Implement manifest model and local store

internal/app/status.go

@@ -2,10 +2,66 @@ package app
 
 import (
 	"context"
+	"flag"
+	"fmt"
 	"io"
+	"sort"
+
+	"gitea.maximumdirect.net/eric/narratio/internal/manifest"
 )
 
-// Status is a placeholder for future manifest status inspection behavior.
-func Status(_ context.Context, _ []string, out io.Writer) error {
-	return placeholder(out, "status")
+// Status reads and prints stage statuses from an existing manifest.
+func Status(ctx context.Context, args []string, out io.Writer) error {
+	fs := flag.NewFlagSet("status", flag.ContinueOnError)
+	fs.SetOutput(io.Discard)
+
+	var manifestPath string
+	fs.StringVar(&manifestPath, "manifest", "", "path to manifest.json")
+
+	if err := fs.Parse(args); err != nil {
+		return fmt.Errorf("status: invalid flags: %w", err)
+	}
+	if fs.NArg() != 0 {
+		return fmt.Errorf("status: unexpected positional arguments")
+	}
+	if manifestPath == "" {
+		return fmt.Errorf("status: --manifest is required")
+	}
+
+	store := &manifest.LocalStore{}
+	m, err := store.Load(ctx, manifestPath)
+	if err != nil {
+		return fmt.Errorf("status: %w", err)
+	}
+
+	if _, err := fmt.Fprintf(out, "session_id: %s\n", m.SessionID); err != nil {
+		return err
+	}
+	if _, err := fmt.Fprintf(out, "updated_at: %s\n", m.UpdatedAt.UTC().Format("2006-01-02T15:04:05Z07:00")); err != nil {
+		return err
+	}
+
+	if len(m.Stages) == 0 {
+		_, err := fmt.Fprintln(out, "stages: no stages recorded")
+		return err
+	}
+
+	if _, err := fmt.Fprintln(out, "stages:"); err != nil {
+		return err
+	}
+
+	names := make([]string, 0, len(m.Stages))
+	for name := range m.Stages {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+
+	for _, name := range names {
+		status := m.Stages[name].Status
+		if _, err := fmt.Fprintf(out, "- %s: %s\n", name, status); err != nil {
+			return err
+		}
+	}
+
+	return nil
 }