[Web UI] loadSessionTranscript fails with ZodError on 2.5.2; terminal session open recovers it #4742

Bug summary

After upgrading Kimi Code CLI to 2.5.2, the Web UI showed multiple session/transcript rendering and loading problems. The connection status remained connected, but loading an existing session could fail with a Zod validation error. In addition, the Web UI did not reliably display chat messages, and previously created sessions were missing from or not displayed in the Web UI session list.

The same session could still be opened successfully from the terminal UI. After opening the affected session in the terminal and then returning to the Web UI, that session started loading again. This suggests a Web UI transcript-loading / session-list synchronization or state-recovery issue rather than a generally inaccessible session.

Environment

• Kimi Code CLI: 2.5.2
• Installation: npm global
• OS/runtime: Android 10 using Termux
• Web UI: local Kimi Web UI in a browser
• Browser/version: not recorded

Symptoms observed

1. Existing sessions are not reliably listed in the Web UI. Older sessions that already exist locally may not appear in the Web UI session list, making them unavailable to open from the browser interface.
2. Chat messages are not reliably rendered. The Web UI may show a blank conversation or fail to display messages, even though the session can be opened from the terminal UI.
3. Transcript loading fails. Opening an existing session can fail during loadSessionTranscript with the Zod validation error below, while the connection still reports connected.
4. New chat messages may not appear. In one test, a new chat was opened and a simple message was sent, but the message did not appear in the UI and no useful error was shown.
5. Terminal workaround. Opening the affected session in the terminal UI, then returning to the Web UI and reopening it, made the session load and display normally in our test.

These symptoms were observed during the same troubleshooting session. It is not yet confirmed whether they share one root cause.

Diagnostic error

Operation: loadSessionTranscript
Connection: connected
Error type: ZodError

[
  {
    "expected": "number",
    "code": "invalid_type",
    "path": ["items", 5, "steps", 0, "usage", "inputCacheRead"],
    "message": "Invalid input"
  },
  {
    "expected": "array",
    "code": "invalid_type",
    "path": ["tasks"],
    "message": "Invalid input"
  },
  {
    "expected": "object",
    "code": "invalid_type",
    "path": ["meta"],
    "message": "Invalid input"
  }
]

The session ID and local timestamp are intentionally omitted.

Steps observed

1. Upgrade Kimi Code from 2.4.0 to 2.5.2 using the npm global installation.
2. Open the local Web UI.
3. Notice that older existing sessions are not reliably displayed in the Web UI session list.
4. Open an existing session when available. The Web UI may fail while loading its transcript, with the Zod error above.
5. Open a new chat in the Web UI and send a simple message. In one observed case, the message did not appear and the UI showed no useful error.
6. Open the affected session from the terminal UI. The session opens and works there.
7. Return to the Web UI and open the session again. It then loads and displays normally in our test.

Expected behavior

• The Web UI should list previously created sessions that are available to the CLI.
• Opening a session should load and render its conversation messages reliably.
• New messages should appear in the conversation, or the UI should show a clear actionable error if sending/loading fails.
• The Web UI should correctly parse the transcript payload returned by the server. If the payload is invalid or incompatible, it should show a useful error and provide a recovery path rather than leaving the chat blank or silently failing.

Actual behavior

• Older sessions may be absent from the Web UI session list.
• Conversation messages may not render, leaving the chat blank or incomplete.
• Transcript parsing can fail with a ZodError even while the connection status is connected.
• Opening the same session through the terminal UI appears to refresh/reconcile the state sufficiently for the Web UI to load it afterward.

Additional notes

• The terminal UI was able to open the same session, so the session data was not wholly inaccessible.
• These observations may point to transcript schema compatibility, session-list synchronization, or Web UI state management affected by the recent update. The exact root cause is unknown.
• A related but not identical Web UI rendering report exists in [Web UI] First user message bubble missing / messages misordered & duplicated in live rendering; server transcript is correct #3991. This report documents the additional session-list and message-rendering symptoms alongside a concrete transcript schema validation failure observed on 2.5.2.

Please let me know if additional logs or a sanitized transcript payload would help investigate.