[ShahadatTest]

The change

After a TextIOWrapper read, reverse_iter_lines(..., preseek=False) starts at the underlying read-ahead cursor, often EOF, instead of the wrapper's logical position. Synchronize the wrapper with its own tell/seek cookie before reading its binary buffer.

Six regressions fail before the change; controls cover zero position and the default preseek behavior. Tests cover UTF-8 and translated CRLF newlines, partial lines and newline boundaries. This is independent of #633's JSONL relative-seek alignment and #649's block-size validation.

Validation on Windows:

• Python 3.12 full unit suite and module doctests: 783 passed, 1 skipped, 22 subtests passed in 6.34s.
• Python 3.10 focused regressions and affected module doctests: 9 passed in 0.11s.
• New-test Flake8, basic source error checks, Python 3.7 syntax parsing and diff checks pass. Other interpreter/platform matrices were not run.

The backstory

Earlier contribution: #665. This was found during source inspection and controlled local probes; no personal application use or human review is claimed.

AI assistance

• Harness/tooling: OpenAI Codex.
• Model: GPT-6.
• Original user prompt: new 20ta koro (make 20 new contributions). Codex investigated the bug, checked existing work and policies, implemented and tested the change, and prepared this PR.