Refine branch differentiation comment and add hash verification tests

pkg/analysis/topology/topology.go

@@ -277,7 +277,7 @@ func GenerateFuzzyHash(t *FunctionTopology) string {
 	}
 	brBucket := 0
 	if t.BranchCount > 0 {
-		// FIX: Differentiate between 0 branches (linear) and 1 branch (single if).
+		// Differentiate between 0 branches (linear) and 1 branch (single if).
 		// Log2(1) is 0, so we shift by 1 to make BR0 mean "no branches" and BR1 mean "1 branch".
 		brBucket = int(math.Log2(float64(t.BranchCount))) + 1
 	}

pkg/analysis/topology/topology_test.go

@@ -188,11 +188,38 @@ func TestFuzzyHashDistinction(t *testing.T) {
 		}
 	}`
 
+	srcBranched2 := `package main
+	func branched2(b bool, c bool) {
+		if b {
+			println("branch 1")
+		}
+		if c {
+			println("branch 2")
+		}
+	}`
+
 	fnLinear := testutil.CompileAndGetFunction(t, srcLinear, "linear")
 	fnBranched := testutil.CompileAndGetFunction(t, srcBranched, "branched")
+	fnBranched2 := testutil.CompileAndGetFunction(t, srcBranched2, "branched2")
 
 	topoLinear := topology.ExtractTopology(fnLinear)
 	topoBranched := topology.ExtractTopology(fnBranched)
+	topoBranched2 := topology.ExtractTopology(fnBranched2)
+
+	// Linear: 0 branches -> BR0
+	if !strings.Contains(topoLinear.FuzzyHash, "BR0") {
+		t.Errorf("Linear code hash should contain BR0, got %q", topoLinear.FuzzyHash)
+	}
+
+	// Single If: 1 branch -> BR1
+	if !strings.Contains(topoBranched.FuzzyHash, "BR1") {
+		t.Errorf("Branched code (1 if) hash should contain BR1, got %q", topoBranched.FuzzyHash)
+	}
+
+	// Two Ifs: 2 branches -> BR2
+	if !strings.Contains(topoBranched2.FuzzyHash, "BR2") {
+		t.Errorf("Branched code (2 ifs) hash should contain BR2, got %q", topoBranched2.FuzzyHash)
+	}
 
 	if topoLinear.FuzzyHash == topoBranched.FuzzyHash {
 		t.Errorf("Fuzzy Hash Collision: Linear and Branched code produced same hash %q", topoLinear.FuzzyHash)