Sidemark: Active Telemetry Comments for C#

OpenTelemetry has quietly become table stakes. That's a good thing, but if you've instrumented a real codebase, you know the tax. A method that does one obvious thing slowly fills up with StartActivity , SetTag , AddEvent , SetStatus . The bookkeeping of telemetry starts to drown out the intent of the code, and in review you spend half your time mentally separating "what this code does" from "what we report about what it does." It's easy to think "oh, but the framework takes care of this with auto-instrumentation", but if you talk to the experts in OTel, they'll go to great lengths to explain that auto-instrumentation is a floor, not a ceiling. Most of the value in telemetry comes from the custom instrumentation you add to your code that adds business context to your traces. And that custom instrumentation is the stuff that clutters up your code. Here's the kind of thing I mean: // before - ugly, obtuse, who put that there var orderId = order . Id ; Activity . Current ?. SetTag ( "orderId" , orderId ); Sidemark is my answer to that code-obfuscation problem: non-invasive instrumentation via what I'm calling Active Comments . // after - glorious, beautiful, basking in the light of the sun, closer to god, happy, satiated var orderId = order . Id ; //? The idea A small set of comment syntaxes - //? , //! , //?! - become ride-along annotations . They travel next to the code, get read at build time, and turn into the equivalent Activity calls in the compiled output. The code you read stays the code that does the work. The telemetry rides along instead of competing with your logic for attention. The framing is loosely inspired by Wallaby.js's Live Annotations , which project runtime values inline next to the code that produced them. Sidemark takes the same instinct in the other direction: comments as a write surface for instrumentation, rather than a read surface for debug values. Comments are an under-used channel for information about code that isn't itself code - and su