## Issue Addressed

The current `lcli` block packing code has an off-by-one where it would include an extra slot (the oldest slot) of attestations as "available" (this means there would be 33 slots of "available" attestations instead of 32).
There is typically only single-digit attestations remaining from that slot and as such does not cause a significant change to the results although every efficiency will have been very slightly under-reported.

## Proposed Changes

Prune the `available_attestation_set` before writing out the data instead of after.

## Additional Info

This `lcli` code will soon be deprecated by a Lighthouse API (#2879)  which will run significantly faster and will be used to hook into our upcoming monitoring platform #2873.

## Issue Addressed
N/A

## Proposed Changes
Add a HTTP API which can be used to compute the block packing data for all blocks over a discrete range of epochs.

## Usage
### Request
```
curl "http:localhost:5052/lighthouse/analysis/block_packing_efficiency?start_epoch=57730&end_epoch=57732"
```
### Response
```
[
  {
    "slot": "1847360",
    "block_hash": "0xa7dc230659802df2f99ea3798faede2e75942bb5735d56e6bfdc2df335dcd61f",
    "proposer_info": {
      "validator_index": 1686,
      "graffiti": ""
    },
    "available_attestations": 7096,
    "included_attestations": 6459,
    "prior_skip_slots": 0
  },
  ...
]
```
## Additional Info

This is notably different to the existing lcli code:
- Uses `BlockReplayer` #2863 and as such runs significantly faster than the previous method.
- Corrects the off-by-one #2878
- Removes the `offline` validators component. This was only a "best guess" and simply was used as a way to determine an estimate of the "true" packing efficiency and was generally not helpful in terms of direct comparisons between different packing methods. As such it has been removed from the API and any future estimates of "offline" validators would be better suited in a separate/more targeted API or as part of 'beacon watch': #2873 
- Includes `prior_skip_slots`.

## Issue Addressed
N/A

## Proposed Changes
Add a HTTP API which can be used to compute the block packing data for all blocks over a discrete range of epochs.

## Usage
### Request
```
curl "http:localhost:5052/lighthouse/analysis/block_packing_efficiency?start_epoch=57730&end_epoch=57732"
```
### Response
```
[
  {
    "slot": "1847360",
    "block_hash": "0xa7dc230659802df2f99ea3798faede2e75942bb5735d56e6bfdc2df335dcd61f",
    "proposer_info": {
      "validator_index": 1686,
      "graffiti": ""
    },
    "available_attestations": 7096,
    "included_attestations": 6459,
    "prior_skip_slots": 0
  },
  ...
]
```
## Additional Info

This is notably different to the existing lcli code:
- Uses `BlockReplayer` #2863 and as such runs significantly faster than the previous method.
- Corrects the off-by-one #2878
- Removes the `offline` validators component. This was only a "best guess" and simply was used as a way to determine an estimate of the "true" packing efficiency and was generally not helpful in terms of direct comparisons between different packing methods. As such it has been removed from the API and any future estimates of "offline" validators would be better suited in a separate/more targeted API or as part of 'beacon watch': #2873 
- Includes `prior_skip_slots`.

## Issue Addressed
N/A

## Proposed Changes
Add a HTTP API which can be used to compute the block packing data for all blocks over a discrete range of epochs.

## Usage
### Request
```
curl "http:localhost:5052/lighthouse/analysis/block_packing_efficiency?start_epoch=57730&end_epoch=57732"
```
### Response
```
[
  {
    "slot": "1847360",
    "block_hash": "0xa7dc230659802df2f99ea3798faede2e75942bb5735d56e6bfdc2df335dcd61f",
    "proposer_info": {
      "validator_index": 1686,
      "graffiti": ""
    },
    "available_attestations": 7096,
    "included_attestations": 6459,
    "prior_skip_slots": 0
  },
  ...
]
```
## Additional Info

This is notably different to the existing lcli code:
- Uses `BlockReplayer` #2863 and as such runs significantly faster than the previous method.
- Corrects the off-by-one #2878
- Removes the `offline` validators component. This was only a "best guess" and simply was used as a way to determine an estimate of the "true" packing efficiency and was generally not helpful in terms of direct comparisons between different packing methods. As such it has been removed from the API and any future estimates of "offline" validators would be better suited in a separate/more targeted API or as part of 'beacon watch': #2873 
- Includes `prior_skip_slots`.

## Issue Addressed
N/A

## Proposed Changes
Add a HTTP API which can be used to compute the block packing data for all blocks over a discrete range of epochs.

## Usage
### Request
```
curl "http:localhost:5052/lighthouse/analysis/block_packing_efficiency?start_epoch=57730&end_epoch=57732"
```
### Response
```
[
  {
    "slot": "1847360",
    "block_hash": "0xa7dc230659802df2f99ea3798faede2e75942bb5735d56e6bfdc2df335dcd61f",
    "proposer_info": {
      "validator_index": 1686,
      "graffiti": ""
    },
    "available_attestations": 7096,
    "included_attestations": 6459,
    "prior_skip_slots": 0
  },
  ...
]
```
## Additional Info

This is notably different to the existing lcli code:
- Uses `BlockReplayer` #2863 and as such runs significantly faster than the previous method.
- Corrects the off-by-one #2878
- Removes the `offline` validators component. This was only a "best guess" and simply was used as a way to determine an estimate of the "true" packing efficiency and was generally not helpful in terms of direct comparisons between different packing methods. As such it has been removed from the API and any future estimates of "offline" validators would be better suited in a separate/more targeted API or as part of 'beacon watch': #2873 
- Includes `prior_skip_slots`.