Data and code supporting "Why the Cap-Ferret sand spit is collapsing" (v1.3)

Reproducibility bundle for Gasque (2026), Why the Cap-Ferret sand spit is collapsing — an integrated energetic framework for sudden collapses and long-term dune stability at Lège-Cap-Ferret (SW France) (preprint v1.3, EarthArXiv). Contents (~3 MB zipped, ~5 MB unpacked, organised in 6 folders PJ1–PJ6): PJ1 — 11 high-resolution figures (PNG, 150 dpi): EGMS PS-InSAR maps and time-series, H/V Nakamura spectra at FR.LRVF and ATE, ERA5 storm-sequence pre-conditioning before the 2019-10-21 event, situation map of 8 sites and 2 seismic stations. PJ2 — Raw analytical outputs (JSON + CSV): H/V results for the 2026-01-29 event (12,094 windows), 12-window dry-vs-wet H/V comparison, 8-site EGMS triangulation velocities, three replication tests on the 2019-10-21 event. PJ3 — Python analysis scripts (vectorised H/V Nakamura, EGMS seasonal analysis, 8-site control triangulation, 2019 replication) with README and dependencies. PJ4 — Execution log for audit. PJ5 — Written annex listing 10 data sources and 13 peer-reviewed references. PJ6 — Index of consulted source reports (BRGM RP-68730-FR, SLGBC, Artelia, CEREMA, GIP Littoral); third-party PDFs are not redistributed (copyright); URLs provided. Reproducibility: Python 3.10+, dependencies listed in PJ3/README.md. All upstream inputs are public (Copernicus EGMS, RESIF/EPOS-FR FR.LRVF station, IOC Arcachon-Eyrac tide gauge, ERA5/ECMWF, Hub'Eau, BSS BRGM). A SHA256SUMS.txt file at the bundle root provides bit-level integrity verification (sha256sum -c SHA256SUMS.txt). License: CC-BY 4.0 for figures, data, and written content. Scripts in PJ3 are released under the same terms; see PJ3/README.md. Funding: none. Research conducted on personal time and personal resources.