fix: restrict observability logging suggestion to Python only

[chundawat-h]

Description

This PR resolves a cross-language suggestion leakage bug where the Python-specific print/observability rule (SUGGESTION 7: Logging) was running for all programming languages. This caused the analyzer to suggest Python-specific code snippets (like import logging and logger.info()) in reports for other languages like Java and C++.

Related Issue

Fixes #156

Key changes:

• Restricted the logging/observability print check in backend/app/services/code_assistant.py to only run when language == "Python".
• Added a robust unit test case test_suggestions_observability_print_only_python() in backend/tests/test_endpoints.py to assert that Observability suggestions are not generated for Java but function correctly for Python.

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor

Testing

• I ran backend tests ($env:RATE_LIMIT_PER_MINUTE=100; python -m pytest -v passes with all 40 tests green)
• I tested frontend behavior manually (verified locally that Java print statements no longer show Python logging suggestions)

Checklist

• I have read CONTRIBUTING.md
• My branch is up to date with main
• I have run pytest -v and all tests pass
• I have not introduced duplicate issues or features
• My PR title follows the format: feat/fix/docs/test: short description
• I have added tests for new features (Level 2 and 3 issues)
• No hardcoded secrets or API keys in my code
• This PR is linked to a GSSoC 2026 issue

Test evidence

$env:RATE_LIMIT_PER_MINUTE=100; python -m pytest -v
====================================== test session starts ======================================
platform win32 -- Python 3.13.3, pytest-9.0.3, pluggy-1.6.0 -- C:\Python313\python.exe
cachedir: .pytest_cache
rootdir: D:\deta\Desktop\OpenSourceProjects\New folder\AI-dev-assistant\backend
plugins: anyio-4.13.0, asyncio-1.3.0
asyncio: mode=Mode.STRICT, debug=False, asyncio_default_fixture_loop_scope=None, asyncio_default_test_loop_scope=function
collected 52 items

tests/test_endpoints.py::test_root PASSED [ 1%]
tests/test_endpoints.py::test_health PASSED [ 3%]
tests/test_endpoints.py::test_rate_limit_headers_on_success_response PASSED [ 5%]
tests/test_endpoints.py::test_rate_limit_returns_429_with_retry_after_header PASSED [ 7%]
tests/test_endpoints.py::test_explanation_python PASSED [ 9%]
tests/test_endpoints.py::test_explanation_no_language_hint PASSED [ 11%]
tests/test_endpoints.py::test_explanation_rust PASSED [ 13%]
tests/test_endpoints.py::test_explanation_detects_rust_without_hint PASSED [ 15%]
tests/test_endpoints.py::test_explanation_accepts_rust_hint_alias PASSED [ 17%]
tests/test_endpoints.py::test_explanation_empty_code PASSED [ 19%]
tests/test_endpoints.py::test_explanation_too_long PASSED [ 21%]
tests/test_endpoints.py::test_explanation_typescript PASSED [ 23%]
tests/test_endpoints.py::test_explanation_java PASSED [ 25%]
tests/test_endpoints.py::test_explanation_cpp PASSED [ 26%]
tests/test_endpoints.py::test_explanation_cyclomatic_fields_present PASSED [ 28%]
tests/test_endpoints.py::test_explanation_cyclomatic_simple PASSED [ 30%]
tests/test_endpoints.py::test_explanation_cyclomatic_moderate PASSED [ 32%]
tests/test_endpoints.py::test_explanation_cyclomatic_high PASSED [ 34%]
tests/test_endpoints.py::test_explanation_cyclomatic_very_high PASSED [ 36%]
tests/test_endpoints.py::test_debug_detects_zero_division PASSED [ 38%]
tests/test_endpoints.py::test_debug_detects_hardcoded_secret PASSED [ 40%]
tests/test_endpoints.py::test_debug_detects_bare_except PASSED [ 42%]
tests/test_endpoints.py::test_debug_detects_eval PASSED [ 44%]
tests/test_endpoints.py::test_debug_clean_code PASSED [ 46%]
tests/test_endpoints.py::test_debug_javascript PASSED [ 48%]
tests/test_endpoints.py::test_debug_java PASSED [ 50%]
tests/test_endpoints.py::test_debug_cpp PASSED [ 51%]
tests/test_endpoints.py::test_explanation_php PASSED [ 53%]
tests/test_endpoints.py::test_explanation_detects_php_without_hint PASSED [ 55%]
tests/test_endpoints.py::test_debug_php PASSED [ 57%]
tests/test_endpoints.py::test_debug_php_buggy_patterns PASSED [ 59%]
tests/test_endpoints.py::test_debug_rust PASSED [ 61%]
tests/test_endpoints.py::test_debug_rust_buggy_patterns PASSED [ 63%]
tests/test_endpoints.py::test_debug_kotlin PASSED [ 65%]
tests/test_endpoints.py::test_debug_issue_has_required_fields PASSED [ 67%]
tests/test_endpoints.py::test_js_ts_security_patterns PASSED [ 69%]
tests/test_endpoints.py::test_suggestions_returns_score PASSED [ 71%]
tests/test_endpoints.py::test_suggestions_perfect_score PASSED [ 73%]
tests/test_endpoints.py::test_suggestions_observability_print_only_python PASSED [ 75%]
tests/test_endpoints.py::test_full_analyze PASSED [ 76%]
tests/test_endpoints.py::test_full_analyze_all_languages PASSED [ 78%]
tests/test_endpoints.py::test_missing_code_field PASSED [ 80%]
tests/test_endpoints.py::test_unicode_code PASSED [ 82%]
tests/test_endpoints.py::test_single_line_code PASSED [ 84%]
tests/test_ping.py::test_ping PASSED [ 86%]
tests/test_python_ast_analyzer.py::test_detects_missing_bracket_syntax_error PASSED [ 88%]
tests/test_python_ast_analyzer.py::test_detects_invalid_indentation_syntax_error PASSED [ 90%]
tests/test_python_ast_analyzer.py::test_detects_division_by_zero_expression PASSED [ 92%]
tests/test_python_ast_analyzer.py::test_detects_division_by_zero_inside_function_call PASSED [ 94%]
tests/test_python_ast_analyzer.py::test_detects_out_of_range_list_index PASSED [ 96%]
tests/test_python_ast_analyzer.py::test_detects_out_of_range_string_index PASSED [ 98%]
tests/test_python_ast_analyzer.py::test_detects_string_integer_concatenation PASSED [100%]

====================================== 52 passed in 1.56s =======================================