chore: add AGENTS.md

AGENTS.md

@@ -0,0 +1,32 @@
+# AGENTS.md
+
+## Development Commands
+
+- Build: You should not run build command.
+- Test: `go test -ldflags="-checklinkname=0" ...`
+
+## Documentation
+
+Update package level `README.md` if exists after making significant changes.
+
+## Go Guidelines
+
+1. Use builtin `min` and `max` functions instead of creating custom ones
+2. Prefer `for i := range 10` over `for i := 0; i < 10; i++`
+3. Beware of variable shadowing when making edits
+4. Use `internal/task/task.go` for lifetime management:
+   - `task.RootTask()` for background operations
+   - `parent.Subtask()` for nested tasks
+   - `OnFinished()` and `OnCancel()` callbacks for cleanup
+5. Use `gperr "goutils/errs"` to build pretty nested errors:
+   - `gperr.Multiline()` for multiple operation attempts
+   - `gperr.NewBuilder()` to collect errors
+   - `gperr.NewGroup() + group.Go()` to collect errors of multiple concurrent operations
+   - `gperr.PrependSubject()` to prepend subject to errors
+6. Use `github.com/puzpuzpuz/xsync/v4` for lock-free thread safe maps
+7. Use `goutils/synk` to retrieve and put byte buffer
+
+## Testing
+
+- Run scoped tests instead of `./...`
+- Use `testify`, no manual assertions.