# Analysis Stall Fix Design

## Problem

The summary analysis appears to stall after logging a matched WeChat issue. The
analysis thread is still running, but it provides no progress while scanning
rules or checking article URLs. Deleted-article checks are performed serially,
with a 10-second timeout per unique URL. Repeated clicks can also start multiple
analysis threads.

## Design

Keep the existing matching behavior and change only task execution and
observability:

- Check unique WeChat article URLs with a bounded pool of eight workers.
- Limit each URL request to three seconds.
- Treat timeout and network errors as "unknown" and retain the analysis result.
- Cache each unique URL result so duplicate matches are checked once.
- Report rule-scanning progress and URL-checking progress through a callback.
- Forward progress messages from `AnaThread` to the existing log signal.
- Disable the analysis button while work is active and restore it when the
  thread finishes, including after exceptions.
- Ignore attempts to start analysis while an existing analysis thread is
  running.

## Error Handling

An unavailable article URL must not remove a finding. Only a successful response
containing the existing deleted-content marker removes matching rows. Exceptions
remain contained in the worker thread and are reported through the application
log.

## Testing

Add unit tests that verify:

- Duplicate URLs are fetched only once under concurrent execution.
- Deleted rows are removed while normal and failed requests are retained.
- Progress callbacks reach their final totals.
- Analysis progress callbacks are emitted during rule scanning.

Run the complete existing unit-test suite with the bundled Python runtime.