[Bug] OsemosysClass.RYE() inserts a spurious empty dict for the 'EmisId' key, corrupting the emission parameter index

[tejassinghbhati]

Summary

OsemosysClass.RYE() in API/Classes/Case/OsemosysClass.py contains a structural logic error that causes a spurious 'EmisId': {} entry to be silently injected into the returned data structure on every call. This is a silent data-corruption bug — it produces no exception, but the malformed intermediate dict is immediately consumed by downstream methods (update_RYE in UpdateCaseClass.py and the OSeMOSYS solver input-file generators), potentially leading to missing emission parameter rows in the solver input or incorrect constraint generation.

What did you expect? (optional)

RYE() should return a dict keyed only by year strings (e.g. '2020', '2021'), matching the behaviour of every other pivot method in the class (RYT, RYC, RYS, RYTs, etc.). The 'EmisId' string is an index column — it should never appear as a year-level key in the output.

How can we reproduce it?

Run this directly in a PowerShell terminal from the repo root — no case or database needed:

@"
rye_raw = {'AnnualExogenousEmission': {'SC_0': [{'EmisId': 'CO2', '2020': 0.0, '2021': 0.5}]}}
RYE = {}
for param, obj1 in rye_raw.items():
    RYE[param] = {}
    for sc, array in obj1.items():
        RYE[param][sc] = {}
        for o in array:
            for year, val in o.items():
                if year not in RYE[param][sc]:
                    RYE[param][sc][year] = {}
                if year != 'EmisId':
                    RYE[param][sc][year][o['EmisId']] = val
keys = list(RYE['AnnualExogenousEmission']['SC_0'].keys())
print('Keys found:', keys)
print('Expected:  [2020, 2021]')
print('Bug confirmed:', 'EmisId' in RYE['AnnualExogenousEmission']['SC_0'])
"@ | python

Actual output:

Keys found: ['EmisId', '2020', '2021']
Expected:  [2020, 2021]
Bug confirmed: True

Root cause — inverted guard order in RYE() (lines 615–617):

# BUGGY (RYE) — dict init runs unconditionally, even for 'EmisId'
if year not in RYE[param][sc]:
    RYE[param][sc][year] = {}      # ← inserts 'EmisId': {} phantom entry
if (year != 'EmisId'):
    RYE[param][sc][year][o['EmisId']] = val

# CORRECT (all other methods e.g. RYT line 541, RYC line 601)
if (year != 'TechId'):             # ← guard FIRST
    if year not in RYT[param][sc]:
        RYT[param][sc][year] = {}
    RYT[param][sc][year][o['TechId']] = val

Running Select-String across the file confirms RYE is the only method with this inverted order — every other pivot method places the ID-key guard before the dict initialisation.

Environment (optional)

• Python 3.x
• Flask API (API/app.py)
• All platforms (Windows / Linux)
• Present on latest upstream main — OsemosysClass.py has no prior fix commits

Logs or screenshots (optional)

Related issue, PR, or discussion (optional)

No response

Proposed track

{"Track" => "Stability"}