feat: add tuple preservation to AutoSerializer and 'pythonic' alias

[27Bslash6]

Summary

• AutoSerializer now preserves tuples through serialization roundtrips (matching existing set/frozenset/datetime/UUID preservation)
• Add serializer='pythonic' as a registry alias for 'auto'

Why

AutoSerializer preserved sets and frozensets via type markers but not tuples — inconsistent. The tricky part: msgpack natively serializes tuples as arrays (so the default callback is never called). Fixed by pre-processing tuples into {"__tuple__": True, "value": [...]} markers before encoding.

Test plan

• Tuple roundtrip (simple, nested, mixed with sets/datetimes)
• get_serializer('pythonic') returns AutoSerializer
• 1405 unit tests pass
• Lint + type check clean

Closes #78

Summary by CodeRabbit

• New Features

  • Added a "pythonic" serializer alias that uses the same integrity-checking behavior as core serializers.

• Bug Fixes

  • Tuple support added to serialization: tuples (including nested, empty, single-element, and when nested in lists/dicts) are preserved through roundtrips; malformed tuple markers now raise serialization errors.

• Tests / Documentation

  • Tests and docs updated to cover tuple handling and the "pythonic" alias.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between db3583e and 5512b36.

📒 Files selected for processing (1)

• tests/unit/test_auto_serializer_new_types.py

🚧 Files skipped from review as they are similar to previous changes (1)

• tests/unit/test_auto_serializer_new_types.py

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📝 Walkthrough

Walkthrough

AutoSerializer now preserves tuples by wrapping them as explicit tuple markers before MessagePack packing and reconstructs them on unpacking. The serializer registry gains a "pythonic" alias mapped to AutoSerializer and instantiated with integrity checking like other core serializers.

Changes

AutoSerializer Tuple Preservation & Pythonic Alias

Layer / File(s)	Summary
Pythonic serializer alias registration src/cachekit/serializers/__init__.py	SERIALIZER_REGISTRY adds the "pythonic": AutoSerializer entry and get_serializer includes "pythonic" in the integrity-checking instantiation branch; tests verify the alias returns an AutoSerializer.
Tuple serialization and deserialization src/cachekit/serializers/auto_serializer.py, tests/unit/test_auto_serializer_new_types.py	Added _wrap_tuples to convert tuples (including nested) into {"__tuple__": True, "value": [...]} before msgpack.packb; extended _auto_object_hook to validate and reconstruct tuples; documentation/error messages and tests updated to cover tuple roundtrips and malformed marker errors.

🎯 3 (Moderate) | ⏱️ ~20 minutes

"I'm a rabbit with a tiny pen,
Tuples hop back safe again.
Wrapped in markers snug and bright,
Pythonic alias joins the flight.
Hooray — roundtrips sleep at night!" 🐇

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	Description covers Summary, Motivation, and Test Plan but is missing the Type of Change checkbox selection and most Security/Documentation/Testing/Backward Compatibility checklists required by template.	Complete the required template sections: select Type of Change, verify Security Checklist items, confirm Testing checklist, and document Backward Compatibility assessment.
Docstring Coverage	⚠️ Warning	Docstring coverage is 61.11% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title accurately summarizes the two main changes: tuple preservation in AutoSerializer and addition of 'pythonic' alias, both clearly related to the changeset.
Linked Issues check	✅ Passed	All code changes fully address linked issue #78 objectives: tuple preservation via type markers is implemented, 'pythonic' alias is registered, and comprehensive tests verify both features.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to the linked issue: registry alias addition, tuple marker serialization/deserialization logic, and comprehensive tuple-focused tests. No extraneous modifications detected.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/pythonic-serializer-tuple

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

tests/unit/test_auto_serializer_new_types.py (1)

564-646: 💤 Low value

Consider adding single-element tuple test.

Single-element tuples like (1,) are a common Python edge case. While the current implementation likely handles them correctly, adding a test would provide explicit coverage for this pattern.

📝 Optional test to add

def test_single_element_tuple_roundtrip(self):
    """Single-element tuples preserve the trailing comma semantics."""
    serializer = AutoSerializer()
    data = (1,)
    serialized, metadata = serializer.serialize(data)
    result = serializer.deserialize(serialized, metadata)
    assert isinstance(result, tuple)
    assert len(result) == 1
    assert result == (1,)

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@tests/unit/test_auto_serializer_new_types.py` around lines 564 - 646, Add a
new unit test method test_single_element_tuple_roundtrip to the
TestAutoSerializerTuple class that constructs serializer = AutoSerializer(),
sets data = (1,), calls serializer.serialize(data) and
serializer.deserialize(serialized, metadata), and asserts the result is a tuple,
has length 1, and equals (1,); this provides explicit coverage for
single-element tuple semantics alongside the existing tuple tests.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@tests/unit/test_auto_serializer_new_types.py`:
- Around line 629-645: Update the two tests
test_malformed_tuple_marker_missing_value and
test_malformed_tuple_marker_wrong_value_type to remove the unnecessary
enable_integrity_checking=False argument when instantiating AutoSerializer; the
tuple validation runs in _auto_object_hook during msgpack deserialization and is
independent of ByteStorage integrity/compression, so change "serializer =
AutoSerializer(enable_integrity_checking=False)" to "serializer =
AutoSerializer()" in both tests to match the pattern used by other
corruption/roundtrip tests.

---

Nitpick comments:
In `@tests/unit/test_auto_serializer_new_types.py`:
- Around line 564-646: Add a new unit test method
test_single_element_tuple_roundtrip to the TestAutoSerializerTuple class that
constructs serializer = AutoSerializer(), sets data = (1,), calls
serializer.serialize(data) and serializer.deserialize(serialized, metadata), and
asserts the result is a tuple, has length 1, and equals (1,); this provides
explicit coverage for single-element tuple semantics alongside the existing
tuple tests.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 769641c7-1a80-44b6-8b25-77931f52380b

📥 Commits

Reviewing files that changed from the base of the PR and between 67f37d2 and db3583e.

📒 Files selected for processing (2)

• src/cachekit/serializers/auto_serializer.py
• tests/unit/test_auto_serializer_new_types.py

🚧 Files skipped from review as they are similar to previous changes (1)

• src/cachekit/serializers/auto_serializer.py