[Bug] Codex VS Code Extension: "Error creating chat: unknown special value: ["bytes", {...}]" in Webview RPC deserializer

What version of the IDE extension are you using?

26.5901.22334

What subscription do you have?

ChatGPT Plus

Which IDE are you using?

VS Code

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

When attempting to resume or continue an existing chat in the Codex sidebar, the webview fails to load and displays this error banner:

Error creating chat: unknown special value: ["bytes", {"0": 123, "1": 10, "2": 32, "3": 32, "4": 34, ...}]

The conversation fails to open or accept further input.

What steps can reproduce the bug?

Steps:

1. Have an active Codex thread with changes or tool outputs that include byte buffers or serialized state (e.g. file content, audit records, or git state).
2. Close or restart the session.
3. Re-open or click "Continue" on the chat in the VS Code sidebar.
4. The webview crashes with: unknown special value: ["bytes", {"0": ...}].

Technical Root Cause:

In the extension's RPC transport (capn-rpc), UI is initialized with encodingLevel = "jsonCompatibleWithBytes".

When messages pass between the extension host and webview over VS Code's postMessage, JSON serialization turns Uint8Array buffers into plain JavaScript Objects with numeric keys ({ "0": byte, "1": byte, ... }).

In Ore.evaluateImpl under case "bytes":, the deserializer only checks:

• e[1] instanceof Uint8Array
• typeof e[1] === "string"

Because { "0": 123, ... } matches neither condition, it hits else break; and falls through to:
throw new TypeError('unknown special value: ' + JSON.stringify(e))

What is the expected behavior?

The chat session should load and continue normally without throwing an RPC deserialization error when the session history contains binary buffers or serialized state.

Additional information

Verified Fix

In both out/extension.js and the Webview bundle (webview/assets/app-initial-*.js) under case "bytes": (or case \bytes`:) in evaluateImpl`, adding support for plain object/array representations completely resolves the issue:

// Before:
case "bytes": {
    let s;
    if (e[1] instanceof Uint8Array) s = e[1];
    else if (typeof e[1] == "string") ...
    else break;
    ...
}

// After:
case "bytes": {
    let s;
    if (e[1] instanceof Uint8Array) s = e[1];
    else if (typeof e[1] == "string") ...
    else if (e[1] && typeof e[1] === "object")
        s = new Uint8Array(Array.isArray(e[1]) ? e[1] : Array.isArray(e[1].data) ? e[1].data : Object.values(e[1]));
    else break;
    ...
}

Start in out/extension.js and the webview/assets/app-initial-*.js bundles, at evaluateImpl's case "bytes" handling in the capn-rpc UI transport. Reproduce reopening a thread with serialized byte data, then verify both the extension and webview can deserialize the plain object or array representation and that the chat resumes without the error.