## Day 1 14:00 — Onboarding doc for Aiko's first engine task


## Day 1 15:00 — Onboarding doc for Aiko's first engine task


## Day 1 15:00 — Onboarding doc for Aiko's first engine task
I finally got the sync engine architecture doc out of my head and onto the page. I walked through the Rust crate structure, the Postgres batch queue, and the idempotency guarantees so the next junior doesn't have to reverse-engineer the whole flow. I'm a little worried I missed the edge cases around duplicate HL7 messages, but I think this is a solid starting point. I'm genuinely excited that I can actually explain how the data moves from the legacy system into our store without losing a single patient record. I'm hoping Marcus or Priya can review it to make sure I didn't accidentally document a race condition.

## Day 2 11:30 — Onboarding doc for Aiko's first engine task
I drafted the onboarding doc for T10 to help the next junior engineer understand the sync engine without reverse-engineering it. I focused on the core data flow from HL7/FHIR ingestion through the Postgres staging tables to the reconciliation logic, emphasizing our "boring reliability" principle. I included a section on the idempotency guarantees and the critical retry/backoff mechanism so new hires know exactly where the safety nets are. I asked Marcus and Priya if I should add a diagram of the message queue topology, but for now I kept it text-based to avoid stale diagrams. The doc is ready for review by Dana.

## Day 2 13:30 — Onboarding doc for Aiko's first engine task
I've drafted the onboarding doc for T10 to ensure the next junior engineer doesn't have to reverse-engineer the sync engine. I focused on the Rust core, the Postgres schema, and the HL7/FHIR adapters, emphasizing data integrity over feature velocity. I'm hoping Marcus and Priya can review it to ensure I haven't oversimplified the critical failure modes.

## Day 3 09:30 — Onboarding doc for Aiko's first engine task
I finally finished the onboarding doc for the sync engine and honestly felt a bit of relief when I realized I actually understood the whole flow instead of just guessing. I walked through the three main components—the ingest, the transform, and the commit stages—and made sure to call out the idempotency checks and the dead-letter queue so the next junior doesn't get lost in the weeds. I also added a quick section on how to run the local test suite and where to look when a batch fails. It was a lot of work, but I’m really glad it’s done and that I can show Priya and Marcus how it all fits together.

## Day 5 11:30 — Onboarding doc for Aiko's first engine task
I drafted the onboarding doc for T10 to ensure the next junior engineer understands the sync engine's fault tolerance without reverse-engineering the code. I focused on the idempotency guarantees and the dead-letter queue handling for HL7/FHIR payloads, explicitly noting where the Postgres transaction boundaries sit so data is never silently dropped. I kept the tone practical and avoided over-engineering the explanation, prioritizing the "boring but reliable" philosophy. I'm a bit nervous about whether I missed the edge case around duplicate message IDs, so I plan to ask Priya to review the logic flow before merging.

## Day 5 16:00 — Onboarding doc for Aiko's first engine task
I drafted the onboarding doc for the sync engine, focusing on the batch processing flow and the critical idempotency checks that prevent duplicate patient records. I wanted to make sure the next junior engineer doesn't have to reverse-engineer the state machine, so I documented the Postgres schema assumptions and the Rust ownership model for the sync workers. I also added a section on how to run the local test suite with mock HL7 feeds. I'm a bit nervous that I might have oversimplified the retry logic, so I flagged it for Marcus to review during our next sync.