feat: ExpectedRewardForPower builtin utility function

[rvagg]

And lotus-shed miner expected-reward CLI command

Ref: #13137

[Copilot]

Pull Request Overview

This PR introduces the ExpectedRewardForPower builtin utility function and ties it into the CLI via a new "expected-reward" command for miners. Key changes include:

• Adding the minerExpectedRewardCmd to the CLI commands in cmd/lotus-shed/miner.go.
• Updating miner-fees-related code to import the required reward package and parse the qapower argument.
• Implementing the ExpectedRewardForPower function in the miner actor code and updating the actor code template to support actor versions ≥13.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
cmd/lotus-shed/miner.go	Added new CLI command for expected reward computation
cmd/lotus-shed/miner-fees.go	Updated imports and added logic for the new CLI command
chain/actors/builtin/miner/miner.go	Added ExpectedRewardForPower utility function supporting multiple versions
chain/actors/builtin/miner/actor.go.template	Updated template to utilize the new ExpectedRewardForPower function

PR title now matches the required format.

[Copilot]

Pull Request Overview

Adds a new ExpectedRewardForPower utility in the miner actor package and exposes it via a lotus-shed miner expected-reward CLI command to project miner rewards over a given epoch window.

• Introduce ExpectedRewardForPower function with version‐aware dispatch in chain/actors/builtin/miner
• Add miner expected-reward CLI command in cmd/lotus-shed/miner-fees.go and register it in miner.go
• Update actor code template and changelog

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
cmd/lotus-shed/miner.go	Registered minerExpectedRewardCmd under the miner commands
cmd/lotus-shed/miner-fees.go	Implemented the expected-reward command and tipset/flag parsing
chain/actors/builtin/miner/miner.go	Added ExpectedRewardForPower utility with version switch
chain/actors/builtin/miner/actor.go.template	Updated template to generate ExpectedRewardForPower for v13+
CHANGELOG.md	Documented the new utility and CLI command

Comments suppressed due to low confidence (2)

chain/actors/builtin/miner/miner.go:488

• No unit tests were added for ExpectedRewardForPower; consider adding tests that cover multiple network versions and edge cases to prevent regressions.

func ExpectedRewardForPower(

cmd/lotus-shed/miner-fees.go:676

• [nitpick] The variable name rew is ambiguous; renaming it to expectedReward would improve clarity.

rew, err := minertypes.ExpectedRewardForPower(nv, rewardSmoothed, powerSmoothed, qapower, projectionPeriod)

[rvagg]

$ lotus-shed miner expected-reward --help
NAME:
   lotus-shed miner expected-reward - Calculate the expected block reward for a miner over a specified projection period (e.g. lotus-shed miner expected-reward --tipset @head --projection-period 1025280 --qapower 69793218560)

USAGE:
   lotus-shed miner expected-reward [command options]

OPTIONS:
   --tipset value             tipset or height (@X or @head for latest) (default: "@head")
   --projection-period value  number of epochs to project reward for (default: 2880)
   --qapower value            Quality Adjusted Power in bytes (default: 34359738368)
   --help, -h                 show help

$ lotus-shed miner expected-reward
Expected reward for 34359738368 bytes of QA power @ epoch 4988993 for 2880 epochs: 111843816440699 attoFIL

$ lotus-shed miner expected-reward --tipset @head --projection-period 1025280 --qapower 69793218560
Expected reward for 69793218560 bytes of QA power @ epoch 4988993 for 1025280 epochs: 63927803959250660 attoFIL

[BigLep]

@rvagg : I assume you'll merge?