Let an entrypoint's description be edited in place (closes #392)

Each entrypoint on the webhook page has an Edit button that shows its
description as a form, with Save and Cancel, in place. Edit hides while
the form is open, and going back to the page does not put unsaved text
back into it, so the form always opens on the saved description.
Saving posts to /hook/{id}/entrypoints/{entrypointID}/edit, behind the
same login, CSRF and ownership checks as activate, deactivate and
delete, and writes only the description column, so the URL never
changes. An empty description shows as "Entrypoint". Activate and
deactivate now write only the active column, so they cannot write back
an older description over an edit.

Model: opus-5-5

internal/server/alpine_browser_test.go

@@ -86,6 +86,7 @@ func TestAlpineRunsUnderTheSecurityPolicy(t *testing.T) {
 	checkAddForms(ctx, t, page)
 	checkTargetType(ctx, t, page+"/events")
 	checkCopy(ctx, t, page)
+	checkEntrypointEdit(ctx, t, page, page+"/events")
 	checkEventLog(ctx, t, page+"/events", event.ID, target.Name)
 	checkMobileMenu(ctx, t, page)
 
@@ -363,6 +364,89 @@ func checkCopy(ctx context.Context, t *testing.T, url string) {
 		`clicking Copy does not show "Copied"`)
 }
 
+// checkEntrypointEdit loads a webhook page whose entrypoint has no
+// description, and checks that Edit shows the edit form in place of
+// the description and hides until the form closes, so the form always
+// opens on the saved description; that Cancel hides it and drops what
+// was typed; that after typing, opening the page at elsewhere and going
+// back, Edit again opens the form on the saved description; and that
+// Save changes the description the page shows.
+func checkEntrypointEdit(
+	ctx context.Context, t *testing.T, url, elsewhere string,
+) {
+	t.Helper()
+
+	const (
+		editForm    = `form[action$="/edit"]`
+		input       = editForm + ` input[name="description"]`
+		description = `//span[text()="Entrypoint"]`
+		edit        = `//button[text()="Edit"]`
+	)
+
+	require.NoError(t, chromedp.Run(ctx, loadPage(url)))
+
+	assert.True(t, hidden(ctx, editForm),
+		"the edit form shows before Edit is clicked")
+
+	click(ctx, t, edit)
+	assert.True(t, shown(ctx, editForm),
+		"clicking Edit does not show the edit form")
+	assert.True(t, hidden(ctx, description),
+		"the description stays shown beside the edit form")
+	assert.True(t, hidden(ctx, edit),
+		"Edit stays shown while the edit form is open")
+
+	require.NoError(t, chromedp.Run(
+		ctx, chromedp.SendKeys(input, "draft", chromedp.ByQuery),
+	))
+	click(ctx, t, `//button[text()="Cancel"]`)
+	assert.True(t, hidden(ctx, editForm),
+		"clicking Cancel does not hide the edit form")
+	assert.True(t, shown(ctx, description),
+		"clicking Cancel does not show the description again")
+	assert.True(t, shown(ctx, edit),
+		"clicking Cancel does not show Edit again")
+
+	var typed string
+
+	click(ctx, t, edit)
+	require.NoError(t, chromedp.Run(
+		ctx, chromedp.Value(input, &typed, chromedp.ByQuery),
+	))
+	assert.Empty(t, typed, "Cancel keeps what was typed")
+
+	var loaded string
+
+	require.NoError(t, chromedp.Run(
+		ctx,
+		chromedp.SendKeys(input, "draft", chromedp.ByQuery),
+		loadPage(elsewhere),
+		chromedp.NavigateBack(),
+		chromedp.WaitNotPresent("[x-cloak]", chromedp.ByQuery),
+		chromedp.Evaluate(
+			`performance.getEntriesByType("navigation")[0].type`, &loaded,
+		),
+	))
+	require.Equal(
+		t, "back_forward", loaded,
+		"going back, the browser did not load the page again",
+	)
+
+	click(ctx, t, edit)
+	require.NoError(t, chromedp.Run(
+		ctx, chromedp.Value(input, &typed, chromedp.ByQuery),
+	))
+	assert.Empty(t, typed, "going back puts what was typed back in the form")
+
+	require.NoError(t, chromedp.Run(
+		ctx, chromedp.SendKeys(input, "Billing sender", chromedp.ByQuery),
+	))
+	click(ctx, t, `//button[text()="Save"]`)
+
+	assert.True(t, shown(ctx, `//span[text()="Billing sender"]`),
+		"saving the edit form does not change the description")
+}
+
 // checkEventLog loads the event log and checks that clicking an event's
 // row expands it, that in there clicking its delivery shows the
 // delivery's attempts and clicking again hides them, and that clicking