Hardening follow-ups (1.4.1)

CHANGELOG.md

@@ -7,6 +7,27 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.4.1] - 2026-10-16
+
+Hardening-only patch. No new features or dependency changes.
+
+### Security
+
+- **Strict CSP on bridge HTML.** Dashboard shell responses send `Content-Security-Policy` with
+  `script-src 'self'` and `style-src 'self' 'unsafe-inline'` so inline styles from JS/SVG still work.
+- **Electron navigation lockdown.** `setWindowOpenHandler` denies popups; `will-navigate` allows only
+  the app’s loopback bridge URL.
+- **Port 3847 identity.** `/api/status` exposes `bridgeId`; Electron verifies it before loading when
+  reusing an existing listener, and the bridge refuses foreign `ok` responses without the id.
+- **Atomic event-log replace.** Prune and clear write a temp file in the log directory and rename over
+  the JSONL instead of truncating in place.
+- **Status class escaping.** `formatStatusHtml` escapes wrapper class names via `SafeHtml`.
+
+### Changed
+
+- **CSV TOTAL label.** The TOTAL row notes that explorer and researcher lines are excluded because their
+  tokens are already counted in Haiku (numbers unchanged).
+
 ## [1.4.0] - 2026-10-16
 
 Correctness pass on the Live path. The bridge was reading a transcript shape Cursor does not
@@ -262,7 +283,8 @@ audio fix; see Fixed.
 
 - Token and session cost figures are illustrative estimates, not official Cursor billing.
 
-[Unreleased]: https://github.com/thymeed/agent-workshop/compare/v1.4.0...HEAD
+[Unreleased]: https://github.com/thymeed/agent-workshop/compare/v1.4.1...HEAD
+[1.4.1]: https://github.com/thymeed/agent-workshop/compare/v1.4.0...v1.4.1
 [1.4.0]: https://github.com/thymeed/agent-workshop/compare/v1.3.1...v1.4.0
 [1.3.1]: https://github.com/thymeed/agent-workshop/compare/v1.3.0...v1.3.1
 [1.3.0]: https://github.com/thymeed/agent-workshop/compare/v1.2.0...v1.3.0

README.md

@@ -2,7 +2,7 @@
 
 [![CI](https://github.com/thymeed/agent-workshop/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/thymeed/agent-workshop/actions/workflows/ci.yml)
 [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](LICENSE)
-[![Version](https://img.shields.io/badge/version-1.4.0-informational)](CHANGELOG.md)
+[![Version](https://img.shields.io/badge/version-1.4.1-informational)](CHANGELOG.md)
 
 Desktop dashboard that shows how a Cursor Agents session routes work across Opus (parent), Fable (advisor), Worker (Sonnet), and Explorer / Researcher (Haiku).
 

dashboard/bill-math.js

@@ -143,7 +143,7 @@
     });
     lines.push(
       [
-        "TOTAL",
+        "TOTAL (excl. explorer/researcher; in Haiku)",
         summary.totals.inputTokens,
         summary.totals.outputTokens,
         summary.totals.estimatedCostUsd

dashboard/cards.js

@@ -305,7 +305,7 @@
     }
     var plain = prettyStatusText(inner.replace(/<[^>]+>/g, " "));
     var safe = escapeHtmlText(plain);
-    if (cls) return '<span class="' + cls + '">' + safe + "</span>";
+    if (cls) return '<span class="' + escapeHtmlText(cls) + '">' + safe + "</span>";
     return safe;
   }
 

electron/main.js

@@ -6,9 +6,12 @@
  */
 "use strict";
 
-const { app, BrowserWindow, Notification } = require("electron");
+const http = require("http");
+const { app, BrowserWindow, Notification, dialog } = require("electron");
 const path = require("path");
-const { startBridge, stopBridge } = require(path.join(__dirname, "..", "live-bridge.js"));
+const { startBridge, stopBridge, BRIDGE_ID } = require(
+  path.join(__dirname, "..", "live-bridge.js")
+);
 
 const PORT = Number(process.env.CURSOR_BRIDGE_PORT || 3847);
 const WINDOW_TITLE = "Cursor Agents · Model Routing";
@@ -50,6 +53,51 @@ function showAgentAlert(alert) {
   }
 }
 
+function isAllowedNavigationUrl(urlString, port) {
+  try {
+    const u = new URL(urlString);
+    if (u.protocol !== "http:") return false;
+    const host = u.hostname.replace(/^\[|\]$/g, "");
+    if (host !== "127.0.0.1" && host !== "localhost" && host !== "::1") return false;
+    const urlPort = u.port || "80";
+    return urlPort === String(port);
+  } catch (_e) {
+    return false;
+  }
+}
+
+function probeBridgeIdentity(port) {
+  return new Promise((resolve) => {
+    const req = http.get(
+      {
+        host: "127.0.0.1",
+        port,
+        path: "/api/status",
+        timeout: 2000
+      },
+      (res) => {
+        let body = "";
+        res.on("data", (c) => {
+          body += c;
+        });
+        res.on("end", () => {
+          try {
+            const j = JSON.parse(body);
+            resolve(j && j.ok === true && j.bridgeId === BRIDGE_ID ? j : null);
+          } catch (_e) {
+            resolve(null);
+          }
+        });
+      }
+    );
+    req.on("timeout", () => {
+      req.destroy();
+      resolve(null);
+    });
+    req.on("error", () => resolve(null));
+  });
+}
+
 async function bootBridge() {
   // Start the bridge in-process: quiet, no console chatter, no spawned cmd/node.
   const result = await startBridge({
@@ -64,6 +112,18 @@ async function bootBridge() {
 
 async function createWindow() {
   const bridge = await bootBridge();
+  const identity = await probeBridgeIdentity(bridge.port);
+  if (!identity) {
+    dialog.showErrorBox(
+      WINDOW_TITLE,
+      `Could not verify the model-routing bridge on port ${bridge.port}. ` +
+        "Another app may be using that port, or the bridge failed to start. " +
+        "Close other listeners on this port and restart the app."
+    );
+    await shutdown();
+    app.quit();
+    return;
+  }
 
   mainWindow = new BrowserWindow({
     width: 1180,
@@ -82,6 +142,14 @@ async function createWindow() {
   });
 
   mainWindow.setMenuBarVisibility(false);
+
+  mainWindow.webContents.setWindowOpenHandler(() => ({ action: "deny" }));
+  mainWindow.webContents.on("will-navigate", (event, url) => {
+    if (!isAllowedNavigationUrl(url, bridge.port)) {
+      event.preventDefault();
+    }
+  });
+
   mainWindow.on("page-title-updated", (e) => {
     e.preventDefault();
     mainWindow.setTitle(WINDOW_TITLE);

lib/bridge-http.js

@@ -7,6 +7,18 @@ const path = require("path");
 const DASHBOARD = path.join(__dirname, "..", "model-routing-dashboard.html");
 const STATIC_ROOT = path.join(__dirname, "..", "dashboard");
 
+/** Tight CSP for the dashboard shell (external scripts; inline styles from JS/SVG). */
+const DASHBOARD_CSP =
+  "default-src 'self'; " +
+  "script-src 'self'; " +
+  "style-src 'self' 'unsafe-inline'; " +
+  "connect-src 'self'; " +
+  "img-src 'self' data:; " +
+  "font-src 'self'; " +
+  "object-src 'none'; " +
+  "base-uri 'self'; " +
+  "frame-ancestors 'none'";
+
 const MIME = {
   ".html": "text/html; charset=utf-8",
   ".css": "text/css; charset=utf-8",
@@ -140,7 +152,8 @@ function serveDashboard(res) {
     }
     res.writeHead(200, {
       "Content-Type": "text/html; charset=utf-8",
-      "Cache-Control": "no-store"
+      "Cache-Control": "no-store",
+      "Content-Security-Policy": DASHBOARD_CSP
     });
     res.end(data);
   });
@@ -198,6 +211,7 @@ function serveStatic(urlPath, res) {
 module.exports = {
   DASHBOARD,
   STATIC_ROOT,
+  DASHBOARD_CSP,
   MIME,
   sendJson,
   readRequestBody,

lib/event-log.js

@@ -204,20 +204,43 @@ function secureLogFile(filePath) {
   }
 }
 
+function replaceLogFile(filePath, data) {
+  ensureParentDir(filePath);
+  const dir = path.dirname(filePath);
+  const tmpPath = path.join(
+    dir,
+    "." + path.basename(filePath) + "." + process.pid + "." + Date.now() + ".tmp"
+  );
+  try {
+    if (usePosixLogPermissions()) {
+      fs.writeFileSync(tmpPath, data, { encoding: "utf8", mode: LOG_FILE_MODE });
+    } else {
+      fs.writeFileSync(tmpPath, data, "utf8");
+    }
+    fs.renameSync(tmpPath, filePath);
+    secureLogFile(filePath);
+  } catch (e) {
+    try {
+      if (fs.existsSync(tmpPath)) fs.unlinkSync(tmpPath);
+    } catch (_unlink) {
+      /* ignore */
+    }
+    throw e;
+  }
+}
+
 function writeLogBytes(filePath, data, append) {
   ensureParentDir(filePath);
-  if (usePosixLogPermissions()) {
-    if (append) {
+  if (append) {
+    if (usePosixLogPermissions()) {
       fs.appendFileSync(filePath, data, { encoding: "utf8", mode: LOG_FILE_MODE });
+      secureLogFile(filePath);
     } else {
-      fs.writeFileSync(filePath, data, { encoding: "utf8", mode: LOG_FILE_MODE });
+      fs.appendFileSync(filePath, data, "utf8");
     }
-    secureLogFile(filePath);
-  } else if (append) {
-    fs.appendFileSync(filePath, data, "utf8");
-  } else {
-    fs.writeFileSync(filePath, data, "utf8");
+    return;
   }
+  replaceLogFile(filePath, data);
 }
 
 /**

live-bridge.js

@@ -132,6 +132,8 @@ let currentIngestFile = "";
 let currentIngestLine = 0;
 
 let PORT = 3847;
+/** Identity token for /api/status; Electron refuses foreign listeners on the bridge port. */
+const BRIDGE_ID = "cursor-agents-model-routing-v1";
 /** @type {string} */
 let TRANSCRIPTS = emptyTranscripts();
 /** @type {string|null} */
@@ -597,6 +599,7 @@ function selectProject(id) {
 function statusPayload() {
   return {
     ok: true,
+    bridgeId: BRIDGE_ID,
     port: PORT,
     transcripts: TRANSCRIPTS,
     projectId: currentProjectId,
@@ -1554,7 +1557,7 @@ function probeExistingBridge(port) {
         res.on("end", () => {
           try {
             const j = JSON.parse(body);
-            resolve(j && j.ok === true ? j : null);
+            resolve(j && j.ok === true && j.bridgeId === BRIDGE_ID ? j : null);
           } catch (_) {
             resolve(null);
           }
@@ -1781,6 +1784,7 @@ function clearHistory() {
 }
 
 module.exports = {
+  BRIDGE_ID,
   startBridge,
   stopBridge,
   discoverProjects,

package.json

@@ -1,6 +1,6 @@
 {
   "name": "agent-workshop",
-  "version": "1.4.0",
+  "version": "1.4.1",
   "description": "Cursor Agents · Model Routing. Electron desktop dashboard with in-process live bridge",
   "main": "electron/main.js",
   "author": {

test/bridge-guards.test.js

@@ -156,6 +156,19 @@ async function testStaticAndCors(port) {
   const home = await request(port, { path: "/" });
   assert.strictEqual(home.status, 200, `GET /: expected 200, got ${home.status}`);
   assert.ok(/text\/html/.test(home.headers["content-type"]), "GET / must be text/html");
+  const csp = home.headers["content-security-policy"] || "";
+  assert.ok(
+    csp.includes("script-src 'self'"),
+    "GET / must send a strict CSP with script-src 'self'"
+  );
+  assert.ok(
+    csp.includes("style-src 'self' 'unsafe-inline'"),
+    "GET / CSP must allow inline styles for the dashboard"
+  );
+
+  const status = await request(port, { path: "/api/status" });
+  const statusJson = JSON.parse(status.body);
+  assert.ok(statusJson.bridgeId, "status must include bridgeId for port identity checks");
 
   const css = await request(port, { path: "/dashboard/styles.css" });
   assert.strictEqual(css.status, 200, `GET stylesheet: expected 200, got ${css.status}`);

test/dashboard-units.test.js

@@ -258,7 +258,7 @@ async function main() {
       "CSV header must be stable"
     );
     assert.ok(
-      csvLines.some((l) => l.startsWith("TOTAL,")),
+      csvLines.some((l) => l.startsWith("TOTAL (excl. explorer/researcher; in Haiku),")),
       "CSV must carry a TOTAL row"
     );
     assert.strictEqual(csvLines[1].split(",").length, 4, "CSV data rows keep four columns");

test/event-log.test.js

@@ -293,6 +293,35 @@ function testContractShape() {
   if (errors.length) throw new Error("contract failed:\n- " + errors.join("\n- "));
 }
 
+function testReplacePreservesLogOnWriteFailure() {
+  const dir = tmpDir("atomic-fail");
+  const log = createEventLog({ logDir: dir });
+  log.append(sampleEvent({ agentId: "keep-me" }));
+  const p = log.getLogPath();
+  const before = fs.readFileSync(p, "utf8");
+  assert(before.includes("keep-me"), "seed event present");
+
+  const origWrite = fs.writeFileSync;
+  fs.writeFileSync = function (file, ...args) {
+    if (String(file).includes(".tmp")) {
+      throw new Error("simulated atomic write failure");
+    }
+    return origWrite.call(fs, file, ...args);
+  };
+  try {
+    let threw = false;
+    try {
+      log.clear();
+    } catch (_e) {
+      threw = true;
+    }
+    assert(threw, "clear must fail when the temp write fails");
+    assert(fs.readFileSync(p, "utf8") === before, "original log must survive a failed replace");
+  } finally {
+    fs.writeFileSync = origWrite;
+  }
+}
+
 function testRetentionAndClear() {
   const dir = tmpDir("retain");
   const log = createEventLog({ logDir: dir, retentionMs: 1000 });
@@ -474,6 +503,7 @@ async function main() {
   testRedactionSignedUrls();
   testPemFullBlockRedaction();
   testContractShape();
+  testReplacePreservesLogOnWriteFailure();
   testRetentionAndClear();
   testExistingLogDirChmodOnStart();
   testFilePermissions();