Flatten to three packages + extract mizan-runtime

packages/
  mizan-runtime/   Framework-agnostic state engine (~150 lines)
                   Context registry, batched invalidation, fetch primitives
  mizan-django/    Django server adapter (was packages/mizan-rpc/adapters/django/)
                   Codegen moved to mizan-django/generate/
  mizan-react/     React adapter (was packages/mizan-csr/adapters/react/)

Removed premature abstractions: mizan-ast, mizan-schema, mizan-rpc,
mizan-csr, mizan-ssr stub packages. The actual architecture is three
concrete packages, not five abstract layers.

mizan-runtime implements the v1 spec: registerContext with params,
scoped invalidation via microtask batching, server-driven invalidation
from mutation responses, mizanFetch for context bundles, mizanCall for
mutations.

264 Django + 33 React tests pass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/mizan-react/src/channels/context.tsx

@@ -0,0 +1,102 @@
+'use client'
+
+/**
+ * React context for mizan/channels
+ */
+
+import { createContext, useContext, useEffect, useMemo, useRef, useState, type ReactNode } from 'react'
+import { ChannelConnection, type ChannelConnectionOptions } from './connection'
+import type { ConnectionStatus } from './types'
+
+interface ChannelContextValue {
+    connection: ChannelConnection
+    status: ConnectionStatus
+}
+
+const ChannelContext = createContext<ChannelContextValue | null>(null)
+
+export interface ChannelProviderProps {
+    children: ReactNode
+
+    /** WebSocket URL (default: /ws/) */
+    url?: string
+
+    /** Reconnect on disconnect (default: true) */
+    reconnect?: boolean
+
+    /** Reconnection delay in ms (default: 1000) */
+    reconnectDelay?: number
+
+    /** Maximum reconnection attempts (default: 10) */
+    maxReconnectAttempts?: number
+
+    /** Connect automatically on mount (default: true) */
+    autoConnect?: boolean
+
+    /** Custom connection instance (for testing) */
+    connection?: ChannelConnection
+}
+
+export function ChannelProvider({
+    children,
+    url,
+    reconnect,
+    reconnectDelay,
+    maxReconnectAttempts,
+    autoConnect = true,
+    connection: providedConnection,
+}: ChannelProviderProps) {
+    const connectionRef = useRef<ChannelConnection | null>(null)
+
+    // Use provided connection or create one
+    if (!connectionRef.current) {
+        connectionRef.current = providedConnection ?? new ChannelConnection({
+            url,
+            reconnect,
+            reconnectDelay,
+            maxReconnectAttempts,
+        })
+    }
+
+    const connection = connectionRef.current
+
+    // Track status for context value
+    const [status, setStatus] = useState<ConnectionStatus>(connection.status)
+
+    useEffect(() => {
+        const unsubscribe = connection.onStatusChange(setStatus)
+
+        if (autoConnect) {
+            connection.connect()
+        }
+
+        return () => {
+            unsubscribe()
+            connection.disconnect()
+        }
+    }, [connection, autoConnect])
+
+    const value = useMemo(() => ({
+        connection,
+        status,
+    }), [connection, status])
+
+    return (
+        <ChannelContext value={value}>
+            {children}
+        </ChannelContext>
+    )
+}
+
+export function useChannelContext(): ChannelContextValue {
+    const context = useContext(ChannelContext)
+    if (!context) {
+        throw new Error('useChannelContext must be used within a ChannelProvider')
+    }
+    return context
+}
+
+export function useChannelStatus(): ConnectionStatus {
+    const { status } = useChannelContext()
+    return status
+}