Move confirmation rule specs to Bellatrix

setup.py

@@ -397,10 +397,6 @@ def finalize_options(self):
             print("no paths were specified, using default markdown file paths for pyspec"
                   " build (spec fork: %s)" % self.spec_fork)
             self.md_doc_paths = get_md_doc_paths(self.spec_fork)
-            if self.spec_fork not in ('phase0', 'altair'):
-                self.md_doc_paths += """
-                    fork_choice/confirmation-rule.md
-                """
             if len(self.md_doc_paths) == 0:
                 raise Exception('no markdown files specified, and spec fork "%s" is unknown', self.spec_fork)
 

specs/_features/eip7732/confirmation-rule.md

@@ -0,0 +1,60 @@
+# Fork Choice -- Confirmation Rule
+
+## Table of contents
+<!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+
+- [Confirmation Rule](#confirmation-rule)
+  - [Helper Functions](#helper-functions)
+    - [Modified `get_ffg_support`](#modified-get_ffg_support)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+<!-- /TOC -->
+
+## Confirmation Rule
+
+### Helper Functions
+
+#### Modified `get_ffg_support`
+
+```python
+def get_ffg_support(store: Store, checkpoint: Root) -> Gwei:
+    """
+    Returns the total weight supporting the checkpoint in the block's chain at block's epoch.
+    """
+    current_epoch = get_current_store_epoch(store)
+
+    # This function is only applicable to current and previous epoch blocks
+    assert current_epoch in [checkpoint.epoch, checkpoint.epoch + 1]
+
+    if checkpoint not in store.checkpoint_states:
+        return Gwei(0)
+
+    checkpoint_state = store.checkpoint_states[checkpoint]
+
+    leaf_roots = [
+        leaf for leaf in get_leaf_block_roots(store, checkpoint.root)
+        if get_checkpoint_block(store, leaf, checkpoint.epoch) == checkpoint.root]
+
+    active_checkpoint_indices = get_active_validator_indices(checkpoint_state, checkpoint.epoch)
+    participating_indices_from_blocks = set().union(*[
+        get_epoch_participating_indices(
+            store.block_states[root],
+            active_checkpoint_indices,
+            checkpoint.epoch == current_epoch
+        )
+        for root in leaf_roots
+    ])
+
+    participating_indices_from_lmds = set([
+        i
+        for i in store.latest_messages
+        if get_checkpoint_block(
+            store, store.latest_messages[i].root,
+            compute_epoch_at_slot(store.latest_messages[i].slot),  # Modified in EIP7732
+        ) == checkpoint.root
+    ])
+
+    return get_total_balance(checkpoint_state, participating_indices_from_blocks.union(participating_indices_from_lmds))
+```

specs/bellatrix/fork-choice.md

@@ -13,6 +13,7 @@
       - [`safe_block_hash`](#safe_block_hash)
       - [`should_override_forkchoice_update`](#should_override_forkchoice_update)
 - [Helpers](#helpers)
+  - [Modified `Store`](#modified-store)
   - [`PayloadAttributes`](#payloadattributes)
   - [`PowBlock`](#powblock)
   - [`get_pow_block`](#get_pow_block)
@@ -159,6 +160,32 @@ the result of `should_override_forkchoice_update` (when proposer reorgs are enab
 
 ## Helpers
 
+### Modified `Store` 
+
+*Note*: It's not a hard fork change. `highest_confirmed_block_current_epoch`, `highest_confirmed_block_previous_epoch`, and `leaves_last_slot_previous_epoch` are added for [confirmation rule](confirmation-rule.md).
+
+```python
+@dataclass
+class Store(object):
+    time: uint64
+    genesis_time: uint64
+    justified_checkpoint: Checkpoint
+    finalized_checkpoint: Checkpoint
+    unrealized_justified_checkpoint: Checkpoint
+    unrealized_finalized_checkpoint: Checkpoint
+    proposer_boost_root: Root
+    highest_confirmed_block_current_epoch: Root  # New for confirmation rule
+    highest_confirmed_block_previous_epoch: Root  # New for confirmation rule
+    leaves_last_slot_previous_epoch: Set[Root]  # New for confirmation rule
+    equivocating_indices: Set[ValidatorIndex]
+    blocks: Dict[Root, BeaconBlock] = field(default_factory=dict)
+    block_states: Dict[Root, BeaconState] = field(default_factory=dict)
+    block_timeliness: Dict[Root, boolean] = field(default_factory=dict)
+    checkpoint_states: Dict[Checkpoint, BeaconState] = field(default_factory=dict)
+    latest_messages: Dict[ValidatorIndex, LatestMessage] = field(default_factory=dict)
+    unrealized_justifications: Dict[Root, Checkpoint] = field(default_factory=dict)
+```
+
 ### `PayloadAttributes`
 
 Used to signal to initiate the payload build process via `notify_forkchoice_updated`.