Fix mutable default arguments in core and plugins

[stef41]

Summary

14 function signatures across 9 files use mutable default arguments (=[], ={}), which is a well-known Python anti-pattern. Mutable defaults are evaluated once at function definition time and shared across all calls, so data from one invocation can silently persist into subsequent calls.

This is particularly concerning in the AI reasoning interfaces where _reasoning_plugins={}, _learner_plugins={}, and _planner_plugins={} are shared across instances, and in diagnosis.py where used_mnemonics=[] accumulates state across recursive walkdown() calls.

Changes

Replaced mutable defaults with None and added initialization guards in:

Component	Files	Fixes
onair/src/ai_components/	2	2
onair/src/reasoning/	2	3
onair/src/systems/	2	4
plugins/	3	5

All modified files pass python -m py_compile.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 65.78947% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.91%. Comparing base (16fe993) to head (fba1ba2).
⚠️ Report is 162 commits behind head on main.

Files with missing lines	Patch %	Lines
plugins/csv_output/csv_output_plugin.py	20.00%	2 Missing and 2 partials ⚠️
plugins/reporter/reporter_plugin.py	20.00%	2 Missing and 2 partials ⚠️
onair/src/reasoning/diagnosis.py	33.33%	1 Missing and 1 partial ⚠️
plugins/generic/generic_plugin.py	60.00%	0 Missing and 2 partials ⚠️
onair/src/systems/vehicle_rep.py	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main     #194      +/-   ##
===========================================
- Coverage   100.00%   98.91%   -1.09%     
===========================================
  Files           26       31       +5     
  Lines          970     1198     +228     
  Branches       136      182      +46     
===========================================
+ Hits           970     1185     +215     
- Misses           0        5       +5     
- Partials         0        8       +8     

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[the-other-james]

Thanks for this pull request! I'll read up more on the link you included...
In the meantime, can you please create an issue and submit a contributors license agreement? Refer to the Contributing section in the readme.
Thank you!

[stef41]

Thanks @the-other-james! I have created issue #197 for this fix.

I will download the Individual CLA, complete it, and email it to gsfc-softwarerequest@mail.nasa.gov with james.marshall-1@nasa.gov CCed as described in the contributing guide. I will follow up here once that is done.