Replace Tissot-centric CNG cookbook with tool-agnostic per-format validation sections

[Copilot]

Community feedback: a standalone Tissot cookbook reads as tool docs, not format guidance. The CNG Formats Guide needs validation content woven into existing format pages, not a separate Tissot how-to.

Deleted

• cng-cookbook-contribution.qmd — Tissot-first cookbook

Added

• cng-format-validation-sections.qmd — three self-contained sections, each ready to PR into its corresponding CNG guide format page (before "Further Reading")

Section structure (consistent across all three):

concept → why it matters → how to verify → how to fix

Section 1 — Validating Your FlatGeobuf

• Spatial index: packed Hilbert R-tree, detect via ogrinfo/Fiona, fix with ogr2ogr -lco SPATIAL_INDEX=YES
• CRS metadata: no WGS 84 default, assign vs. reproject (-a_srs / -t_srs)
• FlatGeobuf vs. GeoParquet decision table

Section 2 — Validating Your GeoParquet

• geo metadata key: required for spec compliance, verify with pyarrow.parquet.read_metadata(), fix via GeoPandas re-write
• CRS encoding: PROJJSON required; detect WKT1/missing programmatically
• Compression: zstd recommended (50–70% reduction); inspect per-column codec, re-write with compression="zstd"
• Bbox columns: row-group spatial pruning, how to check presence

Section 3 — Validating Your Shapefile Before Migration

• Multi-file integrity: required (.shp, .shx, .dbf) vs. recommended (.prj, .cpg), consequences of each missing file, Python completeness check
• 2 GB limit: silent truncation risk, size check + feature-count cross-validation via ogrinfo

Conventions

• Tool-agnostic throughout (ogrinfo, stdlib Python, GeoPandas)
• Tissot referenced only as a "See also" link inside the HTML contributor note — not in any substantive section
• Contributor note at bottom covers placement, heading-level adjustment, and cross-reference handling for individual page PRs

Original prompt

Read cng-cookbook-contribution.qmd in the repo root.
This file needs to be completely rewritten. Community feedback on the CNG Formats Guide said a standalone Tissot cookbook reads as tool documentation, not format guidance. They want per-format validation sections woven into existing format pages instead.
Replace cng-cookbook-contribution.qmd with cng-format-validation-sections.qmd that contains three separate validation sections, each designed to be PR’d into the corresponding format page in the CNG guide (https://guide.cloudnativegeo.org/).
Use Quarto markdown (.qmd) format. Each section should have a clear heading like “Validating Your FlatGeobuf” that could slot into the end of an existing format page.
Section 1: FlatGeobuf Validation
∙ Spatial index: explain that FlatGeobuf optionally includes a packed Hilbert R-tree. Without it, spatial queries require full file scan. Show how to verify with ogrinfo and Python (fiona). Show how to regenerate with ogr2ogr -lco SPATIAL_INDEX=YES.
∙ CRS metadata: explain it’s stored in the header, doesn’t default to WGS 84. Show how to verify with ogrinfo. Show how to assign with ogr2ogr -a_srs.
∙ When to choose FlatGeobuf vs GeoParquet: spatial queries and streaming → FlatGeobuf. Columnar filtering and analytics → GeoParquet.
Section 2: GeoParquet Validation
∙ Geo metadata: explain the required geo metadata key in Parquet schema metadata (JSON with geometry column, CRS as PROJJSON, geometry types). Show how to verify with pyarrow.parquet.read_metadata(). Show how to fix with geopandas re-write.
∙ CRS encoding: should be PROJJSON per spec. Flag WKT1 or missing CRS.
∙ Compression: recommend zstd for best compression/speed tradeoff (50-70% reduction). Show how to check codec per column with pyarrow. Show how to re-write with compression.
∙ Bounding box column: explain optional bbox columns enable row-group-level spatial filtering. Show how to check if present.
∙ When to choose GeoParquet vs FlatGeobuf.
Section 3: Shapefile Validation Before Migration
∙ Multi-file integrity: list required files (.shp, .shx, .dbf) and recommended (.prj, .cpg). Explain what goes wrong when each is missing (no CRS, corrupted encoding). Show a quick completeness check.
∙ 2GB file size limit: explain silent truncation risk.
Conventions
∙ Concepts first, then why it matters, then how to verify, then how to fix
∙ Tool-agnostic where possible (ogrinfo, Python standard libraries)
∙ Do NOT make Tissot the primary validation method — the guide must be tool-agnostic
∙ Tissot can appear as a “See also” link at the very end, nothing more
∙ Add a contributor note at the bottom explaining these are designed to slot into existing format pages before their “Further Reading” sections
Also delete the old cng-cookbook-contribution.qmd if it still exists after creating the new file

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