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merged 4 commits into from
May 12, 2025
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Update randomness doc #1281

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randomness doc
tarakby May 12, 2025
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Update docs/tools/kit/index.md
briandoyle81 May 12, 2025
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Update docs/tools/kit/index.md
briandoyle81 May 12, 2025
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Update docs/tools/kit/index.md
tarakby May 12, 2025
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11 changes: 6 additions & 5 deletions docs/tools/kit/index.md
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Expand Up @@ -377,11 +377,12 @@ function RandomValues() {

#### Notes:

* Randomness is generated using Flow’s **on-chain `revertibleRandom`**, producing pseudorandom values tied to block and transaction execution.
* The value returned for identical calls within the same block will be identical.
* This hook is designed for simple use cases that **don’t require a [commit-reveal scheme]**, such as randomized UIs.
* For **more advanced use cases** that **do** require a [commit-reveal scheme], Flow provides built-in support for that pattern.
* Values are **deterministic**: if a transaction fails and retries, the same random value will be regenerated.
* Randomness is generated using Flow’s **on-chain `revertibleRandom`**, producing pseudorandom values tied to block and script execution.
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there are no transactions in this case, it's all script based (under the hood, this makes a difference in how randomness works).

* Values are **deterministic**: The values returned for identical calls within the same block will be identical.
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What is described here in determinism, so I moved the "deterministic" note here

* If `count ` is larger than one, the returned values are disctinct.
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added this so that developers don't think determinism means all count values are equal

* This hook is designed for simple use cases that don't require unpredictability, such as randomized UIs.
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commit-reveal solves the reversibility issue, but here in the script nothing is reversible so commit-reveal doesn't add any advantage.

The main thing developers should be aware of is that the block random source in the lib is publicly known (since this is script-based). There is nothing wrong with that in many applications like the example mentioned here (UIs)

Since the hook uses script executions on existing blocks, Flow's randon source is already public and the randoms are predictable.
* For **more advanced use cases** that **do** require on-chain randomness logic via transactions, Flow provides built-in support using Cadence's `revertibleRandom` and [commit-reveal scheme].
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The more advanced cases are the ones with the logic fully on-chain via transactions (not scripts). This is where randomness is unpredictable, and reversibility can or cannot be an issue, so I added the mention of transactions here. Both "reversibleRandom" and "commit-reveal" work in that case depending on the app.


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