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. The column is NOT NULL and a check constraint refuses a value
below 1, so every target, whatever its type, is stored with at least
1. 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; a blank field on the add target form gives 1, and on the
edit form keeps the stored value. 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"),
 	}