Maryam Ariyan
Software engineer · systems architect

Maryam
Ariyan.

Eight years building high-scale infrastructure and AI tooling, developing the foundational components that millions of developers depend on to power the .NET ecosystem and GitHub Copilot.

Chapters

Early years
Astronomy olympiad · community · high school
expanding another day
Formation
B.S. Software Engineering · M.S. Computer Science
Publication: Terrain Synthesis Using Curve Networks
2017 – 2025 · Microsoft
.NET Libraries · GitHub Copilot · AI & IDE
This page · tap to explore
Now
Between chapters · deep work and research
$ maryam --what-are-you-cooking
The footprint — tap each
1.4 billion+
Logging installs
1.4 billion+ downloads. Zero runtime cost.
tap
In high-traffic services, log arguments were being evaluated and allocated in memory even when they'd be immediately discarded. I designed a Roslyn source generator that moves that work to build time — the optimized code is written before the app ever runs. Developers write a simple declaration, the generator handles the rest. Shipped in .NET 6, 1.4 billion+ downloads. design doc →  official docs →
+8%
Copilot accuracy
Code completion, unblocked for 5M+ users.
tap
I repurposed C++ offline evaluation scripts for C# to give the DevDiv research team the data needed for A/B model experiments. The result unblocked higher-accuracy model rollouts to 5M+ Copilot users.
~3×
Editor responsiveness
Razor files in Visual Studio, syntax coloring.
tap
Every time Visual Studio colored the text in a Razor file, it was silently running the full C# type-safety checker — a heavyweight analysis with no business being there. I tracked it down, convinced the compiler team to expose an API to skip it, and the editor got roughly three times faster at that operation for every developer working on Razor files. dotnet/roslyn #71036 →
~90%
Config allocations cut
Reflection-free configuration. Shipped in .NET 8.
tap
First, I optimized a legacy bottleneck in the .NET configuration engine, reducing allocations by ~90% (408B to 48B). I then designed the Configuration Source Generator to enable Native AOT by moving logic from runtime to build time. While I moved teams before the launch, my foundational implementation was integrated by the .NET team into the final .NET 8 release. dotnet/runtime #67186 →  .NET 8 announcement →
86%
ML triage accuracy
GitHub issue labeler across ~10 repos.
tap
I built an ML.NET bot to automate GitHub issue triage across dotnet/runtime, roslyn, aspnetcore and more. Reached 86% PR labeling accuracy. Built before ML tooling was a trend — because the manual burden was real.
−1.5h
CI build time
30+ libraries migrated to one repo.
tap
I ported 30+ Extensions libraries into dotnet/runtime while preserving commit history, removing dotnet/extensions from the product build critical path and cutting over 1.5 hours from CI build times across PR and official builds.

The invisible impact

When a developer configures an app's settings, injects a service into a controller, or reads a log line that saved a 3am incident — they're executing code paths I designed and maintained. The work operates at the plumbing level. Most people who depend on it have never heard my name. That was always the point.

Where the work lived

How focus shifted across the eight years

high low
2017 2019 2020 2021 2022 2023 2025
.NET Libraries / BCL
ML / automation
AI / IDE / Copilot

Commit distribution by repo

dotnet/runtime
65%
dotnet/aspnetcore
15%
dotnet/extensions
10%
dotnet/docs
5%
other
5%

Open source commits · .NET Libraries team only · 2019–2022

.NET 3350
.NET 5680
.NET 6850
.NET 7720
.NET 8910

Sustained output across five major release cycles. Moved to the Razor / Copilot team in late 2022 — separate codebase, different contribution model.

The range — tap each layer
2017–19Foundation — joining the team I used to file bugs against
I walked up to the .NET booth at Microsoft Build. Not applying — just talking about a real bug I'd found in .NET Core's long path support. Left with an interview. Joined the .NET Libraries team and began working on the sub-systems I had previously depended on as a developer. Early years: API additions, cross-platform fixes, OleDb port to .NET Core unblocking an estimated 15–20% of Windows Forms customers, ZLib security upgrade, macOS Mojave compatibility scouting.
C#.NET BCLcross-platform
2019–21Ownership — Microsoft.Extensions and ML-powered triage
I became the primary owner of Microsoft.Extensions — Dependency Injection, Configuration, Logging, Hosting, Options. The invisible layer wiring every modern .NET application. Delivered structured JSON console logging for .NET 5, adopted by Google Cloud. Built the ML.NET issue labeler bot — scaled from one repo to ten, 86% PR labeling accuracy — before ML tooling was a category. Promoted to SDE2.
Microsoft.ExtensionsML.NETAPI designOSS stewardship
2021–22Performance — source generators and zero-allocation .NET 6 & 7
I designed and shipped the Logging Source Generator — zero heap allocations, compile-time, driven by a requirement from the Microsoft Teams engineering team. Fixed a long-standing DI deadlock affecting multiple first-party teams. Added ValidateOnStart API. Built-in cache metrics for MemoryCache. Drove nullable reference type annotations across thousands of Microsoft.Extensions APIs. Authored the core Configuration Binder Source Generator for .NET 8.
Source generatorsSpan<T>.NET 6/7performance
2022–23Pivot — Razor tooling and IDE performance
I moved to Developer Tools. Added telemetry infrastructure, correlation IDs across LSP calls, and targeted tracing notifications — giving the team real-time visibility into regressions before they reached paying users. Drove A/B experiments for semantic token improvements, including one that revealed unexpected regressions caught and reversed quickly because the instrumentation was already in place.
RazorLSPtelemetryA/B experiments
2023–25AI — Copilot integration, eval pipelines, novel prototypes
I led the effort to make Razor a first-class citizen in the Copilot AI experience. Built SimCo — the offline eval pipeline for C#, repurposed from C++ scripts — enabling the research team to run A/B model experiments at scale. Shipped "Implement with Copilot." Built BugBuddy, an agentic AI prototype using RAG and OpenAI tool-calling, which leadership cited as the model for how DevDiv should explore AI. Built CarMob, a Teams AI chatbot for internal career mobility, 2nd place in an executive D&I hackathon. Role eliminated mid-2025 when the team restructured.
GitHub CopilotLLMsRAGVisual Studioeval pipelines
alwaysCommunity — Vancouver, mentorship, the work that doesn't commit
When others moved to Redmond, I stayed in Vancouver. Mentored new hires joining a distributed team. Organized and presented at MSVAN. Spoke at .NET Conf. Ran local .NET meetups and Q&A panels for developers outside Microsoft. Work that ran in parallel to the technical contributions, throughout my time on the team.
.NET ConfmentorshipVancouvercommunity
The arc — tap each year
2017
Joined the .NET Libraries team
Walked up to the .NET booth at Microsoft Build, talked about a real bug, left with an interview. Began working on the infrastructure I had previously depended on as a developer at Ciena.
2018–19
Foundation work across .NET Core 2.x and 3.0
API additions, cross-platform fixes, ZLib security upgrade, macOS Mojave scouting, OleDb port to .NET Core — unblocking an estimated 15–20% of Windows Forms customers from migrating.
2019
Took ownership of the GitHub issue labeler bot
Used ML.NET to automate issue triage across dotnet/runtime and ~10 major repos. Reached 86% PR labeling accuracy. Helped the ASP.NET team hit their .NET Core 3.0 release dates.
2020
Became primary owner of Microsoft.Extensions
Ported 30+ Extensions libraries into dotnet/runtime, cutting CI build times by 1.5+ hours. Delivered structured JSON console logging for .NET 5, adopted by Google Cloud. Promoted to SDE2.
2021
Logging Source Generator · DI deadlock fix · ValidateOnStart
Designed the Logging Source Generator for .NET 6 — zero allocation, compile-time. Fixed a long-standing deadlock in Dependency Injection. Added ValidateOnStart API. Publicly recognized by the team as the go-to expert for Microsoft.Extensions.
2022
Cache metrics · Config Binder Generator · moved to Razor team
Delivered built-in cache metrics for MemoryCache. Authored the core Configuration Binder Source Generator — the foundational implementation that shipped as a .NET 8 flagship feature. Moved to Developer Tools — Razor language tooling in Visual Studio.
2023
IDE telemetry · A/B experiments · .NET Conf demo
Built correlation ID infrastructure across Razor LSP calls. Set up targeted tracing notifications for real-time perf regression detection. Ran semantic token A/B experiments, caught and reversed a regression before it reached external users.
2024
SimCo · BugBuddy · CarMob · Implement with Copilot
Shipped offline eval pipeline for C# (SimCo), proving +8% code completion accuracy. Led Razor's AI integration. Shipped "Implement with Copilot." Built BugBuddy — agentic AI prototype praised by leadership. Built CarMob Teams chatbot, 2nd place in D&I executive hackathon.
mid-2025
Role eliminated · team restructured
The team restructured. My role was eliminated. Eight years, five .NET versions, two teams, and a pivot into AI tooling — complete.
How I work — tap each
works below the surface
reads the source
measures before claiming
ships incrementally
works between codebases
builds tools that don't yet exist
Most of what I work on lives below the product — configuration, logging, dependency injection, build pipelines. Pieces that 1.4 billion+ runtimes depend on without anyone naming. The framework is supposed to feel reliable; I'm not supposed to be visible. That's by design.
Most of the work was debugging things other people wrote, in codebases nobody fully understood. I stay in the source until the mystery disappears. That's the whole method.
I added cache metrics, built A/B experiment infrastructure, instrumented LSP calls with correlation IDs. Every claim backed by telemetry. A performance improvement that isn't measured isn't an improvement.
I learned early that shipping a complete feature in one massive PR increased risk and churn for reviewers. Moved to deliberate, incremental delivery. Smaller changes, more trust, less rework.
The work crossed codebases. I coordinated across .NET Libraries, ASP.NET, R9 (Teams backend), Roslyn, and DevDiv research simultaneously. The cross-codebase work that doesn't show up in a single repo but is often what makes a feature actually ship.
Built the ML.NET issue labeler before triage tooling was a category — 86% PR labeling accuracy across ~10 .NET repos. Built BugBuddy, an agentic AI prototype using RAG and tool-calling, before "agentic" was a buzzword — recognized internally as a model for how DevDiv should explore new AI experiences. The pattern: see the gap, build the missing thing.
Community · built in the open

A proven open source maintainer. Day-job work surfaced publicly through three channels — receipts below.

YouTube content

On the official .NET YouTube channel and product demos.

Blog posts

Official Microsoft DevBlogs and independent writing.

Code submissions & demos

Reference code shipped for others to learn from and ship against.

What colleagues said — tap each
"You did an extremely good job navigating the strong opinions of 3 Partner Software Engineers..."
"You did an extremely good job with the logging source generator. It was very tricky to navigate the strong opinions of 3 Partner Software Engineers (myself included) and drive clarity with that design document you wrote in dotnet/designs."
David Fowler · Distinguished Engineer, Microsoft
"Many of the design choices you drove set precedent in how our team writes source generators..."
"You did a terrific job delivering the Microsoft.Extensions.Logging source generator. Many of the design choices you drove for the feature set precedent in how our team writes source generators... my work on the JSON generator was easier because I had you to seek design insight from."
Layomi Akinrinade · Software Engineer, .NET Libraries, Microsoft
"Your Bug Buddy prototype gets lots of praise as an example of how DevDiv should explore new Copilot experiences..."
"Your Bug Buddy prototype gets lots of praise as an example how we in DevDiv should explore new Copilot experiences. I've seen in meetings more than once how this spurred other teams to think about how to apply this new AI technology."
Lutz Roeder · Principal Software Engineer, Microsoft · CoreAI / Dev AI Incubation
"You have been relentless in your work on Code Mapper for Razor..."
"Maryam, you have been relentless in your work on the Code Mapper for Razor and Razor integration with Copilot in general. This is an incredibly challenging task, especially since you had to pick up work from two different people and learn on the go. Your dedication and ability to adapt are impressive."
Oscar Obeso · Senior Software Engineer, Microsoft
"People started to count on you in the Microsoft Extensions areas..."
"In the last few months especially during the .NET 6.0 cycle, I noticed great growth demonstrated by you. I have noticed you have built more experience in the Microsoft Extensions areas and people started to count on you in such areas — e.g. logging, hosting."
Tarek Sayed · Senior Software Engineer, Microsoft .NET

Eight years.
One chapter of many.

If the work resonates — the range, the depth, the fact that I was building agentic AI tooling before it had a name — I'm reachable. Not performing a search.

open to the right conversation · not performing availability · somewhere in a different timezone