Targets section: one Add, then a target type and Next, then that type's fields (closes #370)

The targets section of the webhook page showed its add form open with every field, a URL included for types that use none. It now lists only its targets until "+ Add" is clicked; "+ Add" shows a choice of target type with Next and Cancel on one row, and Next shows the name and only that type's fields. The database and log types show no URL field and the server stores none for them; the slack form gains its retry field. A refused target brings the page back with the form open on its type, the values entered and the reason, and Cancel empties it. An encoding failure stays a logged 500. Target validation returns its message, so the new-webhook page can reuse it.

Model: opus-5-5

internal/handlers/handlers_test.go

@@ -314,16 +314,12 @@ func TestBuildSlackTargetConfig_AcceptsPublicURL(t *testing.T) {
 
 	t.Cleanup(app.RequireStop)
 
-	req := httptest.NewRequestWithContext(
-		context.Background(), http.MethodPost, "/", nil)
-	w := httptest.NewRecorder()
-
-	cfg, err := h.BuildSlackTargetConfigForTest(
-		w, req, "http://93.184.216.34/services/T00/B00/xxx",
+	cfg, errMsg, err := h.BuildSlackTargetConfigForTest(
+		t.Context(), "http://93.184.216.34/services/T00/B00/xxx",
 	)
 
 	require.NoError(t, err)
-	assert.Equal(t, http.StatusOK, w.Code)
+	assert.Empty(t, errMsg)
 	assert.Contains(t, cfg, "webhookUrl")
 }
 
@@ -337,17 +333,13 @@ func TestBuildSlackTargetConfig_RejectsReservedURL(t *testing.T) {
 
 	t.Cleanup(app.RequireStop)
 
-	req := httptest.NewRequestWithContext(
-		context.Background(), http.MethodPost, "/", nil)
-	w := httptest.NewRecorder()
-
-	cfg, err := h.BuildSlackTargetConfigForTest(
-		w, req, "http://169.254.169.254/latest/meta-data/",
+	cfg, errMsg, err := h.BuildSlackTargetConfigForTest(
+		t.Context(), "http://169.254.169.254/latest/meta-data/",
 	)
 
-	require.Error(t, err)
+	require.NoError(t, err)
+	assert.Contains(t, errMsg, "Invalid target URL")
 	assert.Empty(t, cfg)
-	assert.Equal(t, http.StatusBadRequest, w.Code)
 }
 
 func TestRenderTemplate(t *testing.T) {
@@ -444,29 +436,22 @@ func TestRenderTemplateMidRenderErrorSendsNoPartialBody(t *testing.T) {
 func TestBuildDatabaseTargetConfig_Valid(t *testing.T) {
 	t.Parallel()
 
-	var h *handlers.Handlers
-
-	app := newTestApp(t, &h)
-	app.RequireStart()
-
-	t.Cleanup(app.RequireStop)
-
 	// Empty expiry: the keep-forever default, empty config.
-	w := httptest.NewRecorder()
-	cfg, err := h.BuildDatabaseTargetConfigForTest(w, "")
+	cfg, errMsg, err := handlers.BuildDatabaseTargetConfigForTest("")
 	require.NoError(t, err)
+	assert.Empty(t, errMsg)
 	assert.Empty(t, cfg)
 
 	// Explicit never is stored as config.
-	w = httptest.NewRecorder()
-	cfg, err = h.BuildDatabaseTargetConfigForTest(w, "never")
+	cfg, errMsg, err = handlers.BuildDatabaseTargetConfigForTest("never")
 	require.NoError(t, err)
+	assert.Empty(t, errMsg)
 	assert.JSONEq(t, `{"expiry":"never"}`, cfg)
 
 	// A positive duration is stored as config.
-	w = httptest.NewRecorder()
-	cfg, err = h.BuildDatabaseTargetConfigForTest(w, "720h")
+	cfg, errMsg, err = handlers.BuildDatabaseTargetConfigForTest("720h")
 	require.NoError(t, err)
+	assert.Empty(t, errMsg)
 	assert.JSONEq(t, `{"expiry":"720h"}`, cfg)
 }
 
@@ -475,22 +460,14 @@ func TestBuildDatabaseTargetConfig_RejectsBadExpiry(
 ) {
 	t.Parallel()
 
-	var h *handlers.Handlers
-
-	app := newTestApp(t, &h)
-	app.RequireStart()
-
-	t.Cleanup(app.RequireStop)
-
 	for _, bad := range []string{"nonsense", "7d", "-5h"} {
-		w := httptest.NewRecorder()
-		cfg, err := h.BuildDatabaseTargetConfigForTest(w, bad)
+		cfg, errMsg, err := handlers.BuildDatabaseTargetConfigForTest(bad)
 
-		require.Error(t, err, "expiry %q", bad)
-		assert.Empty(t, cfg)
-		assert.Equal(
-			t, http.StatusBadRequest, w.Code,
-			"expiry %q should be rejected with 400", bad,
+		require.NoError(t, err)
+		assert.Contains(
+			t, errMsg, "Invalid archive expiry",
+			"expiry %q should be refused", bad,
 		)
+		assert.Empty(t, cfg)
 	}
 }