Add the unauthenticated reachability probe

internal/usecase/smoke_reachability.go

@@ -0,0 +1,77 @@
+package usecase
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/url"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+	"gitea.maximumdirect.net/eric/promptkit/internal/generation"
+	"gitea.maximumdirect.net/eric/promptkit/internal/llm"
+)
+
+type smokeHTTPGetter interface {
+	GetWithEvidence(context.Context, string, int) (*http.Response, llm.HTTPExecutionEvidence, error)
+}
+
+type reachabilityProbe struct {
+	client smokeHTTPGetter
+}
+
+type reachabilityProbeOutcome struct {
+	supported       bool
+	reason          domain.SmokeTestReason
+	initialEndpoint string
+	reachable       *bool
+	evidence        llm.HTTPExecutionEvidence
+	failure         domain.ExecutionFailureKind
+}
+
+func (p reachabilityProbe) run(
+	ctx context.Context,
+	endpoint string,
+	timeoutSeconds int,
+) (reachabilityProbeOutcome, error) {
+	if p.client == nil {
+		return reachabilityProbeOutcome{
+			reason: domain.SmokeTestReasonHTTPDiagnosticsUnavailable,
+		}, nil
+	}
+
+	endpoint, err := endpointWithoutUserInfo(endpoint)
+	if err != nil {
+		return reachabilityProbeOutcome{}, fmt.Errorf("prepare reachability endpoint: %w", err)
+	}
+	result := reachabilityProbeOutcome{supported: true, initialEndpoint: endpoint}
+	response, evidence, requestErr := p.client.GetWithEvidence(ctx, endpoint, timeoutSeconds)
+	if response != nil && response.Body != nil {
+		_ = response.Body.Close()
+	}
+	result.evidence = evidence
+	if evidence.ResponseReceived || response != nil {
+		result.reachable = boolPointer(true)
+		return result, nil
+	}
+	if evidence.DispatchInvoked {
+		result.reachable = boolPointer(false)
+	}
+	if requestErr != nil {
+		result.failure = generation.ClassifyFailure(fmt.Errorf("%w: %w", llm.ErrTransport, requestErr))
+		if !evidence.DispatchInvoked {
+			return result, fmt.Errorf("execute reachability request: %w", requestErr)
+		}
+	}
+	return result, nil
+}
+
+func endpointWithoutUserInfo(endpoint string) (string, error) {
+	parsed, err := url.Parse(endpoint)
+	if err != nil {
+		return "", err
+	}
+	parsed.User = nil
+	return parsed.String(), nil
+}
+
+func boolPointer(value bool) *bool { return &value }