All Articles
Designing Around Claude API 413 request too large — Preflight Sizing and Splitting
Pack too much text, images, and tool_result into one request and Claude API rejects it with 413 request too large. Here is a code-backed design for measuring request bytes before you send, telling the two kinds of 413 apart, and splitting requests without breaking them.
When You Give an API Key an Expiration Date, Expiry Becomes a Plan Instead of an Accident
The Console now lets you set expiration dates on API keys. Here is how to fold planned expiry into unattended operations — with overlapping dual keys and a local expiry ledger — so your nightly jobs never go dark.
A Long Non-Streaming Response Was Billed Twice Past the 10-Minute Wall: Redesigning the SDK's Default Timeout and Retries
The Anthropic SDK's default 10-minute timeout and two automatic retries can silently re-run a long non-streaming response and bill you twice. Here is how the trap works, and how to close it with streaming, explicit timeout/max_retries, and a small local ledger — with measured before/after numbers.
Is This New Wallpaper Too Close to One We Already Ship? Near-Duplicate Detection with a Perceptual-Hash Pre-Filter and Claude Vision
A two-stage pipeline that catches the near-duplicates a SHA256 hash misses — recolored, lightly cropped, re-encoded — by pre-filtering with a perceptual hash and adjudicating only the close pairs with Claude Vision. With measured precision calibration and cost design from running a wallpaper catalog solo.
Tightening Tool Schemas From the Arguments You See in Production
Record the arguments Claude actually passes to your tools in production, then use that distribution to add enums and patterns back into your JSON Schema. With logging code and before/after numbers.
When Whisper Wrote 'Thanks for Watching' Into the Silence — Measuring and Killing Japanese Transcription Hallucinations
Whisper inserts phantom boilerplate into silent or noisy segments of Japanese audio. Here is how to measure hallucinations with no_speech_prob and avg_logprob, strip silence with VAD, and have Claude validate what remains — with the implementation and the routine that pulled it back.
Don't Trust the Confidence Score: Per-Class Calibration and Abstain Routing for Vision Classification
Overall accuracy looked fine while individual categories quietly collapsed. Here is how I calibrated Claude Vision's self-reported confidence per class and routed abstentions to a human queue.
My Nightly Batch Was Quietly Running on a Bigger Model — Declaring Per-Task Model Ceilings and Enforcing Them
Scatter model names through your code and a cheap batch job will eventually run on an expensive model. Here is a manifest that declares a ceiling per task, a deny-by-default resolver, and a morning audit that catches drift — with working code.
Same Output, Different Path — Guarding Agent Trajectories with Invariants
When the default model changes, your final output can stay correct while the path your agent takes quietly shifts. Here is a trajectory regression harness built on recorded tool traces and deterministic invariants, with working code and measured numbers.
When the RAG Started Being Confidently Wrong — Field Notes on Measuring Retrieval Misses With Groundedness
In a Claude API RAG, the answers stay fluent while the facts drift. Often the cause is a silent recall decay on the retrieval side, missing the document that holds the answer. Field notes on measuring groundedness and retrieval hit rate and walking the system back, with working code and real numbers.
The 200K-Token Cliff That Doubled My Nightly Bill — A count_tokens Preflight to Avoid Long-Context Pricing
Sonnet 5's native 1M context switches the entire request to long-context pricing the moment input crosses 200K tokens. Here's how I caught that silent cost cliff before sending, using the billing-exempt count_tokens API, with working Python and TypeScript code.
Rolling Out Agent Behavior Changes Gradually with Feature Flags
When an unattended agent changes its prompt or behavior all at once, quiet regressions hide until morning. Here is a design for assigning new behavior to only a fraction of runs, keeping a control group, and adding deterministic bucketing, canary comparison, and automatic rollback.