diff --git a/.eslintrc.json b/.eslintrc.json
new file mode 100644
index 0000000..e8a2566
--- /dev/null
+++ b/.eslintrc.json
@@ -0,0 +1,33 @@
+{
+  "root": true,
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": 2020,
+    "sourceType": "module",
+    "project": "./tsconfig.json"
+  },
+  "plugins": ["@typescript-eslint"],
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+    "plugin:@typescript-eslint/recommended-requiring-type-checking"
+  ],
+  "rules": {
+    "@typescript-eslint/no-unused-vars": [
+      "error",
+      { "argsIgnorePattern": "^_" }
+    ],
+    "@typescript-eslint/explicit-function-return-type": [
+      "warn",
+      { "allowExpressions": true }
+    ],
+    "@typescript-eslint/no-explicit-any": "error",
+    "@typescript-eslint/no-non-null-assertion": "warn",
+    "no-console": ["warn", { "allow": ["warn", "error"] }]
+  },
+  "env": {
+    "node": true,
+    "es6": true
+  },
+  "ignorePatterns": ["dist", "node_modules", "*.js"]
+}
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..7e71adf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,40 @@
+# Dependencies
+node_modules/
+package-lock.json
+yarn.lock
+
+# Build outputs
+dist/
+*.tsbuildinfo
+
+# Test coverage
+coverage/
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Environment
+.env
+.env.local
+.env.*.local
+
+# Temporary files
+*.tmp
+.cache/
+
+# Backup files
+*.backup
diff --git a/.prettierignore b/.prettierignore
new file mode 100644
index 0000000..7717b0c
--- /dev/null
+++ b/.prettierignore
@@ -0,0 +1,5 @@
+node_modules
+dist
+coverage
+*.log
+.git
diff --git a/.prettierrc.json b/.prettierrc.json
new file mode 100644
index 0000000..32a2397
--- /dev/null
+++ b/.prettierrc.json
@@ -0,0 +1,10 @@
+{
+  "semi": true,
+  "trailingComma": "es5",
+  "singleQuote": true,
+  "printWidth": 100,
+  "tabWidth": 2,
+  "useTabs": false,
+  "arrowParens": "always",
+  "endOfLine": "lf"
+}
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..c9a7e90
--- /dev/null
+++ b/README.md
@@ -0,0 +1,77 @@
+# ByteGrid
+
+> Binary data and C struct memory layout visualization for Obsidian
+
+## Overview
+
+**ByteGrid** is an Obsidian plugin that visualizes binary data and C structure memory layouts as interactive SVG diagrams.
+
+## Features
+
+- 🎨 Color-coded field visualization
+- 📏 Byte-accurate grid layout
+- 🔍 Bitfield support
+- 📊 Hex dump integration
+- 🎯 Interactive tooltips
+- 📤 Multiple export formats (SVG, PNG, C code, Markdown)
+
+## Project Status
+
+🚧 **In Development** - Currently in Phase 1 (MVP)
+
+## Quick Start
+
+```bash
+# Install dependencies
+npm install
+
+# Build all packages
+npm run build
+
+# Run tests
+npm run test
+
+# Lint
+npm run lint
+
+# Format code
+npm run format
+```
+
+## Project Structure
+
+```
+bytegrid/
+├── packages/
+│   ├── core/              # Core rendering logic
+│   └── obsidian-plugin/   # Obsidian plugin
+├── docs/                  # Design documentation
+└── examples/              # Example files
+```
+
+## Documentation
+
+See [CLAUDE.md](./CLAUDE.md) for detailed project guidelines and architecture.
+
+## Development
+
+This project follows **Test-Driven Development (TDD)**:
+
+1. Write tests first
+2. Implement minimal code to pass tests
+3. Refactor
+
+### Key Principles
+
+- **offset is SSOT** - Field size calculated from offset ranges
+- **No magic numbers** - Use constants for all layout values
+- **Dynamic height** - SVG dimensions calculated from content
+- **Explicit padding** - Use `reserved` or `padding` types
+
+## License
+
+MIT License - see [LICENSE](./LICENSE) for details
+
+## Contributing
+
+Currently in initial development phase. Contribution guidelines will be added soon.
diff --git a/jest.config.js b/jest.config.js
new file mode 100644
index 0000000..428264c
--- /dev/null
+++ b/jest.config.js
@@ -0,0 +1,22 @@
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  roots: ['<rootDir>/packages'],
+  testMatch: ['**/__tests__/**/*.ts', '**/?(*.)+(spec|test).ts'],
+  collectCoverageFrom: [
+    'packages/*/src/**/*.ts',
+    '!packages/*/src/**/*.d.ts',
+    '!packages/*/src/index.ts',
+  ],
+  coverageThreshold: {
+    global: {
+      branches: 80,
+      functions: 80,
+      lines: 80,
+      statements: 80,
+    },
+  },
+  moduleNameMapper: {
+    '^@bytegrid/core$': '<rootDir>/packages/core/src',
+  },
+};
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..f0475f7
--- /dev/null
+++ b/package.json
@@ -0,0 +1,42 @@
+{
+  "name": "bytegrid",
+  "version": "0.1.0",
+  "description": "Binary data and C struct memory layout visualization for Obsidian",
+  "private": true,
+  "workspaces": [
+    "packages/*"
+  ],
+  "scripts": {
+    "build": "npm run build --workspaces",
+    "test": "npm run test --workspaces",
+    "lint": "eslint . --ext .ts",
+    "format": "prettier --write \"**/*.{ts,json,md}\"",
+    "format:check": "prettier --check \"**/*.{ts,json,md}\"",
+    "clean": "rm -rf packages/*/dist packages/*/node_modules node_modules"
+  },
+  "keywords": [
+    "obsidian",
+    "obsidian-plugin",
+    "binary",
+    "visualization",
+    "memory-layout",
+    "struct"
+  ],
+  "author": "ByteGrid Contributors",
+  "license": "MIT",
+  "devDependencies": {
+    "@types/jest": "^29.5.11",
+    "@types/node": "^20.10.6",
+    "@typescript-eslint/eslint-plugin": "^6.17.0",
+    "@typescript-eslint/parser": "^6.17.0",
+    "eslint": "^8.56.0",
+    "jest": "^29.7.0",
+    "prettier": "^3.1.1",
+    "ts-jest": "^29.1.1",
+    "typescript": "^5.3.3"
+  },
+  "engines": {
+    "node": ">=18.0.0",
+    "npm": ">=9.0.0"
+  }
+}
diff --git a/packages/core/jest.config.js b/packages/core/jest.config.js
new file mode 100644
index 0000000..e5330c3
--- /dev/null
+++ b/packages/core/jest.config.js
@@ -0,0 +1,7 @@
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  roots: ['<rootDir>/tests'],
+  testMatch: ['**/?(*.)+(spec|test).ts'],
+  collectCoverageFrom: ['src/**/*.ts', '!src/**/*.d.ts', '!src/index.ts'],
+};
diff --git a/packages/core/package.json b/packages/core/package.json
new file mode 100644
index 0000000..c22cc38
--- /dev/null
+++ b/packages/core/package.json
@@ -0,0 +1,26 @@
+{
+  "name": "@bytegrid/core",
+  "version": "0.1.0",
+  "description": "Core rendering logic for ByteGrid",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "scripts": {
+    "build": "tsc",
+    "test": "jest",
+    "test:watch": "jest --watch",
+    "test:coverage": "jest --coverage"
+  },
+  "keywords": [
+    "bytegrid",
+    "binary",
+    "visualization"
+  ],
+  "author": "ByteGrid Contributors",
+  "license": "MIT",
+  "dependencies": {
+    "js-yaml": "^4.1.0"
+  },
+  "devDependencies": {
+    "@types/js-yaml": "^4.0.9"
+  }
+}
diff --git a/packages/core/src/errors.ts b/packages/core/src/errors.ts
new file mode 100644
index 0000000..04b1ac5
--- /dev/null
+++ b/packages/core/src/errors.ts
@@ -0,0 +1,58 @@
+/**
+ * Custom error classes for ByteGrid
+ */
+
+/**
+ * Base error class for ByteGrid
+ */
+export class ByteGridError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = 'ByteGridError';
+    Object.setPrototypeOf(this, ByteGridError.prototype);
+  }
+}
+
+/**
+ * Error thrown during YAML parsing
+ */
+export class ParseError extends ByteGridError {
+  constructor(message: string, public readonly fieldIndex?: number) {
+    super(message);
+    this.name = 'ParseError';
+    Object.setPrototypeOf(this, ParseError.prototype);
+  }
+}
+
+/**
+ * Error thrown during validation
+ */
+export class ValidationError extends ByteGridError {
+  constructor(message: string, public readonly fieldIndex?: number) {
+    super(message);
+    this.name = 'ValidationError';
+    Object.setPrototypeOf(this, ValidationError.prototype);
+  }
+}
+
+/**
+ * Error thrown during rendering
+ */
+export class RenderError extends ByteGridError {
+  constructor(message: string) {
+    super(message);
+    this.name = 'RenderError';
+    Object.setPrototypeOf(this, RenderError.prototype);
+  }
+}
+
+/**
+ * Error thrown during binary parsing
+ */
+export class BinaryParseError extends ByteGridError {
+  constructor(message: string, public readonly offset?: number) {
+    super(message);
+    this.name = 'BinaryParseError';
+    Object.setPrototypeOf(this, BinaryParseError.prototype);
+  }
+}
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
new file mode 100644
index 0000000..6672a89
--- /dev/null
+++ b/packages/core/src/index.ts
@@ -0,0 +1,12 @@
+/**
+ * ByteGrid Core - Public API
+ */
+
+export * from './types';
+export * from './errors';
+
+// TODO: Export parser, validator, layoutEngine, svgRenderer when implemented
+// export { parse } from './parser';
+// export { validate } from './validator';
+// export { createLayout } from './layoutEngine';
+// export { renderSVG } from './svgRenderer';
diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
new file mode 100644
index 0000000..9935393
--- /dev/null
+++ b/packages/core/src/types.ts
@@ -0,0 +1,123 @@
+/**
+ * Core type definitions for ByteGrid
+ */
+
+/**
+ * Supported data types in ByteGrid
+ */
+export type DataType =
+  | 'char'
+  | 'int8_t'
+  | 'uint8_t'
+  | 'int16_t'
+  | 'uint16_t'
+  | 'short'
+  | 'int32_t'
+  | 'uint32_t'
+  | 'int'
+  | 'int64_t'
+  | 'uint64_t'
+  | 'long'
+  | 'float'
+  | 'double'
+  | 'reserved'
+  | 'padding'
+  | string; // For array types like 'char[4]'
+
+/**
+ * Endianness for multi-byte fields
+ */
+export type Endianness = 'little' | 'big';
+
+/**
+ * Color names for field visualization
+ */
+export type ColorName =
+  | 'blue'
+  | 'cyan'
+  | 'yellow'
+  | 'green'
+  | 'orange'
+  | 'purple'
+  | 'mint'
+  | 'pink'
+  | 'gray';
+
+/**
+ * Color scheme variants
+ */
+export type ColorScheme = 'default' | 'dark' | 'light';
+
+/**
+ * Bitfield definition within a field
+ */
+export interface Bitfield {
+  name: string;
+  bits: string; // e.g., "0-3" or "7"
+  description?: string;
+}
+
+/**
+ * Field definition
+ * Note: size is calculated from offset (SSOT principle)
+ */
+export interface Field {
+  offset: string; // e.g., "0-3" or "4" (SSOT for size calculation)
+  name: string;
+  type: DataType;
+  value?: string;
+  description?: string;
+  color?: ColorName;
+  endianness?: Endianness;
+  bitfields?: Bitfield[];
+}
+
+/**
+ * Main configuration for ByteGrid visualization
+ */
+export interface ByteGridConfig {
+  name: string;
+  size: number; // Total size in bytes
+  layout?: number; // Bytes per row (default: 16)
+  colorScheme?: ColorScheme;
+  fields: Field[];
+}
+
+/**
+ * Parsed offset information
+ */
+export interface OffsetRange {
+  start: number;
+  end: number;
+  size: number;
+}
+
+/**
+ * Layout block for rendering (after layout engine processing)
+ */
+export interface LayoutBlock {
+  row: number;
+  col: number;
+  span: number; // Number of columns this block spans
+  fieldName: string;
+  fieldType: DataType;
+  color: ColorName;
+  value?: string;
+  description?: string;
+  offsetStart: number;
+  offsetEnd: number;
+  isPadding: boolean;
+  bitfields?: Bitfield[];
+}
+
+/**
+ * Rendering options
+ */
+export interface RenderOptions {
+  showHexDump?: boolean;
+  showLegend?: boolean;
+  showGrid?: boolean;
+  cellWidth?: number;
+  cellHeight?: number;
+  fontSize?: number;
+}
diff --git a/packages/core/tsconfig.json b/packages/core/tsconfig.json
new file mode 100644
index 0000000..2a28f2b
--- /dev/null
+++ b/packages/core/tsconfig.json
@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./dist",
+    "rootDir": "./src"
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist", "tests"]
+}
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..b5673d2
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,24 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "commonjs",
+    "lib": ["ES2020"],
+    "declaration": true,
+    "declarationMap": true,
+    "sourceMap": true,
+    "outDir": "./dist",
+    "rootDir": "./",
+    "composite": true,
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "moduleResolution": "node",
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true
+  },
+  "exclude": ["node_modules", "dist", "**/*.test.ts"]
+}