Phase 19 Labs — Capstone: Maintainer & Startup
Two process labs — no starters, no pytest; the graders are the vLLM review queue and your own honesty. Lab-01 turns the course's knowledge into a merged upstream PR: harvest real issues, run the disqualification gauntlet (claimed? reproducible? within your map? testable? reviewable?), and write the one-page implementation plan a maintainer would approve. Lab-02 is the exit exam: a timed four-session mock staff loop (rapid-fire, deep-dive, design, debugging) built from eighteen phases of INTERVIEW.md files, scored against CAREER.md's competency map — peeks cap at 2, skipped arithmetic caps at 2, and the low rows become your revision list.
Exit criteria for the course, per these labs:
1. A merged (or at least review-surviving) upstream PR. [lab-01]
2. A competency matrix you'd show a hiring manager. [lab-02]
Contents
Labs
lab-01-find-and-scope-a-pr [CPU-OK]
Issue triage as engineering: three candidates, five disqualification checks in cost order, and the survivor scoped with the course's move — find the load-bearing lines, name the invariants, plan the regression test, bound the blast radius (TP/quant/LoRA/spec interactions), and write the one-pager with an explicit out-of-scope line. Plus the mechanical friction-removers: claim the issue first, pre-commit hooks, DCO sign-off. Skills: selection and scoping — the actual gap between knowing and contributing.
lab-02-mock-staff-loop [CPU-OK]
Four timed sessions: rapid-fire fundamentals (phases 0–3), systems deep-dive (4–8), a design scenario with topology + knobs + shown arithmetic + named risks (choose from three realistic builds), and two debugging trees from the symptom catalog. Graded in three layers per answer — mechanism, invariant/arithmetic, operational consequence — against the model answers and the competency map. Skills: producing under pressure; committing to defended choices; calibrated self-assessment; the staff sentence ("128 KiB/token, so…").
Where to go from here
The course's final claim was made on page one: finish every lab and you can read
and modify any part of vLLM, operate it like a principal engineer, and know where
the moats are. These two labs are where you check the claim against reality — the
PR against the review queue, the matrix against the map. Whatever rows come back
weak, the phases are still there; whatever comes back strong, CAREER.md
maps the three roads it opens (maintainer, staff IC, founder). Your notebook,
your mini_vllm, your tuning reports, and your merged PR are the portfolio.
Don't Panic — you built the whole engine once already.