Replication Archive and Audit Trail for: Contestability Precedes Greening — Single-Bidding in High-Carbon Public Procurement

Version 2 of the replication archive, fully reanalysed and re-titled. The earlier version (Governance Reform Unlocks Decarbonization Dead Zones) was rebuilt after a critical desk review; this version corrects the data and retracts the claims that did not survive scrutiny.

Corrections and audit (see Reanalysis_and_Audit_Trail_v2.zip):

• A corrupted/over-ingested 2018 TED vintage (~25x official contract-award-notice counts) is documented and reconciled; headline results are stable when it is excluded.
• 54.8% of contracts carried an unusable supplier identifier (placeholder string "nan"); supplier analyses are re-run on valid identifiers only.
• The carbon premium is a between-sector composition statistic with Moulton-correct (cluster-robust) inference, not a measured emissions effect.
• RETRACTED: the regression-discontinuity "first stage" (collapses under legally correct year-specific, buyer-type-specific cutoffs); the +65.3% measured-emissions claim (a facility-size artifact, null within size strata); and the governance-gradient reading of the premium (a pre-registered test gives rho=+0.33, the wrong sign).
• SURVIVING result: a not-yet-treated, coverage-stable difference-in-differences finds transparency reform reduced single-bidding by ~9 to 17 pp (cohort-timing permutation p<=0.06).

Contents: corrected manuscript and Supplementary Information (LaTeX + PDF), reanalysis/audit scripts and their JSON outputs, point-by-point response memos, and the original 12.7 GB Data.zip carried over from v1. Code MIT; data derivatives CC-BY-4.0.