add bridge version trace output

internal/acp/runtime_version.go

@@ -9,7 +9,7 @@ type imageVersionInfo struct {
 	Version  string `json:"version,omitempty"`
 }
 
-func parseImageVersionInfo(imageRef string) imageVersionInfo {
+func ParseImageVersionInfo(imageRef string) imageVersionInfo {
 	ref := strings.TrimSpace(imageRef)
 	info := imageVersionInfo{ImageRef: ref}
 	if ref == "" {

internal/acp/server.go

@@ -121,7 +121,7 @@ func (s *Server) Handler() http.Handler {
 			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 			_, _ = w.Write([]byte("xworkmate-bridge is running"))
 		case "/api/ping":
-			info := parseImageVersionInfo(os.Getenv("IMAGE"))
+			info := ParseImageVersionInfo(os.Getenv("IMAGE"))
 			resp := map[string]any{
 				"status":  "ok",
 				"image":   info.ImageRef,

internal/acp/web_contract_test.go

@@ -194,7 +194,7 @@ func TestHTTPHandlerBareAliasPathsServeRPC(t *testing.T) {
 }
 
 func TestParseImageVersionInfoHandlesTaggedImageRef(t *testing.T) {
-	info := parseImageVersionInfo("ghcr.io/x-evor/xworkmate-bridge:main-2026-04-12")
+	info := ParseImageVersionInfo("ghcr.io/x-evor/xworkmate-bridge:main-2026-04-12")
 
 	if info.ImageRef != "ghcr.io/x-evor/xworkmate-bridge:main-2026-04-12" {
 		t.Fatalf("expected full image ref, got %q", info.ImageRef)

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 
@@ -11,6 +12,16 @@ import (
 )
 
 func main() {
+	if len(os.Args) > 1 {
+		switch os.Args[1] {
+		case "-v", "--version":
+			if err := printBridgeVersionInfo(); err != nil {
+				fmt.Fprintf(os.Stderr, "%v\n", err)
+				os.Exit(1)
+			}
+			return
+		}
+	}
 	if len(os.Args) > 1 && os.Args[1] == "serve" {
 		if err := acp.Serve(os.Args[2:]); err != nil {
 			fmt.Fprintf(os.Stderr, "%v\n", err)
@@ -39,3 +50,20 @@ func main() {
 
 	toolbridge.Run(os.Stdin, os.Stdout)
 }
+
+func printBridgeVersionInfo() error {
+	info := acp.ParseImageVersionInfo(os.Getenv("IMAGE"))
+	payload := map[string]any{
+		"status":  "ok",
+		"image":   info.ImageRef,
+		"tag":     info.Tag,
+		"commit":  info.Commit,
+		"version": info.Version,
+	}
+	encoded, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+	_, err = os.Stdout.Write(append(encoded, '\n'))
+	return err
+}

main_test.go

@@ -2,10 +2,12 @@ package main
 
 import (
 	"encoding/json"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 )
@@ -129,3 +131,69 @@ func TestRunClaudeReviewSurfacesNonJSONStdout(t *testing.T) {
 		t.Fatal("expected non-json stdout error")
 	}
 }
+
+func TestPrintBridgeVersionInfoMatchesPingContract(t *testing.T) {
+	t.Setenv("IMAGE", "ghcr.io/x-evor/xworkmate-bridge:0123456789abcdef0123456789abcdef01234567")
+
+	output := captureStdout(t, printBridgeVersionInfo)
+
+	var payload map[string]any
+	if err := json.Unmarshal([]byte(output), &payload); err != nil {
+		t.Fatalf("decode version payload: %v", err)
+	}
+	if payload["status"] != "ok" {
+		t.Fatalf("expected status ok, got %#v", payload["status"])
+	}
+	if payload["image"] != "ghcr.io/x-evor/xworkmate-bridge:0123456789abcdef0123456789abcdef01234567" {
+		t.Fatalf("unexpected image ref: %#v", payload["image"])
+	}
+	if payload["tag"] != "0123456789abcdef0123456789abcdef01234567" {
+		t.Fatalf("unexpected tag: %#v", payload["tag"])
+	}
+	if payload["commit"] != "0123456789abcdef0123456789abcdef01234567" {
+		t.Fatalf("unexpected commit: %#v", payload["commit"])
+	}
+	if payload["version"] != "0123456789abcdef0123456789abcdef01234567" {
+		t.Fatalf("unexpected version: %#v", payload["version"])
+	}
+}
+
+func TestPrintBridgeVersionInfoWithoutImageEnv(t *testing.T) {
+	t.Setenv("IMAGE", "")
+
+	output := captureStdout(t, printBridgeVersionInfo)
+	if !strings.Contains(output, `"status":"ok"`) {
+		t.Fatalf("unexpected output: %q", output)
+	}
+}
+
+func captureStdout(t *testing.T, fn func() error) string {
+	t.Helper()
+
+	old := os.Stdout
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatalf("pipe stdout: %v", err)
+	}
+	os.Stdout = w
+	defer func() {
+		os.Stdout = old
+	}()
+
+	done := make(chan string, 1)
+	go func() {
+		var builder strings.Builder
+		_, _ = io.Copy(&builder, r)
+		done <- builder.String()
+	}()
+
+	callErr := fn()
+	_ = w.Close()
+	out := <-done
+	_ = r.Close()
+
+	if callErr != nil {
+		t.Fatalf("call failed: %v", callErr)
+	}
+	return strings.TrimSpace(out)
+}