fix(web-probe): stabilize browser transport sampling (#717)

Co-authored-by: Codex <codex@noreply.local>

scripts/src/hwlab-node-web-probe-runner-source.ts

@@ -17,6 +17,7 @@ const runDir = path.resolve(process.env.UNIDESK_WEB_PROBE_RUN_DIR || ".state/web
 const userScript = path.resolve(process.env.UNIDESK_WEB_PROBE_USER_SCRIPT || path.join(runDir, "user-script.mjs"));
 const timeoutMs = positiveInteger(process.env.UNIDESK_WEB_PROBE_TIMEOUT_MS, 30000);
 const viewport = parseViewport(process.env.UNIDESK_WEB_PROBE_VIEWPORT || "1440x900");
+const browserProxyMode = parseBrowserProxyMode(process.env.UNIDESK_WEB_PROBE_BROWSER_PROXY_MODE || "auto");
 const playwrightProxy = proxyConfigFromEnv(baseUrl);
 const chromiumLaunchOptions = chromiumLaunchOptionsForProxy(playwrightProxy);
 const artifactRecords = [];
@@ -370,6 +371,7 @@ function scriptHelpers() {
 }
 
 function proxyConfigFromEnv(targetBaseUrl) {
+  if (browserProxyMode === "direct") return null;
   let target;
   try {
     target = new URL(targetBaseUrl);
@@ -425,6 +427,7 @@ function publicNetwork(proxy) {
     },
     browser: {
       proxyMode: proxy === null ? "direct-no-proxy-server" : "explicit-playwright-proxy",
+      requestedProxyMode: browserProxyMode,
       proxyEnvCleared: true,
       valuesRedacted: true,
     },
@@ -432,6 +435,11 @@ function publicNetwork(proxy) {
   };
 }
 
+function parseBrowserProxyMode(raw) {
+  if (raw === "auto" || raw === "direct") return raw;
+  return "auto";
+}
+
 function publicProxyServer(raw) {
   try {
     const parsed = new URL(String(raw || ""));