Source of Truth

This project treats source code, tests, and authored notes as durable study material. Generated docs and PDFs must be reproducible from those inputs, and employer-specific interview prep must never enter this tree. This page is the whole contract.

Authored Material

Path	Purpose
src/algo/	Algorithm implementations and docstrings
tests/	Examples and property-based correctness checks
src/concepts/	Technical concept modules
src/practice/	Code-reading and decomposition exercises
reference-sheets/	Printable notes, quick-reference sheets, and the practice method (sheets 10–11)
reference-sheets/appendix-topics.json	Structured appendix topics rendered into the booklet compile-safely

Generated Material

Output	Command
booklet.tex / booklet.pdf / docs/assets/booklet.pdf	just packet
reference-sheets/pdf/*.pdf	just pdf-all
site/	just docs-build

Three Layers

Layer	What	Where	Public?
L1 — knowledge	algorithms, tests, concepts, reference sheets 01–09	this repo	✅
L2 — practice method	sheets 10–11, just interview / just rep, spaced repetition	this repo	✅
L3 — private overlay	employer/panel front & back matter, people, dates, tailored positioning, personal rep logs	a private downstream repo	⛔ never here

The distinction that keeps this publishable:undefinedis a method ("how to stay calm and narrate at a whiteboard" — a general, teachable skill);undefinedis a dossier (who is on Tuesday's panel). Method publishes; dossier never touches this tree. If a sentence only makes sense for one employer, it is L3.

The Graph Edge Is One-Way

private superset repo                    THIS REPO (public)
─────────────────────                    ──────────────────
bazel_dep + path/git override   ──────▶  module(name = "dsa_study_packet")
\includepdf{@dsa_study_packet            //:booklet  (neutral PDF)
            //:booklet}
+ private front/back matter (L3)
→ private //:study_packets

The private repo depends on this one; this repo knows nothing about any downstream. Composition is overlay, not bundle: the neutral booklet is compiled here from this tree (so it cannot contain employer text), and a private lane \includepdfs the finished PDF between its own front and back matter. The two bodies of text only ever meet as adjacent pages in a private output — never in source. Delete the private repo and this SSOT is unchanged and complete. examples/overlay-demo/ is a self-contained, fork-me demonstration of the pattern with placeholder content.

The Boundary Is Enforced

scripts/check_public_boundary.py (just public-boundary) fails if any tracked file contains secret-shaped content or secret-file paths: tracked SOPS or dotenv files, age keys, GitHub tokens, private-key blocks, legacy secret tripwires. Name-specific tripwires (employers, panels, private repo names) are deliberately not listed here — the private downstream repo scans this tree with its own marker list, so the public guard cannot itself disclose what it guards against. Neutrality is a machine check, not a promise. Personal rep scores (.challenges/reps.md) are gitignored by default — publish aggregates deliberately, or not at all.

Who Owns The Practice Method

L2 is one loop described from five angles. Each surface owns exactly one question about it; none restates another's answer.

Surface	Owns	Does not own
Sheet 10	the CLARP method + self-review rubric — how to perform	no calendar, no daily loop
Sheet 11	the 14-day calendar + daily loop — when. Its prose feeds scripts/practice_day.py closely — edit sheet 11 itself for loop changes, never this table	no method detail, no rubric
Evidence page	why — research citations and the video shelf	no calendar, no rubric scoring
AGENTS.md persona	how the resident interviewer behaves during a rep; regenerates the .github surfaces via just gen-agents	no citations, no calendar
Skills (practice-day, interviewer)	routing — which rung, which just command runs next	no method content of its own

A change landing on the wrong row is the drift tell: a calendar edit inside sheet 10, a rubric row inside the evidence page, or a citation inside AGENTS.md all mean the edit belongs one row up or down this table instead.

Runbook

I want to…	Do this	Layer
Add/extend a study or practice sheet	reference-sheets/NN-*.md + one-line docs/reference/NN-*.md wrapper; nav + PDF pick it up	L1/L2
Add an algorithm	src/algo/<topic>/<problem>.py + tests; booklet and site regenerate	L1
Prep for a specific employer/panel	Create a lane in the private downstream repo; author front/back matter there	L3
Keep practice tapes / mock scripts / rep scores	Private repo or gitignored local dir — never tracked here	L3