Engineering
A New Enum Value Breaks Clients That Trusted Your List
A new enum value passes every schema diff and still breaks clients that validate responses. Read as text, send from a closed list, and mark it Breaking.
Oct 7, 2026
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Architecture
16 posts
AI & Automation
Failed Is Not a Terminal Status: A Contract for Agents
A run can fail on our own timeout while the paid work can still finish. Why an agent should not treat failed as a terminal status without a reason it can read.
Oct 6, 2026
Startup Ops
What One Second of AI Video Costs Us, Layer by Layer
One clip passes through five paid layers. We measured one of them with a wallet. The rest are price lists and estimates, and that gap is the honest answer.
Sep 24, 2026
Engineering
The Bill Is Authorised by Delivery, Not by Your Spend
Paying a vendor feels like it should authorise charging the client. It does not, and the wording that says it does once billed 900 credits for a video that did not exist.
Sep 18, 2026
Startup Ops
The Cheapest Way to Run an AI Product Is to Not Pay for It
Three products now let the user's own Claude plan pay for inference. Anthropic's terms permit one shape of that and ban another, and you cannot tell which.
Sep 17, 2026
AI & Automation
We Shipped an Agent-Native API Without OpenAPI
No /openapi.json, no generator, no spec to drift. The machine-readable entry point is the MCP server's tools/list — and that turned out to be the honest choice, not the lazy one.
Sep 17, 2026
Engineering
Negotiate the Format Before You Pay the Vendor
A 3% aspect mismatch is a rounding error. A 40% one is a different video. The threshold between them decides whether you refuse before the bill or apologise after.
Sep 16, 2026
AI & Automation
Never Answer an Agent With a Silent Substitution
An unmet parameter should come back named. We learned why the hard way: two warnings went missing for weeks and every test stayed green.
Sep 15, 2026
Engineering
One Reviewer Approved It. The Other Found the Bug.
Six blockers across four consecutive stories, and the two reviews agreed on one of them. Here is what running both actually cost us, and the rule we ended up with.
Sep 14, 2026
AI & Automation
Your Agent Can Branch on a Refusal. It Cannot Branch on a Warning.
Refusals in our API carry stable codes. Warnings carry none, on purpose — and the bug that proved why cost us two warnings nobody noticed were missing.
Sep 12, 2026
Engineering
Your Container Lies About Its Size, and Your Library Believes It
Our render container reported 32 cores when it had 4. Remotion sized its defaults from that and OOMed. Five confident diagnoses died before the answer turned up in a version field nobody had thought to print.
Sep 3, 2026
Engineering
We Charged 900 Credits for a Video That Didn't Exist
Our billing rule said: failed run after a paid vendor call means we charge. It sounded fair. On a run that only paid for speech, it was false, and it cost a customer.
Sep 3, 2026