Four engineers, one invoicing product, no QA team. This is the risk-based testing strategy we settled on: integration tests over mocks, contract tests at service edges, a handful of E2E happy paths and test data that does not rot.
Our player character stuttered against the background whenever the camera followed it, worst on 144 Hz monitors. Movement wrote the transform in Update, the camera read physics positions, and interpolation was off. How we measured the jitter and fixed all three.
When a server is slow and the dashboard is vague, a dozen standard commands narrow the problem to CPU, memory, disk, network or a single process in about five minutes. This is the order we run them in and how we read each output.
Our dosing controllers ran for weeks, then locked themselves out on day 49. The interval check compared now >= lastRun + interval, which breaks when the sum wraps past 2^32 milliseconds. How we proved it with a simulated clock and fixed it with unsigned subtraction.
A pipeline you are afraid to re-run is a pipeline that will eventually corrupt data. This guide covers partition overwrite, MERGE upserts, dedup keys, watermarks and why exactly-once is a property you build, not a setting you enable.
We switched our semantic search to a cheaper 1024-dimension embedding model and every insert and query failed against the 1536-dimension column. Worse, the half-finished fix would have mixed incompatible vectors. How we migrated with versioned columns, a backfill and dual reads.
A field guide to receiving webhooks reliably: verify signatures on the raw body, respond fast, queue the work, deduplicate by event ID, tolerate out-of-order delivery, replay safely and monitor the whole pipeline. With code you can adapt.
Our LLM bill tripled in one month and nobody could say which feature caused it. This guide covers what we built since: per-feature token accounting, prompt and response caching, model routing, output limits, batch processing and budgets with alerts.
In a red-team exercise our support agent read a customer-uploaded PDF with hidden instructions and drafted an email with another customer's order details. No data left the building, but the flaw was real. How we contained it with least privilege, confirmation and output checks.
The pre-launch security checklist we run on every new web app, organised by the OWASP Top 10:2025 categories: authorization tests, injection, secrets, headers and CSP, supply chain, error handling and logging, each with a concrete check you can automate.
We launched local pricing in JPY, KRW and VND and a customer in Osaka was charged 398,000 yen for a 3,980 yen course. Our code multiplied every price by 100 before sending it to Stripe. How we found it, refunded it and built a per-currency exponent table with tests.
Page 1 of our activity feed loaded in 9 ms, page 4,000 in 3.2 seconds, and a partner's sync job was walking every page. OFFSET makes Postgres read and discard every earlier row. We switched to keyset pagination with a tie-breaker and a matching index.
Most review comments are about naming and style, while the bugs walk past. How we review for correctness instead: follow the data, probe edge cases and error paths, look for races and trust boundaries, keep PRs small and hand style to machines.
A summary of Cloudflare's official postmortem for the November 18, 2025 outage: a database permission change doubled a generated feature file, which crossed a hard limit and crashed the proxy. Plus the lessons we are applying to our own config pipelines.
A customer changed the number in an invoice download URL and got someone else's PDF. The endpoint looked up invoices by sequential ID with no ownership check. We scoped every query to the account, added an object policy and cross-tenant tests.
A practitioner's reading of AWS's official summary of the October 19-20, 2025 us-east-1 disruption: a race in DynamoDB's DNS automation left an empty record, and recovery cascaded through EC2, NLB and Lambda. What happened per the report, and what we changed.
We once spent two weeks optimizing SQL for an endpoint whose real cost was a logging call. Since then every performance task starts with a profile. Here is how we capture flame graphs in PHP, Node.js and Python, how to read them, and how to measure the win.
Our greenhouse sensor boards boot-looped the moment WiFi.begin() ran, logging Brownout detector was triggered. The 3.3 V rail sagged under Wi-Fi transmit peaks from an undersized LDO and thin cable. How we measured it, fixed the power path and why disabling the detector is the wrong fix.
Most HTTP bugs can be pinned down with one tool you already have. This guide shows the curl options we use daily: verbose output, header-only requests, --resolve and --connect-to for testing servers before DNS changes, timing breakdowns, protocol versions and TLS checks.
Our MySQL primary hung and then aborted with the data volume at 100%. Binary logs had grown to 410 GB because a backfill tripled write volume while retention had been raised for a lagging replica. How we recovered, purged safely and stopped it recurring.
After we set "type": "module" in package.json, jest.mock stopped replacing our mailer and tests started calling the real SMTP client. Static ESM imports are linked before any mock runs. Here is the mechanism and the fix with unstable_mockModule.
Requests decide where a pod is scheduled and how much CPU it is guaranteed; limits decide when it is throttled or killed. This guide explains QoS classes, CFS throttling and OOM kills, and shows how we size containers from real metrics with HPA and VPA.
Our partner OAuth server matched redirect_uri by prefix, and our login page followed any next URL. Chained together with a legacy implicit flow, an access token could land on an outside domain. We moved to exact matching, relative-only next and code plus PKCE.
Our docs assistant answered v4 questions with v3 settings, fluently and with citations. Fixed-size chunking split tables from their headings, chunks carried no version metadata and we had no retrieval eval. How we rebuilt chunking, added filters and hybrid search, and measured it.
Our AWS bill jumped by over 9,000 USD in one month and nothing looked broken. The cause was NAT Gateway data processing: batch jobs in private subnets were reading S3 and pulling ECR images through NAT. VPC endpoints cut that line item by 94 percent.