Improve PushProcessor::getPushRuleGlobRegex (#4764)

* Improve PushProcessor::getPushRuleGlobRegex

Fix cache key not taking non-pattern parameters into account
Use lookarounds to ensure the word boundary isn't treated as part of the match

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Add tests

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

---------

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

spec/unit/pushprocessor.spec.ts

@@ -1,3 +1,19 @@
+/*
+Copyright 2025 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
 import * as utils from "../test-utils/test-utils";
 import { type IActionsObject, PushProcessor } from "../../src/pushprocessor";
 import {
@@ -1004,3 +1020,25 @@ describe("rewriteDefaultRules", () => {
         ]);
     });
 });
+
+describe("getPushRuleGlobRegex", () => {
+    it("should not confuse flags in cache", () => {
+        const pattern = "Test";
+        const regex1 = PushProcessor.getPushRuleGlobRegex(pattern, false, "i");
+        const regex2 = PushProcessor.getPushRuleGlobRegex(pattern, false, "g");
+        const regex3 = PushProcessor.getPushRuleGlobRegex(pattern, false, "i");
+
+        expect(regex1.flags).toBe("i");
+        expect(regex2.flags).toBe("g");
+
+        expect(regex1).not.toEqual(regex2);
+        expect(regex1).toEqual(regex3);
+    });
+
+    it("should not include word boundary in match", () => {
+        const pattern = "@room";
+        const regex = PushProcessor.getPushRuleGlobRegex(pattern, true);
+        const input = "Foo @room Bar";
+        expect(input.split(regex)).toEqual(["Foo ", "@room", " Bar"]);
+    });
+});