Fix draft timer display drifting due to server-client clock skew #74

Merged

chrisp merged 2 commits from fix/timer-clock-skew into main 2026-06-06 07:30:45 +00:00

Conversation 0 Commits 2 Files changed 2 +13 -7

chrisp commented 2026-06-06 07:19:37 +00:00

Owner

Copy link

Summary

• The countdown display used data.expiresAt (server-side Unix timestamp) subtracted from client Date.now(). When the server clock runs ~2-3s ahead of the client (observed in production), the display was inflated by that delta.
• Fixes three linked symptoms: timer starting at 2:02 instead of 2:00, chess-clock increment crediting 1:54 instead of 1:55, and the commissioner's adjust-time-bank dialog disagreeing with the visible countdown.
• Fix: replace all server expiresAt timestamps with a client-local expiry from the server-provided timeRemaining integer (Date.now() + timeRemaining * 1000). The skew then cancels algebraically when the server computes credit.

Sites changed

• handleTimerPickStarted — fires after every pick (the main fix)
• handleDraftStateSync — reconnect path
• useState initializer in the draft room — initial page load seed from loader data (uses loaderTimerNow server timestamp to compute remaining server-side, then re-anchors to client clock)

Test plan

• Start a chess-clock draft (2:00 bank, 15s increment) — timer should show exactly 2:00 when a team goes on the clock
• Pick at 1:40 — new bank should show 1:55 (100 + 15s)
• Commissioner adjust-time-bank dialog — displayed remaining should match the countdown
• Force autopick at any displayed time T — new bank should be T + increment
• Reconnect mid-pick — timer should resume at the correct remaining time

🤖 Generated with Claude Code

## Summary - The countdown display used `data.expiresAt` (server-side Unix timestamp) subtracted from `client Date.now()`. When the server clock runs ~2-3s ahead of the client (observed in production), the display was inflated by that delta. - Fixes three linked symptoms: timer starting at 2:02 instead of 2:00, chess-clock increment crediting 1:54 instead of 1:55, and the commissioner's adjust-time-bank dialog disagreeing with the visible countdown. - Fix: replace all server `expiresAt` timestamps with a client-local expiry from the server-provided `timeRemaining` integer (`Date.now() + timeRemaining * 1000`). The skew then cancels algebraically when the server computes credit. ## Sites changed - `handleTimerPickStarted` — fires after every pick (the main fix) - `handleDraftStateSync` — reconnect path - `useState` initializer in the draft room — initial page load seed from loader data (uses `loaderTimerNow` server timestamp to compute remaining server-side, then re-anchors to client clock) ## Test plan - [ ] Start a chess-clock draft (2:00 bank, 15s increment) — timer should show exactly **2:00** when a team goes on the clock - [ ] Pick at 1:40 — new bank should show **1:55** (100 + 15s) - [ ] Commissioner adjust-time-bank dialog — displayed remaining should match the countdown - [ ] Force autopick at any displayed time T — new bank should be T + increment - [ ] Reconnect mid-pick — timer should resume at the correct remaining time 🤖 Generated with [Claude Code](https://claude.com/claude-code)

chrisp added 1 commit 2026-06-06 07:19:38 +00:00

Fix draft timer display drifting due to server-client clock skew ... a91c108393

The countdown display used data.expiresAt (a server-side Unix timestamp)
subtracted from client Date.now(). When the server clock is ahead of the
client by ~2-3s (observed in production), the display inflated by that
delta — causing 2:02 instead of 2:00 on pick start, short-crediting the
chess clock increment, and the commissioner's adjust-time-bank dialog
disagreeing with the visible countdown.

Fix: replace all server expiresAt timestamps with a client-local expiry
computed from the server-provided timeRemaining integer
(Date.now() + timeRemaining * 1000). The skew then cancels algebraically:
server_remaining = server_expiresAt - pickMadeAt
                 = (client_schedule + Δ + bank*1000) - (client_pick + Δ)
                 = client_expiresAt - client_pick  ✓

Three sites updated: handleTimerPickStarted, handleDraftStateSync
(reconnect), and the initial useState seed from loader data.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

chrisp added 1 commit 2026-06-06 07:25:28 +00:00

Fix TS error: narrow picksExpiresAt via optional chain guard ... a4317815f7

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

chrisp merged commit 079ecec129 into main 2026-06-06 07:30:45 +00:00

chrisp deleted branch fix/timer-clock-skew 2026-06-06 07:30:46 +00:00

chrisp referenced this pull request from a commit 2026-06-06 07:30:47 +00:00

Fix draft timer display drifting due to server-client clock skew (#74)

Sign in to join this conversation.

Reviewers

No reviewers

Labels

Clear labels   

admin

Admin page tooling

  

defect

Something isn't working

  

draft

Related to the draft room

  

feature

New feature or request

  

infrastructure

Related to database/site infrastructure

  

new sport

Issue to add a new sport to the rotation

  

security

Things that can cause security issues

  

tech debt

Cleaning up things that will make us have a better life

  

ux

User interface or marketing

No labels

admin

defect

draft

feature

infrastructure

new sport

security

tech debt

ux

Milestone

Clear milestone

No items

No milestone

Projects

Clear projects

No items

No project

Assignees

Clear assignees

No assignees

1 participant

Notifications

Subscribe

Due date

The due date is invalid or out of range. Please use the format "yyyy-mm-dd".

No due date set.

Dependencies

No dependencies set.

Reference: chrisp/brackt#74

No description provided.