Specify type-safe jwtPayload

src/features/add-todo/addToDoPage.test.tsx

@@ -2,11 +2,29 @@ import { describe, expect, test } from "bun:test";
 import { createAppConfig } from "@shared/appConfig.ts";
 import { createAppConfigMiddleware } from "@shared/appConfigMiddleware.ts";
 import type { AppVariables } from "@shared/appVariables.ts";
+import {
+  createTodoJwtPayload,
+  type JwtPayload,
+} from "@shared/pageJwtMiddleware.ts";
 import { pageRoutes } from "@shared/pageRoutes.ts";
 import { Hono } from "hono";
 import { sign } from "hono/jwt";
 import { addToDoPage } from "./addToDoPage.tsx";
 
+const fixedPayloadDate = new Date("2024-01-01T00:00:00.000Z");
+const fixedIatInSeconds = Math.floor(fixedPayloadDate.getTime() / 1000);
+const fixedExpInSeconds = Math.floor(
+  new Date("2100-01-01T00:00:00.000Z").getTime() / 1000,
+);
+
+const createJwtPayload = (): JwtPayload => {
+  return {
+    ...createTodoJwtPayload("1234", "admin", "admin", fixedPayloadDate),
+    exp: fixedExpInSeconds,
+    iat: fixedIatInSeconds,
+  };
+};
+
 describe("addToDoPage", () => {
   test("redirects to login when JWT cookie is missing", async () => {
     const appConfig = createAppConfig({
@@ -28,11 +46,7 @@ describe("addToDoPage", () => {
     const appConfig = createAppConfig({
       JWT_SECRET: "12345678901234567890123456789012",
     });
-    const token = await sign(
-      { sub: "1234", preferred_username: "admin" },
-      appConfig.jwt.secret,
-      "HS256",
-    );
+    const token = await sign(createJwtPayload(), appConfig.jwt.secret, "HS256");
     const app = new Hono<{ Variables: AppVariables }>()
       .use("*", createAppConfigMiddleware(appConfig))
       .route(pageRoutes.ADD_TODO, addToDoPage);

src/features/add-todo/addToDoPage.tsx

@@ -1,14 +1,12 @@
 import type { AppVariables } from "@shared/appVariables.ts";
 import { Page } from "@shared/page.tsx";
 import { pageJwtMiddleware } from "@shared/pageJwtMiddleware.ts";
-import { getUsernameFromJwtPayload } from "@shared/utility.ts";
 import { Hono } from "hono";
 
 export const addToDoPage = new Hono<{ Variables: AppVariables }>()
   .use("/", pageJwtMiddleware)
   .get("/", (c) => {
-    const username = getUsernameFromJwtPayload(c.var.jwtPayload);
-
+    const username = c.var.validJwtPayload.preferred_username;
     return c.html(
       <Page type="authenticated" currentPath={c.req.path} username={username}>
         <h1>Add ToDo</h1>

src/features/home/homePage.test.tsx

@@ -2,11 +2,29 @@ import { describe, expect, test } from "bun:test";
 import { createAppConfig } from "@shared/appConfig.ts";
 import { createAppConfigMiddleware } from "@shared/appConfigMiddleware.ts";
 import type { AppVariables } from "@shared/appVariables.ts";
+import {
+  createTodoJwtPayload,
+  type JwtPayload,
+} from "@shared/pageJwtMiddleware.ts";
 import { pageRoutes } from "@shared/pageRoutes.ts";
 import { Hono } from "hono";
 import { sign } from "hono/jwt";
 import { homePage } from "./homePage.tsx";
 
+const fixedPayloadDate = new Date("2024-01-01T00:00:00.000Z");
+const fixedIatInSeconds = Math.floor(fixedPayloadDate.getTime() / 1000);
+const fixedExpInSeconds = Math.floor(
+  new Date("2100-01-01T00:00:00.000Z").getTime() / 1000,
+);
+
+const createJwtPayload = (): JwtPayload => {
+  return {
+    ...createTodoJwtPayload("1234", "admin", "admin", fixedPayloadDate),
+    exp: fixedExpInSeconds,
+    iat: fixedIatInSeconds,
+  };
+};
+
 describe("homePage", () => {
   test("redirects to login when JWT cookie is missing", async () => {
     const appConfig = createAppConfig({
@@ -26,11 +44,7 @@ describe("homePage", () => {
     const appConfig = createAppConfig({
       JWT_SECRET: "12345678901234567890123456789012",
     });
-    const token = await sign(
-      { sub: "1234", preferred_username: "admin" },
-      appConfig.jwt.secret,
-      "HS256",
-    );
+    const token = await sign(createJwtPayload(), appConfig.jwt.secret, "HS256");
     const app = new Hono<{ Variables: AppVariables }>()
       .use("*", createAppConfigMiddleware(appConfig))
       .route("/", homePage);

src/features/home/homePage.tsx

@@ -1,13 +1,12 @@
 import type { AppVariables } from "@shared/appVariables.ts";
 import { Page } from "@shared/page.tsx";
 import { pageJwtMiddleware } from "@shared/pageJwtMiddleware.ts";
-import { getUsernameFromJwtPayload } from "@shared/utility.ts";
 import { Hono } from "hono";
 
 export const homePage = new Hono<{ Variables: AppVariables }>()
   .use("/", pageJwtMiddleware)
   .get("/", (c) => {
-    const username = getUsernameFromJwtPayload(c.var.jwtPayload);
+    const username = c.var.validJwtPayload.preferred_username;
     return c.html(
       <Page type="authenticated" currentPath={c.req.path} username={username}>
         <h1>Home</h1>

src/features/login/loginApi.tsx

@@ -1,6 +1,7 @@
 import { zValidator } from "@hono/zod-validator";
 import type { AppVariables } from "@shared/appVariables.ts";
 import { sseRedirect } from "@shared/datastar.ts";
+import { createTodoJwtPayload } from "@shared/pageJwtMiddleware.ts";
 import { pageRoutes } from "@shared/pageRoutes.ts";
 import { getUserByUsername } from "@shared/user.ts";
 import { addDays } from "date-fns";
@@ -37,18 +38,13 @@ export const loginApi = new Hono<{ Variables: AppVariables }>().post(
     if (!isPasswordValid) {
       throw new HTTPException(401, { message: "Invalid credentials" });
     }
-    const token = await sign(
-      {
-        sub: user.id,
-        preferred_username: user.username,
-        role: "admin",
-        iss: "todo-app",
-        exp: Math.floor(addDays(now, 1).getTime() / 1000),
-        iat: Math.floor(now.getTime() / 1000),
-      },
-      appConfig.jwt.secret,
-      "HS256",
+    const jwtPayload = createTodoJwtPayload(
+      user.id,
+      user.username,
+      "admin",
+      now,
     );
+    const token = await sign(jwtPayload, appConfig.jwt.secret, "HS256");
     setCookie(c, appConfig.jwt.cookieName, token, {
       httpOnly: true,
       sameSite: "Strict",

src/shared/appVariables.ts

@@ -1,10 +1,12 @@
-import type { JwtVariables } from "hono/jwt";
 import type { Logger } from "winston";
 import type { AppConfig } from "./appConfig.ts";
 import type { Clock } from "./clock.ts";
+import type { JwtPayload } from "./pageJwtMiddleware.ts";
 
 export type AppVariables = {
   clock: Clock;
   appConfig: AppConfig;
   logger: Logger;
-} & JwtVariables;
+  jwtPayload: unknown;
+  validJwtPayload: JwtPayload;
+};

src/shared/pageJwtMiddleware.test.ts

@@ -1,12 +1,32 @@
 import { describe, expect, test } from "bun:test";
-import type { AppVariables } from "@shared/appVariables.ts";
+import { addDays } from "date-fns";
 import { Hono } from "hono";
 import { sign } from "hono/jwt";
 import { createAppConfig } from "./appConfig.ts";
 import { createAppConfigMiddleware } from "./appConfigMiddleware.ts";
-import { pageJwtMiddleware } from "./pageJwtMiddleware.ts";
+import type { AppVariables } from "./appVariables.ts";
+import {
+  createTodoJwtPayload,
+  type JwtPayload,
+  pageJwtMiddleware,
+} from "./pageJwtMiddleware.ts";
 import { pageRoutes } from "./pageRoutes.ts";
 
+const fixedPayloadDate = new Date("2024-01-01T00:00:00.000Z");
+const fixedIatInSeconds = Math.floor(fixedPayloadDate.getTime() / 1000);
+const fixedExpInSeconds = Math.floor(
+  new Date("2100-01-01T00:00:00.000Z").getTime() / 1000,
+);
+
+const createJwtPayload = (overrides: Partial<JwtPayload> = {}): JwtPayload => {
+  return {
+    ...createTodoJwtPayload("1234", "admin", "admin", fixedPayloadDate),
+    exp: fixedExpInSeconds,
+    iat: fixedIatInSeconds,
+    ...overrides,
+  };
+};
+
 describe("pageJwtMiddleware", () => {
   test("redirects to login when JWT cookie is missing", async () => {
     const appConfig = createAppConfig({
@@ -48,7 +68,7 @@ describe("pageJwtMiddleware", () => {
     const appConfig = createAppConfig({
       JWT_SECRET: "12345678901234567890123456789012",
     });
-    const token = await sign({ sub: "1234" }, appConfig.jwt.secret, "HS256");
+    const token = await sign(createJwtPayload(), appConfig.jwt.secret, "HS256");
     let handlerReached = false;
     const app = new Hono<{ Variables: AppVariables }>()
       .use("*", createAppConfigMiddleware(appConfig))
@@ -74,7 +94,7 @@ describe("pageJwtMiddleware", () => {
     const appConfig = createAppConfig({
       JWT_SECRET: "12345678901234567890123456789012",
     });
-    const token = await sign({ sub: "1234" }, appConfig.jwt.secret, "HS256");
+    const token = await sign(createJwtPayload(), appConfig.jwt.secret, "HS256");
     const app = new Hono<{ Variables: AppVariables }>()
       .use("*", createAppConfigMiddleware(appConfig))
       .use("*", pageJwtMiddleware)
@@ -93,3 +113,42 @@ describe("pageJwtMiddleware", () => {
     expect(response.status).toBe(500);
   });
 });
+
+describe("createTodoJwtPayload", () => {
+  test("maps user fields and static issuer", () => {
+    const now = new Date("2026-05-24T12:00:00.000Z");
+
+    const payload = createTodoJwtPayload("user-123", "admin", "editor", now);
+
+    expect(payload.sub).toBe("user-123");
+    expect(payload.preferred_username).toBe("admin");
+    expect(payload.role).toBe("editor");
+    expect(payload.iss).toBe("todo-app");
+  });
+
+  test("sets iat to current time in seconds", () => {
+    const now = new Date("2026-05-24T12:34:56.000Z");
+
+    const payload = createTodoJwtPayload("user-1", "user", "admin", now);
+
+    expect(payload.iat).toBe(Math.floor(now.getTime() / 1000));
+  });
+
+  test("sets exp to one day after current time in seconds", () => {
+    const now = new Date("2026-05-24T12:34:56.000Z");
+
+    const payload = createTodoJwtPayload("user-1", "user", "admin", now);
+
+    expect(payload.exp).toBe(Math.floor(addDays(now, 1).getTime() / 1000));
+    expect(payload.exp - payload.iat).toBe(24 * 60 * 60);
+  });
+
+  test("floors fractional milliseconds for both iat and exp", () => {
+    const now = new Date("2026-05-24T12:34:56.789Z");
+
+    const payload = createTodoJwtPayload("user-1", "user", "admin", now);
+
+    expect(payload.iat).toBe(Math.floor(now.getTime() / 1000));
+    expect(payload.exp).toBe(Math.floor(addDays(now, 1).getTime() / 1000));
+  });
+});

src/shared/pageJwtMiddleware.ts

@@ -1,8 +1,38 @@
+import { addDays } from "date-fns";
 import { createMiddleware } from "hono/factory";
 import { jwt } from "hono/jwt";
+import z from "zod";
 import type { AppVariables } from "./appVariables.ts";
 import { pageRoutes } from "./pageRoutes.ts";
 
+const jwtPayloadSchema = z.object({
+  sub: z.string(),
+  preferred_username: z.string(),
+  role: z.string(),
+  iss: z.string(),
+  exp: z.number(),
+  iat: z.number(),
+});
+
+export type JwtPayload = z.infer<typeof jwtPayloadSchema>;
+
+export function createTodoJwtPayload(
+  userId: string,
+  username: string,
+  role: string,
+  now: Date,
+): JwtPayload {
+  const iat: number = Math.floor(now.getTime() / 1000);
+  return {
+    sub: userId,
+    preferred_username: username,
+    role,
+    iss: "todo-app",
+    exp: Math.floor(addDays(now, 1).getTime() / 1000),
+    iat,
+  };
+}
+
 export const pageJwtMiddleware = createMiddleware<{ Variables: AppVariables }>(
   async (c, next) => {
     const appConfig = c.var.appConfig;
@@ -14,6 +44,8 @@ export const pageJwtMiddleware = createMiddleware<{ Variables: AppVariables }>(
 
     try {
       await verifyJwt(c, async () => {});
+      const jwtPayload = jwtPayloadSchema.parse(c.var.jwtPayload);
+      c.set("validJwtPayload", jwtPayload);
     } catch {
       return c.redirect(pageRoutes.LOGIN);
     }