fix: add dispatch_context to schema docs and test buildDispatchMetadata

- Add dispatch_context column to requirements.md task schema section
- Export buildDispatchMetadata for test coverage
- Add tests: context forwarding, task_uuid overwrite protection, empty context

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/ai_client/client.go

@@ -196,6 +196,11 @@ func (d *Dispatcher) buildHistory(threadID string) ([]historyEntry, error) {
 	return history, nil
 }
 
+// ExportBuildDispatchMetadata exports buildDispatchMetadata for testing.
+func ExportBuildDispatchMetadata(task *database.Task) map[string]string {
+	return buildDispatchMetadata(task)
+}
+
 // buildDispatchMetadata constructs the metadata map for OpenClaw dispatch,
 // merging the task UUID with any DispatchContext from the rules pipeline.
 func buildDispatchMetadata(task *database.Task) map[string]string {

internal/ai_client/client_test.go

@@ -12,6 +12,53 @@ import (
 	"thuanle.me/claw-email-bridge/internal/database"
 )
 
+func TestBuildDispatchMetadata_ForwardsContext(t *testing.T) {
+	task := &database.Task{
+		TaskUUID:         "uuid-ctx-test",
+		DispatchContext:  `{"rule":"whitelist","source":"env"}`,
+	}
+	metadata := ai_client.ExportBuildDispatchMetadata(task)
+
+	if metadata["task_uuid"] != "uuid-ctx-test" {
+		t.Errorf("expected task_uuid=uuid-ctx-test, got %q", metadata["task_uuid"])
+	}
+	if metadata["rule"] != "whitelist" {
+		t.Errorf("expected rule=whitelist, got %q", metadata["rule"])
+	}
+	if metadata["source"] != "env" {
+		t.Errorf("expected source=env, got %q", metadata["source"])
+	}
+}
+
+func TestBuildDispatchMetadata_ProtectsTaskUUID(t *testing.T) {
+	task := &database.Task{
+		TaskUUID:        "original-uuid",
+		DispatchContext: `{"task_uuid":"malicious-override","extra":"data"}`,
+	}
+	metadata := ai_client.ExportBuildDispatchMetadata(task)
+
+	if metadata["task_uuid"] != "original-uuid" {
+		t.Errorf("task_uuid should not be overwritten, got %q", metadata["task_uuid"])
+	}
+	if metadata["extra"] != "data" {
+		t.Errorf("expected extra=data, got %q", metadata["extra"])
+	}
+}
+
+func TestBuildDispatchMetadata_NoContext(t *testing.T) {
+	task := &database.Task{
+		TaskUUID: "uuid-no-ctx",
+	}
+	metadata := ai_client.ExportBuildDispatchMetadata(task)
+
+	if len(metadata) != 1 {
+		t.Errorf("expected 1 key, got %d", len(metadata))
+	}
+	if metadata["task_uuid"] != "uuid-no-ctx" {
+		t.Errorf("expected task_uuid=uuid-no-ctx, got %q", metadata["task_uuid"])
+	}
+}
+
 // Test matrix #2: OpenClaw fail 2 lần, lần 3 thành công → COMPLETED, attempt_openclaw = 3.
 func TestDispatch_RetryThenSuccess(t *testing.T) {
 	tdb := database.NewTestDB(t)