Feel the round trip

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One plot, 300 ms away

Remy builds a test: one garden plot, and a server 300 ms away for the round trip.

There are three ways to plant: wait for the server, predict, and predict on the far plot, where something has changed that the app has not heard about yet.

Try it

Plant three ways

Try all three buttons. Watch when the seed appears, and whether it stays.

Try it in the lesson

Quick check

Which of Remy's three ways showed the seed at once and kept it?

  1. Plant with prediction
  2. Plant and wait
  3. Plant on the far plot
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Plant with prediction

Prediction showed the seed at 0 ms, and the server agreed. Waiting took the full 300 ms, and the far plot was refused.

The seed that vanished

On the far plot, the app guessed and the server said no: another player had dropped a rock there. The server's answer wins, so the seed disappears.

Valve's Source corrects such prediction errors and smooths the correction, so a wrong guess does not snap the screen.

Quick check

Why did the server refuse the far plot?

  1. Another player had just put a rock there, and the app had not heard yet
  2. The app planted too quickly
  3. The server was down
Show the answer

Another player had just put a rock there, and the app had not heard yet

A prediction can only use what the app knows. News of the rock was still on its way.

How often guesses fail

With the same rules on both sides, a guess fails only when another player changed the world in that same moment. In a quiet corner of the garden, almost never.

Tune it

At the busy market, many players plant at once, and seeds often vanish. What helps?

  1. Show a sprouting state until the server confirms, only in busy spots
  2. Stop asking the server
  3. Make every plant wait 2 seconds
Show the answer

Show a sprouting state until the server confirms, only in busy spots

Where guesses often fail, a gentle "sprouting" look sets the right expectation. Everywhere else, prediction stays instant.

On the studio board

The studio adds a decision to the board:

A player's own actions are predicted. The server has the final say, and corrections are smoothed.

Bolt says: Next: server reconciliation.

Fact-checked 12 October 2026