Store a target's number of delivery attempts, at least one (closes #540)

Target.MaxRetries (max_retries) becomes Target.MaxAttempts
(max_attempts), and the form field, parser and ceiling are renamed to
match. 1 is a single attempt with no circuit breaker; above 1 retries
behind the breaker up to that many attempts. Both target forms refuse
0 and less and default a blank field to 1. The target page shows the
plain number, and the README's two paragraphs on 0 against 1 become
one sentence.

Model: opus-5-5

internal/handlers/target_create.go

@@ -102,9 +102,10 @@ func (h *Handlers) newTarget(
 	in targetFormInput,
 ) (*database.Target, string, error) {
 	target := &database.Target{
-		WebhookID: webhookID,
-		Type:      in.Type,
-		Active:    true,
+		WebhookID:   webhookID,
+		Type:        in.Type,
+		Active:      true,
+		MaxAttempts: 1,
 	}
 
 	errMsg, err := h.setTargetFromForm(ctx, target, in)
@@ -117,9 +118,10 @@ func (h *Handlers) newTarget(
 
 // setTargetFromForm validates a target form against the target's type
 // and, when it accepts it, sets the target's name, configuration and
-// retry count from it. It returns the message the form shows for
-// anything it refuses, an unknown type among them, and then leaves the
-// target unchanged; an error is the server's fault, as for newTarget.
+// number of delivery attempts from it. It returns the message the form
+// shows for anything it refuses, an unknown type among them, and then
+// leaves the target unchanged; an error is the server's fault, as for
+// newTarget.
 // The add target form and the target edit form both go through here,
 // so the two cannot come to disagree about what a target may be.
 func (h *Handlers) setTargetFromForm(
@@ -136,20 +138,20 @@ func (h *Handlers) setTargetFromForm(
 		return errMsg, err
 	}
 
-	// An empty max_retries keeps the target's count: the
-	// fire-and-forget default of 0 for a new target, and the stored
-	// count for an edited one, since the forms for target types that
-	// do not retry have no such field. A value that is filled in but
-	// invalid is refused rather than becoming that count, so a typo
-	// cannot destroy the count a target is delivering with.
-	maxRetries, err := parseMaxRetries(in.MaxRetries, target.MaxRetries)
+	// An empty max_attempts keeps the target's count: the default of
+	// 1 for a new target, and the stored count for an edited one,
+	// since the forms for target types that do not retry have no such
+	// field. A value that is filled in but invalid is refused rather
+	// than becoming that count, so a typo cannot destroy the count a
+	// target is delivering with.
+	maxAttempts, err := parseMaxAttempts(in.MaxAttempts, target.MaxAttempts)
 	if err != nil {
-		return "Invalid delivery attempts: " + retriesErrorMessage(err), nil
+		return "Invalid delivery attempts: " + attemptsErrorMessage(err), nil
 	}
 
 	target.Name = in.Name
 	target.Config = configJSON
-	target.MaxRetries = maxRetries
+	target.MaxAttempts = maxAttempts
 
 	return "", nil
 }
@@ -176,8 +178,8 @@ type targetFormInput struct {
 	// ForwardQuery is an HTTP target's checkbox that passes each
 	// event's query string on to it.
 	ForwardQuery bool
-	// MaxRetries is an HTTP or Slack target's max_retries.
-	MaxRetries string
+	// MaxAttempts is an HTTP or Slack target's max_attempts.
+	MaxAttempts string
 	// Expiry is a database (archive) target's row expiry.
 	Expiry string
 	// Rotation is a database (archive) target's rotation.
@@ -204,7 +206,7 @@ func targetFormInputFrom(r *http.Request) targetFormInput {
 		Headers:      r.PostFormValue("headers"),
 		Timeout:      r.PostFormValue("timeout"),
 		ForwardQuery: r.PostFormValue("forward_query") != "",
-		MaxRetries:   r.PostFormValue("max_retries"),
+		MaxAttempts:  r.PostFormValue("max_attempts"),
 		Expiry:       r.PostFormValue("expiry"),
 		Rotation:     r.PostFormValue("rotation"),
 	}