add agents.md

Author: dsyme

AGENTS.md

@@ -0,0 +1,48 @@
+# Agent Guidelines
+
+## Release Notes
+
+Update `RELEASE_NOTES.md` when making user-visible changes:
+- Add entries under the `## [Unreleased]` section
+- Use categories: `### Added`, `### Changed`, `### Fixed`, `### Removed`
+- Include PR links: `[#123](https://github.com/fsprojects/FSharp.Formatting/pull/123)`
+
+## Code Formatting
+
+Format code using Fantomas before committing:
+
+```bash
+dotnet tool restore
+dotnet fantomas build.fsx src tests docs
+```
+
+Check formatting without modifying files:
+
+```bash
+dotnet fantomas build.fsx src tests docs --check
+```
+
+Configuration is in `.editorconfig`.
+
+## CI Checks
+
+Run these checks locally before pushing:
+
+```bash
+# Full CI pipeline (lint, build, test, docs)
+dotnet fsi build.fsx
+
+# Just lint and test
+dotnet fsi build.fsx -- -p Verify
+
+# Run analyzers (G-Research.FSharp.Analyzers, Ionide.Analyzers)
+dotnet msbuild /t:AnalyzeSolution
+```
+
+Individual steps:
+
+```bash
+dotnet restore FSharp.Formatting.sln
+dotnet build FSharp.Formatting.sln --configuration Release
+dotnet test FSharp.Formatting.sln --configuration Release --no-build
+```