bi-16 — Analysis

What the capstone actually tests

Not whether you can build an application on your own runtime. Whether you can explain a single state update through eight layers, and construct two variants that differ in which layers run.

The application exists to make that explanation concrete and measurable. It should be small and real: a filtered list, a detail route with async data, one animation. Enough surface to exercise every layer; small enough to instrument honestly.

Required invariants of a complete answer

For setCount(count + 1):

  1. Framework scheduling, priority, and batching — named.
  2. Which components re-render, and why those.
  3. The DOM operations — counted, not described.
  4. What the mutation invalidates, cited against css_properties.json5.
  5. Whether layout runs, for which boxes, and what could force it early.
  6. Whether paint re-records or only a property-tree node changes.
  7. Thread and process at each step, and where the hops are.
  8. When the frame is presented, and what could have made it late.

Then the part that demonstrates mastery rather than recall: two variants of the same visible change — one compositor-only, one running every stage — explained at each of the eight layers.

The eight patterns as the real curriculum

By this point the track has produced eight recurring patterns, each appearing in both strands. That cross-strand recurrence is the evidence that they are properties of the problem rather than of any one codebase — and they, not the Chromium paths, are what survives the next five years.

The classification skill from fw-11 applies to the notebook: essential architecture, production hardening, or accretion, defended with evidence. Being able to say "this is accretion, and here is the CL" is what licenses you to argue for removing complexity in systems you own.

The honest self-assessment

The mastery criteria include producing an upstream-quality Chromium change. If the toolchain blocked that, say so explicitly rather than quietly dropping it — and record what remains. A curriculum that lets you mark yourself complete without the falsifiable step is a curriculum that flatters you.