Add a ChatStream-Octane experimental workload

suites-experimental/chat-stream/.gitignore

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+node_modules

suites-experimental/chat-stream/README.md

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+# ChatStream
+
+An LLM chat client: a sidebar of conversations, a message list, and a
+composer, with assistant replies streamed in a few tokens at a time and
+rendered as Markdown. It is written in Octane (`octane/App.tsrx`,
+ChatStream-Octane). The corpus, Markdown parser, network stub and stylesheet
+are in `shared/`.
+
+It is an original app and ships no third-party assets. It is adapted from the
+`chat-stream` benchmark in the Octane repository, with Markdown replies, code
+highlighting and scroll pinning added.
+
+## What are we testing
+
+-   Streaming: chunks append to the reply's text, and rendering re-parses the
+    reply's Markdown. Unchanged blocks keep their identity across parses (the
+    memoized-Markdown pattern streaming chat UIs use), so `memo` skips all but
+    the blocks that grew.
+-   Code blocks highlighted into one span per token, the way chat UIs' regex
+    highlighters produce them.
+-   Scroll pinning with CSS scroll anchoring: an anchor element after the
+    messages (the list's only `overflow-anchor: auto` candidate) keeps the
+    newest text in view as replies grow and conversations switch. The browser
+    adjusts the scroll position during its own layout, so no script reads
+    layout after a commit.
+-   Mounting and unmounting whole conversations, up to 200 messages.
+-   A controlled composer updated on every keystroke.
+
+## How are we testing
+
+All content comes from one fixed seed in `shared/corpus.js`. There is no network,
+storage, `Math.random` or `Date.now`, so every run renders the same
+conversations and streams the same replies.
+
+`shared/network.js` stands in for a streaming fetch. Each `window.deliverChunk()`
+call hands the open reply its next four tokens, so chunk arrival is
+deterministic and needs no timers.
+
+The app commits the way the Octane fixture of the chat-stream benchmark in the
+Octane repository does. Its event handlers only set state, and the steps commit
+it through `window.__benchFlush` after every interaction, as that benchmark's
+`run.mjs` does. Each chunk renders with `flushSync`, since a chunk arrives
+outside any event. So each send, chunk, conversation click and keystroke is on
+screen before the step's next interaction. A step stops delivering chunks once
+the reply loses its `streaming` class (see `chatStreamTests` in
+`suites-experimental/suites.mjs`). No step yields to the event loop before it
+ends, so every browser paints once per step.
+
+-   `StreamReplies`: sends three prompts in turn in the first conversation,
+    streaming each reply to completion before sending the next.
+-   `SwitchConversations`: clicks every conversation in the sidebar, then returns
+    to the first.
+-   `StreamIntoLongConversation`: streams one reply at the end of the
+    200-message conversation.
+-   `TypePrompt`: types a 163-character prompt into the composer one character
+    at a time.
+
+The composer uses `onInput`, which fires for every input event, including the
+ones the benchmark dispatches after setting the value from script.
+
+## Developer Documentation
+
+The app is built with Vite. It can be previewed during development with
+`npm run dev`. To update the files run in the harness, run `npm run build`,
+which regenerates the committed `dist/octane` directory and its
+`resources.txt`.
+
+The built workload can be loaded within the harness at e.g.
+`http://localhost:8080/?developerMode&suites=ChatStream-Octane`.

suites-experimental/chat-stream/dist/octane/index.html

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+<!DOCTYPE html>
+<html lang="en">
+    <head>
+        <meta charset="UTF-8" />
+        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+        <title>ChatStream-Octane</title>
+      <script type="module" crossorigin src="./assets/index-DZAT5HXC.js"></script>
+      <link rel="stylesheet" crossorigin href="./assets/index-DEIczM35.css">
+    </head>
+    <body>
+        <div id="root"></div>
+    </body>
+</html>

suites-experimental/chat-stream/dist/octane/octane-client-build.json

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+{
+  "version": 1,
+  "buildId": "EB1lFTf1277xlXhJ",
+  "mode": "production",
+  "capabilities": {
+    "independentHydration": false
+  }
+}

suites-experimental/chat-stream/dist/octane/resources.txt

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+assets/index-DEIczM35.css
+assets/index-DZAT5HXC.js
+assets/index-DZAT5HXC.js.map
+index.html
+octane-client-build.json