The latest articles on Forem by Andreas Bergström (@andreasbergstrom). https://forem.com/andreasbergstrom https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F153469%2F5c1970f5-0d22-46e9-af0c-6931bb91d856.jpg https://forem.com/andreasbergstrom en Andreas Bergström Sun, 10 Aug 2025 10:32:13 +0000 https://forem.com/andreasbergstrom/using-fastmcp-with-openai-and-avoiding-session-termination-issues-k3h https://forem.com/andreasbergstrom/using-fastmcp-with-openai-and-avoiding-session-termination-issues-k3h <p>If you're plugging a FastMCP server into OpenAI's Responses API and your sessions keep dying with <code>Session has been terminated</code>, the fix is one flag: <code>stateless_http=True</code> when you instantiate <code>FastMCP(...)</code>. OpenAI sends a <code>DELETE</code> after each call without recreating the session, so anything stateful gets terminated between requests.</p> <p>The full post covers the JSON-RPC error you'll actually see, the minimal server change to make it work, and the caveats — session state and certain bi-directional streaming patterns drop out in stateless mode. Worth a quick read if you're hitting the same one-call-then-broken behaviour.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/fastmcp-openai-session-termination" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> ai fastmcp openai mcp Andreas Bergström Mon, 27 Nov 2023 19:53:11 +0000 https://forem.com/andreasbergstrom/redirecting-mobile-users-to-app-or-play-store-using-nextjs-3pp1 https://forem.com/andreasbergstrom/redirecting-mobile-users-to-app-or-play-store-using-nextjs-3pp1 <p>If you're promoting a mobile app for both iOS and Android and want a single URL or QR code that drops users into the correct store, you don't need a 3rd-party redirect service. A NextJS middleware that matches <code>userAgent</code> against <code>iP(hone|ad|od)</code> and <code>Android</code> regexes does it in ~15 lines, runs before any render, and keeps the contact point — and any SEO it earns — on your own domain.</p> <p>The full post walks through the <code>middleware.ts</code> plus the placeholder <code>app/get.tsx</code> page that triggers it, with notes on the iOS-vs-Android UX quirk and why owning that redirect matters once QR codes are out in the wild and outlive your vendor relationships.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/nextjs-mobile-app-store-redirect" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> nextjs mobile javascript typescript Andreas Bergström Sat, 11 Nov 2023 16:37:38 +0000 https://forem.com/andreasbergstrom/python-del-vs-assigning-to-none-5387 https://forem.com/andreasbergstrom/python-del-vs-assigning-to-none-5387 <p>Both <code>x = None</code> and <code>del x</code> look like ways to release a variable in Python, but they aren't equivalent. <code>x = None</code> keeps the name bound and just rebinds it to <code>NoneType</code> (still ~16 bytes); <code>del x</code> removes the binding entirely so the name itself is gone. Touch <code>x</code> after <code>del</code> and you get a <code>NameError</code>.</p> <p>The full post walks through a worked example with <code>sys.getsizeof</code> and <code>gc.collect()</code> showing the byte difference, then disassembles both versions with <code>dis.dis</code> so you can see <code>del</code> compiles to a single <code>DELETE_FAST</code> while assigning to <code>None</code> becomes a <code>LOAD_CONST</code> + <code>STORE_FAST</code> pair.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/python-del-vs-none" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> python performance Andreas Bergström Mon, 16 Oct 2023 18:19:32 +0000 https://forem.com/andreasbergstrom/node-21-might-have-websockets-built-in-24f3 https://forem.com/andreasbergstrom/node-21-might-have-websockets-built-in-24f3 <p>Node 21 finally ships with a built-in WebSocket client — no more pulling in <code>ws</code> or <code>socket.io-client</code> for a basic browser-style API on the server side. Deno and Bun have shipped this for a while; this closes the gap.</p> <p>The full post (written just ahead of the v21 release) tracks the upstream Undici PR and the long-running Node issue thread that pushed it across the finish line, with a link to the v21 release announcement once it landed.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/node-21-built-in-websocket" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> node Andreas Bergström Sun, 15 Oct 2023 08:39:24 +0000 https://forem.com/andreasbergstrom/configure-typeorm-migrations-in-5-minutes-2njg https://forem.com/andreasbergstrom/configure-typeorm-migrations-in-5-minutes-2njg <p>Setting up TypeORM migrations in a NestJS project is fiddly across two configs and four npm scripts the first time you do it, but mechanical once you know the shape. Wire <code>migrationsRun: true</code> into <code>TypeOrmModule.forRootAsync</code>, add a separate <code>typeorm.config.ts</code> <code>DataSource</code> for the CLI to import, and four package.json scripts cover run/generate/create/revert.</p> <p>The full post has the exact <code>app.module.ts</code>, <code>typeorm.config.ts</code>, and <code>package.json</code> snippets to copy, plus notes on why <code>synchronize</code> should never be true in production and how <code>generate-migration</code> diffs your entities against the live schema to write the SQL for you.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/typeorm-migrations-nestjs" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> nestjs typeorm javascript typescript Andreas Bergström Sat, 14 Oct 2023 07:45:23 +0000 https://forem.com/andreasbergstrom/easily-style-active-links-in-tanstack-router-7n https://forem.com/andreasbergstrom/easily-style-active-links-in-tanstack-router-7n <p>TanStack Router's <code>Link</code> accepts an <code>activeProps</code> prop that gets spread onto the rendered element only when the link matches the current route — including <code>className</code>. So styling the active item in a navbar is just <code>&lt;Link activeProps={{ className: 'text-black' }}&gt;</code> — no <code>useMatches</code>, no manual <code>pathname</code> comparison.</p> <p>The full post has a short <code>MainNav</code> example mapping menu items to <code>Link</code>s plus a pointer to TanStack's docs for the rest of the active-state knobs.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/tanstack-router-active-link-styles" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> javascript react webdev ux Andreas Bergström Sat, 09 Sep 2023 07:33:31 +0000 https://forem.com/andreasbergstrom/finally-you-can-skip-dotenv-in-node-14ml https://forem.com/andreasbergstrom/finally-you-can-skip-dotenv-in-node-14ml <p>Node 20.6 added built-in <code>.env</code> file loading, so <code>node --env-file=.env index.js</code> does what <code>dotenv</code> used to. It also picks up <code>NODE_OPTIONS</code> from the same file — convenient when you want flags like <code>--experimental-modules</code> colocated with the rest of your runtime config rather than scattered between <code>package.json</code> and shell.</p> <p>The full post covers the syntax, why this still doesn't help React or React Native (those don't run on the Node runtime in prod), and where Vite/Astro projects already had a similar story for their own dev servers.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/node-built-in-env-file-no-dotenv" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> node javascript npm Andreas Bergström Sun, 13 Aug 2023 18:21:07 +0000 https://forem.com/andreasbergstrom/how-to-easily-use-media-queries-for-print-in-tailwind-2o9a https://forem.com/andreasbergstrom/how-to-easily-use-media-queries-for-print-in-tailwind-2o9a <p>Tailwind doesn't expose <code>print:</code> and <code>screen:</code> modifiers by default, but extending <code>theme.screens</code> in <code>tailwind.config.js</code> with <code>print: { raw: 'print' }</code> and <code>screen: { raw: 'screen' }</code> opens them up — no plugin needed. Then <code>print:hidden</code> on the navbar, <code>print:text-xl</code> for paper-friendly typography, and <code>print:block</code> toggles for swapping to a grayscale image just work.</p> <p>The full post covers the config tweak, the handful of classes that matter most for print (hide chrome, swap images, surface link URLs via a tiny CSS rule), and why it's worth caring at all for document-oriented sites.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/tailwind-print-styles" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> tailwindcss webdev css Andreas Bergström Thu, 10 Aug 2023 07:49:17 +0000 https://forem.com/andreasbergstrom/understanding-cache-control-and-etag-for-efficient-web-caching-2nf5 https://forem.com/andreasbergstrom/understanding-cache-control-and-etag-for-efficient-web-caching-2nf5 <p><code>Cache-Control</code> and <code>ETag</code> solve different halves of the same problem and are at their best together: <code>Cache-Control</code> says how long the client can skip the server entirely (<code>max-age</code>, <code>no-cache</code>, <code>public</code>/<code>private</code>, <code>must-revalidate</code>); <code>ETag</code> is the freshness check used when the cache does want to ask — the client sends <code>If-None-Match</code>, the server replies <code>304 Not Modified</code> if the tag matches and saves the bytes.</p> <p>The full post walks through the directives, what <code>If-None-Match</code> looks like on the wire, and why <code>ETag</code>-only is worse than the pair (more round trips, no public/private split, no <code>immutable</code> on versioned assets).</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/http-cache-control-etag" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> http webdev webperf caching Andreas Bergström Wed, 09 Aug 2023 07:49:22 +0000 https://forem.com/andreasbergstrom/simplify-typescript-builds-with-esbuild-and-skip-tsctsx-2124 https://forem.com/andreasbergstrom/simplify-typescript-builds-with-esbuild-and-skip-tsctsx-2124 <p>If <code>tsc</code> (or <code>tsx</code> in dev) is the slow step in your TypeScript build, esbuild can replace both. A single npm script — <code>esbuild $(find src -name '*.ts') --platform=node --target=esnext --outdir=build --format=cjs</code> — does the same job in a fraction of the time, and <code>--watch</code> makes it usable as the dev compiler too.</p> <p>The full post breaks down each esbuild flag (<code>--platform</code>, <code>--target</code>, <code>--format</code>, <code>--outdir</code>, <code>--watch</code>), shows the <code>package.json</code> scripts for build/dev/watch, and pairs it with <code>concurrently</code> for a single dev-server command.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/esbuild-typescript-skip-tsc" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> node typescript javascript webdev Andreas Bergström Tue, 08 Aug 2023 05:51:17 +0000 https://forem.com/andreasbergstrom/packagejson-not-just-a-file-but-a-developers-toolkit-2666 https://forem.com/andreasbergstrom/packagejson-not-just-a-file-but-a-developers-toolkit-2666 <p><code>package.json</code> is more than a manifest — npm <code>scripts</code> is a small task runner with hooks, env-var injection, lifecycle stages, and parallel execution baked in. <code>pre</code>/<code>post</code> prefixes auto-bracket a task with setup/teardown; <code>process.env.npm_package_*</code> lets scripts read their own metadata; <code>concurrently npm:start:*</code> fans out a handful of related scripts in one command.</p> <p>The full post collects the patterns worth knowing — pre/post hooks, env vars, <code>cross-env</code>, <code>concurrently</code>/<code>npm-run-all</code>, lifecycle scripts like <code>prepublish</code>, command-line argument forwarding via <code>--</code>, and when <code>&amp;&amp;</code>/<code>&amp;</code> is fine vs when you actually want a task runner.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/package-json-npm-scripts-toolkit" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> node npm Andreas Bergström Mon, 07 Aug 2023 12:28:22 +0000 https://forem.com/andreasbergstrom/the-future-of-ai-assistants-revolutionizing-app-settings-using-large-language-models-382e https://forem.com/andreasbergstrom/the-future-of-ai-assistants-revolutionizing-app-settings-using-large-language-models-382e <p>App settings menus have grown into the Yellow Pages of software — a maze of toggles and sliders nobody actually wants to navigate. LLM-backed assistants suggest a way out: instead of digging for the dark-mode toggle, you tell the assistant "dark theme, no notifications during work, max privacy" and it walks the settings on your behalf.</p> <p>The full post argues this is the next CLI-to-GUI-style shift — settings as conversation rather than form — and what app developers and AI researchers need to get right (privacy, bias, reliability) for that transition not to fall on its face.</p> <p><em>Originally published at <a href="https://andreasbergstrom.dev/posts/ai-assistants-app-settings" rel="noopener noreferrer">andreasbergstrom.dev</a> — read the full post there.</em></p> llm ai machinelearning chatgpt