Fix NameError crash on arrow keys in interactive review

[VIVAAN-DHAWAN]

Why

Running the interactive review on any PR crashes the moment an arrow key is pressed:

File "diffly_cli/cli.py", line 410, in interactive_view
    sequence = _read_escape_sequence()
NameError: name '_read_escape_sequence' is not defined

The redesigned interactive menu (v1.0.0) calls _read_escape_sequence() to read the bytes following an Escape keypress, but the helper was never defined — so ↑/↓ navigation, one of the two primary controls shown in the menu footer, is guaranteed to crash after the user has already waited for the full analysis. Reproduced on macOS (Python 3.14) reviewing #12.

What users will see / Surface area

• src/diffly_cli/cli.py: defines _read_escape_sequence(). It uses select.select() with a short timeout to drain the CSI bytes that follow Escape ([A for ↑, [B for ↓), so:
  • Arrow keys move the cursor again.
  • A lone Escape press returns an empty sequence instead of blocking the loop (preserving the v1.0.0 fix documented in the changelog).
  • Read/OS errors degrade to an empty sequence rather than crashing.
• No behavior change outside the interactive menu; JSON, Markdown, wizard, and local mode are untouched.

Validation

• New regression tests in tests/test_regressions.py:
  • test_interactive_menu_handles_arrow_keys_without_crashing drives the real interactive_view loop over a pty with ↑ ↓ Enter keypresses — this exact test fails with NameError on main.
  • test_escape_sequence_reader_returns_arrow_codes asserts [A is returned when those bytes follow Escape.
  • test_escape_sequence_reader_treats_a_lone_escape_as_empty asserts a quiet input yields "" without hanging.
• Full suite: pytest -q → 56 passed.
• Duplicate check: no open PRs or issues cover this crash; the bug is present on current main (0e9cf1d).

[github-actions]

Diffly verdict: QUARANTINE

#14 · 3 files · 81 lines changed · checks: PENDING

Risk flags: NO_TEST_COVERAGE (low), CHECKS_PENDING (medium)

Risk flags and reasoning

• NO_TEST_COVERAGE (low): Changed production files have no obvious neighboring or repository test coverage; this is a review hint, not a verdict gate. — src/diffly_cli/cli.py
• CHECKS_PENDING (medium): Required status checks are still pending. — combined commit status; diffly; test (3.10); test (3.12); test (3.13)
• QUARANTINE because required checks are still running.

Blast-radius summary

File	Change	Symbols	Direct callers	Tests
CHANGELOG.md	+4/-0	<top-level changes>	—	—
src/diffly_cli/cli.py	+22/-0	<top-level changes>	—	—
tests/test_regressions.py	+55/-0	<top-level changes>	—	—

Deterministic triage is authoritative; any optional LLM explanation cannot change the verdict.