perf(security): bound regex input in filters and redaction

src/discord/monitor/exec-approvals.test.ts

@@ -318,6 +318,17 @@ describe("DiscordExecApprovalHandler.shouldHandle", () => {
     expect(handler.shouldHandle(createRequest({ sessionKey: `${"a".repeat(28)}!` }))).toBe(false);
   });
 
+  it("matches long session keys with tail-bounded regex checks", () => {
+    const handler = createHandler({
+      enabled: true,
+      approvers: ["123"],
+      sessionFilter: ["discord:tail$"],
+    });
+    expect(
+      handler.shouldHandle(createRequest({ sessionKey: `${"x".repeat(5000)}discord:tail` })),
+    ).toBe(true);
+  });
+
   it("filters by discord account when session store includes account", () => {
     writeStore({
       "agent:test-agent:discord:channel:999888777": {

src/discord/monitor/exec-approvals.ts

@@ -34,6 +34,7 @@ import { createDiscordClient, stripUndefinedFields } from "../send.shared.js";
 import { DiscordUiContainer } from "../ui.js";
 
 const EXEC_APPROVAL_KEY = "execapproval";
+const SESSION_FILTER_REGEX_MAX_INPUT = 2048;
 
 export type { ExecApprovalRequest, ExecApprovalResolved };
 
@@ -367,12 +368,28 @@ export class DiscordExecApprovalHandler {
       if (!session) {
         return false;
       }
+      const head = session.slice(0, SESSION_FILTER_REGEX_MAX_INPUT);
+      const tail =
+        session.length > SESSION_FILTER_REGEX_MAX_INPUT
+          ? session.slice(-SESSION_FILTER_REGEX_MAX_INPUT)
+          : "";
       const matches = config.sessionFilter.some((p) => {
         if (session.includes(p)) {
           return true;
         }
         const regex = compileSafeRegex(p);
-        return regex ? regex.test(session) : false;
+        if (!regex) {
+          return false;
+        }
+        regex.lastIndex = 0;
+        if (regex.test(head)) {
+          return true;
+        }
+        if (tail) {
+          regex.lastIndex = 0;
+          return regex.test(tail);
+        }
+        return false;
       });
       if (!matches) {
         return false;