Published release exports can no longer serve as --base-h5: QBI input reconciliation requires base-only PUF columns

Found during the Build K staging run (2026-07-13). Fail-closed catch #3 of 3 — this one is structural, not feed drift.

What happened

Passing the published Build J export (populace_us_2024.h5, sha 9d1e460d…) as --base-h5 fails at with_us_qbi_input_reconciliation (release tool, unconditional since the QBI/SOI wiring): it requires 15 PUF-imputed columns (business_is_sstb, w2_wages_from_qualified_business, unadjusted_basis_qualified_property, …) that only exist on the 337k base produced by build_us_puf_support_base.py — the release export's column surface never carried them.

Why it matters

--base-h5 documents itself as "Existing Populace US H5 to recalibrate. Defaults to HF latest." That default path — recalibrate the published artifact — now fails unconditionally, since HF latest is a release export. Anyone without a base h5 is blocked; until 2026-07-13 the base existed only on the build machine (now mitigated: populace-us-staging carries bases/build-j/… with a MANIFEST, and #406's checkpointed base builder makes rebuilds feasible).

Options

1. Carry the 15 QBI columns in release exports (they are person-level inputs; cost is export width).
2. Make the reconciliation conditional on the columns being present, with a loud gate downgrade recorded in the manifest when absent (weakens the SSTB identity guarantee — probably wrong).
3. Keep it hard, but fix the --base-h5 help text and fail with a message that names the staging bases/ path — recalibration simply requires a base, not an export.

(3) is the minimal truth-telling fix; (1) is the one that restores the "recalibrate HF latest" default.

🤖 Generated with Claude Code

Start with the --base-h5 handling and the with_us_qbi_input_reconciliation entry point, then inspect build_us_puf_support_base.py and the published export path. Reproduce the Build K failure using the published Build J export and compare its columns with the staging base under bases/build-j/. Done means the chosen compatibility or messaging behavior is implemented and the recalibration path reports the required outcome clearly.