Writing

Is It a Regression, or Just a Flaky Test? Teach Your CI to Tell the Difference

A red build tells you something failed. It doesn't tell you the thing that matters — whether a human needs to fix it now, or whether the test will be green next run. Here's a small, dependency-free flake engine that answers that from run history.

A False Signal Is Worse Than a Missed One: Citing and Abstaining in LLM Document Extraction

When you turn public documents into sales signals with an LLM, the expensive failure isn't the signal you miss — it's the one you invent. Two disciplines fix it: cite every signal, and abstain when the document supports nothing.

When ‘Compliant’ Is a Legal Claim: Computing EUDR Deforestation Risk — and Knowing When to Abstain

Scoring forest loss inside a plot boundary is the easy half. The engineering that matters is refusing to certify on bad geodata.

Data Sovereignty Is an Access-Control Pattern (and It Should Fail Closed)

Turning ‘the community owns its data’ into enforceable, audited code: default-deny access, owner-granted sharing, no super-role, and an append-only audit trail.

When Not to Answer: Building a Voice-Over-Email Loop With a Consent Gate

A small, runnable prototype of a voice product over email — transcribe, LLM reply, synthesize, thread back — and why the most important line of code is the one that refuses to speak.

Knowing When Not to Make the Highlight Reel

Ranking, dedup, and the senior instinct to refuse — building a camera-roll video picker.

Flip One Byte and the Whole Chain Knows

Building a tamper-evident, hash-chained log and the verifier that makes it worth anything — and what real end-to-end voting adds on top.

Measure the Aggregate, Never the Person: Privacy-Preserving Analytics with a k-Anonymity Gate

Most analytics ships a re-identifiable event log to a server and aggregates there. Here's the inversion — aggregate on-device, and refuse to report any cohort small enough to single someone out.

Fail-Open or Fail-Closed: The One Decision Every Piece of Edge Middleware Has to Make

When the edge state store goes down, your middleware has to choose between letting traffic through and blocking it. That choice is a design decision, not a default.

The Audit Log That Can't Have Holes

Building a gap-free, append-only compliance ledger in Elixir/Phoenix — why the obvious approaches all fail, and the one pattern that survives a regulator.

The Authorization Gate: Modeling Multi-Party Workflows in Rails

Four parties, one work order, and the single invariant that keeps money and compliance from leaking out of the seams.

The LLM Suggests. The Rules Engine Decides.

Why a compliance or money classifier keeps a deterministic core — and puts the model behind an abstain gate.

Streaming a Conversational-AI Trainer — and Teaching It to Say 'I Don't Know'

How to stream an LLM roleplayer over Server-Sent Events, and why the debrief that scores a trainee should abstain instead of inventing a number.

Designing a Fail-Closed Access Gate in TypeScript

A worker walks up to a turnstile. Should it open? The safe answer to that question is a small, pure, boring function — and a tamper-evident record of every time you asked.

Never Trust the Model's Answer Key

Validating LLM-generated assessment content deterministically before it reaches a student

The Honest Answer Is Sometimes 'Not Enough Data'

Normalizing heterogeneous financial data with provenance — and building a gate that refuses to score a thin file.

The Number Was Green, So the Agent Stayed Quiet

Putting an eval harness and an abstain gate around an LLM analysis agent so it's trustworthy on noisy marketing data

A Staffing Forecast Without a Confidence Interval Is a Liability

Why a next-shift census model has to ship uncertainty, defer on thin data, and prove itself against a naive baseline before anyone staffs a floor from it.

The Agent Wanted to Call It Healthy. I Made It Abstain.

Shipping real software with coding agents, where the value is the judgment layer on top.

The Self-Healing Scraper That Refuses to Trust Itself

Letting an LLM repair a broken selector is easy. The engineering is in refusing to believe it.

The Best Thing an Observability Agent Can Say Is 'I Don't Know'

Giving an LLM observability assistant an eval harness and an abstain gate so it never invents a root cause on noise.

Never Bill a Sentence the Chart Didn't Write: Evidence Gates for Clinical Charge Capture

Why an AI that finds missed hospital reimbursement has to cite the chart and abstain — and why that guardrail belongs in deterministic code, not in a prompt.

The Query That Got 30× Faster Without Changing Its Answer

A patient-journey analytic over a claims graph, taken from a naive plan to a materialized-view rollup — with the one rule that separates an optimization from a bug.

Building a Client SEO Dashboard in React

Retry Backoff You Can Actually Test

Exactly-once is a lie, so every remote call needs retries with jitter — but jitter is exactly the part that's hard to assert on. backofflite separates the pure backoff policy from the impure retry loop, with a seedable RNG and an injectable time.sleep, so the AWS full/equal/decorrelated jitter strategies and the whole retry path are deterministically unit-testable.

A Sans-I/O SSE Parser for Python

The "sans-I/O" idea behind h11 applied to Server-Sent Events: a parser that does zero networking, so you can feed it bytes from httpx, aiohttp, or a raw socket and get fully-parsed events. sansio-sse implements the WHATWG event-stream rules — and the whole correctness story lives in the chunk boundaries, like a CRLF split across two reads.

A Ruby Backend for the Vercel AI SDK

The Vercel AI SDK's useChat / useObject hooks speak a language-agnostic Data Stream Protocol — with official backends for JavaScript and Python, but none for Ruby. ai_stream is the missing piece: stream text, reasoning, tool calls, sources and custom data parts to the frontend from a Rails or Rack app.

Compiling Bash Globs into Ruby Regexps

Ruby's glob support is for files on disk; JavaScript has picomatch/minimatch for arbitrary strings, and Ruby had no clean counterpart. picoglob compiles *, **, braces, ranges and extglobs into a reusable Regexp — and the correctness lives in the edge cases.

Fuzzy-Match Scoring in Ruby, with Highlights

Ruby's fuzzy gems do record-linkage or a boolean match; none return a relevance score and the matched positions you need to highlight a command palette. fzy_score is a faithful port of fzy's scoring — and it powers the ⌘K palette in our own Hotwire demo.

Saying "Hey Claude" Out Loud, On-Device

Could you say "Hey Claude" and have a coding agent start working — without streaming your mic to the cloud all day? The progressive-gating pipeline, the wake word we trained from scratch, and the macOS permission story underneath it.

Building a Multilingual Speech Corpus, Verified by Whisper

Public audio is plentiful and filthy. The dedup, the Whisper verification gate, and the immutable edge-served manifest behind LinguaGuessr — and why the same playbook applies to invoices and sensor data.

Postgres Indexing for Rails at Scale

Composite-index column order, partial indexes, reading EXPLAIN ANALYZE, and the counter-cache trade — the indexing decisions that start to matter once a table outgrows memory.

Sidekiq Idempotency and Reliability Patterns

Exactly-once is a lie. Once you accept that every job can run twice, the patterns that keep background work correct — idempotency keys, dedup, retries with backoff, and a deliberate dead set — fall into place.

Zero-Downtime Migrations at Scale

A schema change that is one line in development can take an ACCESS EXCLUSIVE lock and freeze a busy table in production. The locks, the backfills, and the multi-deploy choreography that keep the app up while the schema moves.

Hunting N+1 Queries Systematically

Bullet, Prosopite, and strict_loading are not competing tools — they cover three different stages of the same problem. Here is how to use all three.

Rails Caching Done Right

Russian-doll fragment caching, low-level Rails.cache, and key-based expiration — the caching model where you almost never write an explicit expire, because the keys do the work for you.

Real-Time UI Without React

A Turbo Streams + Stimulus pattern that gives you live updates, optimistic interactions, and zero client-side state to keep in sync.

A Petabyte, a Bill, and a Tiering Decision

How we cut an S3 line item ~60% without breaking a single user workflow.

The Support Tool That Replaced Itself

Building an MCP server so Claude Desktop could edit production data safely.

The Hidden Cost of `mount Admin::Engine`

What we learned migrating a generated admin to React + GraphQL.

The ERP That Will Only Talk to You by Email

A production integration built on AWS SES, a job queue, and compound indexes.

One UIConfig, Four Runtimes

A production server-driven UI across iOS, Android, React, and React Native.

Skills, Not Chatbots

Building an internal AI plugin system for an engineering team.

The Monorepo Was for the Agents

Cross-team context for AI agents without a real migration.

319 N+1s, 5,940ms Wasted

Auditing a decade of Rails code in one afternoon.

The Page That Counted 800 Million Rows

When aggressive denormalization is the right answer.

The Question the AWS Console Will Not Answer

RDS IOPS pattern detection with Ruby and a spreadsheet.

S3 Access Log Archaeology

Turning a year of access logs into an archival policy.

One Commit, Six Lessons

A Salesforce sync, a read follower, and the audit that reshaped a credentials posture.

The Support Tool That Edits Five Tables Atomically

A reparent-user workflow with a dry-run diff.