move custody-specific operations to custody spec

specs/custody/custody-game.md

@@ -39,6 +39,7 @@
   - [`get_randao_epoch_for_custody_period`](#get_randao_epoch_for_custody_period)
   - [`get_custody_period_for_validator`](#get_custody_period_for_validator)
 - [Per-block processing](#per-block-processing)
+  - [Block processing](#block-processing)
   - [Custody Game Operations](#custody-game-operations)
     - [Chunk challenges](#chunk-challenges)
     - [Custody chunk response](#custody-chunk-response)
@@ -46,6 +47,7 @@
     - [Early derived secret reveals](#early-derived-secret-reveals)
     - [Custody Slashings](#custody-slashings)
 - [Per-epoch processing](#per-epoch-processing)
+  - [Epoch transition](#epoch-transition)
   - [Handling of reveal deadlines](#handling-of-reveal-deadlines)
   - [Final updates](#final-updates)
 
@@ -348,6 +350,18 @@ def get_custody_period_for_validator(validator_index: ValidatorIndex, epoch: Epo
 
 ## Per-block processing
 
+### Block processing
+
+```python
+def process_block(state: BeaconState, block: BeaconBlock) -> None:
+    process_block_header(state, block)
+    process_randao(state, block.body)
+    process_eth1_data(state, block.body)
+    process_light_client_aggregate(state, block.body)
+    process_operations(state, block.body)
+    process_custody_game_operations(state, block.body)
+```
+
 ### Custody Game Operations
 
 ```python
@@ -605,6 +619,41 @@ def process_custody_slashing(state: BeaconState, signed_custody_slashing: Signed
 
 ## Per-epoch processing
 
+### Epoch transition
+
+This epoch transition overrides the phase0 epoch transition:
+
+```python
+def process_epoch(state: BeaconState) -> None:
+    process_justification_and_finalization(state)
+    process_rewards_and_penalties(state)
+    process_registry_updates(state)
+
+    # Proof of custody
+    process_reveal_deadlines(state)
+    process_challenge_deadlines(state)
+
+    process_slashings(state)
+
+    # Sharding
+    process_pending_headers(state)
+    charge_confirmed_header_fees(state)
+    reset_pending_headers(state)
+
+    # Final updates
+    # Phase 0
+    process_eth1_data_reset(state)
+    process_effective_balance_updates(state)
+    process_slashings_reset(state)
+    process_randao_mixes_reset(state)
+    process_historical_roots_update(state)
+    process_participation_record_updates(state)
+    # Proof of custody
+    process_custody_final_updates(state)
+
+    process_shard_epoch_increment(state)
+```
+
 ### Handling of reveal deadlines
 
 ```python

specs/sharding/beacon-chain.md

@@ -49,7 +49,7 @@
     - [`process_shard_header`](#process_shard_header)
   - [Epoch transition](#epoch-transition)
     - [Pending headers](#pending-headers)
-    - [Custody game updates](#custody-game-updates)
+    - [Shard epoch increment](#shard-epoch-increment)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->
@@ -125,7 +125,7 @@ We define the following Python custom types for type hinting and readability:
 
 ## Updated containers
 
-The following containers have updated definitions in Phase 1.
+The following containers have updated definitions to support Sharding.
 
 ### `AttestationData`
 
@@ -167,7 +167,8 @@ class BeaconState(phase0.BeaconState):
 
 ## New containers
 
-The following containers are new in Phase 1.
+The shard data itself is network-layer only, and can be found in the [P2P specification](./p2p-interface.md).
+The beacon chain registers just the commitments of the shard data.
 
 ### `DataCommitment`
 
@@ -435,9 +436,6 @@ def process_operations(state: BeaconState, body: BeaconBlockBody) -> None:
     for_ops(body.attestations, process_attestation)
     for_ops(body.deposits, process_deposit)
     for_ops(body.voluntary_exits, process_voluntary_exit)
-
-    # See custody game spec.
-    process_custody_game_operations(state, body)
 ```
 
 ### New Attestation processing
@@ -550,10 +548,6 @@ def process_epoch(state: BeaconState) -> None:
     process_rewards_and_penalties(state)
     process_registry_updates(state)
 
-    # Proof of custody
-    process_reveal_deadlines(state)
-    process_challenge_deadlines(state)
-
     process_slashings(state)
 
     # Sharding
@@ -569,10 +563,8 @@ def process_epoch(state: BeaconState) -> None:
     process_randao_mixes_reset(state)
     process_historical_roots_update(state)
     process_participation_record_updates(state)
-    # Proof of custody
-    process_custody_final_updates(state)
-    # Update current_epoch_start_shard
-    state.current_epoch_start_shard = get_start_shard(state, Slot(state.slot + 1))
+
+    process_shard_epoch_increment(state)
 ```
 
 #### Pending headers
@@ -682,6 +674,10 @@ def reset_pending_headers(state: BeaconState) -> None:
             ))
 ```
 
-#### Custody game updates
+#### Shard epoch increment
 
-`process_reveal_deadlines`, `process_challenge_deadlines` and `process_custody_final_updates` are defined in [the Custody Game spec](./custody-game.md).
+```python
+def process_shard_epoch_increment(state: BeaconState) -> None:
+    # Update current_epoch_start_shard
+    state.current_epoch_start_shard = get_start_shard(state, Slot(state.slot + 1))
+```