In `@crates/stdlib/src/ssl/compat.rs`:
- Around line 1687-1788: ssl_write currently always calls writer.write_all(data)
which appends plaintext to rustls on every retry, causing duplicate application
data; add a per-socket flag on PySSLSocket (e.g., plaintext_buffered_for_write)
that ssl_write sets the first time it writes the given data (after calling
writer.write_all) and skips subsequent writer.write_all calls when that flag is
true, still proceeding to flush_pending_tls_output/send_all_bytes and handle
WANT_READ/WANT_WRITE; clear the flag once conn.wants_write() is false and after
the final flush_pending_tls_output completes (so future ssl_write calls will
write new plaintext again); update logic in ssl_write to consult this flag
(respecting is_bio mode) and ensure the flag is cleared on successful completion
or on errors that indicate the buffered plaintext was consumed or should be
discarded.

In `@crates/stdlib/src/ssl/compat.rs`:
- Around line 1787-1812: The timeout arm in the match on send_all_bytes
currently clears the buffered write state leading to duplicate plaintext
re-buffering on retry; modify the SslError::Timeout branch to behave like
WantWrite/WantRead by returning Err(SslError::Timeout) without clearing
socket.write_buffered_len (so pending_tls_output remains intact) and preserve
the existing semantics for is_bio vs socket-mode handling; locate the match in
the write path around send_all_bytes and update the Timeout case to not reset
write_buffered_len so retries won’t duplicate sends.
- Around line 1738-1759: Add a hash guard to detect retries with different
content: add a write_buffered_hash: PyMutex<Option<u64>> field to PySSLSocket
and initialize it to None in both PySSLSocket constructors; when you buffer new
plaintext in the block that currently sets *socket.write_buffered_len.lock() =
data.len(), compute a stable u64 hash of data and store it in
socket.write_buffered_hash.lock(); update the retry check to require both the
length and the stored hash to match (i.e., treat it as a bad write retry if
already_buffered != data.len() || buffered_hash != Some(data_hash)); and when
you clear the buffer state (where you set *socket.write_buffered_len.lock() = 0)
also clear socket.write_buffered_hash to None.