diff --git a/docs/subsystems/gateway-routing.md b/docs/subsystems/gateway-routing.md
index 0c203b17..b84be269 100644
--- a/docs/subsystems/gateway-routing.md
+++ b/docs/subsystems/gateway-routing.md
@@ -16,7 +16,7 @@ served by a plugin are in [Provider and plugin ownership](provider-plugins.md).
 | Part | Responsibility | Source |
 | --- | --- | --- |
 | Address and caller | `DefaultAddr`. The local token `magpie` and the per-agent `magpie-<agent>` (`TokenFor`). `agentOf` tells which agent asked, first by token, then by User-Agent. | [`gateway.go`](../../internal/gateway/gateway.go) |
-| HTTP surface | `Handler` routes `/v1/chat/completions`, `/v1/responses`, `/v1/messages` (each also without `/v1`), `/v1/models`, Gemini's `/v1beta/models/…`, the Codex backend path, `/mcp/{name}` and the `/v1/magpie/*` status endpoints. A GET on `/v1/responses` (a client opening Responses over a WebSocket) is answered 426, a plain one 405: Responses is relayed over HTTP only. Every route is wrapped in `counted`, `callerGuard`, `withCaller` and `keyLimited`. | [`gateway.go`](../../internal/gateway/gateway.go) |
+| HTTP surface | `Handler` routes `/v1/chat/completions`, `/v1/responses`, `/v1/messages` (each also without `/v1`), `/v1/models`, Gemini's `/v1beta/models/…`, the Codex backend path, `/mcp/{name}` and the `/v1/magpie/*` status endpoints. A GET on `/v1/responses` (a client opening Responses over a WebSocket) is answered 426, a plain one 405: Responses is relayed over HTTP only. Every route is wrapped in `counted`, `corsGuard`, `callerGuard`, `withCaller` and `keyLimited`. `corsGuard` (#1051) serves CORS only to the origins listed in Settings › Network › Web pages (`settings.CORSOrigins`, cleaned to `scheme://host[:port]` by `settings.CleanOrigins`, which refuses a wildcard). For a listed origin it answers the preflight (204) and adds `Access-Control-Allow-Origin`, and every other request from it needs an enabled gateway key (`access.Authenticate`), even on loopback, or gets a 401. A request with any other Origin, or none, passes through with no CORS headers, as before. | [`gateway.go`](../../internal/gateway/gateway.go), [`cors.go`](../../internal/gateway/cors.go), [`internal/settings/origins.go`](../../internal/settings/origins.go) |
 | Model resolution | `serve` resolves the model the agent asked for: Claude tier stand-ins, a routing group (`provider.GroupFor`), auto stand-ins, then `provider.Resolve`. An unknown model gets a 404 naming why: a switched-off provider, a disabled group or an empty group. | [`gateway.go`](../../internal/gateway/gateway.go), [`internal/provider/group.go`](../../internal/provider/group.go) |
 | Candidates | `plan` lists one provider's candidates: one per key or account on, then each `Fallback` model, with resting ones last (`restLast`). `planGroup` and `planLevel` weigh a group's members together. A nested group plans by its own routing (#576). A member's own fallbacks are not the group's. | [`fallback.go`](../../internal/gateway/fallback.go) |
 | Order of keys and accounts | `Routing`: smart (""), `order`, `rotate`, `usage` (least used, with an `usageHalfLife` of 1h), `pace` or `weight` (`weightedFirst`). Smart, `usage` and `pace` weigh a subscription by its allowance (`allowances`), and a key by its own usage windows when magpie reads them (`keyAllowance`: a sub2api key given a 5-hour, day or 7-day limit, or a key bought as a plan, such as Kimi Code's or a GLM Coding Plan's); any other key has none. A lone key or account is weighed against nobody, but what it has left is still read into the trace (`weighRouted`), so the Routing page shows it as it does for several (#1016); all but used up, it keeps its conversation rather than being said to move (`affine`). A failure rests a candidate (`failure`, `failureOf`). | [`routing.go`](../../internal/gateway/routing.go), [`weighted.go`](../../internal/gateway/weighted.go), [`internal/provider/routing.go`](../../internal/provider/routing.go) |
diff --git a/internal/gateway/cors.go b/internal/gateway/cors.go
new file mode 100644
index 00000000..b4982d85
--- /dev/null
+++ b/internal/gateway/cors.go
@@ -0,0 +1,78 @@
+package gateway
+
+import (
+	"net/http"
+	"slices"
+	"strings"
+
+	"github.com/yetone/magpie/internal/access"
+	"github.com/yetone/magpie/internal/provider"
+	"github.com/yetone/magpie/internal/settings"
+)
+
+// corsGuard lets the web pages the user listed in Settings › Gateway
+// (settings.CORSOrigins, #1051) call the gateway from a browser: their
+// preflight is answered, and their calls get the headers that let the page
+// read the reply. Such a call carries an enabled gateway key — a page is
+// not an agent the user started, and on loopback a call needs no key, so
+// without one any script served at that origin (another dev server on
+// the same port) could spend the user's subscriptions. A page not listed
+// gets no CORS headers, as before, and a request with no Origin (every
+// agent's) passes untouched.
+func corsGuard(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		origin := r.Header.Get("Origin")
+		if origin == "" || !corsAllowed(origin) {
+			next.ServeHTTP(w, r)
+			return
+		}
+		h := w.Header()
+		h.Set("Access-Control-Allow-Origin", origin)
+		h.Add("Vary", "Origin")
+		if r.Method == http.MethodOptions && r.Header.Get("Access-Control-Request-Method") != "" {
+			h.Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS")
+			if asked := corsHeaders(r.Header.Get("Access-Control-Request-Headers")); asked != "" {
+				h.Set("Access-Control-Allow-Headers", asked)
+			}
+			// Chrome asks before a public page reaches this computer
+			if r.Header.Get("Access-Control-Request-Private-Network") == "true" {
+				h.Set("Access-Control-Allow-Private-Network", "true")
+			}
+			h.Set("Access-Control-Max-Age", "600")
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+		if !slices.ContainsFunc(callerKeys(r), func(k string) bool { _, ok := access.Authenticate(k); return ok }) {
+			writeError(w, provider.Chat, http.StatusUnauthorized, "a web page calls magpie with a gateway key: create one in magpie's Gateway page and send it as Authorization: Bearer <key> (or x-api-key)")
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+// corsAllowed: origin is one the user listed.
+func corsAllowed(origin string) bool {
+	saved := settings.Load().CORSOrigins
+	if len(saved) == 0 {
+		return false
+	}
+	// as saved from Settings, or as written into settings.json by hand
+	list, _ := settings.CleanOrigins(saved)
+	o, err := settings.CleanOrigins([]string{origin})
+	return err == nil && len(o) == 1 && slices.Contains(list, o[0])
+}
+
+// corsHeaders is a preflight's Access-Control-Request-Headers as the
+// answer allows them: the header names asked for, nothing else.
+func corsHeaders(asked string) string {
+	var out []string
+	for _, f := range strings.Split(asked, ",") {
+		f = strings.TrimSpace(f)
+		if f != "" && !strings.ContainsFunc(f, func(c rune) bool {
+			return !(c == '-' || c == '_' || c >= '0' && c <= '9' || c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z')
+		}) {
+			out = append(out, f)
+		}
+	}
+	return strings.Join(out, ", ")
+}
diff --git a/internal/gateway/cors_test.go b/internal/gateway/cors_test.go
new file mode 100644
index 00000000..82f26ee0
--- /dev/null
+++ b/internal/gateway/cors_test.go
@@ -0,0 +1,119 @@
+package gateway
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/yetone/magpie/internal/access"
+	"github.com/yetone/magpie/internal/provider"
+	"github.com/yetone/magpie/internal/settings"
+)
+
+// A web page the user listed in Settings (#1051, SkyAerope: a preflight
+// from http://localhost:3000 for /v1/models was answered 404 with no CORS
+// headers) has its preflight answered and reads the reply, its calls with
+// a gateway key; a page not listed gets no CORS headers, as before, nor
+// does any page while none is listed; agents, which send no Origin, are
+// untouched.
+func TestCORSOrigins(t *testing.T) {
+	fresh(t)
+	up := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		io.WriteString(w, `{"choices":[{"message":{"role":"assistant","content":"ok"},"finish_reason":"stop"}],"usage":{"prompt_tokens":3,"completion_tokens":1}}`)
+	}))
+	defer up.Close()
+	if err := provider.Save(provider.Provider{ID: "plan", Name: "Plan", Key: "upstream-secret", Chat: up.URL + "/v1", Models: []string{"m1"}}); err != nil {
+		t.Fatal(err)
+	}
+	secret, err := access.Update("add-key", access.Change{Name: "Web app"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	h := New().Handler()
+	// from this computer, as a browser on it calls 127.0.0.1:3425
+	do := func(method, path, origin, key string, hdr map[string]string) *httptest.ResponseRecorder {
+		t.Helper()
+		var body io.Reader
+		if method == "POST" {
+			body = strings.NewReader(chatReq)
+		}
+		r := httptest.NewRequest(method, path, body)
+		r.RemoteAddr = "127.0.0.1:50123"
+		if origin != "" {
+			r.Header.Set("Origin", origin)
+		}
+		if key != "" {
+			r.Header.Set("Authorization", "Bearer "+key)
+		}
+		for k, v := range hdr {
+			r.Header.Set(k, v)
+		}
+		w := httptest.NewRecorder()
+		h.ServeHTTP(w, r)
+		return w
+	}
+	preflight := map[string]string{"Access-Control-Request-Method": "GET", "Access-Control-Request-Headers": "authorization, content-type"}
+
+	// none listed: the reporter's preflight, as before
+	if w := do("OPTIONS", "/v1/models", "http://localhost:3000", "", preflight); w.Header().Get("Access-Control-Allow-Origin") != "" || w.Code == http.StatusNoContent {
+		t.Fatalf("none listed: %d %v", w.Code, w.Header())
+	}
+
+	s := settings.Load()
+	if s.CORSOrigins, err = settings.CleanOrigins([]string{"http://LOCALHOST:3000/", "https://app.example.com:443"}); err != nil {
+		t.Fatal(err)
+	}
+	if err := settings.Save(s); err != nil {
+		t.Fatal(err)
+	}
+
+	w := do("OPTIONS", "/v1/models", "http://localhost:3000", "", map[string]string{
+		"Access-Control-Request-Method": "POST", "Access-Control-Request-Headers": "authorization, content-type, x-app, bad name;",
+		"Access-Control-Request-Private-Network": "true"})
+	if w.Code != http.StatusNoContent || w.Header().Get("Access-Control-Allow-Origin") != "http://localhost:3000" ||
+		!strings.Contains(w.Header().Get("Access-Control-Allow-Methods"), "POST") ||
+		w.Header().Get("Access-Control-Allow-Headers") != "authorization, content-type, x-app" ||
+		w.Header().Get("Access-Control-Allow-Private-Network") != "true" || w.Header().Get("Vary") != "Origin" {
+		t.Fatalf("preflight: %d %v", w.Code, w.Header())
+	}
+	// the call itself, with a gateway key: answered and readable
+	if w := do("GET", "/v1/models", "http://localhost:3000", secret, nil); w.Code != 200 || w.Header().Get("Access-Control-Allow-Origin") != "http://localhost:3000" {
+		t.Fatalf("models: %d %v", w.Code, w.Header())
+	}
+	if w := do("POST", "/v1/chat/completions", "https://app.example.com", secret, nil); w.Code != 200 || w.Header().Get("Access-Control-Allow-Origin") != "https://app.example.com" || !strings.Contains(w.Body.String(), "ok") {
+		t.Fatalf("chat: %d %v %s", w.Code, w.Header(), w.Body)
+	}
+	// without one, or with a key that isn't a gateway key, it is refused —
+	// readably, so the page can say why
+	for _, key := range []string{"", "magpie", "sk-magpie-not-a-key"} {
+		w := do("POST", "/v1/chat/completions", "http://localhost:3000", key, nil)
+		if w.Code != http.StatusUnauthorized || w.Header().Get("Access-Control-Allow-Origin") != "http://localhost:3000" || !strings.Contains(w.Body.String(), "gateway key") {
+			t.Errorf("key %q: %d %v %s", key, w.Code, w.Header(), w.Body)
+		}
+	}
+	// a key turned off is no key
+	keys, _ := access.List()
+	access.Update("off-key", access.Change{Key: keys[len(keys)-1].ID})
+	if w := do("GET", "/v1/models", "http://localhost:3000", secret, nil); w.Code != http.StatusUnauthorized {
+		t.Errorf("a key turned off: %d", w.Code)
+	}
+	access.Update("on-key", access.Change{Key: keys[len(keys)-1].ID})
+
+	// another page: no CORS headers, whatever it sends; a port or scheme
+	// apart is another origin
+	for _, o := range []string{"http://localhost:3001", "https://localhost:3000", "http://evil.example", "null"} {
+		if w := do("OPTIONS", "/v1/models", o, "", preflight); w.Header().Get("Access-Control-Allow-Origin") != "" || w.Code == http.StatusNoContent {
+			t.Errorf("%s preflight: %d %v", o, w.Code, w.Header())
+		}
+		if w := do("GET", "/v1/models", o, secret, nil); w.Header().Get("Access-Control-Allow-Origin") != "" {
+			t.Errorf("%s: %v", o, w.Header())
+		}
+	}
+	// an agent: no Origin, no key, as before
+	if w := do("POST", "/v1/chat/completions", "", "", nil); w.Code != 200 || w.Header().Get("Access-Control-Allow-Origin") != "" {
+		t.Fatalf("agent: %d %v", w.Code, w.Header())
+	}
+}
diff --git a/internal/gateway/gateway.go b/internal/gateway/gateway.go
index d84f179b..cb3691a5 100644
--- a/internal/gateway/gateway.go
+++ b/internal/gateway/gateway.go
@@ -527,7 +527,7 @@ func (s *Server) Handler() http.Handler {
 	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		writeError(w, provider.Chat, http.StatusNotFound, "magpie serves /v1/chat/completions, /v1/responses, /v1/messages, /v1/systemone, /v1/images/generations, /v1/images/edits, /v1/videos, /v1/embeddings, /v1/rerank and /v1beta/models/*")
 	})
-	return s.counted(callerGuard(withCaller(keyLimited(mux))))
+	return s.counted(corsGuard(callerGuard(withCaller(keyLimited(mux)))))
 }
 
 // responsesOverHTTP answers a GET on /v1/responses, which is how a client
diff --git a/internal/gui/api.go b/internal/gui/api.go
index 7ba61472..601521c6 100644
--- a/internal/gui/api.go
+++ b/internal/gui/api.go
@@ -994,6 +994,7 @@ func Handler(w Windows, gw *gateway.Server) http.Handler {
 		in.LAN, in.LANKey = cur.LAN, cur.LANKey
 		in.LANKeyID = cur.LANKeyID
 		in.Port = cur.Port                               // set on its own (port below), which moves the gateway
+		in.CORSOrigins = cur.CORSOrigins                 // set on its own (cors below)
 		in.GitHubToken = cur.GitHubToken                 // set on its own (github-token below), never sent to the page
 		in.RequestArchive = cur.RequestArchive           // the Gateway page's, set on its own
 		in.RequestArchiveMaxMB = cur.RequestArchiveMaxMB // in settings.json only
@@ -1465,6 +1466,27 @@ func Handler(w Windows, gw *gateway.Server) http.Handler {
 		}
 		writeJSON(rw, settingsState())
 	})
+	// the web pages that may call the gateway from a browser (#1051), as
+	// their origins; none takes them all away
+	mux.HandleFunc("POST /api/settings/cors", func(rw http.ResponseWriter, r *http.Request) {
+		var in struct{ Origins []string }
+		if err := json.NewDecoder(r.Body).Decode(&in); err != nil {
+			fail(rw, err)
+			return
+		}
+		origins, err := settings.CleanOrigins(in.Origins)
+		if err != nil {
+			fail(rw, err)
+			return
+		}
+		s := settings.Load()
+		s.CORSOrigins = origins
+		if err := settings.Save(s); err != nil {
+			fail(rw, err)
+			return
+		}
+		writeJSON(rw, settingsState())
+	})
 	// the gateway's port (Magic_zero on Discord), set on its own: it moves
 	// the gateway and every agent connected to it
 	mux.HandleFunc("POST /api/settings/port", func(rw http.ResponseWriter, r *http.Request) {
diff --git a/internal/gui/assets/app.js b/internal/gui/assets/app.js
index e9f29fa0..0f150609 100644
--- a/internal/gui/assets/app.js
+++ b/internal/gui/assets/app.js
@@ -17626,6 +17626,7 @@ function renderSettings() {
   renderOTel(s, keep);
   renderPort(s);
   renderLAN(s);
+  renderCORS(s);
   renderSync();
 
   const about = $("#about");
@@ -19026,6 +19027,60 @@ function renderPort(s) {
   box.replaceChildren(r); // swapped whole: the list is never laid out empty
 }
 
+// renderCORS: the web pages whose scripts may call the gateway from a
+// browser (#1051), by origin — a row to add one, and one row each to take
+// it away. A page listed calls with a gateway key; none listed, no page
+// can read what the gateway answers, as before.
+let corsDraft = { value: "", err: "" };
+// corsSays is the gateway's word on an origin it didn't take, in the
+// page's language
+function corsSays(m) {
+  if (/wildcard/.test(m)) return t("Name each origin: a wildcard would let every web page use magpie");
+  if (/is not an origin/.test(m)) return t("Write an origin as http://localhost:3000 or https://app.example.com");
+  return t(m);
+}
+function renderCORS(s) {
+  const box = $("#corsList");
+  box.replaceChildren();
+  const origins = s.corsOrigins || [];
+  const d = corsDraft;
+  const set = (next, done) => writingPrefs(api("settings/cors", { origins: next }))
+    .then((ns) => { prefs = ns; d.err = ""; done?.(); renderSettings(); status(t("Saved"), "ok", 1500); })
+    .catch((e) => { d.err = corsSays(e.message); status(d.err, "err"); renderSettings(); });
+  const field = input(d.value, "http://localhost:3000");
+  field.className = "words rule-match";
+  field.setAttribute("aria-label", t("Web page origin"));
+  field.autocomplete = "off";
+  field.spellcheck = false;
+  const add = el("button", "text", t("Add"));
+  add.onclick = () => {
+    d.value = field.value.trim();
+    if (!d.value) return field.focus();
+    set([...origins, d.value], () => { corsDraft = { value: "", err: "" }; });
+  };
+  field.oninput = () => { d.value = field.value; };
+  field.onkeydown = (e) => { e.stopPropagation(); if (e.key === "Enter") add.onclick(); };
+  const r = el("div", "row pref rule-row");
+  const who = el("div", "who");
+  who.append(el("div", "name", t("Web pages that may call magpie")),
+    el("div", "sub" + (d.err ? " err" : ""), d.err || t("Scripts on these origins can call the gateway from a browser, each request with a gateway key from Gateway. Any other page gets no CORS headers")));
+  const val = el("div", "val rule-add");
+  val.append(field, add);
+  r.append(who, val);
+  box.append(r);
+  for (const o of origins) {
+    const row = el("div", "row pref");
+    const w = el("div", "who");
+    w.append(el("div", "name", o));
+    const x = el("button", "text", t("Remove"));
+    x.onclick = () => set(origins.filter((v) => v !== o));
+    const v = el("div", "val");
+    v.append(x);
+    row.append(w, v);
+    box.append(row);
+  }
+}
+
 // renderLAN: the gateway shared on the local network, for agents on other
 // machines. Gateway keys and connection examples live together in Gateway.
 let lanSelectedURL = "", lanProtocol = "openai";
diff --git a/internal/gui/assets/i18n.js b/internal/gui/assets/i18n.js
index b464aab9..3726d565 100644
--- a/internal/gui/assets/i18n.js
+++ b/internal/gui/assets/i18n.js
@@ -1445,6 +1445,12 @@ const I18N = {
     "Edit as JSON": "以 JSON 编辑",
     "Collapse to one line": "折叠为单行",
     "Remove": "移除",
+    "Web pages": "网页",
+    "Web page origin": "网页来源",
+    "Web pages that may call magpie": "允许调用 magpie 的网页",
+    "Scripts on these origins can call the gateway from a browser, each request with a gateway key from Gateway. Any other page gets no CORS headers": "这些来源的网页脚本可以在浏览器中调用网关，每个请求需带上「网关」页的网关密钥。其他网页不会得到 CORS 响应头",
+    "Name each origin: a wildcard would let every web page use magpie": "请逐个填写来源：通配符会让任何网页都能使用 magpie",
+    "Write an origin as http://localhost:3000 or https://app.example.com": "来源格式如 http://localhost:3000 或 https://app.example.com",
     "{name} removed": "已移除 {name}",
     "Add": "添加",
     "{name} added": "已添加 {name}",
@@ -4998,6 +5004,12 @@ const I18N = {
     "Edit as JSON": "JSON で編集",
     "Collapse to one line": "1行に折りたたむ",
     "Remove": "削除",
+    "Web pages": "Web ページ",
+    "Web page origin": "Web ページのオリジン",
+    "Web pages that may call magpie": "magpie を呼び出せる Web ページ",
+    "Scripts on these origins can call the gateway from a browser, each request with a gateway key from Gateway. Any other page gets no CORS headers": "これらのオリジンのスクリプトはブラウザからゲートウェイを呼び出せます。各リクエストには「ゲートウェイ」ページのゲートウェイキーが必要です。ほかのページには CORS ヘッダーを返しません",
+    "Name each origin: a wildcard would let every web page use magpie": "オリジンは一つずつ指定してください。ワイルドカードではどの Web ページでも magpie を使えてしまいます",
+    "Write an origin as http://localhost:3000 or https://app.example.com": "オリジンは http://localhost:3000 や https://app.example.com の形式で入力してください",
     "{name} removed": "{name} を削除しました",
     "Add": "追加",
     "{name} added": "{name} を追加しました",
@@ -8563,6 +8575,12 @@ const I18N = {
     "Edit as JSON": "Als JSON bearbeiten",
     "Collapse to one line": "Auf eine Zeile reduzieren",
     "Remove": "Entfernen",
+    "Web pages": "Webseiten",
+    "Web page origin": "Herkunft der Webseite",
+    "Web pages that may call magpie": "Webseiten, die magpie aufrufen dürfen",
+    "Scripts on these origins can call the gateway from a browser, each request with a gateway key from Gateway. Any other page gets no CORS headers": "Skripte dieser Herkünfte können das Gateway aus dem Browser aufrufen, jede Anfrage mit einem Gateway-Schlüssel aus „Gateway“. Andere Seiten erhalten keine CORS-Header",
+    "Name each origin: a wildcard would let every web page use magpie": "Jede Herkunft einzeln angeben: Ein Platzhalter ließe jede Webseite magpie nutzen",
+    "Write an origin as http://localhost:3000 or https://app.example.com": "Eine Herkunft wird wie http://localhost:3000 oder https://app.example.com geschrieben",
     "{name} removed": "{name} entfernt",
     "Add": "Hinzufügen",
     "{name} added": "{name} hinzugefügt",
diff --git a/internal/gui/assets/index.html b/internal/gui/assets/index.html
index ee73c0d0..ad4419dc 100644
--- a/internal/gui/assets/index.html
+++ b/internal/gui/assets/index.html
@@ -437,6 +437,8 @@
     <div class="list prefs" id="portList"></div>
     <div class="row-head"><span class="label" data-t>Local network</span></div>
     <div class="list prefs" id="lanList"></div>
+    <div class="row-head"><span class="label" data-t>Web pages</span></div>
+    <div class="list prefs" id="corsList"></div>
   </section>
   <section class="set-page" id="setPage-models" role="tabpanel" aria-labelledby="setTab-models">
     <div class="row-head"><span class="label" data-t>Images</span></div>
diff --git a/internal/gui/cors_settings_test.go b/internal/gui/cors_settings_test.go
new file mode 100644
index 00000000..f6a5f53c
--- /dev/null
+++ b/internal/gui/cors_settings_test.go
@@ -0,0 +1,45 @@
+package gui
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"slices"
+	"strings"
+	"testing"
+
+	"github.com/yetone/magpie/internal/settings"
+)
+
+// The web pages that may call the gateway (#1051) are saved as origins,
+// a wildcard or a URL that isn't one is refused with the list left as it
+// was, and a save of the rest of the Settings page leaves them alone.
+func TestCORSOriginsSetting(t *testing.T) {
+	h := t.TempDir()
+	t.Setenv("HOME", h)
+	t.Setenv("USERPROFILE", h)
+	t.Setenv("XDG_CONFIG_HOME", filepath.Join(h, ".config"))
+	t.Setenv("XDG_CACHE_HOME", filepath.Join(h, ".cache"))
+	srv := Handler(nil, nil)
+	post := func(path, body string) *httptest.ResponseRecorder {
+		rec := httptest.NewRecorder()
+		srv.ServeHTTP(rec, httptest.NewRequest("POST", path, strings.NewReader(body)))
+		return rec
+	}
+	rec := post("/api/settings/cors", `{"origins":["http://LocalHost:3000/","https://app.example.com:443"]}`)
+	want := []string{"http://localhost:3000", "https://app.example.com"}
+	if rec.Code != http.StatusOK || !slices.Equal(settings.Load().CORSOrigins, want) || !strings.Contains(rec.Body.String(), `"corsOrigins":["http://localhost:3000","https://app.example.com"]`) {
+		t.Fatalf("%d %s, saved %v", rec.Code, rec.Body, settings.Load().CORSOrigins)
+	}
+	for _, bad := range []string{`["*"]`, `["http://localhost:3000","localhost:4000"]`, `["https://app.example.com/v1"]`} {
+		if rec := post("/api/settings/cors", `{"origins":`+bad+`}`); rec.Code == http.StatusOK || !slices.Equal(settings.Load().CORSOrigins, want) {
+			t.Errorf("%s: %d, saved %v", bad, rec.Code, settings.Load().CORSOrigins)
+		}
+	}
+	if rec := post("/api/settings", `{"theme":"dark","lang":"en"}`); rec.Code != http.StatusOK || !slices.Equal(settings.Load().CORSOrigins, want) {
+		t.Fatalf("the Settings page's save changed the origins: %d %v", rec.Code, settings.Load().CORSOrigins)
+	}
+	if rec := post("/api/settings/cors", `{"origins":[]}`); rec.Code != http.StatusOK || len(settings.Load().CORSOrigins) != 0 {
+		t.Fatalf("emptied: %d %v", rec.Code, settings.Load().CORSOrigins)
+	}
+}
diff --git a/internal/gui/settings_keep_test.go b/internal/gui/settings_keep_test.go
index 586222fd..128a2e8e 100644
--- a/internal/gui/settings_keep_test.go
+++ b/internal/gui/settings_keep_test.go
@@ -131,6 +131,7 @@ func TestSettingsSaveKeepsWhatItDoesNotSend(t *testing.T) {
 		LANKey:              "sk-lan",
 		LANKeyID:            "lan-key-id",
 		Port:                3591,
+		CORSOrigins:         []string{"http://localhost:3000"},
 		GitHubToken:         "ghp_kept",
 		RequestArchive:      true,
 		RequestArchiveMaxMB: 64,
diff --git a/internal/gui/tests/cors-origins.test.cjs b/internal/gui/tests/cors-origins.test.cjs
new file mode 100644
index 00000000..08d36b9b
--- /dev/null
+++ b/internal/gui/tests/cors-origins.test.cjs
@@ -0,0 +1,194 @@
+// Run with Node's test runner and Playwright on the module path; see README.md.
+// Web pages that may call magpie (#1051, SkyAerope: a page on
+// http://localhost:3000 couldn't read the gateway's answers): Settings ›
+// Network lists them by origin. One is added from a field and its Add
+// button (or Enter), saved as the gateway cleaned it, and taken away with
+// its Remove; a wildcard or a URL that isn't an origin is refused, said in
+// the page's language, and nothing is saved. At a 440px panel every row
+// fits, and no click moves the page. English and Chinese, Chromium and
+// WebKit; no backend, the API is faked here.
+const assert = require("node:assert/strict");
+const fs = require("node:fs/promises");
+const path = require("node:path");
+const { test } = require("node:test");
+const { chromium, webkit } = require("playwright");
+
+const assets = path.resolve(__dirname, "../assets");
+
+function settingsPayload(over) {
+  return {
+    theme: "light", lang: "en", tray: "panel", quotaLeft: false, currency: "usd",
+    dock: false, dockWindow: false, proxy: "", redact: false, redactPersonal: false, redactWords: [],
+    codexWarmup: "", claudeWarmup: "", codexWarmAt: "", claudeWarmAt: "", workbuddyCheckin: false, noStats: false,
+    trayUsage: "", trayUsageEvery: 3, vision: "", imageGen: "",
+    version: "0.1.400", dir: "/config/magpie", gateway: "http://127.0.0.1:3425",
+    proxyNow: "none", proxySource: "none", login: false,
+    visionModels: [], imageGenModels: [], workbuddyCheckins: [],
+    lan: false, lanURLs: [],
+    fx: { rate: 7.2, at: new Date().toISOString(), stale: false },
+    ...over,
+  };
+}
+
+// what the gateway does with a list: cleans it, or refuses it as
+// internal/settings/origins.go does
+function clean(list) {
+  const out = [];
+  for (const raw of list) {
+    if (raw.includes("*")) return { error: `"${raw}": name each origin; a wildcard would let every web page use magpie` };
+    let u;
+    try { u = new URL(raw); } catch { u = null; }
+    if (!u || !/^https?:$/.test(u.protocol) || (u.pathname !== "/" && u.pathname !== "")) return { error: `"${raw}" is not an origin: write it as http://localhost:3000 or https://app.example.com` };
+    if (!out.includes(u.origin)) out.push(u.origin);
+  }
+  return { origins: out };
+}
+
+function server(lang, posts) {
+  const s = settingsPayload({ lang, corsOrigins: [] });
+  return async (route) => {
+    const url = new URL(route.request().url());
+    const json = (data, status = 200) => route.fulfill({ json: data, status });
+    if (url.pathname === "/boot.js") return route.fulfill({ contentType: "text/javascript", body: `window.bootPrefs = {lang:"${lang}",theme:"light"};` });
+    if (url.pathname === "/wails/runtime.js") return route.fulfill({ contentType: "text/javascript", body: "export const Window = {};" });
+    if (url.pathname === "/api/state") return json({ agents: [], profiles: [], settings: { lang, theme: "light" }, fx: s.fx });
+    if (url.pathname === "/api/settings") return json(s);
+    if (url.pathname === "/api/settings/cors") {
+      const body = route.request().postDataJSON();
+      posts.push(body.origins);
+      const c = clean(body.origins);
+      if (c.error) return json({ error: c.error }, 400);
+      s.corsOrigins = c.origins;
+      return json(s);
+    }
+    if (url.pathname === "/api/plugins") return json({ plugins: [] });
+    if (url.pathname === "/api/usage/quotas") return json([]);
+    if (url.pathname === "/api/groups") return json({ groups: [], models: [] });
+    if (url.pathname.startsWith("/api/")) return json({});
+    const file = path.join(assets, url.pathname === "/" ? "index.html" : url.pathname);
+    const contentType = { ".html": "text/html", ".js": "text/javascript", ".css": "text/css", ".svg": "image/svg+xml", ".png": "image/png" }[path.extname(file)];
+    await route.fulfill({ body: await fs.readFile(file), contentType });
+  };
+}
+
+const words = {
+  en: {
+    head: "Web pages", name: "Web pages that may call magpie", add: "Add", remove: "Remove",
+    sub: "Scripts on these origins can call the gateway from a browser, each request with a gateway key from Gateway. Any other page gets no CORS headers",
+    wildcard: "Name each origin: a wildcard would let every web page use magpie",
+    notOrigin: "Write an origin as http://localhost:3000 or https://app.example.com",
+  },
+  zh: {
+    head: "网页", name: "允许调用 magpie 的网页", add: "添加", remove: "移除",
+    sub: null, wildcard: null, notOrigin: null, // read from i18n.js below
+  },
+};
+
+for (const engine of (process.env.BROWSER ? [process.env.BROWSER] : ["chromium", "webkit"])) {
+  test(engine + ": web pages that may call magpie are listed by origin (#1051)", async (t) => {
+    assert(["chromium", "webkit"].includes(engine), "BROWSER must be chromium or webkit");
+    const browser = await (engine === "webkit" ? webkit.launch() : chromium.launch({ channel: "chromium" }));
+    t.after(() => browser.close());
+
+    for (const lang of ["en", "zh"]) {
+      await t.test(lang, async () => {
+        const posts = [];
+        const page = await (await browser.newContext({ viewport: { width: 440, height: 520 }, reducedMotion: "reduce" })).newPage();
+        page.setDefaultTimeout(5000);
+        const errors = [];
+        page.on("pageerror", (e) => errors.push(e.message));
+        await page.route("**/*", server(lang, posts));
+        await page.goto("http://127.0.0.1:4999/?view=settings&tab=network");
+        const box = page.locator("#corsList");
+        await box.locator(".rule-row").waitFor();
+        const tr = (s) => page.evaluate((s) => t(s), s);
+        const w = { ...words[lang] };
+        for (const k of ["head", "name", "add", "remove", "sub", "wildcard", "notOrigin"]) {
+          const en = words.en[k];
+          const got = await tr(en);
+          if (lang !== "en") assert.notEqual(got, en, `"${en}" has no ${lang} translation`);
+          if (w[k] === null) w[k] = got;
+          else assert.equal(got, w[k]);
+        }
+        const head = box.locator("xpath=preceding-sibling::div[contains(@class,'row-head')][1]");
+        assert.equal((await head.textContent()).trim(), w.head);
+        const row = box.locator(".rule-row");
+        assert.equal((await row.locator(".name").textContent()).trim(), w.name);
+        assert.equal((await row.locator(".sub").textContent()).trim(), w.sub);
+
+        // every row fits the panel: nothing cut, nothing past the edge
+        const fits = async () => {
+          const bad = await box.evaluate((b) => {
+            const out = [];
+            const right = b.getBoundingClientRect().right + 0.5;
+            for (const e of b.querySelectorAll(".row, input, button, .name, .sub")) {
+              const r = e.getBoundingClientRect();
+              if (r.right > right || r.width === 0) out.push(e.className + " " + r.right + ">" + right);
+              if (e.matches("button, .name") && e.scrollWidth > e.clientWidth + 1) out.push("cut: " + e.textContent);
+            }
+            if (document.documentElement.scrollWidth > innerWidth) out.push("page scrolls sideways");
+            return out;
+          });
+          assert.deepEqual(bad, []);
+        };
+        await fits();
+        const field = row.locator("input");
+        const add = row.locator("button", { hasText: w.add });
+        const view = page.locator("#view-settings");
+        // where the view rests once the frame is drawn
+        const scroll = () => view.evaluate((v) => new Promise((ok) => requestAnimationFrame(() => requestAnimationFrame(() => ok(v.scrollTop)))));
+        // scrolled with the wheel, as a reader would (a script's scroll is
+        // put back), until the field is well inside the view
+        await view.hover();
+        for (let i = 0; i < 40; i++) {
+          const r = await field.boundingBox();
+          if (r && r.y > 60 && r.y + r.height < 460 && (await scroll()) > 0) break;
+          await page.mouse.wheel(0, 120);
+          await page.waitForTimeout(30);
+        }
+        assert((await scroll()) > 0, "the settings must be scrolled to the field");
+
+        // added from the field: saved as the gateway cleaned it
+        await field.fill("http://LocalHost:3000/");
+        let before = await scroll();
+        await add.click();
+        await box.locator(".row:not(.rule-row) .name", { hasText: "http://localhost:3000" }).waitFor();
+        assert.deepEqual(posts.at(-1), ["http://LocalHost:3000/"]);
+        assert.equal(await row.locator("input").inputValue(), "", "the field is left empty for the next one");
+        assert.equal(await scroll(), before, "Add moved the page");
+        // and with Enter
+        await row.locator("input").fill("https://app.example.com");
+        await row.locator("input").press("Enter");
+        await box.locator(".row:not(.rule-row) .name", { hasText: "https://app.example.com" }).waitFor();
+        assert.deepEqual(posts.at(-1), ["http://localhost:3000", "https://app.example.com"]);
+        await fits();
+
+        // refused, in the page's language, and nothing saved
+        for (const [bad, says] of [["*", w.wildcard], ["localhost:4000/v1", w.notOrigin]]) {
+          await row.locator("input").fill(bad);
+          before = await scroll();
+          await row.locator("button", { hasText: w.add }).click();
+          await page.waitForFunction((s) => document.querySelector("#corsList .rule-row .sub.err")?.textContent.trim() === s, says);
+          assert.equal(await row.locator("input").inputValue(), bad, "what the user wrote stays, to be corrected");
+          assert.equal(await box.locator(".row:not(.rule-row)").count(), 2);
+          assert.equal(await scroll(), before, "a refusal moved the page");
+          await fits();
+        }
+
+        // taken away with its Remove
+        const gone = box.locator(".row:not(.rule-row)").filter({ hasText: "http://localhost:3000" });
+        before = await scroll();
+        await gone.locator("button", { hasText: w.remove }).click();
+        await page.waitForFunction(() => document.querySelectorAll("#corsList .row:not(.rule-row)").length === 1);
+        assert.deepEqual(posts.at(-1), ["https://app.example.com"]);
+        assert.equal(await scroll(), before, "Remove moved the page");
+        assert.equal((await row.locator(".sub").textContent()).trim(), w.sub, "a save clears the refusal");
+
+        const border = await box.locator(".row").first().evaluate((r) => getComputedStyle(r).borderLeftWidth);
+        assert(border === "0px" || border === "", "no left border accent: " + border);
+        assert.deepEqual(errors, []);
+        await page.context().close();
+      });
+    }
+  });
+}
diff --git a/internal/settings/origins.go b/internal/settings/origins.go
new file mode 100644
index 00000000..a7158091
--- /dev/null
+++ b/internal/settings/origins.go
@@ -0,0 +1,54 @@
+package settings
+
+import (
+	"fmt"
+	"net"
+	"net/url"
+	"slices"
+	"strings"
+)
+
+// CleanOrigins is the web origins a user typed for CORSOrigins, as a
+// browser's Origin header spells them: scheme://host[:port], lower-cased,
+// with no path and the scheme's default port left out. Only http and
+// https are origins; "*" is refused, since it would let every web page the
+// user opens spend their subscriptions.
+func CleanOrigins(in []string) ([]string, error) {
+	var out []string
+	for _, raw := range in {
+		o, err := cleanOrigin(raw)
+		if err != nil {
+			return nil, err
+		}
+		if o != "" && !slices.Contains(out, o) {
+			out = append(out, o)
+		}
+	}
+	return out, nil
+}
+
+func cleanOrigin(raw string) (string, error) {
+	raw = strings.TrimSpace(raw)
+	if raw == "" {
+		return "", nil
+	}
+	if strings.Contains(raw, "*") {
+		return "", fmt.Errorf("%q: name each origin; a wildcard would let every web page use magpie", raw)
+	}
+	u, err := url.Parse(strings.TrimSuffix(raw, "/"))
+	if err != nil || (u.Scheme != "http" && u.Scheme != "https") || u.Host == "" || u.User != nil ||
+		(u.Path != "" && u.Path != "/") || u.RawQuery != "" || u.Fragment != "" {
+		return "", fmt.Errorf("%q is not an origin: write it as http://localhost:3000 or https://app.example.com", raw)
+	}
+	host, port := strings.ToLower(u.Hostname()), u.Port()
+	if (u.Scheme == "http" && port == "80") || (u.Scheme == "https" && port == "443") {
+		port = ""
+	}
+	if strings.Contains(host, ":") {
+		host = "[" + host + "]"
+	}
+	if port != "" {
+		host = net.JoinHostPort(strings.Trim(host, "[]"), port)
+	}
+	return u.Scheme + "://" + host, nil
+}
diff --git a/internal/settings/origins_test.go b/internal/settings/origins_test.go
new file mode 100644
index 00000000..7ade3a72
--- /dev/null
+++ b/internal/settings/origins_test.go
@@ -0,0 +1,24 @@
+package settings
+
+import (
+	"strings"
+	"testing"
+)
+
+// An origin is saved as the browser sends it, whichever way the user wrote
+// it, and a wildcard or anything that is not an origin is refused (#1051).
+func TestCleanOrigins(t *testing.T) {
+	got, err := CleanOrigins([]string{" http://LocalHost:3000/ ", "https://a.example:443", "http://[::1]:8080", "http://a.example:80", "", "http://localhost:3000"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := []string{"http://localhost:3000", "https://a.example", "http://[::1]:8080", "http://a.example"}
+	if strings.Join(got, " ") != strings.Join(want, " ") {
+		t.Fatalf("%v, want %v", got, want)
+	}
+	for _, bad := range []string{"*", "https://*.example.com", "localhost:3000", "file:///x", "http://a.example/path", "http://u:p@a.example", "http://a.example?x=1", "null"} {
+		if _, err := CleanOrigins([]string{bad}); err == nil {
+			t.Errorf("%q taken", bad)
+		}
+	}
+}
diff --git a/internal/settings/settings.go b/internal/settings/settings.go
index c292da63..42372708 100644
--- a/internal/settings/settings.go
+++ b/internal/settings/settings.go
@@ -85,6 +85,12 @@ type Settings struct {
 	// named caller keys. LANKey is retained for older Magpie versions.
 	LAN    bool   `json:"lan,omitempty"`
 	LANKey string `json:"lanKey,omitempty"`
+	// CORSOrigins are the web pages (scheme://host[:port]) whose scripts
+	// may call the gateway from a browser (#1051): a preflight from one is
+	// answered, and its calls carry the CORS headers that let it read the
+	// reply, each with an enabled gateway key. None by default: a page
+	// gets no CORS headers, as before.
+	CORSOrigins []string `json:"corsOrigins,omitempty"`
 	// Port is the gateway's port on this computer, 0 for DefaultPort.
 	// MAGPIE_ADDR, where it is set, comes first (GatewayAddr).
 	Port int `json:"port,omitempty"`