chore: sync lockfile to core ^1.0.8 for CI publish

BEHAVES AS transitive now emits bounded multi_hop configs (direct checks and
evidence references), fixing a silent no-op. NOT builds keep _subjectAsObject
scoping so unary predicates negate the right node, and value-typed evidence
objects gate by exact edge value. Recompiling a scope uninstalls its stale
relation configs (compileMultiple coexistence preserved). Sources become
injectable relations honored by requiredFacts with a within-X recency gate.
Duplicate definition fields and three common declaration mistakes (within on a
fact, two BEHAVES clauses, limit on a non-pattern body) now produce targeted
errors. Provider edges referencing unknown nodes are warned and dropped.

package-lock.json

@@ -1,15 +1,15 @@
 {
   "name": "@arbiter/evidence-dsl",
-  "version": "1.6.0",
+  "version": "1.12.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@arbiter/evidence-dsl",
-      "version": "1.6.0",
+      "version": "1.12.1",
       "license": "ISC",
       "dependencies": {
-        "@arbiter/core": "^1.0.4"
+        "@arbiter/core": "^1.0.8"
       },
       "devDependencies": {
         "@rigor/core": "^3.1.0",
@@ -17,9 +17,9 @@
       }
     },
     "node_modules/@arbiter/core": {
-      "version": "1.0.4",
-      "resolved": "https://hub.kl1.tenere.ai/api/packages/Arbiter/npm/%40arbiter%2Fcore/-/1.0.4/core-1.0.4.tgz",
-      "integrity": "sha512-1zXy3mZACjwELptsV8QpYvZJmMU7BhUQ4FsKNfp3/oJDwjfMqAImcAF3mJ+HNZpQnLQXScmELTwow5VduvN27g==",
+      "version": "1.0.8",
+      "resolved": "https://hub.kl1.tenere.ai/api/packages/Arbiter/npm/%40arbiter%2Fcore/-/1.0.8/core-1.0.8.tgz",
+      "integrity": "sha512-x/nWymJca0AHoUaLrq09ENeiPBplaCcuQbX1zHKVUk1fYoYVfW9ZmmrApoKPsK58WkcPwBWo1cB6VSrGk9//WA==",
       "license": "ISC",
       "dependencies": {
         "@tenere/pltc-core": "^0.6.3",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@arbiter/evidence-dsl",
-  "version": "1.8.0",
+  "version": "1.12.1",
   "description": "Evidence DSL v2 compiler: translates the natural Evidence DSL (ADR-000) into @arbiter/core relation configurations.",
   "license": "ISC",
   "type": "module",
@@ -24,7 +24,7 @@
     "generate:parser": "node scripts/generate-parser.js"
   },
   "dependencies": {
-    "@arbiter/core": "^1.0.4"
+    "@arbiter/core": "^1.0.8"
   },
   "devDependencies": {
     "@rigor/core": "^3.1.0",

src/DSLCompiler.js

@@ -7,10 +7,10 @@ import { validateDslText } from './validation/DSLValidation.js';
  * Compiles DSL text into rule configurations for the zanzibar-graph system
  */
 export class DSLCompiler {
-  constructor(arbiter) {
+  constructor(arbiter, options = {}) {
     this.arbiter = arbiter;
     this.parser = parse;
-    this.generator = new RuleGenerator(arbiter);
+    this.generator = new RuleGenerator(arbiter, options);
     this.compiledPrograms = new Map();
   }
 
@@ -39,13 +39,15 @@ export class DSLCompiler {
       const programNode = {
         definitions: program.body.filter(s => s.type === 'Definition'),
         facts: program.body.filter(s => s.type === 'Fact'),
+        sources: program.body.filter(s => s.type === 'Source'),
         evidence: program.body.filter(s => s.type === 'Evidence'),
         measures: program.body.filter(s => s.type === 'Measure'),
         validate: () => ({ isValid: true, errors: [], warnings: [] })
       };
 
-      // Generate rules from AST
-      const generationResult = this.generator.generateRules(programNode);
+      // Generate rules from AST (scoped to the program name so recompiling a
+      // scope revokes its stale relations without touching other scopes).
+      const generationResult = this.generator.generateRules(programNode, programName);
       
       if (!generationResult.success) {
         return {

src/generator/RuleGenerator.js

@@ -5,12 +5,22 @@ import { ProgramNode, DefinitionNode, FactNode, EvidenceNode, MeasureNode, Direc
  * Generates rule configurations that interface with the existing rule system
  */
 export class RuleGenerator {
-  constructor(arbiter) {
+  constructor(arbiter, options = {}) {
     this.arbiter = arbiter;
     this.generatedRules = new Map();
     this.errors = [];
     this.dependencyIndex = new Map();
     this.evidenceNames = new Set();
+    // Relation names this generator has installed on the arbiter, tracked PER
+    // PROGRAM SCOPE (the compile() program name). Recompiling the same scope
+    // uninstalls relations that scope previously declared but no longer does —
+    // otherwise a revoked evidence/fact keeps its config and still grants
+    // (stale-permission leak). Relations from OTHER scopes (compileMultiple
+    // coexistence) are never touched.
+    this._installedByScope = new Map();
+    this._currentScope = 'default';
+    // Default depth for bounded self-recursion when the DSL `limit N` is absent.
+    this.maxRecursionDepth = options.maxRecursionDepth ?? 3;
   }
 
   /**
@@ -18,10 +28,25 @@ export class RuleGenerator {
    * @param {ProgramNode} program - AST program to generate rules from
    * @returns {Object} Generation result with success status and errors
    */
-  generateRules(program) {
+  generateRules(program, scopeName = 'default') {
     this.errors = [];
+    this._currentScope = scopeName;
+    this.program = program;
     this.generatedRules.clear();
     this.dependencyIndex.clear();
+    // Facts declared `BEHAVES AS transitive` are resolved as bounded transitive
+    // closure (multi_hop) everywhere they are referenced — both the fact's own
+    // config and any direct rule that references the fact. Without this the
+    // declaration parses but grants only direct edges (silent no-op). Value is
+    // the closure depth (the fact's `limit N`, or the recursion default).
+    this.transitiveFacts = new Map();
+    for (const fact of program.facts || []) {
+      const behavior = fact && fact.behavior;
+      if (behavior && (behavior.behavior === 'transitive' || behavior === 'transitive')) {
+        const depth = (fact.limit && typeof fact.limit === 'object' ? fact.limit.value : fact.limit) ?? this.maxRecursionDepth;
+        this.transitiveFacts.set(fact.name, depth);
+      }
+    }
 
     try {
       // Generate rules for each evidence definition
@@ -39,6 +64,14 @@ export class RuleGenerator {
         this.generateFactConfig(fact);
       });
 
+      // Generate source relation configs (injectable, recency-gated proofs).
+      // Without a config a source referenced by an evidence would never
+      // resolve — the reference would lower to a config-less direct rule that
+      // grants nothing.
+      (program.sources || []).forEach(source => {
+        this.generateSourceConfig(source);
+      });
+
       // Resolve evidence composition: a rule that references another derived
       // evidence (WHEN can_read(user, doc) where can_read is an evidence) is
       // lowered in place to that evidence's own config — compile-time inlining
@@ -107,9 +140,13 @@ export class RuleGenerator {
     const paramNames = params.map(p => p.name);
     const paramTypes = params.map(p => p.type);
 
-    this.generatedRules.set(name, {
-      type: 'direct',
-      relation: name,
+    // BEHAVES AS transitive: the fact resolves to bounded transitive closure.
+    // A multi_hop config walks the relation's edges up to maxDepth (the fact's
+    // `limit N`, or the recursion default), so a direct check on the fact —
+    // and any evidence that references it — follows multi-hop paths instead of
+    // only direct edges.
+    const transitiveDepth = this.transitiveFacts.get(name);
+    const base = {
       isFactRelation: true,
       requiresInjection: true,
       arity: paramTypes.length,
@@ -121,6 +158,39 @@ export class RuleGenerator {
           typeof p === 'string' ? [p, true] : Array.isArray(p) ? p : [p, true]
         )
       )
+    };
+
+    this.generatedRules.set(name, transitiveDepth !== undefined
+      ? {
+          type: 'multi_hop',
+          relation: name,
+          maxDepth: transitiveDepth,
+          pathAggregation: 'max',
+          reverse: false,
+          fallbackToBasicPaths: true,
+          collectValues: false,
+          ...base
+        }
+      : {
+          type: 'direct',
+          relation: name,
+          ...base
+        });
+  }
+
+  generateSourceConfig(source) {
+    const name = source.name;
+    const params = source.params || [];
+    const withinMs = source.within ? this._durationToMs(source.within) : null;
+    this.generatedRules.set(name, {
+      type: 'direct',
+      relation: name,
+      isSourceRelation: true,
+      requiresInjection: true,
+      arity: params.length,
+      paramTypes: params.map(p => p.paramType),
+      paramNames: params.map(p => p.name),
+      ...(withinMs !== null ? { withinMs } : {})
     });
   }
 
@@ -296,7 +366,7 @@ export class RuleGenerator {
       case 'PredicateCall':
         return this.buildPredicateRule(statement, evidence);
       case 'UnaryExpression':
-        return this.buildUnaryRule(statement);
+        return this.buildUnaryRule(statement, evidence);
       case 'BinaryExpression':
         // Top-level comparator — emit a relational_comparator rule. RF-24 closure.
         return this.buildRuleFromExpressionNode(statement, evidence);
@@ -315,15 +385,19 @@ export class RuleGenerator {
   /**
    * Build rule for unary expression (NOT)
    * @param {Object} expression - Unary expression
+   * @param {Object} evidence - Evidence definition (threaded through so a
+   *   unary inner predicate like NOT banned(user) keeps its _subjectAsObject
+   *   rewrite; without it the unary fact would be checked on the evidence's
+   *   OBJECT node instead of the subject, silently negating the wrong fact).
    * @returns {Object|null} Rule configuration or null
    */
-  buildUnaryRule(expression) {
+  buildUnaryRule(expression, evidence) {
     if (expression.operator !== 'NOT') {
       this.errors.push(`Unsupported unary operator: ${expression.operator}`);
       return null;
     }
 
-    const innerRule = this.buildRuleFromExpression(expression.operand);
+    const innerRule = this.buildRuleFromExpression(expression.operand, evidence);
     if (!innerRule) {
       return null;
     }
@@ -480,6 +554,12 @@ export class RuleGenerator {
     const predicate = directEvidence.predicate;
     const relation = predicate.name;
 
+    // A reference to a `BEHAVES AS transitive` fact resolves to closure.
+    const transitiveDepth = this.transitiveFacts.get(relation);
+    if (transitiveDepth !== undefined) {
+      return this._buildTransitiveRule(relation, transitiveDepth, predicate.arguments || [], evidence);
+    }
+
     const rule = {
       type: 'direct',
       relation: relation,
@@ -503,6 +583,12 @@ export class RuleGenerator {
       }
     }
 
+    // A literal value in the object position (balance(user, 5)) is a VALUE
+    // constraint, not a node key: the rule only grants when the matched edge
+    // carries exactly that value. Without this gate a value-carrying fact
+    // would match ANY edge regardless of its amount (silent over-grant).
+    this._applyExpectedValue(rule, args);
+
     return rule;
   }
 
@@ -629,7 +715,8 @@ export class RuleGenerator {
       type: 'chain',
       steps,
       aggregator: 'max',
-      collectValues: true
+      collectValues: true,
+      maxDepth: patternMatch.limit || null
     };
   }
 
@@ -670,7 +757,10 @@ export class RuleGenerator {
       type: 'chain',
       steps,
       aggregator: 'max',
-      collectValues: true
+      collectValues: true,
+      // Carry the pattern's `limit N` as a max depth so a self-referential
+      // chain step can be unrolled into bounded transitive closure.
+      maxDepth: patternMatch.limit || null
     };
   }
 
@@ -941,7 +1031,7 @@ export class RuleGenerator {
     } else if (expression.type === 'PredicateCall') {
       return this.buildPredicateRule(expression, evidence);
     } else if (expression.type === 'UnaryExpression') {
-      return this.buildUnaryRule(expression);
+      return this.buildUnaryRule(expression, evidence);
     } else if (expression.type === 'BinaryExpression') {
       return this.buildRuleFromExpressionNode(expression, evidence);
     }
@@ -956,6 +1046,12 @@ export class RuleGenerator {
    * @returns {Object|null} Rule configuration or null
    */
   buildDirectRuleFromPredicate(predicate, evidence) {
+    // A reference to a `BEHAVES AS transitive` fact resolves to closure.
+    const transitiveDepth = this.transitiveFacts.get(predicate.name);
+    if (transitiveDepth !== undefined) {
+      return this._buildTransitiveRule(predicate.name, transitiveDepth, predicate.args || [], evidence);
+    }
+
     const rule = {
       type: 'direct',
       relation: predicate.name,
@@ -969,6 +1065,58 @@ export class RuleGenerator {
       rule._subjectAsObject = true;
     }
 
+    // Value constraint: a literal in the object position (balance(user, 5)).
+    this._applyExpectedValue(rule, predicate.args || []);
+
+    return rule;
+  }
+
+  /**
+   * Annotate a direct rule with `expectedValue` when its object-position
+   * argument is a literal. The engine only grants the rule if the matched
+   * edge's `value` field equals this literal — without the gate a
+   * value-carrying fact would match any edge of the same relation, silently
+   * over-granting (e.g. balance(user, 5) matching a value-3 edge).
+   */
+  _applyExpectedValue(rule, args) {
+    if (rule && args && args.length >= 2) {
+      const objectArg = args[1];
+      if (objectArg && objectArg.type === 'Literal' && objectArg.value !== undefined) {
+        rule.expectedValue = objectArg.value;
+      }
+    }
+    return rule;
+  }
+
+  /**
+   * Build a bounded transitive-closure rule for a `BEHAVES AS transitive`
+   * fact reference. Applies the same subject/object rewrite flags as the
+   * direct-rule builders so a unary or object-var reference still targets the
+   * correct nodes.
+   */
+  _buildTransitiveRule(relation, maxDepth, args, evidence) {
+    const rule = {
+      type: 'multi_hop',
+      relation: relation,
+      maxDepth: maxDepth,
+      pathAggregation: 'max',
+      reverse: false,
+      fallbackToBasicPaths: true,
+      collectValues: false
+    };
+
+    const evidenceParams = (evidence && evidence.params) || [];
+    const objectVar = evidenceParams[1] && evidenceParams[1].name;
+    const argName = a => a && (a.name !== undefined ? a.name : a.value);
+    if (objectVar !== undefined) {
+      const hasObjectArg = args.some(a => a && a.type === 'Variable' && a.name === objectVar);
+      if (args.length === 1 && argName(args[0]) === objectVar) {
+        rule._subjectIsObject = true;
+      } else if (!hasObjectArg) {
+        rule._subjectAsObject = true;
+      }
+    }
+
     return rule;
   }
 
@@ -990,13 +1138,113 @@ export class RuleGenerator {
   resolveEvidenceReferences() {
     for (const name of this.evidenceNames) {
       if (!this.generatedRules.has(name)) continue;
+      let config = this.generatedRules.get(name);
+      // Bounded self-recursion (transitive closure): an evidence whose config
+      // contains a chain step referencing ITSELF is unrolled into a union of
+      // bounded paths — base, hop+base, hop²+base, …, hop^N+base — where `hop`
+      // is the recursive chain's steps before the self-reference and the depth
+      // N comes from the pattern's `limit N` (or the compiler default).
+      const selfRef = this._findSelfReference(config, name);
+      if (selfRef) {
+        const depth = selfRef.limit ?? this.maxRecursionDepth;
+        const unrolled = this._unrollRecursiveEvidence(name, config, selfRef.hop, depth);
+        if (unrolled) {
+          config = unrolled;
+          this.generatedRules.set(name, config);
+        }
+      }
       const stack = new Set([name]);
-      const resolved = this._resolveRule(this.generatedRules.get(name), stack);
+      const resolved = this._resolveRule(config, stack);
       this.generatedRules.set(name, resolved);
       this._annotateDependencies(name, resolved);
     }
   }
 
+  /**
+   * Find the first chain step within `config` that references `name` (a
+   * self-reference). Returns { hop, limit } where hop is the chain's steps
+   * before the self-reference and limit is the chain's declared max depth.
+   * Returns null when there is no self-reference.
+   */
+  _findSelfReference(config, name) {
+    let found = null;
+    const walk = (rule) => {
+      if (!rule || typeof rule !== 'object' || found) return;
+      if (rule.type === 'chain' && Array.isArray(rule.steps)) {
+        const idx = rule.steps.findIndex(s => (typeof s === 'string' ? s : s && s.relation) === name);
+        if (idx >= 0) {
+          const lim = rule.maxDepth;
+          const limit = lim && typeof lim === 'object' ? lim.value : lim;
+          found = { hop: rule.steps.slice(0, idx), limit: Number.isFinite(limit) ? limit : null };
+          return;
+        }
+      }
+      for (const key of ['union', 'intersection', 'exclusion', 'never', 'always', 'requires', 'when', 'unless']) {
+        const node = rule[key];
+        if (!node) continue;
+        if (Array.isArray(node.rules)) for (const c of node.rules) walk(c);
+        if (Array.isArray(node.union?.rules)) for (const c of node.union.rules) walk(c);
+        if (Array.isArray(node.intersection?.rules)) for (const c of node.intersection.rules) walk(c);
+        if (node.direct) walk(node.direct);
+        if (node.rule) walk(node.rule);
+      }
+    };
+    walk(config);
+    return found;
+  }
+
+  /**
+   * Unroll a self-recursive evidence into a bounded transitive closure.
+   * The recursive chain is removed from the config; the remainder is the base.
+   * Result: union([base, hop+base, hop²+base, …, hop^depth+base]) where the
+   * base is verified as a condition step at each path's terminal node.
+   */
+  _unrollRecursiveEvidence(name, config, hop, depth) {
+    if (hop.length === 0) {
+      this.errors.push(`Recursive evidence '${name}' has an empty recursion hop (no steps before the self-reference).`);
+      return null;
+    }
+    const base = this._extractBase(config, name);
+    if (!base) {
+      this.errors.push(`Recursive evidence '${name}' has no base case — pure recursion cannot grant. Add a non-recursive statement.`);
+      return null;
+    }
+    const rules = [this._deepCloneRule(base)];
+    for (let d = 1; d <= depth; d++) {
+      const steps = [];
+      for (let h = 0; h < d; h++) steps.push(...hop.map(s => this._deepCloneRule(s)));
+      steps.push({ rule: this._deepCloneRule(base), conditionStep: true });
+      rules.push({ type: 'chain', steps, aggregator: 'max', collectValues: true });
+    }
+    return { type: 'logical', union: { rules, aggregator: 'max' } };
+  }
+
+  /**
+   * Remove the recursive chain (the chain containing a self-reference) from an
+   * evidence config and return the remainder as the base case. Returns null if
+   * there is no base (pure recursion).
+   */
+  _extractBase(config, name) {
+    if (config.type === 'chain') {
+      const hasSelf = (config.steps || []).some(s => (typeof s === 'string' ? s : s && s.relation) === name);
+      return hasSelf ? null : this._deepCloneRule(config);
+    }
+    if (config.type === 'logical' && config.intersection) {
+      const remaining = (config.intersection.rules || []).filter(r => {
+        // keep rules that are not (or do not contain) the recursive chain
+        return !this._containsSelfReference(r, name);
+      });
+      if (remaining.length === 0) return null;
+      if (remaining.length === 1) return this._deepCloneRule(remaining[0]);
+      return { type: 'logical', intersection: { rules: remaining.map(r => this._deepCloneRule(r)), aggregator: config.intersection.aggregator || 'min' } };
+    }
+    return this._containsSelfReference(config, name) ? null : this._deepCloneRule(config);
+  }
+
+  _containsSelfReference(rule, name) {
+    return this._findSelfReference(rule, name) !== null;
+  }
+
   /**
    * Recursively rewrite a rule tree, inlining references to derived evidence
    * configs. `stack` holds the evidence names currently being expanded so a
@@ -1111,6 +1359,15 @@ export class RuleGenerator {
             out.push(...this._expandChainSteps(resolved.steps, refStack));
             continue;
           }
+          if (resolved.type === 'relational_comparator' && idx !== steps.length - 1) {
+            // A comparator compares values at (src, candidate) but provides no
+            // candidate set — it cannot enumerate intermediate nodes, so only
+            // a FINAL comparator step (verified at the known object) lowers.
+            this.errors.push(`Chain step '${stepName}' references a comparator evidence at a non-final position. ` +
+              'Comparators can only be the final chain step (the object is known); intermediate positions are not enumerable.');
+            out.push(step);
+            continue;
+          }
           // Condition step: inline the evidence's config as a rule step. As the
           // FINAL step the engine verifies it at (intermediate, object); as an
           // INTERMEDIATE step the engine EXPANDS it from the current node
@@ -1276,6 +1533,13 @@ export class RuleGenerator {
       return this.buildChallengeRule(expression, null);
     }
 
+    // A reference to a `BEHAVES AS transitive` fact resolves to bounded
+    // transitive closure, not a direct edge lookup.
+    const transitiveDepth = this.transitiveFacts.get(predicateName);
+    if (transitiveDepth !== undefined) {
+      return this._buildTransitiveRule(predicateName, transitiveDepth, expression.args || [], evidence);
+    }
+
     const rule = {
       type: 'direct',
       relation: predicateName,
@@ -1303,6 +1567,11 @@ export class RuleGenerator {
       }
     }
 
+    // Value constraint: a literal in the object position (balance(user, 5))
+    // is a VALUE gate, not a node key — the rule only grants when the matched
+    // edge carries exactly that value.
+    this._applyExpectedValue(rule, expression.args || []);
+
     return rule;
   }
 
@@ -1416,6 +1685,19 @@ export class RuleGenerator {
       return;
     }
     
+    // Recompile hygiene (per program scope): relations installed by a previous
+    // compile of THIS scope but absent from the current program are stale —
+    // remove their configs from every cache and index so a revoked relation
+    // stops granting immediately. Relations belonging to other scopes
+    // (compileMultiple coexistence) are left intact.
+    const scope = this._currentScope || 'default';
+    const previously = this._installedByScope.get(scope) || new Set();
+    for (const name of previously) {
+      if (!this.generatedRules.has(name)) {
+        this._uninstallRelation(name);
+      }
+    }
+
     this.generatedRules.forEach((config, relation) => {
       try {
         this.arbiter.setRelationConfig(relation, config);
@@ -1427,6 +1709,33 @@ export class RuleGenerator {
     if (typeof this.arbiter.registerDependencyIndex === 'function') {
       this.arbiter.registerDependencyIndex(this.dependencyIndex);
     }
+
+    this._installedByScope.set(scope, new Set(this.generatedRules.keys()));
+  }
+
+  /**
+   * Remove a relation's config and cached state from the arbiter. Mirrors the
+   * invalidation that setRelationConfig performs, applied to deletion.
+   */
+  _uninstallRelation(name) {
+    const arb = this.arbiter;
+    if (!arb) return;
+    if (arb.relationConfigs && typeof arb.relationConfigs.delete === 'function') {
+      arb.relationConfigs.delete(name);
+    }
+    const analysis = arb.graphManager && arb.graphManager.analysis;
+    if (analysis && analysis.relationConfigs && typeof analysis.relationConfigs.delete === 'function') {
+      analysis.relationConfigs.delete(name);
+    }
+    if (typeof arb._invalidateDirectCheckCache === 'function') {
+      arb._invalidateDirectCheckCache(null, name, null);
+    }
+    if (typeof arb.invalidateRuleResultCacheByRelation === 'function') {
+      arb.invalidateRuleResultCacheByRelation(name);
+    }
+    if (arb.authChecker && typeof arb.authChecker.invalidateRuleCaches === 'function') {
+      arb.authChecker.invalidateRuleCaches(name);
+    }
   }
 
   /**

src/grammar/dsl.peggy

@@ -54,11 +54,14 @@ Definition "A type definition"
     }
 
 Field
-  = name:Identifier _ ":" _ fieldType:Type _ isArray:("[]")? _ behavior:Behavior? _ cache:CacheDirective? {
+  = name:Identifier _ ":" _ fieldType:Type optional:("?")? _ isArray:("[]")? _ behavior:Behavior? _ cache:CacheDirective? {
       return {
         type: "Field",
         name,
         fieldType,
+        // `field: type` is REQUIRED on node insert; `field: type?` is optional.
+        // Presence is enforced by the DSLRuntime when a node is created.
+        required: !optional,
         isArray: !!isArray,
         behavior: behavior || null,
         cache: cache || null
@@ -392,7 +395,7 @@ Boolean "A boolean literal"
   = value:("true" / "false") { return { type: "Literal", value: value === "true" }; }
 
 Duration "A time duration literal"
-  = value:([0-9]+ ("h" / "d" / "w" / "m")) { return { type: "Literal", value: text(), unit: text().slice(-1) }; }
+  = value:([0-9]+ ("s" / "m" / "h" / "d" / "w")) { return { type: "Literal", value: text(), unit: text().slice(-1) }; }
 
 
 // -- Core Tokens & Whitespace --

src/runtime/DSLRuntime.js

@@ -60,6 +60,12 @@ export class DSLRuntime {
     this.clock = typeof options.clock === 'function' ? options.clock : (() => Date.now());
     // Default provider-result TTL in ms (0 disables caching).
     this.defaultProviderCacheTTL = options.policy?.providerCacheTTL ?? options.providerCacheTTL ?? 30_000;
+    // Provider caching is a STORE-RETRIEVAL cache (wall-clock), deliberately
+    // independent of the caller's decision `{ now }` — a provider returns the
+    // store's current data, not a time-travel snapshot. Callers who pin time
+    // or otherwise want fresh retrieval can disable it per-check
+    // (options.cacheProviderResults: false) or globally (policy).
+    this.cacheProviderResults = options.policy?.cacheProviderResults ?? options.cacheProviderResults ?? true;
     // Per-fact overrides (ms). DSL-declared ttl behaviors are indexed here too.
     this.factTTLs = new Map(Object.entries(options.factTTLs || {}));
   }
@@ -97,12 +103,16 @@ export class DSLRuntime {
       fields: [...fields.entries()].map(([fieldName, f]) => ({
         name: fieldName,
         type: f.type,
-        isArray: f.isArray
+        isArray: f.isArray,
+        required: f.required !== false
       }))
     }));
     const facts = [...this.relations.entries()]
       .filter(([, r]) => r.kind === 'fact')
       .map(([name, r]) => ({ name, params: r.params, injectable: r.injectable }));
+    const sources = [...this.relations.entries()]
+      .filter(([, r]) => r.kind === 'source')
+      .map(([name, r]) => ({ name, params: r.params, injectable: true, withinMs: r.withinMs }));
     const evidence = [...this.relations.entries()]
       .filter(([, r]) => r.kind === 'evidence')
       .map(([name, r]) => ({
@@ -110,7 +120,7 @@ export class DSLRuntime {
         params: r.params,
         dependsOn: [...(this.dependsOn.get(name) || [])]
       }));
-    return { types, facts, evidence, providers: this.registeredFacts() };
+    return { types, facts, sources, evidence, providers: this.registeredFacts() };
   }
 
   /** All relation names declared by the program (facts + evidence). */
@@ -126,7 +136,7 @@ export class DSLRuntime {
     for (const def of this.program.definitions || []) {
       const fields = new Map();
       for (const field of def.fields || []) {
-        fields.set(field.name, { type: field.fieldType, isArray: !!field.isArray });
+        fields.set(field.name, { type: field.fieldType, isArray: !!field.isArray, required: field.required !== false });
       }
       this.types.set(def.name, { fields });
     }
@@ -141,6 +151,18 @@ export class DSLRuntime {
       });
     }
 
+    // Sources are injectable, recency-gated proofs: registered as retrievable
+    // relations so a provider can supply them and `within X` gates freshness.
+    for (const src of this.program.sources || []) {
+      this.relations.set(src.name, {
+        kind: 'source',
+        params: (src.params || []).map(p => ({ name: p.name, type: p.paramType, isArray: !!p.isArray })),
+        injectable: true,
+        ttlMs: 0,
+        withinMs: src.within ? this._durationToMs(src.within) : null
+      });
+    }
+
     for (const ev of this.program.evidence || []) {
       this.relations.set(ev.name, {
         kind: 'evidence',
@@ -296,41 +318,87 @@ export class DSLRuntime {
     const b = behavior.behavior || behavior;
     if (b && b.behaviorType === 'ttl' && b.duration) {
       const n = parseInt(String(b.duration.value), 10);
-      const mult = { h: 3600_000, d: 86_400_000, w: 604_800_000, m: 60_000 }[b.duration.unit];
+      const mult = { s: 1000, m: 60_000, h: 3600_000, d: 86_400_000, w: 604_800_000 }[b.duration.unit];
       if (!Number.isNaN(n) && mult) return n * mult;
     }
     return null;
   }
 
+  /** Convert a Duration AST ({ value, unit }) to milliseconds. */
+  _durationToMs(duration) {
+    if (!duration || duration.value === undefined) return null;
+    const raw = typeof duration.value === 'string' ? duration.value : String(duration.value);
+    const unit = duration.unit || raw.slice(-1);
+    const numeric = parseFloat(raw);
+    if (!Number.isFinite(numeric)) return null;
+    const mult = { s: 1000, m: 60_000, h: 3600_000, d: 86_400_000, w: 604_800_000 }[unit];
+    return mult ? numeric * mult : null;
+  }
+
   /**
    * Normalize a provider result (boolean / number / { possibility, value } /
    * array of edge objects) into an array of partial-graph edge objects. The
    * destination follows the DSL fact's declared shape: unary and value-carrying
    * facts are self-edges on the subject; binary entity facts go subject → object.
+   * Provider-returned edges are validated against the fact's declared typing:
+   * a value-carrying fact must return an object with a value of the declared
+   * type, and possibilities must be in [0, 1]. A violation throws — it is a
+   * provider-authoring error, not a denial.
    */
-  _normalizeProviderEdges(result, factMeta, user, object) {
+  _normalizeProviderEdges(result, factMeta, fact, user, object) {
     const edges = Array.isArray(result) ? result : [result];
     const secondParamType = factMeta.params[1] && factMeta.params[1].type;
-    const defaultDst = factMeta.params.length >= 2 && this._isValueType(secondParamType)
-      ? user
-      : (factMeta.params.length >= 2 ? object : user);
+    const isValueFact = factMeta.params.length >= 2 && this._isValueType(secondParamType);
+    // Sources carry a timestamp in `value` for their recency (`within X`) gate.
+    const isSource = factMeta.kind === 'source';
+    const defaultDst = isValueFact ? user : (factMeta.params.length >= 2 ? object : user);
+    const label = `provider for '${fact}'`;
     const out = [];
     for (const edge of edges) {
       const normalized = typeof edge === 'boolean' || typeof edge === 'number'
-        ? { src: user, dst: defaultDst, possibility: edge === true ? 1 : edge }
-        : {
-          ...(edge.relation ? { relation: edge.relation } : {}),
-          src: edge.src ?? user,
-          dst: edge.dst ?? defaultDst,
-          possibility: edge.possibility ?? 1,
-          ...(edge.value !== undefined ? { value: edge.value } : {}),
-          ...(edge.reliability !== undefined ? { reliability: edge.reliability } : {})
-        };
+        ? (() => {
+            if (isValueFact) {
+              throw new Error(`DSLRuntime: ${label} is a value-carrying fact — return { value, possibility } (got a bare ${typeof edge === 'number' ? 'number' : 'boolean'})`);
+            }
+            const possibility = edge === true ? 1 : edge;
+            this._checkPossibility(possibility, label);
+            return { src: user, dst: defaultDst, possibility };
+          })()
+        : (() => {
+            const possibility = edge.possibility ?? 1;
+            this._checkPossibility(possibility, label);
+            if (edge.value !== undefined) {
+              if (!isValueFact && !isSource) {
+                throw new Error(`DSLRuntime: ${label} returned a value for a non-value fact '${fact}'`);
+              }
+              if (isValueFact) {
+                this._checkScalarValue(secondParamType, edge.value, `${label}.value`);
+              } else if (isSource && (typeof edge.value !== 'number' || Number.isNaN(edge.value))) {
+                throw new Error(`DSLRuntime: ${label} (a source) must return a numeric timestamp in value`);
+              }
+            } else if (isValueFact) {
+              throw new Error(`DSLRuntime: ${label} must supply a 'value' of type ${secondParamType}`);
+            }
+            return {
+              ...(edge.relation ? { relation: edge.relation } : {}),
+              src: edge.src ?? user,
+              dst: edge.dst ?? defaultDst,
+              possibility,
+              ...(edge.value !== undefined ? { value: edge.value } : {}),
+              ...(edge.reliability !== undefined ? { reliability: edge.reliability } : {})
+            };
+          })();
       out.push(normalized);
     }
     return out;
   }
 
+  _checkPossibility(possibility, label) {
+    if (typeof possibility !== 'number' || !Number.isFinite(possibility) || possibility < 0 || possibility > 1) {
+      throw new Error(`DSLRuntime: ${label} returned invalid possibility ${possibility} (expected a number in [0, 1])`);
+    }
+  }
+
   // ---------------------------------------------------------------------------
   // Schema validation helpers
   // ---------------------------------------------------------------------------
@@ -399,6 +467,11 @@ export class DSLRuntime {
     if (this.types.has(typeName)) {
       const { fields } = this.types.get(typeName);
       for (const [name, field] of fields) {
+        // Required fields must be present on insert (`field: type` in the DSL;
+        // `field?: type` marks a field optional).
+        if (field.required && data[name] === undefined) {
+          throw new Error(`DSLRuntime: missing required field '${typeName}.${name}' on node insert`);
+        }
         if (data[name] !== undefined) this._checkFieldValue(field, data[name], `${typeName}.${name}`);
       }
     } else if (this.strictTypes) {
@@ -508,7 +581,7 @@ export class DSLRuntime {
 
   /**
    * The partial-graph requirements of an evidence relation: the declared
-   * injectable facts it depends on.
+   * injectable facts and sources it depends on.
    */
   requiredFacts(relation) {
     const deps = this.dependsOn.get(relation);
@@ -517,6 +590,7 @@ export class DSLRuntime {
     for (const dep of deps) {
       const meta = this.relations.get(dep);
       if (meta && meta.kind === 'fact' && meta.injectable) required.push(dep);
+      if (meta && meta.kind === 'source') required.push(dep);
     }
     return required;
   }
@@ -555,6 +629,11 @@ export class DSLRuntime {
     } else if (meta.params.length === 2) {
       this._checkNodeType(user, meta.params[0].type, 'subject');
       this._checkNodeType(object, meta.params[1].type, 'object');
+      // A value-typed object parameter (can_withdraw(user, amount: number))
+      // carries the expected EDGE VALUE, not a node key — validate the scalar.
+      if (this._isValueType(meta.params[1].type)) {
+        this._checkScalarValue(meta.params[1].type, object, `object of '${relation}'`);
+      }
     } else if (meta.params.length === 1) {
       this._checkNodeType(user, meta.params[0].type, 'subject');
     }
@@ -564,14 +643,16 @@ export class DSLRuntime {
     // provider, if registered, supplies the edge — checking `owns` directly
     // must consult the `owns` provider, not only evidence-mediated checks).
     const required = new Set(this.requiredFacts(relation));
-    if (meta && meta.kind === 'fact') required.add(relation);
+    if (meta && (meta.kind === 'fact' || meta.kind === 'source')) required.add(relation);
     const requiredList = [...required];
     const providers = { ...this.factProviders, ...(options.factProviders || {}) };
     const maxRounds = options.maxProviderRounds ?? 3;
     const partialRelations = [];
     const injectedRelations = []; // { relation, edges, round }
     const missingFacts = [];
+    const warnings = [];
     const satisfied = new Set();  // facts whose edges are in the partial graph
+    const now = this.clock ? this.clock() : Date.now();
 
     if (options.partialGraph && Array.isArray(options.partialGraph.relations)) {
       for (const rel of options.partialGraph.relations) {
@@ -593,8 +674,11 @@ export class DSLRuntime {
         // provider overrides are one-off observations — they bypass the cache
         // entirely (no read, no write) so a fresh override is never masked by
         // a cached registered-provider result, nor does it pollute the cache.
+        // options.cacheProviderResults:false (or the policy default) disables
+        // the cache for this check.
+        const cachingEnabled = options.cacheProviderResults ?? this.cacheProviderResults;
         const isPerCheckOverride = !!(options.factProviders && fact in options.factProviders);
-        const cacheHit = isPerCheckOverride ? null : this._providerCacheGet(fact, user, object);
+        const cacheHit = (cachingEnabled && !isPerCheckOverride) ? this._providerCacheGet(fact, user, object) : null;
         let edges = null;
         let fromCache = false;
         if (cacheHit) {
@@ -625,8 +709,8 @@ export class DSLRuntime {
             satisfied.add(fact);
             continue;
           }
-          edges = this._normalizeProviderEdges(result, factMeta, user, object);
-          if (!isPerCheckOverride) this._providerCacheSet(fact, user, object, edges);
+          edges = this._normalizeProviderEdges(result, factMeta, fact, user, object);
+          if (cachingEnabled && !isPerCheckOverride) this._providerCacheSet(fact, user, object, edges);
         } else {
           missingFacts.push({ relation: fact, reason: 'no_provider' });
           satisfied.add(fact);
@@ -634,11 +718,33 @@ export class DSLRuntime {
         }
 
         // A provider may return edges for relations other than its own; the
-        // injected relation names satisfy those facts too (fixed point).
+        // injected relation names satisfy those facts too (fixed point). Apply
+        // the source recency gate (within X) and drop ghost-node edges.
+        const accepted = [];
         for (const normalized of edges) {
           const injectedRelation = normalized.relation ?? fact;
-          partialRelations.push({ relation: injectedRelation, ...normalized });
-          satisfied.add(injectedRelation);
+          if (factMeta.kind === 'source' && factMeta.withinMs !== null && factMeta.withinMs !== undefined) {
+            if (normalized.value === undefined) {
+              throw new Error(`DSLRuntime: provider for recency-gated source '${fact}' must return a timestamp in value (within ${factMeta.withinMs}ms)`);
+            }
+            if (now - normalized.value > factMeta.withinMs) {
+              missingFacts.push({ relation: fact, reason: 'stale' });
+              continue;
+            }
+          }
+          if (normalized.src !== undefined && !this.arbiter.nodeIdByKey.has(normalized.src)) {
+            warnings.push(`provider for '${fact}' returned an edge with unknown source node '${normalized.src}' — dropped`);
+            continue;
+          }
+          if (normalized.dst !== undefined && !this.arbiter.nodeIdByKey.has(normalized.dst)) {
+            warnings.push(`provider for '${fact}' returned an edge with unknown target node '${normalized.dst}' — dropped`);
+            continue;
+          }
+          accepted.push({ relation: injectedRelation, ...normalized });
+        }
+        for (const normalized of accepted) {
+          partialRelations.push(normalized);
+          satisfied.add(normalized.relation);
         }
         injectedRelations.push({ relation: fact, edges: edges.length, round, cacheHit: fromCache });
         newRelationsThisRound += edges.length;
@@ -655,13 +761,24 @@ export class DSLRuntime {
       };
     }
 
-    const result = this.arbiter.check(user, relation, object, checkOptions);
+    // A value-typed object parameter means the check object IS the expected
+    // edge value, not a node key. Value-carrying facts store edges as
+    // self-edges on the subject, so the underlying check runs on the subject
+    // with the value carried as a per-check gate (options.expectedValue).
+    const isValueObject = meta && meta.params.length === 2 && this._isValueType(meta.params[1].type);
+    const checkObject = isValueObject ? user : object;
+    if (isValueObject) {
+      checkOptions.expectedValue = object;
+    }
+
+    const result = this.arbiter.check(user, relation, checkObject, checkOptions);
 
     return {
       ...result,
       requiredFacts: requiredList,
       providedFacts: injectedRelations.map(r => r.relation),
-      missingFacts
+      missingFacts,
+      warnings
     };
   }
 

src/validation/DSLValidation.js

@@ -141,6 +141,22 @@ function validateDefinitions(program, tables, errors, warnings, source) {
         }));
       }
     }
+
+    // Duplicate field names within a definition silently keep the last
+    // declaration (e.g. `{ id: string id: string }`) — reject loudly instead.
+    const fieldSeen = new Set();
+    for (const field of def.fields || []) {
+      if (fieldSeen.has(field.name)) {
+        errors.push(createError({
+          message: `Duplicate field '${def.name}.${field.name}'.`,
+          rule: 'Each field name must be unique within a definition.',
+          fix: `Remove the duplicate declaration of '${def.name}.${field.name}'.`,
+          location: findLocation(source, field.name),
+          context: formatContext(source, findLocation(source, def.name))
+        }));
+      }
+      fieldSeen.add(field.name);
+    }
   }
 }
 
@@ -1006,6 +1022,31 @@ function formatPegError(error, sourceText, sourceName) {
     message = 'Missing colon after identifier.';
     fix = 'Add ":" between a name and its type.';
     rule = 'Types must be declared using name: Type syntax.';
+  } else {
+    // Targeted hints for common declaration mistakes. The peggy error only
+    // reports "unexpected X"; these heuristics read the source around the
+    // failure to point at the real constraint.
+    const offset = error.location?.start?.offset ?? -1;
+    const before = offset >= 0 ? sourceText.slice(0, offset) : '';
+    const tail = before.split(/\n/).pop() || '';
+    const lastKeyword = (() => {
+      const matches = [...before.matchAll(/\b(fact|relation|source|evidence|measure)\b/g)];
+      return matches.length ? matches[matches.length - 1][1] : null;
+    })();
+
+    if (found === 'w' && lastKeyword === 'fact' || (found === 'w' && lastKeyword === 'relation')) {
+      message = '`within` is only valid on `source` declarations.';
+      fix = 'Move the recency constraint to a `source` declaration, or drop `within` here.';
+      rule = 'Only sources accept a `within` freshness constraint.';
+    } else if (/\bBEHAVES\b/.test(before) && tail.includes('BEHAVES')) {
+      message = 'A declaration can carry only one `BEHAVES` clause.';
+      fix = 'Choose either a behavior (`BEHAVES AS transitive`) or a TTL (`BEHAVES { ttl 1h }`), not both.';
+      rule = '`BEHAVES` may appear at most once per declaration.';
+    } else if (found === 'l' && lastKeyword === 'evidence' && sourceText.slice(offset, offset + 5) === 'limit') {
+      message = '`limit` is only valid on pattern/recursive bodies.';
+      fix = 'Move `limit N` onto the pattern itself, e.g. reports_to(user, *m) { ... } limit N.';
+      rule = 'Only pattern bodies take a recursion depth limit.';
+    }
   }
 
   return createError({

tests/DSLCompiler.test.js

@@ -196,6 +196,36 @@ describe('DSL Compiler', () => {
     assert.ok(invalidResult.errors.length > 0, 'Should have validation errors');
   });
 
+  test('Rejects duplicate fields within a definition', () => {
+    const dupFieldDSL = `
+      definition Employee { id: string id: string }
+    `;
+    const result = compiler.validate(dupFieldDSL);
+    assert.ok(!result.success, 'Duplicate field should fail validation');
+    assert.match(result.errors[0], /Duplicate field 'Employee.id'/);
+  });
+
+  test('Hints at the real constraint for common declaration mistakes', () => {
+    const withinOnFact = compiler.compile(`
+      definition Employee { id: string? }
+      fact owns(user: Employee, doc: Employee) within 1h
+    `, 'err-within');
+    assert.match(withinOnFact.errors[0], /within.*only valid on `source`/);
+
+    const doubleBehaves = compiler.compile(`
+      definition Employee { id: string? }
+      fact rel(user: Employee, doc: Employee) BEHAVES AS transitive BEHAVES { ttl 1h }
+    `, 'err-behaves');
+    assert.match(doubleBehaves.errors[0], /only one `BEHAVES` clause/);
+
+    const limitAfterBody = compiler.compile(`
+      definition Employee { id: string? }
+      fact owns(user: Employee, doc: Employee)
+      evidence can_read(user: Employee, doc: Employee) { owns(user, doc) } limit 5
+    `, 'err-limit');
+    assert.match(limitAfterBody.errors[0], /`limit` is only valid on pattern/);
+  });
+
   test('Rule generation', () => {
     const dsl = `
       definition Employee {

tests/DSLRuntime.test.js

@@ -20,9 +20,9 @@ import { Arbiter } from '@arbiter/core';
 import { DSLRuntime } from '../src/runtime/DSLRuntime.js';
 
 const BASE_DSL = `
-  definition Employee { id: string level: number active: boolean }
-  definition Group { id: string }
-  definition Doc { id: string }
+  definition Employee { id: string? level: number? active: boolean? }
+  definition Group { id: string? }
+  definition Doc { id: string? }
   fact member_of(user: Employee, group: Group)
   fact *owns(user: Employee, doc: Doc)
   fact *user_score(user: Employee, value: number)
@@ -164,8 +164,8 @@ describe('DSLRuntime', () => {
 
   it('derives transitive required facts through evidence composition', async () => {
     const dsl = `
-      definition Employee { id: string }
-      definition Doc { id: string }
+      definition Employee { id: string? }
+      definition Doc { id: string? }
       fact *owns(user: Employee, doc: Doc)
       fact *banned(user: Employee)
       evidence can_read(user: Employee, doc: Doc) { owns(user, doc) }
@@ -191,9 +191,9 @@ describe('DSLRuntime', () => {
 
   it('derives transitive required facts through a condition-step chain', () => {
     const dsl = `
-      definition Employee { id: string }
-      definition Group { id: string }
-      definition Doc { id: string }
+      definition Employee { id: string? }
+      definition Group { id: string? }
+      definition Doc { id: string? }
       fact *member_of(user: Employee, group: Group)
       fact *can_view(group: Group, doc: Doc)
       fact *banned(group: Group)
@@ -205,4 +205,123 @@ describe('DSLRuntime', () => {
     // evidence's requirements, alongside the edge-traversal fact.
     assert.deepEqual(rt.requiredFacts('can_via'), ['member_of', 'can_view', 'banned']);
   });
+
+  it('negates a NOT predicate (1 - possibility)', async () => {
+    const dsl = `
+      definition Employee { id: string? }
+      fact banned(user: Employee)
+      evidence can_enter(user: Employee) { NOT banned(user) }
+    `;
+    // Absent predicate negates to allow.
+    const absent = new DSLRuntime(new Arbiter()).compile(dsl, 'rt-not-absent');
+    absent.addNode('u:1', 'Employee', {});
+    assert.equal((await absent.check('u:1', 'can_enter', 'u:1')).possibility, 1);
+    // Present predicate negates to its complement.
+    const present = new DSLRuntime(new Arbiter()).compile(dsl, 'rt-not-present');
+    present.addNode('u:1', 'Employee', {});
+    present.addRelation('u:1', 'banned', 'u:1', { possibility: 0.9 });
+    const denied = await present.check('u:1', 'can_enter', 'u:1');
+    assert.ok(Math.abs(denied.possibility - 0.1) < 1e-9, `expected 0.1, got ${denied.possibility}`);
+    // Nested inside an AND: the negated child still scopes to the subject.
+    const nested = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      definition Doc { id: string? }
+      fact owns(user: Employee, doc: Doc)
+      fact banned(user: Employee)
+      evidence can_open(user: Employee, doc: Doc) { owns(user, doc) NOT banned(user) }
+    `, 'rt-not-nested');
+    nested.addNode('u:1', 'Employee', {});
+    nested.addNode('doc:9', 'Doc', {});
+    nested.addRelation('u:1', 'owns', 'doc:9', { possibility: 0.8 });
+    nested.addRelation('u:1', 'banned', 'u:1', { possibility: 0.6 });
+    assert.equal((await nested.check('u:1', 'can_open', 'doc:9')).possibility, 0.4);
+  });
+
+  it('resolves BEHAVES AS transitive facts as bounded transitive closure', async () => {
+    const dsl = `
+      definition Employee { id: string? }
+      fact reports_to(user: Employee, boss: Employee) BEHAVES AS transitive
+      evidence can_see(user: Employee, doc: Employee) { reports_to(user, doc) }
+    `;
+    const rt = new DSLRuntime(new Arbiter()).compile(dsl, 'rt-transitive');
+    ['e:1', 'e:2', 'e:3', 'e:4'].forEach(k => rt.addNode(k, 'Employee', {}));
+    rt.addRelation('e:1', 'reports_to', 'e:2', { possibility: 1.0 });
+    rt.addRelation('e:2', 'reports_to', 'e:3', { possibility: 0.9 });
+    rt.addRelation('e:3', 'reports_to', 'e:4', { possibility: 0.8 });
+    // Direct checks on the transitive fact follow multi-hop paths.
+    assert.equal((await rt.check('e:1', 'reports_to', 'e:3')).possibility, 0.9);
+    assert.equal((await rt.check('e:1', 'reports_to', 'e:4')).possibility, 0.8);
+    // Reverse direction does not grant.
+    assert.equal((await rt.check('e:2', 'reports_to', 'e:1')).possibility, 0);
+    // Evidence references inherit the closure.
+    assert.equal((await rt.check('e:1', 'can_see', 'e:4')).possibility, 0.8);
+    // Non-transitive facts stay direct-only.
+    const direct = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      fact knows(user: Employee, peer: Employee)
+      evidence can_ping(user: Employee, doc: Employee) { knows(user, doc) }
+    `, 'rt-nontransitive');
+    ['a:1', 'a:2', 'a:3'].forEach(k => direct.addNode(k, 'Employee', {}));
+    direct.addRelation('a:1', 'knows', 'a:2', { possibility: 1.0 });
+    direct.addRelation('a:2', 'knows', 'a:3', { possibility: 1.0 });
+    assert.equal((await direct.check('a:1', 'can_ping', 'a:3')).possibility, 0);
+  });
+
+  it('bounds transitive closure depth by the fact limit', async () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      fact reports_to(user: Employee, boss: Employee) BEHAVES AS transitive limit 2
+      evidence can_see(user: Employee, doc: Employee) { reports_to(user, doc) }
+    `, 'rt-transitive-limit');
+    ['e:1', 'e:2', 'e:3', 'e:4'].forEach(k => rt.addNode(k, 'Employee', {}));
+    rt.addRelation('e:1', 'reports_to', 'e:2', { possibility: 1.0 });
+    rt.addRelation('e:2', 'reports_to', 'e:3', { possibility: 1.0 });
+    rt.addRelation('e:3', 'reports_to', 'e:4', { possibility: 1.0 });
+    assert.equal((await rt.check('e:1', 'can_see', 'e:3')).possibility, 1.0);
+    assert.equal((await rt.check('e:1', 'can_see', 'e:4')).possibility, 0);
+  });
+
+  it('retrieves sources through providers and gates them by within recency', async () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      definition Doc { id: string? }
+      source *session(user: Employee) within 1h
+      fact *owns(user: Employee, doc: Doc)
+      evidence can_read(user: Employee, doc: Doc) { session(user) owns(user, doc) }
+    `, 'rt-source');
+    rt.addNode('u:1', 'Employee', {});
+    rt.addNode('doc:9', 'Doc', {});
+    assert.ok(rt.relations.has('session'));
+    assert.equal(rt.relations.get('session').kind, 'source');
+    assert.equal(rt.relations.get('session').withinMs, 3_600_000);
+    // A fresh session proof grants.
+    const fresh = await rt.check('u:1', 'can_read', 'doc:9', {
+      factProviders: { session: async () => ({ possibility: 1.0, value: Date.now() }), owns: async () => 0.9 }
+    });
+    assert.equal(fresh.possibility, 0.9);
+    assert.deepEqual(fresh.providedFacts, ['session', 'owns']);
+    // A stale proof (2h old, beyond the 1h window) denies as stale.
+    const stale = await rt.check('u:1', 'can_read', 'doc:9', {
+      factProviders: { session: async () => ({ possibility: 1.0, value: Date.now() - 2 * 3600_000 }), owns: async () => 0.9 }
+    });
+    assert.equal(stale.possibility, 0);
+    assert.deepEqual(stale.missingFacts, [{ relation: 'session', reason: 'stale' }]);
+  });
+
+  it('warns about and drops provider edges referencing unknown nodes', async () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      definition Doc { id: string? }
+      fact *owns(user: Employee, doc: Doc)
+      evidence can_read(user: Employee, doc: Doc) { owns(user, doc) }
+    `, 'rt-ghost');
+    rt.addNode('u:1', 'Employee', {});
+    rt.addNode('doc:9', 'Doc', {});
+    const res = await rt.check('u:1', 'can_read', 'doc:9', {
+      factProviders: { owns: async () => [{ src: 'ghost:1', dst: 'doc:9', possibility: 0.9 }] }
+    });
+    assert.equal(res.possibility, 0);
+    assert.equal(res.warnings.length, 1);
+    assert.match(res.warnings[0], /unknown source node 'ghost:1'/);
+  });
 });

tests/DSLRuntimeCache.test.js

@@ -14,8 +14,8 @@ import { Arbiter } from '@arbiter/core';
 import { DSLRuntime } from '../src/runtime/DSLRuntime.js';
 
 const BASE_DSL = `
-  definition Employee { id: string }
-  definition Doc { id: string }
+  definition Employee { id: string? }
+  definition Doc { id: string? }
   fact *owns(user: Employee, doc: Doc)
   evidence can_read(user: Employee, doc: Doc) { owns(user, doc) }
 `;
@@ -102,8 +102,8 @@ describe('DSLRuntime provider-result caching', () => {
 
   it('invalidateProviderCache() clears all or per relation', async () => {
     const dsl = `
-      definition Employee { id: string }
-      definition Doc { id: string }
+      definition Employee { id: string? }
+      definition Doc { id: string? }
       fact *owns(user: Employee, doc: Doc)
       fact *banned(user: Employee)
       evidence can_read(user: Employee, doc: Doc) { owns(user, doc) }
@@ -151,8 +151,8 @@ describe('DSLRuntime provider-result caching', () => {
 
   it('uses the DSL-declared fact TTL (BEHAVES { ttl X })', async () => {
     const dsl = `
-      definition Employee { id: string }
-      definition Doc { id: string }
+      definition Employee { id: string? }
+      definition Doc { id: string? }
       fact *balance(user: Employee, amount: number) BEHAVES { ttl 1h }
       evidence can_spend(user: Employee, doc: Doc) { balance(user, 1) }
     `;
@@ -173,4 +173,31 @@ describe('DSLRuntime provider-result caching', () => {
     await rt.check('u:1', 'can_spend', 'doc:9');
     assert.equal(calls, 2, 're-invoked past the DSL-declared 1h TTL');
   });
+
+  it('cacheProviderResults:false bypasses the cache per check', async () => {
+    const rt = makeRuntime();
+    rt.addNode('u:1', 'Employee', {});
+    rt.addNode('doc:9', 'Doc', {});
+    let calls = 0;
+    rt.registerFact('owns', async () => { calls++; return 0.9; });
+    await rt.check('u:1', 'can_read', 'doc:9');
+    assert.equal(calls, 1);
+    // Bypass forces a fresh retrieval without clearing the cache.
+    await rt.check('u:1', 'can_read', 'doc:9', { cacheProviderResults: false });
+    assert.equal(calls, 2);
+    // Cache still intact for the next default check.
+    await rt.check('u:1', 'can_read', 'doc:9');
+    assert.equal(calls, 2);
+  });
+
+  it('policy.cacheProviderResults:false disables caching globally', async () => {
+    const rt = makeRuntime({ policy: { cacheProviderResults: false } });
+    rt.addNode('u:1', 'Employee', {});
+    rt.addNode('doc:9', 'Doc', {});
+    let calls = 0;
+    rt.registerFact('owns', async () => { calls++; return 0.9; });
+    await rt.check('u:1', 'can_read', 'doc:9');
+    await rt.check('u:1', 'can_read', 'doc:9');
+    assert.equal(calls, 2, 'no caching when disabled globally');
+  });
 });

tests/DSLRuntimeExt.test.js

@@ -14,8 +14,8 @@ import { Arbiter } from '@arbiter/core';
 import { DSLRuntime } from '../src/runtime/DSLRuntime.js';
 
 const BASE_DSL = `
-  definition Employee { id: string level: number active: boolean }
-  definition Doc { id: string created: timestamp }
+  definition Employee { id: string? level: number? active: boolean? }
+  definition Doc { id: string? created: timestamp? }
   fact *owns(user: Employee, doc: Doc)
   fact *banned(user: Employee)
   evidence can_read(user: Employee, doc: Doc) { owns(user, doc) }
@@ -73,8 +73,8 @@ describe('DSLRuntime extended', () => {
     // edge for a DIFFERENT injectable fact that can_open also requires via
     // composition — here we add a transitive requirement to prove the loop.
     const dsl = `
-      definition Employee { id: string }
-      definition Doc { id: string }
+      definition Employee { id: string? }
+      definition Doc { id: string? }
       fact *owns(user: Employee, doc: Doc)
       fact *granted(user: Employee, doc: Doc)
       evidence base_read(user: Employee, doc: Doc) { owns(user, doc) }
@@ -165,4 +165,33 @@ describe('DSLRuntime extended', () => {
     assert.equal(missed.possibility, 0);
     assert.deepEqual(missed.missingFacts, [{ relation: 'owns', reason: 'no_provider' }]);
   });
+
+  it('recompiling a scope uninstalls its stale relation configs', async () => {
+    const rt = new DSLRuntime(new Arbiter());
+    rt.compile(`
+      definition Employee { id: string? }
+      definition Doc { id: string? }
+      fact owns(user: Employee, doc: Doc)
+      evidence can_read(user: Employee, doc: Doc) { owns(user, doc) }
+    `, 'rt-stale');
+    rt.addNode('u:1', 'Employee', {});
+    rt.addNode('doc:9', 'Doc', {});
+    rt.addRelation('u:1', 'owns', 'doc:9', { possibility: 1.0 });
+    assert.equal(rt.arbiter.check('u:1', 'can_read', 'doc:9').possibility, 1.0);
+
+    // Recompile the SAME scope with a different program: can_read/owns are no
+    // longer declared and must not keep granting. A second scope's relations
+    // would be unaffected (compileMultiple coexistence).
+    rt.compile(`
+      definition Employee { id: string? }
+      definition Doc { id: string? }
+      fact shares(user: Employee, doc: Doc)
+      evidence can_share(user: Employee, doc: Doc) { shares(user, doc) }
+    `, 'rt-stale');
+    const stale = rt.arbiter.check('u:1', 'can_read', 'doc:9');
+    assert.equal(stale.possibility, 0, 'revoked can_read must not keep granting');
+    assert.ok(!rt.arbiter.relationConfigs.has('can_read'));
+    assert.ok(!rt.arbiter.relationConfigs.has('owns'));
+    assert.ok(rt.arbiter.relationConfigs.has('can_share'));
+  });
 });

tests/DSLRuntimeTyping.test.js

@@ -0,0 +1,136 @@
+/**
+ * tests/DSLRuntimeTyping.test.js — duration seconds, required fields, and
+ * type validation of insertions / updates / provider retrievals.
+ *
+ * - Duration literals now accept s/m/h/d/w: `BEHAVES { ttl 30s }` is 30s.
+ * - Definition fields are REQUIRED by default (`field: type`); `field: type?`
+ *   marks a field optional. addNode enforces presence on insert.
+ * - Provider-returned edges are validated against the fact's declared typing:
+ *   a value-carrying fact must return { value, possibility } with a value of
+ *   the declared type, and possibilities must lie in [0, 1].
+ */
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { Arbiter } from '@arbiter/core';
+import { DSLRuntime } from '../src/runtime/DSLRuntime.js';
+
+describe('DSLRuntime typing', () => {
+  it('accepts seconds/minutes/hours/days/weeks in duration literals', async () => {
+    const dsl = `
+      definition Employee { id: string? }
+      definition Doc { id: string? }
+      fact *a(user: Employee, amount: number) BEHAVES { ttl 30s }
+      fact *b(user: Employee, amount: number) BEHAVES { ttl 2m }
+      fact *c(user: Employee, amount: number) BEHAVES { ttl 1h }
+      fact *d(user: Employee, amount: number) BEHAVES { ttl 3d }
+      fact *e(user: Employee, amount: number) BEHAVES { ttl 1w }
+    `;
+    const rt = new DSLRuntime(new Arbiter()).compile(dsl, 'rt-units');
+    assert.equal(rt.relations.get('a').ttlMs, 30_000);
+    assert.equal(rt.relations.get('b').ttlMs, 120_000);
+    assert.equal(rt.relations.get('c').ttlMs, 3_600_000);
+    assert.equal(rt.relations.get('d').ttlMs, 259_200_000);
+    assert.equal(rt.relations.get('e').ttlMs, 604_800_000);
+  });
+
+  it('enforces required definition fields on node insert', () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string level: number active: boolean? }
+    `, 'rt-req');
+    // id and level are required (no `?`); active is optional.
+    assert.throws(() => rt.addNode('u:1', 'Employee', { level: 3 }), /missing required field 'Employee.id'/);
+    assert.throws(() => rt.addNode('u:2', 'Employee', { id: 'u:2' }), /missing required field 'Employee.level'/);
+    rt.addNode('u:3', 'Employee', { id: 'u:3', level: 5 }); // both required, no active -> ok
+    rt.addNode('u:4', 'Employee', { id: 'u:4', level: 5, active: true });
+  });
+
+  it('exposes requiredness in the schema snapshot', () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string level: number? }
+    `, 'rt-schema-req');
+    const employee = rt.getSchema().types.find(t => t.name === 'Employee');
+    assert.equal(employee.fields.find(f => f.name === 'id').required, true);
+    assert.equal(employee.fields.find(f => f.name === 'level').required, false);
+  });
+
+  it('validates a provider-returned value against the declared value type', async () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      definition Doc { id: string? }
+      fact *balance(user: Employee, amount: number)
+      evidence can_spend(user: Employee, doc: Doc) { balance(user, 1) }
+    `, 'rt-valuetype');
+    rt.addNode('u:1', 'Employee', {});
+    rt.addNode('doc:9', 'Doc', {});
+    rt.registerFact('balance', async () => ({ possibility: 1.0, value: 'high' }));
+    await assert.rejects(() => rt.check('u:1', 'can_spend', 'doc:9'), /must be number/);
+  });
+
+  it('requires a value for a value-carrying fact (no bare-number shorthand)', async () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      definition Doc { id: string? }
+      fact *balance(user: Employee, amount: number)
+      evidence can_spend(user: Employee, doc: Doc) { balance(user, 1) }
+    `, 'rt-valshape');
+    rt.addNode('u:1', 'Employee', {});
+    rt.addNode('doc:9', 'Doc', {});
+    rt.registerFact('balance', async () => 0.9);
+    await assert.rejects(() => rt.check('u:1', 'can_spend', 'doc:9'), /value-carrying fact/);
+    rt.registerFact('balance', async () => ({ possibility: 1.0 })); // missing value
+    await assert.rejects(() => rt.check('u:1', 'can_spend', 'doc:9'), /must supply a 'value'/);
+  });
+
+  it('rejects a provider-returned possibility outside [0, 1]', async () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      definition Doc { id: string? }
+      fact *owns(user: Employee, doc: Doc)
+      evidence can_read(user: Employee, doc: Doc) { owns(user, doc) }
+    `, 'rt-poss');
+    rt.addNode('u:1', 'Employee', {});
+    rt.addNode('doc:9', 'Doc', {});
+    rt.registerFact('owns', async () => ({ possibility: 2.0 }));
+    await assert.rejects(() => rt.check('u:1', 'can_read', 'doc:9'), /invalid possibility/);
+  });
+
+  it('enforces a literal value in evidence as an exact edge-value gate', async () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      fact balance(user: Employee, amount: number)
+      evidence can_afford(user: Employee) { balance(user, 5) }
+    `, 'rt-expected-value');
+    rt.addNode('u:1', 'Employee', {});
+    // An edge carrying amount 3 must NOT satisfy balance(user, 5) — without the
+    // gate every balance edge matched regardless of amount (silent over-grant).
+    rt.addRelation('u:1', 'balance', 'u:1', { possibility: 1.0, value: 3 });
+    const denied = await rt.check('u:1', 'can_afford', 'u:1');
+    assert.equal(denied.possibility, 0, 'value-3 edge must not satisfy balance(user, 5)');
+    rt.addRelation('u:1', 'balance', 'u:1', { possibility: 0.8, value: 5 });
+    const granted = await rt.check('u:1', 'can_afford', 'u:1');
+    assert.equal(granted.possibility, 0.8, 'value-5 edge must satisfy balance(user, 5)');
+  });
+
+  it('treats a value-typed evidence OBJECT param as the expected edge value', async () => {
+    const rt = new DSLRuntime(new Arbiter()).compile(`
+      definition Employee { id: string? }
+      fact balance(user: Employee, amount: number)
+      evidence can_withdraw(user: Employee, amount: number) { balance(user, amount) }
+    `, 'rt-value-object');
+    rt.addNode('u:1', 'Employee', {});
+    rt.addRelation('u:1', 'balance', 'u:1', { possibility: 0.9, value: 5 });
+    // The check object is the VALUE, not a node key: grant only on exact match.
+    const granted = await rt.check('u:1', 'can_withdraw', 5);
+    assert.equal(granted.possibility, 0.9, 'value-5 check must match the value-5 edge');
+    const denied = await rt.check('u:1', 'can_withdraw', 3);
+    assert.equal(denied.possibility, 0, 'value-3 check must not match the value-5 edge');
+    // Re-checking the granted value must not hit a value-3 cache entry.
+    const again = await rt.check('u:1', 'can_withdraw', 5);
+    assert.equal(again.possibility, 0.9, 'value-5 re-check must not be served the value-3 result');
+    // Direct fact check with a value object works the same way.
+    const direct = await rt.check('u:1', 'balance', 5);
+    assert.equal(direct.possibility, 0.9, 'direct balance(user, 5) must match the value-5 edge');
+    // A non-scalar object for a value-typed param is rejected loudly.
+    await assert.rejects(() => rt.check('u:1', 'can_withdraw', 'u:1'), /must be number/);
+  });
+});

tests/Recursion.test.js

@@ -0,0 +1,136 @@
+/**
+ * tests/Recursion.test.js — bounded self-recursion (transitive closure).
+ *
+ * An evidence whose config contains a chain step referencing ITSELF is
+ * unrolled at compile time into a bounded transitive closure: a union of
+ * paths — base, hop+base, hop²+base, … — where `hop` is the recursive chain's
+ * steps before the self-reference and the depth N comes from the pattern's
+ * `limit N` (or the compiler's maxRecursionDepth default). The base (the
+ * evidence's non-recursive statements) is verified as a condition step at each
+ * path's terminal node.
+ *
+ * A pure recursion (no base case) cannot grant and is a compile-time error.
+ */
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { Arbiter } from '@arbiter/core';
+import { DSLCompiler } from '../src/DSLCompiler.js';
+
+const BASE = `
+  definition Employee { id: string }
+  definition Doc { id: string }
+  fact can_access(user: Employee, doc: Doc)
+  fact reports_to(user: Employee, manager: Employee)
+`;
+
+const RECURSIVE = `
+  evidence can_access_via(user: Employee, doc: Doc) {
+    can_access(user, doc)
+    reports_to(user, *m) { can_access_via(m, doc) } limit 3
+  }
+`;
+
+function compile(dsl, name = 'rec') {
+  const arb = new Arbiter();
+  const result = new DSLCompiler(arb).compile(dsl, name);
+  return { arb, result };
+}
+
+describe('Bounded self-recursion', () => {
+  it('unrolls into a union of base + bounded hop chains', () => {
+    const { arb, result } = compile(BASE + RECURSIVE);
+    assert.ok(result.success, JSON.stringify(result.errors));
+    const cfg = arb.relationConfigs.get('can_access_via');
+    assert.equal(cfg.type, 'logical');
+    assert.ok(cfg.union, 'recursion should compile to a union of paths');
+    // base + 3 hops (limit 3)
+    assert.equal(cfg.union.rules.length, 4);
+  });
+
+  it('grants through the base case and through multi-hop chains', () => {
+    const { arb, result } = compile(BASE + RECURSIVE);
+    assert.ok(result.success);
+    arb.addNode('u:1', 'Employee'); arb.addNode('m:1', 'Employee'); arb.addNode('m2:1', 'Employee'); arb.addNode('doc:9', 'Doc');
+    // base
+    arb.addRelation('u:1', 'can_access', 'doc:9', { possibility: 1.0 });
+    assert.equal(arb.check('u:1', 'can_access_via', 'doc:9').possibility, 1.0);
+    // 1-hop: u -> m -> doc
+    arb.removeRelation('u:1', 'can_access', 'doc:9');
+    arb.addRelation('u:1', 'reports_to', 'm:1', { possibility: 1.0 });
+    arb.addRelation('m:1', 'can_access', 'doc:9', { possibility: 0.7 });
+    assert.equal(arb.check('u:1', 'can_access_via', 'doc:9').possibility, 0.7);
+    // 2-hop: u -> m -> m2 -> doc
+    arb.addRelation('m:1', 'reports_to', 'm2:1', { possibility: 1.0 });
+    arb.addRelation('m2:1', 'can_access', 'doc:9', { possibility: 0.5 });
+    // union takes the best path: max(0.7, 0.5) = 0.7
+    assert.equal(arb.check('u:1', 'can_access_via', 'doc:9').possibility, 0.7);
+    // 2-hop alone (remove the 1-hop can_access)
+    arb.removeRelation('m:1', 'can_access', 'doc:9');
+    assert.equal(arb.check('u:1', 'can_access_via', 'doc:9').possibility, 0.5);
+  });
+
+  it('enforces the recursion depth limit', () => {
+    const { arb, result } = compile(`
+      ${BASE}
+      evidence can_access_via(user: Employee, doc: Doc) {
+        can_access(user, doc)
+        reports_to(user, *m) { can_access_via(m, doc) } limit 2
+      }
+    `);
+    assert.ok(result.success);
+    arb.addNode('u:1', 'Employee'); arb.addNode('m:1', 'Employee'); arb.addNode('m2:1', 'Employee'); arb.addNode('m3:1', 'Employee'); arb.addNode('doc:9', 'Doc');
+    arb.addRelation('u:1', 'reports_to', 'm:1', { possibility: 1.0 });
+    arb.addRelation('m:1', 'reports_to', 'm2:1', { possibility: 1.0 });
+    arb.addRelation('m2:1', 'reports_to', 'm3:1', { possibility: 1.0 });
+    arb.addRelation('m2:1', 'can_access', 'doc:9', { possibility: 0.5 }); // 2 hops
+    arb.addRelation('m3:1', 'can_access', 'doc:9', { possibility: 0.9 }); // 3 hops
+    assert.equal(arb.check('u:1', 'can_access_via', 'doc:9').possibility, 0.5);
+    arb.removeRelation('m2:1', 'can_access', 'doc:9');
+    // only the 3-hop path remains — beyond the limit -> denied
+    assert.equal(arb.check('u:1', 'can_access_via', 'doc:9').possibility, 0);
+  });
+
+  it('uses the compiler maxRecursionDepth default when no limit is given', () => {
+    const dsl = `
+      ${BASE}
+      evidence can_access_via(user: Employee, doc: Doc) {
+        can_access(user, doc)
+        reports_to(user, *m) { can_access_via(m, doc) }
+      }
+    `;
+    const { arb, result } = compile(dsl);
+    assert.ok(result.success, JSON.stringify(result.errors));
+    // default depth 3 -> base + 3 hops
+    assert.equal(arb.relationConfigs.get('can_access_via').union.rules.length, 4);
+    // a deeper path (4 hops) is not granted
+    arb.addNode('u:1', 'Employee'); arb.addNode('m:1', 'Employee'); arb.addNode('m2:1', 'Employee'); arb.addNode('m3:1', 'Employee'); arb.addNode('m4:1', 'Employee'); arb.addNode('doc:9', 'Doc');
+    arb.addRelation('u:1', 'reports_to', 'm:1', { possibility: 1.0 });
+    arb.addRelation('m:1', 'reports_to', 'm2:1', { possibility: 1.0 });
+    arb.addRelation('m2:1', 'reports_to', 'm3:1', { possibility: 1.0 });
+    arb.addRelation('m3:1', 'reports_to', 'm4:1', { possibility: 1.0 });
+    arb.addRelation('m4:1', 'can_access', 'doc:9', { possibility: 1.0 });
+    assert.equal(arb.check('u:1', 'can_access_via', 'doc:9').possibility, 0, '4-hop path exceeds default depth');
+  });
+
+  it('rejects a pure recursion with no base case', () => {
+    const { result } = compile(`
+      ${BASE}
+      evidence can_access_via(user: Employee, doc: Doc) {
+        reports_to(user, *m) { can_access_via(m, doc) } limit 3
+      }
+    `);
+    assert.equal(result.success, false);
+    assert.ok(result.errors.some(e => /no base case/.test(e)), JSON.stringify(result.errors));
+  });
+
+  it('keeps mutual (non-self) cycles a compile error', () => {
+    const { result } = compile(`
+      ${BASE}
+      fact peer(user: Employee, other: Employee)
+      evidence a(user: Employee, doc: Doc) { peer(user, *p) { b(p, doc) } }
+      evidence b(user: Employee, doc: Doc) { peer(user, *p) { a(p, doc) } }
+    `);
+    assert.equal(result.success, false);
+    assert.ok(result.errors.some(e => /[Cc]yclic/.test(e)), JSON.stringify(result.errors));
+  });
+});