diff --git a/cmd/notioncrawl/main.go b/cmd/notioncrawl/main.go
index 1d41014..7b46c98 100644
--- a/cmd/notioncrawl/main.go
+++ b/cmd/notioncrawl/main.go
@@ -1,15 +1,352 @@
 package main
 
 import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"flag"
 	"fmt"
+	"io"
 	"os"
+	"strings"
+
+	"github.com/vincentkoc/notioncrawl/internal/config"
+	"github.com/vincentkoc/notioncrawl/internal/markdown"
+	"github.com/vincentkoc/notioncrawl/internal/notionapi"
+	"github.com/vincentkoc/notioncrawl/internal/notiondesktop"
+	"github.com/vincentkoc/notioncrawl/internal/share"
+	"github.com/vincentkoc/notioncrawl/internal/store"
 )
 
 func main() {
-	if len(os.Args) > 1 && (os.Args[1] == "-h" || os.Args[1] == "--help") {
-		fmt.Print("Usage of notioncrawl:\n  notioncrawl [global flags] <command> [args]\n")
-		return
+	if err := run(context.Background(), os.Args[1:], os.Stdout, os.Stderr); err != nil {
+		fmt.Fprintln(os.Stderr, "notioncrawl:", err)
+		os.Exit(1)
 	}
-	fmt.Fprintln(os.Stderr, "notioncrawl: implementation in progress")
-	os.Exit(2)
+}
+
+func run(ctx context.Context, args []string, stdout, stderr io.Writer) error {
+	global := flag.NewFlagSet("notioncrawl", flag.ContinueOnError)
+	global.SetOutput(stderr)
+	configPath := global.String("config", "", "config file path")
+	dbPath := global.String("db", "", "database path override")
+	if err := global.Parse(args); err != nil {
+		return err
+	}
+	rest := global.Args()
+	if len(rest) == 0 || rest[0] == "help" || rest[0] == "--help" || rest[0] == "-h" {
+		printHelp(stdout)
+		return nil
+	}
+	cmd := rest[0]
+	cmdArgs := rest[1:]
+	if cmd == "init" {
+		path, err := config.WriteStarter(*configPath)
+		if err != nil {
+			return err
+		}
+		fmt.Fprintf(stdout, "wrote %s\n", path)
+		return nil
+	}
+	cfg, err := config.Load(*configPath)
+	if err != nil {
+		return err
+	}
+	if *dbPath != "" {
+		cfg.DBPath, err = config.ExpandPath(*dbPath)
+		if err != nil {
+			return err
+		}
+	}
+	switch cmd {
+	case "doctor":
+		return runDoctor(ctx, stdout, cfg)
+	case "sync":
+		return runSync(ctx, stdout, cfg, cmdArgs)
+	case "export-md":
+		return runExportMarkdown(ctx, stdout, cfg)
+	case "search":
+		return runSearch(ctx, stdout, cfg, cmdArgs)
+	case "sql":
+		return runSQL(ctx, stdout, cfg, cmdArgs)
+	case "publish":
+		return runPublish(ctx, stdout, cfg, cmdArgs)
+	case "subscribe":
+		return runSubscribe(ctx, stdout, cfg, cmdArgs)
+	case "update":
+		return runUpdate(ctx, stdout, cfg, cmdArgs)
+	default:
+		return fmt.Errorf("unknown command %q", cmd)
+	}
+}
+
+func runDoctor(ctx context.Context, stdout io.Writer, cfg config.Config) error {
+	st, err := store.Open(cfg.DBPath)
+	if err != nil {
+		return err
+	}
+	defer st.Close()
+	desktop, err := notiondesktop.Inspect(cfg.Notion.Desktop.Path)
+	if err != nil {
+		return err
+	}
+	report := map[string]any{
+		"db_path":           cfg.DBPath,
+		"cache_dir":         cfg.CacheDir,
+		"markdown_dir":      cfg.MarkdownDir,
+		"desktop_path":      desktop.Path,
+		"desktop_available": desktop.Available,
+		"desktop_size":      desktop.SizeBytes,
+		"api_token_env":     cfg.Notion.API.TokenEnv,
+		"api_token_present": cfg.APIToken() != "",
+	}
+	_ = ctx
+	b, err := json.MarshalIndent(report, "", "  ")
+	if err != nil {
+		return err
+	}
+	fmt.Fprintln(stdout, string(b))
+	return nil
+}
+
+func runSync(ctx context.Context, stdout io.Writer, cfg config.Config, args []string) error {
+	fs := flag.NewFlagSet("sync", flag.ContinueOnError)
+	source := fs.String("source", "all", "source: desktop, api, all")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	st, err := store.Open(cfg.DBPath)
+	if err != nil {
+		return err
+	}
+	defer st.Close()
+	switch *source {
+	case "desktop":
+		s, err := notiondesktop.Ingest(ctx, st, cfg.Notion.Desktop.Path, cfg.CacheDir)
+		if err != nil {
+			return err
+		}
+		fmt.Fprintf(stdout, "desktop: pages=%d blocks=%d collections=%d comments=%d snapshot=%s\n", s.Pages, s.Blocks, s.Collections, s.Comments, s.Source.Snapshot)
+	case "api":
+		s, err := notionapi.Client{
+			BaseURL: cfg.Notion.API.BaseURL,
+			Version: cfg.Notion.API.Version,
+			Token:   cfg.APIToken(),
+		}.Sync(ctx, st)
+		if err != nil {
+			return err
+		}
+		fmt.Fprintf(stdout, "api: users=%d pages=%d blocks=%d comments=%d\n", s.Users, s.Pages, s.Blocks, s.Comments)
+	case "all":
+		if cfg.Notion.Desktop.Enabled {
+			s, err := notiondesktop.Ingest(ctx, st, cfg.Notion.Desktop.Path, cfg.CacheDir)
+			if err != nil {
+				return err
+			}
+			fmt.Fprintf(stdout, "desktop: pages=%d blocks=%d collections=%d comments=%d snapshot=%s\n", s.Pages, s.Blocks, s.Collections, s.Comments, s.Source.Snapshot)
+		}
+		if cfg.Notion.API.Enabled && cfg.APIToken() != "" {
+			s, err := notionapi.Client{
+				BaseURL: cfg.Notion.API.BaseURL,
+				Version: cfg.Notion.API.Version,
+				Token:   cfg.APIToken(),
+			}.Sync(ctx, st)
+			if err != nil {
+				return err
+			}
+			fmt.Fprintf(stdout, "api: users=%d pages=%d blocks=%d comments=%d\n", s.Users, s.Pages, s.Blocks, s.Comments)
+		}
+	default:
+		return fmt.Errorf("unknown source %q", *source)
+	}
+	return nil
+}
+
+func runExportMarkdown(ctx context.Context, stdout io.Writer, cfg config.Config) error {
+	st, err := store.Open(cfg.DBPath)
+	if err != nil {
+		return err
+	}
+	defer st.Close()
+	s, err := markdown.Exporter{Store: st, Dir: cfg.MarkdownDir}.Export(ctx)
+	if err != nil {
+		return err
+	}
+	fmt.Fprintf(stdout, "exported %d pages to %s\n", s.Pages, cfg.MarkdownDir)
+	return nil
+}
+
+func runSearch(ctx context.Context, stdout io.Writer, cfg config.Config, args []string) error {
+	if len(args) == 0 {
+		return fmt.Errorf("search query required")
+	}
+	st, err := store.Open(cfg.DBPath)
+	if err != nil {
+		return err
+	}
+	defer st.Close()
+	results, err := st.Search(ctx, strings.Join(args, " "), 20)
+	if err != nil {
+		return err
+	}
+	for _, r := range results {
+		fmt.Fprintf(stdout, "%s\t%s\t%s\t%s\n", r.Kind, r.ID, r.Title, r.Text)
+	}
+	return nil
+}
+
+func runSQL(ctx context.Context, stdout io.Writer, cfg config.Config, args []string) error {
+	if len(args) == 0 {
+		return fmt.Errorf("sql query required")
+	}
+	query := strings.TrimSpace(strings.Join(args, " "))
+	if !isReadOnlyQuery(query) {
+		return fmt.Errorf("only read-only select/with/pragma queries are allowed")
+	}
+	st, err := store.Open(cfg.DBPath)
+	if err != nil {
+		return err
+	}
+	defer st.Close()
+	rows, err := st.DB().QueryContext(ctx, query)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+	return printRows(stdout, rows)
+}
+
+func runPublish(ctx context.Context, stdout io.Writer, cfg config.Config, args []string) error {
+	fs := flag.NewFlagSet("publish", flag.ContinueOnError)
+	remote := fs.String("remote", cfg.Share.Remote, "git remote")
+	repo := fs.String("repo", cfg.Share.RepoPath, "share repo path")
+	branch := fs.String("branch", cfg.Share.Branch, "share branch")
+	message := fs.String("message", "archive: notioncrawl snapshot", "commit message")
+	push := fs.Bool("push", false, "push after commit")
+	noCommit := fs.Bool("no-commit", false, "write snapshot without committing")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	st, err := store.Open(cfg.DBPath)
+	if err != nil {
+		return err
+	}
+	defer st.Close()
+	if _, err := (markdown.Exporter{Store: st, Dir: cfg.MarkdownDir}).Export(ctx); err != nil {
+		return err
+	}
+	s, err := share.Publish(ctx, st, share.PublishOptions{
+		RepoPath: *repo, Remote: *remote, Branch: *branch, MarkdownDir: cfg.MarkdownDir,
+		Message: *message, Push: *push, Commit: !*noCommit,
+	})
+	if err != nil {
+		return err
+	}
+	fmt.Fprintf(stdout, "published %d tables to %s committed=%t pushed=%t\n", len(s.Manifest.Tables), *repo, s.Committed, s.Pushed)
+	return nil
+}
+
+func runSubscribe(ctx context.Context, stdout io.Writer, cfg config.Config, args []string) error {
+	fs := flag.NewFlagSet("subscribe", flag.ContinueOnError)
+	repo := fs.String("repo", cfg.Share.RepoPath, "share repo path")
+	branch := fs.String("branch", cfg.Share.Branch, "share branch")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	remote := cfg.Share.Remote
+	if fs.NArg() > 0 {
+		remote = fs.Arg(0)
+	}
+	st, err := store.Open(cfg.DBPath)
+	if err != nil {
+		return err
+	}
+	defer st.Close()
+	manifest, err := share.Subscribe(ctx, st, remote, *repo, *branch)
+	if err != nil {
+		return err
+	}
+	fmt.Fprintf(stdout, "subscribed %s tables=%d generated_at=%s\n", remote, len(manifest.Tables), manifest.GeneratedAt)
+	return nil
+}
+
+func runUpdate(ctx context.Context, stdout io.Writer, cfg config.Config, args []string) error {
+	fs := flag.NewFlagSet("update", flag.ContinueOnError)
+	repo := fs.String("repo", cfg.Share.RepoPath, "share repo path")
+	branch := fs.String("branch", cfg.Share.Branch, "share branch")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	st, err := store.Open(cfg.DBPath)
+	if err != nil {
+		return err
+	}
+	defer st.Close()
+	manifest, err := share.Update(ctx, st, *repo, *branch)
+	if err != nil {
+		return err
+	}
+	fmt.Fprintf(stdout, "updated tables=%d generated_at=%s\n", len(manifest.Tables), manifest.GeneratedAt)
+	return nil
+}
+
+func printRows(w io.Writer, rows *sql.Rows) error {
+	cols, err := rows.Columns()
+	if err != nil {
+		return err
+	}
+	fmt.Fprintln(w, strings.Join(cols, "\t"))
+	for rows.Next() {
+		values := make([]any, len(cols))
+		ptrs := make([]any, len(cols))
+		for i := range values {
+			ptrs[i] = &values[i]
+		}
+		if err := rows.Scan(ptrs...); err != nil {
+			return err
+		}
+		for i, value := range values {
+			if i > 0 {
+				fmt.Fprint(w, "\t")
+			}
+			switch x := value.(type) {
+			case nil:
+				fmt.Fprint(w, "")
+			case []byte:
+				fmt.Fprint(w, string(x))
+			default:
+				fmt.Fprint(w, x)
+			}
+		}
+		fmt.Fprintln(w)
+	}
+	return rows.Err()
+}
+
+func isReadOnlyQuery(query string) bool {
+	lower := strings.ToLower(strings.TrimSpace(query))
+	return strings.HasPrefix(lower, "select ") || strings.HasPrefix(lower, "with ") || strings.HasPrefix(lower, "pragma ")
+}
+
+func printHelp(w io.Writer) {
+	fmt.Fprint(w, `Usage of notioncrawl:
+  notioncrawl [global flags] <command> [args]
+
+Global flags:
+  --config PATH   config file path
+  --db PATH       database path override
+
+Commands:
+  init                      Write a starter config
+  doctor                    Check config, database, desktop cache, and token
+  sync --source desktop     Ingest Notion Desktop cache
+  sync --source api         Ingest through the official Notion API
+  sync --source all         Run enabled sources
+  export-md                 Render normalized Markdown from SQLite
+  search QUERY              Search page text
+  sql QUERY                 Run read-only SQL
+  publish [--push]          Export data and Markdown into a git share repo
+  subscribe REMOTE          Clone/import a git share repo
+  update                    Pull/import a git share repo
+`)
 }