OpenAI Symphony 🗂, laws of software engineering ⚖️, GitHub Copilot pricing change 💵

Symphony is an open-source specification for an agent orchestrator designed to address the bottleneck of human engineers micromanaging coding agents ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌  ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ 

Sign Up |Advertise|View Online TLDR Together With  TLDR Dev 2026-04-28 Get The Right Kind of Attention From Developers. (Sponsor) You've built an amazing developer tool. Now you just need to get people excited about it. What kind of content performs best? Should you sponsor creators? Which ones? How do you measure influencer ROI? Freeman & Forrest can help. Founded by developers, they build ethical, high-performing influencer marketing programs for some of the best-known companies in tech. See how Postman built a sustainable influencer program Book a free consultation with F&F today! 🧑‍💻 Articles & Tutorials 3 ways to store variables in React, and why you shouldn't sleep on useRef (4 minute read) There are three ways to store variables in React, with a particular focus on the `useRef` hook. Vanilla JavaScript variables are temporary and do not cause UI updates, while `useState` variables persist, update the UI, and are essential for reactive components.`useRef` allows data to persist and be mutable across renders without triggering a re-render of the UI. Selective Test Execution at Stripe: Fast CI for a 50M-line Ruby monorepo (8 minute read) Stripe manages a 50M-line Ruby monorepo by using a C++ library to track file access during tests, allowing them to run only 5% of the test suite per build. This selective execution process is made reproducible by using Monotonic Revision IDs to fetch test baselines from MongoDB without needing to traverse git history. 🧠 Opinions & Advice The unwritten laws of software engineering (8 minute read) Experienced software engineers often learn critical "unwritten rules" through trial and error, such as the importance of rollback plans, rigorous backup testing, and the "four eyes" rule for risky changes. This article outlines seven essential principles that help developers create more reliable systems by avoiding operational pitfalls and temporary fixes. Meetings are forcing functions (2 minute read) Regular, standing meetings serve as effective forcing functions for complex, long-running projects by creating accountability and ensuring dedicated time for progress. 3 constraints before I build anything (4 minute read) For creativity when building, every idea must meet three constraints. These constraints require distilling the idea into a clarity-driven "one-pager," making sure the core technology is independently viable for leverage, and defining the product by a single, guiding constraint to prevent feature bloat. 🚀 Launches & Tools The search engine behind Cursor's agents (Sponsor) turbopuffer is the search engine that Cursor uses to connect agents to every codebase. It's built on object storage, with smart caching on NVMe SSDs, so it's 10x cheaper than traditional RAG databases but just as fast (p90 < 20ms). Read how Cursor cut costs 20x and improved agent reasoning An open-source spec for Codex orchestration: Symphony (55 minute read) Symphony is an open-source specification for an agent orchestrator designed to address the bottleneck of human engineers micromanaging coding agents. It transforms project management boards like Linear into control planes, continuously assigning tasks to agents in dedicated workspaces and handling their execution. The system boosts productivity, with some teams seeing a 500% increase in landed pull requests, by allowing humans to focus on higher-level, ambiguous problems rather than supervising agents. Sup (Website) Sup is a terminal-based email client designed for managing large volumes of mail through tagging and hierarchical threading. It has powerful local search and a Ruby hook system, making it an efficient tool for users who treat their inbox as a searchable archive. Dirac (GitHub Repo) Dirac is an open-source AI coding agent designed for high accuracy and token efficiency. Available as a VS Code extension and CLI, it provides a powerful, cost-effective solution that reduces API costs by an average of 64.8% through methods like optimized context curation, AST manipulation, and autonomous tool use. 🎁 Miscellaneous The woes of sanitizing SVGs (15 minute read) Scratch's reliance on complex, manual sanitization for directly embedded user-generated SVGs has proven unsustainable, repeatedly failing to prevent vulnerabilities like XSS and HTTP leaks. There are other alternatives that successfully sandbox SVGs within an `iframe` using a strict Content Security Policy. Two years without cookies on the site, here's where we ended up (9 minute read) Sentry's removal of advertising cookies and tracking two years ago forced a shift toward awareness-based growth, with 70% of its budget now targeting channels like sponsorships and podcasts. This transition from pixel tracking to holistic data analysis and authentic engagement has unexpectedly driven exponential growth in new activated users. ⚡ Quick Links Try the AI observability and evals platform trusted by OpenAI, Notion, and Ramp (Sponsor) Every AI team has shipped a change that unexpectedly broke prod. Braintrust is how leaders including OpenAI, Lovable, and Vercel catch regressions before users do. Sign up free now GitHub Copilot is moving to usage-based billing (7 minute read) On June 1, GitHub Copilot will transition to usage-based billing, where all plans will consume AI Credits based on token usage instead of premium requests to align pricing with actual usage. Is Your Site Agent-Ready? (Website) This is a service to scan websites and determine their readiness for AI agents by checking against multiple emerging standards. Collective Speed Is Not the Summation of Individual Speed (2 minute read) A company's collective speed, much like a relay race, depends more on the effective interfaces and relationships between its people than on the individual speed of its coders. Welcome to the “find out” stage of AI (12 minute read) As AI enters its "find out" stage, the industry is shifting from experimentation to delivering reliable real-world value for businesses. Love TLDR? Tell your friends and get rewards! Share your referral link below with friends to get free TLDR swag! https://refer.tldr.tech/d0af4569/3 Track your referrals here. Want to advertise in TLDR? 📰 If your company is interested in reaching an audience of web developers and engineering decision makers, you may want to advertise with us. Want to work at TLDR? 💼 Apply here, create your own role or send a friend's resume to jobs@tldr.tech and get $1k if we hire them! TLDR is one of Inc.'s Best Bootstrapped businesses of 2025. If you have any comments or feedback, just respond to this email! Thanks for reading, Priyam Mohanty, Jenny Xu & Ceora Ford Manage your subscriptions to our other newsletters on tech, startups, and programming. Or if TLDR Dev isn't for you, please unsubscribe.