diff --git a/backends/mizan-django/src/mizan/channels/connection.py b/backends/mizan-django/src/mizan/channels/connection.py
index 2d2a59d..29f7bc4 100644
--- a/backends/mizan-django/src/mizan/channels/connection.py
+++ b/backends/mizan-django/src/mizan/channels/connection.py
@@ -18,7 +18,7 @@ Protocol:
         {"channel": "chat", "params": {"room": "general"}, "type": "DjangoMessage", "data": {...}}
 
         # RPC responses
-        {"id": "request-id", "ok": true, "data": {...}}
+        {"id": "request-id", "ok": true, "data": {"result": {...}, "invalidate": [...]}}
         {"id": "request-id", "ok": false, "error": {...}}
 
         {"error": "..."}
@@ -390,7 +390,7 @@ class DjangoReactConsumer(AsyncJsonWebsocketConsumer):
 
         Protocol:
             Request:  {"action": "rpc", "id": "request-id", "fn": "function_name", "args": {...}}
-            Response: {"id": "request-id", "ok": true, "data": {...}}
+            Response: {"id": "request-id", "ok": true, "data": {"result":..., "invalidate":[...]}}
                   or: {"id": "request-id", "ok": false, "error": {...}}
 
         Security:
@@ -485,13 +485,23 @@ class DjangoReactConsumer(AsyncJsonWebsocketConsumer):
                 }
             )
         else:
-            await self.send_json(
-                {
-                    "id": request_id,
-                    "ok": True,
-                    "data": result.data,
-                }
+            # the same {result, invalidate, merge} envelope the HTTP RPC path builds, so a
+            # mutation sent over the socket invalidates exactly as one sent over HTTP
+            from mizan.client.executor import _resolve_invalidation, _resolve_merges
+
+            data = {"result": result.data}
+            invalidate = await sync_to_async(_resolve_invalidation, thread_sensitive=True)(
+                fn_class, args
             )
+            merges = await sync_to_async(_resolve_merges, thread_sensitive=True)(
+                fn_class, args, result.data
+            )
+            if invalidate:
+                data["invalidate"] = invalidate
+            if merges:
+                data["merge"] = merges
+
+            await self.send_json({"id": request_id, "ok": True, "data": data})
 
     async def channel_message(self, event: dict):
         """
diff --git a/backends/mizan-django/src/mizan/tests/test_channels.py b/backends/mizan-django/src/mizan/tests/test_channels.py
index 7f89f31..5d305b9 100644
--- a/backends/mizan-django/src/mizan/tests/test_channels.py
+++ b/backends/mizan-django/src/mizan/tests/test_channels.py
@@ -1000,7 +1000,8 @@ class WebSocketRPCTests(TestCase):
 
         self.assertEqual(response["id"], "test-123")
         self.assertTrue(response["ok"])
-        self.assertEqual(response["data"]["echo"], "Echo: Hello")
+        # data is the {result, invalidate, merge} envelope, as on the HTTP RPC path
+        self.assertEqual(response["data"]["result"]["echo"], "Echo: Hello")
 
     def test_handle_rpc_with_multiple_args(self):
         """_handle_rpc should handle functions with multiple arguments."""
@@ -1029,7 +1030,7 @@ class WebSocketRPCTests(TestCase):
 
         response = consumer.sent_messages[0]
         self.assertTrue(response["ok"])
-        self.assertEqual(response["data"]["result"], 8)
+        self.assertEqual(response["data"]["result"]["result"], 8)
 
     def test_handle_rpc_function_not_found(self):
         """_handle_rpc should return error for unknown function."""
diff --git a/backends/mizan-fastapi/src/mizan_fastapi/websocket.py b/backends/mizan-fastapi/src/mizan_fastapi/websocket.py
index 412e860..3ff0f8b 100644
--- a/backends/mizan-fastapi/src/mizan_fastapi/websocket.py
+++ b/backends/mizan-fastapi/src/mizan_fastapi/websocket.py
@@ -6,6 +6,7 @@ The WebSocket endpoint — channel subscriptions and RPC over one connection.
         {"action": "unsubscribe", "channel": "chat", "params": {...}}
         {"action": "message",     "channel": "chat", "params": {...}, "data": {...}}
         {"action": "rpc", "id": "request-id", "fn": "function_name", "args": {...}}
+        {"action": "ctx", "id": "request-id", "context": "name", "params": {...}}
 
     Server sends:
         {"channel": "chat", "params": {...}, "type": "...", "data": {...}}
@@ -29,7 +30,7 @@ from typing import Any
 
 from fastapi import APIRouter, WebSocket, WebSocketDisconnect
 
-from mizan_core.registry import get_function
+from mizan_core.registry import get_context_groups, get_function
 from mizan_fastapi import channels
 from mizan_fastapi.executor import (
     MizanError,
@@ -162,11 +163,41 @@ async def _rpc(socket: WebSocket, body: dict[str, Any]) -> None:
     await socket.send_json({"id": request_id, "ok": True, "data": data})
 
 
+async def _ctx(socket: WebSocket, body: dict[str, Any]) -> None:
+    """A context bundle over the socket, so a client needs no second connection to read."""
+    request_id = body.get("id")
+    name = body.get("context") or ""
+    fn_names = get_context_groups().get(name)
+    if not fn_names:
+        await socket.send_json(
+            {
+                "id": request_id,
+                "ok": False,
+                "error": {"code": "NOT_FOUND", "message": f"Context '{name}' not found"},
+            }
+        )
+        return
+
+    params = body.get("params") or {}
+    request = _SocketRequest(socket)
+    try:
+        bundled = {fn: await execute_function(request, fn, params) for fn in fn_names}
+    except MizanError as e:
+        payload: dict[str, Any] = {"code": e.code.value, "message": e.message}
+        if e.details:
+            payload["details"] = e.details
+        await socket.send_json({"id": request_id, "ok": False, "error": payload})
+        return
+
+    await socket.send_json({"id": request_id, "ok": True, "data": bundled})
+
+
 _ACTIONS = {
     "subscribe": _subscribe,
     "unsubscribe": _unsubscribe,
     "message": _message,
     "rpc": _rpc,
+    "ctx": _ctx,
 }
 
 
diff --git a/frontends/mizan-ws-transport/package.json b/frontends/mizan-ws-transport/package.json
new file mode 100644
index 0000000..7842c44
--- /dev/null
+++ b/frontends/mizan-ws-transport/package.json
@@ -0,0 +1,14 @@
+{
+  "name": "@mizan/ws-transport",
+  "version": "0.1.0",
+  "description": "Mizan transport carrying RPC, context bundles and channel subscriptions over one WebSocket.",
+  "type": "module",
+  "main": "src/index.ts",
+  "exports": {
+    ".": "./src/index.ts"
+  },
+  "peerDependencies": {
+    "@mizan/base": "*"
+  },
+  "license": "Elastic-2.0"
+}
diff --git a/frontends/mizan-ws-transport/src/index.ts b/frontends/mizan-ws-transport/src/index.ts
new file mode 100644
index 0000000..f4a19f9
--- /dev/null
+++ b/frontends/mizan-ws-transport/src/index.ts
@@ -0,0 +1,227 @@
+/**
+ * `@mizan/ws-transport` — RPC, context bundles and channel subscriptions over one socket.
+ *
+ * The same connection carries every direction of traffic, so an app opens one and needs
+ * no HTTP fallback for reads:
+ *
+ *     browser -> server
+ *       { action: 'rpc', id, fn, args }
+ *       { action: 'ctx', id, context, params }
+ *       { action: 'subscribe' | 'unsubscribe', channel, params }
+ *       { action: 'message', channel, params, data }
+ *
+ *     server -> browser
+ *       { id, ok: true,  data }                      // correlated reply
+ *       { id, ok: false, error: { code, message } }
+ *       { channel, params, type, data }              // a channel push, uncorrelated
+ *
+ * `call` resolves to the `{result, invalidate, merge}` envelope, which is what `mizanCall`
+ * reads to apply server-driven invalidation — so a mutation sent over the socket
+ * invalidates exactly as one sent over HTTP.
+ */
+
+import type { MizanTransport } from '@mizan/base'
+
+type Pending = { resolve: (v: any) => void; reject: (e: any) => void }
+
+export class MizanSocketError extends Error {
+    code: string
+    details?: unknown
+
+    constructor(code: string, message: string, details?: unknown) {
+        super(message)
+        this.name = 'MizanSocketError'
+        this.code = code
+        this.details = details
+    }
+}
+
+/** A push from a channel, delivered to every handler subscribed to it. */
+export type ChannelMessage = {
+    channel: string
+    params: Record<string, any>
+    type: string
+    data: any
+}
+
+export type ChannelHandler = (msg: ChannelMessage) => void
+
+export type WsTransportOptions = {
+    /** Milliseconds between reconnect attempts. 0 disables reconnection. */
+    retryMs?: number
+    /** A reply that never arrives rejects after this many milliseconds. 0 disables. */
+    timeoutMs?: number
+}
+
+export class MizanSocket {
+    private url: string
+    private socket: WebSocket | null = null
+    private pending = new Map<string, Pending>()
+    private handlers = new Map<string, Set<ChannelHandler>>()
+    // re-sent on every open, so a subscription survives a reconnect
+    private subscriptions = new Map<string, { channel: string; params?: Record<string, any> }>()
+    private opening: Promise<void> | null = null
+    private seq = 0
+    private retryMs: number
+    private timeoutMs: number
+
+    constructor(url: string, opts: WsTransportOptions = {}) {
+        this.url = url
+        this.retryMs = opts.retryMs ?? 1000
+        this.timeoutMs = opts.timeoutMs ?? 30000
+    }
+
+    private key(channel: string, params?: Record<string, any>): string {
+        const parts = Object.entries(params ?? {})
+            .map(([k, v]) => `${k}=${v}`)
+            .sort()
+        return parts.length ? `${channel}:${parts.join(':')}` : channel
+    }
+
+    /** The open socket, connecting if needed. Concurrent callers share one attempt. */
+    private connect(): Promise<void> {
+        if (this.socket && this.socket.readyState === WebSocket.OPEN) return Promise.resolve()
+        if (this.opening) return this.opening
+
+        this.opening = new Promise<void>((resolve, reject) => {
+            const socket = new WebSocket(this.url)
+            this.socket = socket
+
+            socket.onopen = () => {
+                this.opening = null
+                for (const sub of this.subscriptions.values()) {
+                    socket.send(JSON.stringify({ action: 'subscribe', ...sub }))
+                }
+                resolve()
+            }
+            socket.onmessage = (ev) => this.receive(ev.data)
+            socket.onerror = () => {
+                this.opening = null
+                reject(new MizanSocketError('TRANSPORT', `websocket error on ${this.url}`))
+            }
+            socket.onclose = () => {
+                this.opening = null
+                this.socket = null
+                // an in-flight call cannot be answered by a socket that is gone
+                for (const [, p] of this.pending) {
+                    p.reject(new MizanSocketError('TRANSPORT', 'socket closed before reply'))
+                }
+                this.pending.clear()
+                if (this.retryMs > 0 && this.handlers.size > 0) this.retry()
+            }
+        })
+        return this.opening
+    }
+
+    /** Reconnect for the subscriptions still held. A failed attempt is reported and retried. */
+    private retry(): void {
+        setTimeout(() => {
+            this.connect().catch((e) => {
+                console.error(`mizan socket: reconnect to ${this.url} failed`, e)
+                if (this.retryMs > 0 && this.handlers.size > 0) this.retry()
+            })
+        }, this.retryMs)
+    }
+
+    private receive(raw: string): void {
+        const msg = JSON.parse(raw)
+
+        if (msg.id !== undefined && this.pending.has(msg.id)) {
+            const p = this.pending.get(msg.id)!
+            this.pending.delete(msg.id)
+            if (msg.ok) p.resolve(msg.data)
+            else
+                p.reject(
+                    new MizanSocketError(
+                        msg.error?.code ?? 'INTERNAL_ERROR',
+                        msg.error?.message ?? 'call failed',
+                        msg.error?.details,
+                    ),
+                )
+            return
+        }
+
+        if (msg.channel !== undefined) {
+            const handlers = this.handlers.get(this.key(msg.channel, msg.params))
+            if (handlers) for (const h of handlers) h(msg as ChannelMessage)
+            return
+        }
+
+        // an error with no id belongs to no call — surface it rather than drop it
+        if (msg.error !== undefined) console.error('mizan socket:', msg.error)
+    }
+
+    /** Send an action expecting a correlated reply. */
+    private async request(action: string, body: Record<string, any>): Promise<any> {
+        await this.connect()
+        const id = String(++this.seq)
+        return new Promise((resolve, reject) => {
+            this.pending.set(id, { resolve, reject })
+            if (this.timeoutMs > 0) {
+                setTimeout(() => {
+                    if (this.pending.delete(id)) {
+                        reject(new MizanSocketError('TIMEOUT', `${action} ${id} had no reply`))
+                    }
+                }, this.timeoutMs)
+            }
+            this.socket!.send(JSON.stringify({ action, id, ...body }))
+        })
+    }
+
+    /** Join a channel. The returned function leaves it. */
+    async subscribe(
+        channel: string,
+        params: Record<string, any> | undefined,
+        handler: ChannelHandler,
+    ): Promise<() => void> {
+        const key = this.key(channel, params)
+        const first = !this.handlers.has(key)
+        if (first) this.handlers.set(key, new Set())
+        this.handlers.get(key)!.add(handler)
+
+        await this.connect()
+        if (first) {
+            this.subscriptions.set(key, { channel, params })
+            this.socket!.send(JSON.stringify({ action: 'subscribe', channel, params }))
+        }
+
+        return () => {
+            const set = this.handlers.get(key)
+            if (!set) return
+            set.delete(handler)
+            if (set.size > 0) return
+            this.handlers.delete(key)
+            this.subscriptions.delete(key)
+            if (this.socket?.readyState === WebSocket.OPEN) {
+                this.socket.send(JSON.stringify({ action: 'unsubscribe', channel, params }))
+            }
+        }
+    }
+
+    /** Send into a channel. Whether it reaches the group is the channel's decision. */
+    async send(channel: string, params: Record<string, any> | undefined, data: any): Promise<void> {
+        await this.connect()
+        this.socket!.send(JSON.stringify({ action: 'message', channel, params, data }))
+    }
+
+    close(): void {
+        this.retryMs = 0
+        this.socket?.close()
+    }
+
+    transport(): MizanTransport {
+        return {
+            call: (fn, args) => this.request('rpc', { fn, args }),
+            fetch: (context, params) => this.request('ctx', { context, params }),
+        }
+    }
+}
+
+/** The transport, plus the socket it rides, so channels are reachable from the same object. */
+export function wsTransport(
+    url: string,
+    opts: WsTransportOptions = {},
+): { transport: MizanTransport; socket: MizanSocket } {
+    const socket = new MizanSocket(url, opts)
+    return { transport: socket.transport(), socket }
+}