diff --git a/packages/server/src/schema/neo4j-schema.ts b/packages/server/src/schema/neo4j-schema.ts
index f05642ce..f558cac1 100644
--- a/packages/server/src/schema/neo4j-schema.ts
+++ b/packages/server/src/schema/neo4j-schema.ts
@@ -5,7 +5,7 @@ export const typeDefs = gql`
   enum NodeType {
     # Legacy types (for backward compatibility)
     OUTCOME
-    
+
     # Strategic Planning
     EPIC
     INITIATIVE
@@ -200,6 +200,7 @@ export const typeDefs = gql`
     VALIDATES
     REFERENCES
     CONTAINS
+    SATISFIES
   }
 
   enum ContributorType {
diff --git a/packages/web/src/constants/__tests__/ontology.test.ts b/packages/web/src/constants/__tests__/ontology.test.ts
new file mode 100644
index 00000000..d117653c
--- /dev/null
+++ b/packages/web/src/constants/__tests__/ontology.test.ts
@@ -0,0 +1,28 @@
+import { describe, it, expect } from 'vitest';
+import {
+  isValidWorkItemType, isValidRelationshipType, getTypeConfig, getRelationshipConfig,
+  WORK_ITEM_TYPES, RELATIONSHIP_TYPES,
+} from '../workItemConstants';
+
+describe('ontology layer: REQUIREMENT type + SATISFIES edge (#27)', () => {
+  it('REQUIREMENT is a valid work item type with a config', () => {
+    expect(isValidWorkItemType('REQUIREMENT')).toBe(true);
+    const cfg = getTypeConfig('REQUIREMENT' as any);
+    expect(cfg.label).toBe('Requirement');
+    expect(cfg.value).toBe('REQUIREMENT');
+    expect(cfg.hexColor).toMatch(/^#/);
+    expect(WORK_ITEM_TYPES.REQUIREMENT).toBeTruthy();
+  });
+
+  it('SATISFIES is a valid relationship type with a config', () => {
+    expect(isValidRelationshipType('SATISFIES')).toBe(true);
+    const cfg = getRelationshipConfig('SATISFIES' as any);
+    expect(cfg.label).toBe('Satisfies');
+    expect(cfg.type).toBe('SATISFIES');
+    expect(RELATIONSHIP_TYPES.SATISFIES).toBeTruthy();
+  });
+
+  it('isValidRelationshipType rejects unknown types', () => {
+    expect(isValidRelationshipType('NONSENSE')).toBe(false);
+  });
+});
diff --git a/packages/web/src/constants/workItemConstants.tsx b/packages/web/src/constants/workItemConstants.tsx
index c738f1ed..028ab07a 100644
--- a/packages/web/src/constants/workItemConstants.tsx
+++ b/packages/web/src/constants/workItemConstants.tsx
@@ -96,7 +96,7 @@ export {
 // ============================
 
 // Work item types define what kind of work this represents
-export type WorkItemType = 'EPIC' | 'MILESTONE' | 'OUTCOME' | 'FEATURE' | 'TASK' | 'BUG' | 'IDEA' | 'RESEARCH' | 'DEFAULT';
+export type WorkItemType = 'EPIC' | 'MILESTONE' | 'OUTCOME' | 'FEATURE' | 'TASK' | 'BUG' | 'IDEA' | 'RESEARCH' | 'REQUIREMENT' | 'DEFAULT';
 
 // Work item statuses represent the current state of progress (9 total statuses)
 // NOT_STARTED is the default status for new items
@@ -165,6 +165,16 @@ export const WORK_ITEM_TYPES: Record<WorkItemType, TypeOption> = {
     borderColor: 'border-gray-500/30',
     hexColor: '#9ca3af'
   },
+  REQUIREMENT: {
+    value: 'REQUIREMENT',
+    label: 'Requirement',
+    description: 'A requirement that tasks satisfy (ontology layer)',
+    icon: ClipboardList,
+    color: 'text-sky-400',
+    bgColor: 'bg-sky-400/10',
+    borderColor: 'border-sky-400/30',
+    hexColor: '#38bdf8'
+  },
   EPIC: {
     value: 'EPIC',
     label: 'Epic',
@@ -620,6 +630,7 @@ export type RelationshipType =
   | 'VALIDATES'       // Source tests/validates target
   | 'REFERENCES'      // Source references/cites target
   | 'CONTAINS'        // Source contains/encompasses target
+  | 'SATISFIES'       // Source (task) satisfies target (requirement) — ontology layer
   | 'DEFAULT_EDGE';   // Generic connection
 
 export interface RelationshipOption {
@@ -640,6 +651,14 @@ export const RELATIONSHIP_TYPES: Record<RelationshipType, RelationshipOption> =
     color: 'text-gray-400',
     hexColor: '#9ca3af'
   },
+  SATISFIES: {
+    type: 'SATISFIES',
+    label: 'Satisfies',
+    description: 'Source task satisfies the target requirement (ontology layer)',
+    icon: CheckCircle,
+    color: 'text-sky-400',
+    hexColor: '#38bdf8'
+  },
   DEPENDS_ON: {
     type: 'DEPENDS_ON',
     label: 'Depends On',
@@ -743,6 +762,10 @@ export const RELATIONSHIP_TYPES: Record<RelationshipType, RelationshipOption> =
 // ============================
 
 // Get relationship configuration
+export const isValidRelationshipType = (type: string): type is RelationshipType => {
+  return Object.keys(RELATIONSHIP_TYPES).includes(type as RelationshipType);
+};
+
 export const getRelationshipConfig = (type: RelationshipType): RelationshipOption => {
   return RELATIONSHIP_TYPES[type] || RELATIONSHIP_TYPES.RELATES_TO;
 };