[HughRunyan]

What changed

AdvancedDSTCityRequest gains an optional other_landfills: a landfill spec (OtherLandfillsSpec) with no open or close years and no gate total. When it is given:

• Other landfills take the rest. Each year they take 1 minus the shares of the listed landfills open that year. A caller can state the sites it knows about and leave the rest, without making the shares add up to 1.
• A shut site's share goes to other landfills. In the years a listed landfill is shut (not yet open, or closed by its own dates or by a scenario's), its share goes to other landfills instead of being spread over the open ones.
• Over 1 is scaled down, not refused. A year whose open listed landfills claim more than 1 is scaled down to 1, and other landfills take nothing that year.
• landfills may be empty. landfill_split_timeline is required only when landfills lists any.

How: run_advanced_dst_city, run_advanced_dst_city_defaults and run_advanced_dst_city_limits each start by rewriting the request with other landfills listed as one more landfill (_with_other_landfills). That landfill opens with the model (1970, or a listed site's earlier opening) and never closes. Nothing downstream changes, so the run is the same, bit for bit, as one that lists that landfill at the leftover share. Other landfills come last in site_emissions, in the mass flow's sites and in the defaults.

Why: in the advanced DST's city mode, users have to make their site shares add up to 100%, or the frontend quietly scales them. WasteMAP's site list is incomplete, so most users can't name every site. With this, the WasteMAP frontend can send the shares users typed and let the model route the rest to "other landfills". The paired WasteMAP PR, RMI/WasteMAP#887, picks each city’s default type for other landfills and does the frontend work. Merge this one first.

User story: as an advanced DST user with data for a city and a few of its landfills, I want the waste I haven't assigned to go to a sensible default landfill, so that each site is modelled at the share I gave it and the city total still covers all of its waste.

Does this change a line marked # decision:?

• No
• Yes. A Climate TRACE pull request on the same branch name updates the entry:

Do model numbers change?

• No. Requests without other_landfills run exactly as before, and SWEET's full fast suite passes locally (596 tests).
• Yes. The PR is labelled model-output-change, and the changelog entry says how much they move.

Acceptance criteria

• With other_landfills, listed shares summing to 0.625 leave 0.375 to other landfills.
• A run with other landfills is bit-identical to one listing that landfill at the leftover share, checked on totals, per-site emissions and the mass flow.
• A listed site's share goes to other landfills in the years it is shut: before it opens, after it closes, and after a scenario closure in the scenario only.
• A year over 1 is scaled down, and other landfills take nothing that year.
• landfills: [] with other_landfills runs. Without other_landfills it is refused.
• Out-of-range listed shares are still refused. A pre-implement scenario row that the model discards is not.
• Without other_landfills, shares must still sum to ~1.
• run_advanced_dst_city_defaults and run_advanced_dst_city_limits take the same request.

Definition of done

• Acceptance criteria met
• Tests pass: tests/test_adst_city_other_landfills.py adds 18 tests
• Changelog updated
• Reviewed and merged

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

The request rewrite rejects empty scenario timelines instead of preserving the existing baseline fallback.

1 open issue

• Preserve baseline fallback for empty scenario mappings · New

What changed in this PR

Adds optional “other landfills” to city-level advanced DST, routing unassigned waste without requiring callers to provide a complete landfill list.

Changes:

• Rewrites requests to include a residual landfill across all three entry points.
• Adds routing, validation, and equivalence tests.
• Documents the new behavior in the changelog.

File	Description
tests/​test_adst_city_other_landfills.py	Tests residual routing and existing behavior compatibility.
SWEET_python/​advanced_dst_city.py	Adds the optional landfill specification and request rewrite.
changelog/​2026-10.md	Documents the feature and output ordering.

_{Review effort: Balanced}