diff --git a/.github/workflows/website-checks.yml b/.github/workflows/website-checks.yml
index 9549b569a1..bee1081815 100644
--- a/.github/workflows/website-checks.yml
+++ b/.github/workflows/website-checks.yml
@@ -389,7 +389,7 @@ jobs:
       # and /ru/learn/<id>/, and every course a landing at its share path; the
       # check refuses a page, card or learn/sitemap.xml that lags the specs.
       - name: Course
-        run: npm run check:course && npm run test:course && npm run check:course-pages
+        run: npm run check:course && npm run test:course && npm run check:course-pages && npm run check:course-recipe
 
       # The IGLA board on WARS: specs/queen/igla_board.t27 is generated in
       # gHashTag/igla-coder-gpu from committed artifacts. The gate recompiles it,
diff --git a/apps/website/package.json b/apps/website/package.json
index 50cc30d175..6bb4ff033f 100644
--- a/apps/website/package.json
+++ b/apps/website/package.json
@@ -123,6 +123,7 @@
     "check:course": "node scripts/course-from-spec.mjs --check",
     "test:course": "node --test scripts/course-from-spec.test.mjs",
     "gen:course-pages": "node scripts/course-pages.mjs",
+    "check:course-recipe": "node scripts/check-course-recipe.mjs",
     "check:course-pages": "node scripts/course-pages.mjs --check && node --test scripts/course-pages.test.mjs",
     "check:widget-pages": "node scripts/widget-pages-from-spec.mjs --check",
     "test:widget-pages": "node --test scripts/widget-pages-from-spec.test.mjs",
diff --git a/apps/website/scripts/check-course-recipe.mjs b/apps/website/scripts/check-course-recipe.mjs
new file mode 100644
index 0000000000..46f071006a
--- /dev/null
+++ b/apps/website/scripts/check-course-recipe.mjs
@@ -0,0 +1,30 @@
+// Compile every specs/course_recipe/*.t27 with the site's wasm compiler and run its test blocks.
+// Exit 1 on a compile error, a failing assert, a file with zero tests, or an empty directory,
+// so a recipe step cannot be dropped silently. Run from apps/website: npm run check:course-recipe
+import fs from 'node:fs'
+import path from 'node:path'
+import { fileURLToPath } from 'node:url'
+import { loadCompiler, verdictOf, constsOf } from './agents-from-specs.mjs'
+import { runSpecTests } from './viewport-from-spec.mjs'
+
+const site = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..')
+const dir = path.resolve(site, process.argv[2] ?? '../../specs/course_recipe')
+const files = fs.readdirSync(dir).filter((f) => f.endsWith('.t27')).sort()
+if (!files.length) {
+  console.error(`check:course-recipe: no .t27 files in ${dir}`)
+  process.exit(1)
+}
+const analyze = await loadCompiler(fs.readFileSync(path.join(site, 'public/t27/t27_compiler.wasm')))
+let bad = 0
+for (const f of files) {
+  const a = analyze(fs.readFileSync(path.join(dir, f), 'utf8'))
+  const v = verdictOf(a)
+  const env = Object.fromEntries(Object.entries(constsOf(a)).map(([k, c]) => [k, c.value]))
+  const r = runSpecTests(a, env)
+  const ok = v.typecheckOk && !v.errors && !v.discarded && v.hirOk && r.tests > 0 && !r.failures.length
+  if (!ok) bad++
+  console.log(`${ok ? 'ok  ' : 'FAIL'} ${f} module ${a.ast?.name} tests ${r.tests} asserts ${r.asserts} ${JSON.stringify(v)}`)
+  if (!r.tests) console.log('  no tests')
+  for (const x of r.failures) console.log('  fail:', typeof x === 'string' ? x : JSON.stringify(x))
+}
+process.exit(bad ? 1 : 0)
diff --git a/apps/website/src/data/blog/bodies/a-recipe-step-cannot-be-dropped-silently.ts b/apps/website/src/data/blog/bodies/a-recipe-step-cannot-be-dropped-silently.ts
new file mode 100644
index 0000000000..d4505b30c3
--- /dev/null
+++ b/apps/website/src/data/blog/bodies/a-recipe-step-cannot-be-dropped-silently.ts
@@ -0,0 +1,19 @@
+import type { Block } from '../types'
+
+export const body: Block[] = [
+  { "kind": "h", "text": "What changed" },
+  { "kind": "p", "text": "The course recipe in specs/course_recipe had tests, but nothing ran them, so a step could be deleted and nobody would notice. The Course job of the website checks now runs npm run check:course-recipe, which compiles every .t27 file in that directory with the site's own wasm compiler and runs its test blocks." },
+  { "kind": "h", "text": "What makes it fail" },
+  { "kind": "p", "text": "A compile error, a failing assert, a file with zero tests, or an empty directory. To prove it, a mutant changed an asserted constant in roadmap.t27: the check went red with exit code 1, and after the file was restored it went green again." },
+  { "kind": "h", "text": "Limits" },
+  { "kind": "p", "text": "The check runs the tests the modules already have. It does not judge whether those tests cover every step of the recipe." }
+]
+
+export const ruBody: Block[] = [
+  { "kind": "h", "text": "Что изменилось" },
+  { "kind": "p", "text": "У рецепта курса в specs/course_recipe были тесты, но их никто не запускал, так что шаг можно было удалить незаметно. Теперь задание Course в проверках сайта запускает npm run check:course-recipe: он собирает каждый файл .t27 в этой папке wasm-компилятором самого сайта и прогоняет его тесты." },
+  { "kind": "h", "text": "Когда проверка падает" },
+  { "kind": "p", "text": "Ошибка сборки, проваленный assert, файл без тестов или пустая папка. Для доказательства мутант поменял проверяемую константу в roadmap.t27: проверка покраснела с кодом 1, а после восстановления файла снова позеленела." },
+  { "kind": "h", "text": "Ограничения" },
+  { "kind": "p", "text": "Проверка гоняет те тесты, что уже есть в модулях. Покрывают ли они каждый шаг рецепта, она не судит." }
+]
diff --git a/apps/website/src/data/blog/index.ts b/apps/website/src/data/blog/index.ts
index a9b0f87569..303b971564 100644
--- a/apps/website/src/data/blog/index.ts
+++ b/apps/website/src/data/blog/index.ts
@@ -31,6 +31,29 @@ export const postsIndex: PostMeta[] = [
       ],
     },
   },
+  {
+    slug: "a-recipe-step-cannot-be-dropped-silently",
+    title: "A recipe step cannot be dropped silently",
+    summary: "[a CI gate, not new lessons] The website checks now compile and run the tests of the t27 course recipe, and fail on a compile error, a failing assert or a module with no tests.",
+    date: "2026-10-07",
+    readingMinutes: 1,
+    tags: ["t27", "Course", "CI"],
+    receipts: [
+      { label: "The gate, apps/website/scripts/check-course-recipe.mjs", href: "https://github.com/gHashTag/trinity/blob/main/apps/website/scripts/check-course-recipe.mjs" },
+      { label: "The recipe, specs/course_recipe/course-27.t27", href: "https://github.com/gHashTag/trinity/blob/main/specs/course_recipe/course-27.t27" },
+    ],
+    openQuestions: [
+      "Whether the recipe's tests cover every step is not checked.",
+    ],
+    published: true,
+    ru: {
+      title: "Шаг рецепта больше не пропадёт незаметно",
+      summary: "[проверка CI, а не новые уроки] Проверки сайта теперь собирают и запускают тесты рецепта курса t27 и падают на ошибке сборки, проваленном assert или модуле без тестов.",
+      openQuestions: [
+        "Покрывают ли тесты рецепта каждый шаг, не проверяется.",
+      ],
+    },
+  },
   {
     slug: "clocks-resets-and-cdc",
     title: "Clocks, resets and clock-domain crossings, in 27 lessons",
diff --git a/apps/website/src/data/blog/posts.ts b/apps/website/src/data/blog/posts.ts
index e22ed349ae..f7db18fc67 100644
--- a/apps/website/src/data/blog/posts.ts
+++ b/apps/website/src/data/blog/posts.ts
@@ -4,6 +4,7 @@ import { body as body_course_three_verifying_hardware, ruBody as ruBody_course_t
 import { body as body_course_zero_t27_basics, ruBody as ruBody_course_zero_t27_basics } from './bodies/course-zero-t27-basics'
 import { body as body_tri_test_now_runs_the_tests, ruBody as ruBody_tri_test_now_runs_the_tests } from './bodies/tri-test-now-runs-the-tests'
 import { body as body_two_courses_twenty_seven_lessons_each, ruBody as ruBody_two_courses_twenty_seven_lessons_each } from './bodies/two-courses-twenty-seven-lessons-each'
+import { body as body_a_recipe_step_cannot_be_dropped_silently, ruBody as ruBody_a_recipe_step_cannot_be_dropped_silently } from './bodies/a-recipe-step-cannot-be-dropped-silently'
 import { body as body_the_queen_knows_how_to_build_a_course, ruBody as ruBody_the_queen_knows_how_to_build_a_course } from './bodies/the-queen-knows-how-to-build-a-course'
 import { body as body_a_course_pr_carries_its_post, ruBody as ruBody_a_course_pr_carries_its_post } from './bodies/a-course-pr-carries-its-post'
 import { body as body_one_outlier_twenty_three_zeros, ruBody as ruBody_one_outlier_twenty_three_zeros } from './bodies/one-outlier-twenty-three-zeros'
@@ -111,6 +112,7 @@ const bodies: Record<string, PostBody> = {
   'course-zero-t27-basics': { body: body_course_zero_t27_basics, ruBody: ruBody_course_zero_t27_basics },
   'tri-test-now-runs-the-tests': { body: body_tri_test_now_runs_the_tests, ruBody: ruBody_tri_test_now_runs_the_tests },
   'two-courses-twenty-seven-lessons-each': { body: body_two_courses_twenty_seven_lessons_each, ruBody: ruBody_two_courses_twenty_seven_lessons_each },
+  'a-recipe-step-cannot-be-dropped-silently': { body: body_a_recipe_step_cannot_be_dropped_silently, ruBody: ruBody_a_recipe_step_cannot_be_dropped_silently },
   'the-queen-knows-how-to-build-a-course': { body: body_the_queen_knows_how_to_build_a_course, ruBody: ruBody_the_queen_knows_how_to_build_a_course },
   'a-course-pr-carries-its-post': { body: body_a_course_pr_carries_its_post, ruBody: ruBody_a_course_pr_carries_its_post },
   'one-outlier-twenty-three-zeros': { body: body_one_outlier_twenty_three_zeros, ruBody: ruBody_one_outlier_twenty_three_zeros },