- Ignores the zip 212 grace period on configured Testnets and Regtest

- Adds debug_validate_without_checkpoints field
- Sets initial peers as an empty set on Regtest

zebra-chain/src/parameters/network.rs

@@ -171,6 +171,14 @@ impl Network {
         Self::new_configured_testnet(testnet::Parameters::new_regtest(activation_heights))
     }
 
+    /// Returns true if the network is Mainnet or the default Testnet, or false otherwise.
+    pub fn is_a_default_network(&self) -> bool {
+        match self {
+            Network::Mainnet => true,
+            Network::Testnet(params) => params.is_default_testnet(),
+        }
+    }
+
     /// Returns true if the network is the default Testnet, or false otherwise.
     pub fn is_default_testnet(&self) -> bool {
         if let Self::Testnet(params) = self {
@@ -198,6 +206,15 @@ impl Network {
         }
     }
 
+    /// Returns true if blocks should be contextually validated without checkpoints on this network
+    pub fn debug_validate_without_checkpoints(&self) -> bool {
+        if let Self::Testnet(params) = self {
+            params.debug_validate_without_checkpoints()
+        } else {
+            false
+        }
+    }
+
     /// Returns the [`NetworkKind`] for this network.
     pub fn kind(&self) -> NetworkKind {
         match self {
@@ -243,6 +260,8 @@ impl Network {
     /// Mandatory checkpoints are a Zebra-specific feature.
     /// If a Zcash consensus rule only applies before the mandatory checkpoint,
     /// Zebra can skip validation of that rule.
+    ///
+    /// ZIP-212 grace period is only applied to default networks.
     pub fn mandatory_checkpoint_height(&self) -> Height {
         // Currently this is after the ZIP-212 grace period.
         //
@@ -252,8 +271,12 @@ impl Network {
             .activation_height(self)
             .expect("Canopy activation height must be present for both networks");
 
-        (canopy_activation + ZIP_212_GRACE_PERIOD_DURATION)
-            .expect("ZIP-212 grace period ends at a valid block height")
+        if self.is_a_default_network() {
+            (canopy_activation + ZIP_212_GRACE_PERIOD_DURATION)
+                .expect("ZIP-212 grace period ends at a valid block height")
+        } else {
+            canopy_activation
+        }
     }
 
     /// Return the network name as defined in

zebra-chain/src/parameters/network/testnet.rs

@@ -73,6 +73,9 @@ pub struct ParametersBuilder {
     hrp_sapling_payment_address: String,
     /// A flag for disabling proof-of-work checks when Zebra is validating blocks
     disable_pow: bool,
+    /// A flag for allowing Zebra to try contextually validating the first queued block
+    /// for a given height below the mandatory checkpoint height.
+    debug_validate_without_checkpoints: bool,
 }
 
 impl Default for ParametersBuilder {
@@ -94,6 +97,7 @@ impl Default for ParametersBuilder {
                 .parse()
                 .expect("hard-coded hash parses"),
             disable_pow: false,
+            debug_validate_without_checkpoints: false,
         }
     }
 }
@@ -240,6 +244,15 @@ impl ParametersBuilder {
         self
     }
 
+    /// Sets the `debug_validate_without_checkpoints` flag to be used in the [`Parameters`] being built.
+    pub fn with_debug_validate_without_checkpoints(
+        mut self,
+        debug_validate_without_checkpoints: bool,
+    ) -> Self {
+        self.debug_validate_without_checkpoints = debug_validate_without_checkpoints;
+        self
+    }
+
     /// Converts the builder to a [`Parameters`] struct
     pub fn finish(self) -> Parameters {
         let Self {
@@ -250,6 +263,7 @@ impl ParametersBuilder {
             hrp_sapling_extended_full_viewing_key,
             hrp_sapling_payment_address,
             disable_pow,
+            debug_validate_without_checkpoints,
         } = self;
         Parameters {
             network_name,
@@ -259,6 +273,7 @@ impl ParametersBuilder {
             hrp_sapling_extended_full_viewing_key,
             hrp_sapling_payment_address,
             disable_pow,
+            debug_validate_without_checkpoints,
         }
     }
 
@@ -289,6 +304,9 @@ pub struct Parameters {
     hrp_sapling_payment_address: String,
     /// A flag for disabling proof-of-work checks when Zebra is validating blocks
     disable_pow: bool,
+    /// A flag for allowing Zebra to try contextually validating the first queued block
+    /// for a given height below the mandatory checkpoint height.
+    debug_validate_without_checkpoints: bool,
 }
 
 impl Default for Parameters {
@@ -316,6 +334,7 @@ impl Parameters {
             ..Self::build()
                 .with_genesis_hash(REGTEST_GENESIS_HASH)
                 .with_disable_pow(true)
+                .with_debug_validate_without_checkpoints(true)
                 .with_sapling_hrps(
                     zp_constants::regtest::HRP_SAPLING_EXTENDED_SPENDING_KEY,
                     zp_constants::regtest::HRP_SAPLING_EXTENDED_FULL_VIEWING_KEY,
@@ -344,6 +363,7 @@ impl Parameters {
             hrp_sapling_extended_full_viewing_key,
             hrp_sapling_payment_address,
             disable_pow,
+            debug_validate_without_checkpoints,
         } = Self::new_regtest(ConfiguredActivationHeights::default());
 
         self.network_name == network_name
@@ -352,6 +372,7 @@ impl Parameters {
             && self.hrp_sapling_extended_full_viewing_key == hrp_sapling_extended_full_viewing_key
             && self.hrp_sapling_payment_address == hrp_sapling_payment_address
             && self.disable_pow == disable_pow
+            && self.debug_validate_without_checkpoints == debug_validate_without_checkpoints
     }
 
     /// Returns the network name
@@ -388,4 +409,9 @@ impl Parameters {
     pub fn disable_pow(&self) -> bool {
         self.disable_pow
     }
+
+    /// Returns true if blocks should be contextually validated without checkpoints on this network
+    pub fn debug_validate_without_checkpoints(&self) -> bool {
+        self.debug_validate_without_checkpoints
+    }
 }

zebra-consensus/src/checkpoint.rs

@@ -777,6 +777,19 @@ where
                     .hash(height)
                     .expect("every checkpoint height must have a hash"),
             ),
+            // Contextually validate and commit the first queued block for a height below the mandatory checkpoint height if
+            // `debug_validate_without_checkpoints` is true for this network.
+            WaitingForBlocks if self.network.debug_validate_without_checkpoints() => {
+                if let Some((height, hash)) = self
+                    .queued
+                    .first_key_value()
+                    .and_then(|(h, blocks)| blocks.first().map(|block| (*h, block.block.hash)))
+                {
+                    (height, hash)
+                } else {
+                    return;
+                }
+            }
             WaitingForBlocks => {
                 return;
             }

zebra-consensus/src/router.rs

@@ -369,9 +369,13 @@ pub fn init_checkpoint_list(config: Config, network: &Network) -> (CheckpointLis
 
     let max_checkpoint_height = if config.checkpoint_sync {
         list.max_height()
-    } else {
+    } else if network.is_a_default_network() {
         list.min_height_in_range(network.mandatory_checkpoint_height()..)
             .expect("hardcoded checkpoint list extends past canopy activation")
+    } else {
+        // Allow for validating blocks below mandatory checkpoint height on configured Testnets and Regtest without
+        // actually checking the checkpoints if checkpoint sync is disabled.
+        network.mandatory_checkpoint_height()
     };
 
     (list, max_checkpoint_height)

zebra-network/src/config.rs

@@ -672,8 +672,8 @@ impl<'de> Deserialize<'de> for Config {
             network: network_kind,
             testnet_parameters,
             regtest_activation_heights,
-            initial_mainnet_peers,
-            initial_testnet_peers,
+            mut initial_mainnet_peers,
+            mut initial_testnet_peers,
             cache_dir,
             peerset_initial_target_size,
             crawl_new_peer_interval,
@@ -700,7 +700,11 @@ impl<'de> Deserialize<'de> for Config {
         let network = match (network_kind, testnet_parameters) {
             (NetworkKind::Mainnet, _) => Network::Mainnet,
             (NetworkKind::Testnet, None) => Network::new_default_testnet(),
-            (NetworkKind::Regtest, _) => Network::new_regtest(regtest_activation_heights),
+            (NetworkKind::Regtest, _) => {
+                initial_mainnet_peers = Default::default();
+                initial_testnet_peers = Default::default();
+                Network::new_regtest(regtest_activation_heights)
+            }
             (
                 NetworkKind::Testnet,
                 Some(DTestnetParameters {