fix: remove lru_cache memory leak in Repository.is_git_repo

[AI-God-Dev]

fix: remove lru_cache memory leak in Repository.is_git_repo

Fixes #4210

• Replace @lru_cache decorator with instance variable caching
• Prevents memory leaks from cached self references
• Maintains same O(1) performance characteristics
• Add comprehensive tests for memory leak prevention and cache verification
• Remove unused lru_cache import

The @lru_cache decorator on instance methods causes memory leaks because
the cache holds references to self, preventing garbage collection. I found
this issue with a TODO comment acknowledging the problem but no fix.

My solution uses instance-level caching (self._is_git_repo_cache) which
provides the same performance benefit without the memory leak.

This affects anyone running long-lived processes or automation scripts that
repeatedly check git repos. The memory leak is gradual but adds up over time.

Closes #4210

---

Note

Fix memory leak in Repository.is_git_repo

• Replace @lru_cache with per-instance _is_git_repo_cache to avoid retaining self and reduce subprocess calls
• Initialize and use _is_git_repo_cache in Repository.__init__/is_git_repo; behavior remains unchanged
• Add tests: instance GC verification, per-instance cache isolation, and cache usage checks
• Remove unused lru_cache import

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[cursor]

Tests register insufficient subprocess calls for multiple instances

Medium Severity

The new tests test_cache_is_per_instance and test_repository_instances_are_garbage_collected only register subprocess commands once, but attempt to create multiple Repository instances. Each Repository.__init__ calls is_git_installed(), is_git_repo(), and fetch(), consuming 3 subprocess registrations. The first test creates 2 instances (needs 6 registrations), and the second creates 100 instances (needs 300 registrations), but both only register 3. Following the existing test patterns (e.g., test_is_synced_when_synced registers duplicate commands), each call consumes its registration. These tests will fail when pytest-subprocess finds no matching registration for the second instance.

🔬 Verification Test

Why verification test was not possible: The tests would require running pytest with the pytest-subprocess plugin installed in the project's test environment. The bug is evident from comparing the new tests against existing test patterns in the same file - test_is_synced_when_synced explicitly registers the same command twice because is_synced() calls status() twice, demonstrating that each fp.register() call is consumed once. The new tests fail to follow this established pattern when creating multiple Repository instances.

Additional Locations (1)

• lib/crewai/tests/cli/test_git.py#L107-L129