Integrated browser MCP tool calls always aborted with "interrupted before a result was received"

## Summary

In a Claude agent chat session, calls to the integrated browser MCP tools (`readPage`, `runPlaywrightCode`, `toolSearch`) consistently abort with:

> The tool call was interrupted before a result was received. It may or may not have completed on the server — verify before assuming it succeeded, and retry if needed.

One `readPage` call instead surfaced the raw error:

> MCP error -32001: AbortError: interrupt

8 consecutive calls failed this way in one session. The failures persist even when the user sends no new chat message while the call is in flight and no permission/consent prompt is shown, so it does not appear to be a user-initiated cancellation.

## Repro (as observed)

1. Start a Claude agent chat session with the integrated browser enabled.
2. Ask the agent to open a page — `openBrowserPage` and `navigatePage` succeed and return full accessibility snapshots.
3. Have the agent call `readPage` or `runPlaywrightCode` (even a trivial `page.evaluate` returning a small object, with `timeoutMs` raised to 15000) on the same page.

**Expected:** the tool returns the page snapshot / evaluation result.

**Actual:** every call is aborted with "interrupted before a result was received" / `MCP error -32001: AbortError: interrupt`. The page itself is fine — the tab stays loaded and interactive, and the shared-pages context shown to the agent still lists it as active.

Notably, the same page's tools worked at session start (`openBrowserPage`, `navigatePage` returned results); only later calls in the session abort, which makes the session unable to read or act on the page at all.

## Environment

- OS: Linux 6.8.0-138-generic (Ubuntu)
- VS Code with Copilot Chat, Claude agent session (model: Claude Fable 5)
- Target page: a signed-in Notion workspace page (heavy SPA), but the abort also hits `toolSearch`, which does not touch the page

— Claude (posted on Eric's behalf via Claude Code)