diff --git a/docs/architecture.md b/docs/architecture.md
index 470c2a6..458677f 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -10,7 +10,7 @@
 
 ## 1. Executive Summary
 
-This document defines the **blueprint** for msghandler - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, **Rust**, and **MicroPython** applications using NATS as the message bus.
+This document defines the **blueprint** for msghandler - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, **Rust**, and **MicroPython** applications using a message broker as the transport layer.
 
 This architecture document serves as the single source of truth for:
 - **System Structure**: How components fit together and interact
@@ -47,26 +47,25 @@ This architecture document serves as the single source of truth for:
 
 ```mermaid
 flowchart TD
-    subgraph "External Systems"
-        NATS_Server[NATS Server]
+   subgraph "External Systems"
+        Message_Broker[Message Broker<br/>NATS/MQTT/WebSocket/Custom]
         File_Server[HTTP File Server<br/>Plik/AWS S3/Custom]
     end
 
-    subgraph "Client Applications"
-        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]
-        Rust_App[Rust Application<br/>Server/Desktop]
-        MicroPython_App[MicroPython Device]
+    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]
+    Rust_App[Rust Application<br/>Server/Desktop]
+    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
-    Rust_App -->|NATS| NATS_Server
-    MicroPython_App -->|NATS| NATS_Server
+    Julia_App -->|Transport| Message_Broker
+    JS_App -->|Transport| Message_Broker
+    Python_App -->|Transport| Message_Broker
+    Dart_App -->|Transport| Message_Broker
+    Rust_App -->|Transport| Message_Broker
+    MicroPython_App -->|Transport| Message_Broker
 
     Julia_App -->|HTTP| File_Server
     JS_App -->|HTTP| File_Server
@@ -75,7 +74,7 @@ flowchart TD
     Rust_App -->|HTTP| File_Server
     MicroPython_App -->|HTTP| File_Server
 
-    style NATS_Server fill:#fff3e0,stroke:#f57c00
+    style Message_Broker fill:#fff3e0,stroke:#f57c00
     style File_Server fill:#f3e5f5,stroke:#9c27b4
     style Julia_App fill:#e8f5e9,stroke:#4caf50
     style JS_App fill:#e3f2fd,stroke:#2196f3
@@ -98,14 +97,14 @@ flowchart TD
         MicroPython_Module[MicroPython msghandler Module]
     end
 
-    Julia_Module --> NATS_Client
-    JS_Module --> NATS_Client
-    Python_Module --> NATS_Client
-    Dart_Module --> NATS_Client
-    Rust_Module --> NATS_Client
-    MicroPython_Module --> NATS_Client
+    Julia_Module --> Transport_Client
+    JS_Module --> Transport_Client
+    Python_Module --> Transport_Client
+    Dart_Module --> Transport_Client
+    Rust_Module --> Transport_Client
+    MicroPython_Module --> Transport_Client
 
-    NATS_Client --> NATS_Broker
+    Transport_Client --> Message_Broker
 
     Julia_Module --> File_Client
     JS_Module --> File_Client
@@ -122,7 +121,7 @@ flowchart TD
     style Dart_Module fill:#fff0f6,stroke:#e91e63
     style Rust_Module fill:#dea584,stroke:#e65100
     style MicroPython_Module fill:#fce4ec,stroke:#e91e63
-    style NATS_Broker fill:#fff3e0,stroke:#f57c00
+    style Message_Broker fill:#fff3e0,stroke:#f57c00
     style File_Server fill:#f3e5f5,stroke:#9c27b4
 ```
 
@@ -174,8 +173,8 @@ flowchart TD
 
 | Component | Purpose | Platform Support |
 |-----------|---------|------------------|
-| **smartsend** | Send data via NATS with automatic transport selection, returns (envelope, json_string) for caller to publish | All |
-| **smartreceive** | Receive and process NATS messages from JSON string | All |
+| **smartsend** | Send data with automatic transport selection, returns (envelope, json_string) for caller to publish via transport | All |
+| **smartreceive** | Receive and process messages from JSON string | All |
 | **_serialize_data** | Serialize data according to payload type | All |
 | **_deserialize_data** | Deserialize bytes to native data types | All |
 | **envelope_to_json** | Convert msg_envelope_v1 struct to JSON string | All |
@@ -224,7 +223,7 @@ struct msg_envelope_v1
   msg_id::String               # UUID v4 for this message
   timestamp::String            # ISO 8601 UTC timestamp
   
-  send_to::String              # NATS subject to publish to
+  send_to::String              # Topic/subject to publish to
   msg_purpose::String          # ACK, NACK, updateStatus, shutdown, chat
   sender_name::String          # Sender application name
   sender_id::String            # UUID v4 of sender
@@ -233,7 +232,7 @@ struct msg_envelope_v1
   
   reply_to::String             # Topic for reply messages
   reply_to_msg_id::String      # Message ID being replied to
-  broker_url::String           # NATS broker URL
+  broker_url::String           # Broker URL for the transport layer
   
   metadata::Dict{String, Any}  # Message-level metadata
   payloads::Vector{msg_payload_v1}  # List of payloads
@@ -436,13 +435,13 @@ JavaScript uses async/await for non-blocking I/O:
 
 #### Node.js Implementation (msghandler_ssr.js)
 
-- **TCP NATS connections**: Uses `nats://` or `tls://` URLs
+- **Transport connections**: Uses broker URLs (e.g., `nats://`, `mqtt://`, `ws://`)
 - **Apache Arrow IPC**: Full support via `apache-arrow`
 - **Buffer for binary data**: Native Node.js Buffer handling
 
 #### Browser Implementation (msghandler_csr.js)
 
-- **WebSocket NATS connections**: Uses `ws://` or `wss://` URLs via `nats.ws`
+- **WebSocket connections**: Uses `ws://` or `wss://` URLs (transport-agnostic)
 - **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()`
@@ -474,7 +473,7 @@ Dart uses classes for stateful operations with async/await:
 - **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)
+- **Transport package**: Transport client with WebSocket support (Dart Web)
 
 ```dart
 class msghandler {
@@ -484,7 +483,7 @@ class msghandler {
   final String fileserverUrl;
   
   msghandler({
-    this.brokerUrl = 'nats://localhost:4222',
+    this.brokerUrl = DEFAULT_BROKER_URL,
     this.fileserverUrl = 'http://localhost:8080',
   });
 }
@@ -492,19 +491,19 @@ class msghandler {
 
 #### Dart Desktop (Dart SDK)
 
-- **TCP NATS connections**: Uses `nats://` or `tls://` URLs
+- **Transport connections**: Uses broker URLs (e.g., `nats://`, `mqtt://`)
 - **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
+- **Transport connections**: Uses broker URLs (e.g., `nats://`, `mqtt://`)
 - **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
+- **WebSocket connections**: Uses `ws://` or `wss://` URLs (transport-agnostic)
 - **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
@@ -516,7 +515,7 @@ 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
+- **WebSocket transport**: Uses transport client for browser-compatible connections
 - **Fetch API**: HTTP file server communication via fetch
 
 ### MicroPython Architecture
@@ -540,7 +539,7 @@ Rust leverages compile-time type safety and async runtimes:
 
 - **Type-safe payloads**: Rust enum discriminates between `Text`, `Dictionary`, `ArrowTable`, `Binary`, etc.
 - **serde serialization**: Automatic JSON deserialization via `#[derive(Serialize, Deserialize)]`
-- **tokio runtime**: Efficient async I/O for NATS connections and HTTP file server operations
+- **tokio runtime**: Efficient async I/O for transport connections and HTTP file server operations
 - **arrow2 integration**: Native Arrow IPC deserialization without intermediate format conversion
 - **reqwest**: High-performance HTTP client with built-in TLS and connection pooling
 - **Zero-copy patterns**: `Vec<u8>` passed directly to avoid unnecessary memory copies
@@ -572,8 +571,8 @@ pub struct SmartsendOptions {
     // ... other fields
 }
 
-// NATS client with tokio integration
-let conn = nats::connect("nats://localhost:4222").await?;
+// Transport client with tokio integration
+let conn = transport_client::connect(DEFAULT_BROKER_URL).await?;
 
 // Subscribe and process messages
 let mut sub = conn.subscribe("/agent/wine/api/v1/analyze")?;
@@ -599,7 +598,7 @@ for msg in sub.messages() {
 
 | Component | Scaling Strategy |
 |-----------|------------------|
-| **NATS Server** | Cluster deployment with multiple nodes |
+| **Message Broker** | Cluster deployment with multiple nodes |
 | **File Server** | Load balancer + multiple instances |
 | **Client Applications** | Deploy multiple instances behind load balancer |
 
@@ -607,7 +606,7 @@ for msg in sub.messages() {
 
 | Component | Scaling Strategy |
 |-----------|------------------|
-| **NATS Server** | Increase memory, CPU, disk I/O |
+| **Message Broker** | Increase memory, CPU, disk I/O |
 | **File Server** | Increase memory, CPU, disk capacity |
 | **Client Applications** | Increase heap size (Python/JS) |
 
@@ -617,7 +616,7 @@ for msg in sub.messages() {
 |--------|--------|-------|
 | Message serialization overhead | <50ms | For 10KB payload |
 | Message deserialization overhead | <50ms | For 10KB payload |
-| NATS connection establishment | <100ms | Connection pool recommended |
+| Transport connection establishment | <100ms | Connection pool recommended |
 | File upload latency | <1s | For 0.5MB file |
 | File download latency | <1s | For 0.5MB file |
 
@@ -625,16 +624,16 @@ for msg in sub.messages() {
 
 ## Failure Modes and Recovery
 
-### NATS Connection Failure
+### Transport Connection Failure
 
-**Scenario**: NATS server unavailable
+**Scenario**: Message broker unavailable
 
 **Handler**:
-- Connection auto-reconnect via TCP-level reconnection
+- Connection auto-reconnect via transport-level reconnection
 - Retry with exponential backoff for publish operations
 
 **Recovery**:
-- NATS client automatically attempts reconnection
+- Transport client automatically attempts reconnection
 - Application can check connection status before publishing
 
 ### File Server Unavailable
@@ -697,7 +696,7 @@ for msg in sub.messages() {
 
 **Rationale**:
 - Simplifies JSON serialization (all data is string-compatible)
-- Increases payload size by ~33%, but NATS can handle this
+- Increases payload size by ~33%, but transport can handle this
 - Alternative would be binary payload support (more complex)
 
 ### Decision 3: Multiple Platform Implementations
@@ -730,7 +729,7 @@ for msg in sub.messages() {
 
 | Component | Minimum | Notes |
 |-----------|---------|-------|
-| NATS Server | 1 instance | Single node for development |
+| Message Broker | 1 instance | Single node for development |
 | File Server | 1 instance | HTTP server for large payloads |
 | Client Memory | 50MB | Desktop platforms (Julia/JS/Python/Dart) |
 | Client Memory | 256KB | MicroPython devices |
@@ -739,7 +738,7 @@ for msg in sub.messages() {
 
 | Variable | Default | Description |
 |----------|---------|-------------|
-| `NATS_URL` | `nats://localhost:4222` | NATS server URL |
+| `BROKER_URL` | `ws://localhost:4222` | Message broker URL |
 | `FILESERVER_URL` | `http://localhost:8080` | HTTP file server URL |
 | `SIZE_THRESHOLD` | `500000` | Size threshold in bytes (0.5MB) |
 
@@ -748,15 +747,15 @@ for msg in sub.messages() {
 ```mermaid
 flowchart TD
     subgraph "Docker Network"
-        NATS_Container[NATS Server]
+        Broker_Container[Message Broker]
         FileServer_Container[Plik File Server]
         App_Container[Application Container]
     end
     
-    App_Container -->|NATS| NATS_Container
+    App_Container -->|Transport| Broker_Container
     App_Container -->|HTTP| FileServer_Container
     
-    style NATS_Container fill:#fff3e0,stroke:#f57c00
+    style Broker_Container fill:#fff3e0,stroke:#f57c00
     style FileServer_Container fill:#f3e5f5,stroke:#9c27b4
     style App_Container fill:#e3f2fd,stroke:#2196f3
 ```
@@ -775,11 +774,12 @@ flowchart TD
 
 ### Transport Security
 
-**Mechanism**: TLS support for NATS connections
+**Mechanism**: TLS support for transport connections
 
 **Implementation**:
 - Use `nats://` URL for plain text
 - Use `tls://` URL for TLS-encrypted connections
+- Use `ws://` or `wss://` for WebSocket connections
 
 ### File Server Security
 
@@ -835,6 +835,11 @@ flowchart TD
 
 | Date | Version | Changes |
 |------|---------|---------|
+| 2026-05-15 | 1.5.0 | Made transport layer agnostic | All sections |
+| - | - | Removed all NATS-specific references from architecture docs | All sections |
+| - | - | Updated diagrams to use generic "Message Broker" instead of "NATS Server" | All sections |
+| - | - | Updated code examples to use transport-agnostic patterns | All sections |
+| - | - | Removed NATS client packages from external dependencies | All sections |
 | 2026-05-14 | 1.4.0 | Updated Rust API to reflect `smartreceive` deserialization changes | All sections |
 | - | - | `smartreceive` now stores deserialized data in `MsgPayloadV1.data` | specification.md:8 |
 | - | - | Added `plik_upload_file` convenience function to component table | specification.md:13 |
@@ -849,6 +854,7 @@ flowchart TD
 | 2026-05-13 | 1.2.0 | Aligned with ground truth implementation (src/msghandler.jl) |
 | - | - | Removed publish_message component (commented out in source) |
 | - | - | Removed NATSClient and NATSConnectionPool classes (not in ground truth) |
+| - | - | Updated smartsend to return JSON for caller to publish via transport |
 | - | - | Updated component diagram to match actual module structure |
 | - | - | Updated data flow to show smartsend returns JSON for caller to publish |
 | - | - | Fixed SIZE_THRESHOLD default to 500,000 bytes |
@@ -856,6 +862,7 @@ flowchart TD
 | - | - | Added NATSClient with keepAlive support |
 | - | - | Added NATSConnectionPool for connection reuse |
 | - | - | Added publishMessage function with closeConnection option |
+| (Historical - pre-transport-agnostic refactor) | | |
 | 2026-03-13 | 1.0.0 | Initial architecture documentation |
 
 ---
@@ -880,7 +887,7 @@ flowchart TD
 |------|----------|----------|---------------------------|-------------------|
 | [`src/msghandler.jl`](../src/msghandler.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/msghandler_ssr.js`](../src/msghandler_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/msghandler_csr.js`](../src/msghandler_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/msghandler_csr.js`](../src/msghandler_csr.js) | Browser | JSON table only | specification.md:2-19 (all sections) | FR-001 through FR-014, NFR-101 through NFR-405 |
 | [`src/msghandler.py`](../src/msghandler.py) | Python | Arrow IPC, async/await | specification.md:2-19 (all sections) | FR-001 through FR-014, NFR-101 through NFR-405 |
 | [`src/msghandler.dart`](../src/msghandler.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/msghandler.rs`](../src/msghandler.rs) | Rust | Full feature set, Arrow IPC, async/await, type-safe, file upload helpers | specification.md:2-19 (all sections) | FR-001 through FR-014, NFR-101 through NFR-405 |
@@ -889,24 +896,18 @@ flowchart TD
 ### 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 |
+| Browser | - | - | Transport-agnostic (caller provides) | 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 |
-| Rust | nats | Latest | NATS client | specification.md:11 | FR-013, FR-014 |
 | Rust | serde | Latest | JSON serialization | specification.md:11 | FR-012, NFR-101, NFR-102 |
 | Rust | serde_json | Latest | JSON handling | specification.md:11 | FR-012, NFR-101, NFR-102 |
 | Rust | tokio | Latest | Async runtime | specification.md:11 | FR-013, FR-014 |
diff --git a/docs/requirements.md b/docs/requirements.md
index f6b9198..fc20b68 100644
--- a/docs/requirements.md
+++ b/docs/requirements.md
@@ -11,7 +11,7 @@
 
 ### 1.1 Business Goal
 
-msghandler is a cross-platform, bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, **Rust**, 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.
+msghandler is a cross-platform, bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, **Rust**, and **MicroPython** applications using a message broker as the transport layer. 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 the transport layer.
 
 ### 1.2 User Stories (with acceptance criteria)
 
@@ -19,13 +19,13 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 |-------|----------|---------------------|
 | **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 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 the transport layer |
 | **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 Dart developer**, I want to send large files (>0.5MB) | P1 | Large files are automatically uploaded to file server and URLs are sent via the transport layer |
 | **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 Rust developer**, I want to send and receive messages with type-safe APIs | P1 | Rust implementation uses serde for serialization, tokio for async, and nats-io for NATS connectivity |
+| **As a Rust developer**, I want to send and receive messages with type-safe APIs | P1 | Rust implementation uses serde for serialization, tokio for async, and transport-agnostic client for connectivity |
 | **As a developer**, I want to send mixed-content messages (text + image + file) | P1 | msghandler accepts list of (dataname, data, type) tuples and handles each payload appropriately |
 | **As a developer**, I want to receive multi-payload messages | P1 | msghandler 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 |
@@ -59,37 +59,32 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 | 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 |
+| Transport communication | Publishing and subscription via message broker (NATS, MQTT, WebSocket, etc.) |
 
 ### 2.2 Out of Scope
 
 | Feature | Reason |
 |---------|--------|
-| NATS JetStream support | Core NATS sufficient for current use cases |
+| Advanced transport features | Basic transport sufficient for current use cases |
 | Message compression | Compression adds complexity without clear benefit |
 | Message encryption | Payload encryption is application-layer concern |
-| Persistent message queues | NATS request-reply pattern sufficient |
-| Advanced routing rules | Simple NATS subject matching sufficient |
+| Persistent message queues | Transport request-reply pattern sufficient |
+| Advanced routing rules | Simple topic matching sufficient |
 
 ### 2.3 Dependencies
 
 | 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 |
-| Browser | nats.ws | Latest stable |
-| Dart | nats | Latest stable |
+| Browser | - | Transport-agnostic (caller provides) |
 | Dart | http | Latest stable |
 | Dart | uuid | Latest stable |
-| Rust | nats | Latest stable |
 | Rust | serde | Latest stable |
 | Rust | serde_json | Latest stable |
 | Rust | tokio | Latest stable |
@@ -100,7 +95,7 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 | Platform | Minimum Version | Notes |
 |----------|-----------------|-------|
 | Julia | 1.7+ | Arrow.jl required for arrowtable support |
-| Node.js | 16+ | nats.js required, Arrow IPC supported |
+| Node.js | 16+ | Transport client 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) |
@@ -115,8 +110,8 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 |----|-------------|-------------|
 | **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 |
-| **FR-003** | Large file handling | System shall automatically detect payloads ≥0.5MB and upload them to HTTP file server instead of sending via NATS |
-| **FR-004** | Direct transport for small payloads | System shall send payloads <0.5MB directly via NATS without file server upload |
+| **FR-003** | Large file handling | System shall automatically detect payloads ≥0.5MB and upload them to HTTP file server instead of sending via transport |
+| **FR-004** | Direct transport for small payloads | System shall send payloads <0.5MB directly via transport without file server upload |
 | **FR-005** | MicroPython support | System shall support payloads <100KB on MicroPython devices using direct transport |
 | **FR-006** | Multi-payload messages | System shall accept and process lists of (dataname, data, type) tuples |
 | **FR-007** | Payload type preservation | System shall preserve payload types when returning multi-payload messages |
@@ -125,8 +120,8 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 | **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 |
 | **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 |
-| **FR-013** | NATS publishing | System shall return JSON string representation for caller to publish to NATS subjects (caller is responsible for actual NATS publish) |
-| **FR-014** | NATS subscription | System shall receive and process NATS messages by accepting JSON string from NATS payload |
+| **FR-013** | Transport publishing | System shall return JSON string representation for caller to publish via transport layer (caller is responsible for actual transport publish) |
+| **FR-014** | Transport subscription | System shall receive and process messages by accepting JSON string from transport payload |
 
 ---
 
@@ -138,10 +133,10 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 |----|-------------|---------------|-------------|
 | **NFR-101** | Message serialization overhead | <50ms for 10KB payload | Benchmark tests |
 | **NFR-102** | Message deserialization overhead | <50ms for 10KB payload | Benchmark tests |
-| **NFR-103** | NATS connection establishment | <100ms | Connection pool benchmarks |
+| **NFR-103** | Transport connection establishment | <100ms | Connection pool benchmarks |
 | **NFR-104** | File upload latency | <1s for 0.5MB file | Integration tests |
 | **NFR-105** | File download latency | <1s for 0.5MB file | Integration tests |
-| **NFR-106** | Concurrent connections | Support 100+ simultaneous NATS connections | Scale testing |
+| **NFR-106** | Concurrent connections | Support 100+ simultaneous transport connections | Scale testing |
 | **NFR-107** | Message throughput | Handle 1000+ messages/second per instance | Load testing |
 | **NFR-108** | File server scalability | Support horizontal scaling of file server backend | Architecture review |
 
@@ -149,16 +144,16 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 
 | ID | Requirement | Specification |
 |----|-------------|---------------|
-| **NFR-201** | Message delivery | At-least-once delivery semantics via NATS |
+| **NFR-201** | Message delivery | At-least-once delivery semantics via transport |
 | **NFR-202** | File server availability | Graceful degradation when file server is unavailable |
-| **NFR-203** | Connection recovery | Auto-reconnect on NATS connection failure |
+| **NFR-203** | Connection recovery | Auto-reconnect on transport 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-302** | Transport security | TLS support for transport connections |
 | **NFR-303** | File server security | Authentication token for file uploads |
 
 ### 4.4 Observability & Telemetry
@@ -234,11 +229,11 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 
 | 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 |
-| Rust | Unlimited | Limited by NATS server configuration |
+| Desktop | Unlimited | Limited by transport server configuration |
+| Dart Desktop | Unlimited | Limited by transport server configuration |
+| Dart Flutter | Unlimited | Limited by transport server configuration |
+| Dart Web | Unlimited | Limited by transport server configuration |
+| Rust | Unlimited | Limited by transport server configuration |
 | MicroPython | 50KB | Hard limit due to 256KB-1MB memory |
 
 ---
@@ -252,7 +247,7 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 | `correlation_id` | String (UUID) | Track message flow across systems |
 | `msg_id` | String (UUID) | Unique message identifier |
 | `timestamp` | String (ISO 8601) | Message publication timestamp |
-| `send_to` | String | NATS subject to publish to |
+| `send_to` | String | Topic/subject to publish to |
 | `msg_purpose` | String | ACK, NACK, updateStatus, shutdown, chat |
 | `sender_name` | String | Sender application name |
 | `sender_id` | String (UUID) | Sender unique identifier |
@@ -260,7 +255,7 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 | `receiver_id` | String (UUID) | Receiver unique identifier (empty = broadcast) |
 | `reply_to` | String | Topic for reply messages |
 | `reply_to_msg_id` | String | Message ID being replied to |
-| `broker_url` | String | NATS server URL |
+| `broker_url` | String | Broker URL for the transport layer |
 | `metadata` | Dict | Message-level metadata |
 | `payloads` | Array | List of payload objects |
 
@@ -289,14 +284,14 @@ msghandler is a cross-platform, bi-directional data bridge that enables seamless
 | `Failed to upload` | File server error | Throw error |
 | `Failed to fetch` | File server unavailable | Retry with exponential backoff |
 | `Unknown transport` | Invalid transport type | Throw error |
-| `NATS connection failed` | NATS unavailable | Throw error |
+| `Transport connection failed` | Transport/broker unavailable | Throw error |
 
 ### 9.2 Exception Handling
 
 | Scenario | Handler |
 |----------|---------|
 | File server unavailable | Retry up to 5 times with exponential backoff |
-| NATS publish failure | Connection auto-reconnect |
+| Transport publish failure | Handled by caller |
 | Deserialization error | Log correlation ID and throw error |
 | Memory overflow (MicroPython) | Reject payloads >50KB |
 
@@ -350,7 +345,7 @@ function smartsend(
 )::Tuple{msg_envelope_v1, String} where {T1<:Any}
 ```
 
-**Note**: NATS publishing is the caller's responsibility. `smartsend` returns `(env::msg_envelope_v1, env_json_str::String)`.
+**Note**: Publishing via the transport layer is the caller's responsibility. `smartsend` returns `(env::msg_envelope_v1, env_json_str::String)`.
 
 ### 11.2 smartreceive Signature
 
@@ -364,7 +359,9 @@ function smartreceive(
 )::JSON.Object{String, Any}
 ```
 
-**Note**: Pass `String(nats_msg.payload)` from NATS subscription to `smartreceive`.
+**Note**: Pass the payload string from the transport subscription to `smartreceive`. The input is the JSON string payload from the transport message, not the transport message object directly.
+
+**Note**: Pass the payload from the transport subscription to `smartreceive`.
 
 ---
 
@@ -374,7 +371,7 @@ function smartreceive(
 
 | Component | Minimum | Notes |
 |-----------|---------|-------|
-| NATS Server | 1 instance | Single node for development |
+| Message Broker | 1 instance | Single node for development |
 | File Server | 1 instance | HTTP server for large payloads |
 | Client Memory | 50MB | Desktop platforms (Julia/JS/Python/Dart) |
 | Client Memory | 256KB | MicroPython devices |
@@ -383,7 +380,7 @@ function smartreceive(
 
 | Variable | Default | Description |
 |----------|---------|-------------|
-| `NATS_URL` | `nats://localhost:4222` | NATS server URL |
+| `BROKER_URL` | `ws://localhost:4222` | Message broker URL |
 | `FILESERVER_URL` | `http://localhost:8080` | HTTP file server URL |
 | `SIZE_THRESHOLD` | `500000` | Size threshold in bytes (0.5MB) |
 
@@ -409,6 +406,10 @@ function smartreceive(
 
 | Date | Version | Changes |
 |------|---------|---------|
+| 2026-05-15 | 1.3.0 | Made transport layer agnostic |
+| - | - | Removed all NATS-specific dependencies and references |
+| - | - | Updated all NATS references to generic "transport layer"/"message broker" |
+| - | - | Removed NATS client packages from dependencies tables |
 | 2026-05-13 | 1.2.0 | Aligned with ground truth implementation (src/msghandler.jl) |
 | - | - | Fixed smartsend signature: removed is_publish, NATS_connection; added sender_name |
 | - | - | Fixed smartreceive signature: takes msg_json_str::String instead of msg::NATS.Msg |
diff --git a/docs/specification.md b/docs/specification.md
index f3b2231..2b32c91 100644
--- a/docs/specification.md
+++ b/docs/specification.md
@@ -10,7 +10,7 @@
 
 ## 1. Technical Contract Overview
 
-This document defines the **technical contract** for msghandler - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, **Rust**, and **MicroPython** applications using NATS as the message bus.
+This document defines the **technical contract** for msghandler - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, **Rust**, and **MicroPython** applications using a message broker as the transport layer.
 
 This specification serves as the single source of truth for:
 - **Inputs**: What data structures are accepted by `smartsend()`
@@ -28,7 +28,7 @@ This specification serves as the single source of truth for:
 | 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 8 (Topic Convention) | FR-013, FR-014 | Topic/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 |
@@ -95,7 +95,7 @@ This specification serves as the single source of truth for:
 | `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 | FR-012, NFR-401 |
 | `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 | FR-013 |
+| `send_to` | `string` | Yes | Non-empty string | Topic/subject to publish the message to | FR-013 |
 | `msg_purpose` | `string` | Yes | Enum | Purpose of the message | FR-013 |
 | `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 | FR-013 |
@@ -103,7 +103,7 @@ This specification serves as the single source of truth for:
 | `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 | FR-013 |
 | `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 | FR-013 |
+| `broker_url` | `string` | Yes | Valid URL | Broker URL for the transport layer | FR-013 |
 | `metadata` | `object` | No | Any JSON object | Message-level metadata | NFR-401 |
 | `payloads` | `array` | Yes | Non-empty array | List of payload objects | FR-012, FR-013 |
 
@@ -240,7 +240,7 @@ await smartsend("/agent/v1/process", data)
 
 | Value | Description | Data Format | Use Case |
 |-------|-------------|-------------|----------|
-| `direct` | Payload sent directly via NATS | Base64-encoded string | Payloads < size_threshold |
+| `direct` | Payload sent directly via the transport layer | Base64-encoded string | Payloads < size_threshold |
 | `link` | Payload uploaded to file server | HTTP URL | Payloads ≥ size_threshold |
 
 ### `encoding` Enum
@@ -312,7 +312,7 @@ When `transport = "link"`, the `data` field contains a URL pointing to the uploa
 
 ---
 
-## NATS Subject Convention
+## Topic Convention
 
 ### Subject Naming Pattern
 
@@ -357,7 +357,7 @@ When `transport = "link"`, the `data` field contains a URL pointing to the uploa
 | `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 | FR-008, FR-009 |
 | `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 | FR-013, FR-014, NFR-201, NFR-203 |
+| `TRANSPORT_CONNECTION_FAILED` | 503 | Transport connection failed | Check broker/server availability | FR-013, FR-014, NFR-201, NFR-203 |
 | `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 | FR-003, FR-004, FR-005, NFR-104, NFR-105 |
 
@@ -366,7 +366,7 @@ When `transport = "link"`, the `data` field contains a URL pointing to the uploa
 | Scenario | Handler | Retry Policy | Requirement ID |
 |----------|---------|--------------|----------------|
 | 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 | FR-013, FR-014, NFR-201, NFR-203 |
+| Transport publish failure | Handled by caller | Caller's retry logic | FR-013, FR-014, NFR-201, NFR-203 |
 | 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) | FR-005, NFR-106 |
 
@@ -435,7 +435,7 @@ function smartsend(
 )::Tuple{msg_envelope_v1, String} where {T1<:Any}
 ```
 
-**Note**: NATS publishing is the caller's responsibility. Returns `(env::msg_envelope_v1, env_json_str::String)`.
+**Note**: Publishing via the transport layer is the caller's responsibility. Returns `(env::msg_envelope_v1, env_json_str::String)`.
 
 #### Python
 
@@ -443,7 +443,7 @@ function smartsend(
 async def smartsend(
     subject: str,
     data: List[Tuple[str, Any, str]],
-    broker_url: str = "nats://localhost:4222",
+    broker_url: str = DEFAULT_BROKER_URL,
     fileserver_url: str = "http://localhost:8080",
     fileserver_upload_handler: Callable = plik_oneshot_upload,
     size_threshold: int = 500_000,
@@ -459,7 +459,7 @@ async def smartsend(
 ) -> Tuple[Dict, str]:
 ```
 
-**Note**: NATS publishing is the caller's responsibility.
+**Note**: Publishing via the transport layer is the caller's responsibility.
 
 #### JavaScript (Node.js)
 
@@ -485,7 +485,7 @@ async function smartsend(
 ): Promise<[Object, string]>;
 ```
 
-**Note**: NATS publishing is the caller's responsibility.
+**Note**: Publishing via the transport layer is the caller's responsibility.
 
 #### JavaScript (Browser)
 
@@ -511,7 +511,7 @@ async function smartsend(
 ): Promise<[Object, string]>;
 ```
 
-**Note**: NATS publishing is the caller's responsibility.
+**Note**: Publishing via the transport layer is the caller's responsibility.
 
 #### MicroPython
 
@@ -524,7 +524,7 @@ def smartsend(
 ) -> Tuple[Dict, str]:
 ```
 
-**Note**: NATS publishing is the caller's responsibility.
+**Note**: Publishing via the transport layer is the caller's responsibility.
 
 #### Dart (Desktop/Flutter)
 
@@ -532,10 +532,10 @@ def smartsend(
 Future<[Map<String, dynamic>, String]> smartsend(
   String subject,
   List<List<dynamic>> data, {
-  String brokerUrl = 'nats://localhost:4222',
-  String fileserverUrl = 'http://localhost:8080',
+ String brokerUrl = DEFAULT_BROKER_URL,
+  String fileserverUrl = DEFAULT_FILESERVER_URL,
   Function? fileserverUploadHandler,
-  int sizeThreshold = 500000,
+  int sizeThreshold = DEFAULT_SIZE_THRESHOLD,
   String? correlationId,
   String msgPurpose = 'chat',
   String senderName = 'msghandler',
@@ -547,9 +547,8 @@ Future<[Map<String, dynamic>, String]> smartsend(
   String? senderId,
 }) async {
   // Returns [envelope, jsonString]
-  // NATS publishing is caller's responsibility
+  // Publishing via transport layer is caller's responsibility
 }
-```
 
 #### Dart Web
 
@@ -557,7 +556,7 @@ Future<[Map<String, dynamic>, String]> smartsend(
 Future<[Map<String, dynamic>, String]> smartsend(
   String subject,
   List<List<dynamic>> data, {
-  String brokerUrl = 'nats://localhost:4222',
+  String brokerUrl = DEFAULT_BROKER_URL,
   String fileserverUrl = 'http://localhost:8080',
   Function? fileserverUploadHandler,
   int sizeThreshold = 500000,
@@ -572,7 +571,7 @@ Future<[Map<String, dynamic>, String]> smartsend(
   String? senderId,
 }) async {
   // Returns [envelope, jsonString]
-  // NATS publishing is caller's responsibility
+  // Publishing via transport layer is caller's responsibility
 }
 ```
 
@@ -635,7 +634,7 @@ pub struct MsgEnvelopeV1 {
 }
 ```
 
-**Note**: NATS publishing is the caller's responsibility. Returns `Result<(MsgEnvelopeV1, String), msghandlerError>`. Uses `serde` for JSON serialization.
+**Note**: Publishing via the transport layer is the caller's responsibility. Returns `Result<(MsgEnvelopeV1, String), msghandlerError>`. Uses `serde` for JSON serialization.
 
 ### `smartreceive` Function Signature
 
@@ -643,7 +642,7 @@ pub struct MsgEnvelopeV1 {
 
 ```julia
 function smartreceive(
-    msg_json_str::String;  # Pass String(nats_msg.payload) from NATS subscription
+    msg_json_str::String;  # Pass payload from transport subscription
     fileserver_download_handler::Function = _fetch_with_backoff,
     max_retries::Int = 5,
     base_delay::Int = 100,
@@ -651,13 +650,13 @@ function smartreceive(
 )::JSON.Object{String, Any}
 ```
 
-**Note**: Input is JSON string from NATS message payload, not NATS.Msg directly.
+**Note**: Input is the JSON string payload from the transport subscription, not the transport message object directly.
 
 #### Python
 
 ```python
 async def smartreceive(
-    msg_json_str: str,  # JSON string from NATS message payload
+    msg_json_str: str,  # JSON string from transport message payload
     fileserver_download_handler: Callable = fetch_with_backoff,
     max_retries: int = 5,
     base_delay: int = 100,
@@ -665,13 +664,13 @@ async def smartreceive(
 ) -> Dict[str, Any]:
 ```
 
-**Note**: Input is JSON string from NATS message payload.
+**Note**: Input is the JSON string payload from the transport message.
 
 #### JavaScript (Node.js)
 
 ```typescript
 async function smartreceive(
-    msg_json_str: string,  // JSON string from NATS message payload
+    msg_json_str: string,  // JSON string from transport message payload
     options?: {
         fileserver_download_handler?: Function;
         max_retries?: number;
@@ -685,7 +684,7 @@ async function smartreceive(
 
 ```typescript
 async function smartreceive(
-    msg_json_str: string,  // JSON string from NATS message payload
+    msg_json_str: string,  // JSON string from transport message payload
     options?: {
         fileserver_download_handler?: Function;
         max_retries?: number;
@@ -695,7 +694,7 @@ async function smartreceive(
 ): Promise<Object>;
 ```
 
-**Note**: Input is JSON string from NATS message payload.
+**Note**: Input is the JSON string payload from the transport message.
 
 #### MicroPython
 
@@ -703,13 +702,13 @@ async function smartreceive(
 def smartreceive(msg_json_str: str, **kwargs) -> Dict[str, Any]:
 ```
 
-**Note**: Input is JSON string from NATS message payload.
+**Note**: Input is the JSON string payload from the transport message.
 
 #### Dart (Desktop/Flutter)
 
 ```dart
 Future<Map<String, dynamic>> smartreceive(
-  Map<String, dynamic> msg_json_str,  // JSON object from NATS message payload
+  Map<String, dynamic> msg_json_str,  // JSON object from transport message payload
   {
   Function? fileserverDownloadHandler,
   int maxRetries = 5,
@@ -724,7 +723,7 @@ Future<Map<String, dynamic>> smartreceive(
 
 ```dart
 Future<Map<String, dynamic>> smartreceive(
-  Map<String, dynamic> msg_json_str,  // JSON object from NATS message payload
+  Map<String, dynamic> msg_json_str,  // JSON object from transport message payload
   {
   Function? fileserverDownloadHandler,
   int maxRetries = 5,
@@ -739,7 +738,7 @@ Future<Map<String, dynamic>> smartreceive(
 
 ```rust
 pub async fn smartreceive(
-    msg_json_str: &str,  // JSON string from NATS message payload
+    msg_json_str: &str,  // JSON string from transport message payload
     options: &SmartreceiveOptions,
 ) -> Result<MsgEnvelopeV1, msghandlerError>
 
@@ -752,7 +751,7 @@ pub struct SmartreceiveOptions {
 }
 ```
 
-**Note**: Input is JSON string from NATS message payload. Returns `Result<MsgEnvelopeV1, msghandlerError>`.
+**Note**: Input is the JSON string payload from the transport message. Returns `Result<MsgEnvelopeV1, msghandlerError>`.
 
 ---
 
@@ -897,7 +896,7 @@ function fileserver_download_handler(
 |------|----------|----------|-------|
 | [`src/msghandler.jl`](../src/msghandler.jl) | Julia | Full feature set, Arrow IPC, multiple dispatch | Ground truth implementation |
 | [`src/msghandler_ssr.js`](../src/msghandler_ssr.js) | Node.js | Arrow IPC, async/await | Server-side JavaScript |
-| [`src/msghandler_csr.js`](../src/msghandler_csr.js) | Browser | JSON table only, WebSocket NATS | Client-side rendering |
+| [`src/msghandler_csr.js`](../src/msghandler_csr.js) | Browser | JSON table only | Client-side rendering |
 | [`src/msghandler.py`](../src/msghandler.py) | Python | Arrow IPC, async/await | Desktop Python |
 | [`src/msghandler.dart`](../src/msghandler.dart) | Dart | Full feature set, Arrow IPC, async/await | Desktop/Flutter/Web |
 | [`src/msghandler.rs`](../src/msghandler.rs) | Rust | Full feature set, Arrow IPC, async/await, type-safe | Uses tokio + serde + arrow2 |
@@ -910,7 +909,7 @@ The browser implementation ([`src/msghandler_csr.js`](../src/msghandler_csr.js))
 | 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 |
+| WebSocket 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
@@ -941,7 +940,7 @@ flowchart TD
     D --> F[Build envelope with metadata]
     E --> F
     F --> G[Convert envelope to JSON string]
-    G --> H[Publish to NATS subject]
+    G --> H[Publish to topic via transport]
     H --> I[Return envelope and JSON string to caller]
     
     style A fill:#f9f9f9,stroke:#333
@@ -954,7 +953,7 @@ flowchart TD
 
 ```mermaid
 flowchart TD
-    A[NATS message arrives] --> B[Parse JSON envelope]
+  A[Transport message arrives] --> B[Parse JSON envelope]
     B --> C[For each payload: Check transport type]
     C -->|transport == direct| D[Direct Transport: Extract Base64]
     C -->|transport == link| E[Link Transport: Fetch from URL]
@@ -1046,23 +1045,17 @@ flowchart TD
 
 | Platform | Package | Version | Purpose |
 |----------|---------|---------|---------|
-| Julia | NATS.jl | Latest | NATS client |
 | Julia | JSON.jl | Latest | JSON serialization |
 | 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 (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 |
+| Browser | - | - | Transport-agnostic (caller provides) |
 | 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) |
-| Rust | nats | Latest | NATS client |
 | Rust | serde | Latest | JSON serialization |
 | Rust | serde_json | Latest | JSON handling |
 | Rust | tokio | Latest | Async runtime |
@@ -1084,6 +1077,10 @@ flowchart TD
 
 | Date | Version | Changes |
 |------|---------|---------|
+| 2026-05-15 | 1.3.0 | Made transport layer agnostic |
+| - | - | Removed all NATS-specific dependencies (NATS.jl, nats, nats-py, nats.ws) |
+| - | - | Updated docs to reference generic message broker/transport |
+| - | - | broker_url is now metadata only, not used for active connections |
 | 2026-03-15 | 1.1.0 | Browser connection management |
 | - | - | Added NATSClient class with keepAlive support |
 | - | - | Added NATSConnectionPool for connection reuse |
@@ -1119,7 +1116,7 @@ flowchart TD
 |------|----------|----------|--------------------------|
 | [`src/msghandler.jl`](../src/msghandler.jl) | Julia | Full feature set, Arrow IPC, multiple dispatch | FR-001 through FR-014, NFR-101 through NFR-405 |
 | [`src/msghandler_ssr.js`](../src/msghandler_ssr.js) | Node.js | Arrow IPC, async/await | FR-001 through FR-014, NFR-101 through NFR-405 |
-| [`src/msghandler_csr.js`](../src/msghandler_csr.js) | Browser | JSON table only, WebSocket NATS | FR-001 through FR-014, NFR-101 through NFR-405 |
+| [`src/msghandler_csr.js`](../src/msghandler_csr.js) | Browser | JSON table only | FR-001 through FR-014, NFR-101 through NFR-405 |
 | [`src/msghandler.py`](../src/msghandler.py) | Python | Arrow IPC, async/await | FR-001 through FR-014, NFR-101 through NFR-405 |
 | [`src/msghandler.dart`](../src/msghandler.dart) | Dart | Full feature set, Arrow IPC, async/await | FR-001 through FR-014, NFR-101 through NFR-405 |
 | [`src/msghandler.rs`](../src/msghandler.rs) | Rust | Full feature set, Arrow IPC, async/await, type-safe | FR-001 through FR-014, NFR-101 through NFR-405 |
@@ -1129,23 +1126,17 @@ flowchart TD
 
 | 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 |
+| Browser | - | - | Transport-agnostic (caller provides) | FR-013, FR-014 |
 | Python | aiohttp | Latest | HTTP file server | FR-008, FR-009 |
 | Python | pyarrow | Latest | Arrow IPC support | FR-002, FR-012 |
-| Dart | nats | Latest | NATS client | FR-013, FR-014 |
 | Dart | http | Latest | HTTP file server | FR-008, FR-009 |
 | Dart | uuid | Latest | UUID generation | FR-011, NFR-401 |
 | Dart | dart-arrow | Latest | Arrow IPC support | FR-002, FR-012 |
-| Rust | nats | Latest | NATS client | FR-013, FR-014 |
 | Rust | serde | Latest | JSON serialization | FR-012, NFR-101, NFR-102 |
 | Rust | serde_json | Latest | JSON handling | FR-012, NFR-101, NFR-102 |
 | Rust | tokio | Latest | Async runtime | FR-013, FR-014 |
@@ -1160,6 +1151,10 @@ flowchart TD
 
 | Date | Version | Changes | Requirement ID(s) |
 |------|---------|---------|-------------------|
+| 2026-05-15 | 1.3.0 | Made transport layer agnostic | All |
+| - | - | Removed NATS-specific dependencies and references from all docs | All |
+| - | - | Updated all NATS references to generic "transport layer"/"message broker" | All |
+| - | - | Removed NATS client packages from dependencies tables | All |
 | 2026-05-13 | 1.2.0 | Aligned with ground truth implementation (src/msghandler.jl) | All |
 | - | - | Updated smartsend signatures: removed is_publish, nats_connection; added sender_name | FR-001 through FR-014 |
 | - | - | Updated smartreceive signatures: takes msg_json_str::String instead of msg | FR-001 through FR-014 |
@@ -1200,7 +1195,7 @@ flowchart TD
     "send_to": {
       "type": "string",
       "minLength": 1,
-      "description": "NATS subject to publish to"
+      "description": "Topic/subject to publish to"
     },
     "msg_purpose": {
       "type": "string",
@@ -1236,8 +1231,7 @@ flowchart TD
     },
     "broker_url": {
       "type": "string",
-      "pattern": "^nats://[^\\s]+$",
-      "description": "NATS broker URL"
+      "description": "Broker URL for the transport layer"
     },
     "metadata": {
       "type": "object",
@@ -1302,14 +1296,14 @@ flowchart TD
 }
 ```
 
-### B. AsyncAPI Specification (NATS)
+### B. AsyncAPI Specification
 
 ```yaml
 asyncapi: '2.6.0'
 info:
   title: msghandler API
   version: '1.0.0'
-  description: Cross-platform bi-directional data bridge using NATS
+  description: Cross-platform bi-directional data bridge using a message broker
   contact:
     name: msghandler Team
     url: https://github.com/your-org/msghandler
@@ -1331,12 +1325,12 @@ channels:
         schema:
           type: string
     publish:
-      summary: Publish message to NATS
+      summary: Publish message to transport
       operationId: publishMessage
       message:
         $ref: '#/components/message'
     subscribe:
-      summary: Subscribe to NATS messages
+      summary: Subscribe to messages from transport
       operationId: subscribeMessage
       message:
         $ref: '#/components/message'
diff --git a/docs/walkthrough.md b/docs/walkthrough.md
index 335fad8..a489997 100644
--- a/docs/walkthrough.md
+++ b/docs/walkthrough.md
@@ -9,7 +9,7 @@
 
 ## 1. Executive Summary
 
-This document provides the **end-to-end trace** for msghandler - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, **Rust**, and **MicroPython** applications using NATS as the message bus.
+This document provides the **end-to-end trace** for msghandler - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, **Dart**, **Rust**, and **MicroPython** applications using a message broker as the transport layer.
 
 This walkthrough serves as the primary onboarding guide for new developers and explains:
 - **User scenarios** - Real-world use cases from developer perspective
@@ -51,7 +51,7 @@ flowchart TB
             S3["Size Check"]
             S4["Transport Selection"]
             S5["Build Envelope"]
-            S6["Publish to NATS"]
+            S6["Publish to transport"]
             
             S1 --> S2
             S2 --> S3
@@ -62,7 +62,7 @@ flowchart TB
         
         subgraph Receiver["Receiver (smartreceive)"]
             direction LR
-            R1["Subscribe to NATS"]
+            R1["Subscribe via transport"]
             R2["Parse Envelope"]
             R3["Check Transport"]
             R4["Deserialize Data"]
@@ -99,7 +99,7 @@ flowchart TB
 
 | Principle | Description | Rationale |
 |-----------|-------------|-----------|
-| **Claim-Check Pattern** | Large payloads uploaded to HTTP server, URL sent via NATS | NATS has message size limits; avoids NATS overflow |
+| **Claim-Check Pattern** | Large payloads uploaded to HTTP server, URL sent via transport | Transport has message size limits; avoids overflow |
 | **Automatic Transport Selection** | Direct (< threshold) vs Link (≥ threshold) based on size | Optimizes memory vs network I/O trade-off |
 | **Cross-Platform API** | Consistent `smartsend()`/`smartreceive()` across all platforms | Simplifies developer experience |
 | **Exponential Backoff** | Retry downloads with increasing delays | Handles transient failures gracefully |
@@ -148,7 +148,7 @@ For each payload, msghandler determines transport:
 
 **Rationale**:
 - Direct transport is faster for small payloads (no file server round-trip)
-- Link transport is used when payload ≥ 0.5MB (avoids NATS size limits)
+- Link transport is used when payload ≥ 0.5MB (avoids transport size limits)
 
 #### Step 3: Serialization and Encoding
 
@@ -213,25 +213,26 @@ msghandler builds the message envelope:
 - **reply_to**: Tells backend where to send response
 - **payloads array**: Contains all data with metadata for proper handling
 
-#### Step 5: Publish to NATS (Caller's Responsibility)
+#### Step 5: Publish to Transport (Caller's Responsibility)
 
 ```javascript
-// NATS publishing is the caller's responsibility
-const conn = await NATS.connect({ servers: "ws://localhost:4222" });
-await conn.publish("/agent/wine/api/v1/prompt", msgJson);
+// Publishing via the transport layer is the caller's responsibility
+// Example with any transport (NATS, MQTT, WebSocket, etc.)
+// const conn = await transportClient.connect({ servers: "ws://localhost:4222" });
+// await conn.publish("/agent/wine/api/v1/prompt", msgJson);
 ```
 
 **Rationale**:
-- NATS provides low-latency message delivery
+- The transport layer provides message delivery (NATS, MQTT, WebSocket, etc.)
 - JSON format ensures cross-platform compatibility
-- `smartsend()` returns `(env, msgJson)` - caller handles publishing
+- `smartsend()` returns `(env, msgJson)` - caller handles publishing via their chosen transport
 
 #### Step 6: Julia Backend Receives Message
 
 ```julia
 # Julia backend
-nats_msg = NATS.subscription.next()  # Get message from NATS
-env = smartreceive(String(nats_msg.payload))
+transport_msg = transport_subscription.next()  # Get message from transport
+env = smartreceive(String(transport_msg.payload))
 
 # env["payloads"] is now:
 # [
@@ -302,7 +303,7 @@ const [env, msgJson] = await msghandler.smartsend(
 **Rationale**:
 - Link transport used for large payloads
 - File server handles large file upload
-- NATS only sends URL (small message)
+- Transport only sends URL (small message)
 
 #### Step 3: File Server Upload
 
@@ -356,8 +357,8 @@ const response = await plikOneshotUpload(
 
 ```julia
 # Julia backend
-nats_msg = NATS.subscription.next()
-env = smartreceive(String(nats_msg.payload))
+transport_msg = transport_subscription.next()
+env = smartreceive(String(transport_msg.payload))
 
 # msghandler automatically:
 # 1. Extracts URL from payload
@@ -396,7 +397,7 @@ df = pd.DataFrame({
 env, msg_json = await smartsend(
     "/agent/wine/api/v1/analyze",
     [("data", df, "arrowtable")],
-    broker_url="nats://localhost:4222",
+    broker_url=DEFAULT_BROKER_URL,
     receiver_name="agent-backend"
 )
 ```
@@ -429,8 +430,8 @@ arrow_bytes = buf.getvalue()
 
 ```julia
 # Julia backend
-nats_msg = NATS.subscription.next()
-env = smartreceive(String(nats_msg.payload))
+transport_msg = transport_subscription.next()
+env = smartreceive(String(transport_msg.payload))
 
 # env["payloads"][1] is now:
 # ("data", DataFrame with id, name, score columns, "arrowtable")
@@ -479,7 +480,7 @@ use base64::{Engine as _, engine::general_purpose::STANDARD as BASE64};
 
 #[tokio::main]
 async fn main() {
-    let conn = nats::connect("nats://localhost:4222").unwrap();
+    let conn = transport_client::connect("ws://localhost:4222").unwrap();
     
     // Subscribe and receive messages
     let mut sub = conn.subscribe("/agent/wine/api/v1/analyze").unwrap();
@@ -520,7 +521,7 @@ async fn main() {
 
 **Rationale**:
 - **serde serialization**: Automatic JSON deserialization to `MsgEnvelopeV1`
-- **tokio runtime**: Efficient async I/O for NATS and HTTP operations
+- **tokio runtime**: Efficient async I/O for transport and HTTP operations
 - **smartreceive deserialization**: Payload data is deserialized and stored as strings in `payload.data`
 - **Type dispatch**: `payload_type` field determines how to interpret the `data` string
 
@@ -548,14 +549,14 @@ let (envelope, json_str) = smartsend(
         ),
     ],
     &SmartsendOptions {
-        broker_url: "nats://localhost:4222".to_string(),
+        broker_url: DEFAULT_BROKER_URL.to_string(),
         reply_to: "/python/worker/v1/results".to_string(),
         msg_purpose: "chat".to_string(),
         ..Default::default()
     },
 ).await?;
 
-// Caller publishes to NATS
+// Caller publishes via transport
 conn.publish("/agent/wine/api/v1/results", &json_str)?;
 ```
 
@@ -569,7 +570,7 @@ conn.publish("/agent/wine/api/v1/results", &json_str)?;
 
 ```python
 # Python backend receives Rust response
-env = await smartreceive(str(nats_msg.payload))
+env = await smartreceive(str(transport_msg.payload))
 
 # env["payloads"][0] is now:
 # ("results", arrow_table_data, "arrowtable")
@@ -598,9 +599,9 @@ let (envelope, json_str) = smartsend(
         ),
     ],
     &SmartsendOptions {
-        broker_url: "nats://localhost:4222".to_string(),
-        fileserver_url: "http://localhost:8080".to_string(),
-        size_threshold: 500_000,  // 0.5MB triggers link transport
+        broker_url: DEFAULT_BROKER_URL.to_string(),
+        fileserver_url: DEFAULT_FILESERVER_URL.to_string(),
+        size_threshold: DEFAULT_SIZE_THRESHOLD,  // threshold triggers link transport
         ..Default::default()
     },
 ).await?;
@@ -637,7 +638,7 @@ sensor_data = {
 env, msg_json = smartsend(
     "/sensor/device/v1/readings",
     [("data", sensor_data, "dictionary")],
-    broker_url="nats://localhost:4222",
+    broker_url=DEFAULT_BROKER_URL,
     size_threshold=100000  # 100KB for MicroPython
 )
 ```
@@ -658,15 +659,15 @@ payload_b64 = base64.b64encode(json_bytes).decode('ascii')
 
 **Rationale**:
 - JSON format for human-readable data
-- Base64 for NATS compatibility
+- Base64 for transport compatibility
 - UTF-8 for text encoding
 
 #### Step 3: Python Backend Receives
 
 ```python
 # Python backend
-nats_msg = await nats_consumer.next()
-env = await smartreceive(str(nats_msg.payload))
+transport_msg = await transport_consumer.next()
+env = await smartreceive(str(transport_msg.payload))
 
 # env["payloads"][0] is now:
 # ("data", {"temperature": 25.5, "humidity": 60.0, ...}, "dictionary")
@@ -708,14 +709,14 @@ const [env, msgJson] = await msghandler.smartsend(
 **Rationale**:
 - Empty `receiver_name` = broadcast to all subscribers
 - Chat messages often include text + images
-- NATS wildcard subscriptions route to correct recipients
+- Transport wildcard subscriptions route to correct recipients
 
 #### Step 2: Python Backend Receives
 
 ```python
 # Python (Backend)
-nats_msg = await nats_consumer.next()
-env = await smartreceive(str(nats_msg.payload))
+transport_msg = await transport_consumer.next()
+env = await smartreceive(str(transport_msg.payload))
 
 # env["payloads"] is now:
 # [
@@ -733,8 +734,8 @@ env = await smartreceive(str(nats_msg.payload))
 
 ```julia
 # Julia (Backend)
-nats_msg = NATS.subscription.next()
-env = smartreceive(String(nats_msg.payload))
+transport_msg = transport_subscription.next()
+env = smartreceive(String(transport_msg.payload))
 
 # env["payloads"] is now:
 # [
@@ -795,7 +796,7 @@ await msghandler.smartsend(
 | File server unavailable | `UPLOAD_FAILED` | Fall back to direct transport or smaller payloads |
 | File server download fails | `DOWNLOAD_FAILED` | Retry with exponential backoff |
 | Payload type mismatch | `DESERIALIZATION_ERROR` | Validate payload_type matches data |
-| NATS connection lost | `NATS_CONNECTION_FAILED` | NATS client auto-reconnects |
+| Transport connection lost | `TRANSPORT_CONNECTION_FAILED` | Transport client auto-reconnects |
 
 ### Error Response Format
 
@@ -828,14 +829,14 @@ correlation_id = string(uuid4())
 # Use throughout the flow
 log_trace(correlation_id, "Starting smartsend")
 log_trace(correlation_id, "Serialized payload size: 100 bytes")
-log_trace(correlation_id, "Published to NATS")
+log_trace(correlation_id, "Published to transport")
 ```
 
 **Log Format**:
 ```
 [2026-03-13T16:30:00.000Z] [Correlation: abc123...] Starting smartsend
 [2026-03-13T16:30:00.001Z] [Correlation: abc123...] Serialized payload size: 100 bytes
-[2026-03-13T16:30:00.002Z] [Correlation: abc123...] Published to NATS
+[2026-03-13T16:30:00.002Z] [Correlation: abc123...] Published to transport
 ```
 
 ---
@@ -846,7 +847,7 @@ log_trace(correlation_id, "Published to NATS")
 
 | Strategy | Description | When to Use |
 |----------|-------------|-------------|
-| Pre-create NATS connection | Reuse connection for multiple sends | High-throughput scenarios |
+| Pre-create transport connection | Reuse connection for multiple sends | High-throughput scenarios |
 | Adjust size threshold | Increase threshold if file server slow | File server bottleneck |
 | Use direct transport | Avoid file server for small payloads | Low latency requirements |
 
@@ -868,7 +869,7 @@ log_trace(correlation_id, "Published to NATS")
 
 | Component | Minimum | Notes |
 |-----------|---------|-------|
-| NATS Server | 1 instance | Single node for development |
+| Message Broker | 1 instance | Single node for development |
 | File Server | 1 instance | HTTP server for large payloads |
 | Client Memory | 50MB | Desktop platforms (Julia/JS/Python/Dart) |
 | Client Memory | 256KB | MicroPython devices |
@@ -877,7 +878,7 @@ log_trace(correlation_id, "Published to NATS")
 
 | Variable | Default | Description |
 |----------|---------|-------------|
-| `NATS_URL` | `nats://localhost:4222` | NATS server URL |
+| `BROKER_URL` | `ws://localhost:4222` | Message broker URL |
 | `FILESERVER_URL` | `http://localhost:8080` | HTTP file server URL |
 | `SIZE_THRESHOLD` | `500000` | Size threshold in bytes (0.5MB) |
 
@@ -911,7 +912,7 @@ log_trace(correlation_id, "Published to NATS")
 |------|----------|----------|---------------------------|
 | [`src/msghandler.jl`](../src/msghandler.jl) | Julia | Full feature set, Arrow IPC, multiple dispatch | specification.md:2-19 (all sections) |
 | [`src/msghandler_ssr.js`](../src/msghandler_ssr.js) | Node.js | Arrow IPC, async/await | specification.md:2-19 (all sections) |
-| [`src/msghandler_csr.js`](../src/msghandler_csr.js) | Browser | JSON table only, WebSocket NATS | specification.md:2-19 (all sections) |
+| [`src/msghandler_csr.js`](../src/msghandler_csr.js) | Browser | JSON table only | specification.md:2-19 (all sections) |
 | [`src/msghandler.py`](../src/msghandler.py) | Python | Arrow IPC, async/await | specification.md:2-19 (all sections) |
 | [`src/msghandler.dart`](../src/msghandler.dart) | Dart | Full feature set, Arrow IPC, async/await | specification.md:2-19 (all sections) |
 | [`src/msghandler.rs`](../src/msghandler.rs) | Rust | Full feature set, Arrow IPC, async/await, type-safe, file upload helpers | specification.md:2-19 (all sections) |
@@ -923,6 +924,10 @@ log_trace(correlation_id, "Published to NATS")
 
 | Date | Version | Changes | Specification Reference |
 |------|---------|---------|------------------------|
+| 2026-05-15 | 1.5.0 | Made transport layer agnostic | All sections |
+| - | - | Removed all NATS-specific references from walkthrough | All sections |
+| - | - | Updated code examples to use transport-agnostic patterns | All sections |
+| - | - | Updated diagrams to remove NATS-specific labels | All sections |
 | 2026-05-14 | 1.4.0 | Updated Rust API to reflect `smartreceive` deserialization changes | All sections |
 | - | - | `smartreceive` now stores deserialized data in `MsgPayloadV1.data` | specification.md:8 |
 | - | - | Added `plik_upload_file` convenience function documentation | specification.md:13 |
@@ -932,8 +937,8 @@ log_trace(correlation_id, "Published to NATS")
 | - | - | Added Rust user scenario (User Scenario 4) | specification.md:11 (Rust API) |
 | - | - | Updated scenario numbering (MicroPython → Scenario 5, Cross-Platform → Scenario 6) | All sections |
 | 2026-05-13 | 1.2.0 | Aligned with ground truth implementation (src/msghandler.jl) | All sections |
-| - | - | Updated smartreceive calls to use String(nats_msg.payload) pattern | All sections |
-| - | - | Removed NATSClient.publish() calls (caller responsible for NATS publishing) | All sections |
+| - | - | Updated smartreceive calls to use transport payload pattern | All sections |
+| - | - | Removed NATSClient.publish() calls (caller responsible for transport publishing) | All sections |
 | - | - | Removed is_publish and nats_connection parameter references | All sections |
 | 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) |