Add formatted error pages for console and browser

Errors now show app frames highlighted with relative paths and library
frames collapsed, both in ANSI on the console and as a styled HTML page
in the browser. Process-level uncaughtException/unhandledRejection
handlers also use the formatter.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app.ts

@@ -1,171 +1,30 @@
-import express, {
-    type Request as ExpressRequest,
-    type Response as ExpressResponse,
-} from "express";
-import { match } from "path-to-regexp";
-import { Session } from "./diachron/auth";
-import { cli } from "./diachron/cli";
-import { contentTypes } from "./diachron/content-types";
-import { runWithContext } from "./diachron/context";
+import{cli}from'./diachron/cli'
+import { formatError } from './diachron/errors';
+
+process.on('uncaughtException', (err) => {
+    console.error(formatError(err));
+    process.exit(1);
+});
+
+process.on('unhandledRejection', (reason) => {
+    console.error(formatError(reason));
+});
+
 import { core } from "./diachron/core";
-import { httpCodes } from "./diachron/http-codes";
-import { request } from "./diachron/request";
-// import { URLPattern } from 'node:url';
-import {
-    AuthenticationRequired,
-    AuthorizationDenied,
-    type Call,
-    type InternalHandler,
-    isRedirect,
-    type Method,
-    massageMethod,
-    methodParser,
-    type ProcessedRoute,
-    type Result,
-    type Route,
-} from "./diachron/types";
+
 import { routes } from "./routes";
+import {makeApp}from'./diachron/app'
 
-const app = express();
 
-// Parse request bodies
-app.use(express.json());
-app.use(express.urlencoded({ extended: true }));
+const app = makeApp({routes});
+
 
 core.logging.log({ source: "logging", text: ["1"] });
-const processedRoutes: { [K in Method]: ProcessedRoute[] } = {
-    GET: [],
-    POST: [],
-    PUT: [],
-    PATCH: [],
-    DELETE: [],
-};
 
-function _isPromise<T>(value: T | Promise<T>): value is Promise<T> {
-    return typeof (value as any)?.then === "function";
-}
 
-routes.forEach((route: Route, _idx: number, _allRoutes: Route[]) => {
-    // const pattern /*: URLPattern */ = new URLPattern({ pathname: route.path });
-    const matcher = match<Record<string, string>>(route.path);
-    const methodList = route.methods;
 
-    const handler: InternalHandler = async (
-        expressRequest: ExpressRequest,
-    ): Promise<Result> => {
-        const method = massageMethod(expressRequest.method);
 
-        console.log("method", method);
 
-        if (!methodList.includes(method)) {
-            // XXX: Worth asserting this?
-        }
-
-        console.log("request.originalUrl", expressRequest.originalUrl);
-
-        // Authenticate the request
-        const auth = await request.auth.validateRequest(expressRequest);
-
-        const req: Call = {
-            pattern: route.path,
-            path: expressRequest.originalUrl,
-            method,
-            parameters: { one: 1, two: 2 },
-            request: expressRequest,
-            user: auth.user,
-            session: new Session(auth.session, auth.user),
-        };
-
-        try {
-            const retval = await runWithContext({ user: auth.user }, () =>
-                route.handler(req),
-            );
-            return retval;
-        } catch (error) {
-            // Handle authentication errors
-            if (error instanceof AuthenticationRequired) {
-                return {
-                    code: httpCodes.clientErrors.Unauthorized,
-                    contentType: contentTypes.application.json,
-                    result: JSON.stringify({
-                        error: "Authentication required",
-                    }),
-                };
-            }
-            if (error instanceof AuthorizationDenied) {
-                return {
-                    code: httpCodes.clientErrors.Forbidden,
-                    contentType: contentTypes.application.json,
-                    result: JSON.stringify({ error: "Access denied" }),
-                };
-            }
-            throw error;
-        }
-    };
-
-    for (const [_idx, method] of methodList.entries()) {
-        const pr: ProcessedRoute = { matcher, method, handler };
-
-        processedRoutes[method].push(pr);
-    }
-});
-
-async function handler(
-    req: ExpressRequest,
-    _res: ExpressResponse,
-): Promise<Result> {
-    const method = await methodParser.parseAsync(req.method);
-
-    const byMethod = processedRoutes[method];
-    console.log(
-        "DEBUG: req.path =",
-        JSON.stringify(req.path),
-        "method =",
-        method,
-    );
-    for (const [_idx, pr] of byMethod.entries()) {
-        const match = pr.matcher(req.path);
-        console.log("DEBUG: trying pattern, match result =", match);
-        if (match) {
-            console.log("match", match);
-            const resp = await pr.handler(req);
-
-            return resp;
-        }
-    }
-
-    const retval: Result = {
-        code: httpCodes.clientErrors.NotFound,
-        contentType: contentTypes.text.plain,
-        result: "not found!",
-    };
-
-    return retval;
-}
-
-app.use(async (req: ExpressRequest, res: ExpressResponse) => {
-    const result0 = await handler(req, res);
-
-    const code = result0.code.code;
-    const result = result0.result;
-
-    console.log(result);
-
-    // Set any cookies from the result
-    if (result0.cookies) {
-        for (const cookie of result0.cookies) {
-            res.cookie(cookie.name, cookie.value, cookie.options ?? {});
-        }
-    }
-
-    if (isRedirect(result0)) {
-        res.redirect(code, result0.redirect);
-    } else {
-        res.status(code).send(result);
-    }
-});
-
-process.title = `diachron:${cli.listen.port}`;
 
 app.listen(cli.listen.port, cli.listen.host, () => {
     console.log(`Listening on ${cli.listen.host}:${cli.listen.port}`);