fix: Auto mode is no longer disabled by explictly adding a menu.

A can of worms has been opened.

TODOS.md

@@ -20,6 +20,9 @@
 - [ ] instead of `warnings: [dynamic]Error` we should use `warnings: [dynamic; 8]Error`
   - when limit reached, the template fails and stops rendering.
 - [ ] Brainstorm plugin/tool/(postccs/less/tailwind/sass) support.
+- [ ] Reconsider `"menus": {}` opt-out: it currently discards all page frontmatter
+      menus (with only a warning). Decide whether empty config should instead just
+      suppress the auto-generated menu while still honoring frontmatter.
 
 ## General
 

menus.odin

@@ -4,7 +4,6 @@ import "core:encoding/json"
 import "core:fmt"
 import "core:log"
 import "core:mem"
-import "core:os"
 import "core:strings"
 
 DEFAULT_WEIGHT :: 10
@@ -112,42 +111,32 @@ parse_page_menus :: proc(
 	return result
 }
 
-// build_menus populates site.menus:
+// build_menus populates site.menus by merging every source into one menu set:
-//   1. Config menus (thor.json "menus" key present) — exclusive, preserves array order
+//   1. Auto-menus (sections + root-level pages)
-//   2. Auto-menus (sections + root-level pages) + page frontmatter menus — merged, sorted
+//   2. Config menus (thor.json "menus" key), already parsed into site.menus
+//   3. Page frontmatter menus
+// All three are combined per menu name and sorted by weight, then name.
 //
-// If "menus" is present but empty ({}) it means explicit opt-out: no menus.
+// If "menus" is present but empty ({}) it means explicit opt-out: no menus at
-// Config menus cannot be mixed with page frontmatter menus (error).
+// all, and page frontmatter menus are ignored.
 build_menus :: proc(site: ^Site) {
-	if site.menus != nil {
+	// Explicit opt-out: "menus": {} present but empty → no menus; page
-		has_menus := false
+	// frontmatter menus are ignored (with a warning).
+	// TODO(TODOS.md): silently discarding frontmatter here is harsh; revisit.
+	if site.menus != nil && len(site.menus) == 0 {
 		for page in site.pages {
 			if len(page.menus) > 0 {
-				has_menus = true
-				break
-			}
-		}
-
-		// Already populated from config in site_apply_config
-		if len(site.menus) == 0 {
-			// Explicit opt-out ("menus": {})
-			if has_menus {
 				log.warnf(
 					"menus: config has empty menus but pages have frontmatter menu entries; ignoring page menus",
 				)
+				break
 			}
-			return
 		}
-		// Config menus active
-		if has_menus {
-			log.fatalf("menus: cannot mix config menus with frontmatter menus")
-			os.exit(1)
-		}
-		warn_all_duplicate_weights(site)
 		return
 	}
 
-	// No config menus — auto-generate, then merge page menus on top
+	// Merge all sources: auto section/root menus, config menus (already in
+	// site.menus if present), then page frontmatter menus.
 	collect_auto_menus(site)
 	merge_page_menus(site)
 	warn_all_duplicate_weights(site)
@@ -253,8 +242,17 @@ collect_auto_menus :: proc(site: ^Site) {
 		return
 	}
 
-	sort_menu_entries(entries[:])
+	if site.menus == nil {
 		site.menus = make(map[string][]Menu_Entry, alloc)
+	}
+	// Merge into any existing "main" (e.g. config menus) rather than clobbering.
+	if existing, ok := site.menus["main"]; ok {
+		merged := make([dynamic]Menu_Entry, 0, len(existing) + len(entries), alloc)
+		append(&merged, ..existing)
+		append(&merged, ..entries[:])
+		entries = merged
+	}
+	sort_menu_entries(entries[:])
 	site.menus["main"] = entries[:]
 }
 

menus_test.odin

@@ -421,6 +421,71 @@ test_auto_menus_no_duplicate_with_frontmatter :: proc(t: ^testing.T) {
 	testing.expect_value(t, main[0].name, "Ideas")
 }
 
+// --- config + frontmatter + auto merge tests ---
+
+@(test)
+test_build_menus_config_merges_frontmatter :: proc(t: ^testing.T) {
+	site: Site
+	mem.dynamic_arena_init(&site.arena)
+	defer mem.dynamic_arena_destroy(&site.arena)
+	context.allocator = site_allocator(&site)
+
+	// Simulate config menus as site_apply_config would populate them.
+	site.menus = make(map[string][]Menu_Entry, site_allocator(&site))
+	cfg := make([dynamic]Menu_Entry, 0, 1, site_allocator(&site))
+	append(&cfg, Menu_Entry{name = "GitHub", url = "https://example.com", weight = 20})
+	site.menus["main"] = cfg[:]
+
+	// A root-level page opting into "main" via frontmatter.
+	page := make_page("Ideas", "/ideas/")
+	page.menus = parse_page_menus(parse_raw(`"main"`), page, site_allocator(&site))
+
+	site.pages = make(#soa[dynamic]Page, 0, 1, site_allocator(&site))
+	append(&site.pages, page)
+
+	build_menus(&site)
+
+	main, ok := site.menus["main"]
+	testing.expect(t, ok)
+	// GitHub (config, weight 20) + Ideas (frontmatter, nil → DEFAULT_WEIGHT 10).
+	testing.expect(t, len(main) == 2, "expected config + frontmatter merged")
+	testing.expect_value(t, main[0].name, "Ideas")
+	testing.expect_value(t, main[1].name, "GitHub")
+}
+
+@(test)
+test_build_menus_config_merges_auto :: proc(t: ^testing.T) {
+	site: Site
+	mem.dynamic_arena_init(&site.arena)
+	defer mem.dynamic_arena_destroy(&site.arena)
+	context.allocator = site_allocator(&site)
+
+	// Config menu in a different bucket ("footer"); auto-gen owns "main".
+	site.menus = make(map[string][]Menu_Entry, site_allocator(&site))
+	cfg := make([dynamic]Menu_Entry, 0, 1, site_allocator(&site))
+	append(&cfg, Menu_Entry{name = "GitHub", url = "https://example.com", weight = 20})
+	site.menus["footer"] = cfg[:]
+
+	// A section (non-index) page triggers an auto "main" section entry.
+	page := make_page("Post", "/blog/post/")
+	page.section = "blog"
+
+	site.pages = make(#soa[dynamic]Page, 0, 1, site_allocator(&site))
+	append(&site.pages, page)
+
+	build_menus(&site)
+
+	footer, ok_f := site.menus["footer"]
+	testing.expect(t, ok_f, "config footer menu should be preserved")
+	testing.expect(t, len(footer) == 1)
+	testing.expect_value(t, footer[0].name, "GitHub")
+
+	main, ok_m := site.menus["main"]
+	testing.expect(t, ok_m, "auto-generated main menu should exist alongside config")
+	testing.expect(t, len(main) == 1)
+	testing.expect_value(t, main[0].name, "Blog")
+}
+
 // --- warn_duplicate_weights tests ---
 
 @(test)

site/thor.json

@@ -6,9 +6,21 @@
   "markdown_extensions": {
     "footnotes": true
   },
+  "menus": {
+    "main": [
+      {
+        "name": "GitHub",
+        "url": "https://github.com/sbrow/thor",
+        "weight": 20
+      }
+    ]
+  },
   "params": {
     "author": {
       "name": "Spencer Brower"
-    }
+    },
+    "stylesheets": [
+      "https://cdn.jsdelivr.net/npm/@picocss/pico@2/css/pico.blue.min.css"
+    ]
   }
 }