---
title: "Latest reads"
description: "The engineering internet, summarised so you can actually read it."
---

# Latest reads
> The engineering internet, summarised so you can actually read it.

## Articles

### [Building Effective AI Agents](https://yomu.fyi/post/building-effective-ai-agents.md)
- Company: [Anthropic](https://yomu.fyi/company/anthropic.md)
- Published: Dec 19, 2024
- Type: Explainer

Effective agentic systems need not begin with complex frameworks: the post reports that successful implementations commonly use simple, composable patterns and recommends choosing the least complex solution that meets the task's needs. It distinguishes workflows, which follow predefined code paths, from agents, where LLMs dynamically direct their processes and tool use. The proposed foundation is an augmented LLM with retrieval, tools, and memory, potentially integrated through the Model Context Protocol; larger designs include prompt chaining, routing, parallelization, and orchestrator-workers patterns. Frameworks can simplify implementation but may obscure prompts and responses, so direct API use and understanding underlying code are recommended. Tool definitions are treated as an interface requiring testing, clear examples, low formatting overhead, and mistake-resistant parameters; absolute filepaths eliminated observed errors in a coding agent.


### [Crush errors with Sandbox testing](https://yomu.fyi/post/crush-errors-with-sandbox-testing.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: David Edoh-Bedi
- Published: Dec 19, 2024
- Type: Tutorial

Payment integrations can encounter errors caused by external events, such as network issues or outages, or by bugs in application code, and unhandled failures can stall checkout. The post presents Stripe Sandboxes as isolated environments for reproducing live-integration failures without changing live payment settings or traffic, optionally copying settings when a sandbox is created. Developers can use Workbench’s Errors and Logs views to diagnose a card\_declined response, then route test requests through sandbox keys and a test card. On the Python backend, a try/except implementation catches Stripe errors and generic exceptions and returns an error response instead of leaving the payment page stalled. Sandboxes remain separate after creation, but each Stripe account can have at most five, so unused environments may be deleted or have their test data cleared while settings are preserved.


### [Testing Connect onboarding with Sandboxes](https://yomu.fyi/post/testing-connect-onboarding-with-sandboxes.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: David Edoh-Bedi
- Published: Dec 19, 2024
- Type: Tutorial

Stripe Connect testing can become unwieldy as platforms cover payment methods, US states, international countries, and merchant verification conditions, while the existing test mode stays synchronized with live settings. Sandboxes provide an isolated environment that can replicate a platform’s live configuration without affecting live payment traffic. The workflow covers creating a Sandbox, confirming that Connect settings such as negative-liability handling were preserved, and onboarding test connected accounts through Stripe-provided or custom flows. To reproduce a website-verification failure, a custom account can use “https://inaccessible.stripe.com”; after testing an update to “https://accessible.stripe.com” in the Sandbox, the platform can apply the fix to its production onboarding flow.


### [Heroku CLI v10: Support for Next Generation Heroku Platform](https://yomu.fyi/post/heroku-cli-v10-support-for-next-generation-heroku-platform.md)
- Company: [Heroku](https://yomu.fyi/company/heroku.md)
- Author: Anush DSouza
- Published: Dec 17, 2024
- Type: Announcement

Heroku CLI v10.0.0 updates the command-line tool for the next-generation Fir platform while introducing breaking changes and a Node.js 20 runtime. Fir users must replace several legacy command forms, including logs and ps:stop/ps:restart arguments, and use heroku run:inside because heroku run, ps:exec, ps:copy, ps:forward, and ps:socks do not work with Fir apps. New Fir support includes heroku telemetry commands for OpenTelemetry, a generation selector for spaces:create, generation details in space commands, Fir-aware pipeline and buildpack output, and real-time log streaming with --tail. The release also upgrades oclif to v4.14.36, updates GitHub workflows to Node 20, fixes log color rendering, and is available through heroku update.


### [Developing a modern architecture for energy utilities with embedded finance](https://yomu.fyi/post/developing-a-modern-architecture-for-energy-utilities-with-embedded-fi.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: Rajan Patel
- Published: Dec 17, 2024
- Type: Explainer

Energy utilities can use embedded finance to create marketplace-like experiences for tariffs, solar installations, smart-home devices, storage, and related services while capturing more energy-related revenue. The proposed foundation combines Stripe Online Payment Flows, Billing, Payments, Connect, and Data Pipeline with AWS serverless services, including Lambda, EventBridge, DynamoDB, Redshift, S3, and QuickSight. A tariff enrollment or payment can trigger webhooks and real-time event processing, while transaction and customer data support dashboards, usage insights, personalized recommendations, subscriptions, and broader partner offerings. The architecture also describes PCI Level 1 security, encryption, Radar, Strong Customer Authentication, AWS IAM, KMS, Shield, WAF, Config, Security Hub, and CloudWatch for compliance and monitoring. It concludes that this integrated payment, analytics, and security foundation can help utilities improve customer engagement, support sustainable programs, and develop new revenue streams.


### [How do I store inventory data in my Stripe application](https://yomu.fyi/post/how-do-i-store-inventory-data-in-my-stripe-application.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: Ben Smith
- Published: Dec 16, 2024
- Type: Tutorial

The DevRel Swag Store uses Stripe payments and AWS services to keep product inventory accurate and visible in near real time. Stripe products retain core payment information, while Amazon DynamoDB stores inventory and other attributes, keyed by Stripe product ID and store ID; EventBridge routes payment events to Lambda, which atomically decrements stock and publishes updates through AWS IoT Core to the frontend. DynamoDB condition expressions prevent decrements when stock is insufficient, while post-payment validation and refunds address the delay before a Stripe Payment Link is disabled, although Stripe fees may be non-refundable. A custom Payment Intent flow can check stock before payment, authorize funds with manual capture for up to seven days, update inventory after payment success, and then capture the charge.


### [Japan community highlights: Effective testing and security](https://yomu.fyi/post/japan-community-highlights-effective-testing-and-security.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: Hidetaka Okamoto
- Published: Dec 13, 2024
- Type: Explainer

This article reports practical lessons from two September 2024 JP\_Stripes events in Aizuwakamatsu and Sapporo for developing and operating Stripe-integrated services more efficiently and at lower cost. Sandboxes let teams create up to five separate test environments, reproduce payment failures and state transitions through Stripe's API, and use CI-specific workspaces without production access. Stripe Connect examples show how a three-person codoc team launched in nine months by staggering account creation and embedding payout and payment-management interfaces. For fraud prevention, the article recommends Radar or Radar for Teams with webhook automation, including early-fraud-warning events and preemptive cancellation or refunds when dispute fees exceed transaction value. Together, these cases emphasize using managed Stripe capabilities and community-shared implementation experience to reduce testing effort, UI work, and fraud-related costs.


### [Turbocharging GrabUnlimited with Temporal](https://yomu.fyi/post/turbocharging-grabunlimited-with-temporal.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Michel Parreno
- Published: Dec 12, 2024
- Type: Problem & solution

Grab’s GrabUnlimited flagship membership program struggled as subscribers grew by over 1000% from January 2022 to June 2023. Its original design used a daily cron job for renewals, Amazon’s SQS to distribute state handlers, and five-minute Redis locks, but outages, corrupted states, concurrent cancellation and renewal, missed benefits, and non-idempotent retries created operational problems. The team migrated the service to a Temporal workflow-based system, enhancing its ability to handle millions of subscribers with greater efficiency and resilience. The source reports an 80% reduction in open production incidents and says the change improved the membership experience for users. This first part focuses on designing a robust and scalable membership system, while migration challenges and lessons are reserved for a subsequent installment.


### [The science of routing print orders](https://yomu.fyi/post/the-science-of-routing-print-orders.md)
- Company: [Canva](https://yomu.fyi/company/canva.md)
- Author: Constantinos Kavadias
- Published: Dec 10, 2024
- Type: Problem & solution

Canva's global print network requires selecting optimal suppliers to balance delivery times, packaging counts, and environmental emissions. To resolve these challenges before user checkout, the engineering team designed a modular routing architecture that decouples graph construction, decision logic, and path traversal. During graph traversal, the system generates action objects capturing forward paths and decision query results, which are compiled into timestamped routing logs in blob storage for asynchronous auditing. Utilizing preprocessed graph queries alongside ElastiCache, Redis, and database read replicas, the infrastructure sustains high-throughput evaluation without coupling cost logic to traversal code. As a result, print routing completes within an average of 50 milliseconds at the 99th percentile during peak usage while maintaining 99.999% data availability.


### [Enhance your monitoring by integrating Stripe events with AWS CloudWatch Log Groups](https://yomu.fyi/post/enhance-your-monitoring-by-integrating-stripe-events-with-aws-cloudwat.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: Andrew Robinson
- Published: Dec 9, 2024
- Type: Tutorial

Stripe events notify account owners about changes such as successful charges, failed invoice payments, and available reconciliation reports. Because Stripe retains events for 13 months but exposes older events than 30 days only as summaries, Amazon EventBridge can route them into an AWS account and Amazon CloudWatch Log Groups can provide longer-term monitoring and analysis. The setup uses CloudWatch metric filters to match event types such as invoice.payment\_failed, convert matches into custom metrics, and support alarms, Amazon SNS notifications, dashboards, and Logs Insights queries. For example, a failed-invoice alarm can use a five-minute observation period, Sum statistics, and a threshold based on expected failure volume or anomaly detection. The resulting setup supports near-real-time visibility into successful charges and failed payments, historical trend analysis, troubleshooting, and responses to unusual activity.


### [How we seamlessly migrated high volume real-time streaming traffic from one service to another with zero data loss and duplication](https://yomu.fyi/post/how-we-seamlessly-migrated-high-volume-real-time-streaming-traffic-fro.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Md Riyadh
- Published: Dec 5, 2024
- Type: Problem & solution

Grab migrated its stream-processing (write) functionality from an existing service into a separate service while handling 20,000 reads per second from 16 Kafka streams and writing to output streams and DynamoDB tables. The migration required gradual stream-by-stream rollout, production validation, and a no-downtime switchover; feature flags were rejected because deployment timing could cause loss, duplication, or inconsistent values. The team moved processing into shared /commons code, created temporary validation sinks, and scheduled each switchover with a shared map\[string\]time.Time, allowing both services to change writers at the same time. During each cutover, both services consumed streams, the old service stopped writing to resources, and monitoring continued before old consumption was removed; the result was zero data loss or duplication, no downtime, and completion in about three weeks. It was temporary and tested, but rolling back either service could create inconsistency if systems fell out of sync.


### [Friday, 4 PM: Best Time to Post on YouTube](https://yomu.fyi/post/friday-4-pm-best-time-to-post-on-youtube.md)
- Company: [Brandwatch](https://yomu.fyi/company/brandwatch.md)
- Author: Mélanie Corolleur
- Published: Dec 2, 2024
- Type: Tutorial

The guide examines whether publishing time affects YouTube performance, while arguing that content quality, channel consistency, and audience preferences matter more than any universal schedule. It explains that early views, comments, and shares provide feedback to YouTube’s recommendation system, which can then surface videos to followers and other viewers on the home page and in suggested videos. General patterns favor afternoons and evenings, with Friday at about 4 p.m. identified as the strongest broad slot, although day-by-day windows vary and evergreen tutorials may benefit more from search-oriented titles and descriptions. The recommended workflow uses YouTube Studio Analytics and the “When your viewers are on YouTube” heatmap to select candidate times, then checks later engagement to see whether those patterns hold.


### [Supercharging LLM application development with LLM-Kit](https://yomu.fyi/post/supercharging-llm-application-development-with-llm-kit.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Boon Zhan Chew
- Published: Nov 29, 2024
- Type: Problem & solution

Grab developed LLM-Kit, a comprehensive framework for setting up production-ready Generative AI applications while addressing security, scalability, integration, monitoring, and standardisation concerns. Its pre-configured structure includes an API server, configuration management, a sample LLM Agent, tests, and an integrated stack spanning Poetry, Gunicorn, FastAPI, LangChain, LangSmith, HashiCorp Vault, Amazon EKS, and GitLab CI. Engineers submit application details through a form, which triggers GitLab project and code-scaffold generation, CI/CD setup, Terraform-based staging and production infrastructure provisioning, and secure GPT-token storage in Vault. The scaffold also includes authentication, API documentation, observability, Redis and vector-database integrations, deployment pipelines, and a cookbook with organisational examples; the post reports that it has onboarded hundreds of GenAI applications and saves an estimated 1.5 weeks before teams begin their first feature.


### [Data access patterns for simple Stripe integrations](https://yomu.fyi/post/data-access-patterns-for-simple-stripe-integrations.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: Ben Smith
- Published: Nov 27, 2024
- Type: Explainer

The article examines how applications should store and access product data in simple Stripe integrations as requirements for security, performance, and scalability evolve. It compares using Stripe’s built-in product fields with a separate database, while explaining that publishable API keys cannot retrieve product details and that secret or restricted keys must remain server-side. A web backend or serverless function can proxy requests securely, while CloudFront caching reduces repeated calls and latency but requires an appropriate refresh cadence. For richer metadata, inventory, variants, or custom attributes, the article describes combining DynamoDB with Lambda and Stripe, using Event Destinations or webhooks to synchronize changes and weighing that flexibility against database overhead.


### [Managing multiple Stripe test environments from your AWS-hosted application](https://yomu.fyi/post/managing-multiple-stripe-test-environments-from-your-aws-hosted-applic.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: James Beswick
- Published: Nov 26, 2024
- Type: Explainer

Stripe sandboxes provide isolated test accounts that let teams manage multiple environments from one account. Unlike legacy test mode, each sandbox has separate data, its own API keys, and configurable user access, while up to five sandboxes can exist per account. They support simulated external events, fake balances, Test Payouts with API v2 keys, and CLI or SDK access by changing keys. For AWS-hosted applications, the recommended pattern stores sandbox and production keys in AWS Secrets Manager, using secret names as environment-neutral aliases rather than embedding environment logic in code. Teams can combine Stripe sandbox permissions with AWS IAM resource policies and directory groups to restrict which users or accounts can retrieve keys and prevent accidental production access.


### [Getting started with Stripe in the UAE: A comprehensive guide for developers](https://yomu.fyi/post/getting-started-with-stripe-in-the-uae-a-comprehensive-guide-for-devel.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: Soad Abuelnaga
- Published: Nov 25, 2024
- Type: Tutorial

The guide explains how developers can use Stripe for UAE-based e-commerce businesses, following its public debut in the country in April 2021. It covers Stripe Billing for recurring billing, Stripe Connect for marketplaces, Stripe Radar's machine-learning fraud protection, and the platform's support for Apple Pay, Google Pay, and more than 135 currencies including AED, BHD, and KWD. Account setup requires business details, KYC documentation based on entity type, and a linked bank account, with sole proprietors and free zone establishments allowed to use personal accounts under the stated conditions. The Dashboard supports payout and transaction tracking, customer and product management, real-time updates, data exports, tax configuration, and Payment Links, while UAE payouts are described as arriving in AED or USD on a T+5 business-day schedule.


### [How we reduced initialisation time of Product Configuration Management SDK](https://yomu.fyi/post/how-we-reduced-initialisation-time-of-product-configuration-management.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Ram Dilip Pradhan
- Published: Nov 22, 2024
- Type: Benchmark

GrabX, Grab’s central product configuration management platform, provides an SDK whose eventually consistent updates take about a minute to reach clients, but initialisation took roughly four minutes for services loading around 400 MB. The SDK’s sequential workflow downloaded subscribed-service and common data from AWS S3 to disk and memory before initialising dependent modules, creating cold-start pressure and possible throttling when new instances were launched. Phase 1 made the two data loads concurrent, reducing initialisation time by approximately 80%, while Phase 2 concurrently downloaded and loaded large configurations within a subscribed service, adding a further approximate 6% reduction. Phase 3 removed disk persistence because its stale-data fallback conflicted with most clients’ need for current data, allowing failed connections to trigger client action such as retrying. Benchmarks across services with varied data sizes indicated reductions of up to 90%.


### [Using demo data for testing Stripe integrations in AWS-hosted applications](https://yomu.fyi/post/using-demo-data-for-testing-stripe-integrations-in-aws-hosted-applicat.md)
- Company: [Stripe](https://yomu.fyi/company/stripe.md)
- Author: James Beswick
- Published: Nov 22, 2024
- Type: Tutorial

Stripe sandboxes let developers manage multiple test environments from one Stripe account for AWS-hosted applications, extending Stripe’s test mode with simulated external events, fake balances, and Test Payouts using API v2 keys. The post describes seeding a sandbox with products and other Stripe objects by exporting production data to CSV for import or generating records with the Stripe CLI and scripts. For local use, developers authenticate with stripe login, while CI scripts pass a sandbox key to each CLI request and can optionally delete the created products afterward. It recommends storing the key in AWS Secrets Manager, retrieving it at runtime through the AWS CLI or SDK, restricting access with IAM, avoiding logs and source repositories, and rotating keys; this lets CI scripts use sandbox data without exposing credentials.


### [Pumas, Routers & Keepalives—Oh my!](https://yomu.fyi/post/pumas-routers-keepalives-oh-my.md)
- Company: [Heroku](https://yomu.fyi/company/heroku.md)
- Author: Elizabeth Cox
- Published: Nov 21, 2024
- Type: Incident / postmortem

Heroku’s Router 2.0 beta exposed elevated tail response times and request failures in a subset of Puma applications, especially under 200 milliseconds of server-side lag and 30 requests per second. Investigation compared legacy and Router 2.0 connections, examined TIME\_WAIT behavior, and tested Go’s http.Transport idle-connection limit; raising MaxIdleConnsPerHost from the default of 2 to 100 stabilized connection states but did not improve latency. The underlying issue was Puma’s handling of persistent connections, where request balancing could leave work queued behind busy connections; disabling keepalives eliminated the problem, while thread, worker, and max\_fast\_inline tuning were offered as alternatives. Load tests found the issue unique to Puma, and the update reports that Puma 7.0 fixed the bug, recommending version 7.0.4 or higher.


### [Tips & Tricks for Migrating to Router 2.0](https://yomu.fyi/post/tips-tricks-for-migrating-to-router-2-0.md)
- Company: [Heroku](https://yomu.fyi/company/heroku.md)
- Author: Agne
- Published: Nov 21, 2024
- Type: Tutorial

Heroku Router 2.0 is generally available and is expected to become the default, making migration planning important before rollout. The guidance recommends creating a staging application, enabling the http-routing-2-dot-0 feature, restarting web dynos when needed, and checking response headers and system logs to confirm routing. Router 2.0 identifies requests with Via values such as “2.0 heroku-router” or “1.1 heroku-router,” and its logs add protocol, tls, and tls\_version fields. HTTP/2 is enabled by default on custom domains with valid TLS certificates, while HTTP/2 can be disabled through a Labs feature. Keepalives are also enabled between the router and web dynos, but applications using recent Puma versions may need the keepalive opt-out because of a connection-handling bug.


[Newer posts](https://yomu.fyi/posts/page/182.md) · [Older posts](https://yomu.fyi/posts/page/184.md)