diff --git a/tests/js/browser-globals.test.js b/tests/js/browser-globals.test.js
new file mode 100644
index 0000000..135cde6
--- /dev/null
+++ b/tests/js/browser-globals.test.js
@@ -0,0 +1,74 @@
+// Run with: node --test tests/js/
+// Each page module is a UMD-style IIFE: CommonJS export under Node, a window
+// global in the browser. This loads every module the way a browser would and
+// checks the global name the pages rely on.
+const test = require("node:test");
+const assert = require("node:assert/strict");
+const fs = require("node:fs");
+const path = require("node:path");
+const vm = require("node:vm");
+
+const MODULES = {
+    "html-escape.js": ["HtmlEscape", "escapeHtml", "escapeAttr"],
+    "data-actions.js": ["DataActions"],
+    "api-client.js": ["ApiClient"],
+    "list-state.js": ["ListState"],
+    "sse-stream.js": ["SseStream"],
+    "png-metadata.js": ["PngMetadata"],
+    "view-router.js": ["ViewRouter"],
+    "prompt-list-sort.js": ["PromptListSort"],
+    "comfy-metadata.js": ["ComfyMetadata"],
+};
+
+function loadInFakeBrowser(file) {
+    const source = fs.readFileSync(path.join(__dirname, "../../web/js", file), "utf8");
+    const window = {};
+    window.window = window;
+    const context = vm.createContext({
+        window,
+        globalThis: window,
+        console,
+        TextDecoder,
+        TextEncoder,
+        AbortController,
+        URLSearchParams,
+        Symbol,
+        Object,
+        Array,
+        Number,
+        String,
+        Math,
+        Set,
+        Map,
+        JSON,
+        Error,
+        Promise,
+        DataView,
+        Uint8Array,
+        ArrayBuffer,
+    });
+    vm.runInContext(source, context, { filename: file });
+    return window;
+}
+
+for (const [file, globals] of Object.entries(MODULES)) {
+    test(`${file} exposes ${globals.join(", ")} on window when module is undefined`, () => {
+        const window = loadInFakeBrowser(file);
+        for (const name of globals) {
+            assert.ok(window[name], `${name} missing`);
+            assert.ok(["object", "function"].includes(typeof window[name]), `${name} is a ${typeof window[name]}`);
+        }
+    });
+}
+
+test("the browser escapeHtml global is the same function as HtmlEscape.escapeHtml", () => {
+    const window = loadInFakeBrowser("html-escape.js");
+    assert.equal(window.escapeHtml, window.HtmlEscape.escapeHtml);
+    assert.equal(window.escapeAttr, window.escapeHtml);
+    assert.equal(window.escapeHtml(`<a href="x">`), "&lt;a href=&quot;x&quot;&gt;");
+});
+
+test("the browser ViewRouter global resolves the tags deep link", () => {
+    const window = loadInFakeBrowser("view-router.js");
+    assert.equal(window.ViewRouter.resolveView("#/tags/a"), "tags");
+});
diff --git a/tests/js/sse-stream.test.js b/tests/js/sse-stream.test.js
index 038c4f4..2c5465f 100644
--- a/tests/js/sse-stream.test.js
+++ b/tests/js/sse-stream.test.js
@@ -104,6 +104,50 @@ test("close() aborts the request and suppresses later callbacks", async () => {
     assert.equal(errors, 0);
 });
 
+test("connect forwards a request body and an Accept header", async () => {
+    let init = null;
+    const fetchImpl = async (_url, i) => { init = i; return new Response(streamOf([]), { status: 200 }); };
+    const source = connect("/x", { method: "POST", body: '{"a":1}', fetchImpl });
+    await until(() => source.readyState === source.CLOSED);
+    assert.equal(init.body, '{"a":1}');
+    assert.equal(init.headers.Accept, "text/event-stream");
+});
+
+test("events arriving with no onmessage handler are dropped without error", async () => {
+    const fetchImpl = async () => new Response(streamOf(["data: 1\n\n", "data: 2\n\n"]), { status: 200 });
+    const source = connect("/x", { fetchImpl });
+    let errors = 0;
+    source.onerror = () => errors++;
+    await until(() => source.readyState === source.CLOSED);
+    assert.equal(errors, 0);
+});
+
+test("close() during delivery stops further messages and skips onclose", async () => {
+    const seen = [];
+    let closed = false;
+    const fetchImpl = async () => new Response(streamOf(["data: 1\n\ndata: 2\n\ndata: 3\n\n"]), { status: 200 });
+    const source = connect("/x", { fetchImpl });
+    source.onmessage = (e) => { seen.push(e.data); if (e.data === "1") source.close(); };
+    source.onclose = () => { closed = true; };
+    await until(() => source.readyState === source.CLOSED);
+    await new Promise((r) => setTimeout(r, 10));
+    assert.deepEqual(seen, ["1"]);
+    assert.equal(closed, false);
+});
+
+test("close() before the response arrives discards it silently", async () => {
+    let resolveFetch;
+    let errors = 0;
+    const fetchImpl = () => new Promise((resolve) => { resolveFetch = resolve; });
+    const source = connect("/x", { fetchImpl });
+    source.onerror = () => errors++;
+    source.close();
+    resolveFetch(new Response(streamOf(["data: late\n\n"]), { status: 200 }));
+    await new Promise((r) => setTimeout(r, 10));
+    assert.equal(errors, 0);
+    assert.equal(source.readyState, source.CLOSED);
+});
+
 test("connect defaults to GET and the global fetch", async () => {
     const original = globalThis.fetch;
     let init = null;