Merge pull request 'adopt_ASG_doc' (#12) from adopt_ASG_doc into v0.6.0-dev

Reviewed-on: #12

AI_prompt.md

@@ -143,11 +143,29 @@ Since I develop src folder before I adopt SDD_FRAMEWORK.md approach, can you che
 
 # ---------------------------------------------- 100 --------------------------------------------- #
 
-
+Check NATSBridge/docs folder I want to update the content of the following files according to ASG_Framework/ASG_Framework.md:
-
+- NATSBridge/docs/requirements.md
-
+- NATSBridge/docs/specification.md
-
+- NATSBridge/docs/ui-specification.md (you'll need to create this one)
-
+- NATSBridge/docs/walkthrough.md
+- NATSBridge/docs/architecture.md
+I'll do the other docs not listed here later myself.
+
+
+
+now help me update the following fileaccording to ASG_Framework/ASG_Framework.md:
+- NATSBridge/docs/specification.md
+
+
+<!-- ------------------------------------------- 100 ------------------------------------------- -->
+
+
+Check NATSBridge/docs folder. I would like to expand this package to include Dart support.
+Can you update the content of the following files according to ASG_Framework/ASG_Framework.md:
+- NATSBridge/docs/requirements.md
+- NATSBridge/docs/specification.md
+- NATSBridge/docs/walkthrough.md
+- NATSBridge/docs/architecture.md
 
 
 

Project.toml

@@ -1,6 +1,6 @@
 name = "NATSBridge"
 uuid = "f2724d33-f338-4a57-b9f8-1be882570d10"
-version = "0.5.5"
+version = "0.5.6"
 authors = ["narawat <narawat@gmail.com>"]
 
 [deps]

README.md

@@ -1,6 +1,6 @@
 # NATSBridge - Cross-Platform Bi-Directional Data Bridge
 
-A high-performance, bi-directional data bridge for **Julia, JavaScript, Python, and MicroPython** applications using NATS (Core & JetStream), implementing the Claim-Check pattern for large payloads.
+A high-performance, bi-directional data bridge for **Julia**, **JavaScript**, **Python**, and **MicroPython** applications using NATS (Core & JetStream), implementing the Claim-Check pattern for large payloads.
 
 [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)
 [![NATS](https://img.shields.io/badge/NATS-Enabled-green.svg)](https://nats.io)
@@ -28,8 +28,8 @@ NATSBridge enables seamless communication across multiple platforms through NATS
 
 | Transport | Payload Size | Method |
 |-----------|--------------|--------|
-| **Direct** | < 1MB | Sent directly via NATS (Base64 encoded) |
+| **Direct** | < 500KB | Sent directly via NATS (Base64 encoded) |
-| **Link** | >= 1MB | Uploaded to HTTP file server, URL sent via NATS |
+| **Link** | ≥ 500KB | Uploaded to HTTP file server, URL sent via NATS |
 
 ### Use Cases
 
@@ -45,9 +45,9 @@ NATSBridge enables seamless communication across multiple platforms through NATS
 | Platform | Implementation | Features |
 |----------|----------------|----------|
 | **Julia** | [`src/NATSBridge.jl`](src/NATSBridge.jl) | Full feature set, Arrow IPC, multiple dispatch |
-| **JavaScript** | [`src/natsbridge.js`](src/natsbridge.js) | Node.js, async/await |
+| **JavaScript (Node.js)** | [`src/natsbridge_ssr.js`](src/natsbridge_ssr.js) | Node.js, async/await, Arrow IPC |
-| **JavaScript (Browser)** | [`src/natsbridge_csr.js`](src/natsbridge_csr.js) | Browser, WebSocket NATS, async/await |
+| **JavaScript (Browser)** | [`src/natsbridge_csr.js`](src/natsbridge_csr.js) | Browser, WebSocket NATS, async/await, JSON table only |
-| **Python** | [`src/natsbridge.py`](src/natsbridge.py) | Desktop Python, asyncio, type hints |
+| **Python** | [`src/natsbridge.py`](src/natsbridge.py) | Desktop Python, asyncio, type hints, Arrow IPC |
 | **MicroPython** | [`src/natsbridge_mpy.py`](src/natsbridge_mpy.py) | Memory-constrained, synchronous API |
 
 ### Platform Comparison
@@ -57,7 +57,8 @@ NATSBridge enables seamless communication across multiple platforms through NATS
 | Multiple Dispatch | ✅ Native | ❌ | ❌ | ❌ | ❌ |
 | Async/Await | ❌ | ✅ Native | ✅ Native | ✅ Native | ⚠️ (uasyncio) |
 | Type Safety | ✅ Strong | ⚠️ (TypeScript) | ⚠️ (TypeScript) | ✅ (Type hints) | ❌ |
-| Arrow IPC | ✅ Native | ✅ | ✅ | ✅ | ❌ |
+| Arrow IPC | ✅ Native | ✅ Native | ❌ (Browser incompatible) | ✅ Native | ❌ |
+| JSON Table | ✅ | ✅ | ✅ (Only table type) | ✅ | ⚠️ (Limited) |
 | Direct Transport | ✅ | ✅ | ✅ | ✅ | ✅ |
 | Link Transport | ✅ | ✅ | ✅ | ✅ | ⚠️ (Limited) |
 | Handler Functions | ✅ | ✅ | ✅ | ✅ | ✅ |
@@ -72,8 +73,9 @@ NATSBridge enables seamless communication across multiple platforms through NATS
 - ✅ **Bi-directional messaging** with request-reply patterns
 - ✅ **Multi-payload support** - send multiple payloads with different types in one message
 - ✅ **Automatic transport selection** - direct vs link based on payload size
-- ✅ **Claim-Check pattern** for payloads > 1MB
+- ✅ **Claim-Check pattern** for payloads ≥ 500KB
-- ✅ **Apache Arrow IPC** support for tabular data (zero-copy reading)
+- ✅ **Apache Arrow IPC** support for tabular data (Desktop: Julia/Python/Node.js)
+- ✅ **JSON Table** support for tabular data (All platforms including Browser)
 - ✅ **Exponential backoff** for reliable file server downloads
 - ✅ **Correlation ID tracking** for message tracing
 - ✅ **Reply-to support** for request-response patterns
@@ -83,23 +85,24 @@ NATSBridge enables seamless communication across multiple platforms through NATS
 
 ## Quick Start
 
-### Step 1: Start NATS Server
+### Prerequisites
 
-```bash
+1. **NATS Server** - Install and run a NATS server:
-docker run -p 4222:4222 nats:latest
+   ```bash
-```
+   docker run -p 4222:4222 nats:latest
+   ```
 
-### Step 2: Start HTTP File Server (Optional)
+2. **HTTP File Server** (optional, for large payloads) - Install and run a file server:
+   ```bash
+   # Using Plik
+   docker run -p 8080:8080 -v /tmp/fileserver:/var/lib/plik -e PLIK_ADMIN_PASSWORD=admin plik/plik
+   
+   # OR using simple Python HTTP server
+   mkdir -p /tmp/fileserver
+   python3 -m http.server 8080 --directory /tmp/fileserver
+   ```
 
-```bash
+### Send Your First Message
-# Create a directory for file uploads
-mkdir -p /tmp/fileserver
-
-# Start HTTP file server
-python3 -m http.server 8080 --directory /tmp/fileserver
-```
-
-### Step 3: Send Your First Message
 
 #### Julia
 
@@ -107,14 +110,14 @@ python3 -m http.server 8080 --directory /tmp/fileserver
 using NATSBridge
 
 data = [("message", "Hello World", "text")]
-env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/room1", data; broker_url="nats://localhost:4222")
 println("Message sent!")
 ```
 
-#### JavaScript
+#### JavaScript (Node.js)
 
 ```javascript
-const NATSBridge = require('./src/natsbridge.js');
+import NATSBridge from './src/natsbridge_ssr.js';
 
 const data = [["message", "Hello World", "text"]];
 const [env, env_json_str] = await NATSBridge.smartsend(
@@ -125,6 +128,20 @@ const [env, env_json_str] = await NATSBridge.smartsend(
 console.log("Message sent!");
 ```
 
+#### JavaScript (Browser)
+
+```javascript
+import NATSBridge from './src/natsbridge_csr.js';
+
+const data = [["message", "Hello World", "text"]];
+const [env, env_json_str] = await NATSBridge.smartsend(
+    "/chat/room1",
+    data,
+    { broker_url: "ws://localhost:4222" }
+);
+console.log("Message sent!");
+```
+
 #### Python
 
 ```python
@@ -139,6 +156,21 @@ env, env_json_str = await smartsend(
 print("Message sent!")
 ```
 
+#### MicroPython
+
+```python
+from natsbridge import smartsend
+
+data = [("message", "Hello World", "text")]
+env, env_json_str = smartsend(
+    "/chat/room1",
+    data,
+    broker_url="nats://localhost:4222",
+    size_threshold=100000  # 100KB for MicroPython
+)
+print("Message sent!")
+```
+
 ---
 
 ## API Reference
@@ -147,13 +179,13 @@ print("Message sent!")
 
 All platforms use the same input/output format for payloads:
 
-**Input format for smartsend:**
+**Input format for `smartsend`:**
 ```
 [(dataname1, data1, type1), (dataname2, data2, type2), ...]
 ```
 
-**Output format for smartreceive:**
+**Output format for `smartreceive`:**
-```
+```json
 {
   "correlation_id": "...",
   "msg_id": "...",
@@ -187,7 +219,7 @@ env, env_json_str = NATSBridge.smartsend(
     broker_url::String = "nats://localhost:4222",
     fileserver_url = "http://localhost:8080",
     fileserver_upload_handler::Function = plik_oneshot_upload,
-    size_threshold::Int = 1_000_000,
+    size_threshold::Int = 500_000,
     correlation_id::String = string(uuid4()),
     msg_purpose::String = "chat",
     sender_name::String = "NATSBridge",
@@ -203,10 +235,10 @@ env, env_json_str = NATSBridge.smartsend(
 # Returns: ::Tuple{msg_envelope_v1, String}
 ```
 
-#### JavaScript
+#### JavaScript (Node.js)
 
 ```javascript
-const NATSBridge = require('natsbridge');
+import NATSBridge from './src/natsbridge_ssr.js';
 
 const [env, env_json_str] = await NATSBridge.smartsend(
     subject,
@@ -215,7 +247,36 @@ const [env, env_json_str] = await NATSBridge.smartsend(
         broker_url: 'nats://localhost:4222',
         fileserver_url: 'http://localhost:8080',
         fileserver_upload_handler: NATSBridge.plikOneshotUpload,
-        size_threshold: 1_000_000,
+        size_threshold: 500_000,
+        correlation_id: uuidv4(),
+        msg_purpose: 'chat',
+        sender_name: 'NATSBridge',
+        receiver_name: '',
+        receiver_id: '',
+        reply_to: '',
+        reply_to_msg_id: '',
+        is_publish: true,
+        nats_connection: null,
+        msg_id: uuidv4(),
+        sender_id: uuidv4()
+    }
+);
+// Returns: Promise<[env, env_json_str]>
+```
+
+#### JavaScript (Browser)
+
+```javascript
+import NATSBridge from './src/natsbridge_csr.js';
+
+const [env, env_json_str] = await NATSBridge.smartsend(
+    subject,
+    data,
+    {
+        broker_url: 'ws://localhost:4222',
+        fileserver_url: 'http://localhost:8080',
+        fileserver_upload_handler: NATSBridge.plikOneshotUpload,
+        size_threshold: 500_000,
         correlation_id: uuidv4(),
         msg_purpose: 'chat',
         sender_name: 'NATSBridge',
@@ -243,7 +304,7 @@ env, env_json_str = await NATSBridge.smartsend(
     broker_url: str = "nats://localhost:4222",
     fileserver_url: str = "http://localhost:8080",
     fileserver_upload_handler: Callable = plik_oneshot_upload,
-    size_threshold: int = 1_000_000,
+    size_threshold: int = 500_000,
     correlation_id: str = None,
     msg_purpose: str = "chat",
     sender_name: str = "NATSBridge",
@@ -293,9 +354,28 @@ env = NATSBridge.smartreceive(
 # Returns: ::JSON.Object{String, Any}
 ```
 
-#### JavaScript
+#### JavaScript (Node.js)
 
 ```javascript
+import NATSBridge from './src/natsbridge_ssr.js';
+
+const env = await NATSBridge.smartreceive(
+    msg,
+    {
+        fileserver_download_handler: NATSBridge.fetchWithBackoff,
+        max_retries: 5,
+        base_delay: 100,
+        max_delay: 5000
+    }
+);
+// Returns: Promise<env_object>
+```
+
+#### JavaScript (Browser)
+
+```javascript
+import NATSBridge from './src/natsbridge_csr.js';
+
 const env = await NATSBridge.smartreceive(
     msg,
     {
@@ -311,6 +391,8 @@ const env = await NATSBridge.smartreceive(
 #### Python
 
 ```python
+from natsbridge import NATSBridge
+
 env = await NATSBridge.smartreceive(
     msg,
     fileserver_download_handler=fetch_with_backoff,
@@ -324,6 +406,8 @@ env = await NATSBridge.smartreceive(
 #### MicroPython
 
 ```python
+from natsbridge import NATSBridge
+
 env = NATSBridge.smartreceive(
     msg,
     fileserver_download_handler=_sync_fileserver_download,
@@ -342,8 +426,8 @@ env = NATSBridge.smartreceive(
 |------|-------|------------|--------|-------------|-------------|
 | `text` | `String` | `string` | `str` | `str` | Plain text strings |
 | `dictionary` | `Dict`, `NamedTuple` | `Object`, `Array` | `dict`, `list` | `dict` | JSON-serializable dictionaries |
-| `arrowtable` | `DataFrame`, `Arrow.Table` | `Array<Object>` | `pandas.DataFrame` | ❌ | Tabular data (Arrow IPC) |
+| `arrowtable` | `DataFrame`, `Arrow.Table` | ❌ (Browser), ✅ (Node.js) | `pandas.DataFrame` | ❌ | Tabular data (Arrow IPC) |
-| `jsontable` | `Vector{NamedTuple}` | `Array<Object>` | `list[dict]` | ❌ | Tabular data (JSON) |
+| `jsontable` | `DataFrame`, `Vector{NamedTuple}` | `Array<Object>` | `list[dict]` | ⚠️ | Tabular data (JSON) - **Only table type in Browser** |
 | `image` | `Vector{UInt8}` | `Uint8Array`, `Buffer` | `bytes` | `bytearray` | Image data (PNG, JPG) |
 | `audio` | `Vector{UInt8}` | `Uint8Array`, `Buffer` | `bytes` | `bytearray` | Audio data (WAV, MP3) |
 | `video` | `Vector{UInt8}` | `Uint8Array`, `Buffer` | `bytes` | `bytearray` | Video data (MP4, AVI) |
@@ -368,13 +452,13 @@ data = [
     ("large_document", large_file_data, "binary")
 ]
 
-env, env_json_str = NATSBridge.smartsend("/chat/room1", data; fileserver_url="http://localhost:8080")
+env, env_json_str = smartsend("/chat/room1", data; fileserver_url="http://localhost:8080")
 ```
 
-#### JavaScript
+#### JavaScript (Node.js)
 
 ```javascript
-const NATSBridge = require('natsbridge');
+import NATSBridge from './src/natsbridge_ssr.js';
 
 const data = [
     ["message_text", "Hello!", "text"],
@@ -389,6 +473,24 @@ const [env, env_json_str] = await NATSBridge.smartsend(
 );
 ```
 
+#### JavaScript (Browser)
+
+```javascript
+import NATSBridge from './src/natsbridge_csr.js';
+
+const data = [
+    ["message_text", "Hello!", "text"],
+    ["user_avatar", imageData, "image"],
+    ["large_document", largeFileData, "binary"]
+];
+
+const [env, env_json_str] = await NATSBridge.smartsend(
+    "/chat/room1",
+    data,
+    { broker_url: 'ws://localhost:4222', fileserver_url: 'http://localhost:8080' }
+);
+```
+
 #### Python
 
 ```python
@@ -423,13 +525,13 @@ config = Dict(
 )
 
 data = [("config", config, "dictionary")]
-env, env_json_str = NATSBridge.smartsend("/device/config", data)
+env, env_json_str = smartsend("/device/config", data)
 ```
 
-#### JavaScript
+#### JavaScript (Node.js)
 
 ```javascript
-const NATSBridge = require('natsbridge');
+import NATSBridge from './src/natsbridge_ssr.js';
 
 const config = {
     wifi_ssid: "MyNetwork",
@@ -475,13 +577,13 @@ df = DataFrame(
 )
 
 data = [("students", df, "arrowtable")]
-env, env_json_str = NATSBridge.smartsend("/data/analysis", data)
+env, env_json_str = smartsend("/data/analysis", data)
 ```
 
-#### JavaScript
+#### JavaScript (Node.js)
 
 ```javascript
-const NATSBridge = require('natsbridge');
+import NATSBridge from './src/natsbridge_ssr.js';
 
 const df = [
     { id: 1, name: "Alice", score: 95 },
@@ -511,6 +613,26 @@ data = [("students", df, "arrowtable")]
 env, env_json_str = await NATSBridge.smartsend("/data/analysis", data)
 ```
 
+#### JavaScript (Browser)
+
+```javascript
+import NATSBridge from './src/natsbridge_csr.js';
+
+// Browser uses jsontable (JSON array of objects) instead of arrowtable
+// Apache Arrow is not compatible with browsers
+const df = [
+    { id: 1, name: "Alice", score: 95 },
+    { id: 2, name: "Bob", score: 88 },
+    { id: 3, name: "Charlie", score: 92 }
+];
+
+const [env, env_json_str] = await NATSBridge.smartsend(
+    "/data/analysis",
+    [["students", df, "jsontable"]],  // Use jsontable for browser
+    { broker_url: 'ws://localhost:4222' }
+);
+```
+
 ### Example 4: Request-Response Pattern
 
 Bi-directional communication with reply-to support.
@@ -521,18 +643,29 @@ Bi-directional communication with reply-to support.
 using NATSBridge
 
 # Requester
-env, env_json_str = NATSBridge.smartsend(
+env, env_json_str = smartsend(
     "/device/command",
     [("command", Dict("action" => "read_sensor"), "dictionary")];
     broker_url="nats://localhost:4222",
     reply_to="/device/response"
 )
+
+# Receiver (in separate application)
+msg = NATS.subscription.next()
+env = smartreceive(msg)
+# Process request and send response
+response_env, response_json = smartsend(
+    "/device/response",
+    [("result", Dict("value" => 42), "dictionary")],
+    reply_to="/device/command",
+    reply_to_msg_id=env["msg_id"]
+)
 ```
 
-#### JavaScript
+#### JavaScript (Node.js)
 
 ```javascript
-const NATSBridge = require('natsbridge');
+import NATSBridge from './src/natsbridge_ssr.js';
 
 // Requester
 const [env, env_json_str] = await NATSBridge.smartsend(
@@ -540,6 +673,16 @@ const [env, env_json_str] = await NATSBridge.smartsend(
     [["command", { action: "read_sensor" }, "dictionary"]],
     { broker_url: 'nats://localhost:4222', reply_to: '/device/response' }
 );
+
+// Receiver (in separate application)
+// const msg = await natsConsumer.next();
+// const env = await NATSBridge.smartreceive(msg);
+// Process request and send response
+// const response_env, response_json = await NATSBridge.smartsend(
+//     "/device/response",
+//     [["result", { value: 42 }, "dictionary"]],
+//     { reply_to: '/device/command', reply_to_msg_id: env.msg_id }
+// );
 ```
 
 #### Python
@@ -554,6 +697,17 @@ env, env_json_str = await NATSBridge.smartsend(
     broker_url="nats://localhost:4222",
     reply_to="/device/response"
 )
+
+# Receiver (in separate application)
+# msg = await nats_consumer.next()
+# env = await NATSBridge.smartreceive(msg)
+# Process request and send response
+# response_env, response_json = await NATSBridge.smartsend(
+#     "/device/response",
+#     [("result", {"value": 42}, "dictionary")],
+#     reply_to="/device/command",
+#     reply_to_msg_id=env["msg_id"]
+# )
 ```
 
 ---
@@ -636,14 +790,131 @@ python3 test/test_py_table_receiver.py
 
 ---
 
+## Browser Deployment
+
+### Using with Node.js Build Tools
+
+The browser implementation (`src/natsbridge_csr.js`) can be bundled for production deployment using modern JavaScript build tools.
+
+#### Prerequisites
+
+```bash
+# Install the browser-compatible NATS client
+npm install nats.ws
+```
+
+#### Vite (Recommended)
+
+```bash
+npm create vite@latest my-app -- --template vanilla
+cd my-app
+npm install nats.ws
+```
+
+In `vite.config.js`:
+```javascript
+import { defineConfig } from 'vite';
+export default defineConfig({
+  resolve: {
+    alias: {
+      'nats.ws': 'nats.ws/dist/esm/browser.js'
+    }
+  }
+});
+```
+
+Build command:
+```bash
+npm run build  # Outputs to dist/ folder
+```
+
+#### Webpack
+
+```bash
+npm install webpack webpack-cli --save-dev
+npm install nats.ws
+```
+
+In `webpack.config.js`:
+```javascript
+module.exports = {
+  entry: './src/index.js',
+  output: {
+    filename: 'bundle.js',
+    path: __dirname + '/dist'
+  },
+  resolve: {
+    alias: {
+      'nats.ws': 'nats.ws/dist/esm/browser.js'
+    }
+  }
+};
+```
+
+Build command:
+```bash
+npx webpack
+```
+
+#### esbuild (Simple & Fast)
+
+```bash
+npm install esbuild nats.ws --save-dev
+```
+
+Create `build.js`:
+```javascript
+import esbuild from 'esbuild';
+
+esbuild.buildSync({
+  entryPoints: ['src/natsbridge_csr.js'],
+  bundle: true,
+  outfile: 'dist/natsbridge-csr-bundle.js',
+  format: 'esm',
+  platform: 'browser',
+  target: 'es2020'
+});
+```
+
+Build command:
+```bash
+node build.js
+```
+
+### Using in Your HTML
+
+```html
+<!DOCTYPE html>
+<html>
+<head>
+  <title>My App</title>
+</head>
+<body>
+  <script type="module" src="dist/natsbridge-csr-bundle.js"></script>
+  <script type="module">
+    import NATSBridgeCSR from './dist/natsbridge-csr-bundle.js';
+    
+    // Use the library
+    const [env, envJson] = await NATSBridgeCSR.smartsend(
+      "/chat/user/v1/message",
+      [["msg", "Hello", "text"]],
+      { broker_url: "wss://nats.example.com" }
+    );
+  </script>
+</body>
+</html>
+```
+
+---
+
 ## Documentation
 
 For detailed architecture and implementation information, see:
 
-- [Architecture Documentation](docs/architecture_updated.md) - Cross-platform architecture, API parity, platform-specific patterns
+- [`docs/architecture.md`](docs/architecture.md) - Cross-platform architecture, API parity, platform-specific patterns
-- [Implementation Guide](docs/implementation_updated.md) - Detailed implementation for each platform, handler functions, testing
+- [`docs/requirements.md`](docs/requirements.md) - Business requirements and user stories
-- [Tutorial](docs/tutorial_updated.md) - Step-by-step getting started guide
+- [`docs/spec.md`](docs/spec.md) - Technical specification and contracts
-- [Walkthrough](docs/walkthrough_updated.md) - Real-world application building guides
+- [`docs/walkthrough.md`](docs/walkthrough.md) - Real-world application building guides
 
 ---
 

docs/SDD_FRAMEWORK.md

@@ -1,402 +0,0 @@
-# SDD + GitOps Documentation Framework
-
-This document defines the documentation framework for the NATSBridge project. It establishes a structured approach to creating, maintaining, and evolving technical documentation in alignment with GitOps principles—ensuring that documentation is versioned, auditable, and continuously validated alongside the codebase.
-
----
-
-## The SDD Framework: Seven Pillars of Documentation
-
-| Document | Purpose (Rationale) | Primary Audience | Format / Content | Example (SaaS Context) | Measurement (KPI) |
-|----------|---------------------|-----------------|------------------|------------------------|-------------------|
-| **Requirements** | Capture the **business intent** — why we're building this and what success looks like. Defines boundaries and user-visible outcomes. | Stakeholders, Product Owners, Lead Developers | User stories, PRDs, acceptance criteria, non-functional constraints. | "System must process tabular data from Julia to SvelteKit UI with <200ms latency for 5-member teams." | 95% of requests complete <200ms (synthetic monitoring). |
-| **Specification** | The **technical contract** — precise rules for inputs, outputs, and data shape. Ensures consistency across dev and test. | Developers, QA Engineers, CI/CD pipelines | OpenAPI, Protobuf, AsyncAPI. Endpoint definitions, schemas, error codes. | `contract.yaml` defining a NATS subject that accepts Arrow streams with snake_case headers. | 100% of messages validated against spec (CI block rate). |
-| **Architecture** | The **blueprint** — how components fit together, interact, and scale. Guides system structure and trade-offs. | Architects, Senior Developers, DevOps | C4 diagrams, Mermaid.js, component/network/storage models. | Diagram showing 6-node cluster routing traffic via Caddy → Node.js API → Julia pods. | 100% of major decisions logged with trade-off analysis. |
-| **Walkthrough** | The **story of flow** — shows how pieces connect end-to-end and why steps are sequenced. Builds intuition for new devs. | New Developers, Team Members | TOUR.md, Loom videos, sequence diagrams. Step-by-step traces with rationale. | "UI sends JSON → Node.js wraps Claim-Check → Julia pulls Arrow data (prevents NATS overflow)." | New developers ship feature in <2 days (PR timeline). |
-| **Implementation** | The **real code** — business logic, helpers, tests, configs. Where design becomes executable. | Developers, Code Reviewers | Source code, README.md, unit tests, setup scripts. | Julia function for matrix calculation + SvelteKit component rendering table. | >80% unit test coverage, <5% drift from spec. |
-| **Validation** | The **enforcer** — ensures implementation matches the spec. Blocks drift and human error. | Automation servers, QA, Lead Developers | CI jobs, contract tests, linting, integration checks. | CI job rejects PR with camelCase field not allowed by YAML spec. | <1% of PRs bypass validation gates. |
-| **Runbook** | The **operational manual** — how the system lives in production, scales, and recovers. Guides on-call engineers. | DevOps, SREs, On-call Developers | K8s manifests, Helm charts, Markdown guides. Deployment, scaling, backup/restore, troubleshooting. | GitOps manifest ensuring 6 Julia replicas restart if memory >80%. | MTTR <15 minutes for P1 incidents. |
-
----
-
-## Detailed Document Descriptions
-
-### 1. Requirements
-
-**Purpose**: Capture the *business intent* — why we're building this and what success looks like. Defines boundaries and user-visible outcomes.
-
-**Why It Matters**:
-- Aligns engineering efforts with business goals
-- Provides a north star for feature development
-- Establishes acceptance criteria before implementation begins
-- Creates a contract between product and engineering
-
-**Content Guidelines**:
-- User stories with clear acceptance criteria (As a X, I want Y so that Z)
-- Product Requirements Documents (PRDs) with success metrics
-- Non-functional requirements (performance, security, scalability)
-- Boundary definitions (what's in scope vs. out of scope)
-
-**Best Practices**:
-- Link each requirement to a measurable KPI
-- Keep requirements testable and verifiable
-- Maintain backward compatibility with existing requirements
-- Review and update requirements as business context changes
-
----
-
-### 2. Specification
-
-**Purpose**: The *technical contract* — precise rules for inputs, outputs, and data shape. Ensures consistency across dev and test.
-
-**Why It Matters**:
-- Prevents implementation drift between components
-- Enables contract testing in CI/CD pipelines
-- Provides a single source of truth for data structures
-- Facilitates integration between teams
-
-**Content Guidelines**:
-- API endpoint definitions (methods, paths, parameters)
-- Request/response schemas (JSON, XML, Protobuf, AsyncAPI)
-- Error codes and their meanings
-- Data validation rules and constraints
-- Rate limiting and quota definitions
-
-**Best Practices**:
-- Use formal specification languages (OpenAPI 3.0+, AsyncAPI)
-- Version specifications alongside code
-- Generate client SDKs from specifications
-- Block CI on specification violations
-- Document edge cases and error scenarios
-
----
-
-### 3. Architecture
-
-**Purpose**: The *blueprint* — how components fit together, interact, and scale. Guides system structure and trade-offs.
-
-**Why It Matters**:
-- Provides a mental model for system design
-- Guides technical decision-making and trade-off analysis
-- Facilitates onboarding of new architects and senior developers
-- Documents scaling and performance considerations
-
-**Content Guidelines**:
-- C4 diagrams (Context, Container, Component levels)
-- Mermaid.js flowcharts for sequence diagrams
-- Component interaction diagrams
-- Network topology and data flow
-- Storage and caching strategies
-- Scaling and resilience patterns
-
-**Best Practices**:
-- Use diagrams that are easy to update (Mermaid.js over static images)
-- Document trade-off decisions with Rationale Documents
-- Include scaling considerations for each component
-- Document failure modes and recovery strategies
-- Keep architecture diagrams versioned with code
-
----
-
-### 4. Walkthrough
-
-**Purpose**: The *story of flow* — shows how pieces connect end-to-end and why steps are sequenced. Builds intuition for new devs.
-
-**Why It Matters**:
-- Reduces onboarding time for new developers
-- Provides context that code comments alone cannot convey
-- Explains the "why" behind architectural decisions
-- Helps identify gaps in the system design
-
-**Content Guidelines**:
-- Step-by-step flow descriptions with rationale
-- Sequence diagrams showing request/response patterns
-- "Tour of the codebase" guides
-- Video walkthroughs (Loom, internal recordings)
-- Debugging and tracing examples
-
-**Best Practices**:
-- Walk through real user journeys, not just technical flows
-- Include "what could go wrong" scenarios
-- Link walkthroughs to relevant code locations
-- Keep walkthroughs updated with architecture changes
-- Make walkthroughs interactive where possible
-
----
-
-### 5. Implementation
-
-**Purpose**: The *real code* — business logic, helpers, tests, configs. Where design becomes executable.
-
-**Why It Matters**:
-- This is the actual artifact that runs in production
-- Code is the ultimate source of truth (when it matches spec)
-- Tests validate correctness and prevent regressions
-- Configuration files define runtime behavior
-
-**Content Guidelines**:
-- Business logic implementation
-- Helper functions and utilities
-- Unit and integration tests
-- Configuration files (YAML, JSON, environment)
-- Setup and development scripts
-- Code organization and module structure
-
-**Best Practices**:
-- Follow consistent code style and conventions
-- Write tests before or alongside implementation (TDD/BDD)
-- Document complex logic with inline comments
-- Keep configuration externalized and versioned
-- Use type annotations where applicable
-
----
-
-### 6. Validation
-
-**Purpose**: The *enforcer* — ensures implementation matches the spec. Blocks drift and human error.
-
-**Why It Matters**:
-- Prevents breaking changes from reaching production
-- Catches specification violations early in the CI pipeline
-- Maintains data integrity and API consistency
-- Reduces manual QA effort through automation
-
-**Content Guidelines**:
-- CI/CD pipeline configurations
-- Contract testing scripts
-- Linting rules and configurations
-- Integration test suites
-- Schema validation jobs
-- Security scanning and audit jobs
-
-**Best Practices**:
-- Fail CI on specification violations
-- Run validation jobs on every commit and PR
-- Use automated code review tools
-- Maintain validation job health dashboard
-- Document validation failure remediation steps
-
----
-
-### 7. Runbook
-
-**Purpose**: The *operational manual* — how the system lives in production, scales, and recovers. Guides on-call engineers.
-
-**Why It Matters**:
-- Reduces Mean Time To Recovery (MTTR) for incidents
-- Provides step-by-step guidance for common issues
-- Documents scaling and deployment procedures
-- Ensures operational knowledge is not siloed
-
-**Content Guidelines**:
-- Deployment procedures (manual and automated)
-- Scaling instructions (horizontal/vertical)
-- Backup and restore procedures
-- Troubleshooting guides for common issues
-- Runbook entries for specific error codes
-- Contact information and escalation paths
-
-**Best Practices**:
-- Write runbooks for every P1/P2 incident
-- Include exact commands and configuration snippets
-- Test runbooks periodically (chaos engineering)
-- Link runbook entries to relevant documentation
-- Keep runbooks updated when system changes
-
----
-
-## How to Use This Approach Effectively
-
-### 1. Start with Requirements
-
-Before writing any code or documentation, establish clear requirements. Ask:
-- What business problem are we solving?
-- How will we measure success?
-- What are the non-negotiable constraints?
-
-**Action**: Create a `docs/requirements/` directory and start with `PRD.md` and `KPIs.md`.
-
-### 2. Define the Specification First
-
-Once requirements are stable, define the technical specification. This becomes the contract for implementation.
-
-**Action**: Create `docs/specification/` with `contract.yaml` (or appropriate format) and `error-codes.md`.
-
-### 3. Design the Architecture
-
-With requirements and specification in place, design the architecture. Document trade-off decisions explicitly.
-
-**Action**: Create `docs/architecture/` with Mermaid diagrams and `trade-offs.md`.
-
-### 4. Create Walkthroughs Early
-
-As soon as the architecture is defined, create walkthroughs. This helps identify gaps and provides onboarding material.
-
-**Action**: Create `docs/walkthrough/` with `TOUR.md` and sequence diagrams.
-
-### 5. Implement with Validation in Mind
-
-Write implementation code that adheres to the specification. Build validation into the CI pipeline from day one.
-
-**Action**: Ensure test files are co-located with implementation and run on every commit.
-
-### 6. Automate Validation
-
-Build automated validation that runs in CI/CD. This ensures spec compliance and prevents drift.
-
-**Action**: Configure CI jobs to validate against specification and block PRs on violations.
-
-### 7. Document Operations from Day One
-
-Create runbook entries as soon as deployment procedures are established. Update them when incidents occur.
-
-**Action**: Create `docs/runbook/` with entries for deployment, scaling, and common issues.
-
----
-
-## GitOps Integration
-
-This documentation framework aligns with GitOps principles:
-
-| GitOps Principle | Documentation Alignment |
-|-----------------|------------------------|
-| **Versioned** | All documentation lives in git, with history and audit trail |
-| ** declarative** | Specifications and architecture are declarative contracts |
-| **Automated** | Validation jobs automate spec compliance checks |
-| **Self-Service** | Walkthroughs and runbooks enable self-service onboarding and operations |
-| **Observability** | KPIs and metrics are defined for each documentation artifact |
-
-**Git Structure**:
-```
-docs/
-├── requirements/       # PRDs, user stories, KPIs
-├── specification/      # OpenAPI, Protobuf, AsyncAPI specs
-├── architecture/       # C4 diagrams, Mermaid, trade-off docs
-├── walkthrough/        # TOUR.md, sequence diagrams
-├── implementation/     # Source code (in src/)
-├── validation/         # CI configs, test suites
-└── runbook/            # Deployment, scaling, troubleshooting
-```
-
----
-
-## Metrics and Continuous Improvement
-
-Each documentation artifact has associated KPIs. Track these to ensure quality:
-
-| Document | KPI | Target |
-|----------|-----|--------|
-| Requirements | Requirement coverage | 100% of features have associated requirements |
-| Specification | Spec compliance rate | 100% of messages validate against spec |
-| Architecture | Decision documentation | 100% of major decisions logged with trade-offs |
-| Walkthrough | New dev time-to-first-PR | <2 days from onboarding to first contribution |
-| Implementation | Test coverage | >80% unit test coverage |
-| Validation | Bypass rate | <1% of PRs bypass validation gates |
-| Runbook | MTTR | <15 minutes for P1 incidents |
-
-**Review Cadence**:
-- Weekly: Review KPI dashboards and documentation gaps
-- Monthly: Update documentation based on incident learnings
-- Quarterly: Full framework review and improvement
-
----
-
-## Template Examples
-
-### Requirements Template
-```markdown
-# PRD: Feature Name
-
-## Business Goal
-[What problem are we solving?]
-
-## Success Metrics
-- [Metric 1]: Target [value]
-- [Metric 2]: Target [value]
-
-## User Stories
-- As a [role], I want [feature] so that [benefit]
-  - Acceptance Criteria: [details]
-
-## Non-Functional Requirements
-- Performance: [details]
-- Security: [details]
-- Scalability: [details]
-
-## Out of Scope
-- [What's explicitly excluded]
-```
-
-### Specification Template
-```yaml
-# contract.yaml
-openapi: 3.0.0
-info:
-  title: NATSBridge API
-  version: 1.0.0
-paths:
-  /api/v1/endpoint:
-    post:
-      requestBody:
-        content:
-          application/json:
-            schema:
-              $ref: '#/components/schemas/Request'
-      responses:
-        '200':
-          description: Success
-          content:
-            application/json:
-              schema:
-                $ref: '#/components/schemas/Response'
-```
-
-### Architecture Template
-```mermaid
-%%{init: {'theme': 'base', 'themeVariables': {'primaryColor': '#3b82f6'}}}%%
-flowchart TD
-    A[Client] --> B[Caddy]
-    B --> C[Node.js API]
-    C --> D[Julia Worker]
-    D --> E[NATS Cluster]
-    E --> F[Storage]
-    
-    style A fill:#f9f9f9,stroke:#333
-    style E fill:#e0e7ff,stroke:#3b82f6
-```
-
-### Runbook Template
-```markdown
-# Runbook: Service Restart
-
-**Severity**: P2
-**Estimated Time**: 5 minutes
-
-## Symptoms
-- Service is unresponsive
-- Health checks are failing
-
-## Steps
-1. SSH to the host
-2. Run: `kubectl rollout restart deployment/natsbridge`
-3. Monitor: `kubectl get pods -l app=natsbridge -w`
-
-## Rollback
-- Run: `kubectl rollout undo deployment/natsbridge`
-
-## Post-Incident
-- [ ] Review logs for root cause
-- [ ] Update runbook if needed
-```
-
----
-
-## Conclusion
-
-This SDD + GitOps Documentation Framework ensures that documentation is:
-- **Structured**: Seven distinct artifacts with clear purposes
-- **Automated**: Validation and CI/CD integration
-- **Versioned**: All documentation in git with history
-- **Measurable**: KPIs for quality and effectiveness
-- **Actionable**: Practical templates and examples
-
-Use this framework as a living document—update it as your team's needs evolve.

docs/architecture.md

@@ -1,16 +1,16 @@
 # Architecture Documentation: NATSBridge
 
-**Version**: 1.0.0  
+**Version**: 1.1.0  
-**Date**: 2026-03-13  
+**Date**: 2026-03-23  
 **Status**: Active  
 **Ground Truth**: [`src/NATSBridge.jl`](../src/NATSBridge.jl)  
 **Architecture Level**: C4 Container Level
 
 ---
 
-## Executive Summary
+## 1. Executive Summary
 
-This document defines the **blueprint** for NATSBridge - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, and **MicroPython** applications using NATS as the message bus.
+This document defines the **blueprint** for NATSBridge - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, and **MicroPython** applications using NATS as the message bus.
 
 This architecture document serves as the single source of truth for:
 - **System Structure**: How components fit together and interact
@@ -18,8 +18,29 @@ This architecture document serves as the single source of truth for:
 - **Failure Modes**: How the system handles failures and recovers
 - **Trade-off Decisions**: The rationale behind architectural decisions
 
+### 1.1 Specification Traceability
+
+| Architecture Section | Specification Reference | UI Specification Reference | Requirement ID(s) |
+|---------------------|-------------------------|---------------------------|-------------------|
+| Section 2 (Context Diagram) | specification.md:2 | - | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-012, FR-013, FR-014 |
+| Section 3 (Container Diagram) | specification.md:2, specification.md:3, specification.md:11 | - | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-012, FR-013, FR-014 |
+| Section 4 (Component Diagram) | specification.md:2, specification.md:3, specification.md:5, specification.md:11 | - | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-012, FR-013, FR-014 |
+| Section 5 (High-Level) | specification.md:2, specification.md:3, specification.md:5, specification.md:11 | - | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-012, FR-013, FR-014 |
+| Section 6 (Message Envelope) | specification.md:2, specification.md:3, specification.md:8 | - | FR-011, FR-012, FR-013, FR-014, NFR-401, NFR-403 |
+| Section 7 (Payload Type) | specification.md:3, specification.md:5, specification.md:6 | - | FR-001, FR-002, FR-003, FR-006, FR-012, NFR-101, NFR-102 |
+| Section 8 (Transport Strategy) | specification.md:6, specification.md:7 | - | FR-003, FR-004, FR-005, FR-010, NFR-104, NFR-105, NFR-106 |
+| Section 9 (Platform-Specific) | specification.md:13, specification.md:14 | - | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-012, FR-013, FR-014 |
+| Section 10 (Scaling) | specification.md:7, specification.md:13 | - | NFR-101, NFR-102, NFR-103, NFR-104, NFR-105, NFR-106, NFR-107 |
+| Section 11 (Failure Modes) | specification.md:9, specification.md:11 | - | FR-008, FR-009, FR-010, FR-011, NFR-201, NFR-202, NFR-203 |
+| Section 12 (Trade-offs) | specification.md:2, specification.md:3, specification.md:6, specification.md:7 | - | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-008, FR-009, FR-010, FR-011, FR-012, FR-013, FR-014 |
+| Section 13 (Deployment) | specification.md:12, specification.md:18 | - | FR-013, FR-014, NFR-201, NFR-203 |
+| Section 14 (Security) | specification.md:4, specification.md:9, specification.md:12 | - | NFR-301, NFR-302, NFR-303, NFR-401, NFR-402, NFR-403, NFR-404, NFR-405 |
+| Section 15 (Testing) | specification.md:17 | - | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-012, FR-013, FR-014 |
+
 ---
 
+## 2. Architecture Overview
+
 ## Architecture Overview
 
 ### C4 Context Diagram
@@ -35,17 +56,20 @@ flowchart TD
         Julia_App[Julia Application]
         JS_App[JavaScript Application<br/>Node.js/Browser]
         Python_App[Python Application<br/>Desktop]
+        Dart_App[Dart Application<br/>Desktop/Flutter/Web]
         MicroPython_App[MicroPython Device]
     end
 
     Julia_App -->|NATS| NATS_Server
     JS_App -->|NATS| NATS_Server
     Python_App -->|NATS| NATS_Server
+    Dart_App -->|NATS| NATS_Server
     MicroPython_App -->|NATS| NATS_Server
 
     Julia_App -->|HTTP| File_Server
     JS_App -->|HTTP| File_Server
     Python_App -->|HTTP| File_Server
+    Dart_App -->|HTTP| File_Server
     MicroPython_App -->|HTTP| File_Server
 
     style NATS_Server fill:#fff3e0,stroke:#f57c00
@@ -53,6 +77,7 @@ flowchart TD
     style Julia_App fill:#e8f5e9,stroke:#4caf50
     style JS_App fill:#e3f2fd,stroke:#2196f3
     style Python_App fill:#e3f2fd,stroke:#2196f3
+    style Dart_App fill:#fff0f6,stroke:#e91e63
     style MicroPython_App fill:#fce4ec,stroke:#e91e63
 ```
 
@@ -64,6 +89,7 @@ flowchart TD
         Julia_Module[Julia NATSBridge Module]
         JS_Module[JavaScript NATSBridge Module]
         Python_Module[Python NATSBridge Module]
+        Dart_Module[Dart NATSBridge Module]
         MicroPython_Module[MicroPython NATSBridge Module]
     end
 
@@ -80,6 +106,7 @@ flowchart TD
     Julia_Module --> NATS_Client
     JS_Module --> NATS_Client
     Python_Module --> NATS_Client
+    Dart_Module --> NATS_Client
     MicroPython_Module --> NATS_Client
 
     NATS_Client --> NATS_Broker
@@ -87,6 +114,7 @@ flowchart TD
     Julia_Module --> File_Client
     JS_Module --> File_Client
     Python_Module --> File_Client
+    Dart_Module --> File_Client
     MicroPython_Module --> File_Client
 
     File_Client --> File_Server
@@ -94,6 +122,7 @@ flowchart TD
     style Julia_Module fill:#e8f5e9,stroke:#4caf50
     style JS_Module fill:#e3f2fd,stroke:#2196f3
     style Python_Module fill:#e3f2fd,stroke:#2196f3
+    style Dart_Module fill:#fff0f6,stroke:#e91e63
     style MicroPython_Module fill:#fce4ec,stroke:#e91e63
     style NATS_Broker fill:#fff3e0,stroke:#f57c00
     style File_Server fill:#f3e5f5,stroke:#9c27b4
@@ -159,8 +188,8 @@ flowchart TD
 | **_build_envelope** | Build message envelope from payloads | All |
 | **_build_payload** | Build payload object from serialized data | All |
 | **publish_message** | Publish message to NATS subject | All |
-| **fileserver_upload_handler** | Upload large payloads to HTTP server | Desktop |
+| **fileserver_upload_handler** | Upload large payloads to HTTP server | Desktop (Julia/JS/Python/Dart) |
-| **fileserver_download_handler** | Download payloads from HTTP server | Desktop |
+| **fileserver_download_handler** | Download payloads from HTTP server | Desktop (Julia/JS/Python/Dart) |
 
 ### Data Flow
 
@@ -275,8 +304,8 @@ end
 |------|-------------|---------------|----------|-----------|
 | `text` | Plain text string | UTF-8 bytes | Base64 | All |
 | `dictionary` | JSON object | JSON string | Base64/JSON | All |
-| `arrowtable` | Apache Arrow IPC | Arrow IPC stream | Base64/arrow-ipc | Desktop |
+| `arrowtable` | Apache Arrow IPC | Arrow IPC stream | Base64/arrow-ipc | Desktop (Julia/Python/Node.js/Dart) |
-| `jsontable` | JSON array of objects | JSON string | Base64/json | All |
+| `jsontable` | JSON array of objects | JSON string | Base64/json | All (including Browser/Dart Web) |
 | `image` | Binary image data | Raw bytes | Base64 | All |
 | `audio` | Binary audio data | Raw bytes | Base64 | All |
 | `video` | Binary video data | Raw bytes | Base64 | All |
@@ -318,7 +347,10 @@ flowchart TD
 
 | Platform | Size Threshold | Notes |
 |----------|----------------|-------|
-| Desktop (Julia/JS/Python) | 500,000 bytes (0.5MB) | Default threshold |
+| Desktop (Julia/JS/Python/Dart) | 500,000 bytes (0.5MB) | Default threshold |
+| Dart Desktop | 500,000 bytes (0.5MB) | Default threshold |
+| Dart Flutter | 500,000 bytes (0.5MB) | Default threshold |
+| Dart Web | 500,000 bytes (0.5MB) | Default threshold |
 | MicroPython | 100,000 bytes (100KB) | Lower threshold for memory constraints |
 
 ### Transport Selection Flow
@@ -405,21 +437,68 @@ end
 
 JavaScript uses async/await for non-blocking I/O:
 
-- **Class-based NATS Client**: Connection management
+- **Class-based NATS Client**: Connection management with `keepAlive` support
 - **Module-level Utilities**: Serialization functions
-- **Native ArrayBuffer**: Binary data handling
+- **Native ArrayBuffer**: Binary data handling (Browser) / Buffer (Node.js)
 - **Fetch API**: HTTP file server communication
+- **Connection Pooling**: `NATSConnectionPool` for high-throughput scenarios
+
+#### Node.js Implementation (natsbridge_ssr.js)
+
+- **TCP NATS connections**: Uses `nats://` or `tls://` URLs
+- **Apache Arrow IPC**: Full support via `apache-arrow`
+- **Buffer for binary data**: Native Node.js Buffer handling
 
 ```javascript
-// Class-based NATS client
+// Class-based NATS client with keepAlive support
 class NATSClient {
-    constructor(url) {
+    constructor(url, keepAlive = false) {
         this.url = url;
         this.connection = null;
+        this.keepAlive = keepAlive;
     }
     
     async connect() {
+        if (this.connection) return this.connection;
         this.connection = await nats.connect({ servers: this.url });
+        return this.connection;
+    }
+}
+
+// Connection pool for managing multiple connections
+class NATSConnectionPool {
+    constructor(url, maxSize = 10) {
+        this.url = url;
+        this.maxSize = maxSize;
+        this.connections = new Map();
+    }
+    
+    async acquire() { /* Get or create connection */ }
+    release(client) { /* Return to pool or close */ }
+    async closeAll() { /* Close all pool connections */ }
+}
+```
+
+#### Browser Implementation (natsbridge_csr.js)
+
+- **WebSocket NATS connections**: Uses `ws://` or `wss://` URLs via `nats.ws`
+- **No Apache Arrow**: Uses `jsontable` for tabular data only
+- **Uint8Array for binary data**: Browser-compatible binary handling
+- **Web Crypto API**: UUID generation via `crypto.getRandomValues()`
+
+```javascript
+// Class-based NATS client with keepAlive support
+class NATSClient {
+    constructor(url, keepAlive = false) {
+        this.url = url;  // ws:// or wss://
+        this.connection = null;
+        this.keepAlive = keepAlive;
+    }
+    
+    async connect() {
+        if (this.connection) return this.connection;
+        this.connection = await nats.connect({ servers: this.url });
+        return this.connection;
     }
 }
 ```
@@ -442,6 +521,60 @@ class NATSBridge:
         self.fileserver_url = fileserver_url or self.DEFAULT_FILESERVER_URL
 ```
 
+### Dart Architecture
+
+Dart uses classes for stateful operations with async/await:
+
+- **Class-based NATSBridge**: Encapsulated API
+- **Data classes**: Structured data (MsgPayloadV1, MsgEnvelopeV1)
+- **Async/await**: I/O operations
+- **dart-arrow**: Arrow IPC support (Desktop/Flutter only)
+- **HTTP package**: HTTP file server communication
+- **nats package**: NATS client with WebSocket support (Dart Web)
+
+```dart
+class NATSBridge {
+  static const DEFAULT_SIZE_THRESHOLD = 500000;
+  
+  final String brokerUrl;
+  final String fileserverUrl;
+  
+  NATSBridge({
+    this.brokerUrl = 'nats://localhost:4222',
+    this.fileserverUrl = 'http://localhost:8080',
+  });
+}
+```
+
+#### Dart Desktop (Dart SDK)
+
+- **TCP NATS connections**: Uses `nats://` or `tls://` URLs
+- **Apache Arrow IPC**: Full support via `dart-arrow`
+- **Uint8List for binary data**: Native Dart binary handling
+
+#### Dart Flutter (Dart SDK)
+
+- **TCP NATS connections**: Uses `nats://` or `tls://` URLs
+- **Apache Arrow IPC**: Full support via `dart-arrow`
+- **Uint8List for binary data**: Native Dart binary handling
+
+#### Dart Web (Dart SDK)
+
+- **WebSocket NATS connections**: Uses `ws://` or `wss://` URLs via `nats` package
+- **No Apache Arrow**: Uses `jsontable` for tabular data only
+- **Uint8List for binary data**: Browser-compatible binary handling
+- **Fetch API**: HTTP file server communication via `http` package
+
+### Browser Architecture
+
+Browser JavaScript has specific constraints due to security and compatibility:
+
+- **Async/await**: Native async/await support
+- **No Apache Arrow**: Arrow IPC not available in browsers
+- **JSON table only**: Use "jsontable" for tabular data
+- **WebSocket NATS**: Uses nats.ws for browser-compatible NATS connections
+- **Fetch API**: HTTP file server communication via fetch
+
 ### MicroPython Architecture
 
 MicroPython has significant constraints:
@@ -598,7 +731,7 @@ MAX_PAYLOAD_SIZE = 50_000  # 50KB hard limit
 |-----------|---------|-------|
 | NATS Server | 1 instance | Single node for development |
 | File Server | 1 instance | HTTP server for large payloads |
-| Client Memory | 50MB | Desktop platforms |
+| Client Memory | 50MB | Desktop platforms (Julia/JS/Python/Dart) |
 | Client Memory | 256KB | MicroPython devices |
 
 ### Environment Variables
@@ -693,7 +826,7 @@ flowchart TD
 
 | Version | Supported Platforms |
 |---------|---------------------|
-| v1.0.x | Julia 1.7+, Node.js 16+, Python 3.8+, MicroPython 1.19+ |
+| v1.0.x | Julia 1.7+, Node.js 16+, Python 3.8+, Dart 2.17+, MicroPython 1.19+ |
 
 ---
 
@@ -701,16 +834,85 @@ flowchart TD
 
 | Date | Version | Changes |
 |------|---------|---------|
+| 2026-03-15 | 1.1.0 | JavaScript connection management |
+| - | - | Added NATSClient with keepAlive support |
+| - | - | Added NATSConnectionPool for connection reuse |
+| - | - | Added publishMessage function with closeConnection option |
 | 2026-03-13 | 1.0.0 | Initial architecture documentation |
 
 ---
 
-## References
+## 16. References
 
-- [`docs/requirements.md`](./requirements.md) - Business requirements and user stories
+### 16.1 Documentation Artifacts
-- [`docs/spec.md`](./spec.md) - Technical specification and contracts
+
-- [`src/NATSBridge.jl`](../src/NATSBridge.jl) - Ground truth implementation
+| Document | Purpose | Specification Traceability | UI Specification Traceability | Requirement ID(s) |
-- [`README.md`](../README.md) - Project overview
+|----------|---------|---------------------------|------------------------------|-------------------|
+| [`docs/requirements.md`](./requirements.md) | Business requirements and user stories | FR-001 through FR-014, NFR-101 through NFR-405 | - | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`docs/specification.md`](./specification.md) | Technical contract for NATSBridge | specification.md:2-19 (all sections) | - | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`docs/ui-specification.md`](./ui-specification.md) | UI specification for client applications | - | All UI components and interactions | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`docs/walkthrough.md`](./walkthrough.md) | End-to-end system flow | specification.md:2-19 (all sections) | - | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`docs/architecture.md`](./architecture.md) | System architecture diagrams | specification.md:2-19 (all sections) | - | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`docs/validation.md`](./validation.md) | CI/CD validation rules | specification.md:2-19 (all sections) | - | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`docs/runbook.md`](./runbook.md) | Operational runbook | specification.md:2-19 (all sections) | - | FR-001 through FR-014, NFR-101 through NFR-405 |
+
+### 16.2 Implementation Files
+
+| File | Platform | Features | Specification Traceability | Requirement ID(s) |
+|------|----------|----------|---------------------------|-------------------|
+| [`src/NATSBridge.jl`](../src/NATSBridge.jl) | Julia | Full feature set, Arrow IPC, multiple dispatch | specification.md:2-19 (all sections) | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/natsbridge_ssr.js`](../src/natsbridge_ssr.js) | Node.js | Arrow IPC, async/await | specification.md:2-19 (all sections) | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/natsbridge_csr.js`](../src/natsbridge_csr.js) | Browser | JSON table only, WebSocket NATS | specification.md:2-19 (all sections) | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/natsbridge.py`](../src/natsbridge.py) | Python | Arrow IPC, async/await | specification.md:2-19 (all sections) | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/natsbridge.dart`](../src/natsbridge.dart) | Dart | Full feature set, Arrow IPC, async/await | specification.md:2-19 (all sections) | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/natsbridge_mpy.py`](../src/natsbridge_mpy.py) | MicroPython | Limited to direct transport | specification.md:2-19 (all sections) | FR-005, FR-006, FR-012 |
+
+### 16.3 External Dependencies
+
+| Platform | Package | Version | Purpose | Specification Traceability | Requirement ID(s) |
+|----------|---------|---------|---------|---------------------------|-------------------|
+| Julia | NATS.jl | Latest | NATS client | specification.md:11 | FR-013, FR-014, NFR-201 |
+| Julia | JSON.jl | Latest | JSON serialization | specification.md:11 | FR-012, NFR-101, NFR-102 |
+| Julia | Arrow.jl | Latest | Arrow IPC support | specification.md:11 | FR-002, FR-012 |
+| Julia | HTTP.jl | Latest | HTTP file server | specification.md:11 | FR-008, FR-009 |
+| Julia | UUIDs.jl | Latest | UUID generation | specification.md:11 | FR-011, NFR-401 |
+| Node.js | nats | Latest | NATS client (TCP) | specification.md:11 | FR-013, FR-014 |
+| Node.js | node-fetch | Latest | HTTP file server | specification.md:11 | FR-008, FR-009 |
+| Browser | nats.ws | Latest | NATS client (WebSocket) | specification.md:11 | FR-013, FR-014 |
+| Browser | nats | Latest | NATS client (for bundling) | specification.md:11 | FR-013, FR-014 |
+| Python | nats-py | Latest | NATS client | specification.md:11 | FR-013, FR-014 |
+| Python | aiohttp | Latest | HTTP file server | specification.md:11 | FR-008, FR-009 |
+| Python | pyarrow | Latest | Arrow IPC support | specification.md:11 | FR-002, FR-012 |
+| Dart | nats | Latest | NATS client | specification.md:11 | FR-013, FR-014 |
+| Dart | http | Latest | HTTP file server | specification.md:11 | FR-008, FR-009 |
+| Dart | uuid | Latest | UUID generation | specification.md:11 | FR-011, NFR-401 |
+| Dart | dart-arrow | Latest | Arrow IPC support | specification.md:11 | FR-002, FR-012 |
+| MicroPython | builtin | N/A | Limited implementation | specification.md:11 | FR-005, FR-006, FR-012 |
+
+---
+
+## 17. Change Log
+
+| Date | Version | Changes | Specification Reference |
+|------|---------|---------|------------------------|
+| 2026-03-23 | 1.1.0 | Updated to ASG Framework architecture guidelines | specification.md:2-19 (all sections) |
+| 2026-03-15 | 1.1.0 | JavaScript connection management | specification.md:2-19 (all sections) |
+| 2026-03-13 | 1.0.0 | Initial architecture documentation | specification.md:2-19 (all sections) |
+
+---
+
+## 18. Gap-Check Validation
+
+| Stage Transition | Gap-Check Question | Status |
+|------------------|-------------------|--------|
+| Requirements → Specification | Does the Specification define all edge cases and conflict scenarios from the Requirements? | ✅ Verified - All FR-XXX requirements have corresponding spec rules |
+| Specification → UI Specification | Does the UI Specification expose all the data and states defined in the Specification? | ⏳ Pending - UI spec not yet created |
+| UI Specification → Walkthrough | Does the Walkthrough reflect the complete flow including error states and timing? | ⏳ Pending - UI spec not yet created |
+| Walkthrough → Architecture | Does the Architecture support the performance and integration requirements defined in the Walkthrough? | ✅ Verified - Architecture supports all walkthrough flows |
+
+---
+
+*This architecture document is versioned and maintained in git alongside the codebase. All implementations must adhere to this architecture.*
 
 ---
 

docs/requirements.md

@@ -1,33 +1,38 @@
 # Requirements Document: NATSBridge
 
 **Version**: 1.0.0  
-**Date**: 2026-03-13  
+**Date**: 2026-03-23  
 **Status**: Active  
 **Ground Truth**: [`src/NATSBridge.jl`](../src/NATSBridge.jl)
 
 ---
 
-## Executive Summary
+## 1. Business Context & Success Metrics
 
-NATSBridge is a cross-platform, bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, and **MicroPython** applications using NATS as the message bus. The system implements the **Claim-Check pattern** for efficient handling of large payloads (>0.5MB) by uploading them to an HTTP file server instead of sending raw binary data over NATS.
+### 1.1 Business Goal
 
----
+NATSBridge is a cross-platform, bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, and **MicroPython** applications using NATS as the message bus. The system implements the **Claim-Check pattern** for efficient handling of large payloads (>0.5MB) by uploading them to an HTTP file server instead of sending raw binary data over NATS.
 
-## Business Goals
+### 1.2 User Stories (with acceptance criteria)
 
-### Primary Objectives
+| Story | Priority | Acceptance Criteria |
+|-------|----------|---------------------|
+| **As a Julia developer**, I want to send text messages to JavaScript/Dart applications that lives on a server and also on a browser | P1 | Text messages are serialized, encoded, and received correctly across platforms |
+| **As a Python developer**, I want to send tabular data to Julia/Dart applications | P1 | DataFrame exchange works with both Arrow IPC and JSON formats |
+| **As a JavaScript developer**, I want to send large files (>0.5MB) from JavaScript applications that lives on a server and also on a browser to other applications | P1 | Large files are automatically uploaded to file server and URLs are sent via NATS |
+| **As a Dart developer**, I want to send text messages to other platforms | P1 | Text messages are serialized, encoded, and received correctly across platforms |
+| **As a Dart developer**, I want to send dictionary data to other platforms | P1 | JSON-serializable data is exchanged correctly |
+| **As a Dart developer**, I want to send tabular data (List<Map>) to other platforms | P1 | JSON table format exchange works with Arrow IPC on desktop |
+| **As a Dart developer**, I want to send large files (>0.5MB) | P1 | Large files are automatically uploaded to file server and URLs are sent via NATS |
+| **As a MicroPython developer**, I want to send sensor data with minimal memory usage | P1 | Direct transport works for payloads <100KB on memory-constrained devices |
+| **As a developer**, I want to send mixed-content messages (text + image + file) | P1 | NATSBridge accepts list of (dataname, data, type) tuples and handles each payload appropriately |
+| **As a developer**, I want to receive multi-payload messages | P1 | NATSBridge returns payloads as list of tuples with correct types preserved |
+| **As a developer**, I want to use Plik as the file server | P2 | Plik one-shot upload mode is supported with upload ID and token handling |
+| **As a developer**, I want to use custom HTTP file servers | P2 | Handler function abstraction allows plugging in AWS S3 or custom implementations |
+| **As a developer**, I want automatic retry on file server download failures | P1 | Exponential backoff with configurable retries (default: 5, base_delay: 100ms, max_delay: 5000ms) |
+| **As a developer**, I want message tracing across distributed systems | P1 | Correlation ID is propagated through all message processing steps |
 
-1. **Cross-Platform Interoperability**: Enable seamless data exchange between Julia, JavaScript (for both Server-Side rendering and Client-Side rendering webapp), Python, and MicroPython applications without platform-specific barriers.
+### 1.3 KPIs & Targets
-
-2. **Efficient Large Payload Handling**: Implement intelligent transport selection based on payload size:
-   - **Direct Transport**: Small payloads (<0.5MB) sent directly via NATS
-   - **Link Transport**: Large payloads (≥0.5MB) uploaded to HTTP file server, URL sent via NATS
-
-3. **Unified API Across Platforms**: Provide consistent `smartsend()` and `smartreceive()` functions across all supported platforms while maintaining idiomatic implementations.
-
-4. **Developer Productivity**: Reduce onboarding time and simplify integration through comprehensive documentation and test examples.
-
-### Success Metrics
 
 | Metric | Target | Measurement Method |
 |--------|--------|-------------------|
@@ -40,90 +45,22 @@ NATSBridge is a cross-platform, bi-directional data bridge that enables seamless
 
 ---
 
-## User Stories
+## 2. Technical Boundaries
 
-### Core Functionality
+### 2.1 In Scope
 
-| Story | Priority | Acceptance Criteria |
+| Feature | Description |
-|-------|----------|---------------------|
+|---------|-------------|
-| **As a Julia developer**, I want to send text messages to JavaScript applications that lives on a server and also on a browser  | P1 | Text messages are serialized, encoded, and received correctly across platforms |
+| Cross-platform interoperability | Seamless data exchange between Julia, JavaScript, Python, Dart, and MicroPython |
-| **As a Python developer**, I want to send tabular data to Julia applications | P1 | DataFrame exchange works with both Arrow IPC and JSON formats |
+| Intelligent transport selection | Direct transport (<0.5MB) vs Link transport (≥0.5MB) based on payload size |
-| **As a JavaScript developer**, I want to send large files (>0.5MB) from JavaScript applications that lives on a server and also on a browser to other applications | P1 | Large files are automatically uploaded to file server and URLs are sent via NATS |
+| Unified API | Consistent `smartsend()` and `smartreceive()` functions across all platforms |
-| **As a MicroPython developer**, I want to send sensor data with minimal memory usage | P1 | Direct transport works for payloads <100KB on memory-constrained devices |
+| Multi-payload support | List of (dataname, data, type) tuples with appropriate handling |
+| File server integration | Plik one-shot upload and custom HTTP server support |
+| Reliability features | Exponential backoff retry and correlation ID propagation |
+| Message serialization | Converts data types to binary format (Base64, JSON, Arrow IPC) |
+| NATS communication | Publishing and subscription via NATS subjects |
 
-### Multi-Payload Support
+### 2.2 Out of Scope
-
-| Story | Priority | Acceptance Criteria |
-|-------|----------|---------------------|
-| **As a developer**, I want to send mixed-content messages (text + image + file) | P1 | NATSBridge accepts list of (dataname, data, type) tuples and handles each payload appropriately |
-| **As a developer**, I want to receive multi-payload messages | P1 | NATSBridge returns payloads as list of tuples with correct types preserved |
-
-### File Server Integration
-
-| Story | Priority | Acceptance Criteria |
-|-------|----------|---------------------|
-| **As a developer**, I want to use Plik as the file server | P2 | Plik one-shot upload mode is supported with upload ID and token handling |
-| **As a developer**, I want to use custom HTTP file servers | P2 | Handler function abstraction allows plugging in AWS S3 or custom implementations |
-
-### Reliability Features
-
-| Story | Priority | Acceptance Criteria |
-|-------|----------|---------------------|
-| **As a developer**, I want automatic retry on file server download failures | P1 | Exponential backoff with configurable retries (default: 5, base_delay: 100ms, max_delay: 5000ms) |
-| **As a developer**, I want message tracing across distributed systems | P1 | Correlation ID is propagated through all message processing steps |
-
----
-
-## Non-Functional Requirements
-
-### Performance Requirements
-
-| Requirement | Specification | Test Method |
-|-------------|---------------|-------------|
-| Message serialization overhead | <50ms for 10KB payload | Benchmark tests |
-| Message deserialization overhead | <50ms for 10KB payload | Benchmark tests |
-| NATS connection establishment | <100ms | Connection pool benchmarks |
-| File upload latency | <1s for 0.5MB file | Integration tests |
-| File download latency | <1s for 0.5MB file | Integration tests |
-
-### Scalability Requirements
-
-| Requirement | Specification |
-|-------------|---------------|
-| Concurrent connections | Support 100+ simultaneous NATS connections |
-| Message throughput | Handle 1000+ messages/second per instance |
-| File server scalability | Support horizontal scaling of file server backend |
-
-### Reliability Requirements
-
-| Requirement | Specification |
-|-------------|---------------|
-| Message delivery | At-least-once delivery semantics via NATS |
-| File server availability | Graceful degradation when file server is unavailable |
-| Connection recovery | Auto-reconnect on NATS connection failure |
-
-### Security Requirements
-
-| Requirement | Specification |
-|-------------|---------------|
-| Payload integrity | SHA-256 checksum support via metadata |
-| Transport security | TLS support for NATS connections |
-| File server security | Authentication token for file uploads |
-
-### Compatibility Requirements
-
-| Platform | Minimum Version | Notes |
-|----------|-----------------|-------|
-| Julia | 1.7+ | Arrow.jl required for arrowtable support |
-| Node.js | 16+ | nats.js required |
-| Python | 3.8+ | pyarrow required for arrowtable support |
-| MicroPython | 1.19+ | Limited to direct transport |
-
----
-
-## Out of Scope
-
-### Phase 1 (Current Implementation)
 
 | Feature | Reason |
 |---------|--------|
@@ -133,94 +70,173 @@ NATSBridge is a cross-platform, bi-directional data bridge that enables seamless
 | Persistent message queues | NATS request-reply pattern sufficient |
 | Advanced routing rules | Simple NATS subject matching sufficient |
 
-### Future Considerations
+### 2.3 Dependencies
 
-| Feature | Future Phase |
+| Platform | Package | Version |
-|---------|--------------|
+|----------|---------|---------|
-| JetStream streams and consumers | Phase 2 |
+| Julia | NATS.jl | Latest stable |
-| Message TTL and dead-letter queues | Phase 3 |
+| Julia | JSON.jl | Latest stable |
-| Message tracing with OpenTelemetry | Phase 3 |
+| Julia | Arrow.jl | Latest stable |
-| Rate limiting and quota management | Phase 4 |
+| Julia | HTTP.jl | Latest stable |
+| Julia | UUIDs.jl | Latest stable |
+| Node.js | nats | Latest stable |
+| Node.js | node-fetch | Latest stable |
+| Python | nats-py | Latest stable |
+| Python | aiohttp | Latest stable |
+| Python | pyarrow | Latest stable |
+| Browser | nats.ws | Latest stable |
+| Dart | nats | Latest stable |
+| Dart | http | Latest stable |
+| Dart | uuid | Latest stable |
+
+### 2.4 Platform Compatibility
+
+| Platform | Minimum Version | Notes |
+|----------|-----------------|-------|
+| Julia | 1.7+ | Arrow.jl required for arrowtable support |
+| Node.js | 16+ | nats.js required, Arrow IPC supported |
+| Python | 3.8+ | pyarrow required for arrowtable support |
+| Browser | Latest | No Arrow IPC (uses jsontable only) |
+| Dart | 2.17+ | Supports Desktop (Dart SDK), Flutter (Dart SDK), and Web (Dart SDK) |
+| MicroPython | 1.19+ | Limited to direct transport |
 
 ---
 
-## Boundary Definitions
+## 3. Functional Requirements (FR)
 
-### What NATSBridge Handles
+| ID | Requirement | Description |
-
+|----|-------------|-------------|
-| Function | Description |
+| **FR-001** | Cross-platform text messaging | System shall allow users to send text messages between Julia, JavaScript, Python, and MicroPython applications |
-|----------|-------------|
+| **FR-002** | Cross-platform tabular data | System shall support DataFrame exchange between Julia and Python applications using Arrow IPC format |
-| Message serialization | Converts data types to binary format |
+| **FR-003** | Large file handling | System shall automatically detect payloads ≥0.5MB and upload them to HTTP file server instead of sending via NATS |
-| Message encoding | Base64, JSON, Arrow IPC encoding |
+| **FR-004** | Direct transport for small payloads | System shall send payloads <0.5MB directly via NATS without file server upload |
-| Transport selection | Direct vs link based on size threshold |
+| **FR-005** | MicroPython support | System shall support payloads <100KB on MicroPython devices using direct transport |
-| NATS publishing | Publishes messages to NATS subjects |
+| **FR-006** | Multi-payload messages | System shall accept and process lists of (dataname, data, type) tuples |
-| NATS subscription | Receives and processes NATS messages |
+| **FR-007** | Payload type preservation | System shall preserve payload types when returning multi-payload messages |
-| File server upload | Uploads large payloads to HTTP server |
+| **FR-008** | Plik file server integration | System shall support Plik one-shot upload mode with upload ID and token handling |
-| File server download | Downloads payloads from HTTP server with retry |
+| **FR-009** | Custom file server support | System shall provide handler function abstraction for custom HTTP file server implementations |
-| Correlation ID generation | Creates and propagates UUIDs |
+| **FR-010** | Exponential backoff retry | System shall implement exponential backoff with configurable retries (default: 5, base_delay: 100ms, max_delay: 5000ms) for file server download failures |
-| Data deserialization | Converts binary format back to native types |
+| **FR-011** | Correlation ID propagation | System shall propagate correlation IDs through all message processing steps |
-
+| **FR-012** | Message serialization | System shall serialize data types using Base64, JSON, or Arrow IPC encoding |
-### What NATSBridge Does NOT Handle
+| **FR-013** | NATS publishing | System shall publish messages to NATS subjects |
-
+| **FR-014** | NATS subscription | System shall receive and process NATS messages |
-| Function | Handled By |
-|----------|------------|
-| NATS server management | External NATS deployment |
-| File server management | External HTTP server deployment |
-| Application business logic | Application code using NATSBridge |
-| Message encryption | Application layer |
-| Message compression | Application layer |
-| Authentication/Authorization | NATS server configuration |
 
 ---
 
-## Payload Type Requirements
+## 4. Non-Functional Requirements (NFRs)
 
-### Supported Payload Types
+### 4.1 Performance & Scalability
 
-| Type | Julia | JavaScript | Python | MicroPython | Description |
+| ID | Requirement | Specification | Test Method |
-|------|-------|------------|--------|-------------|-------------|
+|----|-------------|---------------|-------------|
-| `text` | `String` | `string` | `str` | `str` | Plain text strings |
+| **NFR-101** | Message serialization overhead | <50ms for 10KB payload | Benchmark tests |
-| `dictionary` | `Dict`, `NamedTuple` | `Object`, `Array` | `dict`, `list` | `dict` | JSON-serializable data |
+| **NFR-102** | Message deserialization overhead | <50ms for 10KB payload | Benchmark tests |
-| `arrowtable` | `DataFrame`, `Arrow.Table` | `Array<Object>` | `pandas.DataFrame` | ❌ | Tabular data (Arrow IPC) |
+| **NFR-103** | NATS connection establishment | <100ms | Connection pool benchmarks |
-| `jsontable` | `Vector{NamedTuple}` | `Array<Object>` | `list[dict]` | ⚠️ | Tabular data (JSON) |
+| **NFR-104** | File upload latency | <1s for 0.5MB file | Integration tests |
-| `image` | `Vector{UInt8}` | `Uint8Array`, `Buffer` | `bytes` | `bytearray` | Image binary data |
+| **NFR-105** | File download latency | <1s for 0.5MB file | Integration tests |
-| `audio` | `Vector{UInt8}` | `Uint8Array`, `Buffer` | `bytes` | `bytearray` | Audio binary data |
+| **NFR-106** | Concurrent connections | Support 100+ simultaneous NATS connections | Scale testing |
-| `video` | `Vector{UInt8}` | `Uint8Array`, `Buffer` | `bytes` | `bytearray` | Video binary data |
+| **NFR-107** | Message throughput | Handle 1000+ messages/second per instance | Load testing |
-| `binary` | `Vector{UInt8}`, `IOBuffer` | `Uint8Array`, `Buffer` | `bytes`, `bytearray` | `bytearray` | Generic binary data |
+| **NFR-108** | File server scalability | Support horizontal scaling of file server backend | Architecture review |
 
-### Encoding Requirements
+### 4.2 Availability & Reliability
+
+| ID | Requirement | Specification |
+|----|-------------|---------------|
+| **NFR-201** | Message delivery | At-least-once delivery semantics via NATS |
+| **NFR-202** | File server availability | Graceful degradation when file server is unavailable |
+| **NFR-203** | Connection recovery | Auto-reconnect on NATS connection failure |
+
+### 4.3 Privacy & Security
+
+| ID | Requirement | Specification |
+|----|-------------|---------------|
+| **NFR-301** | Payload integrity | SHA-256 checksum support via metadata |
+| **NFR-302** | Transport security | TLS support for NATS connections |
+| **NFR-303** | File server security | Authentication token for file uploads |
+
+### 4.4 Observability & Telemetry
+
+| ID | Requirement | Specification |
+|----|-------------|---------------|
+| **NFR-401** | Required logs | `correlation_id`, `msg_id`, `timestamp`, `sender_name`, `receiver_name`, `payload_type`, `transport` |
+| **NFR-402** | Critical metrics | `messages_sent_total`, `messages_received_total`, `file_upload_duration_seconds`, `file_download_duration_seconds`, `retry_attempts_total` |
+| **NFR-403** | Tracing | Correlation ID propagation for request tracing |
+| **NFR-404** | Alerting | `download_retry_exceeded` triggers alert when max retries exceeded |
+| **NFR-405** | Retention | Logs: 30 days, Metrics: 1 year |
+
+---
+
+## 5. Acceptance Conditions
+
+| Condition | Description |
+|-----------|-------------|
+| **AC-001** | All functional requirements FR-001 through FR-014 are implemented and tested |
+| **AC-002** | All non-functional requirements NFR-101 through NFR-405 meet specified targets |
+| **AC-003** | Cross-platform text message test passes (Julia ↔ JavaScript ↔ Python) |
+| **AC-004** | Cross-platform tabular data test passes with Arrow IPC round-trip (Desktop) |
+| **AC-005** | Cross-platform tabular data test passes with JSON table round-trip (Browser) |
+| **AC-006** | Large file transfer test passes with file server upload/download |
+| **AC-007** | Multi-payload mixed content test passes with all payload types in one message |
+| **AC-008** | CI validation gates block PRs on specification violations |
+| **AC-009** | Unit test coverage exceeds 80% |
+| **AC-010** | Documentation is complete and includes walkthroughs, architecture, and runbook |
+
+---
+
+## 6. Payload Type Requirements
+
+### 6.1 Supported Payload Types
+
+| Type | Julia | JavaScript | Python | Dart | MicroPython | Description |
+|------|-------|------------|--------|------|-------------|-------------|
+| `text` | `String` | `string` | `str` | `String` | `str` | Plain text strings |
+| `dictionary` | `Dict`, `NamedTuple` | `Object`, `Array` | `dict`, `list` | `Map` | `dict` | JSON-serializable data |
+| `arrowtable` | `DataFrame`, `Arrow.Table` | ❌ (Browser), ✅ (Node.js) | `pandas.DataFrame` | `List<Map>` (Desktop), `List<dynamic>` (Flutter) | ❌ | Tabular data (Arrow IPC) |
+| `jsontable` | `Vector{NamedTuple}` | `Array<Object>` | `list[dict]` | `List<Map>` | ⚠️ | Tabular data (JSON) - **Only table type in Browser** |
+| `image` | `Vector{UInt8}` | `Uint8Array`, `Buffer` | `bytes` | `Uint8List` | `bytearray` | Image binary data |
+| `audio` | `Vector{UInt8}` | `Uint8Array`, `Buffer` | `bytes` | `Uint8List` | `bytearray` | Audio binary data |
+| `video` | `Vector{UInt8}` | `Uint8Array`, `Buffer` | `bytes` | `Uint8List` | `bytearray` | Video binary data |
+| `binary` | `Vector{UInt8}`, `IOBuffer` | `Uint8Array`, `Buffer` | `bytes`, `bytearray` | `Uint8List` | `bytearray` | Generic binary data |
+
+### 6.2 Encoding Requirements
 
 | Payload Type | Encoding Method | Notes |
 |--------------|-----------------|-------|
 | `text` | UTF-8 → Base64 | Text must be String type |
 | `dictionary` | JSON → Base64 | JSON.jl for Julia |
-| `arrowtable` | Arrow IPC → Base64 | Requires Arrow.jl/pyarrow |
+| `arrowtable` | Arrow IPC → Base64 | Requires Arrow.jl/pyarrow (Desktop only) |
-| `jsontable` | JSON → Base64 | Human-readable format |
+| `jsontable` | JSON → Base64 | Human-readable format - **Browser uses this only** |
 | `image`/`audio`/`video`/`binary` | Direct → Base64 | Binary data preserved |
 
 ---
 
-## Size Threshold Requirements
+## 7. Size Threshold Requirements
 
-### Direct Transport Threshold
+### 7.1 Direct Transport Threshold
 
 | Platform | Threshold | Notes |
 |----------|-----------|-------|
-| Desktop (Julia/JS/Python) | 0.5MB | Default size threshold |
+| Desktop (Julia/JS/Python/Dart) | 0.5MB | Default size threshold |
+| Dart Desktop | 0.5MB | Default size threshold |
+| Dart Flutter | 0.5MB | Default size threshold |
+| Dart Web | 0.5MB | Default size threshold |
 | MicroPython | 100KB | Lower threshold for memory constraints |
 
-### Maximum Payload Size
+### 7.2 Maximum Payload Size
 
 | Platform | Maximum | Notes |
 |----------|---------|-------|
 | Desktop | Unlimited | Limited by NATS server configuration |
+| Dart Desktop | Unlimited | Limited by NATS server configuration |
+| Dart Flutter | Unlimited | Limited by NATS server configuration |
+| Dart Web | Unlimited | Limited by NATS server configuration |
 | MicroPython | 50KB | Hard limit due to 256KB-1MB memory |
 
 ---
 
-## Message Envelope Requirements
+## 8. Message Envelope Requirements
 
-### Required Fields
+### 8.1 Required Fields
 
 | Field | Type | Purpose |
 |-------|------|---------|
@@ -239,7 +255,7 @@ NATSBridge is a cross-platform, bi-directional data bridge that enables seamless
 | `metadata` | Dict | Message-level metadata |
 | `payloads` | Array | List of payload objects |
 
-### Payload Fields
+### 8.2 Payload Fields
 
 | Field | Type | Purpose |
 |-------|------|---------|
@@ -254,9 +270,9 @@ NATSBridge is a cross-platform, bi-directional data bridge that enables seamless
 
 ---
 
-## Error Handling Requirements
+## 9. Error Handling Requirements
 
-### Error Codes
+### 9.1 Error Codes
 
 | Error | Condition | Response |
 |-------|-----------|----------|
@@ -266,7 +282,7 @@ NATSBridge is a cross-platform, bi-directional data bridge that enables seamless
 | `Unknown transport` | Invalid transport type | Throw error |
 | `NATS connection failed` | NATS unavailable | Throw error |
 
-### Exception Handling
+### 9.2 Exception Handling
 
 | Scenario | Handler |
 |----------|---------|
@@ -277,9 +293,9 @@ NATSBridge is a cross-platform, bi-directional data bridge that enables seamless
 
 ---
 
-## Testing Requirements
+## 10. Testing Requirements
 
-### Unit Tests
+### 10.1 Unit Tests
 
 | Test Category | Coverage | Files |
 |---------------|----------|-------|
@@ -289,20 +305,21 @@ NATSBridge is a cross-platform, bi-directional data bridge that enables seamless
 | File server upload | Plik integration | Platform-specific |
 | File server download | Exponential backoff | Platform-specific |
 
-### Integration Tests
+### 10.2 Integration Tests
 
 | Test Scenario | Success Criteria |
 |-------------|-----------------|
 | Cross-platform text message | Julia ↔ JavaScript ↔ Python |
-| Cross-platform tabular data | Arrow IPC round-trip |
+| Cross-platform tabular data (Desktop) | Arrow IPC round-trip |
+| Cross-platform tabular data (Browser) | JSON table round-trip |
 | Large file transfer | File server upload/download |
 | Multi-payload mixed content | All payload types in one message |
 
 ---
 
-## API Contract
+## 11. API Contract
 
-### smartsend Signature
+### 11.1 smartsend Signature
 
 ```julia
 function smartsend(
@@ -326,7 +343,7 @@ function smartsend(
 )::Tuple{msg_envelope_v1, String}
 ```
 
-### smartreceive Signature
+### 11.2 smartreceive Signature
 
 ```julia
 function smartreceive(
@@ -340,44 +357,18 @@ function smartreceive(
 
 ---
 
-## Dependencies
+## 12. Deployment Requirements
 
-### Required Dependencies
+### 12.1 Minimum Infrastructure
-
-| Platform | Package | Version |
-|----------|---------|---------|
-| Julia | NATS.jl | Latest stable |
-| Julia | JSON.jl | Latest stable |
-| Julia | Arrow.jl | Latest stable |
-| Julia | HTTP.jl | Latest stable |
-| Julia | UUIDs.jl | Latest stable |
-| Node.js | nats | Latest stable |
-| Node.js | node-fetch | Latest stable |
-| Python | nats-py | Latest stable |
-| Python | aiohttp | Latest stable |
-| Python | pyarrow | Latest stable |
-
-### Optional Dependencies
-
-| Platform | Package | Use Case |
-|----------|---------|----------|
-| Julia | DataFrames.jl | DataFrame support for arrowtable |
-| Python | pandas | DataFrame support for arrowtable |
-
----
-
-## Deployment Requirements
-
-### Minimum Infrastructure
 
 | Component | Minimum | Notes |
 |-----------|---------|-------|
 | NATS Server | 1 instance | Single node for development |
 | File Server | 1 instance | HTTP server for large payloads |
-| Client Memory | 50MB | Desktop platforms |
+| Client Memory | 50MB | Desktop platforms (Julia/JS/Python/Dart) |
 | Client Memory | 256KB | MicroPython devices |
 
-### Environment Variables
+### 12.2 Environment Variables
 
 | Variable | Default | Description |
 |----------|---------|-------------|
@@ -387,34 +378,42 @@ function smartreceive(
 
 ---
 
-## Versioning
+## 13. Versioning
 
-### Current Version
+### 13.1 Current Version
 
 - **Major**: 1 (Breaking changes require major version bump)
 - **Minor**: 0 (Feature additions)
 - **Patch**: 0 (Bug fixes)
 
-### Version Compatibility
+### 13.2 Version Compatibility
 
 | Version | Supported Platforms |
 |---------|---------------------|
-| v1.0.x | Julia 1.7+, Node.js 16+, Python 3.8+, MicroPython 1.19+ |
+| v1.0.x | Julia 1.7+, Node.js 16+, Python 3.8+, Dart 2.17+, Browser (latest), MicroPython 1.19+ |
 
 ---
 
-## Change Log
+## 14. Change Log
 
 | Date | Version | Changes |
 |------|---------|---------|
-| 2026-03-13 | 1.0.0 | Initial requirements document |
+| 2026-03-23 | 1.0.0 | Updated to ASG Framework requirements structure |
 
 ---
 
-## References
+## 15. References
 
-- [`src/NATSBridge.jl`](../src/NATSBridge.jl) - Ground truth implementation
+- [`src/NATSBridge.jl`](../src/NATSBridge.jl) - Ground truth implementation (Julia)
+- [`src/natsbridge_ssr.js`](../src/natsbridge_ssr.js) - Server-side JavaScript implementation
+- [`src/natsbridge_csr.js`](../src/natsbridge_csr.js) - Client-side JavaScript implementation
+- [`src/natsbridge.py`](../src/natsbridge.py) - Python implementation
+- [`src/natsbridge.dart`](../src/natsbridge.dart) - Dart implementation
+- [`src/natsbridge_mpy.py`](../src/natsbridge_mpy.py) - MicroPython implementation
 - [`README.md`](../README.md) - Project overview
+- [`docs/specification.md`](./specification.md) - Technical specification
+- [`docs/ui-specification.md`](./ui-specification.md) - UI specification
+- [`docs/walkthrough.md`](./walkthrough.md) - End-to-end walkthrough
 - [`docs/architecture.md`](./architecture.md) - Architecture documentation
-- [`docs/implementation.md`](./implementation.md) - Implementation details
+- [`docs/validation.md`](./validation.md) - Validation and CI/CD
-- [`docs/walkthrough.md`](./walkthrough.md) - Usage examples
+- [`docs/runbook.md`](./runbook.md) - Operational runbook

docs/specification.md

@@ -1,16 +1,16 @@
 # Specification: NATSBridge
 
-**Version**: 1.0.0  
+**Version**: 1.1.0  
-**Date**: 2026-03-13  
+**Date**: 2026-03-23  
 **Status**: Active  
 **Ground Truth**: [`src/NATSBridge.jl`](../src/NATSBridge.jl)  
 **Specification Format**: JSON Schema + AsyncAPI
 
 ---
 
-## Executive Summary
+## 1. Technical Contract Overview
 
-This document defines the **technical contract** for NATSBridge - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, and **MicroPython** applications using NATS as the message bus.
+This document defines the **technical contract** for NATSBridge - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, and **MicroPython** applications using NATS as the message bus.
 
 This specification serves as the single source of truth for:
 - **Inputs**: What data structures are accepted by `smartsend()`
@@ -18,8 +18,33 @@ This specification serves as the single source of truth for:
 - **Data Shapes**: Exact field names, types, and constraints
 - **Error Codes**: Standardized error responses for failure scenarios
 
+### 1.1 Requirements Traceability
+
+| Specification Section | Requirement ID(s) | Description |
+|----------------------|-------------------|-------------|
+| Section 2 (Message Envelope) | FR-012, FR-013, NFR-101, NFR-102 | Message envelope structure and validation |
+| Section 3 (Payload Schema) | FR-001, FR-002, FR-003, FR-004, NFR-101, NFR-102 | Payload structure and field definitions |
+| Section 4 (Payload Format) | FR-006, FR-007 | Tuple format for smartsend() |
+| Section 5 (Enumerations) | FR-003, FR-004, FR-006, NFR-101 | Enumerations for transport and encoding |
+| Section 6 (Transport Protocols) | FR-003, FR-004, NFR-104, NFR-105 | Direct and link transport protocols |
+| Section 7 (Size Thresholds) | FR-004, FR-005, NFR-104, NFR-105 | Size thresholds for transport selection |
+| Section 8 (NATS Subject Convention) | FR-013, FR-014 | NATS subject naming patterns |
+| Section 9 (Error Handling) | FR-010, FR-011, NFR-201, NFR-202, NFR-203 | Error codes and exception handling |
+| Section 10 (Serialization Rules) | FR-001, FR-002, FR-003, FR-012, NFR-101, NFR-102 | Serialization and encoding rules |
+| Section 11 (API Contract) | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-008, FR-009, FR-010, FR-011, FR-012, FR-013, FR-014 | Function signatures for all platforms |
+| Section 12 (File Server Interface) | FR-008, FR-009, FR-010 | Upload and download handler contracts |
+| Section 13 (Platform-Specific Constraints) | FR-005, FR-006, NFR-106, NFR-107 | Platform-specific feature support |
+| Section 14 (Implementation Files) | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007 | Implementation file mapping |
+| Section 15 (Message Flow) | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-008, FR-009, FR-010, FR-011, FR-012, FR-013, FR-014 | Mermaid diagrams for send/receive flows |
+| Section 16 (Validation Rules) | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-008, FR-009, FR-010, FR-011, FR-012, FR-013, FR-014 | Envelope and payload validation rules |
+| Section 17 (Test Contracts) | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-008, FR-009, FR-010, FR-011, FR-012, FR-013, FR-014 | Unit and integration test scenarios |
+| Section 18 (Dependencies) | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-008, FR-009, FR-010, FR-011, FR-012, FR-013, FR-014 | Platform-specific dependencies |
+| Section 19 (Change Log) | N/A | Version history and changes |
+
 ---
 
+## 2. Message Envelope Schema
+
 ## Specification Versioning
 
 | Component | Version | Notes |
@@ -65,22 +90,22 @@ This specification serves as the single source of truth for:
 
 ### Field Definitions
 
-| Field | Type | Required | Validation | Description |
+| Field | Type | Required | Validation | Description | Requirement ID |
-|-------|------|----------|------------|-------------|
+|-------|------|----------|------------|-------------|----------------|
-| `correlation_id` | `string` | Yes | UUID v4 format | Track message flow across distributed systems |
+| `correlation_id` | `string` | Yes | UUID v4 format | Track message flow across distributed systems | FR-011, NFR-401 |
-| `msg_id` | `string` | Yes | UUID v4 format | Unique identifier for this specific message |
+| `msg_id` | `string` | Yes | UUID v4 format | Unique identifier for this specific message | FR-012, NFR-401 |
-| `timestamp` | `string` | Yes | ISO 8601 UTC | Message publication timestamp (e.g., `2026-03-13T07:02:50.443Z`) |
+| `timestamp` | `string` | Yes | ISO 8601 UTC | Message publication timestamp | FR-012, NFR-401 |
-| `send_to` | `string` | Yes | Non-empty string | NATS subject/topic to publish the message to |
+| `send_to` | `string` | Yes | Non-empty string | NATS subject/topic to publish the message to | FR-013 |
-| `msg_purpose` | `string` | Yes | Enum | Purpose of the message (see `msg_purpose` enum) |
+| `msg_purpose` | `string` | Yes | Enum | Purpose of the message | FR-013 |
-| `sender_name` | `string` | Yes | Non-empty string | Name of the sender application |
+| `sender_name` | `string` | Yes | Non-empty string | Name of the sender application | FR-013 |
-| `sender_id` | `string` | Yes | UUID v4 format | Unique identifier for the sender |
+| `sender_id` | `string` | Yes | UUID v4 format | Unique identifier for the sender | FR-013 |
-| `receiver_name` | `string` | Yes | Any string | Name of the receiver (empty = broadcast) |
+| `receiver_name` | `string` | Yes | Any string | Name of the receiver (empty = broadcast) | FR-013 |
-| `receiver_id` | `string` | Yes | Any string | UUID of the receiver (empty = broadcast) |
+| `receiver_id` | `string` | Yes | Any string | UUID of the receiver (empty = broadcast) | FR-013 |
-| `reply_to` | `string` | Yes | Any string | Topic where receiver should reply (empty = no reply expected) |
+| `reply_to` | `string` | Yes | Any string | Topic where receiver should reply | FR-013 |
-| `reply_to_msg_id` | `string` | Yes | Any string | Message ID this message is replying to |
+| `reply_to_msg_id` | `string` | Yes | Any string | Message ID this message is replying to | FR-013 |
-| `broker_url` | `string` | Yes | Valid URL | NATS broker URL |
+| `broker_url` | `string` | Yes | Valid URL | NATS broker URL | FR-013 |
-| `metadata` | `object` | No | Any JSON object | Message-level metadata |
+| `metadata` | `object` | No | Any JSON object | Message-level metadata | NFR-401 |
-| `payloads` | `array` | Yes | Non-empty array | List of payload objects |
+| `payloads` | `array` | Yes | Non-empty array | List of payload objects | FR-012, FR-013 |
 
 ---
 
@@ -103,16 +128,16 @@ This specification serves as the single source of truth for:
 
 ### Payload Field Definitions
 
-| Field | Type | Required | Validation | Description |
+| Field | Type | Required | Validation | Description | Requirement ID |
-|-------|------|----------|------------|-------------|
+|-------|------|----------|------------|-------------|----------------|
-| `id` | `string` | Yes | UUID v4 format | Unique identifier for this payload |
+| `id` | `string` | Yes | UUID v4 format | Unique identifier for this payload | FR-012 |
-| `dataname` | `string` | Yes | Non-empty string | Name of the payload (e.g., `login_image`, `user_data`) |
+| `dataname` | `string` | Yes | Non-empty string | Name of the payload (e.g., `login_image`, `user_data`) | FR-001, FR-002, FR-003 |
-| `payload_type` | `string` | Yes | Enum | Type of payload (see `payload_type` enum) |
+| `payload_type` | `string` | Yes | Enum | Type of payload (see `payload_type` enum) | FR-001, FR-002, FR-003, FR-006 |
-| `transport` | `string` | Yes | Enum | Transport method: `direct` or `link` |
+| `transport` | `string` | Yes | Enum | Transport method: `direct` or `link` | FR-003, FR-004, NFR-104, NFR-105 |
-| `encoding` | `string` | Yes | Enum | Encoding method (see `encoding` enum) |
+| `encoding` | `string` | Yes | Enum | Encoding method (see `encoding` enum) | FR-001, FR-002, FR-003, FR-012 |
-| `size` | `integer` | Yes | Positive integer | Size of the payload in bytes |
+| `size` | `integer` | Yes | Positive integer | Size of the payload in bytes | FR-003, FR-004, NFR-104, NFR-105 |
-| `data` | `string` or `URL` | Yes | Base64 string or URL | Payload data (base64 for direct, URL for link) |
+| `data` | `string` or `URL` | Yes | Base64 string or URL | Payload data (base64 for direct, URL for link) | FR-003, FR-004, FR-008, FR-009, FR-010 |
-| `metadata` | `object` | No | Any JSON object | Payload-level metadata |
+| `metadata` | `object` | No | Any JSON object | Payload-level metadata | NFR-401 |
 
 ---
 
@@ -176,6 +201,7 @@ await smartsend("/agent/v1/process", data)
 | All | `String` | `"text"` |
 | All | `Dict`/`Object` | `"dictionary"` |
 | Desktop | `DataFrame` | `"arrowtable"` or `"jsontable"` |
+| Browser | `Array` of objects | `"jsontable"` (only table type) |
 | All | `Array` of objects | `"jsontable"` |
 | All | `Uint8Array`/`Buffer`/`bytes` | `"binary"` |
 | Desktop | `Arrow.Table` | `"arrowtable"` |
@@ -203,8 +229,8 @@ await smartsend("/agent/v1/process", data)
 |-------|-------------|---------------------|------------------|
 | `text` | Plain text string | All | `base64` |
 | `dictionary` | JSON object/dictionary | All | `base64`, `json` |
-| `arrowtable` | Apache Arrow IPC table | Desktop (Julia/JS/Python) | `base64`, `arrow-ipc` |
+| `arrowtable` | Apache Arrow IPC table | Desktop (Julia/Python/Node.js/Dart) | `base64`, `arrow-ipc` |
-| `jsontable` | JSON array of objects | All | `base64`, `json` |
+| `jsontable` | JSON array of objects | All (including Browser/Dart Web) | `base64`, `json` |
 | `image` | Binary image data | All | `base64` |
 | `audio` | Binary audio data | All | `base64` |
 | `video` | Binary video data | All | `base64` |
@@ -324,25 +350,25 @@ When `transport = "link"`, the `data` field contains a URL pointing to the uploa
 
 ### Error Codes
 
-| Code | HTTP Status | Description | Recovery |
+| Code | HTTP Status | Description | Recovery | Requirement ID |
-|------|-------------|-------------|----------|
+|------|-------------|-------------|----------|----------------|
-| `INVALID_ENVELOPE` | 400 | Message envelope validation failed | Fix envelope structure |
+| `INVALID_ENVELOPE` | 400 | Message envelope validation failed | Fix envelope structure | FR-012, FR-013, FR-014 |
-| `INVALID_PAYLOAD_TYPE` | 400 | Unsupported payload type | Use supported payload_type |
+| `INVALID_PAYLOAD_TYPE` | 400 | Unsupported payload type | Use supported payload_type | FR-001, FR-002, FR-003, FR-006 |
-| `INVALID_TRANSPORT` | 400 | Unsupported transport type | Use `direct` or `link` |
+| `INVALID_TRANSPORT` | 400 | Unsupported transport type | Use `direct` or `link` | FR-003, FR-004, FR-006 |
-| `UPLOAD_FAILED` | 500 | File server upload failed | Retry or use direct transport |
+| `UPLOAD_FAILED` | 500 | File server upload failed | Retry or use direct transport | FR-008, FR-009 |
-| `DOWNLOAD_FAILED` | 503 | File server download failed | Retry with exponential backoff |
+| `DOWNLOAD_FAILED` | 503 | File server download failed | Retry with exponential backoff | FR-010, FR-011, NFR-201, NFR-202 |
-| `NATS_CONNECTION_FAILED` | 503 | NATS connection failed | Check NATS server availability |
+| `NATS_CONNECTION_FAILED` | 503 | NATS connection failed | Check NATS server availability | FR-013, FR-014, NFR-201, NFR-203 |
-| `DESERIALIZATION_ERROR` | 500 | Payload deserialization failed | Check payload_type matches data |
+| `DESERIALIZATION_ERROR` | 500 | Payload deserialization failed | Check payload_type matches data | FR-001, FR-002, FR-003, FR-012 |
-| `SIZE_EXCEEDED` | 413 | Payload exceeds maximum size | Split payload or use link transport |
+| `SIZE_EXCEEDED` | 413 | Payload exceeds maximum size | Split payload or use link transport | FR-003, FR-004, FR-005, NFR-104, NFR-105 |
 
 ### Exception Handling
 
-| Scenario | Handler | Retry Policy |
+| Scenario | Handler | Retry Policy | Requirement ID |
-|----------|---------|--------------|
+|----------|---------|--------------|----------------|
-| File server unavailable | Retry up to 5 times | Exponential backoff (100ms → 5000ms) |
+| File server unavailable | Retry up to 5 times | Exponential backoff (100ms → 5000ms) | FR-010, NFR-202 |
-| NATS publish failure | Connection auto-reconnect | TCP-level reconnection |
+| NATS publish failure | Connection auto-reconnect | TCP-level reconnection | FR-013, FR-014, NFR-201, NFR-203 |
-| Deserialization error | Log correlation ID and throw | No retry (data corruption) |
+| Deserialization error | Log correlation ID and throw | No retry (data corruption) | FR-001, FR-002, FR-003, FR-012, NFR-401 |
-| Memory overflow (MicroPython) | Reject payloads >50KB | No retry (client-side check) |
+| Memory overflow (MicroPython) | Reject payloads >50KB | No retry (client-side check) | FR-005, NFR-106 |
 
 ---
 
@@ -480,11 +506,38 @@ async function smartsend(
         reply_to?: string;
         reply_to_msg_id?: string;
         is_publish?: boolean;
-        nats_connection?: NATS.Connection;
+        nats_connection?: NATSClient | NATS.Connection;
         msg_id?: string;
         sender_id?: string;
     }
 ): Promise<[Object, string]>;
+
+// NATSClient class for connection management
+class NATSClient {
+    constructor(url: string, keepAlive?: boolean);
+    connect(): Promise<NATS.Connection>;
+    publish(subject: string, message: string, correlationId: string): Promise<void>;
+    close(): Promise<void>;
+    getConnection(): NATS.Connection | null;
+    isConnected(): boolean;
+}
+
+// NATSConnectionPool for managing multiple connections
+class NATSConnectionPool {
+    constructor(url: string, maxSize?: number);
+    acquire(): Promise<NATSClient>;
+    release(client: NATSClient): void;
+    closeAll(): Promise<void>;
+}
+
+// publishMessage function for manual publishing
+async function publishMessage(
+    brokerUrlOrClient: string | NATSClient | NATS.Connection,
+    subject: string,
+    message: string,
+    correlationId: string,
+    closeConnection?: boolean
+): Promise<void>;
 ```
 
 #### MicroPython
@@ -497,6 +550,58 @@ def smartsend(
 ) -> Tuple[Dict, str]:
 ```
 
+#### Dart (Desktop/Flutter)
+
+```dart
+Future<[Map<String, dynamic>, String]> smartsend(
+  String subject,
+  List<List<dynamic>> data, {
+  String brokerUrl = 'nats://localhost:4222',
+  String fileserverUrl = 'http://localhost:8080',
+  Function? fileserverUploadHandler,
+  int sizeThreshold = 500000,
+  String? correlationId,
+  String msgPurpose = 'chat',
+  String senderName = 'NATSBridge',
+  String receiverName = '',
+  String receiverId = '',
+  String replyTo = '',
+  String replyToMsgId = '',
+  bool isPublish = true,
+  dynamic natsConnection,
+  String? msgId,
+  String? senderId,
+}) async {
+  // Returns [envelope, jsonString]
+}
+```
+
+#### Dart Web
+
+```dart
+Future<[Map<String, dynamic>, String]> smartsend(
+  String subject,
+  List<List<dynamic>> data, {
+  String brokerUrl = 'nats://localhost:4222',
+  String fileserverUrl = 'http://localhost:8080',
+  Function? fileserverUploadHandler,
+  int sizeThreshold = 500000,
+  String? correlationId,
+  String msgPurpose = 'chat',
+  String senderName = 'NATSBridge',
+  String receiverName = '',
+  String receiverId = '',
+  String replyTo = '',
+  String replyToMsgId = '',
+  bool isPublish = true,
+  dynamic natsConnection,
+  String? msgId,
+  String? senderId,
+}) async {
+  // Returns [envelope, jsonString]
+}
+```
+
 ### `smartreceive` Function Signature
 
 #### Julia
@@ -557,6 +662,34 @@ async function smartreceive(
 def smartreceive(msg: Any, **kwargs) -> Dict[str, Any]:
 ```
 
+#### Dart (Desktop/Flutter)
+
+```dart
+Future<Map<String, dynamic>> smartreceive(
+  Map<String, dynamic> msg, {
+  Function? fileserverDownloadHandler,
+  int maxRetries = 5,
+  int baseDelay = 100,
+  int maxDelay = 5000,
+}) async {
+  // Returns envelope with processed payloads
+}
+```
+
+#### Dart Web
+
+```dart
+Future<Map<String, dynamic>> smartreceive(
+  Map<String, dynamic> msg, {
+  Function? fileserverDownloadHandler,
+  int maxRetries = 5,
+  int baseDelay = 100,
+  int maxDelay = 5000,
+}) async {
+  // Returns envelope with processed payloads
+}
+```
+
 ---
 
 ## File Server Interface
@@ -613,16 +746,56 @@ function fileserver_download_handler(
 
 ## Platform-Specific Constraints
 
-### Desktop (Julia/JS/Python)
+### Desktop (Julia/Python/Node.js/Dart)
 
 | Feature | Status | Notes |
 |---------|--------|-------|
-| Arrow IPC | ✅ Supported | Requires Arrow.jl/pyarrow |
+| Arrow IPC | ✅ Supported | Requires Arrow.jl/pyarrow/dart-arrow |
 | JSON table | ✅ Supported | Human-readable format |
 | File server upload | ✅ Supported | HTTP/HTTPS |
 | File server download | ✅ Supported | HTTP/HTTPS |
 | Size threshold | 500KB | Configurable |
 
+### Browser (JavaScript)
+
+| Feature | Status | Notes |
+|---------|--------|-------|
+| Arrow IPC | ❌ Not supported | Apache Arrow not browser-compatible |
+| JSON table | ✅ Supported | Only table type available in browser |
+| File server upload | ✅ Supported | HTTP/HTTPS |
+| File server download | ✅ Supported | HTTP/HTTPS |
+| Size threshold | 500KB | Configurable |
+
+### Dart Desktop (Dart SDK)
+
+| Feature | Status | Notes |
+|---------|--------|-------|
+| Arrow IPC | ✅ Supported | Requires dart-arrow package |
+| JSON table | ✅ Supported | Human-readable format |
+| File server upload | ✅ Supported | HTTP/HTTPS |
+| File server download | ✅ Supported | HTTP/HTTPS |
+| Size threshold | 500KB | Configurable |
+
+### Dart Flutter (Dart SDK)
+
+| Feature | Status | Notes |
+|---------|--------|-------|
+| Arrow IPC | ✅ Supported | Requires dart-arrow package |
+| JSON table | ✅ Supported | Human-readable format |
+| File server upload | ✅ Supported | HTTP/HTTPS |
+| File server download | ✅ Supported | HTTP/HTTPS |
+| Size threshold | 500KB | Configurable |
+
+### Dart Web (Dart SDK)
+
+| Feature | Status | Notes |
+|---------|--------|-------|
+| Arrow IPC | ❌ Not supported | Apache Arrow not browser-compatible |
+| JSON table | ✅ Supported | Only table type available in browser |
+| File server upload | ✅ Supported | HTTP/HTTPS |
+| File server download | ✅ Supported | HTTP/HTTPS |
+| Size threshold | 500KB | Configurable |
+
 ### MicroPython
 
 | Feature | Status | Notes |
@@ -636,6 +809,42 @@ function fileserver_download_handler(
 
 ---
 
+## Implementation Files
+
+| File | Platform | Features | Notes |
+|------|----------|----------|-------|
+| [`src/NATSBridge.jl`](../src/NATSBridge.jl) | Julia | Full feature set, Arrow IPC, multiple dispatch | Ground truth implementation |
+| [`src/natsbridge_ssr.js`](../src/natsbridge_ssr.js) | Node.js | Arrow IPC, async/await | Server-side JavaScript |
+| [`src/natsbridge_csr.js`](../src/natsbridge_csr.js) | Browser | JSON table only, WebSocket NATS | Client-side rendering |
+| [`src/natsbridge.py`](../src/natsbridge.py) | Python | Arrow IPC, async/await | Desktop Python |
+| [`src/natsbridge.dart`](../src/natsbridge.dart) | Dart | Full feature set, Arrow IPC, async/await | Desktop/Flutter/Web |
+| [`src/natsbridge_mpy.py`](../src/natsbridge_mpy.py) | MicroPython | Limited to direct transport | Memory-constrained |
+
+### Browser Implementation Notes
+
+The browser implementation ([`src/natsbridge_csr.js`](../src/natsbridge_csr.js)) has the following constraints:
+
+| Constraint | Reason | Workaround |
+|------------|--------|------------|
+| No Apache Arrow IPC | Browser-incompatible dependency | Use `jsontable` for tabular data |
+| WebSocket NATS only | Browser cannot use TCP directly | Use `ws://` or `wss://` broker URLs |
+| Fetch API for HTTP | Browser fetch() API only | Compatible with Plik and other HTTP servers |
+
+### Payload Type Availability by Platform
+
+| Payload Type | Julia | Node.js | Browser | Python | Dart | MicroPython |
+|--------------|-------|---------|---------|--------|------|-------------|
+| `text` | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `dictionary` | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `arrowtable` | ✅ | ✅ | ❌ | ✅ | ✅ | ❌ |
+| `jsontable` | ✅ | ✅ | ✅ | ✅ | ✅ | ⚠️ |
+| `image` | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `audio` | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `video` | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `binary` | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
+
+---
+
 ## Message Flow
 
 ### Sending Flow
@@ -686,23 +895,23 @@ flowchart TD
 
 ### Envelope Validation
 
-| Rule | Condition | Error Code |
+| Rule | Condition | Error Code | Requirement ID |
-|------|-----------|------------|
+|------|-----------|------------|----------------|
-| Required fields present | `correlation_id`, `msg_id`, `timestamp`, `send_to`, `payloads` | `INVALID_ENVELOPE` |
+| Required fields present | `correlation_id`, `msg_id`, `timestamp`, `send_to`, `payloads` | `INVALID_ENVELOPE` | FR-012, FR-013 |
-| Valid UUID format | `correlation_id`, `msg_id`, `sender_id`, `receiver_id` | `INVALID_ENVELOPE` |
+| Valid UUID format | `correlation_id`, `msg_id`, `sender_id`, `receiver_id` | `INVALID_ENVELOPE` | FR-011, FR-012, NFR-401 |
-| Valid timestamp format | ISO 8601 UTC | `INVALID_ENVELOPE` |
+| Valid timestamp format | ISO 8601 UTC | `INVALID_ENVELOPE` | FR-012, NFR-401 |
-| Non-empty payloads array | `length(payloads) > 0` | `INVALID_ENVELOPE` |
+| Non-empty payloads array | `length(payloads) > 0` | `INVALID_ENVELOPE` | FR-012, FR-013 |
 
 ### Payload Validation
 
-| Rule | Condition | Error Code |
+| Rule | Condition | Error Code | Requirement ID |
-|------|-----------|------------|
+|------|-----------|------------|----------------|
-| Valid payload_type | Must be in `payload_type` enum | `INVALID_PAYLOAD_TYPE` |
+| Valid payload_type | Must be in `payload_type` enum | `INVALID_PAYLOAD_TYPE` | FR-001, FR-002, FR-003, FR-006 |
-| Valid transport | Must be `direct` or `link` | `INVALID_TRANSPORT` |
+| Valid transport | Must be `direct` or `link` | `INVALID_TRANSPORT` | FR-003, FR-004, FR-006 |
-| Valid encoding | Must match payload_type and transport | `INVALID_TRANSPORT` |
+| Valid encoding | Must match payload_type and transport | `INVALID_TRANSPORT` | FR-001, FR-002, FR-003, FR-012 |
-| Positive size | `size > 0` | `INVALID_PAYLOAD` |
+| Positive size | `size > 0` | `INVALID_PAYLOAD` | FR-003, FR-004, NFR-104, NFR-105 |
-| Valid Base64 for direct | `data` matches Base64 pattern | `DESERIALIZATION_ERROR` |
+| Valid Base64 for direct | `data` matches Base64 pattern | `DESERIALIZATION_ERROR` | FR-001, FR-002, FR-003, FR-012 |
-| Valid URL for link | `data` matches HTTP(S) URL pattern | `DOWNLOAD_FAILED` |
+| Valid URL for link | `data` matches HTTP(S) URL pattern | `DOWNLOAD_FAILED` | FR-008, FR-009, FR-010 |
 
 ---
 
@@ -710,14 +919,14 @@ flowchart TD
 
 ### Unit Test Validation
 
-| Test | Input | Expected Output | Notes |
+| Test | Input | Expected Output | Notes | Requirement ID |
-|------|-------|-----------------|-------|
+|------|-------|-----------------|-------|----------------|
-| Text round-trip | `("msg", "Hello", "text")` | `("msg", "Hello", "text")` | String serialization |
+| Text round-trip | `("msg", "Hello", "text")` | `("msg", "Hello", "text")` | String serialization | FR-001, FR-012, NFR-101, NFR-102 |
-| Dictionary round-trip | `("data", {"key": "value"}, "dictionary")` | `("data", {"key": "value"}, "dictionary")` | JSON object round-trip |
+| Dictionary round-trip | `("data", {"key": "value"}, "dictionary")` | `("data", {"key": "value"}, "dictionary")` | JSON object round-trip | FR-002, FR-012, NFR-101, NFR-102 |
-| Arrow table round-trip | `("table", arrow_table_data, "arrowtable")` | `("table", arrow_table_data, "arrowtable")` | Arrow IPC round-trip |
+| Arrow table round-trip | `("table", arrow_table_data, "arrowtable")` | `("table", arrow_table_data, "arrowtable")` | Arrow IPC round-trip | FR-002, FR-012, NFR-101, NFR-102 |
-| JSON table round-trip | `("table", [{"a":1},{"b":2}], "jsontable")` | `("table", [{"a":1},{"b":2}], "jsontable")` | JSON array of objects |
+| JSON table round-trip | `("table", [{"a":1},{"b":2}], "jsontable")` | `("table", [{"a":1},{"b":2}], "jsontable")` | JSON array of objects | FR-001, FR-002, FR-006, FR-012 |
-| Mixed payloads | `[("msg", "Hello", "text"), ("imgname", bytes, "binary")]` | `[("msg", "Hello", "text"), ("imgname", bytes, "binary")]` | Multiple payload types |
+| Mixed payloads | `[("msg", "Hello", "text"), ("imgname", bytes, "binary")]` | `[("msg", "Hello", "text"), ("imgname", bytes, "binary")]` | Multiple payload types | FR-006, FR-007 |
-| Large payload | `("data", rand(10_000_000), "arrowtable")` | `("data", URL, "arrowtable")` with link transport | File server upload |
+| Large payload | `("data", rand(10_000_000), "arrowtable")` | `("data", URL, "arrowtable")` with link transport | File server upload | FR-003, FR-004, FR-008, FR-009, NFR-104, NFR-105 |
 
 **Platform-Specific Notes:**
 - **Julia**: Use `Dict`, `Vector{Dict}`, or convert `DataFrame` to dictionary for testing
@@ -727,24 +936,24 @@ flowchart TD
 
 ### Integration Test Scenarios
 
-| Scenario | Platforms | Payloads | Size Mix | Transport | Expected Result |
+| Scenario | Platforms | Payloads | Size Mix | Transport | Expected Result | Requirement ID |
-|----------|-----------|----------|----------|-----------|-----------------|
+|----------|-----------|----------|----------|-----------|-----------------|----------------|
-| Single text (small) | All | `text` | Small | direct | Round-trip successful |
+| Single text (small) | All | `text` | Small | direct | Round-trip successful | FR-001, FR-012, NFR-101, NFR-102 |
-| Single dictionary (small) | All | `dictionary` | Small | direct | Round-trip successful |
+| Single dictionary (small) | All | `dictionary` | Small | direct | Round-trip successful | FR-002, FR-012, NFR-101, NFR-102 |
-| Single arrow table (small) | Julia/JS/Python | `arrowtable` | Small | direct | Arrow IPC round-trip |
+| Single arrow table (small) | Julia/JS/Python | `arrowtable` | Small | direct | Arrow IPC round-trip | FR-002, FR-012, NFR-101, NFR-102 |
-| Single JSON table (small) | All | `jsontable` | Small | direct | Dictionary array round-trip |
+| Single JSON table (small) | All | `jsontable` | Small | direct | Dictionary array round-trip | FR-001, FR-002, FR-006, FR-012 |
-| Single image (small) | All | `image` | Small | direct | Binary round-trip |
+| Single image (small) | All | `image` | Small | direct | Binary round-trip | FR-001, FR-006, FR-012 |
-| Single audio (small) | All | `audio` | Small | direct | Binary round-trip |
+| Single audio (small) | All | `audio` | Small | direct | Binary round-trip | FR-001, FR-006, FR-012 |
-| Single video (small) | All | `video` | Small | direct | Binary round-trip |
+| Single video (small) | All | `video` | Small | direct | Binary round-trip | FR-001, FR-006, FR-012 |
-| Single binary (small) | All | `binary` | Small | direct | Binary round-trip |
+| Single binary (small) | All | `binary` | Small | direct | Binary round-trip | FR-001, FR-006, FR-012 |
-| Single text (large) | All | `text` | Large | link | File server upload/download |
+| Single text (large) | All | `text` | Large | link | File server upload/download | FR-003, FR-004, FR-008, FR-009, NFR-104, NFR-105 |
-| Single JSON table (large) | All | `jsontable` | Large | link | File server upload/download |
+| Single JSON table (large) | All | `jsontable` | Large | link | File server upload/download | FR-003, FR-004, FR-008, FR-009, NFR-104, NFR-105 |
-| Single image (large) | All | `image` | Large | link | File server upload/download |
+| Single image (large) | All | `image` | Large | link | File server upload/download | FR-003, FR-004, FR-008, FR-009, NFR-104, NFR-105 |
-| **Ultimate Test** | Julia/JS/Python | `text` (small) + `dictionary` (small) + `arrowtable` (small) + `jsontable` (small) + `image` (small) + `audio` (small) + `video` (small) + `binary` (small) + `text` (large) + `dictionary` (large) + `arrowtable` (large) + `jsontable` (large) + `image` (large) | Mixed | direct/link | All payloads preserved with correct transport |
+| **Ultimate Test** | Julia/JS/Python | `text` (small) + `dictionary` (small) + `arrowtable` (small) + `jsontable` (small) + `image` (small) + `audio` (small) + `video` (small) + `binary` (small) + `text` (large) + `dictionary` (large) + `arrowtable` (large) + `jsontable` (large) + `image` (large) | Mixed | direct/link | All payloads preserved with correct transport | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-008, FR-009, FR-010, FR-011, FR-012, FR-013, FR-014 |
-| **Ultimate Test** | MicroPython | `text` (small) + `dictionary` (small) + `text` (large) + `dictionary` (large) | Mixed | direct | Limited to text/dictionary with direct transport only |
+| **Ultimate Test** | MicroPython | `text` (small) + `dictionary` (small) + `text` (large) + `dictionary` (large) | Mixed | direct | Limited to text/dictionary with direct transport only | FR-005, FR-006, FR-012 |
-| Cross-platform JSON table | All | `jsontable` | Small | direct | Dictionary array round-trip |
+| Cross-platform JSON table | All | `jsontable` | Small | direct | Dictionary array round-trip | FR-001, FR-002, FR-006, FR-012 |
-| MicroPython ↔ Desktop | MicroPython ↔ Desktop | `text`/`dictionary` | Small | direct | Limited payload types |
+| MicroPython ↔ Desktop | MicroPython ↔ Desktop | `text`/`dictionary` | Small | direct | Limited payload types | FR-005, FR-006, FR-012 |
-| Desktop ↔ Desktop (all combos) | Julia↔JS↔Python | All types | Small/Large | direct/link | Full compatibility |
+| Desktop ↔ Desktop (all combos) | Julia↔JS↔Python | All types | Small/Large | direct/link | Full compatibility | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-012, FR-013, FR-014 |
 
 ---
 
@@ -759,11 +968,17 @@ flowchart TD
 | Julia | Arrow.jl | Latest | Arrow IPC support |
 | Julia | HTTP.jl | Latest | HTTP file server |
 | Julia | UUIDs.jl | Latest | UUID generation |
-| Node.js | nats | Latest | NATS client |
+| Node.js | nats | Latest | NATS client (TCP) |
 | Node.js | node-fetch | Latest | HTTP file server |
+| Browser | nats.ws | Latest | NATS client (WebSocket) |
+| Browser | nats | Latest | NATS client (for bundling) |
 | Python | nats-py | Latest | NATS client |
 | Python | aiohttp | Latest | HTTP file server |
 | Python | pyarrow | Latest | Arrow IPC support |
+| Dart | nats | Latest | NATS client |
+| Dart | http | Latest | HTTP file server |
+| Dart | uuid | Latest | UUID generation |
+| Dart | dart-arrow | Latest | Arrow IPC support (Desktop/Flutter) |
 | MicroPython | builtin | N/A | Limited implementation |
 
 ### Optional Dependencies
@@ -779,6 +994,11 @@ flowchart TD
 
 | Date | Version | Changes |
 |------|---------|---------|
+| 2026-03-15 | 1.1.0 | Browser connection management |
+| - | - | Added NATSClient class with keepAlive support |
+| - | - | Added NATSConnectionPool for connection reuse |
+| - | - | Added publishMessage function with closeConnection option |
+| - | - | Added nats.ws to browser dependencies |
 | 2026-03-13 | 1.0.0 | Initial specification |
 | - | - | Message envelope schema defined |
 | - | - | Payload schema with transport modes |
@@ -791,11 +1011,55 @@ flowchart TD
 
 ## References
 
-- [`docs/requirements.md`](./requirements.md) - Business requirements and user stories
+### 20.1 Documentation Artifacts
-- [`docs/architecture.md`](./architecture.md) - System architecture diagrams
+
-- [`docs/implementation.md`](./implementation.md) - Implementation details
+| Document | Purpose | Requirements Traceability |
-- [`src/NATSBridge.jl`](../src/NATSBridge.jl) - Ground truth implementation
+|----------|---------|--------------------------|
-- [`README.md`](../README.md) - Project overview
+| [`docs/requirements.md`](./requirements.md) | Business requirements and user stories | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`docs/specification.md`](./specification.md) | Technical contract for NATSBridge | This document |
+| [`docs/ui-specification.md`](./ui-specification.md) | UI specification for client applications | UI components for data entry and display |
+| [`docs/walkthrough.md`](./walkthrough.md) | End-to-end system flow | Traceability from user journey to technical implementation |
+| [`docs/architecture.md`](./architecture.md) | System architecture diagrams | Component interaction and data flow |
+| [`docs/validation.md`](./validation.md) | CI/CD validation rules | Contract testing and spec compliance |
+| [`docs/runbook.md`](./runbook.md) | Operational runbook | Deployment, scaling, and troubleshooting |
+
+### 20.2 Implementation Files
+
+| File | Platform | Features | Requirements Traceability |
+|------|----------|----------|--------------------------|
+| [`src/NATSBridge.jl`](../src/NATSBridge.jl) | Julia | Full feature set, Arrow IPC, multiple dispatch | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/natsbridge_ssr.js`](../src/natsbridge_ssr.js) | Node.js | Arrow IPC, async/await | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/natsbridge_csr.js`](../src/natsbridge_csr.js) | Browser | JSON table only, WebSocket NATS | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/natsbridge.py`](../src/natsbridge.py) | Python | Arrow IPC, async/await | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/natsbridge_mpy.py`](../src/natsbridge_mpy.py) | MicroPython | Limited to direct transport | FR-005, FR-006, FR-012 |
+
+### 20.3 External Dependencies
+
+| Platform | Package | Version | Purpose | Requirements Traceability |
+|----------|---------|---------|---------|--------------------------|
+| Julia | NATS.jl | Latest | NATS client | FR-013, FR-014, NFR-201 |
+| Julia | JSON.jl | Latest | JSON serialization | FR-012, NFR-101, NFR-102 |
+| Julia | Arrow.jl | Latest | Arrow IPC support | FR-002, FR-012 |
+| Julia | HTTP.jl | Latest | HTTP file server | FR-008, FR-009 |
+| Julia | UUIDs.jl | Latest | UUID generation | FR-011, NFR-401 |
+| Node.js | nats | Latest | NATS client (TCP) | FR-013, FR-014 |
+| Node.js | node-fetch | Latest | HTTP file server | FR-008, FR-009 |
+| Browser | nats.ws | Latest | NATS client (WebSocket) | FR-013, FR-014 |
+| Browser | nats | Latest | NATS client (for bundling) | FR-013, FR-014 |
+| Python | nats-py | Latest | NATS client | FR-013, FR-014 |
+| Python | aiohttp | Latest | HTTP file server | FR-008, FR-009 |
+| Python | pyarrow | Latest | Arrow IPC support | FR-002, FR-012 |
+| MicroPython | builtin | N/A | Limited implementation | FR-005, FR-006 |
+
+---
+
+## 21. Change Log
+
+| Date | Version | Changes | Requirement ID(s) |
+|------|---------|---------|-------------------|
+| 2026-03-23 | 1.1.0 | Updated to ASG Framework specification guidelines | All |
+| 2026-03-15 | 1.1.0 | Browser connection management | FR-001 through FR-014 |
+| 2026-03-13 | 1.0.0 | Initial specification | FR-001 through FR-014, NFR-101 through NFR-405 |
 
 ---
 

docs/tutorial.md

@@ -1,741 +0,0 @@
-# Cross-Platform NATSBridge Tutorial
-
-A step-by-step guide to get started with NATSBridge across **Julia**, **JavaScript**, and **Python/MicroPython**.
-
-## Table of Contents
-
-1. [Overview](#overview)
-2. [Prerequisites](#prerequisites)
-3. [Installation](#installation)
-4. [Quick Start](#quick-start)
-5. [Basic Examples](#basic-examples)
-6. [Advanced Usage](#advanced-usage)
-
----
-
-## Overview
-
-NATSBridge enables seamless communication across platforms through NATS, with automatic transport selection based on payload size:
-
-- **Direct Transport**: Payloads < 1MB are sent directly via NATS (Base64 encoded)
-- **Link Transport**: Payloads >= 1MB are uploaded to an HTTP file server and referenced via URL
-
-### Cross-Platform API Parity
-
-All three platforms use the same high-level API:
-
-```
-# Input format
-smartsend(subject, [(dataname, data, type), ...], options)
-
-# Output format
-(env, env_json_str) = smartsend(...)
-env = smartreceive(msg, options)
-```
-
-**Important Platform Differences:**
-
-1. **Encoding field:** Julia and JavaScript preserve the original serialization format in the encoding field (`"base64"`, `"json"`, or `"arrow-ipc"`), while Python and MicroPython always use `"base64"` for all direct transport payloads.
-
-2. **Async vs Sync:** JavaScript and Python desktop use async/await, while MicroPython uses synchronous API.
-
-### Supported Payload Types
-
-| Type | Julia | JavaScript | Python | MicroPython |
-|------|-------|------------|--------|-------------|
-| `text` | `String` | `string` | `str` | `str` |
-| `dictionary` | `Dict` | `Object` | `dict` | `dict` |
-| `arrowtable` | `DataFrame` | `Array<Object>` | `pandas.DataFrame` | ❌ |
-| `jsontable` | `Vector{NamedTuple}` | `Array<Object>` | `list[dict]` | ❌ |
-| `table` | ❌ | ❌ | `pandas.DataFrame` | ❌ |
-| `image` | `Vector{UInt8}` | `Uint8Array` | `bytes` | `bytearray` |
-| `audio` | `Vector{UInt8}` | `Uint8Array` | `bytes` | `bytearray` |
-| `video` | `Vector{UInt8}` | `Uint8Array` | `bytes` | `bytearray` |
-| `binary` | `Vector{UInt8}` | `Uint8Array` | `bytes` | `bytearray` |
-
-**Note on MicroPython:** MicroPython does not support table types (`arrowtable`, `jsontable`, or `table`) due to memory constraints. Use `dictionary` or `binary` instead.
-
----
-
-## Prerequisites
-
-Before you begin, ensure you have:
-
-1. **NATS Server** running (or accessible)
-2. **HTTP File Server** (optional, for large payloads > 1MB)
-3. **Platform-specific packages** installed
-
----
-
-## Installation
-
-### Julia
-
-```julia
-using Pkg
-Pkg.add("NATS")
-Pkg.add("Arrow")
-Pkg.add("JSON3")
-Pkg.add("HTTP")
-Pkg.add("UUIDs")
-Pkg.add("Dates")
-```
-
-### JavaScript (Node.js)
-
-```bash
-npm install nats uuid apache-arrow node-fetch
-```
-
-### JavaScript (Browser)
-
-```html
-<script src="https://unpkg.com/nats-js/dist/bundle/nats.min.js"></script>
-<script src="https://unpkg.com/apache-arrow/arrow.min.js"></script>
-```
-
-### Python (Desktop)
-
-```bash
-pip install nats-py aiohttp pyarrow pandas
-```
-
-### MicroPython
-
-Uses built-in modules: `network`, `socket`, `time`, `json`, `base64`
-
----
-
-## Quick Start
-
-### Step 1: Start NATS Server
-
-```bash
-docker run -p 4222:4222 nats:latest
-```
-
-### Step 2: Start HTTP File Server (Optional)
-
-```bash
-mkdir -p /tmp/fileserver
-python3 -m http.server 8080 --directory /tmp/fileserver
-```
-
-### Step 3: Send Your First Message
-
-#### Julia
-
-```julia
-using NATSBridge
-
-# Send a text message
-data = [("message", "Hello World", "text")]
-env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222")
-# env: msg_envelope_v1 struct with all metadata and payloads
-# env_json_str: JSON string representation of the envelope for publishing
-println("Message sent!")
-
-# Or use is_publish=false to get envelope and JSON without publishing
-env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222", is_publish=false)
-# env: msg_envelope_v1 struct
-# env_json_str: JSON string for publishing to NATS
-```
-
-#### JavaScript
-
-```javascript
-const NATSBridge = require('./src/natsbridge.js');
-
-// Send a text message
-const data = [["message", "Hello World", "text"]];
-const [env, env_json_str] = await NATSBridge.smartsend(
-    "/chat/room1",
-    data,
-    { broker_url: "nats://localhost:4222" }
-);
-// env: Object with all metadata and payloads
-// env_json_str: JSON string for publishing
-console.log("Message sent!");
-
-// Or use is_publish=false
-const [env, env_json_str] = await NATSBridge.smartsend(
-    "/chat/room1",
-    data,
-    { broker_url: "nats://localhost:4222", is_publish: false }
-);
-```
-
-#### Python
-
-```python
-from natsbridge import smartsend
-
-# Send a text message
-data = [("message", "Hello World", "text")]
-env, env_json_str = await smartsend(
-    "/chat/room1",
-    data,
-    broker_url="nats://localhost:4222"
-)
-# env: Dict with all metadata and payloads
-# env_json_str: JSON string for publishing
-print("Message sent!")
-
-# Or use is_publish=False
-env, env_json_str = await smartsend(
-    "/chat/room1",
-    data,
-    broker_url="nats://localhost:4222",
-    is_publish=False
-)
-# env: Dict with all metadata and payloads
-# env_json_str: JSON string for publishing to NATS
-```
-
-#### MicroPython
-
-```python
-from natsbridge_mpy import NATSBridge
-
-bridge = NATSBridge()
-
-# Send a text message (limited to small payloads)
-data = [("message", "Hello World", "text")]
-env, env_json_str = bridge.smartsend(
-    "/chat/room1",
-    data,
-    size_threshold=100000  # Lower threshold for MicroPython
-)
-print("Message sent!")
-```
-
-### Step 4: Receive Messages
-
-#### Julia
-
-```julia
-using NATSBridge
-
-# Receive and process message
-env = smartreceive(msg; fileserver_download_handler=_fetch_with_backoff)
-# Returns: ::JSON.Object{String, Any} with "payloads" field containing Vector{Tuple{String, Any, String}}
-# Access payloads: for (dataname, data, type) in env["payloads"]
-for (dataname, data, type) in env["payloads"]
-    println("Received $dataname: $data")
-end
-```
-
-#### JavaScript
-
-```javascript
-const NATSBridge = require('./src/natsbridge.js');
-
-// Receive and process message
-const env = await NATSBridge.smartreceive(msg, {
-    fileserver_download_handler: NATSBridge.fetchWithBackoff
-});
-// env.payloads = [[dataname, data, type], ...]
-for (const [dataname, data, type] of env.payloads) {
-    console.log(`Received ${dataname}:`, data);
-}
-```
-
-#### Python
-
-```python
-from natsbridge import smartreceive, fetch_with_backoff
-
-# Receive and process message
-env = await smartreceive(
-    msg,
-    fileserver_download_handler=fetch_with_backoff
-)
-# env["payloads"] = [(dataname, data, type), ...]
-for dataname, data, type_ in env["payloads"]:
-    print(f"Received {dataname}: {data}")
-```
-
----
-
-## Basic Examples
-
-### Example 1: Sending a Dictionary
-
-#### Julia
-
-```julia
-using NATSBridge
-
-config = Dict(
-    "wifi_ssid" => "MyNetwork",
-    "wifi_password" => "password123",
-    "update_interval" => 60
-)
-
-data = [("config", config, "dictionary")]
-env, env_json_str = smartsend("/device/config", data, broker_url="nats://localhost:4222")
-```
-
-#### JavaScript
-
-```javascript
-const NATSBridge = require('./src/natsbridge.js');
-
-const config = {
-    wifi_ssid: "MyNetwork",
-    wifi_password: "password123",
-    update_interval: 60
-};
-
-const data = [["config", config, "dictionary"]];
-const [env, env_json_str] = await NATSBridge.smartsend(
-    "/device/config",
-    data,
-    { broker_url: "nats://localhost:4222" }
-);
-```
-
-#### Python
-
-```python
-from natsbridge import smartsend
-
-config = {
-    "wifi_ssid": "MyNetwork",
-    "wifi_password": "password123",
-    "update_interval": 60
-}
-
-data = [("config", config, "dictionary")]
-env, env_json_str = await smartsend(
-    "/device/config",
-    data,
-    broker_url="nats://localhost:4222"
-)
-```
-
-#### MicroPython
-
-```python
-from natsbridge_mpy import NATSBridge
-
-bridge = NATSBridge()
-
-config = {
-    "wifi_ssid": "MyNetwork",
-    "wifi_password": "password123",
-    "update_interval": 60
-}
-
-data = [("config", config, "dictionary")]
-env, env_json_str = bridge.smartsend(
-    "/device/config",
-    data,
-    size_threshold=100000
-)
-```
-
-### Example 2: Sending Binary Data (Image)
-
-#### Julia
-
-```julia
-using NATSBridge
-
-# Read image file
-image_data = read("image.png")
-
-data = [("user_image", image_data, "binary")]
-env, env_json_str = smartsend("/chat/image", data, broker_url="nats://localhost:4222")
-```
-
-#### JavaScript
-
-```javascript
-const NATSBridge = require('./src/natsbridge.js');
-const fs = require('fs');
-
-// Read image file
-const image_data = fs.readFileSync('image.png');
-
-const data = [["user_image", image_data, "binary"]];
-const [env, env_json_str] = await NATSBridge.smartsend(
-    "/chat/image",
-    data,
-    { broker_url: "nats://localhost:4222" }
-);
-```
-
-#### Python
-
-```python
-from natsbridge import smartsend
-
-# Read image file
-with open("image.png", "rb") as f:
-    image_data = f.read()
-
-data = [("user_image", image_data, "binary")]
-env, env_json_str = await smartsend(
-    "/chat/image",
-    data,
-    broker_url="nats://localhost:4222"
-)
-```
-
-#### MicroPython
-
-```python
-from natsbridge_mpy import NATSBridge
-
-bridge = NATSBridge()
-
-# Read image file
-with open("image.png", "rb") as f:
-    image_data = f.read()
-
-data = [("user_image", image_data, "binary")]
-env, env_json_str = bridge.smartsend(
-    "/chat/image",
-    data,
-    size_threshold=100000
-)
-```
-
-### Example 3: Request-Response Pattern
-
-#### Julia (Requester)
-
-```julia
-using NATSBridge
-
-# Send command with reply-to
-data = [("command", Dict("action" => "read_sensor"), "dictionary")]
-env, env_json_str = smartsend(
-    "/device/command",
-    data,
-    broker_url="nats://localhost:4222",
-    reply_to="/device/response",
-    reply_to_msg_id="cmd-001"
-)
-```
-
-#### JavaScript (Requester)
-
-```javascript
-const NATSBridge = require('./src/natsbridge.js');
-
-// Send command with reply-to
-const data = [["command", { action: "read_sensor" }, "dictionary"]];
-const [env, env_json_str] = await NATSBridge.smartsend(
-    "/device/command",
-    data,
-    {
-        broker_url: "nats://localhost:4222",
-        reply_to: "/device/response",
-        reply_to_msg_id: "cmd-001"
-    }
-);
-```
-
-#### Python (Requester)
-
-```python
-from natsbridge import smartsend
-
-# Send command with reply-to
-data = [("command", {"action": "read_sensor"}, "dictionary")]
-env, env_json_str = await smartsend(
-    "/device/command",
-    data,
-    broker_url="nats://localhost:4222",
-    reply_to="/device/response",
-    reply_to_msg_id="cmd-001"
-)
-```
-
-#### Julia (Responder)
-
-```julia
-using NATSBridge, NATS
-
-const SUBJECT = "/device/command"
-const NATS_URL = "nats://localhost:4222"
-
-function test_responder()
-    conn = NATS.connect(NATS_URL)
-    NATS.subscribe(conn, SUBJECT) do msg
-        env = smartreceive(msg, fileserver_download_handler=_fetch_with_backoff)
-        
-        reply_to = env["reply_to"]
-        
-        for (dataname, data, type) in env["payloads"]
-            if dataname == "command" && data["action"] == "read_sensor"
-                response = Dict("sensor_id" => "sensor-001", "value" => 42.5)
-                if !isempty(reply_to)
-                    smartsend(reply_to, [("data", response, "dictionary")])
-                end
-            end
-        end
-    end
-    
-    sleep(120)
-    NATS.drain(conn)
-end
-
-test_responder()
-```
-
----
-
-## Advanced Usage
-
-### Example 4: Large Payloads (File Server)
-
-For payloads larger than 1MB, NATSBridge automatically uses the file server:
-
-#### Julia
-
-```julia
-using NATSBridge
-
-# Create large data (> 1MB)
-large_data = rand(UInt8, 2_000_000)
-
-env, env_json_str = smartsend(
-    "/data/large",
-    [("large_file", large_data, "binary")],
-    broker_url="nats://localhost:4222",
-    fileserver_url="http://localhost:8080"
-)
-
-println("File uploaded to: $(env.payloads[1].data)")
-# Note: For link transport, data field contains the URL string
-```
-
-#### JavaScript
-
-```javascript
-const NATSBridge = require('./src/natsbridge.js');
-
-// Create large data (> 1MB)
-const large_data = Buffer.alloc(2_000_000);
-for (let i = 0; i < large_data.length; i++) {
-    large_data[i] = Math.floor(Math.random() * 256);
-}
-
-const [env, env_json_str] = await NATSBridge.smartsend(
-    "/data/large",
-    [["large_file", large_data, "binary"]],
-    {
-        broker_url: "nats://localhost:4222",
-        fileserver_url: "http://localhost:8080"
-    }
-);
-
-console.log("File uploaded to:", env.payloads[0].data);
-// Note: For link transport, data field contains the URL string
-```
-
-#### Python
-
-```python
-from natsbridge import smartsend
-
-# Create large data (> 1MB)
-import os
-large_data = os.urandom(2_000_000)
-
-env, env_json_str = await smartsend(
-    "/data/large",
-    [("large_file", large_data, "binary")],
-    broker_url="nats://localhost:4222",
-    fileserver_url="http://localhost:8080"
-)
-
-print(f"File uploaded to: {env['payloads'][0]['data']}")
-# Note: For link transport, data field contains the URL string
-```
-
-#### MicroPython
-
-MicroPython enforces a hard limit of 50KB per payload:
-
-```python
-from natsbridge_mpy import NATSBridge
-
-bridge = NATSBridge()
-
-# MicroPython has a hard limit of 50KB per payload
-# Use streaming or chunking for larger data
-small_data = bytes(1000)  # 1KB
-
-data = [("small_file", small_data, "binary")]
-env, env_json_str = bridge.smartsend(
-    "/data/small",
-    data,
-    size_threshold=100000  # Enforced max: 50000 bytes
-)
-```
-
-### Example 5: Mixed Content (Chat with Text + Image)
-
-NATSBridge supports sending multiple payloads with different types in a single message:
-
-#### Julia
-
-```julia
-using NATSBridge
-
-image_data = read("avatar.png")
-
-data = [
-    ("message_text", "Hello with image!", "text"),
-    ("user_avatar", image_data, "image")
-]
-
-env, env_json_str = smartsend("/chat/mixed", data, broker_url="nats://localhost:4222")
-```
-
-#### JavaScript
-
-```javascript
-const NATSBridge = require('./src/natsbridge.js');
-const fs = require('fs');
-
-const image_data = fs.readFileSync('avatar.png');
-
-const data = [
-    ["message_text", "Hello with image!", "text"],
-    ["user_avatar", image_data, "image"]
-];
-
-const [env, env_json_str] = await NATSBridge.smartsend(
-    "/chat/mixed",
-    data,
-    { broker_url: "nats://localhost:4222" }
-);
-```
-
-#### Python
-
-```python
-from natsbridge import smartsend
-
-with open("avatar.png", "rb") as f:
-    image_data = f.read()
-
-data = [
-    ("message_text", "Hello with image!", "text"),
-    ("user_avatar", image_data, "image")
-]
-
-env, env_json_str = await smartsend(
-    "/chat/mixed",
-    data,
-    broker_url="nats://localhost:4222"
-)
-# env: Dict with all metadata and payloads
-```
-
-### Example 6: Table Data (Arrow IPC)
-
-For tabular data, NATSBridge uses Apache Arrow IPC format:
-
-#### Julia
-
-```julia
-using NATSBridge
-using DataFrames
-
-# Create DataFrame
-df = DataFrame(
-    id = [1, 2, 3],
-    name = ["Alice", "Bob", "Charlie"],
-    score = [95, 88, 92]
-)
-
-data = [("students", df, "arrowtable")]
-env, env_json_str = smartsend("/data/students", data, broker_url="nats://localhost:4222")
-```
-
-#### JavaScript
-
-```javascript
-const NATSBridge = require('./src/natsbridge.js');
-
-// Create table data (array of objects)
-const table_data = [
-    { id: 1, name: "Alice", score: 95 },
-    { id: 2, name: "Bob", score: 88 },
-    { id: 3, name: "Charlie", score: 92 }
-];
-
-const data = [["students", table_data, "arrowtable"]];
-const [env, env_json_str] = await NATSBridge.smartsend(
-    "/data/students",
-    data,
-    { broker_url: "nats://localhost:4222" }
-);
-```
-
-#### Python
-
-```python
-from natsbridge import smartsend
-import pandas as pd
-
-# Create DataFrame
-df = pd.DataFrame({
-    'id': [1, 2, 3],
-    'name': ['Alice', 'Bob', 'Charlie'],
-    'score': [95, 88, 92]
-})
-
-data = [("students", df, "table")]
-env, env_json_str = await smartsend(
-    "/data/students",
-    data,
-    broker_url="nats://localhost:4222"
-)
-```
-
-#### MicroPython
-
-MicroPython does not support table type due to memory constraints. Use dictionary or binary instead.
-
----
-
-## Next Steps
-
-1. **Explore the test directory** for more examples
-2. **Check the documentation** for advanced configuration options
-3. **Read the walkthrough** for building real-world applications
-
----
-
-## Troubleshooting
-
-### Connection Issues
-
-- Ensure NATS server is running: `docker ps | grep nats`
-- Check firewall settings
-- Verify NATS URL configuration
-
-### File Server Issues
-
-- Ensure file server is running and accessible
-- Check upload permissions
-- Verify file server URL configuration
-
-### Serialization Errors
-
-- Verify data type matches the specified type
-- Check that binary data is in the correct format
-- MicroPython: Ensure payload size < 50KB
-
----
-
-## License
-
-MIT

docs/walkthrough.md

@@ -1,23 +1,40 @@
 # Walkthrough: NATSBridge
 
 **Version**: 1.0.0  
-**Date**: 2026-03-13  
+**Date**: 2026-03-23  
 **Status**: Active  
 **Ground Truth**: [`src/NATSBridge.jl`](../src/NATSBridge.jl)
 
 ---
 
-## Executive Summary
+## 1. Executive Summary
 
-This document provides the **story of flow** for NATSBridge - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, and **MicroPython** applications using NATS as the message bus.
+This document provides the **end-to-end trace** for NATSBridge - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, and **MicroPython** applications using NATS as the message bus.
 
 This walkthrough serves as the primary onboarding guide for new developers and explains:
 - **User scenarios** - Real-world use cases from developer perspective
 - **Why steps are sequenced** - The rationale behind architectural decisions
 - **What could go wrong** - Common failure scenarios and recovery strategies
 
+### 1.1 Specification Traceability
+
+| Walkthrough Section | Specification Reference | Requirement ID(s) | Description |
+|---------------------|-------------------------|-------------------|-------------|
+| Section 2 (Big Picture) | specification.md:2, specification.md:15 | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-012, FR-013, FR-014 | End-to-end system flow diagrams |
+| Section 3 (Chat Scenario) | specification.md:2, specification.md:3, specification.md:5, specification.md:11 | FR-001, FR-006, FR-007, FR-012, FR-013, FR-014 | Chat webapp ↔ Julia backend with mixed payloads |
+| Section 4 (Large File) | specification.md:6, specification.md:7 | FR-003, FR-004, FR-008, FR-009, FR-010, NFR-104, NFR-105 | Large file transfer with link transport |
+| Section 5 (Tabular Data) | specification.md:5, specification.md:10 | FR-002, FR-012, NFR-101, NFR-102 | Arrow IPC tabular data exchange |
+| Section 6 (MicroPython) | specification.md:13, specification.md:17 | FR-005, FR-006, FR-012, NFR-106 | Memory-constrained device communication |
+| Section 7 (Cross-Platform) | specification.md:3, specification.md:4, specification.md:5, specification.md:11 | FR-001, FR-002, FR-003, FR-004, FR-005, FR-006, FR-007, FR-012, FR-013, FR-014 | Multi-platform chat application |
+| Section 8 (Error Handling) | specification.md:9 | FR-008, FR-009, FR-010, NFR-201, NFR-202, NFR-203 | Common error scenarios and recovery |
+| Section 9 (Debugging) | specification.md:4, specification.md:11 | FR-011, NFR-401, NFR-403 | Correlation ID tracking |
+| Section 10 (Performance) | specification.md:7, specification.md:13 | NFR-101, NFR-102, NFR-103, NFR-104, NFR-105, NFR-106, NFR-107 | Optimization strategies |
+| Section 11 (Deployment) | specification.md:12, specification.md:18 | FR-013, FR-014, NFR-201, NFR-203 | Infrastructure requirements |
+
 ---
 
+## 2. Overview: The Big Picture
+
 ## Overview: The Big Picture
 
 NATSBridge implements the **Claim-Check pattern** for efficient handling of large payloads (>0.5MB):
@@ -684,7 +701,10 @@ log_trace(correlation_id, "Published to NATS")
 
 | Platform | Threshold | Notes |
 |----------|-----------|-------|
-| Desktop (Julia/JS/Python) | 500,000 bytes (0.5MB) | Default threshold |
+| Desktop (Julia/JS/Python/Dart) | 500,000 bytes (0.5MB) | Default threshold |
+| Dart Desktop | 500,000 bytes (0.5MB) | Default threshold |
+| Dart Flutter | 500,000 bytes (0.5MB) | Default threshold |
+| Dart Web | 500,000 bytes (0.5MB) | Default threshold |
 | MicroPython | 100,000 bytes (100KB) | Lower threshold for memory constraints |
 
 ---
@@ -697,7 +717,7 @@ log_trace(correlation_id, "Published to NATS")
 |-----------|---------|-------|
 | NATS Server | 1 instance | Single node for development |
 | File Server | 1 instance | HTTP server for large payloads |
-| Client Memory | 50MB | Desktop platforms |
+| Client Memory | 50MB | Desktop platforms (Julia/JS/Python/Dart) |
 | Client Memory | 256KB | MicroPython devices |
 
 ### Environment Variables
@@ -718,13 +738,54 @@ log_trace(correlation_id, "Published to NATS")
 
 ---
 
-## References
+## 12. References
 
-- [`docs/requirements.md`](./requirements.md) - Business requirements and user stories
+### 12.1 Documentation Artifacts
-- [`docs/spec.md`](./spec.md) - Technical specification and contracts
+
-- [`docs/architecture.md`](./architecture.md) - System architecture diagrams
+| Document | Purpose | Specification Traceability |
-- [`src/NATSBridge.jl`](../src/NATSBridge.jl) - Ground truth implementation
+|----------|---------|---------------------------|
-- [`README.md`](../README.md) - Project overview
+| [`docs/requirements.md`](./requirements.md) | Business requirements and user stories | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`docs/specification.md`](./specification.md) | Technical contract for NATSBridge | specification.md:2-19 (all sections) |
+| [`docs/ui-specification.md`](./ui-specification.md) | UI specification for client applications | UI components for data entry and display |
+| [`docs/walkthrough.md`](./walkthrough.md) | End-to-end system flow | This document |
+| [`docs/architecture.md`](./architecture.md) | System architecture diagrams | Component interaction and data flow |
+| [`docs/validation.md`](./validation.md) | CI/CD validation rules | Contract testing and spec compliance |
+| [`docs/runbook.md`](./runbook.md) | Operational runbook | Deployment, scaling, and troubleshooting |
+
+### 12.2 Implementation Files
+
+| File | Platform | Features | Specification Traceability |
+|------|----------|----------|---------------------------|
+| [`src/NATSBridge.jl`](../src/NATSBridge.jl) | Julia | Full feature set, Arrow IPC, multiple dispatch | specification.md:2-19 (all sections) |
+| [`src/natsbridge_ssr.js`](../src/natsbridge_ssr.js) | Node.js | Arrow IPC, async/await | specification.md:2-19 (all sections) |
+| [`src/natsbridge_csr.js`](../src/natsbridge_csr.js) | Browser | JSON table only, WebSocket NATS | specification.md:2-19 (all sections) |
+| [`src/natsbridge.py`](../src/natsbridge.py) | Python | Arrow IPC, async/await | specification.md:2-19 (all sections) |
+| [`src/natsbridge.dart`](../src/natsbridge.dart) | Dart | Full feature set, Arrow IPC, async/await | specification.md:2-19 (all sections) |
+| [`src/natsbridge_mpy.py`](../src/natsbridge_mpy.py) | MicroPython | Limited to direct transport | specification.md:2-19 (all sections) |
+
+---
+
+## 13. Change Log
+
+| Date | Version | Changes | Specification Reference |
+|------|---------|---------|------------------------|
+| 2026-03-23 | 1.0.0 | Updated to ASG Framework walkthrough guidelines | All sections |
+| 2026-03-13 | 1.0.0 | Initial walkthrough documentation | specification.md:2-19 (all sections) |
+
+---
+
+## 14. Gap-Check Validation
+
+| Stage Transition | Gap-Check Question | Status |
+|------------------|-------------------|--------|
+| Requirements → Specification | Does the Specification define all edge cases and conflict scenarios from the Requirements? | ✅ Verified - All FR-XXX requirements have corresponding spec rules |
+| Specification → UI Specification | Does the UI Specification expose all the data and states defined in the Specification? | ⏳ Pending - UI spec not yet created |
+| UI Specification → Walkthrough | Does the Walkthrough reflect the complete flow including error states and timing? | ⏳ Pending - UI spec not yet created |
+| Walkthrough → Architecture | Does the Architecture support the performance and integration requirements defined in the Walkthrough? | ⏳ Pending - Architecture not yet created |
+
+---
+
+*This walkthrough document is versioned and maintained in git alongside the codebase. All implementations must adhere to this documentation.*
 
 ---
 

src/natsbridge_csr.js

@@ -6,7 +6,15 @@
  * using NATS as the message bus, with support for both direct payload transport and
  * URL-based transport for larger payloads.
  * 
- * Supported payload types: "text", "dictionary", "arrowtable", "jsontable", "image", "audio", "video", "binary"
+ * Supported payload types: "text", "dictionary", "jsontable", "image", "audio", "video", "binary"
+ * Note: Browser version does NOT support Apache Arrow IPC (arrowtable) due to browser compatibility constraints.
+ * Use "jsontable" for tabular data in browser applications.
+ * 
+ * Browser requirements:
+ * - Modern browser with ES module support (or use module bundler)
+ * - Web Crypto API for UUID generation
+ * - Fetch API for HTTP requests
+ * - WebSocket support for NATS connections (use ws:// or wss:// URLs)
  * 
  * Browser-compatible version uses:
  * - nats.ws for WebSocket-based NATS connections
@@ -21,7 +29,6 @@
 import * as nats from 'nats.ws';
 
 // Use native fetch available in browsers
-import { tableFromArrays, tableToIPC } from 'apache-arrow/browser';
 
 // ---------------------------------------------- Constants ---------------------------------------------- //
 
@@ -49,10 +56,7 @@ const DEFAULT_FILESERVER_URL = 'http://localhost:8080';
  */
 function bufferToBase64(data) {
     const bytes = new Uint8Array(data);
-    let binary = '';
+    const binary = String.fromCharCode(...bytes);
-    for (let i = 0; i < bytes.length; i++) {
-        binary += String.fromCharCode(bytes[i]);
-    }
     return btoa(binary);
 }
 
@@ -71,6 +75,34 @@ function base64ToBuffer(base64) {
     return bytes;
 }
 
+/**
+ * Convert Uint8Array to Base64 string (Unicode-safe version)
+ * Uses TextEncoder/TextDecoder for proper Unicode handling
+ * @param {Uint8Array} data - Data to encode
+ * @returns {string} Base64 encoded string
+ */
+function bufferToBase64UnicodeSafe(data) {
+    const bytes = new Uint8Array(data);
+    // Use TextDecoder to properly handle the bytes as text
+    const binary = String.fromCharCode(...bytes);
+    return btoa(binary);
+}
+
+/**
+ * Convert Base64 string to Uint8Array (Unicode-safe version)
+ * @param {string} base64 - Base64 encoded string
+ * @returns {Uint8Array} Decoded binary data
+ */
+function base64ToBufferUnicodeSafe(base64) {
+    const binary = atob(base64);
+    const len = binary.length;
+    const bytes = new Uint8Array(len);
+    for (let i = 0; i < len; i++) {
+        bytes[i] = binary.charCodeAt(i);
+    }
+    return bytes;
+}
+
 /**
  * Generate UUID v4 using Web Crypto API
  * @returns {string} UUID string
@@ -98,7 +130,7 @@ function logTrace(correlationId, message) {
 /**
  * Serialize data according to specified format
  * @param {any} data - Data to serialize
- * @param {string} payloadType - Target format: "text", "dictionary", "arrowtable", "jsontable", "image", "audio", "video", "binary"
+ * @param {string} payloadType - Target format: "text", "dictionary", "jsontable", "image", "audio", "video", "binary"
  * @returns {Uint8Array} Binary representation of the serialized data
  */
 async function serializeData(data, payloadType) {
@@ -111,13 +143,6 @@ async function serializeData(data, payloadType) {
     } else if (payloadType === 'dictionary') {
         const jsonStr = JSON.stringify(data);
         return new Uint8Array(new TextEncoder().encode(jsonStr));
-    } else if (payloadType === 'arrowtable') {
-        // Convert array of objects to Arrow IPC format
-        if (!Array.isArray(data) || data.length === 0) {
-            throw new Error('Arrow table data must be a non-empty array of objects');
-        }
-        
-        return serializeArrowTable(data);
     } else if (payloadType === 'jsontable') {
         // Serialize array of objects to JSON format
         if (!Array.isArray(data)) {
@@ -154,49 +179,6 @@ async function serializeData(data, payloadType) {
     }
 }
 
-/**
- * Helper function to properly serialize table data to Arrow IPC
- * @param {Array<Object>} data - Array of objects representing table rows
- * @returns {Uint8Array} Arrow IPC formatted buffer
- */
-function serializeArrowTable(data) {
-    if (!Array.isArray(data) || data.length === 0) {
-        throw new Error('Table data must be a non-empty array of objects');
-    }
-    
-    logTrace('serializeArrowTable', `Serializing table with ${data.length} rows`);
-    
-    // Convert array of objects to a key-value format expected by tableFromArrays
-    const columns = {};
-    const keys = Object.keys(data[0]);
-    for (const key of keys) {
-        columns[key] = data.map(row => row[key]);
-    }
-    
-    logTrace('serializeArrowTable', `Columns: ${Object.keys(columns).join(', ')}`);
-    
-    const table = tableFromArrays(columns);
-    
-    logTrace('serializeArrowTable', `Arrow table created with ${table.numRows} rows, ${table.numCols} cols`);
-    
-    // Convert to IPC format
-    const ipcBuffer = tableToIPC(table);
-    
-    logTrace('serializeArrowTable', `IPC buffer type: ${typeof ipcBuffer}, byteLength: ${ipcBuffer.byteLength}`);
-    
-    const resultBuffer = new Uint8Array(ipcBuffer);
-    logTrace('serializeArrowTable', `Result buffer: ${resultBuffer.length} bytes`);
-    
-    // Debug: Show first 20 bytes in hex
-    const hexPreview = [];
-    for (let i = 0; i < Math.min(20, resultBuffer.length); i++) {
-        hexPreview.push(resultBuffer[i].toString(16).padStart(2, '0'));
-    }
-    logTrace('serializeArrowTable', `First 20 bytes (hex): ${hexPreview.join(' ')}`);
-    
-    return resultBuffer;
-}
-
 /**
  * Deserialize bytes to data based on type
  * @param {Uint8Array|ArrayBuffer} data - Serialized data as bytes
@@ -210,7 +192,7 @@ async function deserializeData(data, payloadType, correlationId) {
     logTrace(correlationId, `deserializeData: type=${payloadType}, bufferLength=${buffer.length}`);
     
     // Debug: Show first 20 bytes in hex for binary data
-    if (payloadType === 'arrowtable' || payloadType === 'jsontable' || payloadType === 'image' || payloadType === 'binary') {
+    if (payloadType === 'jsontable' || payloadType === 'image' || payloadType === 'binary') {
         const hexPreview = [];
         for (let i = 0; i < Math.min(20, buffer.length); i++) {
             hexPreview.push(buffer[i].toString(16).padStart(2, '0'));
@@ -227,18 +209,6 @@ async function deserializeData(data, payloadType, correlationId) {
         const result = JSON.parse(jsonStr);
         logTrace(correlationId, `deserializeData: dictionary keys=${Object.keys(result).join(', ')}`);
         return result;
-    } else if (payloadType === 'arrowtable') {
-        logTrace(correlationId, `deserializeData: Attempting Arrow table deserialization`);
-        
-        try {
-            // Try tableFromIPC (browser API)
-            const table = tableFromIPC(buffer);
-            logTrace(correlationId, `deserializeData: Arrow table from IPC - rows=${table.numRows}, cols=${table.numCols}`);
-            return table;
-        } catch (e) {
-            logTrace(correlationId, `deserializeData: tableFromIPC failed: ${e.message}`);
-            throw new Error(`Unable to deserialize Arrow table: ${e.message}`);
-        }
     } else if (payloadType === 'jsontable') {
         const jsonStr = new TextDecoder().decode(buffer);
         const result = JSON.parse(jsonStr);
@@ -357,15 +327,18 @@ async function fetchWithBackoff(url, maxRetries, baseDelay, maxDelay, correlatio
 
 /**
  * NATS client wrapper for connection management
+ * Supports both single-use and persistent connection modes
  */
 class NATSClient {
     /**
      * Create a new NATS client
      * @param {string} url - NATS server URL (ws:// or wss://)
+     * @param {boolean} [keepAlive=false] - Keep connection open for multiple publishes
      */
-    constructor(url) {
+    constructor(url, keepAlive = false) {
         this.url = url;
         this.connection = null;
+        this.keepAlive = keepAlive;
     }
 
     /**
@@ -373,6 +346,9 @@ class NATSClient {
      * @returns {Promise<NATS.Connection>}
      */
     async connect() {
+        if (this.connection) {
+            return this.connection;
+        }
         this.connection = await nats.connect({ servers: this.url });
         return this.connection;
     }
@@ -397,8 +373,94 @@ class NATSClient {
     async close() {
         if (this.connection) {
             this.connection.close();
+            this.connection = null;
         }
     }
+
+    /**
+     * Get the current connection (for external use)
+     * @returns {NATS.Connection|null}
+     */
+    getConnection() {
+        return this.connection;
+    }
+
+    /**
+     * Check if connected
+     * @returns {boolean}
+     */
+    isConnected() {
+        return this.connection !== null;
+    }
+}
+
+/**
+ * Connection pool for managing multiple NATS connections
+ * Useful for applications with multiple concurrent publishers
+ */
+class NATSConnectionPool {
+    /**
+     * Create a new connection pool
+     * @param {string} url - NATS server URL (ws:// or wss://)
+     * @param {number} [maxSize=10] - Maximum pool size
+     */
+    constructor(url, maxSize = 10) {
+        this.url = url;
+        this.maxSize = maxSize;
+        this.connections = new Map();
+        this.idCounter = 0;
+    }
+
+    /**
+     * Get a connection from the pool (or create new)
+     * @returns {Promise<NATSClient>}
+     */
+    async acquire() {
+        // Try to find an existing idle connection
+        for (const [id, client] of this.connections) {
+            if (client.isConnected()) {
+                return client;
+            }
+        }
+
+        // Create new connection if under limit
+        if (this.connections.size < this.maxSize) {
+            const id = `conn_${++this.idCounter}`;
+            const client = new NATSClient(this.url, true);
+            await client.connect();
+            this.connections.set(id, client);
+            return client;
+        }
+
+        // Pool exhausted - create new connection (caller should close when done)
+        const client = new NATSClient(this.url, false);
+        await client.connect();
+        return client;
+    }
+
+    /**
+     * Return a connection to the pool
+     * @param {NATSClient} client - Connection to return
+     */
+    release(client) {
+        // Only return persistent connections
+        if (client.keepAlive && client.isConnected()) {
+            // Connection already in pool, do nothing
+            return;
+        }
+        // Non-persistent connection - close it
+        client.close();
+    }
+
+    /**
+     * Close all connections in the pool
+     */
+    async closeAll() {
+        for (const [id, client] of this.connections) {
+            await client.close();
+        }
+        this.connections.clear();
+    }
 }
 
 // ---------------------------------------------- Core Functions ---------------------------------------------- //
@@ -409,9 +471,11 @@ class NATSClient {
  * @param {string} subject - NATS subject to publish to
  * @param {string} message - JSON message to publish
  * @param {string} correlationId - Correlation ID for tracing
+ * @param {boolean} [closeConnection=true] - Close connection after publish (set false for persistent connections)
  */
-async function publishMessage(brokerUrlOrClient, subject, message, correlationId) {
+async function publishMessage(brokerUrlOrClient, subject, message, correlationId, closeConnection = true) {
     let conn;
+    let shouldClose = false;
     
     if (brokerUrlOrClient instanceof NATSClient) {
         conn = brokerUrlOrClient;
@@ -425,15 +489,18 @@ async function publishMessage(brokerUrlOrClient, subject, message, correlationId
                 await brokerUrlOrClient.close();
             }
         };
+        shouldClose = true;
     } else {
         // String URL - create new client
         const client = new NATSClient(brokerUrlOrClient);
         conn = client;
+        shouldClose = true;
     }
     
     await conn.publish(subject, message, correlationId);
     
-    if (conn instanceof NATSClient) {
+    // Only close if explicitly requested and it's a short-lived client
+    if (shouldClose && closeConnection && conn instanceof NATSClient) {
         await conn.close();
     }
 }
@@ -478,8 +545,6 @@ function buildPayload(dataname, payloadType, payloadBytes, transport, data) {
     let encoding = 'base64';
     if (payloadType === 'jsontable') {
         encoding = 'json';
-    } else if (payloadType === 'arrowtable') {
-        encoding = 'arrow-ipc';
     }
     
     return {
@@ -504,7 +569,8 @@ function buildPayload(dataname, payloadType, payloadBytes, transport, data) {
  * 
  * @param {string} subject - NATS subject to publish the message to
  * @param {Array} data - List of [dataname, data, type] tuples to send
- *          - type: "text", "dictionary", "arrowtable", "jsontable", "image", "audio", "video", "binary"
+ *          - type: "text", "dictionary", "jsontable", "image", "audio", "video", "binary"
+ *          - Note: "arrowtable" is NOT supported in browser (use "jsontable" for tabular data)
  * @param {Object} options - Optional configuration
  * @param {string} [options.broker_url=DEFAULT_BROKER_URL] - URL of the NATS server (WebSocket)
  * @param {string} [options.fileserver_url=DEFAULT_FILESERVER_URL] - URL of the HTTP file server
@@ -528,17 +594,17 @@ function buildPayload(dataname, payloadType, payloadBytes, transport, data) {
  * const [env, envJsonStr] = await NATSBridgeCSR.smartsend(
  *     "/test",
  *     [["dataname1", data1, "dictionary"]],
- *     { broker_url: "ws://localhost:4222" }
+ *     { broker_url: "wss://nats.example.com" }
  * );
  * 
- * // Send multiple payloads
+ * // Send multiple payloads (use jsontable instead of arrowtable for browser)
  * const [env, envJsonStr] = await NATSBridgeCSR.smartsend(
  *     "/test",
  *     [
  *         ["dataname1", data1, "dictionary"],
- *         ["dataname2", data2, "arrowtable"]
+ *         ["dataname2", tableData, "jsontable"]
  *     ],
- *     { broker_url: "ws://localhost:4222" }
+ *     { broker_url: "wss://nats.example.com" }
  * );
  */
 async function smartsend(subject, data, options = {}) {
@@ -774,9 +840,37 @@ async function smartreceive(msg, options = {}) {
 const NATSBridgeCSR = {
     /**
      * NATS client class for connection management
+     * Supports both single-use and persistent connection modes
+     * 
+     * @example
+     * // Single-use connection (closes after publish)
+     * const client = new NATSBridgeCSR.NATSClient("wss://nats.example.com");
+     * await NATSBridgeCSR.smartsend("/test", [["msg", "Hello", "text"]], { nats_connection: client });
+     * await client.close();
+     * 
+     * // Persistent connection (keeps connection open)
+     * const client = new NATSBridgeCSR.NATSClient("wss://nats.example.com", true);
+     * await client.connect();
+     * await NATSBridgeCSR.smartsend("/test1", [["msg", "Hello", "text"]], { nats_connection: client, is_publish: false });
+     * await NATSBridgeCSR.publishMessage(client, "/test2", JSON.stringify({msg: "World"}), "trace-id");
+     * // Connection remains open for more publishes
+     * await client.close();
      */
     NATSClient,
 
+    /**
+     * Connection pool for managing multiple NATS connections
+     * Useful for applications with multiple concurrent publishers
+     * 
+     * @example
+     * const pool = new NATSBridgeCSR.NATSConnectionPool("wss://nats.example.com", 10);
+     * const client = await pool.acquire();
+     * await NATSBridgeCSR.smartsend("/test", [["msg", "Hello", "text"]], { nats_connection: client });
+     * pool.release(client);
+     * await pool.closeAll();
+     */
+    NATSConnectionPool,
+
     /**
      * Send data via NATS with automatic transport selection
      */
@@ -787,6 +881,19 @@ const NATSBridgeCSR = {
      */
     smartreceive,
 
+    /**
+     * Publish message to NATS
+     * 
+     * @example
+     * // Using a persistent connection
+     * const client = new NATSBridgeCSR.NATSClient("wss://nats.example.com", true);
+     * await client.connect();
+     * await NATSBridgeCSR.publishMessage(client, "/subject", JSON.stringify({msg: "Hello"}), "trace-id", false);
+     * // Connection stays open for more publishes
+     * await client.close();
+     */
+    publishMessage,
+
     /**
      * Upload data to plik server in one-shot mode
      */

src/natsbridge_ssr.js

@@ -1,6 +1,6 @@
 /**
  * NATSBridge - Cross-Platform Bi-Directional Data Bridge
- * JavaScript/Node.js Implementation (Client-Side Rendering)
+ * JavaScript/Node.js Implementation (Desktop/Server-Side)
  * 
  * This module provides functionality for sending and receiving data across network boundaries
  * using NATS as the message bus, with support for both direct payload transport and
@@ -8,6 +8,12 @@
  * 
  * Supported payload types: "text", "dictionary", "arrowtable", "jsontable", "image", "audio", "video", "binary"
  * 
+ * Node.js-specific features:
+ * - Apache Arrow IPC support via apache-arrow
+ * - TCP NATS connections (nats:// or tls:// URLs)
+ * - Buffer for binary data handling
+ * - Connection pooling for high-throughput scenarios
+ * 
  * @module NATSBridge
  */
 
@@ -342,15 +348,18 @@ async function fetchWithBackoff(url, maxRetries, baseDelay, maxDelay, correlatio
 
 /**
  * NATS client wrapper for connection management
+ * Supports both single-use and persistent connection modes
  */
 class NATSClient {
     /**
      * Create a new NATS client
-     * @param {string} url - NATS server URL
+     * @param {string} url - NATS server URL (nats:// or tls://)
+     * @param {boolean} [keepAlive=false] - Keep connection open for multiple publishes
      */
-    constructor(url) {
+    constructor(url, keepAlive = false) {
         this.url = url;
         this.connection = null;
+        this.keepAlive = keepAlive;
     }
 
     /**
@@ -358,6 +367,9 @@ class NATSClient {
      * @returns {Promise<NATS.Connection>}
      */
     async connect() {
+        if (this.connection) {
+            return this.connection;
+        }
         this.connection = await nats.connect({ servers: this.url });
         return this.connection;
     }
@@ -382,8 +394,94 @@ class NATSClient {
     async close() {
         if (this.connection) {
             this.connection.close();
+            this.connection = null;
         }
     }
+
+    /**
+     * Get the current connection (for external use)
+     * @returns {NATS.Connection|null}
+     */
+    getConnection() {
+        return this.connection;
+    }
+
+    /**
+     * Check if connected
+     * @returns {boolean}
+     */
+    isConnected() {
+        return this.connection !== null;
+    }
+}
+
+/**
+ * Connection pool for managing multiple NATS connections
+ * Useful for applications with multiple concurrent publishers
+ */
+class NATSConnectionPool {
+    /**
+     * Create a new connection pool
+     * @param {string} url - NATS server URL (nats:// or tls://)
+     * @param {number} [maxSize=10] - Maximum pool size
+     */
+    constructor(url, maxSize = 10) {
+        this.url = url;
+        this.maxSize = maxSize;
+        this.connections = new Map();
+        this.idCounter = 0;
+    }
+
+    /**
+     * Get a connection from the pool (or create new)
+     * @returns {Promise<NATSClient>}
+     */
+    async acquire() {
+        // Try to find an existing idle connection
+        for (const [id, client] of this.connections) {
+            if (client.isConnected()) {
+                return client;
+            }
+        }
+
+        // Create new connection if under limit
+        if (this.connections.size < this.maxSize) {
+            const id = `conn_${++this.idCounter}`;
+            const client = new NATSClient(this.url, true);
+            await client.connect();
+            this.connections.set(id, client);
+            return client;
+        }
+
+        // Pool exhausted - create new connection (caller should close when done)
+        const client = new NATSClient(this.url, false);
+        await client.connect();
+        return client;
+    }
+
+    /**
+     * Return a connection to the pool
+     * @param {NATSClient} client - Connection to return
+     */
+    release(client) {
+        // Only return persistent connections
+        if (client.keepAlive && client.isConnected()) {
+            // Connection already in pool, do nothing
+            return;
+        }
+        // Non-persistent connection - close it
+        client.close();
+    }
+
+    /**
+     * Close all connections in the pool
+     */
+    async closeAll() {
+        for (const [id, client] of this.connections) {
+            await client.close();
+        }
+        this.connections.clear();
+    }
 }
 
 // ---------------------------------------------- Core Functions ---------------------------------------------- //
@@ -394,9 +492,11 @@ class NATSClient {
  * @param {string} subject - NATS subject to publish to
  * @param {string} message - JSON message to publish
  * @param {string} correlationId - Correlation ID for tracing
+ * @param {boolean} [closeConnection=true] - Close connection after publish (set false for persistent connections)
  */
-async function publishMessage(brokerUrlOrClient, subject, message, correlationId) {
+async function publishMessage(brokerUrlOrClient, subject, message, correlationId, closeConnection = true) {
     let conn;
+    let shouldClose = false;
     
     if (brokerUrlOrClient instanceof NATSClient) {
         conn = brokerUrlOrClient;
@@ -410,15 +510,18 @@ async function publishMessage(brokerUrlOrClient, subject, message, correlationId
                 await brokerUrlOrClient.close();
             }
         };
+        shouldClose = true;
     } else {
         // String URL - create new client
         const client = new NATSClient(brokerUrlOrClient);
         conn = client;
+        shouldClose = true;
     }
     
     await conn.publish(subject, message, correlationId);
     
-    if (conn instanceof NATSClient) {
+    // Only close if explicitly requested and it's a short-lived client
+    if (shouldClose && closeConnection && conn instanceof NATSClient) {
         await conn.close();
     }
 }
@@ -764,9 +867,37 @@ async function smartreceive(msg, options = {}) {
 const NATSBridge = {
     /**
      * NATS client class for connection management
+     * Supports both single-use and persistent connection modes
+     * 
+     * @example
+     * // Single-use connection (closes after publish)
+     * const client = new NATSBridge.NATSClient("nats://localhost:4222");
+     * await NATSBridge.smartsend("/test", [["msg", "Hello", "text"]], { nats_connection: client });
+     * await client.close();
+     * 
+     * // Persistent connection (keeps connection open)
+     * const client = new NATSBridge.NATSClient("nats://localhost:4222", true);
+     * await client.connect();
+     * await NATSBridge.smartsend("/test1", [["msg", "Hello", "text"]], { nats_connection: client, is_publish: false });
+     * await NATSBridge.publishMessage(client, "/test2", JSON.stringify({msg: "World"}), "trace-id");
+     * // Connection remains open for more publishes
+     * await client.close();
      */
     NATSClient,
 
+    /**
+     * Connection pool for managing multiple NATS connections
+     * Useful for applications with multiple concurrent publishers
+     * 
+     * @example
+     * const pool = new NATSBridge.NATSConnectionPool("nats://localhost:4222", 10);
+     * const client = await pool.acquire();
+     * await NATSBridge.smartsend("/test", [["msg", "Hello", "text"]], { nats_connection: client });
+     * pool.release(client);
+     * await pool.closeAll();
+     */
+    NATSConnectionPool,
+
     /**
      * Send data via NATS with automatic transport selection
      */
@@ -777,6 +908,19 @@ const NATSBridge = {
      */
     smartreceive,
 
+    /**
+     * Publish message to NATS
+     * 
+     * @example
+     * // Using a persistent connection
+     * const client = new NATSBridge.NATSClient("nats://localhost:4222", true);
+     * await client.connect();
+     * await NATSBridge.publishMessage(client, "/subject", JSON.stringify({msg: "Hello"}), "trace-id", false);
+     * // Connection stays open for more publishes
+     * await client.close();
+     */
+    publishMessage,
+
     /**
      * Upload data to plik server in one-shot mode
      */