✨ Implement core waiterr package with initial functionality and tests.

.gitignore

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+build/
+.task/

.golangci.yaml

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+version: "2"
+
+linters:
+  enable:
+    - errcheck
+    - govet
+    - ineffassign
+    - staticcheck
+    - unused
+    - copyloopvar
+    - dupl
+    - err113
+    - errname
+    - exptostd
+    - fatcontext
+    - funlen
+    - gocognit
+    - goconst
+    - gocritic
+    - gocyclo
+    - godot
+    - godox
+    - gosec
+    - perfsprint
+    - testifylint
+  settings:
+    testifylint:
+      enable-all: true
+      disable:
+        - require-error
+    gocognit:
+      min-complexity: 16
+    gocyclo:
+      min-complexity: 15
+    gocritic:
+      enable-all: true
+      settings:
+        hugeParam:
+          sizeThreshold: 255

AGENTS.md

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+# Agent Guidelines for waiterr
+
+This document outlines the conventions and commands for agents operating within the `waiterr` Go project.
+
+## Build/Lint/Test Commands
+
+- **Lint:** `task lint`
+- **Test All:** `task test`
+- **Test Single File:** `go test -run <TestName> <path/to/file_test.go>` (e.g., `go test -run TestNewHappy ./ezcache_test.go`)
+- **Format:** `task fmt`
+
+## Code Style Guidelines
+
+- **Module**: `codeberg.org/danjones000/waiterr`
+- **Go version**: 1.24.9
+- **Imports:** Group standard library imports separately from third-party imports.
+- **Formatting:** Adhere to `go fmt` standards.
+- **Naming Conventions:**
+    - Variables: `camelCase`
+    - Functions/Methods: `CamelCase` (exported), `camelCase` (unexported)
+    - Packages: `lowercase`
+- **Error Handling:** Return errors explicitly. Check errors immediately after a function call that returns an error.
+- **Linter Rules:** Refer to `.golangci.yaml` for detailed linting rules.
+- **Testing**:
+    - Use `github.com/nalgeon/be`
+    - Tests should be in a separate package, such as waiterr_test
+
+## Git Commit Guidelines
+- **Format**: Prepend commit messages with a gitmoji emoji (see https://gitmoji.dev)
+- **Style**: Write detailed commit messages that explain what changed and why
+- **Examples**: `✨ Add JSON export functionality for log entries`, `🐛 Fix date parsing for RFC3339 timestamps`, `📝 Update README with configuration examples`
+
+## Git Flow Workflow
+- **Main branches**: `stable` (production-ready), `develop` (integration branch)
+- **Development**: Always commit new features/fixes to `develop` branch or appropriate feature branches
+- **Branch prefixes**:
+  - `feat/feature-name` - New features, merge to `develop` when complete
+  - `bug/bug-name` - Bug fixes (non-urgent), merge to `develop` when complete
+  - `rel/version` - Release preparation branches, merge to `stable` and then **also** merge `stable` back to `develop`
+  - `hot/version` - Hotfixes for production issues follow same merge rules as releases
+- **Version tags**: Prefix all version tags with `v` (e.g., `v1.0.2`, `v0.0.6`)
+- **Releases**: Update CHANGELOG.md with a summary of changes for each new version
+- **Never commit directly to** `stable` branch (only merge from `rel/` or `hot/` branches)
+- After merging to `stable`, always merge it back to `develop`
+- **Before starting work**: Ensure you're on `develop` branch or create an appropriate feature branch from it

Taskfile.yml

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+version: '3'
+
+tasks:
+  default:
+    cmds:
+      - task: fmt
+      - task: test
+      - task: lint
+
+  fmt:
+    desc: Format go code
+    sources:
+      - '**/*.go'
+    cmds:
+      - go fmt ./...
+      - go mod tidy
+
+  lint:
+    desc: Do static analysis
+    sources:
+      - '**/*.go'
+    cmds:
+      - golangci-lint run
+
+  test:
+    desc: Run unit tests
+    deps: [fmt]
+    sources:
+      - '**/*.go'
+    generates:
+      - build/cover.out
+    cmds:
+      - go test -race -cover -coverprofile build/cover.out ./...
+
+  coverage-report:
+    desc: Build coverage report
+    deps: [test]
+    sources:
+      - build/cover.out
+    generates:
+      - build/cover.html
+    cmds:
+      - go tool cover -html=build/cover.out -o build/cover.html
+
+  serve-report:
+    desc: Serve the coverage report
+    deps: [coverage-report]
+    cmds:
+      - ip addr list | grep inet
+      - python3 -m http.server -d build 3434
+
+  serve-docs:
+    desc: Serve the current docs
+    cmds:
+      - godoc -http=0.0.0.0:3434 -play

go.mod

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+module codeberg.org/danjones000/waiterr
+
+go 1.24.9
+
+require github.com/nalgeon/be v0.3.0

go.sum

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+github.com/nalgeon/be v0.3.0 h1:QsPANqEtcOD5qT2S3KAtIkDBBn8SXUf/Lb5Bi/z4UqM=
+github.com/nalgeon/be v0.3.0/go.mod h1:PMwMuBLopwKJkSHnr2qHyLcZYUTqNejN7A8RAqNWO3E=

waiterr.go

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+package waiterr
+
+import (
+	"errors"
+	"sync"
+)
+
+// WaitErr wraps a sync.WaitGroup with error handling.
+type WaitErr struct {
+	wg   sync.WaitGroup
+	errs []error
+	mut  sync.RWMutex
+}
+
+// Go runs f in its own goroutine. When f returns, its error is stored, and returned
+// with we.Wait()
+func (we *WaitErr) Go(f func() error) {
+	wrap := func() {
+		err := f()
+		we.mut.Lock()
+		defer we.mut.Unlock()
+		we.errs = append(we.errs, err)
+	}
+	we.wg.Go(wrap)
+}
+
+// WaitForError waits for the first error to be returned by one of our go routines, and immediately returns
+// with that error. If all functions return successfully, a nil is returned.
+func (we *WaitErr) WaitForError() error {
+	// Implement this
+	// If we already have an error, return it immediately without waiting
+	// If no error has yet been returned, wait for the very first error and return it
+	return nil
+}
+
+// Wait for all current goroutines to finish. Return an error that combines all errors returned
+// in the group so far (if any).
+func (we *WaitErr) Wait() error {
+	we.wg.Wait()
+	we.mut.RLock()
+	defer we.mut.RUnlock()
+	return errors.Join(we.errs...)
+}
+
+// Unwrap returns all non-nil errors returned by our functions.
+// If we.errs is empty, or all errors are nil, just return nil.
+func (we *WaitErr) Unwrap() []error {
+	errs := make([]error, 0, len(we.errs))
+	for _, e := range we.errs {
+		if e != nil {
+			errs = append(errs, e)
+		}
+	}
+	if len(errs) == 0 {
+		return nil
+	}
+	return errs
+}

waiterr_test.go

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+package waiterr_test
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/nalgeon/be"
+
+	"codeberg.org/danjones000/waiterr"
+)
+
+func TestGo(t *testing.T) {
+	we := new(waiterr.WaitErr)
+	err := errors.New("uh-oh")
+	var run bool
+	we.Go(func() error {
+		run = true
+		return err
+	})
+
+	be.Err(t, we.Wait(), err)
+	be.True(t, run)
+}
+
+func TestWait(t *testing.T) {
+	we := new(waiterr.WaitErr)
+	er1 := errors.New("uh-oh")
+	er2 := errors.New("oops")
+	we.Go(func() error { return er1 })
+	we.Go(func() error { return nil })
+	we.Go(func() error { return er2 })
+
+	err := we.Wait()
+	be.Err(t, err, er1, er2)
+	if ers, ok := err.(interface{ Unwrap() []error }); ok {
+		all := ers.Unwrap()
+		be.Equal(t, len(all), 2)
+		be.True(t, all[0] == er1 || all[0] == er2)
+		be.True(t, all[1] == er2 || all[1] == er1)
+	} else {
+		t.Fatal("Returned error should have Unwrap method")
+	}
+}
+
+func TestWaitForError(t *testing.T) {
+	we := new(waiterr.WaitErr)
+	er1 := errors.New("uh-oh")
+	er2 := errors.New("oops")
+	we.Go(func() error { return nil })
+	we.Go(func() error { return er1 })
+	we.Go(func() error { return er2 })
+
+	err := we.WaitForError()
+	// Due to how goroutines run, it is possible that either of those return first. This is an acceptable limitation
+	be.True(t, err == er1 || err == er2)
+}
+
+func TestWaitForErrorNoErr(t *testing.T) {
+	we := new(waiterr.WaitErr)
+	we.Go(func() error { return nil })
+	we.Go(func() error { return nil })
+	we.Go(func() error { return nil })
+
+	err := we.WaitForError()
+	be.Err(t, err, nil)
+}