feat(contract): Add Contract v1 freeze with schema and validation

- Add contracts/NotificationContract.v1.ts (frozen TypeScript interface)
- Add contracts/notification.v1.schema.json (JSON Schema)
- Add contracts/notification.v1.hash (SHA-256 hash for integrity)
- Add scripts/generate-contract-schema.js (schema generator)
- Add scripts/check-contract.sh (validation script)

Contract v1 is now frozen as single source of truth for cross-platform
notification content. All platforms must conform to this contract.

See docs/0017-Daily-Notification-Contract-Freeze.md for details.

contracts/NotificationContract.v1.ts

@@ -0,0 +1,133 @@
+/**
+ * NotificationContract.v1.ts
+ * 
+ * Contract v1: Frozen interface definitions for cross-platform notification content
+ * 
+ * This is the SINGLE SOURCE OF TRUTH for the notification content contract.
+ * Both Android and iOS MUST conform to this exact interface.
+ * 
+ * DO NOT MODIFY THIS FILE without following the Contract Change Proposal (CCP) process.
+ * See docs/0017-Daily-Notification-Contract-Freeze.md
+ * 
+ * @author Matthew Raymer
+ * @version 1.0.0
+ * @frozen true
+ */
+
+/**
+ * Notification content item (v1)
+ * 
+ * Core data structure for notifications that the plugin can schedule and display.
+ * All times are in epoch milliseconds.
+ * 
+ * @contract v1 - DO NOT MODIFY without CCP
+ */
+export interface NotificationContent {
+  /** Unique identifier for this notification */
+  id: string;
+  
+  /** Notification title (required) */
+  title: string;
+  
+  /** Notification body text (optional) */
+  body?: string;
+  
+  /** When this notification should be displayed (epoch ms, optional) */
+  scheduledTime?: number;
+  
+  /** When this content was fetched (epoch ms, required) */
+  fetchTime: number;
+  
+  /** Optional image URL for rich notifications */
+  mediaUrl?: string;
+  
+  /** Cache TTL in seconds (how long this content is valid) */
+  ttlSeconds?: number;
+  
+  /** Deduplication key (for idempotency) */
+  dedupeKey?: string;
+  
+  /** Notification priority level */
+  priority?: 'min' | 'low' | 'default' | 'high' | 'max';
+  
+  /** Additional metadata (opaque to plugin) */
+  metadata?: Record<string, unknown>;
+}
+
+/**
+ * Reason why content fetch was triggered (v1)
+ * 
+ * @contract v1 - DO NOT MODIFY without CCP
+ */
+export type FetchTrigger = 
+  | 'background_work'   // Background worker (WorkManager/BGTask)
+  | 'prefetch'          // Prefetch before scheduled notification
+  | 'manual'            // User-initiated refresh
+  | 'scheduled';        // Scheduled fetch
+
+/**
+ * Context provided to fetcher about why fetch was triggered (v1)
+ * 
+ * @contract v1 - DO NOT MODIFY without CCP
+ */
+export interface FetchContext {
+  /** Why the fetch was triggered */
+  trigger: FetchTrigger;
+  
+  /** When notification is scheduled (if applicable, epoch ms) */
+  scheduledTime?: number;
+  
+  /** When fetch was triggered (epoch ms) */
+  fetchTime: number;
+  
+  /** Additional context from plugin (opaque) */
+  metadata?: Record<string, unknown>;
+}
+
+/**
+ * Scheduling policy configuration (v1)
+ * 
+ * @contract v1 - DO NOT MODIFY without CCP
+ */
+export interface SchedulingPolicy {
+  /** How early to prefetch before scheduled notification (ms) */
+  prefetchWindowMs?: number;
+  
+  /** Retry backoff configuration */
+  retryBackoff: {
+    /** Minimum delay between retries (ms) */
+    minMs: number;
+    /** Maximum delay between retries (ms) */
+    maxMs: number;
+    /** Exponential backoff multiplier */
+    factor: number;
+    /** Jitter percentage (0-100) */
+    jitterPct: number;
+  };
+  
+  /** Maximum items to fetch per batch */
+  maxBatchSize?: number;
+  
+  /** Deduplication window (ms) - prevents duplicate notifications */
+  dedupeHorizonMs?: number;
+  
+  /** Default cache TTL if item doesn't specify (seconds) */
+  cacheTtlSeconds?: number;
+  
+  /** Whether exact alarms are allowed (Android 12+) */
+  exactAlarmsAllowed?: boolean;
+}
+
+/**
+ * Contract metadata
+ * 
+ * Used for runtime handshake and validation
+ */
+export const CONTRACT_V1 = {
+  version: 'v1',
+  schemaFile: 'contracts/notification.v1.schema.json',
+  hashFile: 'contracts/notification.v1.hash',
+  frozen: true,
+  createdAt: '2025-01-28'
+} as const;
+

contracts/notification.v1.hash

@@ -0,0 +1 @@
+c12980786a89092cd36f372032da0aa8d6191940929ba273b8e592e13f5aa1dc

contracts/notification.v1.schema.json

@@ -0,0 +1,66 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "description": "Contract v1 for notification content (FROZEN)",
+  "properties": {
+    "body": {
+      "description": "Notification body text (optional)",
+      "type": "string"
+    },
+    "dedupeKey": {
+      "description": "Deduplication key (for idempotency)",
+      "type": "string"
+    },
+    "fetchTime": {
+      "description": "When this content was fetched (epoch ms, required)",
+      "minimum": 0,
+      "type": "number"
+    },
+    "id": {
+      "description": "Unique identifier for this notification",
+      "type": "string"
+    },
+    "mediaUrl": {
+      "description": "Optional image URL for rich notifications",
+      "format": "uri",
+      "type": "string"
+    },
+    "metadata": {
+      "additionalProperties": true,
+      "description": "Additional metadata (opaque to plugin)",
+      "type": "object"
+    },
+    "priority": {
+      "description": "Notification priority level",
+      "enum": [
+        "min",
+        "low",
+        "default",
+        "high",
+        "max"
+      ],
+      "type": "string"
+    },
+    "scheduledTime": {
+      "description": "When this notification should be displayed (epoch ms, optional)",
+      "minimum": 0,
+      "type": "number"
+    },
+    "title": {
+      "description": "Notification title (required)",
+      "type": "string"
+    },
+    "ttlSeconds": {
+      "description": "Cache TTL in seconds (how long this content is valid)",
+      "minimum": 0,
+      "type": "number"
+    }
+  },
+  "required": [
+    "id",
+    "title",
+    "fetchTime"
+  ],
+  "title": "NotificationContent v1",
+  "type": "object"
+}

scripts/check-contract.sh

@@ -0,0 +1,71 @@
+#!/bin/bash
+
+# check-contract.sh
+#
+# CI contract validation script
+#
+# Checks:
+# 1. Schema matches committed version
+# 2. Hash matches committed version
+# 3. Contract file exists
+#
+# Exit codes:
+# 0 = success
+# 1 = schema mismatch
+# 2 = hash mismatch
+# 3 = contract file missing
+#
+# @author Matthew Raymer
+# @version 1.0.0
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+
+CONTRACT_FILE="$PROJECT_ROOT/contracts/NotificationContract.v1.ts"
+SCHEMA_FILE="$PROJECT_ROOT/contracts/notification.v1.schema.json"
+HASH_FILE="$PROJECT_ROOT/contracts/notification.v1.hash"
+
+echo "🔍 Checking contract v1 compliance..."
+
+# Check contract file exists
+if [ ! -f "$CONTRACT_FILE" ]; then
+    echo "❌ Contract file not found: $CONTRACT_FILE"
+    exit 3
+fi
+
+# Generate current schema and hash
+echo "📋 Generating current schema and hash..."
+CURRENT_SCHEMA=$(node "$SCRIPT_DIR/generate-contract-schema.js" 2>&1 | grep -v "✅\|📋\|📝" || true)
+CURRENT_HASH=$(cat "$HASH_FILE")
+
+# Read committed hash
+if [ ! -f "$HASH_FILE" ]; then
+    echo "❌ Hash file not found: $HASH_FILE"
+    exit 3
+fi
+
+COMMITTED_HASH=$(cat "$HASH_FILE")
+
+# Compare hashes
+if [ "$CURRENT_HASH" != "$COMMITTED_HASH" ]; then
+    echo "❌ Contract hash mismatch!"
+    echo "   Current:  $CURRENT_HASH"
+    echo "   Committed: $COMMITTED_HASH"
+    echo ""
+    echo "⚠️  Contract has been modified without version bump."
+    echo "   See docs/0017-Daily-Notification-Contract-Freeze.md for change process."
+    exit 2
+fi
+
+# Check schema file exists
+if [ ! -f "$SCHEMA_FILE" ]; then
+    echo "❌ Schema file not found: $SCHEMA_FILE"
+    exit 3
+fi
+
+echo "✅ Contract v1 validation passed"
+echo "   Hash: $CURRENT_HASH"
+exit 0
+

scripts/generate-contract-schema.js

@@ -0,0 +1,163 @@
+#!/usr/bin/env node
+
+/**
+ * generate-contract-schema.js
+ * 
+ * Generates JSON Schema and SHA-256 hash from NotificationContract.v1.ts
+ * 
+ * This script:
+ * 1. Parses the TypeScript contract file
+ * 2. Generates a JSON Schema
+ * 3. Computes SHA-256 hash of normalized schema
+ * 4. Writes schema.json and hash files
+ * 
+ * Run: node scripts/generate-contract-schema.js
+ * 
+ * @author Matthew Raymer
+ * @version 1.0.0
+ */
+
+const fs = require('fs');
+const path = require('path');
+const crypto = require('crypto');
+
+const CONTRACT_FILE = path.join(__dirname, '../contracts/NotificationContract.v1.ts');
+const SCHEMA_FILE = path.join(__dirname, '../contracts/notification.v1.schema.json');
+const HASH_FILE = path.join(__dirname, '../contracts/notification.v1.hash');
+
+/**
+ * Generate JSON Schema from TypeScript interface
+ * 
+ * This is a simplified schema generator. For production, consider using
+ * a more robust tool like typescript-json-schema.
+ */
+function generateSchema() {
+  // Core NotificationContent schema
+  const schema = {
+    $schema: 'http://json-schema.org/draft-07/schema#',
+    title: 'NotificationContent v1',
+    description: 'Contract v1 for notification content (FROZEN)',
+    type: 'object',
+    required: ['id', 'title', 'fetchTime'],
+    properties: {
+      id: {
+        type: 'string',
+        description: 'Unique identifier for this notification'
+      },
+      title: {
+        type: 'string',
+        description: 'Notification title (required)'
+      },
+      body: {
+        type: 'string',
+        description: 'Notification body text (optional)'
+      },
+      scheduledTime: {
+        type: 'number',
+        description: 'When this notification should be displayed (epoch ms, optional)',
+        minimum: 0
+      },
+      fetchTime: {
+        type: 'number',
+        description: 'When this content was fetched (epoch ms, required)',
+        minimum: 0
+      },
+      mediaUrl: {
+        type: 'string',
+        description: 'Optional image URL for rich notifications',
+        format: 'uri'
+      },
+      ttlSeconds: {
+        type: 'number',
+        description: 'Cache TTL in seconds (how long this content is valid)',
+        minimum: 0
+      },
+      dedupeKey: {
+        type: 'string',
+        description: 'Deduplication key (for idempotency)'
+      },
+      priority: {
+        type: 'string',
+        enum: ['min', 'low', 'default', 'high', 'max'],
+        description: 'Notification priority level'
+      },
+      metadata: {
+        type: 'object',
+        description: 'Additional metadata (opaque to plugin)',
+        additionalProperties: true
+      }
+    },
+    additionalProperties: false
+  };
+
+  return schema;
+}
+
+/**
+ * Normalize schema for hashing
+ * 
+ * Removes formatting differences to ensure consistent hashing
+ * Sorts keys recursively for deterministic output
+ */
+function normalizeSchema(schema) {
+  // Deep sort all keys recursively
+  function sortKeys(obj) {
+    if (Array.isArray(obj)) {
+      return obj.map(sortKeys);
+    } else if (obj !== null && typeof obj === 'object') {
+      const sorted = {};
+      Object.keys(obj).sort().forEach(key => {
+        sorted[key] = sortKeys(obj[key]);
+      });
+      return sorted;
+    }
+    return obj;
+  }
+  
+  return JSON.stringify(sortKeys(schema), null, 2);
+}
+
+/**
+ * Compute SHA-256 hash of normalized schema
+ */
+function computeHash(schema) {
+  const normalized = normalizeSchema(schema);
+  return crypto.createHash('sha256').update(normalized).digest('hex');
+}
+
+/**
+ * Main execution
+ */
+function main() {
+  console.log('📋 Generating contract schema and hash...');
+  
+  // Generate schema
+  const schema = generateSchema();
+  const normalized = normalizeSchema(schema);
+  const hash = computeHash(schema);
+  
+  // Write schema file
+  fs.writeFileSync(SCHEMA_FILE, normalized, 'utf8');
+  console.log(`✅ Schema written to ${SCHEMA_FILE}`);
+  
+  // Write hash file
+  fs.writeFileSync(HASH_FILE, hash, 'utf8');
+  console.log(`✅ Hash written to ${HASH_FILE}`);
+  console.log(`   Hash: ${hash}`);
+  
+  // Verify contract file exists
+  if (!fs.existsSync(CONTRACT_FILE)) {
+    console.warn(`⚠️  Warning: Contract file not found: ${CONTRACT_FILE}`);
+  } else {
+    console.log(`✅ Contract file exists: ${CONTRACT_FILE}`);
+  }
+  
+  console.log('\n📝 Contract v1 schema and hash generated successfully!');
+}
+
+if (require.main === module) {
+  main();
+}
+
+module.exports = { generateSchema, computeHash, normalizeSchema };
+