From 189891e5923e4cabb3f0ac9bed2678db67a2db95 Mon Sep 17 00:00:00 2001
From: MinglesAI <dev@mingles.ai>
Date: Tue, 31 Mar 2026 10:38:41 +0000
Subject: [PATCH] chore: circuit breaker follow-up cleanup (#30)

- Remove dead CircuitBreakerStatePrefix (prefix 53) from keys.go; the
  implementation already uses string-based CircuitBreakerStateKey with
  KeyPrefix() consistently. Reserved comment added so prefix 53 is not
  reused accidentally.

- Add nil guard in buildSelectionWeightsMap() for eg.GroupData == nil;
  defensive change to prevent a nil-dereference panic in the unlikely
  case EpochGroup is constructed without NewEpochGroup().

- Document zero-value governance param caveat in getCBParams(): setting
  any CB param to 0 via governance silently falls back to compile-time
  defaults. Prefer large values (e.g. CbMissThresholdPct=100) to disable
  threshold enforcement rather than zero.

Addresses reviewer follow-up from issue #30.
---
 inference-chain/x/inference/epochgroup/random.go      | 5 +++++
 inference-chain/x/inference/keeper/circuit_breaker.go | 9 +++++++++
 inference-chain/x/inference/types/keys.go             | 8 +++++---
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/inference-chain/x/inference/epochgroup/random.go b/inference-chain/x/inference/epochgroup/random.go
index 4cbb0d667..f6fe93c2c 100644
--- a/inference-chain/x/inference/epochgroup/random.go
+++ b/inference-chain/x/inference/epochgroup/random.go
@@ -75,7 +75,12 @@ func (eg *EpochGroup) GetRandomMember(
 // PoC voting weights (ValidationWeights[].Weight) and the cosmos-sdk group member
 // weights (used for block production) are NOT modified; this map is used solely by
 // the executor-selection lottery.
+//
+// Returns an empty map if GroupData or ValidationWeights is nil.
 func (eg *EpochGroup) buildSelectionWeightsMap() map[string]int64 {
+	if eg.GroupData == nil {
+		return make(map[string]int64)
+	}
 	weights := make(map[string]int64, len(eg.GroupData.ValidationWeights))
 	for _, vw := range eg.GroupData.ValidationWeights {
 		if vw == nil {
diff --git a/inference-chain/x/inference/keeper/circuit_breaker.go b/inference-chain/x/inference/keeper/circuit_breaker.go
index 03ab13bde..0cf39234c 100644
--- a/inference-chain/x/inference/keeper/circuit_breaker.go
+++ b/inference-chain/x/inference/keeper/circuit_breaker.go
@@ -48,6 +48,15 @@ type cbParams struct {
 
 // getCBParams reads CB parameters from ValidationParams and falls back to Go
 // compile-time defaults for any field that is zero (unset).
+//
+// NOTE: Zero-value governance override caveat — because zero is used as a sentinel
+// for "unset" (triggering the default fallback), it is not possible to set any of
+// these parameters to 0 via a governance proposal. For example, setting
+// CbMissThresholdPct=0 to disable threshold-based exclusion will be silently
+// ignored and the default (DefaultCBMissThresholdPct=25) will be used instead.
+// This is intentional: a threshold of 0 would immediately exclude every node.
+// If disabling the circuit breaker is needed, prefer very large values
+// (e.g. CbMissThresholdPct=100 or CbMinSamples=MaxUint64) rather than zero.
 func (k Keeper) getCBParams(ctx context.Context) cbParams {
 	p := cbParams{
 		MissThresholdPct:      DefaultCBMissThresholdPct,
diff --git a/inference-chain/x/inference/types/keys.go b/inference-chain/x/inference/types/keys.go
index d16ed118b..715312bca 100644
--- a/inference-chain/x/inference/types/keys.go
+++ b/inference-chain/x/inference/types/keys.go
@@ -75,9 +75,11 @@ var (
 	SubnetEscrowCounterPrefix              = collections.NewPrefix(49)
 	SubnetEscrowEpochCountPrefix           = collections.NewPrefix(50)
 	SubnetHostEpochStatsPrefix             = collections.NewPrefix(51)
-	SubnetEscrowsByEpochPrefix             = collections.NewPrefix(52)
-	CircuitBreakerStatePrefix              = collections.NewPrefix(53)
-	ParamsKey                              = []byte("p_inference")
+	SubnetEscrowsByEpochPrefix = collections.NewPrefix(52)
+	// Note: prefix 53 is reserved for circuit breaker state; the implementation uses
+	// the string-based CircuitBreakerStateKey with KeyPrefix() for consistency with
+	// other string-keyed stores in this module. Do not reuse prefix 53.
+	ParamsKey = []byte("p_inference")
 )
 
 func KeyPrefix(p string) []byte {