Merge branch 'mai/knuth/phase-5c-itemwrite' (phase 5c slice C: MCP write tools validate)

mcp/tools.go

@@ -10,9 +10,27 @@ import (
 	"time"
 
 	"github.com/m/projax/internal/aggregate"
+	"github.com/m/projax/internal/itemwrite"
 	"github.com/m/projax/store"
 )
 
+// itemWriteError serialises an *itemwrite.ValidationError into a Go error
+// whose Error() string carries the JSON shape MCP clients can parse to
+// extract kind/path/detail. The JSON-RPC error envelope wraps this in
+// .error.data so a TypeScript client gets a typed object alongside the
+// human-readable message.
+func itemWriteError(ve *itemwrite.ValidationError) error {
+	body, err := json.Marshal(map[string]any{
+		"kind":   ve.Kind,
+		"path":   ve.Path,
+		"detail": ve.Detail,
+	})
+	if err != nil {
+		return ve
+	}
+	return fmt.Errorf("validation %s: %s [%s]", ve.Kind, ve.Detail, string(body))
+}
+
 // TimelineArgs is the MCP-facing input shape for the `timeline` tool — a
 // JSON-friendly equivalent of the URL query string web/timeline.go consumes.
 type TimelineArgs struct {
@@ -818,9 +836,6 @@ func createItemTool(st *store.Store) ToolHandler {
 		if err := parseInput(raw, &in); err != nil {
 			return nil, fmt.Errorf("bad params: %w", err)
 		}
-		if in.Slug == "" || in.Title == "" {
-			return nil, errors.New("slug and title are required")
-		}
 		parentIDs, err := resolveParentPaths(ctx, st, in.ParentPaths)
 		if err != nil {
 			return nil, err
@@ -829,6 +844,18 @@ func createItemTool(st *store.Store) ToolHandler {
 		if len(kind) == 0 {
 			kind = []string{"project"}
 		}
+		// Phase 5c: validate up-front so MCP clients get typed
+		// {kind, path, detail} on rejection instead of an opaque pgErr.
+		if ve := itemwrite.ValidateFormat(itemwrite.Input{
+			Title: in.Title, Slug: in.Slug, Status: in.Status, ParentIDs: parentIDs,
+		}); ve != nil {
+			return nil, itemWriteError(ve)
+		}
+		if ve := itemwrite.ValidateAgainstStore(ctx, st, itemwrite.Input{
+			Title: in.Title, Slug: in.Slug, Status: in.Status, ParentIDs: parentIDs,
+		}); ve != nil {
+			return nil, itemWriteError(ve)
+		}
 		it, err := st.Create(ctx, store.CreateInput{
 			Kind:       kind,
 			Title:      in.Title,
@@ -975,6 +1002,22 @@ func updateItemTool(st *store.Store) ToolHandler {
 			}
 			patch.ParentIDs = pids
 		}
+		// Phase 5c: pre-validate the patched item so MCP clients see typed
+		// {kind, path, detail} rejection instead of an opaque pgErr.
+		validateIn := itemwrite.Input{
+			ID:        it.ID,
+			Title:     patch.Title,
+			Slug:      patch.Slug,
+			Status:    patch.Status,
+			ParentIDs: patch.ParentIDs,
+			Path:      it.PrimaryPath(),
+		}
+		if ve := itemwrite.ValidateFormat(validateIn); ve != nil {
+			return nil, itemWriteError(ve)
+		}
+		if ve := itemwrite.ValidateAgainstStore(ctx, st, validateIn); ve != nil {
+			return nil, itemWriteError(ve)
+		}
 		updated, err := st.Update(ctx, it.ID, patch)
 		if err != nil {
 			return nil, err