fix(serialization): serialize enums by declared value

[gaoanze888]

Related issue

Fixes #7652

Summary

to_serializable() serialized plain Enum values through the repr() fallback, corrupting Flow outputs and trace fields (for example "<Status.OK: 'ok'>" instead of "ok"), and enum dictionary keys became unstable strings containing id(). Enums now expand to their declared .value before the primitive check, and _to_serializable_key() does the same for keys.

Tests cover plain Enum, IntEnum, date-valued and tuple-valued enums, direct to_string() entry, and enum dictionary keys.

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Verification

• Tests added or updated for the changed behavior
• Relevant tests and quality checks pass locally

PYTHONPATH=lib/crewai/src:lib/crewai-core/src \
  ../crewAI-contrib/.venv/bin/pytest \
  lib/crewai/tests/utilities/test_serialization.py -q -n 0 -o addopts=''
# 27 passed

../crewAI-contrib/.venv/bin/ruff check <changed files>
../crewAI-contrib/.venv/bin/ruff format --check <changed files>
../crewAI-contrib/.venv/bin/python -m compileall -q <changed files>
git diff --check

Mutation check: restoring upstream serialization.py makes both new enum tests fail (repr strings and unstable keys reappear).

Notes on scope and compatibility:

• Enum expansion passes the same _current_depth, so it behaves as a transparent wrapper; the unified depth cutoff behavior is unchanged.
• The remaining failures in lib/crewai/tests/utilities/ (optional anthropic/litellm/lancedb/crewai_files provider tests) are identical on pristine main and are unrelated to this change.

Additional context

Historical context: closed unmerged PR #5180 included a similar enum fix inside a broad tracing rework; this change extracts only the enum contract.

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📒 Files selected for processing (2)

• lib/crewai/src/crewai/utilities/serialization.py
• lib/crewai/tests/utilities/test_serialization.py

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

• lib/crewai/tests/utilities/test_serialization.py

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📝 Walkthrough

Walkthrough

The shared serializer now uses declared enum values for enum dictionary keys. Non-primitive key values use stable JSON strings. Tests cover string, integer, date, tuple, and dictionary-key serialization.

Changes

Enum serialization

Layer / File(s)	Summary
Serializer enum-key handling lib/crewai/src/crewai/utilities/serialization.py	_to_serializable_key serializes enum values before stringification. Primitive results use str; non-primitive results use json.dumps.
Enum serialization tests lib/crewai/tests/utilities/test_serialization.py	Tests define string-, integer-, date-, and tuple-valued enums. Tests verify enum values and dictionary keys use their declared values.

Priority: ➖ Normal

Severity of issue fixed: Medium

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: serializing enums by their declared values.
Description check	✅ Passed	The description includes the related issue, a clear summary, verification steps, test coverage, scope notes, compatibility details, and additional context.
Linked Issues check	✅ Passed	Issue #7652 requires enum values to serialize to their declared .value and enum keys to produce deterministic strings. to_serializable() unwraps Enum before primitive handling and recursively se…
Out of Scope Changes check	✅ Passed	The changes are limited to enum-key handling in the shared serializer and focused serialization tests. The changes directly implement issue #7652 and do not demonstrate unrelated behavior.

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Actionable comments posted: 1

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Inline comments:
In `@lib/crewai/src/crewai/utilities/serialization.py`:
- Line 135: Update _to_serializable_key so non-primitive enum values are passed
through to_serializable and converted to a deterministic string, using stable
JSON for list or dictionary results instead of object identity. Add assertions
covering the date-valued and tuple-valued enum cases, while preserving existing
primitive enum-key behavior.

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Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 68cf2dc7-a8ae-4f44-a28a-da5898a81655

📥 Commits

Reviewing files that changed from the base of the PR and between 0374c63 and 44cc867.

📒 Files selected for processing (2)

• lib/crewai/src/crewai/utilities/serialization.py
• lib/crewai/tests/utilities/test_serialization.py

Included review availability: Your plan provides up to 10 included reviews per hour; 9 remain after this review.