From b029c75d88f911902228b92668b7d0d8f17a894e Mon Sep 17 00:00:00 2001
From: Danny Ryan <dannyjryan@gmail.com>
Date: Mon, 1 Feb 2021 07:52:06 -0700
Subject: [PATCH 1/9] must be correct target to get correct head

---
 specs/lightclient/beacon-chain.md             |  2 +-
 .../pyspec/eth2spec/test/helpers/rewards.py   | 19 +++++++++++++------
 .../test/phase0/rewards/test_random.py        |  6 ++++++
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/specs/lightclient/beacon-chain.md b/specs/lightclient/beacon-chain.md
index bb00a5c59..bcb90f756 100644
--- a/specs/lightclient/beacon-chain.md
+++ b/specs/lightclient/beacon-chain.md
@@ -374,7 +374,7 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
 
     # Participation flags
     participation_flags = []
-    if is_matching_head and state.slot <= data.slot + MIN_ATTESTATION_INCLUSION_DELAY:
+    if is_matching_head and is_matching_target and state.slot <= data.slot + MIN_ATTESTATION_INCLUSION_DELAY:
         participation_flags.append(TIMELY_HEAD_FLAG)
     if is_matching_source and state.slot <= data.slot + integer_squareroot(SLOTS_PER_EPOCH):
         participation_flags.append(TIMELY_SOURCE_FLAG)
diff --git a/tests/core/pyspec/eth2spec/test/helpers/rewards.py b/tests/core/pyspec/eth2spec/test/helpers/rewards.py
index 770519384..81eb1f955 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/rewards.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/rewards.py
@@ -517,11 +517,18 @@ def run_test_full_random(spec, state, rng=Random(8020)):
             pending_attestation.inclusion_delay = rng.randint(1, spec.SLOTS_PER_EPOCH)
     else:
         for index in range(len(state.validators)):
-            # ~1/3 have bad target
-            state.previous_epoch_participation[index][spec.TIMELY_TARGET_FLAG] = rng.randint(0, 2) != 0
-            # ~1/3 have bad head
-            state.previous_epoch_participation[index][spec.TIMELY_HEAD_FLAG] = rng.randint(0, 2) != 0
-            # ~50% participation
-            state.previous_epoch_participation[index][spec.TIMELY_SOURCE_FLAG] = rng.choice([True, False])
+            # ~1/3 have bad head or bad target or not timely enough
+            is_timely_correct_head = rng.randint(0, 2) != 0
+            state.previous_epoch_participation[index][spec.TIMELY_HEAD_FLAG] = is_timely_correct_head
+            if is_timely_correct_head:
+                # If timely head, then must be timely target
+                state.previous_epoch_participation[index][spec.TIMELY_TARGET_FLAG] = True
+                # If timely head, then must be timely source
+                state.previous_epoch_participation[index][spec.TIMELY_SOURCE_FLAG] = True
+            else:
+                # ~50% of remaining have bad target or not timely enough
+                state.previous_epoch_participation[index][spec.TIMELY_TARGET_FLAG] = rng.choice([True, False])
+                # ~50% of remaining have bad source or not timely enough
+                state.previous_epoch_participation[index][spec.TIMELY_SOURCE_FLAG] = rng.choice([True, False])
 
     yield from run_deltas(spec, state)
diff --git a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
index 83c7f7905..ae44c6640 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
@@ -29,6 +29,12 @@ def test_full_random_2(spec, state):
     yield from rewards_helpers.run_test_full_random(spec, state, rng=Random(3030))
 
 
+@with_all_phases
+@spec_state_test
+def test_full_random_3(spec, state):
+    yield from rewards_helpers.run_test_full_random(spec, state, rng=Random(4040))
+
+
 @with_all_phases
 @with_custom_state(balances_fn=low_balances, threshold_fn=lambda spec: spec.EJECTION_BALANCE)
 @spec_test

From 1ba491711947b4f908bd68b0639584b11c20442c Mon Sep 17 00:00:00 2001
From: Danny Ryan <dannyjryan@gmail.com>
Date: Mon, 1 Feb 2021 08:35:58 -0700
Subject: [PATCH 2/9] add process_attestation tests to cover various timing and
 correctness scenarios

---
 .../eth2spec/test/helpers/attestations.py     |   7 +-
 .../test_process_attestation.py               | 159 +++++++++++++++++-
 2 files changed, 160 insertions(+), 6 deletions(-)

diff --git a/tests/core/pyspec/eth2spec/test/helpers/attestations.py b/tests/core/pyspec/eth2spec/test/helpers/attestations.py
index cf62482da..571e19fef 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/attestations.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/attestations.py
@@ -44,11 +44,8 @@ def run_attestation_processing(spec, state, attestation, valid=True):
         else:
             assert len(state.previous_epoch_attestations) == previous_epoch_count + 1
     else:
-        for index in spec.get_attesting_indices(state, attestation.data, attestation.aggregation_bits):
-            if attestation.data.target.epoch == spec.get_current_epoch(state):
-                assert state.current_epoch_participation[index][spec.TIMELY_TARGET_FLAG]
-            else:
-                assert state.previous_epoch_participation[index][spec.TIMELY_TARGET_FLAG]
+        # After accounting reform, there are cases when processing an attestation does not result in any flag updates
+        pass
 
     # yield post-state
     yield 'post', state
diff --git a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attestation.py b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attestation.py
index b31cf167c..71000763b 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attestation.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attestation.py
@@ -2,10 +2,13 @@ from eth2spec.test.context import (
     spec_state_test,
     always_bls, never_bls,
     with_all_phases,
+    with_all_phases_except,
     spec_test,
     low_balances,
     with_custom_state,
-    single_phase)
+    single_phase,
+    PHASE1,
+)
 from eth2spec.test.helpers.attestations import (
     run_attestation_processing,
     get_valid_attestation,
@@ -329,3 +332,157 @@ def test_too_few_aggregation_bits(spec, state):
     attestation.aggregation_bits = attestation.aggregation_bits[:-1]
 
     yield from run_attestation_processing(spec, state, attestation, False)
+
+
+#
+# Full correct atttestation contents at different slot inclusions
+#
+
+@with_all_phases
+@spec_state_test
+def test_correct_min_inclusion_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=True)
+    next_slots(spec, state, spec.MIN_ATTESTATION_INCLUSION_DELAY)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+@with_all_phases
+@spec_state_test
+def test_correct_sqrt_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=True, on_time=False)
+    next_slots(spec, state, spec.integer_squareroot(spec.SLOTS_PER_EPOCH))
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+@with_all_phases
+@spec_state_test
+def test_correct_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=True, on_time=False)
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+#
+# Incorrect head but correct source/target at different slot inclusions
+#
+
+@with_all_phases_except([PHASE1])
+@spec_state_test
+def test_incorrect_head_min_inclusion_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False)
+    next_slots(spec, state, spec.MIN_ATTESTATION_INCLUSION_DELAY)
+
+    attestation.data.beacon_block_root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+@with_all_phases
+@spec_state_test
+def test_incorrect_head_sqrt_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False, on_time=False)
+    next_slots(spec, state, spec.integer_squareroot(spec.SLOTS_PER_EPOCH))
+
+    attestation.data.beacon_block_root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+@with_all_phases
+@spec_state_test
+def test_incorrect_head_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False, on_time=False)
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH)
+
+    attestation.data.beacon_block_root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+#
+# Incorrect head and target but correct source at different slot inclusions
+#
+
+@with_all_phases_except([PHASE1])
+@spec_state_test
+def test_incorrect_head_and_target_min_inclusion_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False)
+    next_slots(spec, state, spec.MIN_ATTESTATION_INCLUSION_DELAY)
+
+    attestation.data.beacon_block_root = b'\x42' * 32
+    attestation.data.target.root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+@with_all_phases
+@spec_state_test
+def test_incorrect_head_and_target_sqrt_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False, on_time=False)
+    next_slots(spec, state, spec.integer_squareroot(spec.SLOTS_PER_EPOCH))
+
+    attestation.data.beacon_block_root = b'\x42' * 32
+    attestation.data.target.root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+@with_all_phases
+@spec_state_test
+def test_incorrect_head_and_target_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False, on_time=False)
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH)
+
+    attestation.data.beacon_block_root = b'\x42' * 32
+    attestation.data.target.root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+#
+# Correct head and source but incorrect target at different slot inclusions
+#
+
+@with_all_phases_except([PHASE1])
+@spec_state_test
+def test_incorrect_target_min_inclusion_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False)
+    next_slots(spec, state, spec.MIN_ATTESTATION_INCLUSION_DELAY)
+
+    attestation.data.target.root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+@with_all_phases
+@spec_state_test
+def test_incorrect_target_sqrt_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False, on_time=False)
+    next_slots(spec, state, spec.integer_squareroot(spec.SLOTS_PER_EPOCH))
+
+    attestation.data.target.root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation)
+
+
+@with_all_phases
+@spec_state_test
+def test_incorrect_target_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False, on_time=False)
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH)
+
+    attestation.data.target.root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation)

From 3677073812c02c2ed613e14d874e444b97a89210 Mon Sep 17 00:00:00 2001
From: protolambda <proto@protolambda.com>
Date: Mon, 1 Feb 2021 21:46:27 +0100
Subject: [PATCH 3/9] bitvector[8] -> uint8, for efficient packing in flags
 merkle tree

---
 specs/lightclient/beacon-chain.md             | 53 +++++++++++++------
 specs/lightclient/lightclient-fork.md         |  4 +-
 .../pyspec/eth2spec/test/helpers/rewards.py   | 29 ++++++----
 ..._process_justification_and_finalization.py |  6 +--
 .../test/phase0/sanity/test_blocks.py         |  2 +-
 5 files changed, 63 insertions(+), 31 deletions(-)

diff --git a/specs/lightclient/beacon-chain.md b/specs/lightclient/beacon-chain.md
index bcb90f756..1ac6d2a2c 100644
--- a/specs/lightclient/beacon-chain.md
+++ b/specs/lightclient/beacon-chain.md
@@ -55,15 +55,26 @@ This is a patch implementing the first hard fork to the beacon chain, tentativel
   and [TODO] reducing the cost of processing chains that have very little or zero participation for a long span of epochs
 * Fork choice rule changes to address weaknesses recently discovered in the existing fork choice
 
+## Custom types
+
+| Name | SSZ equivalent | Description |
+| - | - | - |
+| `ValidatorFlags` | `uint8` | Bitflags to track validator actions with |
+
 ## Constants
 
-### Participation flags
+### Validator action flags
+
+This is formatted as an enum, with values `2**i` that can be combined as bit-flags.
+The `0` value is reserved as default. Remaining bits in `ValidatorFlags` may be used in future hardforks.
+
+**Note**: unlike Phase0, a `TIMELY_TARGET_FLAG` does not imply a `TIMELY_SOURCE_FLAG`.
 
 | Name | Value |
 | - | - |
-| `TIMELY_HEAD_FLAG` | `0` |
-| `TIMELY_SOURCE_FLAG` | `1` |
-| `TIMELY_TARGET_FLAG` | `2` |
+| `TIMELY_HEAD_FLAG`   | `ValidatorFlags(2**0)` (= 1) |
+| `TIMELY_SOURCE_FLAG` | `ValidatorFlags(2**1)` (= 2) |
+| `TIMELY_TARGET_FLAG` | `ValidatorFlags(2**2)` (= 4) |
 
 ### Participation rewards
 
@@ -80,7 +91,6 @@ The reward fractions add up to 7/8, leaving the remaining 1/8 for proposer rewar
 
 | Name | Value |
 | - | - |
-| `PARTICIPATION_FLAGS_LENGTH` | `8` |
 | `G2_POINT_AT_INFINITY` | `BLSSignature(b'\xc0' + b'\x00' * 95)` |
 
 ## Configuration
@@ -146,8 +156,8 @@ class BeaconState(Container):
     # Slashings
     slashings: Vector[Gwei, EPOCHS_PER_SLASHINGS_VECTOR]  # Per-epoch sums of slashed effective balances
     # Participation
-    previous_epoch_participation: List[Bitvector[PARTICIPATION_FLAGS_LENGTH], VALIDATOR_REGISTRY_LIMIT]
-    current_epoch_participation: List[Bitvector[PARTICIPATION_FLAGS_LENGTH], VALIDATOR_REGISTRY_LIMIT]
+    previous_epoch_participation: List[ValidatorFlags, VALIDATOR_REGISTRY_LIMIT]
+    current_epoch_participation: List[ValidatorFlags, VALIDATOR_REGISTRY_LIMIT]
     # Finality
     justification_bits: Bitvector[JUSTIFICATION_BITS_LENGTH]  # Bit set for every recent justified epoch
     previous_justified_checkpoint: Checkpoint
@@ -197,7 +207,15 @@ def get_flags_and_numerators() -> Sequence[Tuple[int, int]]:
     )
 ```
 
+```python
+def add_flags(flags: ValidatorFlags, add: ValidatorFlags) -> ValidatorFlags:
+    return flags | add
+```
 
+```python
+def has_flags(flags: ValidatorFlags, has: ValidatorFlags) -> bool:
+    return flags & has == has
+```
 
 ### Beacon state accessors
 
@@ -257,7 +275,10 @@ def get_base_reward(state: BeaconState, index: ValidatorIndex) -> Gwei:
 #### `get_unslashed_participating_indices`
 
 ```python
-def get_unslashed_participating_indices(state: BeaconState, flag: uint8, epoch: Epoch) -> Set[ValidatorIndex]:
+def get_unslashed_participating_indices(state: BeaconState, flags: ValidatorFlags, epoch: Epoch) -> Set[ValidatorIndex]:
+    """
+    Retrieves the active validator indices of the given epoch, who are not slashed, and have all of the given flags. 
+    """
     assert epoch in (get_previous_epoch(state), get_current_epoch(state))
     if epoch == get_current_epoch(state):
         epoch_participation = state.current_epoch_participation
@@ -265,7 +286,7 @@ def get_unslashed_participating_indices(state: BeaconState, flag: uint8, epoch:
         epoch_participation = state.previous_epoch_participation
     participating_indices = [
         index for index in get_active_validator_indices(state, epoch)
-        if epoch_participation[index][flag]
+        if has_flags(epoch_participation[index], flags)
     ]
     return set(filter(lambda index: not state.validators[index].slashed, participating_indices))
 ```
@@ -273,7 +294,9 @@ def get_unslashed_participating_indices(state: BeaconState, flag: uint8, epoch:
 #### `get_flag_deltas`
 
 ```python
-def get_flag_deltas(state: BeaconState, flag: uint8, numerator: uint64) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
+def get_flag_deltas(state: BeaconState,
+                    flag: ValidatorFlags,
+                    numerator: uint64) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
     """
     Computes the rewards and penalties associated with a particular duty, by scanning through the participation
     flags to determine who participated and who did not and assigning them the appropriate rewards and penalties.
@@ -385,8 +408,8 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
     proposer_reward_numerator = 0
     for index in get_attesting_indices(state, data, attestation.aggregation_bits):
         for flag, numerator in get_flags_and_numerators():
-            if flag in participation_flags and not epoch_participation[index][flag]:
-                epoch_participation[index][flag] = True
+            if flag in participation_flags and not has_flags(epoch_participation[index], flag):
+                epoch_participation[index] = add_flags(epoch_participation[index], flag)
                 proposer_reward_numerator += get_base_reward(state, index) * numerator
 
     # Reward proposer
@@ -432,8 +455,8 @@ def process_deposit(state: BeaconState, deposit: Deposit) -> None:
         state.validators.append(get_validator_from_deposit(state, deposit))
         state.balances.append(amount)
         # [Added in hf-1] Initialize empty participation flags for new validator
-        state.previous_epoch_participation.append(Bitvector[PARTICIPATION_FLAGS_LENGTH]())
-        state.current_epoch_participation.append(Bitvector[PARTICIPATION_FLAGS_LENGTH]())
+        state.previous_epoch_participation.append(ValidatorFlags(0))
+        state.current_epoch_participation.append(ValidatorFlags(0))
     else:
         # Increase balance by deposit amount
         index = ValidatorIndex(validator_pubkeys.index(pubkey))
@@ -572,5 +595,5 @@ def process_participation_flag_updates(state: BeaconState) -> None:
     Call to ``process_participation_flag_updates`` added to ``process_epoch`` in HF1
     """
     state.previous_epoch_participation = state.current_epoch_participation
-    state.current_epoch_participation = [Bitvector[PARTICIPATION_FLAGS_LENGTH]() for _ in range(len(state.validators))]
+    state.current_epoch_participation = [ValidatorFlags(0) for _ in range(len(state.validators))]
 ```
diff --git a/specs/lightclient/lightclient-fork.md b/specs/lightclient/lightclient-fork.md
index a10e8c5f6..f5f3d1b7b 100644
--- a/specs/lightclient/lightclient-fork.md
+++ b/specs/lightclient/lightclient-fork.md
@@ -67,8 +67,8 @@ def upgrade_to_lightclient_patch(pre: phase0.BeaconState) -> BeaconState:
         # Slashings
         slashings=pre.slashings,
         # Attestations
-        previous_epoch_participation=[Bitvector[PARTICIPATION_FLAGS_LENGTH]() for _ in range(len(pre.validators))],
-        current_epoch_participation=[Bitvector[PARTICIPATION_FLAGS_LENGTH]() for _ in range(len(pre.validators))],
+        previous_epoch_participation=[ValidatorFlags(0) for _ in range(len(pre.validators))],
+        current_epoch_participation=[ValidatorFlags(0) for _ in range(len(pre.validators))],
         # Finality
         justification_bits=pre.justification_bits,
         previous_justified_checkpoint=pre.previous_justified_checkpoint,
diff --git a/tests/core/pyspec/eth2spec/test/helpers/rewards.py b/tests/core/pyspec/eth2spec/test/helpers/rewards.py
index 81eb1f955..feaac018b 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/rewards.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/rewards.py
@@ -6,7 +6,7 @@ from eth2spec.test.context import is_post_lightclient_patch
 from eth2spec.test.helpers.attestations import cached_prepare_state_with_attestations
 from eth2spec.test.helpers.deposits import mock_deposit
 from eth2spec.test.helpers.state import next_epoch
-from eth2spec.utils.ssz.ssz_typing import Container, uint64, List, Bitvector
+from eth2spec.utils.ssz.ssz_typing import Container, uint64, List
 
 
 class Deltas(Container):
@@ -314,7 +314,7 @@ def run_test_full_but_partial_participation(spec, state, rng=Random(5522)):
     else:
         for index in range(len(state.validators)):
             if rng.choice([True, False]):
-                state.previous_epoch_participation[index] = Bitvector[spec.PARTICIPATION_FLAGS_LENGTH]()
+                state.previous_epoch_participation[index] = spec.ValidatorFlags(0)
 
     yield from run_deltas(spec, state)
 
@@ -328,7 +328,7 @@ def run_test_partial(spec, state, fraction_filled):
         state.previous_epoch_attestations = state.previous_epoch_attestations[:num_attestations]
     else:
         for index in range(int(len(state.validators) * fraction_filled)):
-            state.previous_epoch_participation[index] = Bitvector[spec.PARTICIPATION_FLAGS_LENGTH]()
+            state.previous_epoch_participation[index] = spec.ValidatorFlags(0)
 
     yield from run_deltas(spec, state)
 
@@ -394,7 +394,7 @@ def run_test_some_very_low_effective_balances_that_did_not_attest(spec, state):
     else:
         index = 0
         state.validators[index].effective_balance = 1
-        state.previous_epoch_participation[index] = Bitvector[spec.PARTICIPATION_FLAGS_LENGTH]()
+        state.previous_epoch_participation[index] = spec.ValidatorFlags(0)
 
     yield from run_deltas(spec, state)
 
@@ -519,16 +519,25 @@ def run_test_full_random(spec, state, rng=Random(8020)):
         for index in range(len(state.validators)):
             # ~1/3 have bad head or bad target or not timely enough
             is_timely_correct_head = rng.randint(0, 2) != 0
-            state.previous_epoch_participation[index][spec.TIMELY_HEAD_FLAG] = is_timely_correct_head
+            flags = state.previous_epoch_participation[index]
+
+            def set_flag(f, v):
+                nonlocal flags
+                if v:
+                    flags |= f
+                else:
+                    flags &= 0xff ^ f
+
+            set_flag(spec.TIMELY_HEAD_FLAG, is_timely_correct_head)
             if is_timely_correct_head:
                 # If timely head, then must be timely target
-                state.previous_epoch_participation[index][spec.TIMELY_TARGET_FLAG] = True
+                set_flag(spec.TIMELY_TARGET_FLAG, True)
                 # If timely head, then must be timely source
-                state.previous_epoch_participation[index][spec.TIMELY_SOURCE_FLAG] = True
+                set_flag(spec.TIMELY_SOURCE_FLAG, True)
             else:
                 # ~50% of remaining have bad target or not timely enough
-                state.previous_epoch_participation[index][spec.TIMELY_TARGET_FLAG] = rng.choice([True, False])
+                set_flag(spec.TIMELY_TARGET_FLAG, rng.choice([True, False]))
                 # ~50% of remaining have bad source or not timely enough
-                state.previous_epoch_participation[index][spec.TIMELY_SOURCE_FLAG] = rng.choice([True, False])
-
+                set_flag(spec.TIMELY_SOURCE_FLAG, rng.choice([True, False]))
+            state.previous_epoch_participation[index] = flags
     yield from run_deltas(spec, state)
diff --git a/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py b/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
index 0d1741efb..89783f987 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
@@ -78,10 +78,10 @@ def add_mock_attestations(spec, state, epoch, source, target, sufficient_support
             else:
                 for i, index in enumerate(committee):
                     if aggregation_bits[i]:
-                        epoch_participation[index][spec.TIMELY_HEAD_FLAG] = True
-                        epoch_participation[index][spec.TIMELY_SOURCE_FLAG] = True
+                        epoch_participation[index] |= spec.TIMELY_HEAD_FLAG
+                        epoch_participation[index] |= spec.TIMELY_SOURCE_FLAG
                         if not messed_up_target:
-                            epoch_participation[index][spec.TIMELY_TARGET_FLAG] = True
+                            epoch_participation[index] |= spec.TIMELY_TARGET_FLAG
 
 
 def get_checkpoints(spec, epoch):
diff --git a/tests/core/pyspec/eth2spec/test/phase0/sanity/test_blocks.py b/tests/core/pyspec/eth2spec/test/phase0/sanity/test_blocks.py
index 9cc8ab721..1834b290f 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/sanity/test_blocks.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/sanity/test_blocks.py
@@ -806,7 +806,7 @@ def test_attestation(spec, state):
         assert spec.hash_tree_root(state.previous_epoch_attestations) == pre_current_attestations_root
     else:
         for index in range(len(state.validators)):
-            assert state.current_epoch_participation[index] == spec.Bitvector[spec.PARTICIPATION_FLAGS_LENGTH]()
+            assert state.current_epoch_participation[index] == 0
         assert spec.hash_tree_root(state.previous_epoch_participation) == pre_current_epoch_participation_root
 
 

From e865670111c2fb89b7031f3ea6d67bf2426b03a9 Mon Sep 17 00:00:00 2001
From: protolambda <proto@protolambda.com>
Date: Mon, 1 Feb 2021 21:47:00 +0100
Subject: [PATCH 4/9] add missing decorators for testruns in no-bls mode

---
 .../block_processing/test_process_sync_committee.py            | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tests/core/pyspec/eth2spec/test/lightclient_patch/block_processing/test_process_sync_committee.py b/tests/core/pyspec/eth2spec/test/lightclient_patch/block_processing/test_process_sync_committee.py
index a8be1af63..430c59b10 100644
--- a/tests/core/pyspec/eth2spec/test/lightclient_patch/block_processing/test_process_sync_committee.py
+++ b/tests/core/pyspec/eth2spec/test/lightclient_patch/block_processing/test_process_sync_committee.py
@@ -18,6 +18,7 @@ from eth2spec.test.context import (
     with_all_phases_except,
     with_configs,
     spec_state_test,
+    always_bls,
 )
 from eth2spec.utils.hash_function import hash
 
@@ -196,6 +197,7 @@ def test_sync_committee_rewards_duplicate_committee(spec, state):
 
 @with_all_phases_except([PHASE0, PHASE1])
 @spec_state_test
+@always_bls
 def test_invalid_signature_past_block(spec, state):
     committee = spec.get_sync_committee_indices(state, spec.get_current_epoch(state))
 
@@ -237,6 +239,7 @@ def test_invalid_signature_past_block(spec, state):
 @with_all_phases_except([PHASE0, PHASE1])
 @with_configs([MINIMAL], reason="to produce different committee sets")
 @spec_state_test
+@always_bls
 def test_invalid_signature_previous_committee(spec, state):
     # NOTE: the `state` provided is at genesis and the process to select
     # sync committees currently returns the same committee for the first and second

From 71c28e67a13469ffc0452687f4ce6fad99a73107 Mon Sep 17 00:00:00 2001
From: protolambda <proto@protolambda.com>
Date: Mon, 1 Feb 2021 21:48:55 +0100
Subject: [PATCH 5/9] toc update

---
 specs/lightclient/beacon-chain.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/specs/lightclient/beacon-chain.md b/specs/lightclient/beacon-chain.md
index 1ac6d2a2c..179aec6d1 100644
--- a/specs/lightclient/beacon-chain.md
+++ b/specs/lightclient/beacon-chain.md
@@ -7,8 +7,9 @@
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 
 - [Introduction](#introduction)
+- [Custom types](#custom-types)
 - [Constants](#constants)
-  - [Participation flags](#participation-flags)
+  - [Validator action flags](#validator-action-flags)
   - [Participation rewards](#participation-rewards)
   - [Misc](#misc)
 - [Configuration](#configuration)

From b4ba6c57de0bb2138379a2e1761d5ab2bc3ed90e Mon Sep 17 00:00:00 2001
From: protolambda <proto@protolambda.com>
Date: Mon, 1 Feb 2021 22:02:12 +0100
Subject: [PATCH 6/9] linter: first tuple element type is ValidatorFlags, not
 just int

---
 specs/lightclient/beacon-chain.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/specs/lightclient/beacon-chain.md b/specs/lightclient/beacon-chain.md
index 179aec6d1..9f0572740 100644
--- a/specs/lightclient/beacon-chain.md
+++ b/specs/lightclient/beacon-chain.md
@@ -200,7 +200,7 @@ def eth2_fast_aggregate_verify(pubkeys: Sequence[BLSPubkey], message: Bytes32, s
 #### `flags_and_numerators`
 
 ```python
-def get_flags_and_numerators() -> Sequence[Tuple[int, int]]:
+def get_flags_and_numerators() -> Sequence[Tuple[ValidatorFlags, int]]:
     return (
         (TIMELY_HEAD_FLAG, TIMELY_HEAD_NUMERATOR),
         (TIMELY_SOURCE_FLAG, TIMELY_SOURCE_NUMERATOR),

From 1c1ba5cba291e725972601c62e97649565d1f299 Mon Sep 17 00:00:00 2001
From: Danny Ryan <dannyjryan@gmail.com>
Date: Tue, 2 Feb 2021 12:35:00 -0700
Subject: [PATCH 7/9] minor PR feedback

---
 specs/lightclient/beacon-chain.md             |  7 ++-
 .../test_process_attestation.py               | 55 +++++++++++++++++++
 2 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/specs/lightclient/beacon-chain.md b/specs/lightclient/beacon-chain.md
index 9f0572740..3508fe991 100644
--- a/specs/lightclient/beacon-chain.md
+++ b/specs/lightclient/beacon-chain.md
@@ -69,7 +69,8 @@ This is a patch implementing the first hard fork to the beacon chain, tentativel
 This is formatted as an enum, with values `2**i` that can be combined as bit-flags.
 The `0` value is reserved as default. Remaining bits in `ValidatorFlags` may be used in future hardforks.
 
-**Note**: unlike Phase0, a `TIMELY_TARGET_FLAG` does not imply a `TIMELY_SOURCE_FLAG`.
+**Note**: Unlike Phase0, a `TIMELY_TARGET_FLAG` does not necessarily imply a `TIMELY_SOURCE_FLAG`
+due to the varying slot delay requirements of each.
 
 | Name | Value |
 | - | - |
@@ -278,7 +279,7 @@ def get_base_reward(state: BeaconState, index: ValidatorIndex) -> Gwei:
 ```python
 def get_unslashed_participating_indices(state: BeaconState, flags: ValidatorFlags, epoch: Epoch) -> Set[ValidatorIndex]:
     """
-    Retrieves the active validator indices of the given epoch, who are not slashed, and have all of the given flags. 
+    Retrieve the active validator indices of the given epoch, which are not slashed, and have all of the given flags. 
     """
     assert epoch in (get_previous_epoch(state), get_current_epoch(state))
     if epoch == get_current_epoch(state):
@@ -299,7 +300,7 @@ def get_flag_deltas(state: BeaconState,
                     flag: ValidatorFlags,
                     numerator: uint64) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
     """
-    Computes the rewards and penalties associated with a particular duty, by scanning through the participation
+    Compute the rewards and penalties associated with a particular duty, by scanning through the participation
     flags to determine who participated and who did not and assigning them the appropriate rewards and penalties.
     """
     rewards = [Gwei(0)] * len(state.validators)
diff --git a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attestation.py b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attestation.py
index 71000763b..99a82879d 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attestation.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attestation.py
@@ -365,6 +365,17 @@ def test_correct_epoch_delay(spec, state):
     yield from run_attestation_processing(spec, state, attestation)
 
 
+@with_all_phases
+@spec_state_test
+def test_correct_after_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=True, on_time=False)
+
+    # increment past latest inclusion slot
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH + 1)
+
+    yield from run_attestation_processing(spec, state, attestation, False)
+
+
 #
 # Incorrect head but correct source/target at different slot inclusions
 #
@@ -405,10 +416,27 @@ def test_incorrect_head_epoch_delay(spec, state):
     yield from run_attestation_processing(spec, state, attestation)
 
 
+@with_all_phases
+@spec_state_test
+def test_incorrect_head_after_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False, on_time=False)
+
+    # increment past latest inclusion slot
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH + 1)
+
+    attestation.data.beacon_block_root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation, False)
+
+
 #
 # Incorrect head and target but correct source at different slot inclusions
 #
 
+# Note: current phase 1 spec checks
+# `assert data.beacon_block_root == get_block_root_at_slot(state, compute_previous_slot(state.slot))`
+# so this test can't pass that until phase 1 refactor is merged
 @with_all_phases_except([PHASE1])
 @spec_state_test
 def test_incorrect_head_and_target_min_inclusion_delay(spec, state):
@@ -448,6 +476,20 @@ def test_incorrect_head_and_target_epoch_delay(spec, state):
     yield from run_attestation_processing(spec, state, attestation)
 
 
+@with_all_phases
+@spec_state_test
+def test_incorrect_head_and_target_after_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False, on_time=False)
+    # increment past latest inclusion slot
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH + 1)
+
+    attestation.data.beacon_block_root = b'\x42' * 32
+    attestation.data.target.root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation, False)
+
+
 #
 # Correct head and source but incorrect target at different slot inclusions
 #
@@ -486,3 +528,16 @@ def test_incorrect_target_epoch_delay(spec, state):
     sign_attestation(spec, state, attestation)
 
     yield from run_attestation_processing(spec, state, attestation)
+
+
+@with_all_phases
+@spec_state_test
+def test_incorrect_target_after_epoch_delay(spec, state):
+    attestation = get_valid_attestation(spec, state, signed=False, on_time=False)
+    # increment past latest inclusion slot
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH + 1)
+
+    attestation.data.target.root = b'\x42' * 32
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation, False)

From 34cea67b91cd0d36504a6376c93e13c589832a7d Mon Sep 17 00:00:00 2001
From: Danny Ryan <dannyjryan@gmail.com>
Date: Thu, 4 Feb 2021 08:45:25 -0700
Subject: [PATCH 8/9] ValidatorFlags -> ValidatorFlag

---
 specs/lightclient/beacon-chain.md             | 30 +++++++++----------
 specs/lightclient/lightclient-fork.md         |  4 +--
 .../pyspec/eth2spec/test/helpers/rewards.py   |  6 ++--
 3 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/specs/lightclient/beacon-chain.md b/specs/lightclient/beacon-chain.md
index 3508fe991..ff69c1312 100644
--- a/specs/lightclient/beacon-chain.md
+++ b/specs/lightclient/beacon-chain.md
@@ -60,23 +60,23 @@ This is a patch implementing the first hard fork to the beacon chain, tentativel
 
 | Name | SSZ equivalent | Description |
 | - | - | - |
-| `ValidatorFlags` | `uint8` | Bitflags to track validator actions with |
+| `ValidatorFlag` | `uint8` | Bitflags to track validator actions with |
 
 ## Constants
 
 ### Validator action flags
 
 This is formatted as an enum, with values `2**i` that can be combined as bit-flags.
-The `0` value is reserved as default. Remaining bits in `ValidatorFlags` may be used in future hardforks.
+The `0` value is reserved as default. Remaining bits in `ValidatorFlag` may be used in future hardforks.
 
 **Note**: Unlike Phase0, a `TIMELY_TARGET_FLAG` does not necessarily imply a `TIMELY_SOURCE_FLAG`
 due to the varying slot delay requirements of each.
 
 | Name | Value |
 | - | - |
-| `TIMELY_HEAD_FLAG`   | `ValidatorFlags(2**0)` (= 1) |
-| `TIMELY_SOURCE_FLAG` | `ValidatorFlags(2**1)` (= 2) |
-| `TIMELY_TARGET_FLAG` | `ValidatorFlags(2**2)` (= 4) |
+| `TIMELY_HEAD_FLAG`   | `ValidatorFlag(2**0)` (= 1) |
+| `TIMELY_SOURCE_FLAG` | `ValidatorFlag(2**1)` (= 2) |
+| `TIMELY_TARGET_FLAG` | `ValidatorFlag(2**2)` (= 4) |
 
 ### Participation rewards
 
@@ -158,8 +158,8 @@ class BeaconState(Container):
     # Slashings
     slashings: Vector[Gwei, EPOCHS_PER_SLASHINGS_VECTOR]  # Per-epoch sums of slashed effective balances
     # Participation
-    previous_epoch_participation: List[ValidatorFlags, VALIDATOR_REGISTRY_LIMIT]
-    current_epoch_participation: List[ValidatorFlags, VALIDATOR_REGISTRY_LIMIT]
+    previous_epoch_participation: List[ValidatorFlag, VALIDATOR_REGISTRY_LIMIT]
+    current_epoch_participation: List[ValidatorFlag, VALIDATOR_REGISTRY_LIMIT]
     # Finality
     justification_bits: Bitvector[JUSTIFICATION_BITS_LENGTH]  # Bit set for every recent justified epoch
     previous_justified_checkpoint: Checkpoint
@@ -201,7 +201,7 @@ def eth2_fast_aggregate_verify(pubkeys: Sequence[BLSPubkey], message: Bytes32, s
 #### `flags_and_numerators`
 
 ```python
-def get_flags_and_numerators() -> Sequence[Tuple[ValidatorFlags, int]]:
+def get_flags_and_numerators() -> Sequence[Tuple[ValidatorFlag, int]]:
     return (
         (TIMELY_HEAD_FLAG, TIMELY_HEAD_NUMERATOR),
         (TIMELY_SOURCE_FLAG, TIMELY_SOURCE_NUMERATOR),
@@ -210,12 +210,12 @@ def get_flags_and_numerators() -> Sequence[Tuple[ValidatorFlags, int]]:
 ```
 
 ```python
-def add_flags(flags: ValidatorFlags, add: ValidatorFlags) -> ValidatorFlags:
+def add_flags(flags: ValidatorFlag, add: ValidatorFlag) -> ValidatorFlag:
     return flags | add
 ```
 
 ```python
-def has_flags(flags: ValidatorFlags, has: ValidatorFlags) -> bool:
+def has_flags(flags: ValidatorFlag, has: ValidatorFlag) -> bool:
     return flags & has == has
 ```
 
@@ -277,7 +277,7 @@ def get_base_reward(state: BeaconState, index: ValidatorIndex) -> Gwei:
 #### `get_unslashed_participating_indices`
 
 ```python
-def get_unslashed_participating_indices(state: BeaconState, flags: ValidatorFlags, epoch: Epoch) -> Set[ValidatorIndex]:
+def get_unslashed_participating_indices(state: BeaconState, flags: ValidatorFlag, epoch: Epoch) -> Set[ValidatorIndex]:
     """
     Retrieve the active validator indices of the given epoch, which are not slashed, and have all of the given flags. 
     """
@@ -297,7 +297,7 @@ def get_unslashed_participating_indices(state: BeaconState, flags: ValidatorFlag
 
 ```python
 def get_flag_deltas(state: BeaconState,
-                    flag: ValidatorFlags,
+                    flag: ValidatorFlag,
                     numerator: uint64) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
     """
     Compute the rewards and penalties associated with a particular duty, by scanning through the participation
@@ -457,8 +457,8 @@ def process_deposit(state: BeaconState, deposit: Deposit) -> None:
         state.validators.append(get_validator_from_deposit(state, deposit))
         state.balances.append(amount)
         # [Added in hf-1] Initialize empty participation flags for new validator
-        state.previous_epoch_participation.append(ValidatorFlags(0))
-        state.current_epoch_participation.append(ValidatorFlags(0))
+        state.previous_epoch_participation.append(ValidatorFlag(0))
+        state.current_epoch_participation.append(ValidatorFlag(0))
     else:
         # Increase balance by deposit amount
         index = ValidatorIndex(validator_pubkeys.index(pubkey))
@@ -597,5 +597,5 @@ def process_participation_flag_updates(state: BeaconState) -> None:
     Call to ``process_participation_flag_updates`` added to ``process_epoch`` in HF1
     """
     state.previous_epoch_participation = state.current_epoch_participation
-    state.current_epoch_participation = [ValidatorFlags(0) for _ in range(len(state.validators))]
+    state.current_epoch_participation = [ValidatorFlag(0) for _ in range(len(state.validators))]
 ```
diff --git a/specs/lightclient/lightclient-fork.md b/specs/lightclient/lightclient-fork.md
index f5f3d1b7b..aa0171b86 100644
--- a/specs/lightclient/lightclient-fork.md
+++ b/specs/lightclient/lightclient-fork.md
@@ -67,8 +67,8 @@ def upgrade_to_lightclient_patch(pre: phase0.BeaconState) -> BeaconState:
         # Slashings
         slashings=pre.slashings,
         # Attestations
-        previous_epoch_participation=[ValidatorFlags(0) for _ in range(len(pre.validators))],
-        current_epoch_participation=[ValidatorFlags(0) for _ in range(len(pre.validators))],
+        previous_epoch_participation=[ValidatorFlag(0) for _ in range(len(pre.validators))],
+        current_epoch_participation=[ValidatorFlag(0) for _ in range(len(pre.validators))],
         # Finality
         justification_bits=pre.justification_bits,
         previous_justified_checkpoint=pre.previous_justified_checkpoint,
diff --git a/tests/core/pyspec/eth2spec/test/helpers/rewards.py b/tests/core/pyspec/eth2spec/test/helpers/rewards.py
index feaac018b..2499bcffe 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/rewards.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/rewards.py
@@ -314,7 +314,7 @@ def run_test_full_but_partial_participation(spec, state, rng=Random(5522)):
     else:
         for index in range(len(state.validators)):
             if rng.choice([True, False]):
-                state.previous_epoch_participation[index] = spec.ValidatorFlags(0)
+                state.previous_epoch_participation[index] = spec.ValidatorFlag(0)
 
     yield from run_deltas(spec, state)
 
@@ -328,7 +328,7 @@ def run_test_partial(spec, state, fraction_filled):
         state.previous_epoch_attestations = state.previous_epoch_attestations[:num_attestations]
     else:
         for index in range(int(len(state.validators) * fraction_filled)):
-            state.previous_epoch_participation[index] = spec.ValidatorFlags(0)
+            state.previous_epoch_participation[index] = spec.ValidatorFlag(0)
 
     yield from run_deltas(spec, state)
 
@@ -394,7 +394,7 @@ def run_test_some_very_low_effective_balances_that_did_not_attest(spec, state):
     else:
         index = 0
         state.validators[index].effective_balance = 1
-        state.previous_epoch_participation[index] = spec.ValidatorFlags(0)
+        state.previous_epoch_participation[index] = spec.ValidatorFlag(0)
 
     yield from run_deltas(spec, state)
 

From 9313815976803c2e93c8fbb4b2518340c4ce83c7 Mon Sep 17 00:00:00 2001
From: Danny Ryan <dannyjryan@gmail.com>
Date: Thu, 4 Feb 2021 08:47:46 -0700
Subject: [PATCH 9/9] put 'validator' in flags methods

---
 specs/lightclient/beacon-chain.md | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/specs/lightclient/beacon-chain.md b/specs/lightclient/beacon-chain.md
index ff69c1312..e11f50076 100644
--- a/specs/lightclient/beacon-chain.md
+++ b/specs/lightclient/beacon-chain.md
@@ -210,12 +210,12 @@ def get_flags_and_numerators() -> Sequence[Tuple[ValidatorFlag, int]]:
 ```
 
 ```python
-def add_flags(flags: ValidatorFlag, add: ValidatorFlag) -> ValidatorFlag:
+def add_validator_flags(flags: ValidatorFlag, add: ValidatorFlag) -> ValidatorFlag:
     return flags | add
 ```
 
 ```python
-def has_flags(flags: ValidatorFlag, has: ValidatorFlag) -> bool:
+def has_validator_flags(flags: ValidatorFlag, has: ValidatorFlag) -> bool:
     return flags & has == has
 ```
 
@@ -288,7 +288,7 @@ def get_unslashed_participating_indices(state: BeaconState, flags: ValidatorFlag
         epoch_participation = state.previous_epoch_participation
     participating_indices = [
         index for index in get_active_validator_indices(state, epoch)
-        if has_flags(epoch_participation[index], flags)
+        if has_validator_flags(epoch_participation[index], flags)
     ]
     return set(filter(lambda index: not state.validators[index].slashed, participating_indices))
 ```
@@ -410,8 +410,8 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
     proposer_reward_numerator = 0
     for index in get_attesting_indices(state, data, attestation.aggregation_bits):
         for flag, numerator in get_flags_and_numerators():
-            if flag in participation_flags and not has_flags(epoch_participation[index], flag):
-                epoch_participation[index] = add_flags(epoch_participation[index], flag)
+            if flag in participation_flags and not has_validator_flags(epoch_participation[index], flag):
+                epoch_participation[index] = add_validator_flags(epoch_participation[index], flag)
                 proposer_reward_numerator += get_base_reward(state, index) * numerator
 
     # Reward proposer