feat(mcp): audit recorder wrapper injecting via_mcp + mcp_token_id from ctx

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/mcp/audit_ctx.go

@@ -0,0 +1,45 @@
+package mcp
+
+import (
+	"context"
+
+	"github.com/yan1h/agent-coding-workflow/internal/audit"
+)
+
+type mcpTokenIDCtxKey struct{}
+
+func withMcpTokenID(ctx context.Context, tokenID string) context.Context {
+	return context.WithValue(ctx, mcpTokenIDCtxKey{}, tokenID)
+}
+
+func mcpTokenIDFromCtx(ctx context.Context) string {
+	if v, ok := ctx.Value(mcpTokenIDCtxKey{}).(string); ok {
+		return v
+	}
+	return ""
+}
+
+type wrappedRecorder struct {
+	inner audit.Recorder
+}
+
+// AuditWrap wraps an audit.Recorder so that every Record call automatically
+// injects "via_mcp" and "mcp_token_id" into the entry's Metadata when the
+// context carries an MCP token ID. Returns nil when inner is nil.
+func AuditWrap(inner audit.Recorder) audit.Recorder {
+	if inner == nil {
+		return nil
+	}
+	return &wrappedRecorder{inner: inner}
+}
+
+func (r *wrappedRecorder) Record(ctx context.Context, e audit.Entry) error {
+	if tid := mcpTokenIDFromCtx(ctx); tid != "" {
+		if e.Metadata == nil {
+			e.Metadata = map[string]any{}
+		}
+		e.Metadata["via_mcp"] = true
+		e.Metadata["mcp_token_id"] = tid
+	}
+	return r.inner.Record(ctx, e)
+}

internal/mcp/audit_ctx_test.go

@@ -0,0 +1,78 @@
+package mcp
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/yan1h/agent-coding-workflow/internal/audit"
+)
+
+type captureRec struct {
+	mu      sync.Mutex
+	entries []audit.Entry
+}
+
+func (r *captureRec) Record(_ context.Context, e audit.Entry) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	r.entries = append(r.entries, e)
+	return nil
+}
+
+func TestAuditWrap_InjectsTokenID(t *testing.T) {
+	t.Parallel()
+	cap := &captureRec{}
+	wrapped := AuditWrap(cap)
+
+	uid := uuid.New()
+	ctx := withMcpTokenID(context.Background(), "tok-123")
+	require.NoError(t, wrapped.Record(ctx, audit.Entry{
+		Action:   "issue.create",
+		UserID:   &uid,
+		Metadata: map[string]any{"slug": "demo"},
+	}))
+
+	require.Len(t, cap.entries, 1)
+	got := cap.entries[0]
+	assert.Equal(t, true, got.Metadata["via_mcp"])
+	assert.Equal(t, "tok-123", got.Metadata["mcp_token_id"])
+	assert.Equal(t, "demo", got.Metadata["slug"])
+}
+
+func TestAuditWrap_NoTokenID_Passthrough(t *testing.T) {
+	t.Parallel()
+	cap := &captureRec{}
+	wrapped := AuditWrap(cap)
+
+	require.NoError(t, wrapped.Record(context.Background(), audit.Entry{
+		Action: "user.login",
+	}))
+
+	require.Len(t, cap.entries, 1)
+	got := cap.entries[0]
+	_, hasViaMCP := got.Metadata["via_mcp"]
+	assert.False(t, hasViaMCP)
+}
+
+func TestAuditWrap_NilInner_ReturnsNil(t *testing.T) {
+	t.Parallel()
+	assert.Nil(t, AuditWrap(nil))
+}
+
+func TestAuditWrap_NilMetadata_Initialized(t *testing.T) {
+	t.Parallel()
+	cap := &captureRec{}
+	wrapped := AuditWrap(cap)
+
+	ctx := withMcpTokenID(context.Background(), "tok-x")
+	require.NoError(t, wrapped.Record(ctx, audit.Entry{Action: "x"}))
+
+	require.Len(t, cap.entries, 1)
+	require.NotNil(t, cap.entries[0].Metadata)
+	assert.Equal(t, "tok-x", cap.entries[0].Metadata["mcp_token_id"])
+}