diff --git a/packages/imhotep-solver/src/engine.ts b/packages/imhotep-solver/src/engine.ts
index ff6e69d..87711f9 100644
--- a/packages/imhotep-solver/src/engine.ts
+++ b/packages/imhotep-solver/src/engine.ts
@@ -72,100 +72,119 @@ export interface EvaluationOutput {
 }
 
 /**
- * Register all built-in clause evaluators with the global registry.
- * Call this once before invoking evaluate() if you want the default set.
+ * Populate a ClauseRegistry with all built-in clause evaluators (idempotent).
  */
-export function registerDefaultClauses(): void {
-  registerClause({
+export function populateDefaultClauses(registry: ClauseRegistry): void {
+  const SENTINEL = '__imhotep_clause_defaults__'
+  if (registry.getEvaluator(SENTINEL)) return
+  registry.register({
+    clauseKind: SENTINEL,
+    version: 1,
+    requiredFacts: [],
+    evaluate: () => ({ clauseId: '', status: 'pass' as const, truth: 'determinate' as const }),
+  })
+  registry.register({
     clauseKind: 'relation.leftOf',
     version: 1,
     requiredFacts: ['subject.primaryBox', 'reference.primaryBox'],
     evaluate: evaluateLeftOf,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'relation.rightOf',
     version: 1,
     requiredFacts: ['subject.primaryBox', 'reference.primaryBox'],
     evaluate: evaluateRightOf,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'relation.above',
     version: 1,
     requiredFacts: ['subject.primaryBox', 'reference.primaryBox'],
     evaluate: evaluateAbove,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'relation.below',
     version: 1,
     requiredFacts: ['subject.primaryBox', 'reference.primaryBox'],
     evaluate: evaluateBelow,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'relation.overlaps',
     version: 1,
     requiredFacts: ['subject.primaryBox', 'reference.primaryBox'],
     evaluate: evaluateOverlaps,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'relation.inside',
     version: 1,
     requiredFacts: ['subject.primaryBox', 'reference.primaryBox'],
     evaluate: evaluateInside,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'alignment.alignedWith',
     version: 1,
     requiredFacts: ['subject.primaryBox', 'reference.primaryBox'],
     evaluate: evaluateAlignedWith,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'alignment.centeredWithin',
     version: 1,
     requiredFacts: ['subject.primaryBox', 'reference.primaryBox'],
     evaluate: evaluateCenteredWithin,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'size.atLeast',
     version: 1,
     requiredFacts: ['subject.primaryBox'],
     evaluate: evaluateAtLeast,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'size.atMost',
     version: 1,
     requiredFacts: ['subject.primaryBox'],
     evaluate: evaluateAtMost,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'size.between',
     version: 1,
     requiredFacts: ['subject.primaryBox'],
     evaluate: evaluateBetween,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'size.aspectRatio',
     version: 1,
     requiredFacts: ['subject.primaryBox'],
     evaluate: evaluateAspectRatio,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'topology.clippedBy',
     version: 1,
     requiredFacts: ['subject.clipChain', 'reference.clipChain'],
     evaluate: evaluateClippedBy,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'topology.attachedToScrollContainer',
     version: 1,
     requiredFacts: ['topology.scrollContainerOf'],
     evaluate: evaluateAttachedToScrollContainer,
-  });
-  registerClause({
+  })
+  registry.register({
     clauseKind: 'topology.inStackingContext',
     version: 1,
     requiredFacts: ['topology.stackingContextOf'],
     evaluate: evaluateInStackingContext,
-  });
+  })
+}
+
+/** Create a fresh ClauseRegistry with all built-in clause evaluators pre-registered. */
+export function createDefaultClauseRegistry(): ClauseRegistry {
+  const registry = new ClauseRegistry()
+  populateDefaultClauses(registry)
+  return registry
+}
+
+/** @deprecated Use createDefaultClauseRegistry() or explicit ClauseRegistry injection. */
+export function registerDefaultClauses(): void {
+  populateDefaultClauses(globalClauseRegistry)
 }
 
 /**
@@ -176,7 +195,7 @@ export function evaluate(
   clauses: ClauseDescriptor[],
   options: EvaluationOptions = {},
 ): EvaluationOutput {
-  const registry = options.registry ?? globalClauseRegistry;
+  const registry = options.registry ?? createDefaultClauseRegistry();
   // Reset per-evaluation transform caches so visual rects are recomputed
   // once per subject per evaluation batch.
   clearEvaluationCache(world);
diff --git a/packages/imhotep-solver/src/index.ts b/packages/imhotep-solver/src/index.ts
index 2a00fc2..5f288a6 100644
--- a/packages/imhotep-solver/src/index.ts
+++ b/packages/imhotep-solver/src/index.ts
@@ -66,6 +66,8 @@ export {
   evaluate,
   collectRequiredFacts,
   registerDefaultClauses,
+  createDefaultClauseRegistry,
+  populateDefaultClauses,
   type EvaluationOptions,
   type EvaluationOutput,
 } from './engine.js';
@@ -78,6 +80,8 @@ export {
   getPredicateDescriptor,
   getRequiredFactsForPredicate,
   registerDefaultPredicates,
+  createDefaultPredicateRegistry,
+  populateDefaultPredicates,
   BUILTIN_PREDICATES,
   type PredicateDescriptor,
   type PredicateEvaluator,
diff --git a/packages/imhotep-solver/src/logic-engine.ts b/packages/imhotep-solver/src/logic-engine.ts
index ac4822e..7f1ad6e 100644
--- a/packages/imhotep-solver/src/logic-engine.ts
+++ b/packages/imhotep-solver/src/logic-engine.ts
@@ -37,7 +37,7 @@ import {
   getPredicateEvaluator,
   registerDefaultPredicates,
   PredicateRegistry,
-  globalPredicateRegistry,
+  createDefaultPredicateRegistry,
 } from './predicates.js';
 
 import {
@@ -906,7 +906,7 @@ export function evaluateLogic(input: LogicEngineInput): DeterministicSceneEvalua
     proofs: [],
     proofCounter: 0,
     formulaCounter: 0,
-    predicateRegistry: options.predicateRegistry ?? globalPredicateRegistry,
+    predicateRegistry: options.predicateRegistry ?? createDefaultPredicateRegistry(),
   };
 
   addTrace(state, 'evaluate-logic-start');
diff --git a/packages/imhotep-solver/src/predicates.ts b/packages/imhotep-solver/src/predicates.ts
index 1940233..7b91925 100644
--- a/packages/imhotep-solver/src/predicates.ts
+++ b/packages/imhotep-solver/src/predicates.ts
@@ -1200,45 +1200,56 @@ export const hasGapPredicate: PredicateEvaluator = {
 /** Sentinel registered to detect if defaults were already installed. */
 const DEFAULT_SENTINEL = '__imhotep_defaults_registered__'
 
-export function registerDefaultPredicates(): void {
-  if (globalPredicateRegistry.get(DEFAULT_SENTINEL)) return
-  // Register sentinel first so partial failures don't cause infinite loops.
-  globalPredicateRegistry.register({
+/** Populate a PredicateRegistry with all 33 built-in predicates (idempotent). */
+export function populateDefaultPredicates(registry: PredicateRegistry): void {
+  if (registry.get(DEFAULT_SENTINEL)) return
+  registry.register({
     descriptor: { name: DEFAULT_SENTINEL, arity: 0, domains: [], requiredFacts: [] },
     evaluateTuple: () => ({ truth: 'indeterminate' }),
   })
-  registerPredicate(widthPredicate);
-  registerPredicate(heightPredicate);
-  registerPredicate(abovePredicate);
-  registerPredicate(belowPredicate);
-  registerPredicate(leftOfPredicate);
-  registerPredicate(rightOfPredicate);
-  registerPredicate(insidePredicate);
-  registerPredicate(containsPredicate);
-  registerPredicate(overlapsPredicate);
-  registerPredicate(alignedWithPredicate);
-  registerPredicate(centeredWithinPredicate);
-  registerPredicate(atLeastPredicate);
-  registerPredicate(atMostPredicate);
-  registerPredicate(betweenPredicate);
-  registerPredicate(clippedByPredicate);
-  registerPredicate(attachedToScrollContainerPredicate);
-  registerPredicate(escapeClippingChainOfPredicate);
-  registerPredicate(aspectRatioPredicate);
-  registerPredicate(inStackingContextPredicate);
-  registerPredicate(separatedFromPredicate);
-  registerPredicate(leftAlignedWithPredicate);
-  registerPredicate(rightAlignedWithPredicate);
-  registerPredicate(topAlignedWithPredicate);
-  registerPredicate(bottomAlignedWithPredicate);
-  registerPredicate(intersectsPredicate);
-  registerPredicate(touchesPredicate);
-  registerPredicate(hasGapPredicate);
-  registerPredicate(besidePredicate);
-  registerPredicate(nextToPredicate);
-  registerPredicate(adjacentPredicate);
-  registerPredicate(touchingPredicate);
-  registerPredicate(nearPredicate);
-  registerPredicate(underPredicate);
-  registerPredicate(withinPredicate);
+  registry.register(widthPredicate)
+  registry.register(heightPredicate)
+  registry.register(abovePredicate)
+  registry.register(belowPredicate)
+  registry.register(leftOfPredicate)
+  registry.register(rightOfPredicate)
+  registry.register(insidePredicate)
+  registry.register(containsPredicate)
+  registry.register(overlapsPredicate)
+  registry.register(alignedWithPredicate)
+  registry.register(centeredWithinPredicate)
+  registry.register(atLeastPredicate)
+  registry.register(atMostPredicate)
+  registry.register(betweenPredicate)
+  registry.register(clippedByPredicate)
+  registry.register(attachedToScrollContainerPredicate)
+  registry.register(escapeClippingChainOfPredicate)
+  registry.register(aspectRatioPredicate)
+  registry.register(inStackingContextPredicate)
+  registry.register(separatedFromPredicate)
+  registry.register(leftAlignedWithPredicate)
+  registry.register(rightAlignedWithPredicate)
+  registry.register(topAlignedWithPredicate)
+  registry.register(bottomAlignedWithPredicate)
+  registry.register(intersectsPredicate)
+  registry.register(touchesPredicate)
+  registry.register(hasGapPredicate)
+  registry.register(besidePredicate)
+  registry.register(nextToPredicate)
+  registry.register(adjacentPredicate)
+  registry.register(touchingPredicate)
+  registry.register(nearPredicate)
+  registry.register(underPredicate)
+  registry.register(withinPredicate)
+}
+
+/** Create a fresh PredicateRegistry with all 33 built-in predicates pre-registered. */
+export function createDefaultPredicateRegistry(): PredicateRegistry {
+  const registry = new PredicateRegistry()
+  populateDefaultPredicates(registry)
+  return registry
+}
+
+export function registerDefaultPredicates(): void {
+  populateDefaultPredicates(globalPredicateRegistry)
 }
diff --git a/packages/imhotep-solver/src/registry.ts b/packages/imhotep-solver/src/registry.ts
index ebd254f..ab111cb 100644
--- a/packages/imhotep-solver/src/registry.ts
+++ b/packages/imhotep-solver/src/registry.ts
@@ -297,7 +297,7 @@ export class ClauseRegistry {
 /** @deprecated Use explicit ClauseRegistry injection via EvaluationOptions.registry. */
 export const globalClauseRegistry = new ClauseRegistry();
 
-/** Register a clause family so the engine can route evaluation. */
+/** Register a clause family in the global registry. @deprecated Use ClauseRegistry.register directly. */
 export function registerClause(entry: ClauseEntry): void {
   globalClauseRegistry.register(entry);
 }