consensus: remove ClaimValidator and shadow validation infrastructure (gridcoin-community#2880)

BlockRewardRules has been validated as the sole consensus rules
implementation via full mainnet and testnet sync-from-genesis with
zero mismatches. Remove the now-redundant ClaimValidator class (~750
lines), the shadow validation dispatch logic, and associated startup
flags (-consensusrulesimpl, -consensusrulesshadow, -consensusshadowlog).

GridcoinConnectBlock now calls BlockRewardRules::Check() directly.
Update documentation references in block_rewards.h/cpp, tally.cpp,
and design_notes.md to reflect the removal.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jamescowens

src/CMakeLists.txt

@@ -139,7 +139,6 @@ add_library(gridcoin_util STATIC
     gridcoin/crypto/rsaverify.cpp
     gridcoin/claim.cpp
     gridcoin/consensus/block_rewards.cpp
-    gridcoin/consensus/shadow_validator.cpp
     gridcoin/contract/contract.cpp
     gridcoin/contract/message.cpp
     gridcoin/contract/registry.cpp

src/gridcoin/consensus/block_rewards.cpp

@@ -214,8 +214,7 @@ bool BlockRewardRules::ValidateMandatorySidestakeOutputs(
         //
         // Why >= instead of ==:
         //
-        // The >= preserves compatibility with the original ClaimValidator and
-        // provides tolerance for the following edge case:
+        // The >= provides tolerance for the following edge case:
         //
         // Remainder true-up: When mandatory allocations sum to exactly 100%
         // (theoretically possible if MaxMandatorySideStakeTotalAlloc is
@@ -305,7 +304,7 @@ bool BlockRewardRules::ValidateMandatorySidestakeOutputs(
 }
 
 // =============================================================================
-// Full claim validation (replaces ClaimValidator::Check())
+// Full claim validation
 // =============================================================================
 
 bool BlockRewardRules::Check(std::string& error_out) const

src/gridcoin/consensus/block_rewards.h

@@ -52,8 +52,7 @@ class BlockRewardRules
         int block_version,
         int64_t block_time);
 
-    //! Full validation mode — mirrors ClaimValidator constructor.
-    //! Enables Check() for complete claim validation.
+    //! Full validation mode. Enables Check() for complete claim validation.
     BlockRewardRules(
         const CBlock& block,
         const CBlockIndex* pindex,
@@ -62,15 +61,15 @@ class BlockRewardRules
         CAmount fees,
         uint64_t coin_age);
 
-    // --- Full claim validation (replaces ClaimValidator::Check()) ------------
+    // --- Full claim validation ------------------------------------------------
 
     //! Run the complete claim validation suite: research/non-research
     //! branching, reward envelope, MRC outputs, beacon signature, mandatory
     //! sidestakes, and all legacy version-specific checks.
     //!
     //! Returns true if the claim is valid. On failure, error_out contains a
-    //! descriptive error message. Unlike ClaimValidator, this method does NOT
-    //! call CBlock::DoS() — the caller decides on DoS scoring.
+    //! descriptive error message. This method does NOT call CBlock::DoS() —
+    //! the caller decides on DoS scoring.
     //!
     //! Requires the full validation constructor.
     //!

src/gridcoin/consensus/design_notes.md

@@ -33,7 +33,7 @@ consume it.
 
 ### Validation-only logic stays validation-only
 
-The `Check()` path (formerly `ClaimValidator`) is pure validation with no miner
+The `Check()` path (which replaced the former `ClaimValidator` class) is pure validation with no miner
 counterpart. MRC output matching, beacon signature checking, reward envelope
 checks, legacy fallbacks — none of these have a construction dual. Forcing them
 into a unified framework would be over-abstraction for no structural benefit.
@@ -51,7 +51,7 @@ Each step should:
 
 ### Comment preservation
 
-The original `ClaimValidator` contained extensive inline comments explaining
+The original `ClaimValidator` class (now removed) contained extensive inline comments explaining
 *why* validation steps exist — historical context (beaconalt bug, newbie
 snapshot fix), structural invariants (mrc_start_index arithmetic, dust
 elimination ordering relative to shuffle), and subtle distinctions

src/gridcoin/consensus/shadow_validator.cpp

@@ -1107,7 +1107,7 @@ CAmount Tally::AccrualNearLimit(
 CAmount Tally::GetNewbieSuperblockAccrualCorrection(const Cpid& cpid, const SuperblockPtr& current_superblock)
 {
     // This function was moved from the anonymous namespace and private, to public and made static, because it has
-    // to be called from ClaimValidator::CheckResearchReward() directly too. Why?
+    // to be called from BlockRewardRules::Check() directly too. Why?
 
     // The broken original newbie fix was CONDITIONAL. The initialization in Tally::Initialize was broken and would
     // never activate, yet the alternate path through AcceptBlock AddToBlockIndex could actually set the original
@@ -1131,7 +1131,7 @@ CAmount Tally::GetNewbieSuperblockAccrualCorrection(const Cpid& cpid, const Supe
     //    included. This is activated at GetNewbieSnapshotFixHeight(), and will cause this function to be used to apply
     //    the corrections to any CPID's that do not have an accrual account at that height.
     //
-    // 2. It is used in ConnectBlock (the ClaimValidator::CheckResearchReward()) to conditionally apply the accrual
+    // 2. It is used in ConnectBlock (via BlockRewardRules::Check()) to conditionally apply the accrual
     //    correction if the claimed value by the block fails the original CheckReward. If the original computed reward
     //    plus the correction equals the claimed reward, then the block is passed with a warning. This enables any
     //    node to conditionally validate a block that was staked with the accrual correction active, even if the

src/gridcoin/consensus/shadow_validator.h

@@ -17,7 +17,6 @@
 #include "init.h"
 #include "node/ui_interface.h"
 #include "scheduler.h"
-#include "gridcoin/consensus/shadow_validator.h"
 #include "gridcoin/gridcoin.h"
 #include "gridcoin/upgrade.h"
 #include "gridcoin/contract/registry.h"
@@ -176,7 +175,6 @@ void Shutdown(void* parg)
         // This is necessary here to prevent a snapshot download from failing at the cleanup
         // step because of a write lock on accrual/registry.dat.
         GRC::CloseResearcherRegistryFile();
-        GRC::ShutdownShadowValidator();
 
         fs::remove(GetPidFile(gArgs));
         UnregisterWallet(pwalletMain);
@@ -300,15 +298,6 @@ void AddLoggingArgs(ArgsManager& argsman)
     argsman.AddArg("-org=<string>", "Set organization name for identification (default: not set). Required for use "
                                     "on testnet. Do not set this for a wallet on mainnet.",
                    ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-consensusrulesimpl=<old|new>",
-                   "Select consensus rules implementation (default: old; dev only)",
-                   ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-consensusrulesshadow",
-                   "Run shadow implementation alongside authoritative for comparison (default: 0; dev only)",
-                   ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-consensusshadowlog=<path>",
-                   "Write structured JSON-lines shadow comparison log to file (dev only)",
-                   ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
 }
 
 void SetupServerArgs()
@@ -1494,8 +1483,6 @@ bool AppInit2(ThreadHandlerPtr threads)
     // ProcessBlock works properly. If the GRC code fails to initialize, return false (bail).
     if (!GRC::Initialize(threads, pindexBest)) return false;
 
-    GRC::InitShadowValidator();
-
     // ********************************************************* Step 10: import blocks
 
     fs::path pathBootstrap = GetDataDir() / "bootstrap.dat";