added README and usage.

README.md

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+# TS-Roots - Nostr Protocol Library for TypeScript
+
+Source: https://git.wisehodl.dev/jay/ts-roots
+
+Mirror: https://github.com/wisehodl/ts-roots
+
+## What this library does
+
+`ts-roots` is a purposefully minimal Nostr protocol library for TypeScript.
+It only provides primitives that define protocol compliance:
+
+- Event Structure
+- Serialization
+- Cryptographic Signatures
+- Subscription Filters
+
+## What this library does not do
+
+`ts-roots` serves as a foundation for other libraries and applications to
+implement higher level abstractions of the Nostr protocol on top of it,
+including message transport, semantic event definitions, event storage
+mechanisms, and user interfaces.
+
+`ts-roots` prioritizes correctness and clarity over optimization and efficiency. For high performance applications, it is recommended to implement optimizations in a separate library or in the application which requires them.
+
+## Installation
+
+1. Add `ts-roots` to your project:
+
+```bash
+npm install @wisehodl/roots
+```
+
+2. Import it:
+
+```typescript
+import { Event, Filter, Keys } from '@wisehodl/roots';
+import type { EventData, FilterData } from '@wisehodl/roots';
+```
+
+## Usage Examples
+
+### Key Management
+
+#### Generate a new keypair
+
+```typescript
+const privateKey = Keys.generatePrivateKey();
+const publicKey = Keys.getPublicKey(privateKey);
+```
+
+#### Derive public key from existing private key
+
+```typescript
+const privateKey = "f43a0435f69529f310bbd1d6263d2fbf0977f54bfe2310cc37ae5904b83bb167";
+const publicKey = Keys.getPublicKey(privateKey);
+// publicKey: "cfa87f35acbde29ba1ab3ee42de527b2cad33ac487e80cf2d6405ea0042c8fef"
+```
+
+---
+
+### Event Creation and Signing
+
+#### Create and sign a complete event
+
+```typescript
+// 1. Build the event structure
+const event: EventData = {
+  pubkey: publicKey,
+  created_at: Math.floor(Date.now() / 1000),
+  kind: 1,
+  tags: [
+    ["e", "5c83da77af1dec6d7289834998ad7aafbd9e2191396d75ec3cc27f5a77226f36"],
+    ["p", "91cf9b32f3735070f46c0a86a820a47efa08a5be6c9f4f8cf68e5b5b75c92d60"],
+  ],
+  content: "Hello, Nostr!",
+  id: "",
+  sig: "",
+};
+
+// 2. Compute the event ID
+const id = Event.getID(event);
+event.id = id;
+
+// 3. Sign the event
+const sig = Event.sign(id, privateKey);
+event.sig = sig;
+```
+
+#### Serialize an event for ID computation
+
+```typescript
+// Returns canonical JSON: [0, pubkey, created_at, kind, tags, content]
+const serialized = Event.serialize(event);
+```
+
+#### Compute event ID manually
+
+```typescript
+const id = Event.getID(event);
+// Returns lowercase hex SHA-256 hash of serialized form
+```
+
+---
+
+### Event Validation
+
+#### Validate complete event
+
+```typescript
+// Checks structure, ID computation, and signature
+try {
+  Event.validate(event);
+} catch (err) {
+  console.log(`Invalid event: ${err.message}`);
+}
+```
+
+#### Validate individual aspects
+
+```typescript
+// Check field formats and lengths
+try {
+  Event.validateStructure(event);
+} catch (err) {
+  console.log(`Malformed structure: ${err.message}`);
+}
+
+// Verify ID matches computed hash
+try {
+  Event.validateID(event);
+} catch (err) {
+  console.log(`ID mismatch: ${err.message}`);
+}
+
+// Verify cryptographic signature
+try {
+  Event.validateSignature(event);
+} catch (err) {
+  console.log(`Invalid signature: ${err.message}`);
+}
+```
+
+---
+
+### Event JSON
+
+#### Marshal event to JSON
+
+```typescript
+const jsonString = JSON.stringify(Event.toJSON(event));
+// Standard JSON.stringify works with Event.toJSON()
+```
+
+#### Unmarshal event from JSON
+
+```typescript
+const event = Event.fromJSON(JSON.parse(jsonString));
+
+// Validate after unmarshaling
+try {
+  Event.validate(event);
+} catch (err) {
+  console.log(`Received invalid event: ${err.message}`);
+}
+```
+
+---
+
+### Filter Creation
+
+#### Basic filter with standard fields
+
+```typescript
+const since = Math.floor(Date.now() / 1000) - (24 * 60 * 60);
+const limit = 50;
+
+const filter: FilterData = {
+  ids: ["abc123", "def456"],  // Prefix match
+  authors: ["cfa87f35"],      // Prefix match
+  kinds: [1, 6, 7],
+  since: since,
+  limit: limit,
+};
+```
+
+#### Filter with tag conditions
+
+```typescript
+const filter: FilterData = {
+  kinds: [1],
+  tags: {
+    e: ["5c83da77af1dec6d7289834998ad7aafbd9e2191396d75ec3cc27f5a77226f36"],
+    p: ["91cf9b32f3735070f46c0a86a820a47efa08a5be6c9f4f8cf68e5b5b75c92d60"],
+  },
+};
+```
+
+#### Filter with extensions (custom fields)
+
+```typescript
+// Extensions allow arbitrary JSON fields beyond the standard filter spec.
+// For example, this is how to implement non-standard filters like 'search'.
+const filter: FilterData = {
+  kinds: [1],
+  extensions: {
+    search: "bitcoin",
+  },
+};
+
+// Extensions are preserved during marshal/unmarshal but ignored by matches().
+// Storage/transport layers can inspect extensions to implement custom behavior.
+```
+
+---
+
+### Filter Matching
+
+#### Match single event
+
+```typescript
+const filter: FilterData = {
+  authors: ["cfa87f35"],
+  kinds: [1],
+};
+
+if (Filter.matches(filter, event)) {
+  // Event satisfies all filter conditions
+}
+```
+
+#### Filter event collection
+
+```typescript
+const since = Math.floor(Date.now() / 1000) - (60 * 60);
+const filter: FilterData = {
+  kinds: [1],
+  since: since,
+  tags: {
+    p: ["abc123", "def456"],  // OR within tag values
+  },
+};
+
+const matches = events.filter(event => Filter.matches(filter, event));
+```
+
+---
+
+### Filter JSON
+
+#### Marshal filter to JSON
+
+```typescript
+const filter: FilterData = {
+  ids: ["abc123"],
+  kinds: [1],
+  tags: {
+    e: ["event-id"],
+  },
+  extensions: {
+    search: "nostr",
+  },
+};
+
+const jsonString = JSON.stringify(Filter.toJSON(filter));
+// Result: {"ids":["abc123"],"kinds":[1],"#e":["event-id"],"search":"nostr"}
+```
+
+#### Unmarshal filter from JSON
+
+```typescript
+const jsonData = `{
+  "authors": ["cfa87f35"],
+  "kinds": [1],
+  "#e": ["abc123"],
+  "since": 1234567890,
+  "search": "bitcoin"
+}`;
+
+const filter = Filter.fromJSON(JSON.parse(jsonData));
+
+// Standard fields populated: authors, kinds, since
+// Tag filters populated: tags.e = ["abc123"]
+// Unknown fields populated: extensions.search = "bitcoin"
+```
+
+#### Extensions field behavior
+
+The `extensions` field captures any JSON properties not recognized as standard filter fields or tag filters. This design allows the core library to remain frozen while storage and transport layers implement custom filtering behavior.
+
+**Standard fields**: `ids`, `authors`, `kinds`, `since`, `until`, `limit`
+
+**Tag filters**: Any key starting with `#` (e.g., `#e`, `#p`, `#emoji`)
+
+**Extensions**: Everything else
+
+During marshaling, extensions merge into the output JSON. During unmarshaling, unrecognized fields populate extensions. The `matches()` method ignores extensions, and the library expects higher protocol layers to implement their usage.
+
+Example implementing search filter:
+
+```typescript
+const filter: FilterData = {
+  kinds: [1],
+  extensions: {
+    search: "bitcoin",
+  },
+};
+
+// In a storage layer (not this library):
+if (filter.extensions?.search) {
+  const searchTerm = filter.extensions.search as string;
+  // Apply full-text search using searchTerm
+}
+```
+
+## Testing
+
+This library contains a comprehensive suite of unit tests. Run them with:
+
+```bash
+npm test
+```
+
+Or for a single run:
+
+```bash
+npm run test:run
+```