Code/content compatibility matrix

Forward and backward compatibility between running code (GHCR image / git tag) and on-disk corpus (artifacts produced by some prior pipeline run). Update this file on every release.

Related: GitHub #796 (system contract: produced_by, /api/health preflight), GitHub #797 (operator framework + smoke script), PROD_RUNBOOK — Code/content compatibility, Corpus artifacts and viewer surfaces.

Code version	Min corpus version it can read	Max corpus version it can read	Notes
2.6.1	2.4.0	2.6.x	Operator compatibility framework (#797): PROD_RUNBOOK section, CORPUS_ARTIFACTS_AND_SURFACES.md, post_deploy_smoke.sh, this matrix. No new required artifact fields.
2.6.0	2.4.0	2.6.x	First release with corpus-level produced_by stamp (#796). GIL 2.0 / KG 1.2 read via migration helpers. Rollback to 2.5.x still supported when corpus was not mutated by 2.6-only writers.
2.5.0	2.4.0	2.6.0	corpus_manifest schema 1.1 (cost_rollup, PR #650). Older manifests still load with defaults.
2.4.0	2.0.0	2.5.x	RFC-072 canonical GI/KG identity (GIL 2.0, KG 1.2 finalized).

How to update on release

1. Add a row for the version you are tagging.
2. State min corpus semver the new code still reads cleanly.
3. State max corpus semver you have tested (usually the same minor line).
4. Note rollback window: which prior code tag remains safe after this corpus may have been touched.
5. Run make pre-release — it fails if the current pyproject.toml version is missing from this file.