fix(course): 9 modules of 3 lessons in every course

[gHashTag]

Every t27 course is 9 modules of 3 lessons, 27 lessons in total (owner, 2026-10-07). An earlier change misread this as 27 modules of one lesson and flattened courses 0, 1 and 2. This PR restores 9x3 everywhere the course shape lives.

Changes

• specs/course/courses.t27: MODULES_PER_COURSE = 9, LESSONS_PER_MODULE = 3, asserted in every_course_is_three_cubed.
• t27-basics.t27, course.t27, ai-numbers.t27 and their RU bundles: 9 module titles each, LESSON_MODULES regrouped 3 per module. Course 1 returns to its earlier 9x3 grouping; course 0's grouping is new and has not been reviewed by the owner.
• scripts/course-from-spec.mjs + test: checks each course's shape against the catalog.
• src/pages/Course.css: module headers with three lessons under each.
• Regenerated course.generated.ts, public/learn/* pages and cards.
• Blog post nine-modules-of-three-again (English body, Russian ruBody).

Proof

• All generators rc 0; gates check:widgets, test:widgets-spec, check:widget-pages, check:course, test:course, check:course-pages, check:onboarding, check:play, check:subpath-urls, tsc --noEmit rc 0.
• Mutant: MODULES_PER_COURSE 9 -> 27 makes check:course exit 1 (every_course_is_three_cubed asserts ci: Bump actions/setup-node from 4 to 6 #2, ci: Bump actions/setup-python from 5 to 6 #3 false); git checkout -- restores rc 0.

Base is feat/course-t27-basics-0 (trinity#1463) because course 0 is not on main yet. Course 3 (#1470) carries the same courses.t27 values and turns green once this lands.

{
  "version": 1,
  "head_sha": "6e6efd25ddaf8c56f5aa9df432923c06c67a03b5",
  "summary": "Every t27 course goes back to 9 modules of 3 lessons, the owner's shape, after an earlier change flattened courses 0 to 2 into 27 modules of one lesson.",
  "changes": [
    "specs/course/courses.t27: MODULES_PER_COURSE 9 and LESSONS_PER_MODULE 3, asserted by every_course_is_three_cubed",
    "specs/course t27-basics, course and ai-numbers with their RU bundles: nine module titles each, three lessons per module",
    "scripts/course-from-spec.mjs and its test: every course's shape is checked against the catalog values",
    "src/pages/Course.css plus regenerated course.generated.ts, learn pages and cards; blog post nine-modules-of-three-again"
  ],
  "tests": [
    {
      "command": "npm run check:course, test:course, check:course-pages, check:widgets, test:widgets-spec, check:widget-pages, check:onboarding, check:play, check:subpath-urls; npx tsc --noEmit",
      "result": "all rc 0, exit code 0 with no error output",
      "status": "passed",
      "evidence": "local run on 6e6efd25"
    },
    {
      "command": "mutant MODULES_PER_COURSE 9 to 27 then npm run check:course",
      "result": "rc 1, every_course_is_three_cubed asserts 2 and 3 false; restored rc 0",
      "status": "passed",
      "evidence": "local run on 6e6efd25"
    }
  ],
  "limitations": [
    "Course 0's nine modules are a new grouping and have not been reviewed by the owner",
    "Base is feat/course-t27-basics-0, so this lands only after trinity#1463 or with it",
    "Course 3 GoldenFloat (trinity#1470) repeats the catalog values and needs this merged first"
  ],
  "tags": [
    "t27",
    "course"
  ],
  "blog": {
    "title": "Nine modules of three lessons, again",
    "summary": "Every t27 course is back to nine modules of three lessons after a misread flattened them.",
    "outline": [
      "The owner's shape for a t27 course is nine modules of three lessons, twenty-seven lessons, and an earlier change misread it as twenty-seven modules.",
      "That change flattened courses 0, 1 and 2, so a reader saw one long list of lessons instead of nine steps with three lessons each.",
      "The catalog now asserts nine and three, and the generator refuses any course whose shape differs, which a planted 27 proved red.",
      "Course 0's new grouping is still waiting for the owner's review, and course 3 joins the same shape once this lands."
    ]
  }
}

🤖 Generated with Claude Code