feat(update): add source-based update flow from local git checkout

Makefile

@@ -3,7 +3,8 @@
 BINARY_NAME=agent-deck
 BUILD_DIR=./build
 VERSION=$(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
-LDFLAGS=-ldflags "-X main.Version=$(VERSION)"
+COMMIT=$(shell git rev-parse --short HEAD 2>/dev/null)
+LDFLAGS=-ldflags "-X main.Version=$(VERSION) -X main.Commit=$(COMMIT)"
 
 # Build the binary
 build:

cmd/agent-deck/main.go

@@ -33,6 +33,17 @@ import (
 
 const Version = "0.27.5"
 
+// Commit is the git commit hash, injected at build time via ldflags.
+var Commit string
+
+// VersionString returns the version with commit hash if available.
+func VersionString() string {
+	if Commit != "" {
+		return Version + " (" + Commit + ")"
+	}
+	return Version
+}
+
 // Table column widths for list command output
 const (
 	tableColTitle     = 20
@@ -79,19 +90,32 @@ func promptForUpdate() bool {
 	}
 
 	info, err := update.CheckForUpdate(Version, false)
-	if err != nil || info == nil || !info.Available {
+	if err != nil || info == nil {
+		return false
+	}
+
+	sourceRebuild, sourceHead := sourceRebuildNeeded()
+	if !info.Available && !sourceRebuild {
 		return false
 	}
 
 	// If auto_update is disabled, just show notification (don't prompt)
 	if !settings.AutoUpdate {
-		fmt.Fprintf(os.Stderr, "\n💡 Update available: v%s → v%s (run: agent-deck update)\n",
-			info.CurrentVersion, info.LatestVersion)
+		if sourceRebuild {
+			fmt.Fprintf(os.Stderr, "\n💡 Rebuild available: binary %s vs source %s (run: agent-deck update)\n", Commit, sourceHead)
+		} else {
+			fmt.Fprintf(os.Stderr, "\n💡 Update available: v%s → v%s (run: agent-deck update)\n",
+				info.CurrentVersion, info.LatestVersion)
+		}
 		return false
 	}
 
 	// auto_update is enabled - prompt user
-	fmt.Printf("\n⬆ Update available: v%s → v%s\n", info.CurrentVersion, info.LatestVersion)
+	if sourceRebuild {
+		fmt.Printf("\n⬆ Rebuild available: binary %s vs source %s\n", Commit, sourceHead)
+	} else {
+		fmt.Printf("\n⬆ Update available: v%s → v%s\n", info.CurrentVersion, info.LatestVersion)
+	}
 	fmt.Print("Update now? [Y/n]: ")
 
 	var response string
@@ -198,7 +222,7 @@ func main() {
 	if len(args) > 0 {
 		switch args[0] {
 		case "version", "--version", "-v":
-			fmt.Printf("Agent Deck v%s\n", Version)
+			fmt.Printf("Agent Deck v%s\n", VersionString())
 			return
 		case "help", "--help", "-h":
 			printHelp()
@@ -313,6 +337,7 @@ func main() {
 
 	// Set version for UI update checking
 	ui.SetVersion(Version)
+	ui.SetCommit(Commit)
 
 	// Initialize theme from config (resolves "system" to actual dark/light)
 	theme := session.ResolveTheme()
@@ -2101,7 +2126,7 @@ func handleUpdate(args []string) {
 		os.Exit(1)
 	}
 
-	fmt.Printf("Agent Deck v%s\n", Version)
+	fmt.Printf("Agent Deck v%s\n", VersionString())
 	fmt.Println("Checking for updates...")
 
 	// Always force check when user explicitly runs 'update' command
@@ -2111,14 +2136,21 @@ func handleUpdate(args []string) {
 		fmt.Printf("Error checking for updates: %v\n", err)
 		os.Exit(1)
 	}
+	sourceRebuild, sourceHead := sourceRebuildNeeded()
 
-	if !info.Available {
+	if !info.Available && !sourceRebuild {
 		fmt.Println("✓ You're running the latest version!")
 		return
 	}
 
-	fmt.Printf("\n⬆ Update available: v%s → v%s\n", info.CurrentVersion, info.LatestVersion)
-	fmt.Printf("  Release: %s\n", info.ReleaseURL)
+	if sourceRebuild && !info.Available {
+		fmt.Printf("\n⬆ Rebuild available: binary %s vs source %s\n", Commit, sourceHead)
+	} else {
+		fmt.Printf("\n⬆ Update available: v%s → v%s\n", info.CurrentVersion, info.LatestVersion)
+		if info.ReleaseURL != "" {
+			fmt.Printf("  %s\n", info.ReleaseURL)
+		}
+	}
 
 	// Fetch and display changelog
 	displayChangelog(info.CurrentVersion, info.LatestVersion)
@@ -2190,6 +2222,29 @@ func handleUpdate(args []string) {
 	updateRemotesAfterLocalUpdate(info.LatestVersion)
 }
 
+// sourceRebuildNeeded reports whether source-mode should rebuild the binary even
+// when the source checkout is not behind source_ref (e.g. binary commit differs).
+func sourceRebuildNeeded() (bool, string) {
+	settings := session.GetUpdateSettings()
+	if settings.SourceDir == "" || Commit == "" {
+		return false, ""
+	}
+
+	cmd := exec.Command("git", "rev-parse", "--short", "HEAD")
+	cmd.Dir = settings.SourceDir
+	out, err := cmd.Output()
+	if err != nil {
+		return false, ""
+	}
+
+	head := strings.TrimSpace(string(out))
+	if head == "" || head == Commit {
+		return false, head
+	}
+
+	return true, head
+}
+
 func runHomebrewUpgradeWithRefresh(homebrewUpgradeCmd string) error {
 	cmdParts := strings.Fields(homebrewUpgradeCmd)
 	if len(cmdParts) == 0 {
@@ -2261,7 +2316,7 @@ func drainStdin() {
 }
 
 func printHelp() {
-	fmt.Printf("Agent Deck v%s\n", Version)
+	fmt.Printf("Agent Deck v%s\n", VersionString())
 	fmt.Println("Terminal session manager for AI coding agents")
 	fmt.Println()
 	fmt.Println("Usage: agent-deck [-p profile] [command]")

internal/session/userconfig.go

@@ -293,6 +293,15 @@ type UpdateSettings struct {
 	// NotifyInCLI shows update notification in CLI commands (not just TUI)
 	// Default: true
 	NotifyInCLI bool `toml:"notify_in_cli"`
+
+	// SourceDir is the absolute path to a local git checkout. When set,
+	// updates pull and build from source instead of downloading release
+	// binaries. Leave empty to use the default release-based updates.
+	SourceDir string `toml:"source_dir"`
+
+	// SourceRef is the remote tracking ref to follow (e.g. "origin/main").
+	// Default: "origin/main"
+	SourceRef string `toml:"source_ref"`
 }
 
 // PreviewSettings defines preview pane configuration
@@ -1423,6 +1432,9 @@ func GetUpdateSettings() UpdateSettings {
 	if settings.CheckIntervalHours <= 0 {
 		settings.CheckIntervalHours = 24
 	}
+	if settings.SourceRef == "" {
+		settings.SourceRef = "origin/main"
+	}
 
 	return settings
 }

internal/ui/help.go

@@ -308,7 +308,7 @@ func (h *HelpOverlay) View() string {
 	}
 	lines = append(lines, "")
 	lines = append(lines, separatorStyle.Render(strings.Repeat("─", separatorWidth)))
-	lines = append(lines, versionStyle.Render("Agent Deck v"+Version))
+	lines = append(lines, versionStyle.Render("Agent Deck v"+DisplayVersion()))
 
 	totalLines := len(lines)
 

internal/ui/home.go

@@ -39,11 +39,27 @@ import (
 // Version is set by main.go for update checking
 var Version = "0.0.0"
 
+// Commit is the git commit hash, set by main.go at startup.
+var Commit string
+
 // SetVersion sets the current version for update checking
 func SetVersion(v string) {
 	Version = v
 }
 
+// SetCommit sets the git commit hash for display in the UI.
+func SetCommit(c string) {
+	Commit = c
+}
+
+// DisplayVersion returns the version string with commit hash if available.
+func DisplayVersion() string {
+	if Commit != "" {
+		return Version + " (" + Commit + ")"
+	}
+	return Version
+}
+
 // Structured loggers for UI components
 var (
 	uiLog     = logging.ForComponent(logging.CompUI)
@@ -7540,7 +7556,7 @@ func (h *Home) View() string {
 	versionStyle := lipgloss.NewStyle().
 		Foreground(ColorComment).
 		Faint(true)
-	versionBadge := versionStyle.Render("v" + Version)
+	versionBadge := versionStyle.Render("v" + DisplayVersion())
 
 	// Fill remaining header space
 	headerLeft := lipgloss.JoinHorizontal(lipgloss.Left, logo, "  ", title, "  ", stats)