Check F3 (fast finality)

[hugomrdias]

https://www.notion.so/filecoindev/Exchange-and-RPC-providers-guide-to-F3-Fast-Finality-105dc41950c180c49175e4b3afcc5923?source=copy_link#20adc41950c180099b50dda8130e7301

[BigLep]

Thanks for creating this issue @hugomrdias . Agreed that it looks like https://www.notion.so/filecoindev/Exchange-and-RPC-providers-guide-to-F3-Fast-Finality-105dc41950c180c49175e4b3afcc5923=#20adc41950c180099b50dda8130e7301 is the pattern to follow. (Although I'm wondering if that should just be exposed as a first-class /v2 API because I imagine this pattern is going to be very common.)

---

Notes from my own looking...

Safety Levels

1. "finalized" - 900 blocks behind the current head
2. "safe" - 30 blocks behind the current head
3. "latest" - Current head (0 blocks behind)

The finality logic is implemented in the getIDAddress method:

• Type definition: https://github.com/hugomrdias/filecoin/blob/main/packages/iso-filecoin/src/types.ts#L83
• Main implementation: https://github.com/hugomrdias/filecoin/blob/main/packages/iso-filecoin/src/rpc.js#L552-L579

filecoin/packages/iso-filecoin/src/rpc.js

Lines 557 to 561 in 950f30e

	if (safety === 'finalized' || safety === 'safe') {
	const ts = await this.lookBackTipSet(
	safety === 'finalized' ? 900 : 30,
	fetchOptions
	)