db created, added tests -- tentative

Corrected a typo in the README regarding 'simply'.

README.md

@@ -1,40 +1,75 @@
-# kongruity app
+# kongruity
 
-kongruity employs Large Language Model ("LLM") semantic grouping functionality to cluster large volumes of "to dos" or issue tags in development (or other) settings, according to thematic or topical similarity.
+kongruity pulls in the unstructured artifacts of the creative-engineering process -- to-dos, action items, agile tickets, Jira comment threads, Slack threads, retrospective notes -- and synthesizes them into semantically coherent, prioritized clusters ready for implementation planning.
 
-(To learn more about this topic, see, e.g., [Kozlowski A., Boutyline A., Semantic Structure in Large Language Model Embeddings Aug. 2025, arXiv:2508.10003v1:04 Aug 2025](https://arxiv.org/html/2508.10003v1)).
+In kongruity world, these artifacts are "sticky notes." A board full of them looks chaotic. With a click, an LLM analyzes their semantic meaning and groups them into thematic clusters, each with a descriptive header. 
 
-In the world of kongruity, these "to dos" are called "sticky notes."  kongruity's React/Vite UI views a board of seemingly chaotic "sticky notes".  But with one click, they are transformed into manageable, actionable groups, each with a header that explains the group semantic interrelation.
+An independent embedding-based evaluation scores clustering quality, so the output is data-backed. From there, teams can simply drag-and-rank clusters by implementation priority, turning noise into an actionable workflow.
 
-The backend is an Express API that serves "sticky note" data and proxies semantic grouping requests to Antrhopic Claude.  
+## How it works
 
-Developers may feel free to install other LLM SDKs and alter the syntax at backend/services/clustering.service.js to experiment with any LLM model/platform they prefer.
+1. **Ingest** — Sticky notes are loaded and displayed on a board.
+2. **Cluster** — An LLM reads every note and groups them by semantic similarity (not keywords).
+3. **Evaluate** — In parallel, a separate embedding model (Voyage AI) generates vector representations of each note. A silhouette-based cohesion score measures how well-separated and internally consistent clusters are. The score is displayed alongside the results.
+4. **Validate** — Structural checks confirm every note is assigned to exactly one cluster, no clusters are empty, and labels are present.
+5. **Prioritize** — Clusters appear ranked and are drag-reorderable. Teams set implementation priority by dragging clusters into position.
+
+## Dev implementation note
+
+Developers may swap in other LLM SDKs/APIs and alter prompt syntax in `backend/services/clustering.service.js` to experiment with any model or platform.
 
 ## Prerequisites
 
 - Node.js (v18 or later recommended)
-- An [Anthropic API key](https://console.anthropic.com/)
+- PostgreSQL (v14 or later recommended)
+- An [Anthropic API key](https://console.anthropic.com/) (or other LLM platform, for clustering)
+- A [Voyage AI API key](https://dash.voyageai.com/) (for embedding-based evaluation)
 
 ## Setup
 
-### 1. Unzip the project
+### 1. Clone the repository
 
 ```bash
-unzip kongruity.zip
+git clone https://github.com/kjannette/kongruity_
 cd kongruity
 ```
 
 ### 2. Create an environment file
 
-The backend expects a `.env` file containing an Anthropic API key in the root `backend/` directory. This file is git-ignored and must be created manually:
+The backend expects a `.env` file in the `backend/` directory. This file is git-ignored and must be created manually:
 
 ```bash
-echo 'ANTHROPIC_API_KEY=<your Anthropic API key>' > backend/.env
+cat > backend/.env << 'EOF'
+ANTHROPIC_API_KEY=<your Anthropic API key> (or other LLM platform key)
+VOYAGEAI_API_KEY=<your Voyage AI API key>
+DATABASE_URL=postgresql://<user>:<password>@localhost:5432/kongruity
+EOF
 ```
 
-Replace `<your Anthropic API key>` with your actual key.
+Replace placeholder values with your actual keys and database credentials.
 
-### 3. Install dependencies
+### 3. Set up the database
+
+Create a PostgreSQL database for the project:
+
+```bash
+createdb kongruity
+```
+
+Run the migration to create tables:
+
+```bash
+cd backend
+npm run db:migrate
+```
+
+Seed the database with the sample sticky notes:
+
+```bash
+npm run db:seed
+```
+
+### 4. Install dependencies
 
 ```bash
 cd backend
@@ -48,7 +83,7 @@ npm install
 
 ## Run the app
 
-### Start the backend - Production Mode
+### Start the backend — Production mode
 
 From the `backend/` directory:
 
@@ -58,15 +93,15 @@ npm run start
 
 The API server starts on **http://localhost:3001** (configurable via the `PORT` environment variable).
 
-### Start the backend - Development mode
+### Start the backend — Development mode
 
-To start using Nodemon for "hot reloads," if developing your own features:
+To start using Nodemon for hot reloads while developing:
 
 ```bash
 npm run dev
 ```
 
-### Build the frontend - Production mode
+### Build the frontend — Production mode
 
 From the `frontend/` directory:
 
@@ -74,13 +109,14 @@ From the `frontend/` directory:
 npm run build
 ```
 
-### Start the frontend - Development mode
+### Start the frontend — Development mode
 
 From the `frontend/` directory:
 
 ```bash
 npm run dev
 ```
+
 The Vite dev server starts on **http://localhost:5173** by default. Open that URL in a browser.
 
 ## Running tests
@@ -92,7 +128,8 @@ From the `backend/` directory:
 ```bash
 npm test
 ```
-Backend tests use Supertest for HTTP assertions.
+
+Backend tests use Vitest with Supertest for HTTP assertions.
 
 ### Frontend tests
 
@@ -102,7 +139,7 @@ From the `frontend/` directory:
 npm test
 ```
 
-This runs `vitest run` with jsdom. For watch mode, during development:
+This runs Vitest with jsdom. For watch mode during development:
 
 ```bash
 npm run test:watch

backend/app.js

@@ -6,7 +6,6 @@ const app = express();
 
 app.use(cors());
 app.use(express.json());
-
 app.use('/v1/notes', router);
 
 app.use((req, res) => {

backend/db/index.js

@@ -0,0 +1,13 @@
+import pg from 'pg';
+
+const pool = new pg.Pool({
+  connectionString: process.env.DATABASE_URL,
+});
+
+export const query = (text, params) => pool.query(text, params);
+
+export const getPool = () => pool;
+
+export const close = () => pool.end();
+
+export default pool;

backend/db/migrate.js

@@ -0,0 +1,30 @@
+import 'dotenv/config';
+import { query, close } from './index.js';
+
+const up = `
+CREATE TABLE IF NOT EXISTS notes (
+  id          VARCHAR(64) PRIMARY KEY,
+  text        TEXT NOT NULL,
+  x           INTEGER DEFAULT 0,
+  y           INTEGER DEFAULT 0,
+  author      VARCHAR(128),
+  color       VARCHAR(32) DEFAULT 'yellow',
+  source_meta JSONB DEFAULT '{}',
+  created_at  TIMESTAMPTZ DEFAULT NOW(),
+  updated_at  TIMESTAMPTZ DEFAULT NOW()
+);
+`;
+
+const run = async () => {
+  try {
+    await query(up);
+    console.log('Migration complete — notes table ready.');
+  } catch (err) {
+    console.error('Migration failed:', err.message);
+    process.exit(1);
+  } finally {
+    await close();
+  }
+};
+
+run();

backend/db/notes.dao.js

@@ -0,0 +1,54 @@
+import { query } from './index.js';
+
+export const getAllNotes = async () => {
+  const { rows } = await query(
+    'SELECT id, text, x, y, author, color FROM notes ORDER BY id'
+  );
+  return rows;
+};
+
+export const getNoteById = async (id) => {
+  const { rows } = await query(
+    'SELECT id, text, x, y, author, color FROM notes WHERE id = $1',
+    [id]
+  );
+  return rows[0] || null;
+};
+
+export const createNote = async (note) => {
+  const { rows } = await query(
+    `INSERT INTO notes (id, text, x, y, author, color)
+     VALUES ($1, $2, $3, $4, $5, $6)
+     RETURNING id, text, x, y, author, color`,
+    [note.id, note.text, note.x ?? 0, note.y ?? 0, note.author, note.color ?? 'yellow']
+  );
+  return rows[0];
+};
+
+export const createNotes = async (notes) => {
+  const values = [];
+  const placeholders = [];
+
+  notes.forEach((note, i) => {
+    const offset = i * 6;
+    placeholders.push(
+      `($${offset + 1}, $${offset + 2}, $${offset + 3}, $${offset + 4}, $${offset + 5}, $${offset + 6})`
+    );
+    values.push(
+      note.id,
+      note.text,
+      note.x ?? 0,
+      note.y ?? 0,
+      note.author,
+      note.color ?? 'yellow'
+    );
+  });
+
+  const { rows } = await query(
+    `INSERT INTO notes (id, text, x, y, author, color)
+     VALUES ${placeholders.join(', ')}
+     RETURNING id, text, x, y, author, color`,
+    values
+  );
+  return rows;
+};

backend/db/seed.js

@@ -0,0 +1,40 @@
+import 'dotenv/config';
+import { readFile } from 'fs/promises';
+import { query, close } from './index.js';
+
+const NOTES_PATH = new URL('../data/notes.json', import.meta.url);
+
+const run = async () => {
+  try {
+    const raw = await readFile(NOTES_PATH, 'utf-8');
+    const notes = JSON.parse(raw);
+
+    const insertQuery = `
+      INSERT INTO notes (id, text, x, y, author, color)
+      VALUES ($1, $2, $3, $4, $5, $6)
+      ON CONFLICT (id) DO NOTHING
+    `;
+
+    let inserted = 0;
+    for (const note of notes) {
+      const result = await query(insertQuery, [
+        note.id,
+        note.text,
+        note.x,
+        note.y,
+        note.author,
+        note.color,
+      ]);
+      inserted += result.rowCount;
+    }
+
+    console.log(`Seed complete — ${inserted} notes inserted (${notes.length - inserted} already existed).`);
+  } catch (err) {
+    console.error('Seed failed:', err.message);
+    process.exit(1);
+  } finally {
+    await close();
+  }
+};
+
+run();

backend/package-lock.json

@@ -11,7 +11,9 @@
                 "@anthropic-ai/sdk": "^0.74.0",
                 "cors": "^2.8.5",
                 "dotenv": "^16.4.7",
-                "express": "^4.21.2"
+                "express": "^4.21.2",
+                "pg": "^8.18.0",
+                "voyageai": "^0.1.0"
             },
             "devDependencies": {
                 "nodemon": "^3.1.9",
@@ -1013,6 +1015,18 @@
                 "url": "https://opencollective.com/vitest"
             }
         },
+        "node_modules/abort-controller": {
+            "version": "3.0.0",
+            "resolved": "https://registry.npmjs.org/abort-controller/-/abort-controller-3.0.0.tgz",
+            "integrity": "sha512-h8lQ8tacZYnR3vNQTgibj+tODHI5/+l06Au2Pcriv/Gmet0eaj4TwWH41sO9wnHDiQsEj19q0drzdWdeAHtweg==",
+            "license": "MIT",
+            "dependencies": {
+                "event-target-shim": "^5.0.0"
+            },
+            "engines": {
+                "node": ">=6.5"
+            }
+        },
         "node_modules/accepts": {
             "version": "1.3.8",
             "resolved": "https://registry.npmjs.org/accepts/-/accepts-1.3.8.tgz",
@@ -1067,7 +1081,6 @@
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-            "dev": true,
             "license": "MIT"
         },
         "node_modules/balanced-match": {
@@ -1077,6 +1090,26 @@
             "dev": true,
             "license": "MIT"
         },
+        "node_modules/base64-js": {
+            "version": "1.5.1",
+            "resolved": "https://registry.npmjs.org/base64-js/-/base64-js-1.5.1.tgz",
+            "integrity": "sha512-AKpaYlHn8t4SVbOHCy+b5+KKgvR4vrsD8vbvrbiQJps7fKDTkjkDry6ji0rUJjC0kzbNePLwzxq8iypo41qeWA==",
+            "funding": [
+                {
+                    "type": "github",
+                    "url": "https://github.com/sponsors/feross"
+                },
+                {
+                    "type": "patreon",
+                    "url": "https://www.patreon.com/feross"
+                },
+                {
+                    "type": "consulting",
+                    "url": "https://feross.org/support"
+                }
+            ],
+            "license": "MIT"
+        },
         "node_modules/binary-extensions": {
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             "resolved": "https://registry.npmjs.org/binary-extensions/-/binary-extensions-2.3.0.tgz",
@@ -1138,6 +1171,30 @@
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             }
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+        "node_modules/buffer": {
+            "version": "6.0.3",
+            "resolved": "https://registry.npmjs.org/buffer/-/buffer-6.0.3.tgz",
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+            "funding": [
+                {
+                    "type": "github",
+                    "url": "https://github.com/sponsors/feross"
+                },
+                {
+                    "type": "patreon",
+                    "url": "https://www.patreon.com/feross"
+                },
+                {
+                    "type": "consulting",
+                    "url": "https://feross.org/support"
+                }
+            ],
+            "license": "MIT",
+            "dependencies": {
+                "base64-js": "^1.3.1",
+                "ieee754": "^1.2.1"
+            }
+        },
         "node_modules/bytes": {
             "version": "3.1.2",
             "resolved": "https://registry.npmjs.org/bytes/-/bytes-3.1.2.tgz",
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-            "dev": true,
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@@ -1314,7 +1370,6 @@
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-            "dev": true,
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@@ -1432,7 +1487,6 @@
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-            "dev": true,
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             "dependencies": {
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@@ -1511,6 +1565,24 @@
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             }
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+        "node_modules/event-target-shim": {
+            "version": "5.0.1",
+            "resolved": "https://registry.npmjs.org/event-target-shim/-/event-target-shim-5.0.1.tgz",
+            "integrity": "sha512-i/2XbnSz/uxRCU6+NdVJgKWDTM427+MqYbkQzD321DuCQJUqOuJKIA0IM2+W2xtYHdKOmZ4dR6fExsd4SXL+WQ==",
+            "license": "MIT",
+            "engines": {
+                "node": ">=6"
+            }
+        },
+        "node_modules/events": {
+            "version": "3.3.0",
+            "resolved": "https://registry.npmjs.org/events/-/events-3.3.0.tgz",
+            "integrity": "sha512-mQw+2fkQbALzQ7V0MY0IqdnXNOeTtP4r0lN9z7AAawCXgqea7bDii20AYrIBrFd/Hx0M2Ocz6S111CaFkUcb0Q==",
+            "license": "MIT",
+            "engines": {
+                "node": ">=0.8.x"
+            }
+        },
         "node_modules/expect-type": {
             "version": "1.3.0",
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-            "dev": true,
             "license": "MIT",
             "dependencies": {
                 "asynckit": "^0.4.0",
@@ -1622,6 +1693,15 @@
                 "node": ">= 6"
             }
         },
+        "node_modules/formdata-node": {
+            "version": "6.0.3",
+            "resolved": "https://registry.npmjs.org/formdata-node/-/formdata-node-6.0.3.tgz",
+            "integrity": "sha512-8e1++BCiTzUno9v5IZ2J6bv4RU+3UKDmqWUQD0MIMVCd9AdhWkO1gw57oo1mNEX1dMq2EGI+FbWz4B92pscSQg==",
+            "license": "MIT",
+            "engines": {
+                "node": ">= 18"
+            }
+        },
         "node_modules/formidable": {
             "version": "3.5.4",
             "resolved": "https://registry.npmjs.org/formidable/-/formidable-3.5.4.tgz",
@@ -1770,7 +1850,6 @@
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-            "dev": true,
             "license": "MIT",
             "dependencies": {
                 "has-symbols": "^1.0.3"
@@ -1826,6 +1905,26 @@
                 "node": ">=0.10.0"
             }
         },
+        "node_modules/ieee754": {
+            "version": "1.2.1",
+            "resolved": "https://registry.npmjs.org/ieee754/-/ieee754-1.2.1.tgz",
+            "integrity": "sha512-dcyqhDvX1C46lXZcVqCpK+FtMRQVdIMN6/Df5js2zouUsqG7I6sFxitIC+7KYK29KdXOLHdu9zL4sFnoVQnqaA==",
+            "funding": [
+                {
+                    "type": "github",
+                    "url": "https://github.com/sponsors/feross"
+                },
+                {
+                    "type": "patreon",
+                    "url": "https://www.patreon.com/feross"
+                },
+                {
+                    "type": "consulting",
+                    "url": "https://feross.org/support"
+                }
+            ],
+            "license": "BSD-3-Clause"
+        },
         "node_modules/ignore-by-default": {
             "version": "1.0.1",
             "resolved": "https://registry.npmjs.org/ignore-by-default/-/ignore-by-default-1.0.1.tgz",
@@ -1894,6 +1993,12 @@
                 "node": ">=0.12.0"
             }
         },
+        "node_modules/js-base64": {
+            "version": "3.7.2",
+            "resolved": "https://registry.npmjs.org/js-base64/-/js-base64-3.7.2.tgz",
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+            "license": "BSD-3-Clause"
+        },
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             "resolved": "https://registry.npmjs.org/json-schema-to-ts/-/json-schema-to-ts-3.1.1.tgz",
@@ -2033,6 +2138,26 @@
                 "node": ">= 0.6"
             }
         },
+        "node_modules/node-fetch": {
+            "version": "2.7.0",
+            "resolved": "https://registry.npmjs.org/node-fetch/-/node-fetch-2.7.0.tgz",
+            "integrity": "sha512-c4FRfUm/dbcWZ7U+1Wq0AwCyFL+3nt2bEw05wfxSz+DWpWsitgmSgYmy2dQdWyKC1694ELPqMs/YzUSNozLt8A==",
+            "license": "MIT",
+            "dependencies": {
+                "whatwg-url": "^5.0.0"
+            },
+            "engines": {
+                "node": "4.x || >=6.0.0"
+            },
+            "peerDependencies": {
+                "encoding": "^0.1.0"
+            },
+            "peerDependenciesMeta": {
+                "encoding": {
+                    "optional": true
+                }
+            }
+        },
         "node_modules/nodemon": {
             "version": "3.1.11",
             "resolved": "https://registry.npmjs.org/nodemon/-/nodemon-3.1.11.tgz",
@@ -2173,6 +2298,96 @@
             "dev": true,
             "license": "MIT"
         },
+        "node_modules/pg": {
+            "version": "8.18.0",
+            "resolved": "https://registry.npmjs.org/pg/-/pg-8.18.0.tgz",
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+            "license": "MIT",
+            "peer": true,
+            "dependencies": {
+                "pg-connection-string": "^2.11.0",
+                "pg-pool": "^3.11.0",
+                "pg-protocol": "^1.11.0",
+                "pg-types": "2.2.0",
+                "pgpass": "1.0.5"
+            },
+            "engines": {
+                "node": ">= 16.0.0"
+            },
+            "optionalDependencies": {
+                "pg-cloudflare": "^1.3.0"
+            },
+            "peerDependencies": {
+                "pg-native": ">=3.0.1"
+            },
+            "peerDependenciesMeta": {
+                "pg-native": {
+                    "optional": true
+                }
+            }
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+        "node_modules/pg-cloudflare": {
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+            "license": "MIT",
+            "optional": true
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+        "node_modules/pg-connection-string": {
+            "version": "2.11.0",
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+            "license": "MIT"
+        },
+        "node_modules/pg-int8": {
+            "version": "1.0.1",
+            "resolved": "https://registry.npmjs.org/pg-int8/-/pg-int8-1.0.1.tgz",
+            "integrity": "sha512-WCtabS6t3c8SkpDBUlb1kjOs7l66xsGdKpIPZsg4wR+B3+u9UAum2odSsF9tnvxg80h4ZxLWMy4pRjOsFIqQpw==",
+            "license": "ISC",
+            "engines": {
+                "node": ">=4.0.0"
+            }
+        },
+        "node_modules/pg-pool": {
+            "version": "3.11.0",
+            "resolved": "https://registry.npmjs.org/pg-pool/-/pg-pool-3.11.0.tgz",
+            "integrity": "sha512-MJYfvHwtGp870aeusDh+hg9apvOe2zmpZJpyt+BMtzUWlVqbhFmMK6bOBXLBUPd7iRtIF9fZplDc7KrPN3PN7w==",
+            "license": "MIT",
+            "peerDependencies": {
+                "pg": ">=8.0"
+            }
+        },
+        "node_modules/pg-protocol": {
+            "version": "1.11.0",
+            "resolved": "https://registry.npmjs.org/pg-protocol/-/pg-protocol-1.11.0.tgz",
+            "integrity": "sha512-pfsxk2M9M3BuGgDOfuy37VNRRX3jmKgMjcvAcWqNDpZSf4cUmv8HSOl5ViRQFsfARFn0KuUQTgLxVMbNq5NW3g==",
+            "license": "MIT"
+        },
+        "node_modules/pg-types": {
+            "version": "2.2.0",
+            "resolved": "https://registry.npmjs.org/pg-types/-/pg-types-2.2.0.tgz",
+            "integrity": "sha512-qTAAlrEsl8s4OiEQY69wDvcMIdQN6wdz5ojQiOy6YRMuynxenON0O5oCpJI6lshc6scgAY8qvJ2On/p+CXY0GA==",
+            "license": "MIT",
+            "dependencies": {
+                "pg-int8": "1.0.1",
+                "postgres-array": "~2.0.0",
+                "postgres-bytea": "~1.0.0",
+                "postgres-date": "~1.0.4",
+                "postgres-interval": "^1.1.0"
+            },
+            "engines": {
+                "node": ">=4"
+            }
+        },
+        "node_modules/pgpass": {
+            "version": "1.0.5",
+            "resolved": "https://registry.npmjs.org/pgpass/-/pgpass-1.0.5.tgz",
+            "integrity": "sha512-FdW9r/jQZhSeohs1Z3sI1yxFQNFvMcnmfuj4WBMUTxOrAyLMaTcE1aAMBiTlbMNaXvBCQuVi0R7hd8udDSP7ug==",
+            "license": "MIT",
+            "dependencies": {
+                "split2": "^4.1.0"
+            }
+        },
         "node_modules/picocolors": {
             "version": "1.1.1",
             "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
@@ -2222,6 +2437,54 @@
                 "node": "^10 || ^12 || >=14"
             }
         },
+        "node_modules/postgres-array": {
+            "version": "2.0.0",
+            "resolved": "https://registry.npmjs.org/postgres-array/-/postgres-array-2.0.0.tgz",
+            "integrity": "sha512-VpZrUqU5A69eQyW2c5CA1jtLecCsN2U/bD6VilrFDWq5+5UIEVO7nazS3TEcHf1zuPYO/sqGvUvW62g86RXZuA==",
+            "license": "MIT",
+            "engines": {
+                "node": ">=4"
+            }
+        },
+        "node_modules/postgres-bytea": {
+            "version": "1.0.1",
+            "resolved": "https://registry.npmjs.org/postgres-bytea/-/postgres-bytea-1.0.1.tgz",
+            "integrity": "sha512-5+5HqXnsZPE65IJZSMkZtURARZelel2oXUEO8rH83VS/hxH5vv1uHquPg5wZs8yMAfdv971IU+kcPUczi7NVBQ==",
+            "license": "MIT",
+            "engines": {
+                "node": ">=0.10.0"
+            }
+        },
+        "node_modules/postgres-date": {
+            "version": "1.0.7",
+            "resolved": "https://registry.npmjs.org/postgres-date/-/postgres-date-1.0.7.tgz",
+            "integrity": "sha512-suDmjLVQg78nMK2UZ454hAG+OAW+HQPZ6n++TNDUX+L0+uUlLywnoxJKDou51Zm+zTCjrCl0Nq6J9C5hP9vK/Q==",
+            "license": "MIT",
+            "engines": {
+                "node": ">=0.10.0"
+            }
+        },
+        "node_modules/postgres-interval": {
+            "version": "1.2.0",
+            "resolved": "https://registry.npmjs.org/postgres-interval/-/postgres-interval-1.2.0.tgz",
+            "integrity": "sha512-9ZhXKM/rw350N1ovuWHbGxnGh/SNJ4cnxHiM0rxE4VN41wsg8P8zWn9hv/buK00RP4WvlOyr/RBDiptyxVbkZQ==",
+            "license": "MIT",
+            "dependencies": {
+                "xtend": "^4.0.0"
+            },
+            "engines": {
+                "node": ">=0.10.0"
+            }
+        },
+        "node_modules/process": {
+            "version": "0.11.10",
+            "resolved": "https://registry.npmjs.org/process/-/process-0.11.10.tgz",
+            "integrity": "sha512-cdGef/drWFoydD1JsMzuFf8100nZl+GT+yacc2bEced5f9Rjk4z+WtFUTBu9PhOi9j/jfmBPu0mMEY4wIdAF8A==",
+            "license": "MIT",
+            "engines": {
+                "node": ">= 0.6.0"
+            }
+        },
         "node_modules/proxy-addr": {
             "version": "2.0.7",
             "resolved": "https://registry.npmjs.org/proxy-addr/-/proxy-addr-2.0.7.tgz",
@@ -2281,6 +2544,22 @@
                 "node": ">= 0.8"
             }
         },
+        "node_modules/readable-stream": {
+            "version": "4.7.0",
+            "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-4.7.0.tgz",
+            "integrity": "sha512-oIGGmcpTLwPga8Bn6/Z75SVaH1z5dUut2ibSyAMVhmUggWpmDn2dapB0n7f8nwaSiRtepAsfJyfXIO5DCVAODg==",
+            "license": "MIT",
+            "dependencies": {
+                "abort-controller": "^3.0.0",
+                "buffer": "^6.0.3",
+                "events": "^3.3.0",
+                "process": "^0.11.10",
+                "string_decoder": "^1.3.0"
+            },
+            "engines": {
+                "node": "^12.22.0 || ^14.17.0 || >=16.0.0"
+            }
+        },
         "node_modules/readdirp": {
             "version": "3.6.0",
             "resolved": "https://registry.npmjs.org/readdirp/-/readdirp-3.6.0.tgz",
@@ -2531,6 +2810,15 @@
                 "node": ">=0.10.0"
             }
         },
+        "node_modules/split2": {
+            "version": "4.2.0",
+            "resolved": "https://registry.npmjs.org/split2/-/split2-4.2.0.tgz",
+            "integrity": "sha512-UcjcJOWknrNkF6PLX83qcHM6KHgVKNkV62Y8a5uYDVv9ydGQVwAHMKqHdJje1VTWpljG0WYpCDhrCdAOYH4TWg==",
+            "license": "ISC",
+            "engines": {
+                "node": ">= 10.x"
+            }
+        },
         "node_modules/stackback": {
             "version": "0.0.2",
             "resolved": "https://registry.npmjs.org/stackback/-/stackback-0.0.2.tgz",
@@ -2554,6 +2842,15 @@
             "dev": true,
             "license": "MIT"
         },
+        "node_modules/string_decoder": {
+            "version": "1.3.0",
+            "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.3.0.tgz",
+            "integrity": "sha512-hkRX8U1WjJFd8LsDJ2yQ/wWWxaopEsABU1XfkM8A+j0+85JAGppt16cr1Whg6KIbb4okU6Mql6BOj+uup/wKeA==",
+            "license": "MIT",
+            "dependencies": {
+                "safe-buffer": "~5.2.0"
+            }
+        },
         "node_modules/superagent": {
             "version": "10.3.0",
             "resolved": "https://registry.npmjs.org/superagent/-/superagent-10.3.0.tgz",
@@ -2759,6 +3056,12 @@
                 "nodetouch": "bin/nodetouch.js"
             }
         },
+        "node_modules/tr46": {
+            "version": "0.0.3",
+            "resolved": "https://registry.npmjs.org/tr46/-/tr46-0.0.3.tgz",
+            "integrity": "sha512-N3WMsuqV66lT30CrXNbEjx4GEwlow3v6rr4mCcv6prnfwhS01rkgyFdjPNBYd9br7LpXV1+Emh01fHnq2Gdgrw==",
+            "license": "MIT"
+        },
         "node_modules/ts-algebra": {
             "version": "2.0.0",
             "resolved": "https://registry.npmjs.org/ts-algebra/-/ts-algebra-2.0.0.tgz",
@@ -2794,6 +3097,12 @@
                 "node": ">= 0.8"
             }
         },
+        "node_modules/url-join": {
+            "version": "4.0.1",
+            "resolved": "https://registry.npmjs.org/url-join/-/url-join-4.0.1.tgz",
+            "integrity": "sha512-jk1+QP6ZJqyOiuEI9AEWQfju/nB2Pw466kbA0LEZljHwKeMgd9WrAEgEGxjPDD2+TNbbb37rTyhEfrCXfuKXnA==",
+            "license": "MIT"
+        },
         "node_modules/utils-merge": {
             "version": "1.0.1",
             "resolved": "https://registry.npmjs.org/utils-merge/-/utils-merge-1.0.1.tgz",
@@ -3011,6 +3320,52 @@
                 "url": "https://github.com/sponsors/jonschlinkert"
             }
         },
+        "node_modules/voyageai": {
+            "version": "0.1.0",
+            "resolved": "https://registry.npmjs.org/voyageai/-/voyageai-0.1.0.tgz",
+            "integrity": "sha512-QnalSSHRigZqzKJpXLsgp3tKaKkSv2kGO4rcXQ6mr6PKHa0vRirs0jZ72olvFJrGJkbu1hHijcyr6/eI4L5aRw==",
+            "license": "MIT",
+            "dependencies": {
+                "form-data": "^4.0.0",
+                "formdata-node": "^6.0.3",
+                "js-base64": "3.7.2",
+                "node-fetch": "2.7.0",
+                "qs": "6.11.2",
+                "readable-stream": "^4.5.2",
+                "url-join": "4.0.1"
+            }
+        },
+        "node_modules/voyageai/node_modules/qs": {
+            "version": "6.11.2",
+            "resolved": "https://registry.npmjs.org/qs/-/qs-6.11.2.tgz",
+            "integrity": "sha512-tDNIz22aBzCDxLtVH++VnTfzxlfeK5CbqohpSqpJgj1Wg/cQbStNAz3NuqCs5vV+pjBsK4x4pN9HlVh7rcYRiA==",
+            "license": "BSD-3-Clause",
+            "dependencies": {
+                "side-channel": "^1.0.4"
+            },
+            "engines": {
+                "node": ">=0.6"
+            },
+            "funding": {
+                "url": "https://github.com/sponsors/ljharb"
+            }
+        },
+        "node_modules/webidl-conversions": {
+            "version": "3.0.1",
+            "resolved": "https://registry.npmjs.org/webidl-conversions/-/webidl-conversions-3.0.1.tgz",
+            "integrity": "sha512-2JAn3z8AR6rjK8Sm8orRC0h/bcl/DqL7tRPdGZ4I1CjdF+EaMLmYxBHyXuKL849eucPFhvBoxMsflfOb8kxaeQ==",
+            "license": "BSD-2-Clause"
+        },
+        "node_modules/whatwg-url": {
+            "version": "5.0.0",
+            "resolved": "https://registry.npmjs.org/whatwg-url/-/whatwg-url-5.0.0.tgz",
+            "integrity": "sha512-saE57nupxk6v3HY35+jzBwYa0rKSy0XR8JSxZPwgLr7ys0IBzhGviA1/TUGJLmSVqs8pb9AnvICXEuOHLprYTw==",
+            "license": "MIT",
+            "dependencies": {
+                "tr46": "~0.0.3",
+                "webidl-conversions": "^3.0.0"
+            }
+        },
         "node_modules/why-is-node-running": {
             "version": "2.3.0",
             "resolved": "https://registry.npmjs.org/why-is-node-running/-/why-is-node-running-2.3.0.tgz",
@@ -3034,6 +3389,15 @@
             "integrity": "sha512-l4Sp/DRseor9wL6EvV2+TuQn63dMkPjZ/sp9XkghTEbV9KlPS1xUsZ3u7/IQO4wxtcFB4bgpQPRcR3QCvezPcQ==",
             "dev": true,
             "license": "ISC"
+        },
+        "node_modules/xtend": {
+            "version": "4.0.2",
+            "resolved": "https://registry.npmjs.org/xtend/-/xtend-4.0.2.tgz",
+            "integrity": "sha512-LKYU1iAXJXUgAXn9URjiu+MWhyUXHsvfp7mcuYm9dSUKK0/CjtrUwFAxD82/mCWbtLsGjFIad0wIsod4zrTAEQ==",
+            "license": "MIT",
+            "engines": {
+                "node": ">=0.4"
+            }
         }
     }
 }

backend/package.json

@@ -7,13 +7,17 @@
     "scripts": {
         "start": "node server.js",
         "dev": "nodemon server.js",
-        "test": "vitest run"
+        "test": "vitest run",
+        "db:migrate": "node db/migrate.js",
+        "db:seed": "node db/seed.js"
     },
     "dependencies": {
         "@anthropic-ai/sdk": "^0.74.0",
         "cors": "^2.8.5",
         "dotenv": "^16.4.7",
-        "express": "^4.21.2"
+        "express": "^4.21.2",
+        "pg": "^8.18.0",
+        "voyageai": "^0.1.0"
     },
     "devDependencies": {
         "nodemon": "^3.1.9",

backend/routes/notes.routes.js

@@ -1,18 +1,12 @@
 import { Router } from 'express';
-import { readFile } from 'fs/promises';
+import { getAllNotes } from '../db/notes.dao.js';
 import { clusterNotes } from '../services/clustering.service.js';
 
 const router = Router();
-const DATA_PATH = '../data/notes.json';
-
-const loadNotes = async () => {
-  const raw = await readFile(DATA_PATH, 'utf-8');
-  return JSON.parse(raw);
-};
 
 router.get('/', async (req, res) => {
   try {
-    const notes = await loadNotes();
+    const notes = await getAllNotes();
     res.json(notes);
   } catch (err) {
     console.error(`Error loading notes: ${err}`);
@@ -22,12 +16,12 @@ router.get('/', async (req, res) => {
 
 router.post('/cluster', async (req, res) => {
   try {
-    const notes = await loadNotes();
+    const notes = await getAllNotes();
-    const clusters = await clusterNotes(notes);
+    const result = await clusterNotes(notes);
-    res.json(clusters);
+    res.json(result);
   } catch (err) {
     console.error(`Clustering failed: ${err}`);
-    res.status(500).json({ error: `Clustering failed: ${err}` });
+    res.status(500).json({ error: 'Clustering failed' });
   }
 });
 

backend/services/clustering.service.js

@@ -1,4 +1,6 @@
 import Anthropic from "@anthropic-ai/sdk";
+import { embedNotes } from "./embedding.service.js";
+import { validateStructure, computeCohesionScore } from "./validation.service.js";
 
 const client = new Anthropic({
   apiKey: process.env.ANTHROPIC_API_KEY,
@@ -31,17 +33,17 @@ Here are the notes:
 ${notesJson}`;
 };
 
-export const clusterNotes = async (notes) => {
+const requestClusters = async (notes) => {
   const response = await client.messages.create({
-   model: "claude-sonnet-4-20250514",
+    model: "claude-sonnet-4-20250514",
-   max_tokens: 4096,
+    max_tokens: 4096,
-   messages: [
+    messages: [
       { role: "user", content: buildPrompt(notes) },
-   ],
+    ],
   });
 
   const textBlock = response?.content?.[0];
-  
+
   if (!textBlock || textBlock.type !== 'text' || typeof textBlock.text !== 'string') {
     throw new Error('Unexpected response from LLM API: no text content returned');
   }
@@ -52,3 +54,20 @@ export const clusterNotes = async (notes) => {
     throw new Error('LLM API returned non-JSON response');
   }
 };
+
+export const clusterNotes = async (notes) => {
+  const [clusters, embeddingMap] = await Promise.all([
+    requestClusters(notes),
+    embedNotes(notes),
+  ]);
+
+  const noteIds = notes.map((n) => n.id);
+  const { valid, reasons } = validateStructure(clusters, noteIds);
+  if (!valid) {
+    throw new Error(`Cluster validation failed: ${reasons.join('; ')}`);
+  }
+
+  const score = computeCohesionScore(clusters, embeddingMap);
+
+  return { clusters, score: Math.round(score * 100) / 100 };
+};

backend/services/embedding.service.js

@@ -0,0 +1,25 @@
+import { VoyageAIClient } from "voyageai";
+
+const client = new VoyageAIClient({
+  apiKey: process.env.VOYAGEAI_API_KEY,
+});
+
+/**
+ * @param {Array<{id: string, text: string}>} notes
+ * @returns {Promise<Map<string, number[]>>} noteId → embedding vector
+ */
+export const embedNotes = async (notes) => {
+  const texts = notes.map((n) => n.text);
+
+  const response = await client.embed({
+    input: texts,
+    model: "voyage-3-lite",
+  });
+
+  const embeddingMap = new Map();
+  response.data.forEach((item, i) => {
+    embeddingMap.set(notes[i].id, item.embedding);
+  });
+
+  return embeddingMap;
+};

backend/services/validation.service.js

@@ -0,0 +1,129 @@
+/**
+ * Structural validation: confirms the LLM output is well-formed
+ * before it reaches the frontend.
+ *
+ * @param {Array<{label: string, noteIds: string[]}>} clusters
+ * @param {string[]} inputNoteIds - the original note IDs that were sent to the LLM
+ * @returns {{valid: boolean, reasons: string[]}}
+ */
+export const validateStructure = (clusters, inputNoteIds) => {
+  const reasons = [];
+
+  if (!Array.isArray(clusters) || clusters.length === 0) {
+    return { valid: false, reasons: ['Response is not a non-empty array'] };
+  }
+
+  const assignedIds = [];
+  for (const cluster of clusters) {
+    if (!cluster.label || typeof cluster.label !== 'string') {
+      reasons.push(`Cluster missing a valid label`);
+    }
+    if (!Array.isArray(cluster.noteIds) || cluster.noteIds.length === 0) {
+      reasons.push(`Cluster "${cluster.label ?? '(unlabeled)'}" has no noteIds`);
+    }
+    assignedIds.push(...(cluster.noteIds ?? []));
+  }
+
+  const inputSet = new Set(inputNoteIds);
+  const assignedSet = new Set(assignedIds);
+
+  if (assignedIds.length !== assignedSet.size) {
+    reasons.push('One or more notes appear in multiple clusters');
+  }
+
+  const missing = inputNoteIds.filter((id) => !assignedSet.has(id));
+  if (missing.length > 0) {
+    reasons.push(`Notes missing from clusters: ${missing.join(', ')}`);
+  }
+
+  const extra = assignedIds.filter((id) => !inputSet.has(id));
+  if (extra.length > 0) {
+    reasons.push(`Unknown noteIds in clusters: ${[...new Set(extra)].join(', ')}`);
+  }
+
+  if (clusters.length > inputNoteIds.length) {
+    reasons.push(`More clusters (${clusters.length}) than notes (${inputNoteIds.length})`);
+  }
+
+  return { valid: reasons.length === 0, reasons };
+};
+
+const cosineSimilarity = (a, b) => {
+  let dot = 0;
+  let magA = 0;
+  let magB = 0;
+  for (let i = 0; i < a.length; i++) {
+    dot += a[i] * b[i];
+    magA += a[i] * a[i];
+    magB += b[i] * b[i];
+  }
+  const denom = Math.sqrt(magA) * Math.sqrt(magB);
+  return denom === 0 ? 0 : dot / denom;
+};
+
+/**
+ * Computes a silhouette-style cohesion score for the clustering.
+ *
+ * For each note, measures how much more similar it is to its own cluster
+ * versus the nearest neighboring cluster. Returns a score in [-1, 1]
+ * where higher is better.
+ *
+ * @param {Array<{label: string, noteIds: string[]}>} clusters
+ * @param {Map<string, number[]>} embeddingMap - noteId → vector
+ * @returns {number} average silhouette score
+ */
+export const computeCohesionScore = (clusters, embeddingMap) => {
+  if (clusters.length <= 1) return 1.0;
+
+  const scores = [];
+
+  for (let ci = 0; ci < clusters.length; ci++) {
+    const clusterIds = clusters[ci].noteIds;
+    if (clusterIds.length <= 1) {
+      scores.push(0);
+      continue;
+    }
+
+    for (const noteId of clusterIds) {
+      const vec = embeddingMap.get(noteId);
+      if (!vec) continue;
+
+      // a(i): avg distance to other notes in same cluster
+      let intraSum = 0;
+      let intraCount = 0;
+      for (const otherId of clusterIds) {
+        if (otherId === noteId) continue;
+        const otherVec = embeddingMap.get(otherId);
+        if (!otherVec) continue;
+        intraSum += 1 - cosineSimilarity(vec, otherVec);
+        intraCount++;
+      }
+      const a = intraCount > 0 ? intraSum / intraCount : 0;
+
+      // b(i): min avg distance to notes in any other cluster
+      let b = Infinity;
+      for (let oi = 0; oi < clusters.length; oi++) {
+        if (oi === ci) continue;
+        const otherClusterIds = clusters[oi].noteIds;
+        let interSum = 0;
+        let interCount = 0;
+        for (const otherId of otherClusterIds) {
+          const otherVec = embeddingMap.get(otherId);
+          if (!otherVec) continue;
+          interSum += 1 - cosineSimilarity(vec, otherVec);
+          interCount++;
+        }
+        if (interCount > 0) {
+          b = Math.min(b, interSum / interCount);
+        }
+      }
+      if (b === Infinity) b = 0;
+
+      const max = Math.max(a, b);
+      scores.push(max === 0 ? 0 : (b - a) / max);
+    }
+  }
+
+  if (scores.length === 0) return 0;
+  return scores.reduce((sum, s) => sum + s, 0) / scores.length;
+};

backend/tests/Clustering.service.test.js

@@ -1,7 +1,11 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 
-const { createMock } = vi.hoisted(() => {
+const { createMock, mockEmbeddings } = vi.hoisted(() => {
-  return { createMock: vi.fn() };
+  const embeddings = new Map([
+    ['note_001', [1.0, 0.0, 0.0]],
+    ['note_002', [0.0, 1.0, 0.0]],
+  ]);
+  return { createMock: vi.fn(), mockEmbeddings: embeddings };
 });
 
 vi.mock('@anthropic-ai/sdk', () => {
@@ -14,6 +18,10 @@ vi.mock('@anthropic-ai/sdk', () => {
   };
 });
 
+vi.mock('../services/embedding.service.js', () => ({
+  embedNotes: vi.fn().mockResolvedValue(mockEmbeddings),
+}));
+
 import { clusterNotes } from '../services/clustering.service.js';
 
 const MOCK_NOTES = [
@@ -60,14 +68,17 @@ describe('clusterNotes service', () => {
     expect(prompt).toContain('Export fails');
   });
 
-  it('should parse and return the clustered JSON from the API response', async () => {
+  it('should return clusters and a cohesion score', async () => {
     createMock.mockResolvedValue({
       content: [{ type: 'text', text: JSON.stringify(MOCK_CLUSTERS) }],
     });
 
     const result = await clusterNotes(MOCK_NOTES);
 
-    expect(result).toEqual(MOCK_CLUSTERS);
+    expect(result.clusters).toEqual(MOCK_CLUSTERS);
+    expect(typeof result.score).toBe('number');
+    expect(result.score).toBeGreaterThanOrEqual(-1);
+    expect(result.score).toBeLessThanOrEqual(1);
   });
 
   it('should throw error when the API returns non-JSON', async () => {
@@ -89,4 +100,15 @@ describe('clusterNotes service', () => {
 
     await expect(clusterNotes(MOCK_NOTES)).rejects.toThrow('401 Unauthorized');
   });
+
+  it('should throw a validation error when a note is missing from clusters', async () => {
+    const incompleteClusters = [
+      { label: 'Auth Issues', noteIds: ['note_001'] },
+    ];
+    createMock.mockResolvedValue({
+      content: [{ type: 'text', text: JSON.stringify(incompleteClusters) }],
+    });
+
+    await expect(clusterNotes(MOCK_NOTES)).rejects.toThrow('Cluster validation failed');
+  });
 });

backend/tests/Notes.test.js

@@ -2,16 +2,16 @@ import { describe, it, expect, vi, beforeEach } from 'vitest';
 import request from 'supertest';
 import app from '../app.js';
 
+vi.mock('../db/notes.dao.js', () => ({
+  getAllNotes: vi.fn(),
+}));
+
 vi.mock('../services/clustering.service.js', () => ({
   clusterNotes: vi.fn(),
 }));
 
-vi.mock('fs/promises', () => ({
+import { getAllNotes } from '../db/notes.dao.js';
-  readFile: vi.fn(),
-}));
-
 import { clusterNotes } from '../services/clustering.service.js';
-import { readFile } from 'fs/promises';
 
 const MOCK_NOTES = [
   { id: 'note_001', text: 'Login flow feels confusing', x: 193, y: 191, author: 'user_5', color: 'yellow' },
@@ -31,7 +31,7 @@ describe('GET /v1/notes', () => {
   });
 
   it('should return 200 and an array of notes', async () => {
-    readFile.mockResolvedValue(JSON.stringify(MOCK_NOTES));
+    getAllNotes.mockResolvedValue(MOCK_NOTES);
 
     const res = await request(app).get('/v1/notes');
 
@@ -41,7 +41,7 @@ describe('GET /v1/notes', () => {
   });
 
   it('should return notes with expected properties', async () => {
-    readFile.mockResolvedValue(JSON.stringify(MOCK_NOTES));
+    getAllNotes.mockResolvedValue(MOCK_NOTES);
 
     const res = await request(app).get('/v1/notes');
     const note = res.body[0];
@@ -54,8 +54,8 @@ describe('GET /v1/notes', () => {
     expect(note).toHaveProperty('color');
   });
 
-  it('should return 500 when the data file cannot be read', async () => {
+  it('should return 500 when the database query fails', async () => {
-    readFile.mockRejectedValue(new Error('ENOENT: file not found'));
+    getAllNotes.mockRejectedValue(new Error('connection refused'));
 
     const res = await request(app).get('/v1/notes');
 
@@ -63,15 +63,6 @@ describe('GET /v1/notes', () => {
     expect(res.body).toHaveProperty('error');
     expect(res.body.error).toBe('Failed to load notes');
   });
-
-  it('should return 500 when data file is invalid JSON', async () => {
-    readFile.mockResolvedValue('{ this is not valid json }');
-
-    const res = await request(app).get('/v1/notes');
-
-    expect(res.status).toBe(500);
-    expect(res.body).toHaveProperty('error');
-  });
 });
 
 describe('POST /v1/notes/cluster', () => {
@@ -81,7 +72,7 @@ describe('POST /v1/notes/cluster', () => {
   });
 
   it('should return 200 and clustered results', async () => {
-    readFile.mockResolvedValue(JSON.stringify(MOCK_NOTES));
+    getAllNotes.mockResolvedValue(MOCK_NOTES);
     clusterNotes.mockResolvedValue(MOCK_CLUSTERS);
 
     const res = await request(app).post('/v1/notes/cluster');
@@ -91,7 +82,7 @@ describe('POST /v1/notes/cluster', () => {
   });
 
   it('should return clusters with the expected shape (label, noteIds)', async () => {
-    readFile.mockResolvedValue(JSON.stringify(MOCK_NOTES));
+    getAllNotes.mockResolvedValue(MOCK_NOTES);
     clusterNotes.mockResolvedValue(MOCK_CLUSTERS);
 
     const res = await request(app).post('/v1/notes/cluster');
@@ -104,7 +95,7 @@ describe('POST /v1/notes/cluster', () => {
   });
 
   it('should pass the loaded notes to clusterNotes', async () => {
-    readFile.mockResolvedValue(JSON.stringify(MOCK_NOTES));
+    getAllNotes.mockResolvedValue(MOCK_NOTES);
     clusterNotes.mockResolvedValue(MOCK_CLUSTERS);
 
     await request(app).post('/v1/notes/cluster');
@@ -114,8 +105,8 @@ describe('POST /v1/notes/cluster', () => {
   });
 
   it('should return 500 when clusterNotes (API call) fails', async () => {
-    readFile.mockResolvedValue(JSON.stringify(MOCK_NOTES));
+    getAllNotes.mockResolvedValue(MOCK_NOTES);
-    clusterNotes.mockRejectedValue(new Error('Anthropic API error'));
+    clusterNotes.mockRejectedValue(new Error('LLM API error'));
 
     const res = await request(app).post('/v1/notes/cluster');
 
@@ -124,12 +115,12 @@ describe('POST /v1/notes/cluster', () => {
     expect(res.body.error).toMatch(/^Clustering failed/);
   });
 
-  it('should return 500 when the data file cannot be read', async () => {
+  it('should return 500 when the database query fails', async () => {
-    readFile.mockRejectedValue(new Error('ENOENT: file not found'));
+    getAllNotes.mockRejectedValue(new Error('connection refused'));
 
     const res = await request(app).post('/v1/notes/cluster');
 
     expect(res.status).toBe(500);
     expect(res.body).toHaveProperty('error');
   });
-});
+});

backend/tests/notes.dao.test.js

@@ -0,0 +1,113 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+const { mockQuery } = vi.hoisted(() => ({
+  mockQuery: vi.fn(),
+}));
+
+vi.mock('../db/index.js', () => ({
+  query: mockQuery,
+}));
+
+import { getAllNotes, getNoteById, createNote, createNotes } from '../db/notes.dao.js';
+
+const MOCK_ROWS = [
+  { id: 'note_001', text: 'Login flow feels confusing', x: 193, y: 191, author: 'user_5', color: 'yellow' },
+  { id: 'note_002', text: 'Login flow is broken on mobile', x: 214, y: 281, author: 'user_9', color: 'yellow' },
+];
+
+describe('notes.dao', () => {
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  describe('getAllNotes', () => {
+    it('should return all notes ordered by id', async () => {
+      mockQuery.mockResolvedValue({ rows: MOCK_ROWS });
+
+      const result = await getAllNotes();
+
+      expect(result).toEqual(MOCK_ROWS);
+      expect(mockQuery).toHaveBeenCalledWith(
+        'SELECT id, text, x, y, author, color FROM notes ORDER BY id'
+      );
+    });
+
+    it('should return an empty array when no notes exist', async () => {
+      mockQuery.mockResolvedValue({ rows: [] });
+
+      const result = await getAllNotes();
+
+      expect(result).toEqual([]);
+    });
+
+    it('should propagate database errors', async () => {
+      mockQuery.mockRejectedValue(new Error('connection refused'));
+
+      await expect(getAllNotes()).rejects.toThrow('connection refused');
+    });
+  });
+
+  describe('getNoteById', () => {
+    it('should return a single note when found', async () => {
+      mockQuery.mockResolvedValue({ rows: [MOCK_ROWS[0]] });
+
+      const result = await getNoteById('note_001');
+
+      expect(result).toEqual(MOCK_ROWS[0]);
+      expect(mockQuery).toHaveBeenCalledWith(
+        'SELECT id, text, x, y, author, color FROM notes WHERE id = $1',
+        ['note_001']
+      );
+    });
+
+    it('should return null when note is not found', async () => {
+      mockQuery.mockResolvedValue({ rows: [] });
+
+      const result = await getNoteById('note_999');
+
+      expect(result).toBeNull();
+    });
+  });
+
+  describe('createNote', () => {
+    it('should insert a note and return it', async () => {
+      const input = { id: 'note_003', text: 'Export fails', x: 100, y: 200, author: 'user_1', color: 'blue' };
+      mockQuery.mockResolvedValue({ rows: [input] });
+
+      const result = await createNote(input);
+
+      expect(result).toEqual(input);
+      expect(mockQuery).toHaveBeenCalledOnce();
+      const [sql, params] = mockQuery.mock.calls[0];
+      expect(sql).toContain('INSERT INTO notes');
+      expect(params).toEqual(['note_003', 'Export fails', 100, 200, 'user_1', 'blue']);
+    });
+
+    it('should use defaults for missing x, y, and color', async () => {
+      const input = { id: 'note_004', text: 'Needs fixing', author: 'user_2' };
+      mockQuery.mockResolvedValue({ rows: [{ ...input, x: 0, y: 0, color: 'yellow' }] });
+
+      await createNote(input);
+
+      const params = mockQuery.mock.calls[0][1];
+      expect(params[2]).toBe(0);
+      expect(params[3]).toBe(0);
+      expect(params[5]).toBe('yellow');
+    });
+  });
+
+  describe('createNotes', () => {
+    it('should batch-insert multiple notes and return them', async () => {
+      mockQuery.mockResolvedValue({ rows: MOCK_ROWS });
+
+      const result = await createNotes(MOCK_ROWS);
+
+      expect(result).toEqual(MOCK_ROWS);
+      expect(mockQuery).toHaveBeenCalledOnce();
+      const [sql, params] = mockQuery.mock.calls[0];
+      expect(sql).toContain('INSERT INTO notes');
+      expect(params).toHaveLength(12);
+    });
+  });
+});

frontend/.env.development

@@ -0,0 +1,2 @@
+VITE_APP_URL=localhost:3000
+VITE_API_BASE=http://localhost:3001

frontend/.env.production

@@ -0,0 +1,2 @@
+VITE_APP_URL=https://example.com
+VITE_API_BASE=https://www.example.com:4000

frontend/src/api/api.ts

@@ -1,7 +1,7 @@
 import { useQuery, useMutation } from '@tanstack/react-query';
-import type { Sticky, Cluster } from '../types/types';
+import type { Sticky, ClusterResponse } from '../types/types';
 
-const API_BASE = 'http://localhost:3001/v1/notes';
+const API_BASE = `${import.meta.env.VITE_API_BASE}/v1/notes`;
 
 const fetchStickies = async (): Promise<Sticky[]> => {
   const response = await fetch(API_BASE);
@@ -11,7 +11,7 @@ const fetchStickies = async (): Promise<Sticky[]> => {
   return response.json();
 };
 
-const fetchClusters = async (): Promise<Cluster[]> => {
+const fetchClusters = async (): Promise<ClusterResponse> => {
   const response = await fetch(`${API_BASE}/cluster`, {
     method: 'POST',
   });
@@ -29,7 +29,7 @@ export const useGetStickies = () => {
 };
 
 export const useClusterStickies = () => {
-  return useMutation<Cluster[]>({
+  return useMutation<ClusterResponse>({
     mutationFn: fetchClusters,
   });
 };

frontend/src/components/button.tsx

@@ -8,9 +8,9 @@ type ButtonProps = {
 
 const Button = ({ onClick, isLoading, label }: ButtonProps) => {
   return (
-      <button className="primaryButton" onClick={onClick} disabled={isLoading}>
+    <button className="primaryButton" onClick={onClick} disabled={isLoading}>
-         {isLoading ? 'Working...' : label}
+      {isLoading ? 'Working...' : label}
-      </button>
+    </button>
   );
 };
 

frontend/src/components/navbar.tsx

@@ -1,14 +1,14 @@
 const Navbar = () => {
-   return (
+  return (
-      <div className="main-head-box">
+    <div className="main-head-box">
-         <div className="main-head-subbox-left">
+      <div className="main-head-subbox-left">
-            <h1 className="main-head">kongruity</h1>
+        <h1 className="main-head">kongruity</h1>
-         </div>
-         <div className="main-head-subbox-right">
-            <span className="material-symbols-outlined">recenter</span>
-         </div>
       </div>
-   )
+      <div className="main-head-subbox-right">
+        <span className="material-symbols-outlined">recenter</span>
+      </div>
+    </div>
+  )
 }
 
-export default Navbar;
+export default Navbar;

frontend/src/components/stickies.tsx

@@ -1,16 +1,39 @@
+import { useState, useEffect, useRef } from 'react';
+import type { DragEvent } from 'react';
 import { useGetStickies, useClusterStickies } from '../api/api';
-import type { Sticky as StickyType } from '../types/types';
+import type { Sticky as StickyType, RankedCluster } from '../types/types';
 import Sticky from './sticky';
 import Button from './button';
 import '../styles/stickies.css';
 
+const scoreLabel = (score: number): string => {
+  if (score >= 0.7) return 'Strong';
+  if (score >= 0.4) return 'Moderate';
+  if (score >= 0.1) return 'Weak';
+  return 'Poor';
+};
+
 const Stickies = () => {
   const { data: stickies, isLoading, error } = useGetStickies();
-  const { mutate: cluster, data: clusters, isPending } = useClusterStickies();
+  const { mutate: cluster, data: clusterResponse, isPending } = useClusterStickies();
+
+  const [rankedClusters, setRankedClusters] = useState<RankedCluster[]>([]);
+  const dragIndex = useRef<number | null>(null);
+  const [dragOverIndex, setDragOverIndex] = useState<number | null>(null);
+
+  useEffect(() => {
+    if (clusterResponse?.clusters) {
+      setRankedClusters(
+        clusterResponse.clusters.map((c, i) => ({ ...c, rank: i + 1 }))
+      );
+    }
+  }, [clusterResponse]);
 
   if (isLoading) return <div>Loading...</div>;
   if (error) return <div>Error: {error.message}</div>;
 
+  const score = clusterResponse?.score;
+
   const handleCluster = () => {
     cluster();
   };
@@ -24,20 +47,75 @@ const Stickies = () => {
   const stickyMap = buildStickyMap();
 
   const renderStickies = (items: StickyType[]) =>
-    items.map((sticky) => <Sticky key={sticky.id} sticky={sticky} />);
+    items?.map((sticky) => <Sticky key={sticky.id} sticky={sticky} />);
+
+  const handleDragStart = (index: number) => {
+    dragIndex.current = index;
+  };
+
+  const handleDragOver = (e: DragEvent, index: number) => {
+    e.preventDefault();
+    setDragOverIndex(index);
+  };
+
+  const handleDragLeave = () => {
+    setDragOverIndex(null);
+  };
+
+  const handleDrop = (targetIndex: number) => {
+    const sourceIndex = dragIndex.current;
+    if (sourceIndex === null || sourceIndex === targetIndex) {
+      dragIndex.current = null;
+      setDragOverIndex(null);
+      return;
+    }
+
+    const reordered = [...rankedClusters];
+    const [moved] = reordered.splice(sourceIndex, 1);
+    reordered.splice(targetIndex, 0, moved);
+
+    setRankedClusters(reordered.map((c, i) => ({ ...c, rank: i + 1 })));
+    dragIndex.current = null;
+    setDragOverIndex(null);
+  };
+
+  const handleDragEnd = () => {
+    dragIndex.current = null;
+    setDragOverIndex(null);
+  };
 
   return (
     <div className="stickies-container">
       <Button onClick={handleCluster} isLoading={isPending} label="Group Stickies By Topic" />
-      {clusters ? (
+      {rankedClusters.length > 0 ? (
         <div className="clusters-container">
-          {clusters.map((group) => (
+          {score != null && (
-            <div key={group.label} className="cluster-group">
+            <div className="cohesion-score">
-              <h3 className="cluster-label">{group.label}</h3>
+              Cluster cohesion: <strong>{score.toFixed(2)}</strong> — {scoreLabel(score)}
+            </div>
+          )}
+          {rankedClusters.map((group, index) => (
+            <div
+              key={group.label}
+              className={`cluster-group cluster-draggable${dragOverIndex === index ? ' cluster-drag-over' : ''}`}
+              draggable
+              onDragStart={() => handleDragStart(index)}
+              onDragOver={(e) => handleDragOver(e, index)}
+              onDragLeave={handleDragLeave}
+              onDrop={() => handleDrop(index)}
+              onDragEnd={handleDragEnd}
+            >
+              <div className="cluster-header">
+                <span className="cluster-rank" aria-label={`Priority ${group.rank}`}>
+                  {group.rank}
+                </span>
+                <h3 className="cluster-label">{group.label}</h3>
+                <span className="cluster-drag-handle" aria-hidden="true">⠿</span>
+              </div>
               <div className="stickies-grid">
                 {renderStickies(
-                  group.noteIds
+                  group?.noteIds
-                    .map((id) => stickyMap.get(id))
+                    .map((id) => stickyMap?.get(id))
                     .filter((s): s is StickyType => !!s)
                 )}
               </div>

frontend/src/main.tsx

@@ -14,5 +14,5 @@ createRoot(document.getElementById('root')!).render(
         <App />
       </BrowserRouter>
     </QueryClientProvider>
-  </StrictMode>,
+  </StrictMode>
 )

frontend/src/pages/Home.tsx

@@ -3,16 +3,12 @@ import Navbar from '../components/navbar'
 import '../styles/home.css'
 
 const Home = () => {
-   return (
+  return (
-      <div>
+    <div>
-         <div>
+      <Navbar />
-            <Navbar />
+      <Stickies />
-         </div>
+    </div>
-         <div>
+  );
-            <Stickies />
-         </div>
-      </div>
-   );
 };
 
-export default Home;
+export default Home;

frontend/src/styles/home.css

@@ -1,41 +1,73 @@
 .main-head-box {
-    border-radius: 8px;
+  border-radius: 8px;
-    border: 1px solid #6dd6f4;
+  border: 1px solid #6dd6f4;
-    background-color: rgb(92, 0 91);
+  background-color: rgb(92, 0, 91);
-    display: flex;
+  display: flex;
-  }
+}
-  
+
+.main-head-subbox-right {
+  display: flex;
+  justify-content: flex-end;
+  margin-right: 34px;
+  width: 50%;
+}
+
+.main-head-subbox-left {
+  display: flex;
+  justify-content: flex-start;
+  margin-left: 34px;
+  width: 50%;
+}
+
+.main-head {
+  font-size: 5rem;
+  color: #6dd6f4;
+  margin: 6px 0px 24px 22px;
+  font-family: "Sulphur Point", sans-serif;
+  font-weight: 500;
+  letter-spacing: 4px;
+  text-decoration: underline;
+}
+
+.material-symbols-outlined {
+  margin: 13px 74px 0px 0px;
+  font-size: 82px;
+  color: #6dd6f4;
+  font-variation-settings:
+    'FILL' 0,
+    'wght' 300,
+    'GRAD' 0,
+    'opsz' 24;
+}
+
+@media screen and (max-width: 478px) {
   .main-head-subbox-right {
-    display: flex;
+    display: none;
-    justify-content: flex-end;
-    margin-right: 34px;
-    width: 50%;
   }
 
   .main-head-subbox-left {
     display: flex;
-    justify-content: flex-start;
+    justify-content: center;
-    margin-left: 34px;
+    margin-left: auto;
-    width: 50%;
+    margin-right: auto;
+    width: 100%;
   }
 
   .main-head {
-    font-size: 5rem;
+    font-size: 4rem;
     color: #6dd6f4;
-    margin: 6px 0px 24px 22px;
     font-family: "Sulphur Point", sans-serif;
-    font-weight: 500;
+    display: flex;
-    letter-spacing: 4px;
+    justify-content: center;
+    align-items: center;
+    margin-left: auto;
+    margin-right: auto;
+    font-weight: 400;
+    letter-spacing: 2px;
     text-decoration: underline;
   }
 
   .material-symbols-outlined {
-    margin: 13px 74px 0px 0px;
+    display: none !important;
-    font-size: 82px;
+  }
-    color: #6dd6f4;
+}
-    font-variation-settings:
-    'FILL' 0,
-    'wght' 300,
-    'GRAD' 0,
-    'opsz' 24
-  }

frontend/src/styles/stickies.css

@@ -3,6 +3,7 @@
   flex-wrap: wrap;
   gap: 16px;
   justify-content: center;
+  margin-top: 18px;
   padding: 24px;
 }
 
@@ -23,8 +24,69 @@
   padding: 16px;
 }
 
+.cluster-draggable {
+  cursor: grab;
+  transition: box-shadow 0.2s ease, border-color 0.2s ease, transform 0.15s ease;
+}
+
+.cluster-draggable:active {
+  cursor: grabbing;
+}
+
+.cluster-drag-over {
+  border-color: #ffb7ce;
+  box-shadow: 0 0 12px rgba(255, 183, 206, 0.4);
+  transform: scale(1.01);
+}
+
+.cluster-header {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  margin-bottom: 16px;
+}
+
+.cluster-rank {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 32px;
+  height: 32px;
+  border-radius: 50%;
+  background: #6dd6f4;
+  color: #1a1a2e;
+  font-weight: 700;
+  font-size: 0.95em;
+  flex-shrink: 0;
+}
+
 .cluster-label {
-  margin: 0 0 16px 0;
+  margin: 0;
   font-size: 1.2em;
   font-weight: 600;
+  flex: 1;
+}
+
+.cluster-drag-handle {
+  font-size: 1.4em;
+  color: #6dd6f4;
+  opacity: 0.4;
+  user-select: none;
+  transition: opacity 0.2s ease;
+  flex-shrink: 0;
+}
+
+.cluster-draggable:hover .cluster-drag-handle {
+  opacity: 0.8;
+}
+
+.cohesion-score {
+  text-align: center;
+  font-size: 0.95em;
+  color: #e0e0e0;
+  padding: 8px 16px;
+  background: rgba(109, 214, 244, 0.1);
+  border-radius: 6px;
+  width: fit-content;
+  margin: 0 auto;
 }

frontend/src/tests/stickies.test.tsx

@@ -9,10 +9,13 @@ const MOCK_STICKIES = [
   { id: 'note_002', text: 'Export takes too long', x: 798, y: 211, author: 'user_2', color: 'green' },
 ];
 
-const MOCK_CLUSTERS = [
+const MOCK_CLUSTER_RESPONSE = {
-  { label: 'Auth Issues', noteIds: ['note_001'] },
+  clusters: [
-  { label: 'Export Issues', noteIds: ['note_002'] },
+    { label: 'Auth Issues', noteIds: ['note_001'] },
-];
+    { label: 'Export Issues', noteIds: ['note_002'] },
+  ],
+  score: 0.74,
+};
 
 let fetchMock: ReturnType<typeof vi.fn>;
 
@@ -70,10 +73,9 @@ describe('Stickies', () => {
   });
 
   it('should show cluster labels after clustering succeeds', async () => {
-    // First call = GET notes, second call = POST cluster
     fetchMock
       .mockReturnValueOnce(mockFetchOk(MOCK_STICKIES))
-      .mockReturnValueOnce(mockFetchOk(MOCK_CLUSTERS));
+      .mockReturnValueOnce(mockFetchOk(MOCK_CLUSTER_RESPONSE));
 
     const { Wrapper } = createTestWrapper();
     render(<Stickies />, { wrapper: Wrapper });
@@ -90,7 +92,7 @@ describe('Stickies', () => {
   it('should still render sticky note text inside clusters', async () => {
     fetchMock
       .mockReturnValueOnce(mockFetchOk(MOCK_STICKIES))
-      .mockReturnValueOnce(mockFetchOk(MOCK_CLUSTERS));
+      .mockReturnValueOnce(mockFetchOk(MOCK_CLUSTER_RESPONSE));
 
     const { Wrapper } = createTestWrapper();
     render(<Stickies />, { wrapper: Wrapper });
@@ -101,4 +103,41 @@ describe('Stickies', () => {
     expect(await screen.findByText('Login flow feels confusing')).toBeInTheDocument();
     expect(screen.getByText('Export takes too long')).toBeInTheDocument();
   });
+
+  it('should display rank badges on clustered groups', async () => {
+    fetchMock
+      .mockReturnValueOnce(mockFetchOk(MOCK_STICKIES))
+      .mockReturnValueOnce(mockFetchOk(MOCK_CLUSTER_RESPONSE));
+
+    const { Wrapper } = createTestWrapper();
+    render(<Stickies />, { wrapper: Wrapper });
+
+    const btn = await screen.findByRole('button', { name: 'Group Stickies By Topic' });
+    await userEvent.click(btn);
+
+    await waitFor(() => {
+      expect(screen.getByLabelText('Priority 1')).toBeInTheDocument();
+      expect(screen.getByLabelText('Priority 2')).toBeInTheDocument();
+    });
+  });
+
+  it('should make cluster groups draggable', async () => {
+    fetchMock
+      .mockReturnValueOnce(mockFetchOk(MOCK_STICKIES))
+      .mockReturnValueOnce(mockFetchOk(MOCK_CLUSTER_RESPONSE));
+
+    const { Wrapper } = createTestWrapper();
+    render(<Stickies />, { wrapper: Wrapper });
+
+    const btn = await screen.findByRole('button', { name: 'Group Stickies By Topic' });
+    await userEvent.click(btn);
+
+    await waitFor(() => {
+      const groups = document.querySelectorAll('.cluster-draggable');
+      groups.forEach((group) => {
+        expect(group).toHaveAttribute('draggable', 'true');
+      });
+      expect(groups.length).toBe(2);
+    });
+  });
 });

frontend/src/types/types.d.ts

@@ -11,3 +11,12 @@ export type Cluster = {
   label: string;
   noteIds: string[];
 };
+
+export type ClusterResponse = {
+  clusters: Cluster[];
+  score: number;
+};
+
+export type RankedCluster = Cluster & {
+  rank: number;
+};