feat(channel): 跨平台 IM 接入抽象契约（UnifiedMessage/PlatformAdapter/Capabilities/Actor 身份）

internal/channel/adapter/capabilities_test.go

@@ -0,0 +1,52 @@
+package adapter
+
+import "testing"
+
+func TestCapabilitiesNormalizeFillsZeroNumerics(t *testing.T) {
+	t.Parallel()
+
+	caps := Capabilities{Image: true, Proactive: true}.Normalize()
+
+	if caps.MaxMessageLength != defaultMaxMessageLength {
+		t.Errorf("MaxMessageLength = %d, want %d", caps.MaxMessageLength, defaultMaxMessageLength)
+	}
+	if caps.RecommendBurstMax != defaultRecommendBurstMax {
+		t.Errorf("RecommendBurstMax = %d, want %d", caps.RecommendBurstMax, defaultRecommendBurstMax)
+	}
+	// Boolean fields must be preserved, not overwritten by normalization.
+	if !caps.Image || !caps.Proactive {
+		t.Errorf("booleans changed by Normalize: %+v", caps)
+	}
+}
+
+func TestCapabilitiesNormalizePreservesExplicit(t *testing.T) {
+	t.Parallel()
+
+	caps := Capabilities{MaxMessageLength: 100, RecommendBurstMax: 5}.Normalize()
+
+	if caps.MaxMessageLength != 100 {
+		t.Errorf("MaxMessageLength = %d, want 100 (explicit preserved)", caps.MaxMessageLength)
+	}
+	if caps.RecommendBurstMax != 5 {
+		t.Errorf("RecommendBurstMax = %d, want 5 (explicit preserved)", caps.RecommendBurstMax)
+	}
+}
+
+func TestDefaultCapabilities(t *testing.T) {
+	t.Parallel()
+
+	caps := DefaultCapabilities()
+
+	if caps.MaxMessageLength != defaultMaxMessageLength {
+		t.Errorf("MaxMessageLength = %d, want %d", caps.MaxMessageLength, defaultMaxMessageLength)
+	}
+	if !caps.Markdown || !caps.Image {
+		t.Errorf("expected markdown+image by default, got %+v", caps)
+	}
+	if caps.Voice || caps.Reaction || caps.TypingHint || caps.Proactive {
+		t.Errorf("expected rich/proactive features off by default, got %+v", caps)
+	}
+	if caps.RecommendBurstMax != defaultRecommendBurstMax {
+		t.Errorf("RecommendBurstMax = %d, want %d", caps.RecommendBurstMax, defaultRecommendBurstMax)
+	}
+}