fix: navigation parity — GetFunctionAt explicit-platform + InstructionTextLine address

Handle/BNBasicBlock.cs

@@ -802,7 +802,9 @@ ref length
 				    break;
 			    }
 
-			    yield return new InstructionTextLine(tokens);
+			    // Carry the instruction's start address on the line, mirroring Python's
+			    // Function.instructions / BinaryView.instructions which yield (tokens, addr).
+			    yield return new InstructionTextLine(tokens, address);
 			    address += length;
 		    }
 

NavigationExtensions.cs

@@ -529,8 +529,7 @@ private static void VerifyDerivedStringLayout()
                 return null;
             }
 
-            // Match the requested platform (or the view default) first, then fall back to the
-            // first candidate, exactly as Python does.
+            // Match the requested platform (or the view default) first.
             Platform? resolved = platform;
             if (null == resolved)
             {
@@ -545,7 +544,18 @@ private static void VerifyDerivedStringLayout()
                 }
             }
 
-            return candidates[0];
+            // Implicit-platform lookups fall back to the first candidate, exactly as Python does
+            // when plat is None (get_function_at falls back to funcs[0]). An explicit platform
+            // with no match returns null: Python's plat-is-not-None branch is a strict
+            // BNGetAnalysisFunction(view, plat, addr) lookup that returns None when no function on
+            // that platform sits at the address -- it must NOT silently return a different
+            // platform's function.
+            if (null == platform)
+            {
+                return candidates[0];
+            }
+
+            return null;
         }
 
         /// <summary>

Struct/BNInstructionTextLine.cs

@@ -20,18 +20,30 @@ internal unsafe struct BNInstructionTextLine
 		public ulong count;
 	}
 
-    public sealed class InstructionTextLine 
+    public sealed class InstructionTextLine
     {
 		public InstructionTextToken[] Tokens { get; } = Array.Empty<InstructionTextToken>();
-
-		public InstructionTextLine() 
+
+		// The virtual address of the first byte of the instruction this line disassembles. Python's
+		// Function.instructions / BinaryView.instructions generators yield (tokens, addr) per
+		// instruction; this field carries that address so consumers do not lose it. It is 0 when the
+		// line was not produced by an address-walking generator (e.g. synthesized token lists).
+		public ulong Address { get; } = 0;
+
+		public InstructionTextLine()
 		{
-			
+
 		}
-		
-		public InstructionTextLine(InstructionTextToken[] tokens) 
+
+		public InstructionTextLine(InstructionTextToken[] tokens)
 		{
-		    this.Tokens = tokens;
+			this.Tokens = tokens;
+		}
+
+		public InstructionTextLine(InstructionTextToken[] tokens, ulong address)
+		{
+			this.Tokens = tokens;
+			this.Address = address;
 		}
 
 		public override string ToString()
@@ -42,7 +54,7 @@ public override string ToString()
 			{
 				builder.Append(token.Text);
 			}
-			
+
 			return builder.ToString();
 		}
     }