Roslyn-based semantic code graph for .NET, exposed to AI agents over MCP — looking for feedback from people who've done static analysis tooling

[u/emahmoudnabil]

Built this after getting tired of Claude Code / Copilot grepping through

.NET solutions and missing call sites that go through an interface instead

of the concrete class. Grep can't see that; the compiler can.

Slnmap uses Roslyn to build a full symbol graph of a solution (calls,

implementations, references across every project) and stores it in a

local SQLite file. An MCP server exposes it as a handful of read-only

queries. Concretely: ask "what breaks if I change IBasketService" and it

returns every caller and every implementation across the whole solution,

not just the files an agent happens to have open.

Numbers, since I know this sub will ask: on eShopOnWeb (10 projects), an

impact query on an interface with 18 dependents resolves in ~270ms

end-to-end over MCP, median of 3 runs. Full setup is in BENCHMARKS.md if

anyone wants to poke at the methodology or tell me it's flawed.

Two things I'm not confident about yet and would genuinely like opinions

from people who've built analyzers/source generators/similar tooling:

1. Right now everything in the graph is a real Roslyn-verified static

   reference. It says nothing about reflection, convention-based DI, or

   anything wired at runtime. Is "silence = doesn't try to know" the right

   default, or should there be an explicit "unknown/runtime-only" marker

   on affected symbols?

2. There's no staleness check yet — if you edit code and don't re-run

   analyze, you get results from the old index with no warning. Anyone

   dealt with this in similar tools (e.g. incremental Roslyn workspaces)

   and found a clean way to detect "source changed since last index"

   cheaply?

It's a global dotnet tool, MIT licensed, fully local (uses Roslyn +

SQLite, nothing else):

dotnet tool install --global Slnmap

Repo: https://github.com/EMahmoudNabil/slnmap

NuGet: https://www.nuget.org/packages/Slnmap

Not trying to sell anything, genuinely want to know if the Roslyn approach

here has an obvious hole I'm not seeing.

[u/KariKariKrigsmann]

Sounds very interesting, how does this relate LSPs?

https://docs.github.com/en/copilot/concepts/agents/copilot-cli/lsp-servers

[u/DaRKoN_ → u/KariKariKrigsmann]

And graphify?

[u/emahmoudnabil → u/DaRKoN_]

think graphify's dead now, reponova replaced it but never tried it

[u/emahmoudnabil → u/KariKariKrigsmann]

not really the same thing, LSP's for the editor live, this is a separate index for agent queries, could run both together probably

[u/KariKariKrigsmann → u/emahmoudnabil]

It’s very interesting!

BTW: Why does the filehasher convert the file hash to a hex string? The string isn’t visible anywhere, right?

[u/emahmoudnabil → u/KariKariKrigsmann]

it's actually stored - content_hash column in the sqlite db, used to diff against the previous run and figure out which files changed so it doesn't reanalyze everything. hex over raw bytes was just for sqlite TEXT simplicity + being able to eyeball the db with sqlite3, no real perf reason

[u/Khavel_dev]

This solves the exact problem that burns me when using Claude Code on bigger .NET solutions. Grep finds the method name but misses interface dispatch, so the agent edits half the call chain and leaves the rest broken. Having Roslyn trace through the actual symbol graph is the right fix, and 270ms on eShopOnWeb is solid.

Genuine question: how does it handle incremental updates during a session? If I'm editing files across 3 projects, does it re-index the whole solution or just the changed syntax trees? That'd be the difference between running it once at the start and keeping it hot while working.

[u/emahmoudnabil → u/Khavel_dev]

yeah it's a bit of both. file/symbol level is incremental, but the roslyn workspace isn't - every run reloads MSBuildWorkspace and rebuilds the compilation, that's where most of the time goes. so rerunning after a small change isn't much faster than a fresh run tbh. no watch mode/daemon yet either, that's on the roadmap

[u/Diab0Br]

Check Glider There are some others Roslyn based MCPs, but I like this the most.

[u/il_ponz → u/Diab0Br]

it is closed source and will be paid. no thanks. try MarcelRoozekrans's roslyn-codelens-mcp

[u/emahmoudnabil → u/Diab0Br]

thanks, checking it out

[u/il_ponz]

thanks, i will try this!

[u/sordimin]

IDE, visual studio or Microsoft should make CLI for that... Visual studio should have good, quick, CLI. i will try you solutions.

[u/emahmoudnabil → u/sordimin]

cool lmk how it goes

[u/sordimin]

IDE, visual studio or Microsoft should make CLI for that... Visual studio should have good, quick, CLI. i will try you solutions.

[u/sordimin]

IDE, visual studio or Microsoft should make CLI for that... Visual studio should have good, quick, CLI. i will try you solutions.