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Practice

Practice speech + drawing, not silent reading.

Mocks: voting, vrm, ingest; SDS webhook (easy), rate-limiter (medium), payment-system / robinhood. Method: Method.

1. Observation drill (10 min, no boxes yet)​

Someone (or you) reads an underspecified prompt.

You only: restate, list actors, verbs/nouns/adjectives, ask 5 questions, write NFRs and “worse: stale vs wrong vs down vs leaked.” Stop. This is the skill they named.

2. Forced-box whiteboard (15–20 min, timer)​

Add components only when a constraint appears. Narrate: “Producer can be late → queue. At-least-once → idempotent consumer. Two pictures of the world → break entity. Write must not double-count → unique constraint + client key.”

3. Full board + EM close (45 min)​

Use the problem folders. Candidate: prompt only. Partner: interviewer page.

  1. Loan voting — highest visibility for the domain loop
  2. Reconciliation — two ledgers
  3. Agent ingest — shorter second mock
  4. SDS fluency: webhook then rate limiter; payment or Robinhood if the prompt might be generic/hard

One deep correctness board until it is automatic; ingest as a short variant; one SDS board if you have time. Do not draw two full systems in one hour.

4. Think-aloud recording​

Phone recording + paper/whiteboard. Listen for dead air, jumping to Kafka, or skipping authz. You should sound like you are discovering the design from constraints.

5. Stakeholder overlay (5 min after every board)​

Excel-by-Friday / “it just syncs” / “make the demo look live.” Spine: outcome → constraint → two hows → risk → team implication → ask for a decision.

Never “engineering says no.” Never “we’ll hardcode it.”

6. Exec translation​

Say CAP, sagas, and SLOs in English once per session: “We can have a live-looking grid this week that can be wrong, or a smaller honest slice in two. I recommend two. If the date is political, we cut scope, not golden source.”

Interview clock (45–60 min)​

Adapted from SDS:

  1. Requirements / decomposition (8–10 min) — you lead; write NFRs on the board
  2. APIs (3–5 min) — readable resources, authz in the contract
  3. High-level design (15 min) — one box at a time
  4. Deep dives (15 min) — 2–3 hard constraints
  5. EM close (3–5 min) — rollout, SLOs, team shape, v1 cut, exec summary

If time dies, drop CDN and object storage; keep golden source and authz.

Prep loop​

WhenWhat
Session ASDS primer + NFRs + idempotency/queues/sagas. Close the laptop and recite verbs/nouns/adjectives + CAP in English
Session BOne correctness board twice (once notes, once blank paper, out loud, 20 min) + EM close
Session CTwo-ledger board from Temelio memory + stakeholder “it just syncs”
Session DShort ingest + hot partition / poison / late feed. Then webhook or rate limiter
Night beforeOpen paragraph; 10-min sketch; two stories; sleep. Do not cram Kafka