sdst honors the caller-supplied gas flaring efficiency

[HughRunyan]

City.sdst_v1_5 declared a new_landfill_flaring parameter but never read it. Its flaring block referenced an undefined bare name flaring, and the resulting NameError was swallowed by a bare except that forced flare destruction efficiency to a hardcoded 0.98. The flaring efficiency forwarded by WasteMAP's /v1/site_emissions/sdst_v1_5 endpoint — the /sdst "Gas flaring efficiency" control — therefore never affected results.

Environment

• Component: SWEET_python/city_params.py, City.sdst_v1_5
• Consumer: WasteMAP backend /v1/site_emissions/sdst_v1_5 (backend/sweet_launch.py), which passes its flaring Body param as new_landfill_flaring=flaring
• Affected since: the parameter was introduced; the newer adst path is not affected

Reproduction

Call /v1/site_emissions/sdst_v1_5 twice with gas capture on (so there is captured methane to flare), changing only the flaring efficiency:

• gas_efficiencies: {"baseline": [0.75], "scenario": [0.75]}
• run A → flaring: {"baseline": [0.0], "scenario": [0.0]} (no flaring)
• run B → flaring: {"baseline": [0.98], "scenario": [0.98]} (full flaring)

Expected vs actual

Summed total emissions across all modeled years:

flaring efficiency	before (actual)	after (expected)
0.0 — no flaring	6648.34	23422.34
0.98 — full flaring	6648.34	6648.34

Actual (before): both runs return an identical 6648.34 — the input is discarded and flaring is always 0.98.
Expected (after): no flaring produces materially higher emissions, since captured methane is vented rather than destroyed.

Root cause

# Check if flaring is defined as a variable
try:
    flaring_series_baseline = pd.Series(flaring["baseline"], index=years)   # NameError
    ...
except:                                                                     # swallows it
    flaring_series_baseline = pd.Series(0.98, index=years)                  # always taken

flaring is not defined in this scope; the method's parameter is new_landfill_flaring. Every call took the except branch.

The fix

Read new_landfill_flaring[scenario_key][0] (sdst models a single landfill, index 0), fall back to DEFAULT_FLARE_EFFICIENCY only when no value is supplied, and drop the bare except so genuine errors surface instead of silently degrading to a default.

Acceptance criteria

• City.sdst_v1_5 reads the caller-supplied new_landfill_flaring for both baseline and scenario.
• The scenario value is spliced in from implement_year onward; the baseline value applies before it.
• When no flaring is supplied (None), behaviour is unchanged: DEFAULT_FLARE_EFFICIENCY (0.98).
• No bare except masking errors in this block.
• Verified end-to-end through the WasteMAP endpoint (numbers above); red→green confirmed by reverting the fix.
• Changelog entry added under Fixed, flagged as a model-output change.
• Existing SWEET_python tests pass (86 passed); WasteMAP fast backend suite passes (55 passed).

Model-output change

Labelled model-output-change, not breaking-change: nothing stops running and no data contract changes. Any /sdst run that set a non-0.98 flaring efficiency with gas capture on will now return different — correct — numbers. Runs that left flaring at the default are unchanged, as are all adst runs.

Notes for the reviewer

• Paired WasteMAP PR (regression test + backend changelog): RMI/WasteMAP#725. That branch has the same name, so WasteMAP CI installs this branch and exercises the fix.
• backend/requirements.txt tracks SWEET_python main unpinned, so WasteMAP picks this up automatically once merged — no pin bump needed.
• ⚠️ Changelog conflict with WP-419 adst callers can set site depth and override the decomposition rate (k) #40: that PR also adds changelog/2026-08.md and a changelog/README.md entry. Whichever merges second should combine the two — WP-419 adst callers can set site depth and override the decomposition rate (k) #40's entry is under Added, this one is under Fixed, so they slot together without rewording.

Definition of Done

• Acceptance criteria met
• Tests and checks pass
• Docs/changelog updated
• Reviewed and merged

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