feat: add 'bd where' command to show active beads location (bd-8x43)

Adds a new command that shows the active .beads directory path,
including redirect information for debugging. Supports --json output.

Example:
  bd where
  → /Users/stevey/gt/beads/mayor/rig/.beads
    (via redirect from /Users/stevey/gt/beads/crew/emma/.beads)
    prefix: bd
    database: /Users/stevey/gt/beads/mayor/rig/.beads/beads.db

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/where.go

@@ -0,0 +1,173 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/spf13/cobra"
+	"github.com/steveyegge/beads/internal/beads"
+	"github.com/steveyegge/beads/internal/utils"
+)
+
+// WhereResult contains information about the active beads location
+type WhereResult struct {
+	Path           string `json:"path"`                      // Active .beads directory path
+	RedirectedFrom string `json:"redirected_from,omitempty"` // Original path if redirected
+	Prefix         string `json:"prefix,omitempty"`          // Issue prefix (if detectable)
+	DatabasePath   string `json:"database_path,omitempty"`   // Full path to database file
+}
+
+var whereCmd = &cobra.Command{
+	Use:     "where",
+	GroupID: "setup",
+	Short:   "Show active beads location",
+	Long: `Show the active beads database location, including redirect information.
+
+This command is useful for debugging when using redirects, to understand
+which .beads directory is actually being used.
+
+Examples:
+  bd where           # Show active beads location
+  bd where --json    # Output in JSON format
+`,
+	Run: func(cmd *cobra.Command, args []string) {
+		result := WhereResult{}
+
+		// Find the beads directory (this follows redirects)
+		beadsDir := beads.FindBeadsDir()
+		if beadsDir == "" {
+			if jsonOutput {
+				outputJSON(map[string]string{"error": "no beads directory found"})
+			} else {
+				fmt.Fprintln(os.Stderr, "Error: no beads directory found")
+				fmt.Fprintln(os.Stderr, "Hint: run 'bd init' to create a database in the current directory")
+			}
+			os.Exit(1)
+		}
+
+		result.Path = beadsDir
+
+		// Check if we got here via redirect by looking for the original .beads directory
+		// Walk up from cwd to find any .beads with a redirect file
+		originalBeadsDir := findOriginalBeadsDir()
+		if originalBeadsDir != "" && originalBeadsDir != beadsDir {
+			result.RedirectedFrom = originalBeadsDir
+		}
+
+		// Find the database path
+		dbPath := beads.FindDatabasePath()
+		if dbPath != "" {
+			result.DatabasePath = dbPath
+
+			// Try to get the prefix from the database if we have a store
+			if store != nil {
+				ctx := rootCtx
+				if prefix, err := store.GetConfig(ctx, "issue_prefix"); err == nil && prefix != "" {
+					result.Prefix = prefix
+				}
+			}
+		}
+
+		// If we don't have the prefix from DB, try to detect it from JSONL
+		if result.Prefix == "" {
+			result.Prefix = detectPrefixFromDir(beadsDir)
+		}
+
+		// Output results
+		if jsonOutput {
+			outputJSON(result)
+		} else {
+			fmt.Println(result.Path)
+			if result.RedirectedFrom != "" {
+				fmt.Printf("  (via redirect from %s)\n", result.RedirectedFrom)
+			}
+			if result.Prefix != "" {
+				fmt.Printf("  prefix: %s\n", result.Prefix)
+			}
+			if result.DatabasePath != "" {
+				fmt.Printf("  database: %s\n", result.DatabasePath)
+			}
+		}
+	},
+}
+
+// findOriginalBeadsDir walks up from cwd looking for a .beads directory with a redirect file
+// Returns the original .beads path if found, empty string otherwise
+func findOriginalBeadsDir() string {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return ""
+	}
+
+	// Canonicalize cwd to handle symlinks
+	if resolved, err := filepath.EvalSymlinks(cwd); err == nil {
+		cwd = resolved
+	}
+
+	// Check BEADS_DIR first
+	if envDir := os.Getenv("BEADS_DIR"); envDir != "" {
+		envDir = utils.CanonicalizePath(envDir)
+		redirectFile := filepath.Join(envDir, beads.RedirectFileName)
+		if _, err := os.Stat(redirectFile); err == nil {
+			return envDir
+		}
+		return ""
+	}
+
+	// Walk up directory tree looking for .beads with redirect
+	for dir := cwd; dir != "/" && dir != "."; dir = filepath.Dir(dir) {
+		beadsDir := filepath.Join(dir, ".beads")
+		if info, err := os.Stat(beadsDir); err == nil && info.IsDir() {
+			redirectFile := filepath.Join(beadsDir, beads.RedirectFileName)
+			if _, err := os.Stat(redirectFile); err == nil {
+				return beadsDir
+			}
+			// Found .beads without redirect - this is the actual location
+			return ""
+		}
+	}
+
+	return ""
+}
+
+// detectPrefixFromDir tries to detect the issue prefix from files in the beads directory
+func detectPrefixFromDir(beadsDir string) string {
+	// Try to read from issues.jsonl and extract prefix from first issue ID
+	jsonlPath := filepath.Join(beadsDir, "issues.jsonl")
+	// #nosec G304 -- jsonlPath is constructed from trusted beadsDir
+	data, err := os.ReadFile(jsonlPath)
+	if err != nil {
+		return ""
+	}
+
+	// Find first line that looks like an issue
+	lines := strings.Split(string(data), "\n")
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+
+		// Quick JSON parse to get ID
+		var issue struct {
+			ID string `json:"id"`
+		}
+		if err := json.Unmarshal([]byte(line), &issue); err != nil {
+			continue
+		}
+
+		// Extract prefix from ID (e.g., "bd-123" -> "bd")
+		if idx := strings.LastIndex(issue.ID, "-"); idx > 0 {
+			return issue.ID[:idx]
+		}
+	}
+
+	return ""
+}
+
+func init() {
+	rootCmd.AddCommand(whereCmd)
+}