Phases & Modules

This repository holds three parallel tracks, all sharing the same module shape:

They are siblings, not stages. The frontend track develops judgment; the internals tracks remove abstraction boundaries. Cross between them when a topic genuinely stalls without the other — the hooks are enumerated in the Curriculum Map §2.

The phase structure below applies to the frontend track. The bi- and fw- tracks are ordered but not phased; see their own roadmap modules (bi-00, fw-01).

Seven phases, 51 modules, plus a continuous AI-assisted-engineering spine. The ordering is derived from real dependencies, not topic popularity — see the Curriculum Map for the dependency graph and the five load-bearing chains.

Legend: ✅ built & measured · 🟡 scaffolded · ⬜ planned

Phase 1 — Platform Substrate · Foundation → Senior

Before any abstraction, know what the abstraction is hiding.

Gate 1 → 2: predict execution order and rendering timing of unfamiliar async code unaided · find a leak from a heap-snapshot diff · read a waterfall and name the bottleneck class.

Phase 2 — Framework Mechanics · Senior

A framework is a scheduling and diffing policy with ergonomics attached.

Phase 3 — Architecture & Data · Senior → Staff

A frontend is a distributed system with a rendering engine attached.

Phase 4 — Quality Attributes · Staff

These are properties of the architecture, and they are measurable.

Phase 5 — Quality Engineering · Staff

Thousands of tests can still produce low confidence.

Phase 6 — Platform & Delivery · Staff → Principal

You stop building applications and start building the conditions under which others build them.

Phase 7 — Principal Judgment · Principal → Distinguished

The work is now decisions, influence, and being right about reversibility.

The spine — AI-assisted engineering

Specification areas §20–24 are not a phase. They run continuously from Phase 1, because deferring them means practising the workflows only after your judgement is good enough not to need practice. The governing rule: an agent may produce anything whose failure modes you can enumerate yourself.

Sibling tracks

Browser Internals (bi-00 … bi-16) — Chromium architecture, the HTML parser, DOM internals, the V8 binding layer, the CSS engine, layout, paint, the compositor, scheduling, tracing, Web Platform Tests, and the contribution workflow. Start at bi-00.

Framework Internals (fw-01 … fw-12) — build a Redux, a React core, a signals runtime, a concurrent scheduler, a Vue renderer, a template compiler, a bundler, a router, a query cache and a virtualised list, then read the production sources. Start at fw-01.

Both live in the sibling project ../browser-framework-internals/, which builds as its own book and deploys separately.