test(11-02): add group header and reassignment tests (GRP-02, GRP-03)

- TestPrintConfigGroupHeaders: verifies all group section headers in canonical order
- TestLoadGroupOverride: verifies [groups] TOML reassigns class group without changing Hz/waveform
- TestLoadGroupUnknownClass: verifies unknown class in [groups] produces warning not error
- TestPrintConfigGroupReassignment: verifies PrintConfig reflects reassigned group placement

config/config_test.go

@@ -600,6 +600,91 @@ func TestLoadResultConfigPath(t *testing.T) {
 	}
 }
 
+// --- Tests for Phase 11 Plan 02 (GRP-02, GRP-03) ---
+
+// TestPrintConfigGroupHeaders verifies GRP-02: group section headers appear in canonical order.
+func TestPrintConfigGroupHeaders(t *testing.T) {
+	t.Chdir(t.TempDir())
+	result, err := config.Load("")
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+
+	// Verify all populated group headers appear
+	expectedGroups := []string{"# Infrastructure", "# Web", "# Mail", "# Remote Access", "# File Transfer", "# Database", "# VoIP", "# Unknown"}
+	for _, header := range expectedGroups {
+		if !strings.Contains(output, header+"\n") {
+			t.Errorf("PrintConfig output missing group header %q", header)
+		}
+	}
+
+	// Verify canonical order: Infrastructure before Web before Mail etc.
+	infraIdx := strings.Index(output, "# Infrastructure\n")
+	webIdx := strings.Index(output, "# Web\n")
+	mailIdx := strings.Index(output, "# Mail\n")
+	remoteIdx := strings.Index(output, "# Remote Access\n")
+	ftIdx := strings.Index(output, "# File Transfer\n")
+	dbIdx := strings.Index(output, "# Database\n")
+	voipIdx := strings.Index(output, "# VoIP\n")
+	unknownIdx := strings.Index(output, "# Unknown\n")
+
+	if infraIdx >= webIdx || webIdx >= mailIdx || mailIdx >= remoteIdx ||
+		remoteIdx >= ftIdx || ftIdx >= dbIdx || dbIdx >= voipIdx || voipIdx >= unknownIdx {
+		t.Errorf("Group headers not in canonical order: infra=%d web=%d mail=%d remote=%d ft=%d db=%d voip=%d unknown=%d",
+			infraIdx, webIdx, mailIdx, remoteIdx, ftIdx, dbIdx, voipIdx, unknownIdx)
+	}
+}
+
+// TestLoadGroupOverride verifies GRP-03: [groups] reassigns a class to a different group.
+func TestLoadGroupOverride(t *testing.T) {
+	path := writeTOML(t, "[groups]\nIMAP = \"Web\"\n")
+	result, err := config.Load(path)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	cfg := result.FreqCfgs[classify.ClassIMAP]
+	if cfg.Group != "Web" {
+		t.Errorf("IMAP Group: got %q, want %q", cfg.Group, "Web")
+	}
+	// Frequency and waveform unchanged (D-08)
+	defaultCfg := synth.ClassFreqConfigs[classify.ClassIMAP]
+	if cfg.BaseHz != defaultCfg.BaseHz {
+		t.Errorf("IMAP BaseHz changed: got %v, want %v (should be unchanged by group reassignment)", cfg.BaseHz, defaultCfg.BaseHz)
+	}
+}
+
+// TestLoadGroupUnknownClass verifies D-09: unknown class in [groups] produces no error.
+func TestLoadGroupUnknownClass(t *testing.T) {
+	path := writeTOML(t, "[groups]\nBOGUS = \"Web\"\n")
+	result, err := config.Load(path)
+	if err != nil {
+		t.Fatalf("Load should not error on unknown [groups] class: %v", err)
+	}
+	// Should still have all default classes
+	if len(result.FreqCfgs) != len(classify.AllClasses()) {
+		t.Errorf("FreqCfgs len: got %d, want %d", len(result.FreqCfgs), len(classify.AllClasses()))
+	}
+}
+
+// TestPrintConfigGroupReassignment verifies PrintConfig reflects [groups] reassignment.
+func TestPrintConfigGroupReassignment(t *testing.T) {
+	path := writeTOML(t, "[groups]\nIMAP = \"Web\"\n")
+	result, err := config.Load(path)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+
+	// Find the "# Web" section and check IMAP appears after it
+	webIdx := strings.Index(output, "# Web\n")
+	mailIdx := strings.Index(output, "# Mail\n")
+	imapIdx := strings.Index(output, "[sounds.IMAP]")
+	if imapIdx < webIdx || imapIdx > mailIdx {
+		t.Errorf("IMAP (reassigned to Web) should appear between Web and Mail headers; web=%d imap=%d mail=%d", webIdx, imapIdx, mailIdx)
+	}
+}
+
 // TestLoadNoConfigReturnsLoadResult: Load("") in empty dir returns LoadResult with
 // len(FreqCfgs)==14, len(UserRules)==0, ConfigPath=="".
 func TestLoadNoConfigReturnsLoadResult(t *testing.T) {