[MaxGhenis]

Finish the Microcosm rename while preserving certified release identifiers and existing public imports.

Counts

Counts compare origin/main (57b5870) with the completed branch HEAD. Mentions are case-insensitive occurrences from git grep -I -i -o populace; filenames alone are not mentions.

	Files	Mentions
Before	63	914
After	58	833

The classification TSV preserves and corrects the earlier lane's rows and now covers every original occurrence: 56 P, 70 C, 1 D, 709 R and 78 H. Another 45 rows explicitly identify new HEAD occurrences: 42 compatibility names/markers and 3 frozen producer-label assertions. Original rows use origin/main line numbers; new rows use completed HEAD line numbers.

What changed

• Updated live documentation, docstrings, comments, CLI help, example output and the current package-name example to Microcosm. Renamed test helpers, test descriptions, test constants and synthetic temporary filenames.
• Introduced MicrocosmBelgiumDataset, MicrocosmDataProducerCertificationStrategy and MICROCOSM_* source constants. Updated internal references and preserved every prior public import with a marked alias.
• Made the Belgium example prefer MICROCOSM_BE_DATASET, with a lazy fallback to the prior environment variable. Added regression tests for public imports, producer labels and environment precedence.
• The complete branch holds 7734c12 (initial prose rename), 2cfd72a (changelog fragment), ca1b1bf (restore the required hosting link), 7b1f29f (finish code/prose renames and add compatibility coverage), and 06d7897 (fragment text).

Left as is

Category	Remaining mentions	Reason
R	712	Published HF repositories, release IDs, dataset keys, artifact filenames, package metadata, serialized producer labels and matching code/tests. Includes all 88 manifest mentions and all 11 bundle TRACE mentions. No dataset-key aliases were added.
H	78	70 released changelog occurrences, 6 occurrences in the dated TRACE case study, and 2 historical public runbook-link paths retained for existing links.
D	1	README calibration URL remains on its existing Vercel hosting address per the host's explicit instruction until the policyengine.org route is live.
C compatibility	42	Marked source aliases and tests that exercise them, including their required removal comments.

No actionable P or unaliased C occurrences remain. No mapping line was added. The certified manifest, TRACE sidecars, released changelog and JSON/JCS evidence fixtures are byte-identical to origin/main (39 files checked).

Compat aliases

All aliases are marked compat: populace alias, remove after 6.16.1. Release 6.16.1 is the next release inferred by .github/bump_version.py from the existing .changed.md fragment.

Prior name	Current name	Location	Remove after
PopulaceBelgiumDataset	MicrocosmBelgiumDataset	policyengine.tax_benefit_models.be, .be.datasets, .be.model; package __all__	6.16.1
PopulaceDataProducerCertificationStrategy	MicrocosmDataProducerCertificationStrategy	policyengine.provenance.certification	6.16.1
POPULACE_US_SOURCE_COVERAGE_FILE	MICROCOSM_US_SOURCE_COVERAGE_FILE	policyengine.provenance.certification	6.16.1
POPULACE_DATA_PACKAGES	MICROCOSM_DATA_PACKAGES	policyengine.provenance.certification	6.16.1
POPULACE_RELEASE_REPOS	MICROCOSM_RELEASE_REPOS	policyengine.provenance.certification	6.16.1
POPULACE_US_2024_ACS_LOCAL_BUILD_O	MICROCOSM_US_2024_ACS_LOCAL_BUILD_O	policyengine.tax_benefit_models.us.legacy_spm.registry	6.16.1
POPULACE_US_2024_ACS_LOCAL_MICROCOSM_1263	MICROCOSM_US_2024_ACS_LOCAL_MICROCOSM_1263	policyengine.tax_benefit_models.us.legacy_spm.registry	6.16.1
POPULACE_BE_DATASET	MICROCOSM_BE_DATASET	examples/belgium_axiom_pilot.py; new environment variable wins	6.16.1

The CLI value --data-producer populace is R, because it is written into certified manifests. It remains unchanged rather than becoming a new dataset/producer alias.

Tests

All pytest runs were serial; at most two pytest runners ran concurrently. Completed focused selections recorded 487 passing tests and 4 optional skips. The access and timeout failures below also reproduce on the unchanged baseline. The normal 18-file regression command below was interrupted twice before collection completed because pinned country-model initialization spent several minutes recursively importing US variable modules and loading parameter YAML. These are incomplete checks, not test passes. A retry using only POLICYENGINE_SKIP_COUNTRY_IMPORTS=1 also stopped during country fixture imports; focused runs use --noconftest as well and tests with self-contained fixtures.

.venv/bin/python -m pytest tests/test_certify_data_release.py tests/test_us_legacy_spm.py tests/test_us_legacy_spm_integration.py tests/test_us_legacy_inputs_integration.py tests/test_release_manifests.py tests/test_dataset_materialization.py tests/test_dataset_source.py tests/test_dataset_runtime.py tests/test_trace_tro.py tests/test_release_tro_generation.py tests/test_release_build_folders.py tests/test_uk_qualification_pipeline.py tests/test_execution_receipt.py tests/test_bundle.py tests/test_bundle_metadata.py tests/test_entity_utils.py tests/test_us_regions.py tests/test_uk_regions.py -q

• Installed all extras using UV_CACHE_DIR=/private/tmp/policyengine-rename-uv-cache UV_PYTHON_INSTALL_DIR=/private/tmp/policyengine-rename-uv-python uv sync --all-extras: passed in about 4 minutes. The initial default-cache attempt was denied by the workspace sandbox; retrying with a writable cache succeeded. Dependency pins and lockfile are unchanged.
• POLICYENGINE_SKIP_COUNTRY_IMPORTS=1 .venv/bin/python -m pytest --noconftest tests/test_microcosm_compatibility.py tests/test_be_axiom_pilot.py -k 'not registry' -q: 25 passed, 4 optional source-stack tests skipped, 2 registry cases deselected; the actual registry module was validated separately below.
• POLICYENGINE_SKIP_COUNTRY_IMPORTS=1 .venv/bin/python -m pytest --noconftest tests/test_dataset_materialization.py tests/test_dataset_source.py tests/test_bundle.py -q: 41 passed.
• POLICYENGINE_SKIP_COUNTRY_IMPORTS=1 .venv/bin/python -m pytest --noconftest tests/test_certify_data_release.py tests/test_release_build_folders.py tests/test_uk_qualification_pipeline.py tests/test_trace_tro.py tests/test_release_tro_generation.py tests/test_bundle_metadata.py -k 'not test_preparation_generates_new_sidecars_and_verifies_the_exact_pair and not test_the_real_cli_generates_replay_requests_despite_country_import_suppression' -q --tb=short: 421 passed, 1 failed, 5 deselected. The remaining failure, test_the_certification_environment_falls_back_to_the_packaged_certificate, exceeded its unchanged 60-second subprocess timeout. The same test reproduced the identical timeout on the isolated origin/main archive (1 failed, 225.68 seconds), confirming the issue predates this branch. All 70 certification, 80 release-folder, 46 TRACE, 40 TRO-generation and 7 bundle-metadata tests passed, together with 178 UK qualification cases. The five excluded cases are the four private-HF variants and slow real CLI case described below.
• The earlier lane's python -m pytest tests/test_entity_utils.py tests/test_us_regions.py -q failed because the package was not installed; the completion run installed the full development environment before retrying checks.
• Lightweight registry check with .venv/bin/python and runpy.run_path: both aliases retain object identity, full serialized source records match origin/main, and registry/hash lookups return the same objects. This avoids initializing the entire country model.
• Ruff lint and format checks on all changed Python files: passed.
• AST/syntax checks on all changed Python files: passed.
• git diff --check: passed.
• Classification multiset comparison against origin/main: exactly 914 baseline occurrences, no missing/extra rows; all 45 added HEAD occurrences match their current file/line/token.
• An initial certification/qualification/TRACE selection passed 168 tests and failed 4 parameterized preparation cases before its real CLI case was interrupted. All four failures hit HTTP 401 fetching policyengine/policyengine-uk-data-private release metadata. One representative failure reproduced identically on an isolated origin/main archive (57b5870, 1 failed), confirming pre-existing private-repository access requirements.
• Byte comparisons against origin/main: all 39 frozen artifact/changelog files passed.

Host follow-ups (ca1b1bf, 06d7897)

• README.md:10: the calibration dashboard link stays on its Vercel address until its policyengine.org route is
  live, under Max's link rule (ca1b1bf).
• changelog.d/microcosm-name-sweep-20261106.changed.md: the fragment now names what this PR renames and the
  aliases' last release (06d7897). Its generic text had said "throughout docs, comments and code". The changed
  type makes bump_version.py cut a patch release, 6.16.1, which matches the aliases' remove after 6.16.1 markers.

Unsure

• examples/belgium_axiom_pilot.py:22: retained populace_be_pilot_2026.h5 as R conservatively. The example refers to an existing pilot input artifact; this sweep has no evidence that its on-disk basename changed. The environment-variable name and surrounding prose are renamed.

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Sweep record and rulebook: ~/reviews/populace-rename-2026-11-06/ (RULEBOOK.md).

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