chore: establish local platform baseline

internal/health/checker.go

@@ -0,0 +1,51 @@
+package health
+
+import (
+	"context"
+	"sync"
+	"time"
+)
+
+type CheckFunc func(context.Context) error
+
+type Checker struct {
+	timeout time.Duration
+	checks  map[string]CheckFunc
+}
+
+type Result struct {
+	Status string            `json:"status"`
+	Checks map[string]string `json:"checks"`
+}
+
+func NewChecker(timeout time.Duration, checks map[string]CheckFunc) *Checker {
+	return &Checker{timeout: timeout, checks: checks}
+}
+
+func (c *Checker) Ready(ctx context.Context) Result {
+	result := Result{Status: "ready", Checks: make(map[string]string, len(c.checks))}
+	var mutex sync.Mutex
+	var waitGroup sync.WaitGroup
+
+	for name, check := range c.checks {
+		name, check := name, check
+		waitGroup.Add(1)
+		go func() {
+			defer waitGroup.Done()
+			checkContext, cancel := context.WithTimeout(ctx, c.timeout)
+			defer cancel()
+			status := "up"
+			if err := check(checkContext); err != nil {
+				status = "down"
+			}
+			mutex.Lock()
+			result.Checks[name] = status
+			if status == "down" {
+				result.Status = "not_ready"
+			}
+			mutex.Unlock()
+		}()
+	}
+	waitGroup.Wait()
+	return result
+}

internal/health/checker_test.go

@@ -0,0 +1,22 @@
+package health
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+)
+
+func TestReadyReportsDependencyFailure(t *testing.T) {
+	checker := NewChecker(time.Second, map[string]CheckFunc{
+		"database": func(context.Context) error { return nil },
+		"redis":    func(context.Context) error { return errors.New("unavailable") },
+	})
+	result := checker.Ready(context.Background())
+	if result.Status != "not_ready" {
+		t.Fatalf("status = %s, want not_ready", result.Status)
+	}
+	if result.Checks["database"] != "up" || result.Checks["redis"] != "down" {
+		t.Fatalf("unexpected checks: %#v", result.Checks)
+	}
+}