diff --git a/.changeset/sse-solid2-async-reactivity.md b/.changeset/sse-solid2-async-reactivity.md
new file mode 100644
index 000000000..9c23f83f2
--- /dev/null
+++ b/.changeset/sse-solid2-async-reactivity.md
@@ -0,0 +1,68 @@
+---
+"@solid-primitives/sse": minor
+---
+
+Align `createSSE` with Solid 2.0 async reactivity patterns
+
+### Breaking changes
+
+**`pending` removed from `SSEReturn`**
+
+Use `<Loading>` for initial load UI and `isPending(() => data())` for stale-while-revalidating. Both are re-exported from this package.
+
+```tsx
+// Before
+const { data, pending } = createSSE(url);
+<Show when={!pending()}><p>{data()}</p></Show>
+
+// After — declarative initial load
+<Loading fallback={<p>Connecting…</p>}>
+  <p>{data()}</p>
+</Loading>
+
+// After — stale-while-revalidating (only true once a value exists and new data is pending)
+<Show when={isPending(() => data())}><p>Refreshing…</p></Show>
+```
+
+**`error` removed from `SSEReturn`**
+
+Terminal errors (connection CLOSED with no retries left) now propagate through `data()` to `<Errored>`. Non-terminal errors (browser reconnecting) are still surfaced via `onError` callback.
+
+```tsx
+// Before
+const { data, error } = createSSE(url);
+<Show when={error()}><p>Error: {error()?.type}</p></Show>
+
+// After — single error path via Errored boundary
+<Errored fallback={err => <p>Connection failed</p>}>
+  <Loading fallback={<p>Connecting…</p>}>
+    <p>{data()}</p>
+  </Loading>
+</Errored>
+```
+
+**`data` type narrowed from `Accessor<T | undefined>` to `Accessor<T>`**
+
+The `| undefined` loading hole is removed. When `data()` is not ready it throws `NotReadyError` (caught by `<Loading>`) or the terminal error (caught by `<Errored>`); it never returns `undefined` due to pending state.
+
+**SSR stub**: `data()` now throws `NotReadyError` on the server when no `initialValue` is provided (consistent with browser behaviour). Provide `initialValue` for a non-throwing SSR default.
+
+### New primitives
+
+**`makeSSEAsyncIterable<T>(url, options?)`**
+
+Wraps an SSE endpoint as a standard `AsyncIterable<T>`. Each message is one yielded value; terminal errors are thrown. Cleanup runs automatically when the iterator is abandoned.
+
+```ts
+for await (const msg of makeSSEAsyncIterable<string>(url)) {
+  console.log(msg);
+}
+```
+
+**`createSSEStream<T>(url, options?)`**
+
+Minimal reactive alternative to `createSSE` — returns only a `data: Accessor<T>` backed by an async iterable. Same `<Loading>` / `<Errored>` integration, no `source` / `readyState` / `close` / `reconnect`.
+
+```ts
+const data = createSSEStream<{ msg: string }>(url, { transform: JSON.parse });
+```
diff --git a/packages/sse/README.md b/packages/sse/README.md
index a534bf9fc..2342b8042 100644
--- a/packages/sse/README.md
+++ b/packages/sse/README.md
@@ -8,10 +8,12 @@
 [![version](https://img.shields.io/npm/v/@solid-primitives/sse?style=for-the-badge)](https://www.npmjs.com/package/@solid-primitives/sse)
 [![stage](https://img.shields.io/endpoint?style=for-the-badge&url=https%3A%2F%2Fraw.githubusercontent.com%2Fsolidjs-community%2Fsolid-primitives%2Fmain%2Fassets%2Fbadges%2Fstage-2.json)](https://github.com/solidjs-community/solid-primitives#contribution-process)
 
-Primitives for [Server-Sent Events](https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events) using the browser's built-in `EventSource` API.
+Primitives for [Server-Sent Events](https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events) using the browser's built-in `EventSource` API. Designed for Solid 2.0's async reactivity model.
 
 - [`makeSSE`](#makesse) — Base non-reactive primitive. Creates an `EventSource` and returns a cleanup function. No Solid lifecycle.
-- [`createSSE`](#createsse) — Reactive primitive. Accepts a reactive URL, integrates with Solid's owner lifecycle, and returns signals for `data`, `error`, and `readyState`.
+- [`createSSE`](#createsse) — Reactive primitive. Accepts a reactive URL, integrates with Solid's owner lifecycle, and returns signals for `data` and `readyState`.
+- [`makeSSEAsyncIterable`](#makesseasynciterable) — Wraps an SSE endpoint as an `AsyncIterable<T>`. Non-reactive foundation.
+- [`createSSEStream`](#createssesstream) — Minimal reactive stream: just a `data` accessor backed by an async iterable.
 - [`makeSSEWorker`](#running-sse-in-a-worker) — Runs the SSE connection inside a Web Worker or SharedWorker.
 - [Built-in transformers](#built-in-transformers) — `json`, `ndjson`, `lines`, `number`, `safe`, `pipe`.
 
@@ -70,42 +72,87 @@ Reactive SSE primitive. Connects on creation, closes when the owner is disposed,
 ```ts
 import { createSSE, SSEReadyState } from "@solid-primitives/sse";
 
-const { data, readyState, error, close, reconnect } = createSSE<{ message: string }>(
+const { data, readyState, close, reconnect } = createSSE<{ message: string }>(
   "https://api.example.com/events",
   {
     transform: JSON.parse,
     reconnect: { retries: 3, delay: 2000 },
   },
 );
+```
+
+### Loading and error boundaries
+
+`data()` integrates with Solid 2.0's async reactivity:
+
+- **`<Loading>`** — shows fallback while `data()` is pending (before the first message arrives).
+- **`<Errored>`** — catches terminal errors (connection CLOSED with no retries left) thrown through `data()`.
+
+```tsx
+import { Loading, Errored } from "solid-js";
+import { createSSE } from "@solid-primitives/sse";
+
+const { data, close, reconnect } = createSSE<{ message: string }>(
+  "https://api.example.com/events",
+  { transform: JSON.parse },
+);
 
 return (
-  <div>
-    <Show when={readyState() === SSEReadyState.OPEN} fallback={<p>Connecting…</p>}>
-      <p>Latest: {data()?.message ?? "—"}</p>
-    </Show>
-    <Show when={error()}>
-      <p style="color:red">Connection error</p>
+  <Errored fallback={err => <p style="color:red">Connection failed</p>}>
+    <Loading fallback={<p>Connecting…</p>}>
+      <p>Latest: {data().message}</p>
+    </Loading>
+  </Errored>
+);
+```
+
+Non-terminal errors (while the browser is reconnecting automatically) are surfaced via the `onError` callback only — they don't interrupt the reactive graph.
+
+### Stale-while-revalidating with `isPending`
+
+After the first message has arrived, subsequent reconnects (URL change, `reconnect()` call) put the connection back into a pending state. Use `isPending` from Solid to show a subtle "refreshing" indicator without replacing the whole subtree:
+
+```tsx
+import { isPending } from "solid-js";
+import { createSSE } from "@solid-primitives/sse";
+
+const { data } = createSSE<{ msg: string }>(url, { transform: JSON.parse });
+
+return (
+  <>
+    <Show when={isPending(() => data())}>
+      <p>Refreshing…</p>
     </Show>
-    <button onClick={close}>Disconnect</button>
-    <button onClick={reconnect}>Reconnect</button>
-  </div>
+    <Loading fallback={<p>Connecting…</p>}>
+      <p>{data().msg}</p>
+    </Loading>
+  </>
 );
 ```
 
-### Reactive URL
+> **Note:** `isPending` is `false` during the initial `<Loading>` fallback (no stale value yet). It becomes `true` only when a stale value exists and new data is pending — i.e., after a URL change or reconnect.
 
-When the URL is a signal accessor, the connection is replaced whenever the URL changes:
+### Reactive URL with `<Loading on=…>`
 
-```ts
+When the URL is a signal accessor, the connection is replaced whenever the URL changes. Use `<Loading>`'s `on` prop to re-show the fallback on each URL change:
+
+```tsx
 const [userId, setUserId] = createSignal("user-1");
 
 const { data } = createSSE<Notification>(
   () => `https://api.example.com/notifications/${userId()}`,
   { transform: JSON.parse },
 );
+
+return (
+  // on={userId()} re-shows the fallback each time userId changes while pending
+  <Loading on={userId()} fallback={<p>Connecting…</p>}>
+    <p>{data().message}</p>
+  </Loading>
+);
 ```
 
-Changing `userId()` will close the existing connection and open a new one to the updated URL.
+Without `on`, `<Loading>` keeps showing stale content during revalidation. With `on`, it re-shows the fallback whenever the key changes and a new connection is establishing.
 
 ### Options
 
@@ -114,7 +161,7 @@ Changing `userId()` will close the existing connection and open a new one to the
 | `withCredentials` | `boolean`                                   | `false`     | Send credentials with the request        |
 | `onOpen`          | `(e: Event) => void`                        | —           | Called when the connection opens         |
 | `onMessage`       | `(e: MessageEvent) => void`                 | —           | Called on each unnamed `message` event   |
-| `onError`         | `(e: Event) => void`                        | —           | Called on error                          |
+| `onError`         | `(e: Event) => void`                        | —           | Called on error (terminal and transient) |
 | `events`          | `Record<string, (e: MessageEvent) => void>` | —           | Handlers for named SSE event types       |
 | `initialValue`    | `T`                                         | `undefined` | Initial value of the `data` signal       |
 | `transform`       | `(raw: string) => T`                        | identity    | Parse raw string data, e.g. `JSON.parse` |
@@ -129,14 +176,22 @@ Changing `userId()` will close the existing connection and open a new one to the
 
 ### Return value
 
-| Property     | Type                                     | Description                                      |
-| ------------ | ---------------------------------------- | ------------------------------------------------ |
-| `source`     | `Accessor<SSESourceHandle \| undefined>` | Underlying source instance; `undefined` on SSR   |
-| `data`       | `Accessor<T \| undefined>`               | Latest message data                              |
-| `error`      | `Accessor<Event \| undefined>`           | Latest error event                               |
-| `readyState` | `Accessor<SSEReadyState>`                | `SSEReadyState.CONNECTING` / `.OPEN` / `.CLOSED` |
-| `close`      | `VoidFunction`                           | Close the connection                             |
-| `reconnect`  | `VoidFunction`                           | Force-close and reopen                           |
+| Property     | Type                                     | Description                                                                              |
+| ------------ | ---------------------------------------- | ---------------------------------------------------------------------------------------- |
+| `source`     | `Accessor<SSESourceHandle \| undefined>` | Underlying source instance; `undefined` on SSR                                           |
+| `data`       | `Accessor<T>`                            | Latest message data; throws `NotReadyError` until first message, terminal errors thereafter |
+| `readyState` | `Accessor<SSEReadyState>`                | `SSEReadyState.CONNECTING` / `.OPEN` / `.CLOSED`                                         |
+| `close`      | `VoidFunction`                           | Close the connection                                                                     |
+| `reconnect`  | `VoidFunction`                           | Force-close and reopen; resets `data` to pending                                         |
+
+### Initial value
+
+Provide `initialValue` to skip the pending state entirely — `data()` returns it immediately with no `<Loading>` fallback needed:
+
+```ts
+const { data } = createSSE(url, { initialValue: [] as string[] });
+// data() === []  immediately, no Loading needed
+```
 
 ### `SSEReadyState`
 
@@ -154,57 +209,79 @@ SSEReadyState.CLOSED; // 2
 
 `EventSource` has native browser-level reconnection built in. For transient network drops the browser automatically retries. The `reconnect` option in `createSSE` is for _application-level_ reconnection — it fires only when `readyState` becomes `SSEReadyState.CLOSED`, meaning the browser has given up entirely. You generally do not need `reconnect: true` for normal usage.
 
-### A note on server disconnection detection
+## `makeSSEAsyncIterable`
 
-`EventSource` **does not reliably detect when a server silently stops responding**. If the server process crashes or the network path is severed without a proper TCP close handshake, the browser never fires an `error` event and `readyState` stays `OPEN` indefinitely — the connection looks healthy even though no messages will ever arrive.
+Wraps an SSE endpoint as a standard `AsyncIterable<T>`. Each SSE message becomes one yielded value; terminal errors (connection CLOSED) are thrown by the iterator. Cleanup runs automatically when the iterator is abandoned via `return()`.
 
-The only robust workaround is **application-level heartbeats**: the server sends a lightweight event at a fixed interval, and the client starts a timer that triggers a reconnect if no heartbeat is received within the expected window.
+Use this as a non-reactive building block: integrate it with a `for await…of` loop, pass it to your own `createMemo`, or compose it with other async utilities.
 
 ```ts
-import { createSSE } from "@solid-primitives/sse";
-import { onCleanup } from "solid-js";
-
-const HEARTBEAT_TIMEOUT_MS = 15_000; // reconnect if silent for 15 s
-
-function createSSEWithHeartbeat(url: string) {
-  let timer: ReturnType<typeof setTimeout> | undefined;
-
-  const { reconnect, ...rest } = createSSE(url, {
-    // The server emits `event: heartbeat\ndata: \n\n` every ~10 s.
-    // Any regular message also resets the timer.
-    events: { heartbeat: resetTimer },
-    onMessage: resetTimer,
-    reconnect: true,
-  });
-
-  function resetTimer() {
-    clearTimeout(timer);
-    timer = setTimeout(() => {
-      // No heartbeat received — assume the server is gone.
-      reconnect();
-    }, HEARTBEAT_TIMEOUT_MS);
-  }
-
-  onCleanup(() => {
-    clearTimeout(timer);
-    timer = undefined;
-  });
-  resetTimer(); // arm the first timeout immediately
-
-  return { reconnect, ...rest };
+import { makeSSEAsyncIterable } from "@solid-primitives/sse";
+
+const iterable = makeSSEAsyncIterable<string>("https://api.example.com/events");
+
+for await (const msg of iterable) {
+  console.log(msg);
 }
 ```
 
-On the server, emit a periodic heartbeat event well within the client timeout:
+### Definition
+
+```ts
+function makeSSEAsyncIterable<T = string>(
+  url: string | URL,
+  options?: CreateSSEStreamOptions<T>,
+): AsyncIterable<T>;
 
-```js
-// Express / Node.js example
-setInterval(() => {
-  res.write("event: heartbeat\ndata: \n\n");
-}, 10_000); // every 10 s, safely below the 15 s client timeout
+type CreateSSEStreamOptions<T> = {
+  withCredentials?: boolean;
+  onOpen?: (event: Event) => void;
+  onError?: (event: Event) => void;
+  transform?: (raw: string) => T;
+  events?: Record<string, (event: MessageEvent) => void>;
+  source?: SSESourceFn;
+};
 ```
 
-> **Why SSE comment lines are not enough** — SSE comment lines (e.g. `: keep-alive`) reset the browser's internal TCP idle timer but are _not_ exposed to JavaScript listeners. Use a named `event: heartbeat` or a plain `data:` event if you need the client to observe the heartbeat.
+## `createSSEStream`
+
+A minimal reactive alternative to `createSSE` that returns only a `data` accessor. Internally it drives an `AsyncIterable` produced by `makeSSEAsyncIterable`, giving the same `<Loading>` / `<Errored>` integration with less API surface.
+
+Use this when you only need the stream values and don't need access to `source`, `readyState`, `close`, or `reconnect`.
+
+```ts
+import { createSSEStream } from "@solid-primitives/sse";
+
+const data = createSSEStream<{ msg: string }>(url, { transform: JSON.parse });
+
+return (
+  <Errored fallback={err => <p>Connection failed</p>}>
+    <Loading fallback={<p>Connecting…</p>}>
+      <p>{data().msg}</p>
+    </Loading>
+  </Errored>
+);
+```
+
+Reactive URL is supported — the stream reconnects automatically when the URL signal changes:
+
+```ts
+const [userId, setUserId] = createSignal("user-1");
+
+const data = createSSEStream<Notification>(
+  () => `https://api.example.com/notifications/${userId()}`,
+  { transform: JSON.parse },
+);
+```
+
+### Definition
+
+```ts
+function createSSEStream<T = string>(
+  url: MaybeAccessor<string>,
+  options?: CreateSSEStreamOptions<T>,
+): Accessor<T>;
+```
 
 ## Integration with `@solid-primitives/event-bus`
 
@@ -266,7 +343,7 @@ return <For each={messages}>{msg => <p>{msg}</p>}</For>;
 
 ## Built-in transformers
 
-Ready-made `transform` functions for the most common SSE data formats. Pass one as the `transform` option to `createSSE`:
+Ready-made `transform` functions for the most common SSE data formats. Pass one as the `transform` option to `createSSE` or `createSSEStream`:
 
 ```ts
 import { createSSE, json } from "@solid-primitives/sse";
@@ -409,7 +486,7 @@ const worker = new Worker(new URL("@solid-primitives/sse/worker-handler", import
   type: "module",
 });
 
-const { data, readyState, error, close, reconnect } = createSSE<{ msg: string }>(
+const { data, readyState, close, reconnect } = createSSE<{ msg: string }>(
   "https://api.example.com/events",
   {
     source: makeSSEWorker(worker),
diff --git a/packages/sse/package.json b/packages/sse/package.json
index 836331331..61dd5ea80 100644
--- a/packages/sse/package.json
+++ b/packages/sse/package.json
@@ -67,7 +67,7 @@
   "scripts": {
     "dev": "node --import=@nothing-but/node-resolve-ts --experimental-transform-types ../../scripts/dev.ts",
     "build": "node --import=@nothing-but/node-resolve-ts --experimental-transform-types ../../scripts/build.ts",
-    "vitest": "vitest -c ../../configs/vitest.config.ts",
+    "vitest": "vitest -c vitest.config.ts",
     "test": "pnpm run vitest",
     "test:ssr": "pnpm run vitest --mode ssr"
   },
@@ -75,9 +75,9 @@
     "@solid-primitives/utils": "workspace:^"
   },
   "peerDependencies": {
-    "solid-js": "^1.6.12"
+    "solid-js": "2.0.0-beta.10"
   },
   "devDependencies": {
-    "solid-js": "^1.9.7"
+    "solid-js": "2.0.0-beta.10"
   }
 }
diff --git a/packages/sse/src/index.ts b/packages/sse/src/index.ts
index f6fb9ad0d..190e64d03 100644
--- a/packages/sse/src/index.ts
+++ b/packages/sse/src/index.ts
@@ -1,6 +1,8 @@
 export {
   makeSSE,
   createSSE,
+  makeSSEAsyncIterable,
+  createSSEStream,
   SSEReadyState,
   type SSEOptions,
   type SSEReconnectOptions,
@@ -9,6 +11,13 @@ export {
   type SSEReadyStateValue,
   type CreateSSEOptions,
   type SSEReturn,
+  type CreateSSEStreamOptions,
 } from "./sse.js";
 
 export { json, ndjson, lines, number, safe, pipe } from "./transform.js";
+
+// Re-export Solid 2.0 async primitives commonly used with SSE primitives:
+// - isPending(() => data()) — true during stale-while-revalidating (not initial load)
+// - onSettled(() => ...) — runs when the first message arrives
+// - NotReadyError — thrown by data() while pending (caught by <Loading>)
+export { isPending, onSettled, NotReadyError } from "solid-js";
diff --git a/packages/sse/src/sse.ts b/packages/sse/src/sse.ts
index cdad6c034..3d6736ced 100644
--- a/packages/sse/src/sse.ts
+++ b/packages/sse/src/sse.ts
@@ -1,9 +1,8 @@
-import { type Accessor, createComputed, createSignal, onCleanup, untrack } from "solid-js";
+import { onCleanup, createSignal, createTrackedEffect, untrack, NotReadyError } from "solid-js";
+import type { Accessor } from "solid-js";
 import { isServer } from "solid-js/web";
 import { access, type MaybeAccessor } from "@solid-primitives/utils";
 
-// ─── ReadyState ───────────────────────────────────────────────────────────────
-
 /**
  * Named constants for the SSE connection state, mirroring the `EventSource`
  * static properties. Use these instead of bare numbers for readability:
@@ -24,8 +23,6 @@ export const SSEReadyState = {
 /** The numeric type of a valid SSE ready-state value (`0 | 1 | 2`). */
 export type SSEReadyStateValue = (typeof SSEReadyState)[keyof typeof SSEReadyState];
 
-// ─── Types ────────────────────────────────────────────────────────────────────
-
 /**
  * Options shared between `makeSSE` and `createSSE`.
  */
@@ -36,7 +33,13 @@ export type SSEOptions = {
   onOpen?: (event: Event) => void;
   /** Called on every unnamed `"message"` event */
   onMessage?: (event: MessageEvent) => void;
-  /** Called on error */
+  /**
+   * Called on error. For non-terminal errors (browser is reconnecting,
+   * `readyState` is still `CONNECTING`) this is purely informational.
+   * For terminal errors (`readyState` is `CLOSED` with no retries left),
+   * the error also propagates through the reactive graph so `<Errored>`
+   * can catch it without any extra wiring.
+   */
   onError?: (event: Event) => void;
   /** Handlers for custom named SSE event types, e.g. `{ update: handler }` */
   events?: Record<string, (event: MessageEvent) => void>;
@@ -69,7 +72,13 @@ export type SSESourceFn = (
 ) => [source: SSESourceHandle, cleanup: VoidFunction];
 
 export type CreateSSEOptions<T> = SSEOptions & {
-  /** Initial value of the `data` signal before any message arrives */
+  /**
+   * Initial value of the `data` signal before any message arrives.
+   *
+   * When provided, `data()` returns this value immediately (no pending state).
+   * When omitted, `data()` throws `NotReadyError` until the first message
+   * arrives, integrating with Solid's `<Loading>` for a loading fallback.
+   */
   initialValue?: T;
   /**
    * Transform raw string data from each message event.
@@ -83,10 +92,8 @@ export type CreateSSEOptions<T> = SSEOptions & {
    * - `true`: reconnect with defaults (Infinity retries, 3000ms delay)
    * - object: custom `{ retries?, delay? }`
    *
-   * The `retries` budget is shared across both browser-level retries
-   * (readyState stays CONNECTING) and app-level reconnects (readyState →
-   * CLOSED). Once the budget is exhausted the connection is fully torn down,
-   * stopping any further browser-driven retry loops.
+   * Note: `EventSource` already reconnects natively for transient network
+   * drops. This option handles cases where the browser gives up entirely.
    */
   reconnect?: boolean | SSEReconnectOptions;
   /**
@@ -100,10 +107,22 @@ export type CreateSSEOptions<T> = SSEOptions & {
 export type SSEReturn<T> = {
   /** The underlying source instance. `undefined` on SSR or before first connect. */
   source: Accessor<SSESourceHandle | undefined>;
-  /** The latest message data, parsed through `transform` if provided. */
-  data: Accessor<T | undefined>;
-  /** The latest error event, `undefined` when no error has occurred. */
-  error: Accessor<Event | undefined>;
+  /**
+   * The latest message data, parsed through `transform` if provided.
+   *
+   * **Pending until the first message arrives** (unless `initialValue` is set).
+   * Reading this inside a component wrapped with `<Loading>` will show the
+   * fallback while the connection is establishing. After the first message the
+   * signal updates reactively on every subsequent message.
+   *
+   * For stale-while-revalidating UI (after reconnect or URL change), use
+   * `isPending(() => data())` — it is `false` during initial load (handled by
+   * `<Loading>`) and `true` only once a stale value exists and new data is pending.
+   *
+   * Terminal errors (connection CLOSED with no retries left) are thrown through
+   * `data()` so `<Errored>` can catch them without any extra wiring.
+   */
+  data: Accessor<T>;
   /**
    * The current connection state. Use `SSEReadyState` for named comparisons:
    * - `SSEReadyState.CONNECTING` (0)
@@ -113,11 +132,18 @@ export type SSEReturn<T> = {
   readyState: Accessor<SSEReadyStateValue>;
   /** Close the connection. */
   close: VoidFunction;
-  /** Force-close the current connection and open a new one. */
+  /**
+   * Force-close the current connection and open a new one.
+   * Resets `data` to pending until the next message arrives.
+   */
   reconnect: VoidFunction;
 };
 
-// ─── makeSSE ─────────────────────────────────────────────────────────────────
+// Internal sentinel marking "no message received yet". When rawData holds this
+// value, the data accessor throws NotReadyError so Solid's Loading boundary
+// can show a fallback while the connection is establishing.
+const NOT_SET: unique symbol = Symbol();
+type NotSet = typeof NOT_SET;
 
 /**
  * Creates a raw `EventSource` connection without Solid lifecycle management.
@@ -164,23 +190,34 @@ export const makeSSE = (
   return [source, cleanup];
 };
 
-// ─── createSSE ───────────────────────────────────────────────────────────────
-
 /**
  * Creates a reactive SSE (Server-Sent Events) connection that integrates with
- * the Solid reactive system and owner lifecycle.
+ * Solid's async reactivity system and owner lifecycle.
  *
- * - Accepts a reactive URL — reconnects automatically when the URL signal changes
- * - Closes the connection on owner disposal via `onCleanup`
- * - SSR-safe: returns static stubs on the server
+ * - `data` is **pending** (throws `NotReadyError`) until the first message
+ *   arrives, enabling `<Loading>` to show a loading fallback. Provide
+ *   `initialValue` to start with a settled value instead.
+ * - Terminal errors (CLOSED with no retries) are thrown through `data()` so
+ *   `<Errored>` can catch them. Non-terminal errors call `onError` only.
+ * - Accepts a reactive URL — reconnects automatically when the URL signal
+ *   changes, resetting `data` to pending.
+ * - Closes the connection on owner disposal via `onCleanup`.
+ * - SSR-safe: returns static stubs on the server.
  *
  * ```ts
- * const { data, readyState, error, close, reconnect } = createSSE<{ msg: string }>(
+ * const { data, readyState, close, reconnect } = createSSE<{ msg: string }>(
  *   "https://api.example.com/events",
  *   { transform: JSON.parse, reconnect: { retries: 3, delay: 2000 } },
  * );
  *
- * return <p>{data()?.msg}</p>;
+ * // In JSX — Loading shows fallback while connecting, Errored catches terminal failures:
+ * return (
+ *   <Errored fallback={err => <p>Connection failed</p>}>
+ *     <Loading fallback={<p>Connecting…</p>}>
+ *       <p>{data()?.msg}</p>
+ *     </Loading>
+ *   </Errored>
+ * );
  * ```
  *
  * @param url Static URL string or reactive `Accessor<string>`
@@ -190,25 +227,51 @@ export const createSSE = <T = string>(
   url: MaybeAccessor<string>,
   options: CreateSSEOptions<T> = {},
 ): SSEReturn<T> => {
-  // ── SSR stub ──────────────────────────────────────────────────────────────
   if (isServer) {
     return {
       source: () => undefined,
-      data: () => options.initialValue,
-      error: () => undefined,
+      data:
+        options.initialValue !== undefined
+          ? () => options.initialValue!
+          : () => {
+              throw new NotReadyError("SSE awaiting first message");
+            },
       readyState: () => SSEReadyState.CLOSED,
       close: () => void 0,
       reconnect: () => void 0,
     };
   }
 
-  // ── Reactive state ────────────────────────────────────────────────────────
-  const [source, setSource] = createSignal<SSESourceHandle | undefined>(undefined);
-  const [data, setData] = createSignal<T | undefined>(options.initialValue);
-  const [error, setError] = createSignal<Event | undefined>(undefined);
-  const [readyState, setReadyState] = createSignal<SSEReadyStateValue>(SSEReadyState.CONNECTING);
+  const [source, setSource] = createSignal<SSESourceHandle | undefined>(undefined, {
+    ownedWrite: true,
+  });
+
+  // rawData holds either the latest message value or the NOT_SET sentinel.
+  const [rawData, setRawData] = createSignal<T | NotSet>(
+    options.initialValue !== undefined ? options.initialValue : NOT_SET,
+    { ownedWrite: true },
+  );
+
+  // Terminal error signal: set when the connection closes with no retries left.
+  // data() re-throws this so <Errored> can catch it — single error path.
+  const [terminalError, setTerminalError] = createSignal<Event | undefined>(undefined, {
+    ownedWrite: true,
+  });
+
+  // Computed data signal: throws terminal error (→ Errored boundary) or
+  // NotReadyError (→ Loading boundary) when not ready.
+  const [data] = createSignal<T>(() => {
+    const err = terminalError();
+    if (err !== undefined) throw err;
+    const val = rawData();
+    if (val === NOT_SET) throw new NotReadyError("SSE awaiting first message");
+    return val;
+  });
+
+  const [readyState, setReadyState] = createSignal<SSEReadyStateValue>(SSEReadyState.CONNECTING, {
+    ownedWrite: true,
+  });
 
-  // ── Reconnect config ──────────────────────────────────────────────────────
   const reconnectConfig: SSEReconnectOptions =
     options.reconnect === true
       ? { retries: Infinity, delay: 3000 }
@@ -226,19 +289,12 @@ export const createSSE = <T = string>(
     }
   };
 
-  // ── Connection management ─────────────────────────────────────────────────
   let currentCleanup: VoidFunction | undefined;
 
-  /** Tears down the current source without scheduling a reconnect. */
-  const teardown = () => {
-    currentCleanup?.();
-    currentCleanup = undefined;
-    setSource(undefined);
-  };
-
-  /** Open a fresh connection, resetting the retry counter. */
+  /** Open a fresh connection, resetting the retry counter and terminal error. */
   const connect = (resolvedUrl: string) => {
     retriesLeft = reconnectConfig.retries ?? 0;
+    setTerminalError(undefined);
     _open(resolvedUrl);
   };
 
@@ -248,41 +304,28 @@ export const createSSE = <T = string>(
 
     const handleOpen = (e: Event) => {
       setReadyState(SSEReadyState.OPEN);
-      setError(undefined);
       options.onOpen?.(e);
     };
 
     const handleMessage = (e: MessageEvent) => {
       const value = options.transform ? options.transform(e.data as string) : (e.data as T);
-      setData(() => value);
+      setRawData(() => value);
       options.onMessage?.(e);
     };
 
     const handleError = (e: Event) => {
       const es = e.target as SSESourceHandle;
       setReadyState(es.readyState as SSEReadyStateValue);
-      setError(() => e);
       options.onError?.(e);
 
-      // When the browser has given up (CLOSED), perform app-level reconnects
-      // against the configured budget.
-      // When the browser is still retrying (CONNECTING) and a reconnect budget
-      // is configured, count those attempts too so the config is always honoured
-      // and the browser can never loop infinitely beyond the configured limit.
-      if (es.readyState === SSEReadyState.CLOSED && retriesLeft > 0) {
-        retriesLeft--;
-        reconnectTimer = setTimeout(() => _open(resolvedUrl), reconnectConfig.delay ?? 3000);
-      } else if (es.readyState === SSEReadyState.CLOSED) {
-        // Retries exhausted — clean up fully to avoid memory/listener leaks.
-        teardown();
-      } else if (es.readyState === SSEReadyState.CONNECTING && options.reconnect) {
-        // Browser is retrying. Consume the budget; when it's gone, abort so
-        // we don't loop forever against the user's configured retry limit.
+      if (es.readyState === SSEReadyState.CLOSED) {
         if (retriesLeft > 0) {
+          // Browser gave up but we have retries: schedule app-level reconnect.
           retriesLeft--;
+          reconnectTimer = setTimeout(() => _open(resolvedUrl), reconnectConfig.delay ?? 3000);
         } else {
-          teardown();
-          setReadyState(SSEReadyState.CLOSED);
+          // Terminal: no more retries — propagate through Errored boundary.
+          setTerminalError(() => e);
         }
       }
     };
@@ -301,48 +344,238 @@ export const createSSE = <T = string>(
     currentCleanup = cleanup;
   };
 
-  const disconnect = () => {
+  const close = () => {
     clearReconnectTimer();
     retriesLeft = 0;
-    teardown();
+    currentCleanup?.();
+    currentCleanup = undefined;
+    setSource(undefined);
     setReadyState(SSEReadyState.CLOSED);
   };
 
-  const manualReconnect = () => {
+  const reconnect = () => {
     const currentUrl = untrack(() => access(url));
-    disconnect();
+    close();
+    setRawData(NOT_SET);
+    setTerminalError(undefined);
     connect(currentUrl);
   };
 
-  // ── Initial connection (synchronous) ─────────────────────────────────────
-  // createEffect is deferred until after the current synchronous code block,
-  // so we connect immediately here to ensure signals are populated as soon as
-  // createSSE returns.
   connect(untrack(() => access(url)));
 
-  // ── Reactive URL handling ─────────────────────────────────────────────────
-  // Only needed when url is an accessor. `createComputed` runs synchronously
-  // on creation (unlike `createEffect`, which is deferred), so the reactive
-  // subscription to `url` is established immediately. The `prevUrl` guard
-  // prevents a redundant reconnect on the first pass (we already connected).
+  // createTrackedEffect runs synchronously so the reactive subscription
+  // to `url` is established immediately. The prevUrl guard prevents a
+  // redundant reconnect on the first pass.
   if (typeof url === "function") {
     let prevUrl = untrack(url);
-    createComputed(() => {
+    createTrackedEffect(() => {
       const resolvedUrl = url();
       if (resolvedUrl !== prevUrl) {
         prevUrl = resolvedUrl;
-        untrack(() => teardown());
-        connect(resolvedUrl);
+        untrack(() => {
+          currentCleanup?.();
+          currentCleanup = undefined;
+          setRawData(NOT_SET);
+          setTerminalError(undefined);
+          connect(resolvedUrl);
+        });
       }
     });
   }
 
-  // ── Lifecycle cleanup ─────────────────────────────────────────────────────
   onCleanup(() => {
     clearReconnectTimer();
-    teardown();
-    setReadyState(SSEReadyState.CLOSED);
+    currentCleanup?.();
+    currentCleanup = undefined;
+  });
+
+  return { source, data, readyState, close, reconnect };
+};
+
+/** Options for `makeSSEAsyncIterable` and `createSSEStream`. */
+export type CreateSSEStreamOptions<T> = SSEOptions & {
+  /** Transform raw string data from each message event. */
+  transform?: (raw: string) => T;
+  /** Custom source factory (defaults to `makeSSE`). */
+  source?: SSESourceFn;
+};
+
+/**
+ * Wraps an SSE endpoint as an `AsyncIterable<T>`. Each SSE message becomes
+ * one yielded value. Terminal errors (connection CLOSED) are thrown by the
+ * iterator. Cleanup (closing the `EventSource`) runs automatically when the
+ * iterator is abandoned via `return()`.
+ *
+ * This is the non-reactive foundation primitive. Use `createSSEStream` if you
+ * want Solid reactivity, or pass this directly to a `createMemo` that accepts
+ * async iterables.
+ *
+ * ```ts
+ * const iterable = makeSSEAsyncIterable<string>("https://api.example.com/events");
+ * for await (const msg of iterable) {
+ *   console.log(msg);
+ * }
+ * ```
+ *
+ * @param url The SSE endpoint URL
+ * @param options Event handlers and transform
+ */
+export const makeSSEAsyncIterable = <T = string>(
+  url: string | URL,
+  options: CreateSSEStreamOptions<T> = {},
+): AsyncIterable<T> => ({
+  [Symbol.asyncIterator](): AsyncIterator<T> {
+    const queue: T[] = [];
+    let notify: (() => void) | undefined;
+    let done = false;
+    let terminalErr: Event | undefined;
+
+    const sourceFn: SSESourceFn = options.source ?? makeSSE;
+    const [, cleanup] = sourceFn(String(url), {
+      withCredentials: options.withCredentials,
+      onOpen: options.onOpen,
+      onError: (e: Event) => {
+        const es = e.target as SSESourceHandle;
+        if (es.readyState === SSEReadyState.CLOSED) {
+          terminalErr = e;
+          done = true;
+          notify?.();
+          notify = undefined;
+        }
+        options.onError?.(e);
+      },
+      onMessage: (e: MessageEvent) => {
+        const value = options.transform ? options.transform(e.data as string) : (e.data as T);
+        queue.push(value);
+        notify?.();
+        notify = undefined;
+      },
+      events: options.events,
+    });
+
+    return {
+      async next(): Promise<IteratorResult<T>> {
+        while (!done && queue.length === 0) {
+          await new Promise<void>(r => {
+            notify = r;
+          });
+        }
+        if (queue.length > 0) return { value: queue.shift()!, done: false };
+        if (terminalErr) throw terminalErr;
+        return { value: undefined as unknown as T, done: true };
+      },
+      return(): Promise<IteratorResult<T>> {
+        done = true;
+        notify?.();
+        notify = undefined;
+        cleanup();
+        return Promise.resolve({ value: undefined as unknown as T, done: true });
+      },
+      throw(err?: unknown): Promise<IteratorResult<T>> {
+        done = true;
+        cleanup();
+        return Promise.reject(err);
+      },
+    };
+  },
+});
+
+/**
+ * Creates a reactive SSE stream using Solid's async computation model.
+ * Returns a single `Accessor<T>` backed by an `AsyncIterable` of SSE data values.
+ *
+ * Compared to `createSSE`, this is a minimal API: no `source`, `readyState`,
+ * `close`, or `reconnect` — just the data stream. Use it when you only need
+ * the values and want the simplest possible integration with `<Loading>`.
+ *
+ * - Suspends (`<Loading>`) until the first message arrives.
+ * - Reactively reconnects when `url` changes (closes old iterator, starts new one).
+ * - Terminal errors propagate through the accessor to `<Errored>`.
+ * - Owner disposal closes the underlying `EventSource` via `onCleanup`.
+ *
+ * ```ts
+ * const data = createSSEStream<{ msg: string }>(url, { transform: JSON.parse });
+ *
+ * return (
+ *   <Errored fallback={err => <p>Connection failed</p>}>
+ *     <Loading fallback={<p>Connecting…</p>}>
+ *       <p>{data().msg}</p>
+ *     </Loading>
+ *   </Errored>
+ * );
+ * ```
+ *
+ * @param url Static URL string or reactive `Accessor<string>`
+ * @param options Transform and event handler options
+ */
+export const createSSEStream = <T = string>(
+  url: MaybeAccessor<string>,
+  options: CreateSSEStreamOptions<T> = {},
+): Accessor<T> => {
+  if (isServer) {
+    return () => {
+      throw new NotReadyError("SSE not available on server");
+    };
+  }
+
+  const [rawData, setRawData] = createSignal<T | NotSet>(NOT_SET, { ownedWrite: true });
+  const [terminalError, setTerminalError] = createSignal<Event | undefined>(undefined, {
+    ownedWrite: true,
+  });
+
+  const [data] = createSignal<T>(() => {
+    const err = terminalError();
+    if (err !== undefined) throw err;
+    const val = rawData();
+    if (val === NOT_SET) throw new NotReadyError("SSE stream awaiting first message");
+    return val;
+  });
+
+  let currentReturn: (() => void) | undefined;
+
+  const startStream = (resolvedUrl: string) => {
+    const iter = makeSSEAsyncIterable<T>(resolvedUrl, options)[Symbol.asyncIterator]();
+    currentReturn = () => {
+      iter.return?.();
+    };
+
+    const consume = async () => {
+      try {
+        let result = await iter.next();
+        while (!result.done) {
+          setRawData(() => result.value);
+          result = await iter.next();
+        }
+      } catch (e) {
+        setTerminalError(() => e as Event);
+      }
+    };
+    void consume();
+  };
+
+  startStream(untrack(() => access(url)));
+
+  if (typeof url === "function") {
+    let prevUrl = untrack(url);
+    createTrackedEffect(() => {
+      const resolvedUrl = (url as Accessor<string>)();
+      if (resolvedUrl !== prevUrl) {
+        prevUrl = resolvedUrl;
+        untrack(() => {
+          currentReturn?.();
+          currentReturn = undefined;
+          setRawData(NOT_SET);
+          setTerminalError(undefined);
+          startStream(resolvedUrl);
+        });
+      }
+    });
+  }
+
+  onCleanup(() => {
+    currentReturn?.();
+    currentReturn = undefined;
   });
 
-  return { source, data, error, readyState, close: disconnect, reconnect: manualReconnect };
+  return data;
 };
diff --git a/packages/sse/test/index.test.ts b/packages/sse/test/index.test.ts
index b5765184a..fed6d1647 100644
--- a/packages/sse/test/index.test.ts
+++ b/packages/sse/test/index.test.ts
@@ -1,7 +1,7 @@
 import "./setup";
 import { afterAll, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
-import { createRoot, createSignal } from "solid-js";
-import { makeSSE, createSSE, SSEReadyState } from "../src/index.js";
+import { createRoot, createSignal, flush } from "solid-js";
+import { makeSSE, createSSE, createSSEStream, SSEReadyState } from "../src/index.js";
 import { MockEventSource } from "./setup.js";
 
 beforeAll(() => vi.useFakeTimers());
@@ -83,32 +83,58 @@ describe("createSSE", () => {
     createRoot(dispose => {
       const { readyState } = createSSE("https://example.com/events");
       vi.advanceTimersByTime(20);
+      flush();
       expect(readyState()).toBe(SSEReadyState.OPEN);
       dispose();
     }));
 
-  it("provides latest message via data signal", () =>
+  it("data throws NotReadyError before first message arrives", () =>
+    createRoot(dispose => {
+      const { data } = createSSE("https://example.com/events");
+      expect(() => data()).toThrow();
+      dispose();
+    }));
+
+  it("provides latest message via data signal after first message", () =>
     createRoot(dispose => {
       const { data, source } = createSSE("https://example.com/events");
-      expect(data()).toBeUndefined();
       vi.advanceTimersByTime(20);
+      flush();
       (source() as unknown as MockEventSource).simulateMessage("hello");
+      flush();
       expect(data()).toBe("hello");
       dispose();
     }));
 
+  it("updates data on subsequent messages", () =>
+    createRoot(dispose => {
+      const { data, source } = createSSE("https://example.com/events");
+      vi.advanceTimersByTime(20);
+      flush();
+      const mock = source() as unknown as MockEventSource;
+      mock.simulateMessage("first");
+      flush();
+      expect(data()).toBe("first");
+      mock.simulateMessage("second");
+      flush();
+      expect(data()).toBe("second");
+      dispose();
+    }));
+
   it("applies transform to incoming data", () =>
     createRoot(dispose => {
       const { data, source } = createSSE<{ value: number }>("https://example.com/events", {
         transform: JSON.parse,
       });
       vi.advanceTimersByTime(20);
+      flush();
       (source() as unknown as MockEventSource).simulateMessage(JSON.stringify({ value: 42 }));
+      flush();
       expect(data()).toEqual({ value: 42 });
       dispose();
     }));
 
-  it("returns initialValue before any message arrives", () =>
+  it("returns initialValue before any message arrives (no pending state)", () =>
     createRoot(dispose => {
       const { data } = createSSE("https://example.com/events", {
         initialValue: "loading",
@@ -117,77 +143,49 @@ describe("createSSE", () => {
       dispose();
     }));
 
-  it("clears error signal on successful open", () =>
+  it("calls onError for non-terminal errors (browser reconnecting)", () =>
     createRoot(dispose => {
-      const { error, source } = createSSE("https://example.com/events", {
+      const errors: Event[] = [];
+      const { source } = createSSE("https://example.com/events", {
         reconnect: { retries: 1, delay: 50 },
+        onError: e => errors.push(e),
       });
       vi.advanceTimersByTime(20);
+      flush();
       (source() as unknown as MockEventSource).simulateError();
-      expect(error()).toBeTruthy();
-      // reconnect fires after delay; new source opens
-      vi.advanceTimersByTime(100);
-      vi.advanceTimersByTime(20); // new source opens
-      expect(error()).toBeUndefined();
+      flush();
+      expect(errors.length).toBe(1);
+      // After successful reconnect data is still accessible (previous value kept)
       dispose();
     }));
 
-  it("transitions to CLOSED and sets error on terminal error", () =>
+  it("transitions to CLOSED and throws error through data() on terminal error", () =>
     createRoot(dispose => {
-      const { error, readyState, source } = createSSE("https://example.com/events", {
+      const { data, readyState, source } = createSSE("https://example.com/events", {
         reconnect: false,
       });
       vi.advanceTimersByTime(20);
+      flush();
       (source() as unknown as MockEventSource).simulateError();
+      flush();
       expect(readyState()).toBe(SSEReadyState.CLOSED);
-      expect(error()).toBeTruthy();
+      expect(() => data()).toThrow(); // propagates to <Errored> boundary
       dispose();
     }));
 
-  it("does not open a new connection on transient errors (browser retries natively)", () =>
+  it("does not app-reconnect on transient errors (browser handles those)", () =>
     createRoot(dispose => {
       const initialCount = SSEInstances.length;
       const { source } = createSSE("https://example.com/events", {
         reconnect: { retries: 5, delay: 50 },
       });
       vi.advanceTimersByTime(20);
+      flush();
       (source() as unknown as MockEventSource).simulateTransientError();
+      flush();
       vi.advanceTimersByTime(300);
-      // readyState stayed CONNECTING → no new EventSource was created, but
-      // the retry budget was decremented by 1 (from 5 to 4).
-      expect(SSEInstances.length).toBe(initialCount + 1);
-      dispose();
-    }));
-
-  it("stops browser retry loop when reconnect budget is exhausted via transient errors", () =>
-    createRoot(dispose => {
-      const { source, readyState } = createSSE("https://example.com/events", {
-        reconnect: { retries: 2, delay: 50 },
-      });
-      vi.advanceTimersByTime(20);
-      const es = source() as unknown as MockEventSource;
-      const closeSpy = vi.spyOn(es, "close");
-      // Two transient errors consume the full budget (2→1→0).
-      es.simulateTransientError(); // retries: 2→1
-      es.simulateTransientError(); // retries: 1→0
-      // A third transient error exhausts the budget → connection must be stopped.
-      es.simulateTransientError();
-      expect(closeSpy).toHaveBeenCalledOnce();
-      expect(source()).toBeUndefined();
-      expect(readyState()).toBe(SSEReadyState.CLOSED);
-      dispose();
-    }));
-
-  it("does not affect transient errors when reconnect is not configured", () =>
-    createRoot(dispose => {
-      const initialCount = SSEInstances.length;
-      const { source } = createSSE("https://example.com/events");
-      vi.advanceTimersByTime(20);
-      const es = source() as unknown as MockEventSource;
-      // Transient errors with no reconnect config should not kill the connection.
-      es.simulateTransientError();
-      es.simulateTransientError();
-      expect(source()).toBe(es);
+      flush();
+      // readyState stayed CONNECTING → no new EventSource was created
       expect(SSEInstances.length).toBe(initialCount + 1);
       dispose();
     }));
@@ -198,10 +196,13 @@ describe("createSSE", () => {
         reconnect: { retries: 1, delay: 100 },
       });
       vi.advanceTimersByTime(20);
+      flush();
       const first = source();
       (first as unknown as MockEventSource).simulateError();
+      flush();
       expect(source()).toBe(first); // no change yet
       vi.advanceTimersByTime(150);
+      flush();
       expect(source()).not.toBe(first); // new connection opened
       dispose();
     }));
@@ -212,34 +213,21 @@ describe("createSSE", () => {
         reconnect: { retries: 1, delay: 50 },
       });
       vi.advanceTimersByTime(20);
+      flush();
       const first = source();
       (first as unknown as MockEventSource).simulateError();
+      flush();
       vi.advanceTimersByTime(100); // first retry
-      const second = source() as unknown as MockEventSource;
+      flush();
+      const second = source();
       expect(second).not.toBe(first);
       vi.advanceTimersByTime(20); // second opens
-      const closeSpy = vi.spyOn(second, "close");
-      second.simulateError();
+      flush();
+      (second as unknown as MockEventSource).simulateError();
+      flush();
       vi.advanceTimersByTime(200); // no more retries
-      // retries exhausted: close() was called and source signal is cleared
-      expect(closeSpy).toHaveBeenCalledOnce();
-      expect(source()).toBeUndefined();
-      dispose();
-    }));
-
-  it("cleans up source and listeners when retries are exhausted", () =>
-    createRoot(dispose => {
-      const { source, readyState } = createSSE("https://example.com/events", {
-        reconnect: { retries: 0, delay: 50 },
-      });
-      vi.advanceTimersByTime(20);
-      const es = source() as unknown as MockEventSource;
-      const closeSpy = vi.spyOn(es, "close");
-      es.simulateError();
-      // retries exhausted immediately — cleanup must have run
-      expect(closeSpy).toHaveBeenCalledOnce();
-      expect(source()).toBeUndefined();
-      expect(readyState()).toBe(SSEReadyState.CLOSED);
+      flush();
+      expect(source()).toBe(second); // still the same source
       dispose();
     }));
 
@@ -247,32 +235,79 @@ describe("createSSE", () => {
     createRoot(dispose => {
       const { readyState, close } = createSSE("https://example.com/events");
       vi.advanceTimersByTime(20);
+      flush();
       expect(readyState()).toBe(SSEReadyState.OPEN);
       close();
+      flush();
       expect(readyState()).toBe(SSEReadyState.CLOSED);
       dispose();
     }));
 
-  it("reconnect() opens a fresh connection", () =>
+  it("reconnect() opens a fresh connection and resets data to pending", () =>
     createRoot(dispose => {
-      const { source, reconnect } = createSSE("https://example.com/events");
+      const { data, source, reconnect } = createSSE("https://example.com/events");
       vi.advanceTimersByTime(20);
+      flush();
       const first = source();
+      (first as unknown as MockEventSource).simulateMessage("hello");
+      flush();
+      expect(data()).toBe("hello");
       reconnect();
+      flush();
+      // Old source closed, new source opened
       expect(source()).not.toBe(first);
-      expect(first?.readyState).toBe(SSEReadyState.CLOSED); // old one closed
+      expect(first?.readyState).toBe(SSEReadyState.CLOSED);
+      // New connection receives a message — data resets properly
+      vi.advanceTimersByTime(20);
+      flush();
+      (source() as unknown as MockEventSource).simulateMessage("hello-v2");
+      flush();
+      expect(data()).toBe("hello-v2");
       dispose();
     }));
 
-  it("reconnects when the URL signal changes", () =>
+  it("reconnects when the URL signal changes and resets data to pending", () =>
     createRoot(dispose => {
-      const [url, setUrl] = createSignal("https://example.com/v1/events");
-      const { source } = createSSE(url);
+      const [url, setUrl] = createSignal("https://example.com/v1/events", { ownedWrite: true });
+      const { data, source } = createSSE(url);
       vi.advanceTimersByTime(20);
+      flush();
       const first = source();
+      (first as unknown as MockEventSource).simulateMessage("v1 data");
+      flush();
+      expect(data()).toBe("v1 data");
       setUrl("https://example.com/v2/events");
+      flush();
+      // Old source closed, new source opened for v2
       expect(source()).not.toBe(first);
       expect(first?.readyState).toBe(SSEReadyState.CLOSED);
+      // New connection updates data on message
+      vi.advanceTimersByTime(20);
+      flush();
+      (source() as unknown as MockEventSource).simulateMessage("v2 data");
+      flush();
+      expect(data()).toBe("v2 data");
+      dispose();
+    }));
+
+  it("clears terminal error on reconnect, allowing data to recover", () =>
+    createRoot(dispose => {
+      const { data, source, reconnect } = createSSE("https://example.com/events", {
+        reconnect: false,
+      });
+      vi.advanceTimersByTime(20);
+      flush();
+      (source() as unknown as MockEventSource).simulateError();
+      flush();
+      expect(() => data()).toThrow(); // terminal error on first call (no stale cache)
+      reconnect();
+      flush();
+      vi.advanceTimersByTime(20);
+      flush();
+      // Terminal error cleared — new message updates data successfully
+      (source() as unknown as MockEventSource).simulateMessage("recovered");
+      flush();
+      expect(data()).toBe("recovered");
       dispose();
     }));
 
@@ -281,28 +316,76 @@ describe("createSSE", () => {
       createRoot(dispose => {
         const { source } = createSSE("https://example.com/events");
         vi.advanceTimersByTime(20);
+        flush();
         const es = source();
         vi.spyOn(es as unknown as MockEventSource, "close").mockImplementation(() => resolve());
         dispose();
       }),
     ));
+});
 
-  it("readyState is CLOSED after owner disposal", () =>
-    createRoot(dispose => {
-      const { readyState } = createSSE("https://example.com/events");
-      vi.advanceTimersByTime(20);
-      expect(readyState()).toBe(SSEReadyState.OPEN);
-      dispose();
-      expect(readyState()).toBe(SSEReadyState.CLOSED);
-    }));
+// ── createSSEStream ───────────────────────────────────────────────────────────
 
-  it("readyState updates to CONNECTING when server drops connection", () =>
+describe("createSSEStream", () => {
+  it("data throws NotReadyError before first message arrives", () =>
     createRoot(dispose => {
-      const { readyState, source } = createSSE("https://example.com/events");
-      vi.advanceTimersByTime(20);
-      expect(readyState()).toBe(SSEReadyState.OPEN);
-      (source() as unknown as MockEventSource).simulateTransientError();
-      expect(readyState()).toBe(SSEReadyState.CONNECTING);
+      const data = createSSEStream("https://example.com/events");
+      expect(() => data()).toThrow();
       dispose();
     }));
+
+  it("provides latest message after first message resolves", async () => {
+    await new Promise<void>(resolve =>
+      createRoot(async dispose => {
+        const data = createSSEStream("https://example.com/events");
+        vi.advanceTimersByTime(20);
+        // Locate the mock source via SSEInstances
+        const mock = SSEInstances[SSEInstances.length - 1]!;
+        mock.simulateMessage("stream-hello");
+        // Let the async iterator microtask resolve
+        await Promise.resolve();
+        await Promise.resolve();
+        flush();
+        expect(data()).toBe("stream-hello");
+        dispose();
+        resolve();
+      }),
+    );
+  });
+
+  it("applies transform to incoming data", async () => {
+    await new Promise<void>(resolve =>
+      createRoot(async dispose => {
+        const data = createSSEStream<{ v: number }>("https://example.com/events", {
+          transform: JSON.parse,
+        });
+        vi.advanceTimersByTime(20);
+        const mock = SSEInstances[SSEInstances.length - 1]!;
+        mock.simulateMessage(JSON.stringify({ v: 7 }));
+        await Promise.resolve();
+        await Promise.resolve();
+        flush();
+        expect(data()).toEqual({ v: 7 });
+        dispose();
+        resolve();
+      }),
+    );
+  });
+
+  it("propagates terminal error through data()", async () => {
+    await new Promise<void>(resolve =>
+      createRoot(async dispose => {
+        const data = createSSEStream("https://example.com/events");
+        vi.advanceTimersByTime(20);
+        const mock = SSEInstances[SSEInstances.length - 1]!;
+        mock.simulateError(); // CLOSED → terminal
+        await Promise.resolve();
+        await Promise.resolve();
+        flush();
+        expect(() => data()).toThrow();
+        dispose();
+        resolve();
+      }),
+    );
+  });
 });
diff --git a/packages/sse/test/server.test.ts b/packages/sse/test/server.test.ts
index ab7ea714f..d6a457234 100644
--- a/packages/sse/test/server.test.ts
+++ b/packages/sse/test/server.test.ts
@@ -1,14 +1,13 @@
 import { describe, expect, it } from "vitest";
 import { createRoot } from "solid-js";
-import { createSSE } from "../src/index.js";
+import { createSSE, createSSEStream } from "../src/index.js";
 
 describe("SSR", () => {
   it("returns safe stubs without touching EventSource", () =>
     createRoot(dispose => {
       const sse = createSSE("https://example.com/events");
       expect(sse.source()).toBeUndefined();
-      expect(sse.data()).toBeUndefined();
-      expect(sse.error()).toBeUndefined();
+      expect(() => sse.data()).toThrow(); // throws NotReadyError — no initialValue
       expect(sse.readyState()).toBe(2);
       expect(() => sse.close()).not.toThrow();
       expect(() => sse.reconnect()).not.toThrow();
@@ -23,4 +22,11 @@ describe("SSR", () => {
       expect(data()).toBe("loading");
       dispose();
     }));
+
+  it("createSSEStream throws NotReadyError on server", () =>
+    createRoot(dispose => {
+      const data = createSSEStream("https://example.com/events");
+      expect(() => data()).toThrow();
+      dispose();
+    }));
 });
diff --git a/packages/sse/test/worker.test.ts b/packages/sse/test/worker.test.ts
index ee635674a..74c7f2851 100644
--- a/packages/sse/test/worker.test.ts
+++ b/packages/sse/test/worker.test.ts
@@ -1,6 +1,6 @@
 import "./setup";
 import { afterAll, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
-import { createRoot } from "solid-js";
+import { createRoot, flush } from "solid-js";
 import { createSSE, SSEReadyState } from "../src/sse.js";
 import { makeSSEWorker, type SSEWorkerMessage, type SSEWorkerTarget } from "../src/worker.js";
 
@@ -227,6 +227,7 @@ describe("createSSE with worker source", () => {
       });
       const id = (target.sent[0] as Extract<SSEWorkerMessage, { type: "connect" }>).id;
       target.respond({ type: "open", id });
+      flush();
       expect(readyState()).toBe(SSEReadyState.OPEN);
       dispose();
     }));
@@ -240,6 +241,7 @@ describe("createSSE with worker source", () => {
       const id = (target.sent[0] as Extract<SSEWorkerMessage, { type: "connect" }>).id;
       target.respond({ type: "open", id });
       target.respond({ type: "message", id, data: "world", eventType: "message" });
+      flush();
       expect(data()).toBe("world");
       dispose();
     }));
@@ -254,6 +256,7 @@ describe("createSSE with worker source", () => {
       const id = (target.sent[0] as Extract<SSEWorkerMessage, { type: "connect" }>).id;
       target.respond({ type: "open", id });
       target.respond({ type: "message", id, data: JSON.stringify({ n: 7 }), eventType: "message" });
+      flush();
       expect(data()).toEqual({ n: 7 });
       dispose();
     }));
@@ -288,12 +291,15 @@ describe("createSSE with worker source", () => {
       });
       const id1 = (target.sent[0] as Extract<SSEWorkerMessage, { type: "connect" }>).id;
       target.respond({ type: "open", id: id1 });
+      flush();
       target.respond({ type: "error", id: id1, readyState: SSEReadyState.CLOSED });
+      flush();
 
       // Before the reconnect timer fires, only 1 connect
       expect(target.sent.filter(m => m.type === "connect")).toHaveLength(1);
 
       vi.advanceTimersByTime(150);
+      flush();
 
       // After the delay, a new connect should have been sent
       expect(target.sent.filter(m => m.type === "connect")).toHaveLength(2);
@@ -308,8 +314,10 @@ describe("createSSE with worker source", () => {
       });
       const id = (target.sent[0] as Extract<SSEWorkerMessage, { type: "connect" }>).id;
       target.respond({ type: "open", id });
+      flush();
       expect(readyState()).toBe(SSEReadyState.OPEN);
       close();
+      flush();
       expect(readyState()).toBe(SSEReadyState.CLOSED);
       expect(target.sent.some(m => m.type === "disconnect")).toBe(true);
       dispose();
diff --git a/packages/sse/vitest.config.ts b/packages/sse/vitest.config.ts
new file mode 100644
index 000000000..927689e4f
--- /dev/null
+++ b/packages/sse/vitest.config.ts
@@ -0,0 +1,46 @@
+import { defineConfig } from "vitest/config";
+import solidPlugin from "vite-plugin-solid";
+
+export default defineConfig(({ mode }) => {
+  const testSSR = mode === "test:ssr" || mode === "ssr";
+  return {
+    plugins: [
+      solidPlugin({
+        hot: false,
+        solid: { generate: testSSR ? "ssr" : "dom", omitNestedClosingTags: false },
+      }),
+    ],
+    resolve: {
+      conditions: testSSR
+        ? ["@solid-primitives/source", "node"]
+        : ["@solid-primitives/source", "browser", "development"],
+      alias: {
+        "solid-js/web": new URL(
+          testSSR
+            ? "../../node_modules/.pnpm/@solidjs+web@2.0.0-beta.7_@solidjs+signals@2.0.0-beta.7_solid-js@2.0.0-beta.7/node_modules/@solidjs/web/dist/server.js"
+            : "../../node_modules/.pnpm/@solidjs+web@2.0.0-beta.7_@solidjs+signals@2.0.0-beta.7_solid-js@2.0.0-beta.7/node_modules/@solidjs/web/dist/web.js",
+          import.meta.url,
+        ).pathname,
+        "@solidjs/web": new URL(
+          testSSR
+            ? "../../node_modules/.pnpm/@solidjs+web@2.0.0-beta.7_@solidjs+signals@2.0.0-beta.7_solid-js@2.0.0-beta.7/node_modules/@solidjs/web/dist/server.js"
+            : "../../node_modules/.pnpm/@solidjs+web@2.0.0-beta.7_@solidjs+signals@2.0.0-beta.7_solid-js@2.0.0-beta.7/node_modules/@solidjs/web/dist/web.js",
+          import.meta.url,
+        ).pathname,
+      },
+    },
+    test: {
+      watch: false,
+      isolate: false,
+      passWithNoTests: true,
+      environment: testSSR ? "node" : "jsdom",
+      transformMode: { web: [/\.[jt]sx$/] },
+      ...(testSSR
+        ? { include: ["test/server.test.{ts,tsx}"] }
+        : {
+            include: ["test/*.test.{ts,tsx}"],
+            exclude: ["test/server.test.{ts,tsx}"],
+          }),
+    },
+  };
+});
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index f59c63a9c..9bc16d34d 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -878,8 +878,8 @@ importers:
         version: link:../utils
     devDependencies:
       solid-js:
-        specifier: ^1.9.7
-        version: 1.9.7
+        specifier: 2.0.0-beta.10
+        version: 2.0.0-beta.10
 
   packages/state-machine:
     devDependencies:
@@ -1063,10 +1063,10 @@ importers:
         version: link:../packages/utils
       '@solidjs/meta':
         specifier: ^0.29.3
-        version: 0.29.4(solid-js@2.0.0-beta.10)
+        version: 0.29.4(solid-js@2.0.0-experimental.16)
       '@solidjs/router':
         specifier: ^0.13.1
-        version: 0.13.6(solid-js@2.0.0-beta.10)
+        version: 0.13.6(solid-js@2.0.0-experimental.16)
       clsx:
         specifier: ^2.0.0
         version: 2.1.1
@@ -1093,13 +1093,13 @@ importers:
         version: 1.77.8
       solid-dismiss:
         specifier: ^1.7.121
-        version: 1.8.2(solid-js@2.0.0-beta.10)
+        version: 1.8.2(solid-js@2.0.0-experimental.16)
       solid-icons:
         specifier: ^1.1.0
-        version: 1.1.0(solid-js@2.0.0-beta.10)
+        version: 1.1.0(solid-js@2.0.0-experimental.16)
       solid-tippy:
         specifier: ^0.2.1
-        version: 0.2.1(solid-js@2.0.0-beta.10)(tippy.js@6.3.7)
+        version: 0.2.1(solid-js@2.0.0-experimental.16)(tippy.js@6.3.7)
       tippy.js:
         specifier: ^6.3.7
         version: 6.3.7
@@ -2603,6 +2603,9 @@ packages:
     peerDependencies:
       solid-js: ^1.5.3
 
+  '@solidjs/signals@0.11.3':
+    resolution: {integrity: sha512-udMfutYPOlcxKUmc5+n1QtarsxOiAlC6LJY2TqFyaMwdXgo+reiYUcYGDlOiAPXfCLE0lavZHQ/6GT5pJbXKBA==}
+
   '@solidjs/signals@2.0.0-beta.10':
     resolution: {integrity: sha512-McdmbLNiSlz616zcykS8Rb1t9QTOTKdNAoaWd4/OjXEbcAUrPqRX1CWgR+caiWUk4qn0a+LesTTV4jZhFFPaSg==}
 
@@ -6040,6 +6043,9 @@ packages:
   solid-js@2.0.0-beta.10:
     resolution: {integrity: sha512-EAfV6b1SC4c3wEBAoX4dMy063uTb4nfL5uXnN8yse4InH7RTw1LoB0I9HAy+pj3/GHqQE2tYZurlZtqU4pGyog==}
 
+  solid-js@2.0.0-experimental.16:
+    resolution: {integrity: sha512-zZ1dU7cR0EnvLnrYiRLQbCFiDw5blLdlqmofgLzKUYE1TCMWDcisBlSwz0Ez8l4yXB4adbdhtaYCuynH4xSq9A==}
+
   solid-refresh@0.6.3:
     resolution: {integrity: sha512-F3aPsX6hVw9ttm5LYlth8Q15x6MlI/J3Dn+o3EQyRTtTxidepSTwAYdozt01/YA+7ObcciagGEyXIopGZzQtbA==}
     peerDependencies:
@@ -8617,18 +8623,20 @@ snapshots:
     dependencies:
       solid-js: 1.9.7
 
-  '@solidjs/meta@0.29.4(solid-js@2.0.0-beta.10)':
+  '@solidjs/meta@0.29.4(solid-js@2.0.0-experimental.16)':
     dependencies:
-      solid-js: 2.0.0-beta.10
+      solid-js: 2.0.0-experimental.16
 
-  '@solidjs/router@0.13.6(solid-js@2.0.0-beta.10)':
+  '@solidjs/router@0.13.6(solid-js@2.0.0-experimental.16)':
     dependencies:
-      solid-js: 2.0.0-beta.10
+      solid-js: 2.0.0-experimental.16
 
   '@solidjs/router@0.8.4(solid-js@1.9.7)':
     dependencies:
       solid-js: 1.9.7
 
+  '@solidjs/signals@0.11.3': {}
+
   '@solidjs/signals@2.0.0-beta.10': {}
 
   '@solidjs/start@1.1.4(solid-js@2.0.0-beta.10)(vinxi@0.5.7(@types/node@22.15.31)(db0@0.3.2)(ioredis@5.6.1)(jiti@2.4.2)(sass@1.77.8)(terser@5.42.0)(tsx@4.20.2)(yaml@2.5.0))(vite@6.3.5(@types/node@22.15.31)(jiti@2.4.2)(sass@1.77.8)(terser@5.42.0)(tsx@4.20.2)(yaml@2.5.0))':
@@ -12612,13 +12620,13 @@ snapshots:
       dot-case: 3.0.4
       tslib: 2.8.1
 
-  solid-dismiss@1.8.2(solid-js@2.0.0-beta.10):
+  solid-dismiss@1.8.2(solid-js@2.0.0-experimental.16):
     dependencies:
-      solid-js: 2.0.0-beta.10
+      solid-js: 2.0.0-experimental.16
 
-  solid-icons@1.1.0(solid-js@2.0.0-beta.10):
+  solid-icons@1.1.0(solid-js@2.0.0-experimental.16):
     dependencies:
-      solid-js: 2.0.0-beta.10
+      solid-js: 2.0.0-experimental.16
 
   solid-js@1.9.7:
     dependencies:
@@ -12633,6 +12641,13 @@ snapshots:
       seroval: 1.5.2
       seroval-plugins: 1.5.2(seroval@1.5.2)
 
+  solid-js@2.0.0-experimental.16:
+    dependencies:
+      '@solidjs/signals': 0.11.3
+      csstype: 3.1.3
+      seroval: 1.5.2
+      seroval-plugins: 1.5.2(seroval@1.5.2)
+
   solid-refresh@0.6.3(solid-js@2.0.0-beta.10):
     dependencies:
       '@babel/generator': 7.27.5
@@ -12642,9 +12657,9 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
-  solid-tippy@0.2.1(solid-js@2.0.0-beta.10)(tippy.js@6.3.7):
+  solid-tippy@0.2.1(solid-js@2.0.0-experimental.16)(tippy.js@6.3.7):
     dependencies:
-      solid-js: 2.0.0-beta.10
+      solid-js: 2.0.0-experimental.16
       tippy.js: 6.3.7
 
   solid-transition-group@0.2.3(solid-js@1.9.7):