All Articles
I Edited One Line of a Tool Description and the Whole Prompt Cache Rebuilt — Where to Place cache_control Breakpoints
Hit rate suddenly flatlined at zero because a volatile block sat upstream of stable ones. This walks through how prefix-cache cascade invalidation works, how to reorder blocks from stable to volatile, and where to spend your four cache_control breakpoints — with code and decision tables.
I Watched an Agent Try to Fix a File It Had Already Fixed — Stale Shallow Clones and Refreshing Before You Decide
An unattended agent tried to re-fix a file it had already fixed. The cause was a days-old shallow clone it kept reading. Here is how to detect that staleness numerically and re-clone only before decisions.
What I Decided the Day the Ceiling Doubled: A Headroom Budget for Scheduled Jobs on One Shared API Key
Why I did not compress my intervals when the rate limit doubled, and how to design a headroom budget for running several scheduled jobs on one shared API key, with measurement and working code.
When Stripe's Bill and Your Own Ledger Drift Apart: Field Notes on Metered Billing for Claude API
Usage-based billing for Claude API looks clean until month-end, when Stripe's total and your own usage ledger quietly disagree. Here are the field-tested patterns for idempotent meter events, reconciliation jobs, and pricing-change-proof credits.
Working Between Claude Design and Claude Code — Splitting Diverge and Converge
Rough design in Claude Design, fine detail in Claude Code. Now that the two live close together in the desktop app, here is how to run them as a divide-of-labor between diverging and converging — bridges like Link Local code and Send to included.
My Morning Batch Was Missing the Prompt Cache Every Time — Warming Cadence and the Break-Even Math for the 1-Hour TTL
Jobs that run a few hours apart cold-miss the prompt cache even with a 1-hour TTL. Here is how to back out the right warming interval from the TTL, and how to write the break-even formula that decides whether warming pays off — with numbers from a four-site daily generation pipeline.
When Thinking Is Always On, Prefill Quietly Stops Working — Fixing Streaming and Token Budgets for Fable 5
Fable 5 thinks by default. Prefill no longer applies, the first streamed block isn't text, and max_tokens has to leave room for reasoning. Here is how I fixed those three broken assumptions in my own automated publishing pipeline.
When the Same Model Has a Different Name Everywhere — Designing a Cross-Provider Model Identity Resolver for Claude
Now that Fable 5 is available on the API, Bedrock, and Vertex at once, the same model carries a different identifier on each. Here is how to untangle hardcoded model strings with a small resolver that maps logical names to physical IDs, carries capability flags, and verifies identifiers at startup.
An Unattended Agent That Wakes Up to a Blank Machine Every Time
A scheduled, unattended agent wakes up on a fresh disposable machine every run: paths it cannot write to, a filesystem that has not finished booting, a working directory that has vanished. Here is how to design state recovery into the first thirty seconds, drawn from real operational logs.
When Claude API Prompt Caching Quietly Stops Hitting in Production — Field Notes on TTL and Measured Savings
Prompt caching works beautifully the day you ship it, then quietly stops hitting in production. The five things that break the prefix, how to choose between 5-minute and 1-hour TTL, and how to measure real savings from usage instead of guessing.
Stopping an Unattended Writer From Publishing the Same Article Twice
When a Cowork scheduled task generates articles every day, the real danger isn't a crash — it's quietly publishing a piece that overlaps with one from a few days ago. Here is a gate that compares slug similarity and the day's log before publishing, built from a near-miss I caught this morning.
Your Claude Files API Storage Is Quietly Filling Up — Dedup With a Content-Hash Ledger and Reap the Orphans
Use the Files API in an automated pipeline and the same file gets uploaded again and again while orphaned files pile up unnoticed. Here is a content-hash dedup ledger plus an orphan GC design, with working code.