feat(identity): add gt commit wrapper and gt trail command

gt-f6mkz: Agent git identity
- Add `gt commit` wrapper that sets git author from agent identity
- Identity mapping: gastown/crew/jack → gastown.crew.jack@gastown.local
- Add `agent_email_domain` to TownSettings (default: gastown.local)
- Add `gt config agent-email-domain` command to manage domain

gt-j1m5v: gt trail command
- Add `gt trail` with aliases `gt recent` and `gt recap`
- Subcommands: commits, beads, hooks
- Flags: --since, --limit, --json, --all
- Filter commits by agent email domain

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

internal/cmd/commit.go

@@ -0,0 +1,118 @@
+package cmd
+
+import (
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/spf13/cobra"
+	"github.com/steveyegge/gastown/internal/config"
+	"github.com/steveyegge/gastown/internal/workspace"
+)
+
+// DefaultAgentEmailDomain is the default domain for agent git emails.
+const DefaultAgentEmailDomain = "gastown.local"
+
+var commitCmd = &cobra.Command{
+	Use:   "commit [flags] [-- git-commit-args...]",
+	Short: "Git commit with automatic agent identity",
+	Long: `Git commit wrapper that automatically sets git author identity for agents.
+
+When run by an agent (GT_ROLE set), this command:
+1. Detects the agent identity from environment variables
+2. Converts it to a git-friendly name and email
+3. Runs 'git commit' with the correct identity
+
+The email domain is configurable in town settings (agent_email_domain).
+Default: gastown.local
+
+Examples:
+  gt commit -m "Fix bug"              # Commit as current agent
+  gt commit -am "Quick fix"           # Stage all and commit
+  gt commit -- --amend                # Amend last commit
+
+Identity mapping:
+  Agent: gastown/crew/jack  →  Name: gastown/crew/jack
+                                Email: gastown.crew.jack@gastown.local
+
+When run without GT_ROLE (human), passes through to git commit with no changes.`,
+	RunE:               runCommit,
+	DisableFlagParsing: true, // We'll parse flags ourselves to pass them to git
+}
+
+func init() {
+	commitCmd.GroupID = GroupWork
+	rootCmd.AddCommand(commitCmd)
+}
+
+func runCommit(cmd *cobra.Command, args []string) error {
+	// Detect agent identity
+	identity := detectSender()
+
+	// If overseer (human), just pass through to git commit
+	if identity == "overseer" {
+		return runGitCommit(args, "", "")
+	}
+
+	// Load agent email domain from town settings
+	domain := DefaultAgentEmailDomain
+	townRoot, err := workspace.FindFromCwd()
+	if err == nil && townRoot != "" {
+		settings, err := config.LoadOrCreateTownSettings(config.TownSettingsPath(townRoot))
+		if err == nil && settings.AgentEmailDomain != "" {
+			domain = settings.AgentEmailDomain
+		}
+	}
+
+	// Convert identity to git-friendly email
+	// "gastown/crew/jack" → "gastown.crew.jack@domain"
+	email := identityToEmail(identity, domain)
+
+	// Use identity as the author name (human-readable)
+	name := identity
+
+	return runGitCommit(args, name, email)
+}
+
+// identityToEmail converts a Gas Town identity to a git email address.
+// "gastown/crew/jack" → "gastown.crew.jack@domain"
+// "mayor/" → "mayor@domain"
+func identityToEmail(identity, domain string) string {
+	// Remove trailing slash if present
+	identity = strings.TrimSuffix(identity, "/")
+
+	// Replace slashes with dots for email local part
+	localPart := strings.ReplaceAll(identity, "/", ".")
+
+	return localPart + "@" + domain
+}
+
+// runGitCommit executes git commit with optional identity override.
+// If name and email are empty, runs git commit with no overrides.
+// Preserves git's exit code for proper wrapper behavior.
+func runGitCommit(args []string, name, email string) error {
+	var gitArgs []string
+
+	// If we have an identity, prepend -c flags
+	if name != "" && email != "" {
+		gitArgs = append(gitArgs, "-c", "user.name="+name)
+		gitArgs = append(gitArgs, "-c", "user.email="+email)
+	}
+
+	gitArgs = append(gitArgs, "commit")
+	gitArgs = append(gitArgs, args...)
+
+	gitCmd := exec.Command("git", gitArgs...)
+	gitCmd.Stdin = os.Stdin
+	gitCmd.Stdout = os.Stdout
+	gitCmd.Stderr = os.Stderr
+
+	if err := gitCmd.Run(); err != nil {
+		// Preserve git's exit code for proper wrapper behavior
+		if exitErr, ok := err.(*exec.ExitError); ok {
+			os.Exit(exitErr.ExitCode())
+		}
+		return err
+	}
+	return nil
+}