Render --help=cookbook from the help model

xff/cli/help.cc

@@ -223,16 +223,6 @@ absl::Span<const Recipe> CookbookRecipes() {
 
 namespace {
 
-std::string RenderCookbook() {
-  std::string out =
-      "xff cookbook: worked examples that compose xff's building blocks. Each shows a task, the\n"
-      "command, and how it works. See --help=fields for {field}s and --help=stats for the reductions.\n";
-  for (const Recipe& recipe : CookbookRecipes()) {
-    absl::StrAppend(&out, "\n  ", recipe.task, "\n    ", recipe.command, "\n    ", recipe.note, "\n");
-  }
-  return out;
-}
-
 // The `--help=licenses` topic: a minimum-viable license summary. xff's own license, the core
 // libraries always linked in, and the build extras with whether THIS binary has them (via
 // ExtraEnabled, so it reflects the actual build). Full notice texts live in the NOTICE file; this
@@ -455,9 +445,6 @@ absl::StatusOr<std::string> RenderHelp(std::string_view topic) {
   if (topic == "expressions") {
     return RenderExpressions();  // the annotated Tests/Actions/Operators list, sans globals
   }
-  if (topic == "cookbook" || topic == "examples" || topic == "recipes") {
-    return RenderCookbook();  // worked examples composing the building blocks end to end
-  }
   if (topic == "notice" || topic == "notices") {
     return RenderNotice();  // third-party component manifest + what this binary contains
   }

xff/cli/help_build.cc

@@ -529,6 +529,8 @@ std::optional<Document> TopicReference(std::string_view name) {
     doc.sections.push_back(StatsSection());
   } else if (name == "config") {
     doc.sections.push_back(ConfigSection());
+  } else if (name == "cookbook" || name == "examples" || name == "recipes") {
+    doc.sections.push_back(BuildExamples());
   } else {
     return std::nullopt;
   }

xff/cli/help_render_test.cc

@@ -173,7 +173,7 @@ TEST_F(HelpTest, EveryAdvertisedTopicRendersAndAliasesAreSynonyms) {
   for (const HelpTopic& topic : HelpTopics()) {
     if (topic.name == "styles" || topic.name == "fields" || topic.name == "printf" || topic.name == "time"
         || topic.name == "size" || topic.name == "grammars" || topic.name == "extras" || topic.name == "stats"
-        || topic.name == "config") {
+        || topic.name == "config" || topic.name == "cookbook") {
       continue;  // rendered from the model (TopicReference) or the CLI facets, not RenderHelp
     }
     const absl::StatusOr<std::string> rendered = RenderHelp(topic.name);

xff/cli/help_topic_test.sh

@@ -138,7 +138,7 @@ test::help_cookbook_lists_worked_examples() {
   # carries a runnable command. It also folds into --help=full.
   local cookbook full
   cookbook="$("$(_xff_bin)" --help=cookbook 2>&1)"
-  expect_output_contains 'xff cookbook' "${cookbook}"
+  expect_output_contains 'Worked examples' "${cookbook}"
   expect_output_contains 'git blame' "${cookbook}"                           # the flagship -exec recipe
   expect_output_contains 'xff . -type f --summary=ext' "${cookbook}"         # a runnable command (global at the tail)
   expect_output_contains 'Ten largest files' "${cookbook}"                   # a recipe task heading