feat: sources wired as recency-gated injectables; transitive closure, NOT scoping, recompile-scope uninstall; targeted parse errors

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.

src/DSLCompiler.js

@@ -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

@@ -11,6 +11,14 @@ export class RuleGenerator {
     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;
   }
@@ -20,10 +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
@@ -41,6 +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
@@ -109,9 +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,
@@ -123,6 +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 } : {})
     });
   }
 
@@ -298,7 +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);
@@ -317,15 +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;
     }
@@ -482,6 +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,
@@ -505,6 +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;
   }
 
@@ -947,7 +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);
     }
@@ -962,6 +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,
@@ -975,6 +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;
   }
 
@@ -1391,6 +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,
@@ -1418,6 +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;
   }
 
@@ -1531,6 +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);
@@ -1542,6 +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/runtime/DSLRuntime.js

@@ -110,6 +110,9 @@ export class DSLRuntime {
     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]) => ({
@@ -117,7 +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). */
@@ -148,6 +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',
@@ -309,6 +324,17 @@ export class DSLRuntime {
     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
@@ -323,6 +349,8 @@ export class DSLRuntime {
     const edges = Array.isArray(result) ? result : [result];
     const secondParamType = factMeta.params[1] && factMeta.params[1].type;
     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 = [];
@@ -340,10 +368,14 @@ export class DSLRuntime {
             const possibility = edge.possibility ?? 1;
             this._checkPossibility(possibility, label);
             if (edge.value !== undefined) {
-              if (!isValueFact) {
+              if (!isValueFact && !isSource) {
                 throw new Error(`DSLRuntime: ${label} returned a value for a non-value fact '${fact}'`);
               }
-              this._checkScalarValue(secondParamType, edge.value, `${label}.value`);
+              if (isValueFact) {
+                this._checkScalarValue(secondParamType, edge.value, `${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}`);
             }
@@ -549,7 +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);
@@ -558,6 +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;
   }
@@ -596,6 +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');
     }
@@ -605,14 +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) {
@@ -678,11 +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;
@@ -699,13 +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({