[MaxGhenis]

Rewrites Microcosm's Belgian country package from its never-built BE-SILC design to the donor-transport design. Belgium becomes the second country on build/transport/, after New Zealand (decision d048). The package stays inactive: no transport_graph.json, receipt contract, rule bindings or scenarios yet.

What changes in build/be/

• Donor: the same pinned populace-us Build P artifact NZ uses. Repository, revision, filename, size (462,915,783 bytes) and SHA-256 are copied exactly from build/nz/, in both the JSON and the typed projections.
• Placeholders: the Chronicle consumer artifact and the rulespec-be tree are declared as unpinned references, following NZ's inactive-spec conventions. No placeholder hashes.
• Spine: one US donor channel with assigned Belgian geography. No observed-region channel.
• Vintages: donor 2024, target/policy year 2026 and geography NIS 2025. The 2026 year is method card BE-MC0, which is pending Max's ruling (d1902), and the description says so.
• Geography: households draw NIS 2025 communes nationally, from the commune population package in Add Statbel commune population facts for NIS 2025 chronicle#383. Province, region and community are declared derived layers.
• Release contract: private policyengine/populace-be-private, with no public artifacts. The SILC licence language is replaced by the Microcosm-BE provenance line (synthetic population, US survey donor pool reweighted). Publication stays Max's decision.
• Catalogs: non-monetary columns only. Monetary columns wait for a shared EUR unit.
• Target references: the SILC survey-year and offset fields are removed. These are still inactive groundwork; source periods and selectors are unchanged, and replacing them (with ageing to 2026) is later work.
• SILC residue: rg -ni silc build/be returns nothing.

Shared files (cleared with the NZ hub before push)

• country_spec.py: one new branch in the Belgian-only _attest_be_typed_geography_compatibility (~1939), whose single call site is gated on declared_country == "be". It accepts an empty observed-region constraint only with a <level>_nationally draw and no source_nuts1_preserved claim. The legacy observed-region path still requires preservation, and a new BE test proves it.
• tests/engine_free/shared/test_country_spec.py: only TestBelgianPackage and TestCountryStagePlan change, both Belgian-only (stage renames and the new donor/geography contract). The one negative-case change, "province" → "district", exists because province is now a declared Belgian layer.
• tests/engine_free/shared/test_spec_engine_country_bundles.py: Belgian assertions only. No NZ assertion changed, and Add NZ G8-r1 target references, ERP bridge and d1376 gates #1362's NZ resource additions are intact.
• tests/golden/be_country_spec.json: regenerated with the test's own helpers. It's the only golden that changed.
• There is no diff in build/nz/, build/transport/ or tools/ci_test_plan.py.

Checks (each file run separately on this branch)

File	Result
test_spec_engine_country_bundles.py	22 passed
test_country_spec.py	137 passed, NZ golden byte-equal
test_nz_spec_package.py	1,192 passed
test_spec_only_country_packages.py	8 passed

Ruff lint and format pass, and git diff --check is clean. An independent GPT-6.1 Sol review approved c68994f with one docstring nit, which is fixed in dc157a7 (see the review comment).

🤖 Generated with Claude Code

[MaxGhenis]

Independent review: GPT-6.1 Sol, APPROVE_WITH_NITS at c68994f (~/reviews/belgium-2026-10-12/transport-port/jobs/b1/review-c68994f2.md).

What the review checked:

• Donor identity: the BE and NZ donor objects match exactly across the JSON and typed YAML (repository, revision, filename, size, SHA-256). There are no fabricated placeholder pins.
• Loader branch: it's Belgian-only, and the observed-region path is unchanged. Seven in-memory attester cases passed.
• Goldens: only the BE golden changed, and the repository's own helpers reproduced all three byte for byte.
• Status: the package stays inactive, every release artifact stays private, and 2026 is marked as pending d1902.
• CI plan: verification passed across 764 test files.

The one finding was a P3: the module docstring in country_spec.py still described "BE-SILC source stages". It's fixed in dc157a7, a docstring-only change. After the fix, test_country_spec.py and test_spec_engine_country_bundles.py pass: 159 tests.

Merge is pinned to head dc157a7 and gated on green checks and MERGEABLE.

[MaxGhenis]

Held until 2026-10-29 12:00Z. Do not merge before then.

The UK hub asked for this hold, and the NZ hub is holding microcosm#1375 to the same date for the same reason. Both kernels below hash the source bytes of country_spec.py (source_hash, microcosm-graph kernel.py):

• targets.compile@1 and targets.problem@1 take it through _COMPILE_MODULES (target_kernels.py:408–418).
• The gate kernel takes it at gate_kernels.py:726.

So this PR changes their implementation hashes for every country. UK outputs don't change, but every cached UK graph node would recompute during the Budget window:

• María's Monday cut and its certification (about 12:00Z on 10/26);
• budget-final-regen (10/27);
• Budget day (10/28).

Belgium doesn't need this before then. The PR is back to draft so no sweep merges it. It will be re-checked and merged on green at reviewed head dc157a7 after 10/29 12:00Z.