCell_settings.xml
@@ -50,6 +50,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/rules_sample/config/PhysiCell_settings.xml b/sample_projects/rules_sample/config/PhysiCell_settings.xml
index 79972ef99..4e0137dad 100644
--- a/sample_projects/rules_sample/config/PhysiCell_settings.xml
+++ b/sample_projects/rules_sample/config/PhysiCell_settings.xml
@@ -41,6 +41,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/template/config/PhysiCell_settings.xml b/sample_projects/template/config/PhysiCell_settings.xml
index ff88a4a5c..23dfa284a 100644
--- a/sample_projects/template/config/PhysiCell_settings.xml
+++ b/sample_projects/template/config/PhysiCell_settings.xml
@@ -41,6 +41,18 @@
                 <min_conc>0</min_conc>
                 <max_conc>1</max_conc>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/template_xml_rules_extended/config/PhysiCell_settings.xml b/sample_projects/template_xml_rules_extended/config/PhysiCell_settings.xml
index 661e345c4..d728dae0e 100644
--- a/sample_projects/template_xml_rules_extended/config/PhysiCell_settings.xml
+++ b/sample_projects/template_xml_rules_extended/config/PhysiCell_settings.xml
@@ -41,6 +41,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/virus_macrophage/config/PhysiCell_settings.xml b/sample_projects/virus_macrophage/config/PhysiCell_settings.xml
index 5e3be1a7c..1ccff4ec9 100644
--- a/sample_projects/virus_macrophage/config/PhysiCell_settings.xml
+++ b/sample_projects/virus_macrophage/config/PhysiCell_settings.xml
@@ -50,6 +50,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects/worm/config/PhysiCell_settings.xml b/sample_projects/worm/config/PhysiCell_settings.xml
index 1c7ced5f9..4be12c6de 100644
--- a/sample_projects/worm/config/PhysiCell_settings.xml
+++ b/sample_projects/worm/config/PhysiCell_settings.xml
@@ -50,6 +50,18 @@
                 <max_conc />
                 <colormap />
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings.xml b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings.xml
index 37077adb0..a2f5906d1 100644
--- a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings.xml
+++ b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings.xml
@@ -45,6 +45,18 @@
                 <max_conc>1.0</max_conc>
                 <colormap>viridis</colormap>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D.xml b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D.xml
index 37077adb0..a2f5906d1 100644
--- a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D.xml
+++ b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D.xml
@@ -45,6 +45,18 @@
                 <max_conc>1.0</max_conc>
                 <colormap>viridis</colormap>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_cluster_migration.xml b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_cluster_migration.xml
index adbf23a8c..36de1b23a 100644
--- a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_cluster_migration.xml
+++ b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_cluster_migration.xml
@@ -44,6 +44,18 @@
                 <min_conc>0.0</min_conc>
                 <max_conc>1.0</max_conc>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_single_cell_migration.xml b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_single_cell_migration.xml
index ffb7a390d..e372fe698 100644
--- a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_single_cell_migration.xml
+++ b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_single_cell_migration.xml
@@ -45,6 +45,18 @@
                 <max_conc>1.0</max_conc>
                 <colormap>viridis</colormap>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_trail_migration.xml b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_trail_migration.xml
index 37077adb0..a2f5906d1 100644
--- a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_trail_migration.xml
+++ b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_2D_trail_migration.xml
@@ -45,6 +45,18 @@
                 <max_conc>1.0</max_conc>
                 <colormap>viridis</colormap>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_3D.xml b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_3D.xml
index 5daf2ad0b..fca8c638d 100644
--- a/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_3D.xml
+++ b/sample_projects_intracellular/boolean/cancer_invasion/config/PhysiCell_settings_3D.xml
@@ -45,6 +45,18 @@
                 <max_conc>1.0</max_conc>
                 <colormap>viridis</colormap>
             </plot_substrate>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>
diff --git a/sample_projects_intracellular/boolean/physiboss_cell_lines/config/PhysiCell_settings.xml b/sample_projects_intracellular/boolean/physiboss_cell_lines/config/PhysiCell_settings.xml
index b41a3fc53..fd6b23667 100644
--- a/sample_projects_intracellular/boolean/physiboss_cell_lines/config/PhysiCell_settings.xml
+++ b/sample_projects_intracellular/boolean/physiboss_cell_lines/config/PhysiCell_settings.xml
@@ -35,6 +35,18 @@
         <SVG>
             <interval units="min">10</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>true</enable>
diff --git a/sample_projects_physipkpd/combo/config/pkpd_model.xml b/sample_projects_physipkpd/combo/config/pkpd_model.xml
index e27cd9294..f61969c26 100644
--- a/sample_projects_physipkpd/combo/config/pkpd_model.xml
+++ b/sample_projects_physipkpd/combo/config/pkpd_model.xml
@@ -37,6 +37,18 @@
         <SVG>
             <interval units="min">15</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
 
         <legacy_data>
diff --git a/sample_projects_physipkpd/confluence_start-deprecated/config/pkpd_model.xml b/sample_projects_physipkpd/confluence_start-deprecated/config/pkpd_model.xml
index a6e305dc9..bb3e57d1a 100644
--- a/sample_projects_physipkpd/confluence_start-deprecated/config/pkpd_model.xml
+++ b/sample_projects_physipkpd/confluence_start-deprecated/config/pkpd_model.xml
@@ -37,6 +37,18 @@
         <SVG>
             <interval units="min">15</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
 
         <legacy_data>
@@ -248,4 +260,3 @@
     </user_parameters>
     
 </PhysiCell_settings>
-
diff --git a/sample_projects_physipkpd/moa_apoptosis/config/pkpd_model.xml b/sample_projects_physipkpd/moa_apoptosis/config/pkpd_model.xml
index 766d4e1fc..28d65a704 100644
--- a/sample_projects_physipkpd/moa_apoptosis/config/pkpd_model.xml
+++ b/sample_projects_physipkpd/moa_apoptosis/config/pkpd_model.xml
@@ -37,6 +37,18 @@
         <SVG>
             <interval units="min">15</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
 
         <legacy_data>
diff --git a/sample_projects_physipkpd/moa_motility/config/pkpd_model.xml b/sample_projects_physipkpd/moa_motility/config/pkpd_model.xml
index 9d0cf40ac..3a393033a 100644
--- a/sample_projects_physipkpd/moa_motility/config/pkpd_model.xml
+++ b/sample_projects_physipkpd/moa_motility/config/pkpd_model.xml
@@ -37,6 +37,18 @@
         <SVG>
             <interval units="min">15</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
 
         <legacy_data>
diff --git a/sample_projects_physipkpd/moa_necrosis/config/pkpd_model.xml b/sample_projects_physipkpd/moa_necrosis/config/pkpd_model.xml
index a41fbab28..c1f59f984 100644
--- a/sample_projects_physipkpd/moa_necrosis/config/pkpd_model.xml
+++ b/sample_projects_physipkpd/moa_necrosis/config/pkpd_model.xml
@@ -37,6 +37,18 @@
         <SVG>
             <interval units="min">15</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
 
         <legacy_data>
diff --git a/sample_projects_physipkpd/moa_proliferation/config/pkpd_model.xml b/sample_projects_physipkpd/moa_proliferation/config/pkpd_model.xml
index 24ca6d420..c1f33ac6a 100644
--- a/sample_projects_physipkpd/moa_proliferation/config/pkpd_model.xml
+++ b/sample_projects_physipkpd/moa_proliferation/config/pkpd_model.xml
@@ -37,6 +37,18 @@
         <SVG>
             <interval units="min">15</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
 
         <legacy_data>
@@ -238,4 +250,3 @@
     </user_parameters>
     
 </PhysiCell_settings>
-
diff --git a/sample_projects_physipkpd/template_pkpd/config/pkpd_model.xml b/sample_projects_physipkpd/template_pkpd/config/pkpd_model.xml
index d130a8d4f..5e88ccc30 100644
--- a/sample_projects_physipkpd/template_pkpd/config/pkpd_model.xml
+++ b/sample_projects_physipkpd/template_pkpd/config/pkpd_model.xml
@@ -37,6 +37,18 @@
         <SVG>
             <interval units="min">15</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
 
         <legacy_data>
diff --git a/unit_tests/custom_DCs_2substrates/config/PhysiCell_settings.xml b/unit_tests/custom_DCs_2substrates/config/PhysiCell_settings.xml
index f1e35bbbd..2fe86e80d 100644
--- a/unit_tests/custom_DCs_2substrates/config/PhysiCell_settings.xml
+++ b/unit_tests/custom_DCs_2substrates/config/PhysiCell_settings.xml
@@ -35,6 +35,18 @@
         <SVG>
             <interval units="min">1</interval>
             <enable>true</enable>
+            <!-- Optional: override SVG colors for specific cell types.
+                 Names must match cell_definition names exactly; an unrecognized name is an error.
+                 Partial coverage is fine: unlisted cell types are assigned colors automatically
+                 from the built-in palette (with any user-claimed colors skipped), then generated
+                 via golden-angle HSV spacing once the palette is exhausted.
+                 If this element is absent entirely, all colors are assigned automatically.
+                 Accepted color formats: CSS named colors (e.g. "red"), #rrggbb/#rgb hex, rgb(r,g,b).
+            <cell_colors>
+                <cell_color name="cancer cell">red</cell_color>
+                <cell_color name="immune cell">cyan</cell_color>
+            </cell_colors>
+            -->
         </SVG>
         <legacy_data>
             <enable>false</enable>