diff --git a/packages/web/src/components/DirectTerminal.tsx b/packages/web/src/components/DirectTerminal.tsx
index e5e8c11b1..ab32dc4ee 100644
--- a/packages/web/src/components/DirectTerminal.tsx
+++ b/packages/web/src/components/DirectTerminal.tsx
@@ -21,6 +21,40 @@ interface DirectTerminalProps {
   height?: string;
 }
 
+interface DirectTerminalLocation {
+  protocol: string;
+  hostname: string;
+  host: string;
+  port: string;
+}
+
+interface DirectTerminalWsUrlOptions {
+  location: DirectTerminalLocation;
+  sessionId: string;
+  proxyWsPath?: string;
+  directTerminalPort?: string;
+}
+
+export function buildDirectTerminalWsUrl({
+  location,
+  sessionId,
+  proxyWsPath,
+  directTerminalPort,
+}: DirectTerminalWsUrlOptions): string {
+  const protocol = location.protocol === "https:" ? "wss:" : "ws:";
+  if (proxyWsPath) {
+    // Path-based proxy uses host so non-standard ports are preserved.
+    return `${protocol}//${location.host}${proxyWsPath}?session=${encodeURIComponent(sessionId)}`;
+  }
+
+  if (location.port === "" || location.port === "443" || location.port === "80") {
+    return `${protocol}//${location.hostname}/ao-terminal-ws?session=${encodeURIComponent(sessionId)}`;
+  }
+
+  const port = directTerminalPort ?? "14801";
+  return `${protocol}//${location.hostname}:${port}/ws?session=${encodeURIComponent(sessionId)}`;
+}
+
 /**
  * Direct xterm.js terminal with native WebSocket connection.
  * Implements Extended Device Attributes (XDA) handler to enable
@@ -186,22 +220,12 @@ export function DirectTerminal({
         // WebSocket URL (stable across reconnects)
         // When accessed via reverse proxy (HTTPS on standard port), use path-based
         // WebSocket endpoint instead of direct port access.
-        const protocol = window.location.protocol === "https:" ? "wss:" : "ws:";
-        const hostname = window.location.hostname;
-        const host = window.location.host;
-        const proxyWsPath = process.env.NEXT_PUBLIC_TERMINAL_WS_PATH;
-        let wsUrl: string;
-        if (proxyWsPath) {
-          // Path-based proxy (e.g. /ao-terminal-ws)
-          wsUrl = `${protocol}//${host}${proxyWsPath}?session=${encodeURIComponent(sessionId)}`;
-        } else if (window.location.port === "" || window.location.port === "443" || window.location.port === "80") {
-          // Behind reverse proxy on standard port — use path-based endpoint
-          wsUrl = `${protocol}//${hostname}/ao-terminal-ws?session=${encodeURIComponent(sessionId)}`;
-        } else {
-          // Direct access (dev mode) — use direct port
-          const port = process.env.NEXT_PUBLIC_DIRECT_TERMINAL_PORT ?? "14801";
-          wsUrl = `${protocol}//${hostname}:${port}/ws?session=${encodeURIComponent(sessionId)}`;
-        }
+        const wsUrl = buildDirectTerminalWsUrl({
+          location: window.location,
+          sessionId,
+          proxyWsPath: process.env.NEXT_PUBLIC_TERMINAL_WS_PATH,
+          directTerminalPort: process.env.NEXT_PUBLIC_DIRECT_TERMINAL_PORT,
+        });
 
         // ── Preserve selection while terminal receives output ────────
         // xterm.js clears the selection on every terminal.write(). We
diff --git a/packages/web/src/components/__tests__/DirectTerminal.test.ts b/packages/web/src/components/__tests__/DirectTerminal.test.ts
new file mode 100644
index 000000000..20ff16756
--- /dev/null
+++ b/packages/web/src/components/__tests__/DirectTerminal.test.ts
@@ -0,0 +1,63 @@
+import { describe, it, expect } from "vitest";
+import { buildDirectTerminalWsUrl } from "@/components/DirectTerminal";
+
+describe("buildDirectTerminalWsUrl", () => {
+  it("keeps non-standard port when proxy path override is set", () => {
+    const wsUrl = buildDirectTerminalWsUrl({
+      location: {
+        protocol: "https:",
+        hostname: "example.com",
+        host: "example.com:8443",
+        port: "8443",
+      },
+      sessionId: "session-1",
+      proxyWsPath: "/ao-terminal-ws",
+    });
+
+    expect(wsUrl).toBe("wss://example.com:8443/ao-terminal-ws?session=session-1");
+  });
+
+  it("uses proxy path without port when default port is used", () => {
+    const wsUrl = buildDirectTerminalWsUrl({
+      location: {
+        protocol: "https:",
+        hostname: "example.com",
+        host: "example.com",
+        port: "",
+      },
+      sessionId: "session-2",
+      proxyWsPath: "/ao-terminal-ws",
+    });
+
+    expect(wsUrl).toBe("wss://example.com/ao-terminal-ws?session=session-2");
+  });
+
+  it("uses default path-based endpoint on standard ports when no proxy override is set", () => {
+    const wsUrl = buildDirectTerminalWsUrl({
+      location: {
+        protocol: "https:",
+        hostname: "example.com",
+        host: "example.com",
+        port: "443",
+      },
+      sessionId: "session-3",
+    });
+
+    expect(wsUrl).toBe("wss://example.com/ao-terminal-ws?session=session-3");
+  });
+
+  it("uses direct terminal port on non-standard ports when no proxy override is set", () => {
+    const wsUrl = buildDirectTerminalWsUrl({
+      location: {
+        protocol: "http:",
+        hostname: "localhost",
+        host: "localhost:3000",
+        port: "3000",
+      },
+      sessionId: "session-4",
+      directTerminalPort: "14888",
+    });
+
+    expect(wsUrl).toBe("ws://localhost:14888/ws?session=session-4");
+  });
+});