Fallback Response For
Written later and filed to this date, as part of filling in every day of the year.
The first commit is two lines. A heading with the name, and one sentence under it: a middleware service that enhances language model requests with additional features, including fallback mechanisms, prompt optimizations, content filtering, and automatic switching between models during outages. Committed on a Friday afternoon at the end of August 2024, six months before the next repository in this workspace and the only one from that year, and then nothing. One file, one sentence, the whole repository.
Read the sentence as a specification and it is a good one. Four promises, and all four are the things you discover you need the first time a model you depend on goes away mid-afternoon. A fallback, so a request has somewhere else to go. Switching, so the next request does not have to fail first to learn that. Prompt optimization, because the fallback is a different model and will not read the same prompt the same way. Content filtering, because now there are two models answering in your name and only one of them was tested. The order in the sentence is the order you would build them in. Whoever wrote it had been through an outage, or had thought hard about one.
What it was for is in the name: one door in front of several models, so that the thing calling it never has to know which one answered.
The first code under that sentence, when it came, was a skeleton with the sentence’s shape and nothing else. A Go interface with five methods, one per promise and one for generation. Each method returned its own name. The generate call returned the string Generated response for: followed by the prompt. The fallback returned Fallback response for: and the prompt. The optimizer returned Optimized: , the filter Filtered: , and the model switch logged a line saying it was switching to a different model and returned success. The module path still carried a placeholder username. In front of all this stood a middleware chain six layers deep, logging, validation, error handling, authentication, rate limiting and cross-origin headers, guarding one route.
What it taught is the gap between those two artifacts. The sentence knew what resilience against a vendor outage requires. The skeleton knew what the sentence said, and answered every call by repeating the question with a prefix. There is no failover in a function that returns Fallback response for: plus your prompt; there is a place where failover would go, labelled correctly. The repository held the premise for over a year as a sentence, and the premise was right, and being right is not the same as having a second model to switch to.