fix: use server-computed endsAt for exploration timer to prevent clock drift #68

2026-03-18T16:47:03-07:00

hikari commented

2026-03-18 16:47:03 -07:00

Summary

Exploration timers showed more time than the area's stated duration when the server clock was ahead of the client's
The timer was derived from startedAt = endsAt - durationMs, then computed as durationSeconds - (clientNow - startedAt) / 1000 — any server/client clock skew directly inflated the result
Now stores endsAt (the server-computed completion timestamp) directly in ExplorationAreaState and computes the timer as (endsAt - Date.now()) / 1000, which is immune to clock drift
Old saves without endsAt fall back gracefully to the previous startedAt-based calculation

Test plan

Start a new exploration — timer should show exactly the area's stated duration (no more "1h area shows 1h15m")
Refresh the page mid-exploration — timer should resume from the correct remaining time (using server-anchored endsAt)
Old saves with startedAt but no endsAt should still display a timer via the fallback path

Closes #53

✨ This PR was created with help from Hikari~ 🌸

## Summary - Exploration timers showed more time than the area's stated duration when the server clock was ahead of the client's - The timer was derived from `startedAt = endsAt - durationMs`, then computed as `durationSeconds - (clientNow - startedAt) / 1000` — any server/client clock skew directly inflated the result - Now stores `endsAt` (the server-computed completion timestamp) directly in `ExplorationAreaState` and computes the timer as `(endsAt - Date.now()) / 1000`, which is immune to clock drift - Old saves without `endsAt` fall back gracefully to the previous `startedAt`-based calculation ## Test plan - [ ] Start a new exploration — timer should show exactly the area's stated duration (no more "1h area shows 1h15m") - [ ] Refresh the page mid-exploration — timer should resume from the correct remaining time (using server-anchored `endsAt`) - [ ] Old saves with `startedAt` but no `endsAt` should still display a timer via the fallback path Closes #53 ✨ This PR was created with help from Hikari~ 🌸

hikari added 1 commit 2026-03-18 16:47:03 -07:00

fix: use server-computed endsAt for exploration timer to prevent clock drift

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53eaebd7d8

Exploration timers were showing more time than the area's stated duration
when the server clock was ahead of the client clock. The timer now uses
the server-provided endsAt timestamp directly instead of deriving startedAt
from it, making countdowns immune to client/server clock skew. Old saves
without endsAt fall back to the previous startedAt-based calculation.

Closes #53

naomi merged commit cfcf763ce3 into main

2026-03-18 17:09:48 -07:00

naomi deleted branch fix/exploration-timer-drift

2026-03-18 17:09:48 -07:00

naomi referenced this issue from a commit

2026-03-18 17:09:49 -07:00

fix: use server-computed endsAt for exploration timer to prevent clock drift (#68)

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Reference: nhcarrigan/elysium#68