Add issue-prefix as a config.yaml option

Allow setting issue prefix via config.yaml that works independently
of --no-db mode. This provides a consistent way to set the prefix
across the entire repository.

Precedence order:
1. --prefix flag (highest)
2. issue-prefix in config.yaml
3. .beads/nodb_prefix.txt (no-db mode only)
4. Auto-detect from directory name (lowest)

Changes:
- Add issue-prefix to config defaults in internal/config/config.go
- Update cmd/bd/init.go to read from config before auto-detecting
- Update cmd/bd/nodb.go detectPrefix to check config.yaml
- Update .beads/config.yaml with documentation and example

Usage:
  # .beads/config.yaml
  issue-prefix: "myproject"

  # Or via environment variable
  BD_ISSUE_PREFIX=myproject bd init

This makes the prefix setting repository-scoped and automatically
respected by bd init in both normal and no-db modes.

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

.beads/config.yaml

@@ -3,6 +3,11 @@
 # All settings can also be set via environment variables (BD_* prefix)
 # or overridden with command-line flags
 
+# Issue prefix for this repository (used by bd init)
+# If not set, bd init will auto-detect from directory name
+# Example: issue-prefix: "myproject" creates issues like "myproject-1", "myproject-2", etc.
+# issue-prefix: ""
+
 # Use no-db mode: load from JSONL, no SQLite, write back after each command
 # When true, bd will use .beads/issues.jsonl as the source of truth
 # instead of SQLite database

cmd/bd/init.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/fatih/color"
 	"github.com/spf13/cobra"
+	"github.com/steveyegge/beads/internal/config"
 	"github.com/steveyegge/beads/internal/storage/sqlite"
 )
 
@@ -24,6 +25,12 @@ With --no-db: creates .beads/ directory and nodb_prefix.txt file instead of SQLi
 		prefix, _ := cmd.Flags().GetString("prefix")
 		quiet, _ := cmd.Flags().GetBool("quiet")
 
+		// Initialize config (PersistentPreRun doesn't run for init command)
+		if err := config.Initialize(); err != nil {
+			fmt.Fprintf(os.Stderr, "Warning: failed to initialize config: %v\n", err)
+			// Non-fatal - continue with defaults
+		}
+
 		// Check BEADS_DB environment variable if --db flag not set
 		// (PersistentPreRun doesn't run for init command)
 		if dbPath == "" {
@@ -32,6 +39,12 @@ With --no-db: creates .beads/ directory and nodb_prefix.txt file instead of SQLi
 			}
 		}
 
+		// Determine prefix with precedence: flag > config > auto-detect
+		if prefix == "" {
+			// Try to get from config file
+			prefix = config.GetString("issue-prefix")
+		}
+
 		if prefix == "" {
 			// Auto-detect from directory name
 			cwd, err := os.Getwd()

cmd/bd/nodb.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/steveyegge/beads/internal/config"
 	"github.com/steveyegge/beads/internal/storage/memory"
 	"github.com/steveyegge/beads/internal/types"
 )
@@ -111,8 +112,9 @@ func loadIssuesFromJSONL(path string) ([]*types.Issue, error) {
 // detectPrefix detects the issue prefix to use in --no-db mode
 // Priority:
 // 1. .beads/nodb_prefix.txt file (if exists)
-// 2. Common prefix from existing issues (if all share same prefix)
-// 3. Current directory name (fallback)
+// 2. issue-prefix from config.yaml (if set)
+// 3. Common prefix from existing issues (if all share same prefix)
+// 4. Current directory name (fallback)
 func detectPrefix(beadsDir string, memStore *memory.MemoryStorage) (string, error) {
 	// Check for nodb_prefix.txt
 	prefixFile := filepath.Join(beadsDir, "nodb_prefix.txt")
@@ -123,6 +125,12 @@ func detectPrefix(beadsDir string, memStore *memory.MemoryStorage) (string, erro
 		}
 	}
 
+	// Check config.yaml for issue-prefix
+	configPrefix := config.GetString("issue-prefix")
+	if configPrefix != "" {
+		return configPrefix, nil
+	}
+
 	// Check existing issues for common prefix
 	issues := memStore.GetAllIssues()
 	if len(issues) > 0 {

internal/config/config.go

@@ -74,6 +74,7 @@ func Initialize() error {
 	v.SetDefault("no-db", false)
 	v.SetDefault("db", "")
 	v.SetDefault("actor", "")
+	v.SetDefault("issue-prefix", "")
 	
 	// Additional environment variables (not prefixed with BD_)
 	// These are bound explicitly for backward compatibility