글로벌 개발자 영어 표현 사전 2026 - 코드 리뷰, 스탠드업, 1:1, RFC, 포스트모템, PR, 인터뷰까지 실전 가이드

[너무 격식적 - 피할 것]
Dear Sarah,
I hope this message finds you well. I am writing to inquire about...

[자연스러움 - 권장]
Hey Sarah - quick q on the auth refactor.
Got a sec to chat about the rate limiter design?
Mind if I borrow you for 5 min on Zoom?

[비동기 친화적]
No need to reply now — when you have a chance, could you take a look at
the design doc? Linking here: [link]. Heads up that the deadline is Thursday.

# RFC: Migrate Payments Service from Postgres to CockroachDB

## Status
- Draft / In Review / Approved / Implemented / Rejected

## Context
[Why are we considering this change? What's the problem?]

## Goals
- Sub-100ms p99 read latency at 10x current traffic
- Multi-region active-active writes

## Non-Goals
- Migrating other services (Notifications, Auth) in this RFC
- Changing the ORM layer

## Proposed Solution
[The recommended approach]

## Alternatives Considered
1. **Vitess sharded MySQL** - Rejected because [reason]
2. **DynamoDB** - Rejected because [reason]
3. **Stay on Postgres with Citus** - Rejected because [reason]

## Trade-offs
[What are we giving up?]

## Open Questions
- How do we handle the dual-write period?
- What's the rollback plan if migration fails at 50%?

## Success Criteria
- p99 read latency < 100ms at 50K QPS
- Zero data loss during migration
- Rollback completes in < 30 min

## Prior Art
- LINE migration: [link]
- Stripe's CockroachDB blog: [link]

## Out of Scope
- Cost analysis (separate doc)
- Team training plan

# Postmortem: Payments API SEV-2 Outage (2026-05-12)

## Summary
On 2026-05-12 at 14:23 UTC, the Payments API began returning 5xx errors
for ~18% of requests. The incident lasted 47 minutes. ~12K transactions
failed. No data loss occurred.

## Impact
- Customer-facing: 12,432 failed transactions, ~$340K GMV impact
- Internal: Triggered SEV-2 page, 8 engineers paged

## Timeline (all times UTC)
- 14:23 - Error rate alert fires
- 14:25 - On-call ack, declares SEV-2
- 14:31 - IC assigned, comms thread opened
- 14:42 - Root cause identified: schema migration deadlock
- 14:55 - Mitigation: roll back migration
- 15:10 - Error rate returns to baseline
- 15:30 - SEV-2 closed

## Root Cause
A schema migration to add an index on payments.user_id acquired an
exclusive lock that conflicted with normal traffic, causing a cascading
connection pool exhaustion.

## Contributing Factors
1. Migration was run during peak hours (vs maintenance window)
2. Lock acquisition mode was not specified, defaulted to exclusive
3. Connection pool sizing assumed no long-lived locks

## What Went Well
- Detection was fast (2 min from impact start to alert)
- IC handoff was smooth across timezones
- Customer comms went out within 15 min

## What Went Poorly
- Migration runbook didn't flag peak-hours risk
- No pre-flight check for lock conflicts
- Rollback procedure took longer than expected

## Action Items
| AI | Owner | Priority | Due |
| --- | --- | --- | --- |
| Add lock-conflict check to migration tool | @alice | P0 | 2026-05-26 |
| Update runbook to prohibit peak-hours migrations | @bob | P1 | 2026-06-02 |
| Add connection pool monitoring dashboard | @charlie | P1 | 2026-06-09 |

## Lessons Learned
- All schema migrations must use CONCURRENTLY for index creation
- Migrations during peak hours require explicit IC approval

## Summary
Adds support for OAuth2 PKCE flow to the auth service.

## Context
Closes #1234. Required for the mobile app refactor (see RFC-2026-042).

## Changes
- New `/oauth/pkce` endpoint
- Adds `code_challenge` validation
- Migrates existing flow behind a feature flag (default off)

## Behind a flag
Enabled via `oauth_pkce_enabled` Statsig flag. Currently off in prod,
on for staging and dev.

## Testing
- Unit tests: 47 new tests, 100% coverage on new code
- Integration: tested with mobile app dev build
- Load: 5K RPS for 10 min, no regression

## Breaking changes
None. Existing flow remains the default.

## Follow-up
- Mobile app integration: PR #1235 (stacked on this one)
- Documentation: PR #1236
- Sunset of legacy implicit flow: planned for Q3 2026

## Screenshots / Recordings
N/A (backend-only change)

## Checklist
- [x] Unit tests added
- [x] Integration tests passing
- [x] Docs updated
- [x] Feature flagged
- [ ] Mobile app PR reviewed (follow-up)

OOO until 2026-05-26. For urgent issues, ping @alice (backup). PRs will be
reviewed on return; for blockers please add @team-payments as reviewer.
For incidents, page on-call via PagerDuty.

1.  LGTM - 코드 리뷰 통과
2.  nit - 사소한 지적
3.  +1 - 동의함
4.  heads up - 미리 알림
5.  FYI - 참고로
6.  cc - 참조
7.  bump - 다시 올림
8.  no rush - 급하지 않음
9.  parking lot - 별도 논의 주제
10. take it offline - 별도 채널에서 논의
11. circle back - 다시 돌아옴
12. follow up - 후속 조치
13. ping me - 알려줘
14. EOD - End of Day, 오늘 마감
15. EOW - End of Week, 이번 주 마감
16. quick sync - 짧은 회의
17. blocked on - ...에 막힘
18. blast radius - 영향 범위
19. behind a flag - 피처 플래그 뒤
20. root cause - 근본 원인

[협상 시작 — 이메일]
Subject: Offer for Senior Engineer - Compensation Discussion

Hi [Recruiter],

Thank you for the offer for the Senior Engineer role on the Payments team.
I'm genuinely excited about the team and the work.

Before I sign, I'd like to align on compensation. Based on my research
and competing offers, I was hoping we could revisit the base salary
component. Specifically, I'd like to see [number] base, which reflects
my [X] years at [level] and recent market data from levels.fyi for
similar roles at peer companies.

Happy to discuss on a call if helpful. Looking forward to making this work.

Best,
[Name]

[정중한 거절 — 이메일]
Subject: Offer Update

Hi [Recruiter],

Thank you again for the offer and the time the team invested in
interviewing me. After much deliberation, I've decided to accept a
different offer that's a better fit for my current situation.

I have a lot of respect for the team and the work, and I'd love to
stay in touch. Please let me know if there are ways to keep in contact
for future opportunities.

Best,
[Name]