diff --git a/src/action-routes.ts b/src/action-routes.ts
index 7a522ad..9766f96 100644
--- a/src/action-routes.ts
+++ b/src/action-routes.ts
@@ -2,6 +2,7 @@ import { Hono } from "hono";
 import { getUserOctokit } from "./github-oauth";
 import { findUserIdByToken } from "./token-store";
 import type { Env } from "./types";
+import { log } from "./log";
 
 function extractBearerToken(c: {
   req: { header: (name: string) => string | undefined };
@@ -11,6 +12,24 @@ function extractBearerToken(c: {
   return auth.slice(7);
 }
 
+function isNonEmptyString(value: unknown): value is string {
+  return typeof value === "string" && value.length > 0;
+}
+
+function isValidId(value: unknown): value is number {
+  return typeof value === "number" && Number.isFinite(value) && value > 0;
+}
+
+async function readJson(c: {
+  req: { json: <T>() => Promise<T> };
+}): Promise<Record<string, unknown> | null> {
+  try {
+    return (await c.req.json()) as Record<string, unknown>;
+  } catch {
+    return null;
+  }
+}
+
 export function createActionRoutes(): Hono<{ Bindings: Env }> {
   const app = new Hono<{ Bindings: Env }>();
 
@@ -20,21 +39,30 @@ export function createActionRoutes(): Hono<{ Bindings: Env }> {
     const userId = await findUserIdByToken(c.env.KV, token);
     if (!userId) return c.json({ error: "Invalid or expired token" }, 401);
 
-    const body = await c.req.json<{
-      owner: string;
-      repo: string;
-      issueNumber: number;
-      body: string;
-    }>();
+    const body = await readJson(c);
+    if (
+      !body ||
+      !isNonEmptyString(body.owner) ||
+      !isNonEmptyString(body.repo) ||
+      !isValidId(body.issueNumber) ||
+      !isNonEmptyString(body.body)
+    ) {
+      return c.json({ error: "Invalid request body" }, 400);
+    }
     const octokit = await getUserOctokit(userId, c.env.KV);
     if (!octokit) return c.json({ error: "Not authorized" }, 401);
 
-    await octokit.rest.issues.createComment({
-      owner: body.owner,
-      repo: body.repo,
-      issue_number: body.issueNumber,
-      body: body.body,
-    });
+    try {
+      await octokit.rest.issues.createComment({
+        owner: body.owner,
+        repo: body.repo,
+        issue_number: body.issueNumber,
+        body: body.body,
+      });
+    } catch (err) {
+      log.error({ err }, "Failed to create comment");
+      return c.json({ error: "GitHub API error" }, 500);
+    }
 
     return c.json({ ok: true });
   });
@@ -45,21 +73,33 @@ export function createActionRoutes(): Hono<{ Bindings: Env }> {
     const userId = await findUserIdByToken(c.env.KV, token);
     if (!userId) return c.json({ error: "Invalid or expired token" }, 401);
 
-    const body = await c.req.json<{
-      owner: string;
-      repo: string;
-      pullNumber: number;
-      method?: "merge" | "squash" | "rebase";
-    }>();
+    const body = await readJson(c);
+    if (
+      !body ||
+      !isNonEmptyString(body.owner) ||
+      !isNonEmptyString(body.repo) ||
+      !isValidId(body.pullNumber)
+    ) {
+      return c.json({ error: "Invalid request body" }, 400);
+    }
+    const method = body.method === undefined ? "squash" : body.method;
+    if (method !== "merge" && method !== "squash" && method !== "rebase") {
+      return c.json({ error: "Invalid request body" }, 400);
+    }
     const octokit = await getUserOctokit(userId, c.env.KV);
     if (!octokit) return c.json({ error: "Not authorized" }, 401);
 
-    await octokit.rest.pulls.merge({
-      owner: body.owner,
-      repo: body.repo,
-      pull_number: body.pullNumber,
-      merge_method: body.method ?? "squash",
-    });
+    try {
+      await octokit.rest.pulls.merge({
+        owner: body.owner,
+        repo: body.repo,
+        pull_number: body.pullNumber,
+        merge_method: method,
+      });
+    } catch (err) {
+      log.error({ err }, "Failed to merge pull request");
+      return c.json({ error: "GitHub API error" }, 500);
+    }
 
     return c.json({ ok: true });
   });
@@ -70,20 +110,29 @@ export function createActionRoutes(): Hono<{ Bindings: Env }> {
     const userId = await findUserIdByToken(c.env.KV, token);
     if (!userId) return c.json({ error: "Invalid or expired token" }, 401);
 
-    const body = await c.req.json<{
-      owner: string;
-      repo: string;
-      pullNumber: number;
-    }>();
+    const body = await readJson(c);
+    if (
+      !body ||
+      !isNonEmptyString(body.owner) ||
+      !isNonEmptyString(body.repo) ||
+      !isValidId(body.pullNumber)
+    ) {
+      return c.json({ error: "Invalid request body" }, 400);
+    }
     const octokit = await getUserOctokit(userId, c.env.KV);
     if (!octokit) return c.json({ error: "Not authorized" }, 401);
 
-    await octokit.rest.pulls.update({
-      owner: body.owner,
-      repo: body.repo,
-      pull_number: body.pullNumber,
-      state: "closed",
-    });
+    try {
+      await octokit.rest.pulls.update({
+        owner: body.owner,
+        repo: body.repo,
+        pull_number: body.pullNumber,
+        state: "closed",
+      });
+    } catch (err) {
+      log.error({ err }, "Failed to close pull request");
+      return c.json({ error: "GitHub API error" }, 500);
+    }
 
     return c.json({ ok: true });
   });
@@ -94,22 +143,40 @@ export function createActionRoutes(): Hono<{ Bindings: Env }> {
     const userId = await findUserIdByToken(c.env.KV, token);
     if (!userId) return c.json({ error: "Invalid or expired token" }, 401);
 
-    const body = await c.req.json<{
-      owner: string;
-      repo: string;
-      issueNumber: number;
-      reaction: string;
-    }>();
+    const body = await readJson(c);
+    const reactions = ["+1", "-1", "laugh", "confused", "heart", "hooray", "rocket", "eyes"] as const;
+    if (
+      !body ||
+      !isNonEmptyString(body.owner) ||
+      !isNonEmptyString(body.repo) ||
+      !isValidId(body.issueNumber) ||
+      !isNonEmptyString(body.reaction) ||
+      !(reactions as readonly string[]).includes(body.reaction)
+    ) {
+      return c.json({ error: "Invalid request body" }, 400);
+    }
     const octokit = await getUserOctokit(userId, c.env.KV);
     if (!octokit) return c.json({ error: "Not authorized" }, 401);
 
-    await octokit.rest.reactions.createForIssue({
-      owner: body.owner,
-      repo: body.repo,
-      issue_number: body.issueNumber,
-      content: body.reaction as
-        "+1" | "-1" | "laugh" | "confused" | "heart" | "hooray" | "rocket" | "eyes",
-    });
+    try {
+      await octokit.rest.reactions.createForIssue({
+        owner: body.owner,
+        repo: body.repo,
+        issue_number: body.issueNumber,
+        content: body.reaction as
+          | "+1"
+          | "-1"
+          | "laugh"
+          | "confused"
+          | "heart"
+          | "hooray"
+          | "rocket"
+          | "eyes",
+      });
+    } catch (err) {
+      log.error({ err }, "Failed to create reaction");
+      return c.json({ error: "GitHub API error" }, 500);
+    }
 
     return c.json({ ok: true });
   });
diff --git a/src/admin-session.ts b/src/admin-session.ts
index 8fb186f..2ed1aff 100644
--- a/src/admin-session.ts
+++ b/src/admin-session.ts
@@ -39,11 +39,11 @@ export async function createAdminSession(
 }
 
 export function adminCookie(sessionId: string): string {
-  return `${SESSION_COOKIE}=${sessionId}; Path=/; HttpOnly; SameSite=Lax; Max-Age=${SESSION_TTL}`;
+  return `${SESSION_COOKIE}=${sessionId}; Path=/; HttpOnly; Secure; SameSite=Lax; Max-Age=${SESSION_TTL}`;
 }
 
 export function clearAdminCookie(): string {
-  return `${SESSION_COOKIE}=; Path=/; HttpOnly; SameSite=Lax; Max-Age=0`;
+  return `${SESSION_COOKIE}=; Path=/; HttpOnly; Secure; SameSite=Lax; Max-Age=0`;
 }
 
 function parseCookies(header: string | undefined): Record<string, string> {
diff --git a/src/discord-gateway.ts b/src/discord-gateway.ts
index 4ded903..bee902b 100644
--- a/src/discord-gateway.ts
+++ b/src/discord-gateway.ts
@@ -205,12 +205,18 @@ export class DiscordGateway {
   }
 
   private handleMessage(data: string): void {
-    const msg = JSON.parse(data) as {
-      op: number;
-      d: unknown;
-      s: number | null;
-      t: string | null;
-    };
+    let msg: { op: number; d: unknown; s: number | null; t: string | null };
+    try {
+      msg = JSON.parse(data) as {
+        op: number;
+        d: unknown;
+        s: number | null;
+        t: string | null;
+      };
+    } catch {
+      log.warn("Gateway received malformed frame");
+      return;
+    }
 
     if (msg.s !== null) this.lastSequence = msg.s;
 
diff --git a/src/discord-rest.ts b/src/discord-rest.ts
index d940b91..17aacf5 100644
--- a/src/discord-rest.ts
+++ b/src/discord-rest.ts
@@ -33,6 +33,12 @@ export async function sendMessage(
 
       if (!res.ok) {
         const err = await res.text();
+        if (res.status >= 500) {
+          log.error({ status: res.status, err, attempt, channelId }, "Discord API 5xx");
+          if (attempt === 2) return { ok: false, error: err };
+          await new Promise((r) => setTimeout(r, 1000 * (attempt + 1)));
+          continue;
+        }
         log.error({ status: res.status, err, channelId }, "Discord API error");
         return { ok: false, error: err };
       }
diff --git a/src/discord.ts b/src/discord.ts
index d11432f..37ab3b2 100644
--- a/src/discord.ts
+++ b/src/discord.ts
@@ -53,39 +53,40 @@ export async function dispatchEvent(config: Config, event: WebhookEvent, env: En
   const matched = config.routes.filter((route) => matchRoute(route, event) && accepted(route));
   const anyRegularMatched = matched.some((route) => !route.fallback);
 
-  for (const route of matched) {
-    // A fallback route only fires when no regular route matched the event.
-    if (route.fallback && anyRegularMatched) continue;
+  const tasks = matched
+    .filter((route) => !(route.fallback && anyRegularMatched))
+    .map(async (route) => {
+      const target = route.target.threadId
+        ? `${route.target.channelId}/${route.target.threadId}`
+        : route.target.channelId;
 
-    const target = route.target.threadId
-      ? `${route.target.channelId}/${route.target.threadId}`
-      : route.target.channelId;
+      try {
+        const tr = trMap.get(route.lang ?? "en")!;
+        const message = formatEvent(route, event, tr);
+        await sendToChannel(route.target.channelId, message, env, route.target.threadId);
+        await recordSend(env.KV, {
+          ts: Date.now(),
+          routeId: route.id,
+          event: event.event,
+          repo: (event.payload.repository as { full_name?: string } | undefined)?.full_name,
+          target,
+          ok: true,
+        });
+      } catch (err) {
+        await recordSend(env.KV, {
+          ts: Date.now(),
+          routeId: route.id,
+          event: event.event,
+          repo: (event.payload.repository as { full_name?: string } | undefined)?.full_name,
+          target,
+          ok: false,
+          error: err instanceof Error ? err.message : String(err),
+        });
+        log.error({ routeId: route.id, err }, "Route failed");
+      }
+    });
 
-    try {
-      const tr = trMap.get(route.lang ?? "en")!;
-      const message = formatEvent(route, event, tr);
-      await sendToChannel(route.target.channelId, message, env, route.target.threadId);
-      await recordSend(env.KV, {
-        ts: Date.now(),
-        routeId: route.id,
-        event: event.event,
-        repo: (event.payload.repository as { full_name?: string } | undefined)?.full_name,
-        target,
-        ok: true,
-      });
-    } catch (err) {
-      await recordSend(env.KV, {
-        ts: Date.now(),
-        routeId: route.id,
-        event: event.event,
-        repo: (event.payload.repository as { full_name?: string } | undefined)?.full_name,
-        target,
-        ok: false,
-        error: err instanceof Error ? err.message : String(err),
-      });
-      log.error({ routeId: route.id, err }, "Route failed");
-    }
-  }
+  await Promise.allSettled(tasks);
 }
 
 async function sendToChannel(
diff --git a/src/oauth-routes.ts b/src/oauth-routes.ts
index 3ae2c77..167f60e 100644
--- a/src/oauth-routes.ts
+++ b/src/oauth-routes.ts
@@ -23,11 +23,19 @@ function generateRandomHex(length: number): string {
     .join("");
 }
 
+function safeRedirectPath(value: string | undefined): string {
+  if (!value) return "/";
+  if (!value.startsWith("/")) return "/";
+  if (value.startsWith("//")) return "/";
+  if (/^\/\\/.test(value)) return "/";
+  return value;
+}
+
 export function createOAuthRoutes(): Hono<{ Bindings: Env }> {
   const app = new Hono<{ Bindings: Env }>();
 
   app.get("/github", async (c) => {
-    const redirectTo = c.req.query("redirect") ?? "/";
+    const redirectTo = safeRedirectPath(c.req.query("redirect"));
     const state = generateRandomHex(16);
 
     const pending: PendingState = {
diff --git a/src/server.ts b/src/server.ts
index 8ef9cb6..b4a2955 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -7,6 +7,7 @@ import { createActionRoutes } from "./action-routes";
 import { createAdminRoutes } from "./admin-routes";
 import { createLegalRoutes } from "./legal-routes";
 import { createHomeRoutes } from "./home-routes";
+import { loadConfig } from "./config";
 import { log } from "./log";
 
 const MAX_BODY_SIZE = 1024 * 1024;
@@ -58,7 +59,6 @@ export function createServer(): Hono<{ Bindings: Env }> {
       await c.env.KV.put(`delivery:${delivery}`, "1", { expirationTtl: 300 });
     }
 
-    const { loadConfig } = await import("./config");
     const config = await loadConfig(c.env);
     const dispatch = dispatchEvent(config, event, c.env).catch((err) =>
       log.error(err, "Dispatch failed"),
diff --git a/src/webhook.ts b/src/webhook.ts
index 03cf02b..de79a95 100644
--- a/src/webhook.ts
+++ b/src/webhook.ts
@@ -1,6 +1,30 @@
 import type { WebhookEvent, Route, Filter } from "./types";
 
 const keyCache = new Map<string, CryptoKey>();
+const regexCache = new Map<string, RegExp>();
+const keywordBodyCache = new WeakMap<WebhookEvent, string>();
+const MAX_PATTERN_LENGTH = 200;
+
+function compileKeywordRegex(pattern: string): RegExp | null {
+  if (pattern.length > MAX_PATTERN_LENGTH) return null;
+  const cached = regexCache.get(pattern);
+  if (cached) return cached;
+  try {
+    const re = new RegExp(pattern, "i");
+    regexCache.set(pattern, re);
+    return re;
+  } catch {
+    return null;
+  }
+}
+
+function getKeywordBody(event: WebhookEvent): string {
+  const cached = keywordBodyCache.get(event);
+  if (cached !== undefined) return cached;
+  const body = JSON.stringify(event.payload).toLowerCase();
+  keywordBodyCache.set(event, body);
+  return body;
+}
 
 async function getHmacKey(secret: string): Promise<CryptoKey> {
   const cached = keyCache.get(secret);
@@ -109,15 +133,14 @@ function matchFilter(filter: Filter, event: WebhookEvent, keywordBody?: string):
       value = extractBranch(event);
       break;
     case "keyword": {
-      const body = keywordBody ?? JSON.stringify(event.payload).toLowerCase();
+      const body = keywordBody ?? getKeywordBody(event);
       const patterns = Array.isArray(filter.match) ? filter.match : [filter.match];
-      return patterns.some((p) => {
-        try {
-          return new RegExp(p, "i").test(body);
-        } catch {
-          return body.includes(p.toLowerCase());
-        }
+      const matches = patterns.some((p) => {
+        const re = compileKeywordRegex(p);
+        if (!re) return body.includes(p.toLowerCase());
+        return re.test(body);
       });
+      return filter.exclude ? !matches : matches;
     }
     default:
       return false;
@@ -145,6 +168,6 @@ export function eventOwners(event: WebhookEvent): string[] {
 export function matchRoute(route: Route, event: WebhookEvent): boolean {
   if (!route.enabled) return false;
   const hasKeyword = route.filters.some((f) => f.type === "keyword");
-  const keywordBody = hasKeyword ? JSON.stringify(event.payload).toLowerCase() : undefined;
+  const keywordBody = hasKeyword ? getKeywordBody(event) : undefined;
   return route.filters.every((f) => matchFilter(f, event, keywordBody));
 }