feat(nns): Reduce maximum dissolve delay to 2 years and clamp all neurons

rs/nns/governance/proto/ic_nns_governance/pb/v1/governance.proto

@@ -1979,6 +1979,16 @@ message LoadCanisterSnapshot {
   bytes snapshot_id = 2;
 }
 
+// Snapshot of a neuron's dissolve state, recorded before clamping to the
+// Mission 70 maximum. Used to restore the original dissolve state if the
+// maximum dissolve delay is ever increased again.
+message NeuronDissolveStateSnapshot {
+  oneof dissolve_state {
+    uint64 dissolve_delay_seconds = 1;
+    uint64 when_dissolved_timestamp_seconds = 2;
+  }
+}
+
 // This represents the whole NNS governance system. It contains all
 // information about the NNS governance system that must be kept
 // across upgrades of the NNS governance system.
@@ -2219,6 +2229,10 @@ message Governance {
   // This prevents the migration from running more than once.
   bool eight_year_gang_bonus_migration_done = 31;
 
+  // Snapshot of each neuron's dissolve state taken while clamping to the Mission 70 maximum
+  // dissolve delay. Enables restoring original dissolve states if the maximum is reversed.
+  map<uint64, NeuronDissolveStateSnapshot> neuron_id_to_pre_clamp_dissolve_state = 32;
+
   reserved 30;
   reserved "first_proposal_id_to_record_voting_history";
 

rs/nns/governance/src/gen/ic_nns_governance.pb.v1.rs

@@ -2955,6 +2955,42 @@ pub struct LoadCanisterSnapshot {
     #[prost(bytes = "vec", tag = "2")]
     pub snapshot_id: ::prost::alloc::vec::Vec<u8>,
 }
+/// Snapshot of a neuron's dissolve state, recorded before clamping to the
+/// Mission 70 maximum. Used to restore the original dissolve state if the
+/// maximum dissolve delay is ever increased again.
+#[derive(
+    candid::CandidType,
+    candid::Deserialize,
+    serde::Serialize,
+    comparable::Comparable,
+    Clone,
+    Copy,
+    PartialEq,
+    ::prost::Message,
+)]
+pub struct NeuronDissolveStateSnapshot {
+    #[prost(oneof = "neuron_dissolve_state_snapshot::DissolveState", tags = "1, 2")]
+    pub dissolve_state: ::core::option::Option<neuron_dissolve_state_snapshot::DissolveState>,
+}
+/// Nested message and enum types in `NeuronDissolveStateSnapshot`.
+pub mod neuron_dissolve_state_snapshot {
+    #[derive(
+        candid::CandidType,
+        candid::Deserialize,
+        serde::Serialize,
+        comparable::Comparable,
+        Clone,
+        Copy,
+        PartialEq,
+        ::prost::Oneof,
+    )]
+    pub enum DissolveState {
+        #[prost(uint64, tag = "1")]
+        DissolveDelaySeconds(u64),
+        #[prost(uint64, tag = "2")]
+        WhenDissolvedTimestampSeconds(u64),
+    }
+}
 /// This represents the whole NNS governance system. It contains all
 /// information about the NNS governance system that must be kept
 /// across upgrades of the NNS governance system.
@@ -3078,6 +3114,11 @@ pub struct Governance {
     /// This prevents the migration from running more than once.
     #[prost(bool, tag = "31")]
     pub eight_year_gang_bonus_migration_done: bool,
+    /// Snapshot of each neuron's dissolve state taken while clamping to the Mission 70 maximum
+    /// dissolve delay. Enables restoring original dissolve states if the maximum is reversed.
+    #[prost(map = "uint64, message", tag = "32")]
+    pub neuron_id_to_pre_clamp_dissolve_state:
+        ::std::collections::HashMap<u64, NeuronDissolveStateSnapshot>,
 }
 /// Nested message and enum types in `Governance`.
 pub mod governance {

rs/nns/governance/src/governance.rs

@@ -13,7 +13,8 @@ use crate::{
         HeapGovernanceData, XdrConversionRate, initialize_governance, reassemble_governance_proto,
         split_governance_proto,
     },
-    is_comprehensive_neuron_list_enabled, is_neuron_follow_restrictions_enabled,
+    is_comprehensive_neuron_list_enabled, is_mission_70_voting_rewards_enabled,
+    is_neuron_follow_restrictions_enabled,
     neuron::{DissolveStateAndAge, Neuron, NeuronBuilder, Visibility},
     neuron_data_validation::{NeuronDataValidationSummary, NeuronDataValidator},
     neuron_store::{
@@ -199,9 +200,6 @@ pub const PROPOSAL_MOTION_TEXT_BYTES_MAX: usize = 10000;
 // The minimum neuron dissolve delay (set when a neuron is first claimed)
 pub const INITIAL_NEURON_DISSOLVE_DELAY: u64 = 7 * ONE_DAY_SECONDS;
 
-// The maximum dissolve delay allowed for a neuron.
-pub const MAX_DISSOLVE_DELAY_SECONDS: u64 = 8 * ONE_YEAR_SECONDS;
-
 // The age of a neuron that saturates the age bonus for the voting power
 // computation.
 pub const MAX_NEURON_AGE_FOR_AGE_BONUS: u64 = 4 * ONE_YEAR_SECONDS;
@@ -286,6 +284,21 @@ pub const MAX_NEURONS_FUND_PARTICIPANTS: u64 = 5_000;
 /// in the same limit.
 const NEURON_RATE_LIMITER_KEY: &str = "ADD_NEURON";
 
+// The maximum dissolve delay allowed for a neuron.
+pub const MAX_DISSOLVE_DELAY_SECONDS_PRE_MISSION_70: u64 = 8 * ONE_YEAR_SECONDS;
+pub const MAX_DISSOLVE_DELAY_SECONDS_POST_MISSION_70: u64 = 2 * ONE_YEAR_SECONDS;
+
+/// Returns the maximum dissolve delay allowed for a neuron. After the flag is enabled, we can
+/// replace `max_dissolve_delay_seconds()` with `MAX_DISSOLVE_DELAY_SECONDS` and set
+/// `MAX_DISSOLVE_DELAY_SECONDS` to `MAX_DISSOLVE_DELAY_SECONDS_POST_MISSION_70`.
+pub fn max_dissolve_delay_seconds() -> u64 {
+    if is_mission_70_voting_rewards_enabled() {
+        MAX_DISSOLVE_DELAY_SECONDS_POST_MISSION_70
+    } else {
+        MAX_DISSOLVE_DELAY_SECONDS_PRE_MISSION_70
+    }
+}
+
 impl GovernanceError {
     pub fn new(error_type: ErrorType) -> Self {
         Self {
@@ -1328,6 +1341,21 @@ impl Governance {
         // A one-time data migration.
         governance.maybe_set_eight_year_gang_bonus_base();
 
+        // Clamp all neuron dissolve delays to the Mission 70 maximum exactly once.
+        // The snapshot serves as the idempotency guard: if it's already populated,
+        // clamping has already run and we must not overwrite the pre-clamp record.
+        if is_mission_70_voting_rewards_enabled()
+            && governance
+                .heap_data
+                .neuron_id_to_pre_clamp_dissolve_state
+                .is_empty()
+        {
+            let now = governance.env.now();
+            governance.heap_data.neuron_id_to_pre_clamp_dissolve_state = governance
+                .neuron_store
+                .clamp_dissolve_delay_for_all_neurons_or_panic(now);
+        }
+
         governance
     }
 
@@ -2965,7 +2993,7 @@ impl Governance {
 
         let dissolve_delay_seconds = std::cmp::min(
             disburse_to_neuron.dissolve_delay_seconds,
-            MAX_DISSOLVE_DELAY_SECONDS,
+            max_dissolve_delay_seconds(),
         );
 
         let dissolve_state_and_age = if dissolve_delay_seconds > 0 {
@@ -3805,7 +3833,7 @@ impl Governance {
                 let nid = self.neuron_store.new_neuron_id(&mut *self.randomness)?;
                 let dissolve_delay_seconds = std::cmp::min(
                     reward_to_neuron.dissolve_delay_seconds,
-                    MAX_DISSOLVE_DELAY_SECONDS,
+                    max_dissolve_delay_seconds(),
                 );
 
                 let dissolve_state_and_age = if dissolve_delay_seconds > 0 {

rs/nns/governance/src/governance/create_neuron.rs

@@ -1,6 +1,6 @@
 use crate::{
     governance::{
-        Governance, INITIAL_NEURON_DISSOLVE_DELAY, LOG_PREFIX, MAX_DISSOLVE_DELAY_SECONDS,
+        Governance, INITIAL_NEURON_DISSOLVE_DELAY, LOG_PREFIX, max_dissolve_delay_seconds,
     },
     neuron::{DissolveStateAndAge, NeuronBuilder},
     pb::v1::{
@@ -73,12 +73,13 @@ impl Governance {
                 ),
             ));
         }
-        if dissolve_delay_seconds > MAX_DISSOLVE_DELAY_SECONDS {
+        if dissolve_delay_seconds > max_dissolve_delay_seconds() {
             return Err(GovernanceError::new_with_message(
                 ErrorType::InvalidCommand,
                 format!(
                     "Dissolve delay {dissolve_delay_seconds} is greater than the maximum \
-            dissolve delay {MAX_DISSOLVE_DELAY_SECONDS}"
+            dissolve delay {}",
+                    max_dissolve_delay_seconds()
                 ),
             ));
         }

rs/nns/governance/src/governance/tests/mod.rs

@@ -3,7 +3,7 @@ use crate::pb::v1::ExecuteNnsFunction;
 use crate::storage::with_voting_history_store;
 use crate::test_utils::MockRandomness;
 use crate::{
-    governance::MAX_DISSOLVE_DELAY_SECONDS,
+    governance::MAX_DISSOLVE_DELAY_SECONDS_PRE_MISSION_70,
     neuron::{DissolveStateAndAge, NeuronBuilder},
     test_utils::{MockEnvironment, StubCMC, StubIcpLedger},
 };
@@ -1735,7 +1735,7 @@ fn test_maybe_set_eight_year_gang_bonus_base() {
     let neuron = NeuronBuilder::new_for_test(
         1,
         DissolveStateAndAge::NotDissolving {
-            dissolve_delay_seconds: MAX_DISSOLVE_DELAY_SECONDS,
+            dissolve_delay_seconds: MAX_DISSOLVE_DELAY_SECONDS_PRE_MISSION_70,
             aging_since_timestamp_seconds: 0,
         },
     )

rs/nns/governance/src/heap_governance_data.rs

@@ -2,8 +2,8 @@ use crate::{
     neuron::Neuron,
     pb::v1::{
         Followees, Governance as GovernanceProto, MonthlyNodeProviderRewards, NetworkEconomics,
-        NeuronStakeTransfer, NodeProvider, ProposalData, RestoreAgingSummary, RewardEvent, Topic,
-        XdrConversionRate as XdrConversionRatePb,
+        NeuronDissolveStateSnapshot, NeuronStakeTransfer, NodeProvider, ProposalData,
+        RestoreAgingSummary, RewardEvent, Topic, XdrConversionRate as XdrConversionRatePb,
         governance::{GovernanceCachedMetrics, NeuronInFlightCommand},
     },
 };
@@ -37,6 +37,7 @@ pub struct HeapGovernanceData {
     pub restore_aging_summary: Option<RestoreAgingSummary>,
     pub topic_of_garbage_collected_proposals: HashMap<u64, Topic>,
     pub eight_year_gang_bonus_migration_done: bool,
+    pub neuron_id_to_pre_clamp_dissolve_state: HashMap<u64, NeuronDissolveStateSnapshot>,
 }
 
 /// Internal representation for `XdrConversionRatePb`.
@@ -207,6 +208,7 @@ pub fn initialize_governance(
         restore_aging_summary,
         topic_of_garbage_collected_proposals: HashMap::new(),
         eight_year_gang_bonus_migration_done: false,
+        neuron_id_to_pre_clamp_dissolve_state: HashMap::new(),
     };
 
     // Finally, return the result.
@@ -247,6 +249,7 @@ pub fn split_governance_proto(
         restore_aging_summary,
         topic_of_garbage_collected_proposals,
         eight_year_gang_bonus_migration_done,
+        neuron_id_to_pre_clamp_dissolve_state,
         rng_seed,
     } = governance_proto;
 
@@ -291,6 +294,7 @@ pub fn split_governance_proto(
                 .map(|(k, v)| (k, Topic::try_from(v).unwrap_or(Topic::Unspecified)))
                 .collect(),
             eight_year_gang_bonus_migration_done,
+            neuron_id_to_pre_clamp_dissolve_state,
         },
         rng_seed,
     )
@@ -329,6 +333,7 @@ pub fn reassemble_governance_proto(
         restore_aging_summary,
         topic_of_garbage_collected_proposals,
         eight_year_gang_bonus_migration_done,
+        neuron_id_to_pre_clamp_dissolve_state,
     } = heap_governance_proto;
 
     let neuron_management_voting_period_seconds = Some(neuron_management_voting_period_seconds);
@@ -360,6 +365,7 @@ pub fn reassemble_governance_proto(
             .map(|(k, v)| (k, v as i32))
             .collect(),
         eight_year_gang_bonus_migration_done,
+        neuron_id_to_pre_clamp_dissolve_state,
         rng_seed: rng_seed.map(|seed| seed.to_vec()),
     }
 }
@@ -368,6 +374,7 @@ pub fn reassemble_governance_proto(
 mod tests {
     use super::*;
 
+    use crate::governance::MAX_DISSOLVE_DELAY_SECONDS_PRE_MISSION_70;
     use crate::pb::v1::ProposalData;
 
     use maplit::{btreemap, hashmap};
@@ -400,6 +407,15 @@ mod tests {
             restore_aging_summary: None,
             topic_of_garbage_collected_proposals: hashmap! { 1 => Topic::Unspecified as i32 },
             eight_year_gang_bonus_migration_done: true,
+            neuron_id_to_pre_clamp_dissolve_state: hashmap! {
+                1 => NeuronDissolveStateSnapshot {
+                    dissolve_state: Some(
+                        crate::pb::v1::neuron_dissolve_state_snapshot::DissolveState::DissolveDelaySeconds(
+                            MAX_DISSOLVE_DELAY_SECONDS_PRE_MISSION_70,
+                        ),
+                    ),
+                },
+            },
             rng_seed: Some(vec![1_u8; 32]),
         }
     }