[rwgk]

codex on behalf of Ralf:

Summary

Maintain both supported bindings majors on main, with short release branches for stabilization and urgent fixes. This PR supplies the ongoing development and release policy for the preceding packaging/CI layers.

• Distinguish major-line maintenance, which can include explicitly selected API/Python/platform compatibility work, from a frozen patch release accepting only approved fixes and prerequisites. Record the scope in the checklist and release notes.
• Keep routine CUDA 12 development in cuda_bindings_12/. The historical 12.9.x branch stays frozen except for emergency fixes using compatible historical tooling; reconcile those fixes back into main.
• Replace automatic historical-branch backports with a manual workflow taking one already merged PR and one existing non-default target branch. It opens a reviewable PR; normal CI approval and merging remain separate. Workflow-file backports and conflicting/generated adaptations need manual handling.
• Remove the active backport_branch setting with its last legacy consumer and remove automatic Dependabot updates to the frozen branch. The reader continues accepting that field in earlier schema-2 tagged registries. Default-branch Actions updates still cover both workflows and composite actions.
• Document release source/control revisions, exact-tag CI, dry-runs, component publication, owner publication of the shared GitHub Release draft, reconciliation, and version-selector ownership on main.
• Add maintenance/release-policy links to the package guidance and explicit development/review instructions for existing SYNCED blocks. The CUDA 12 generation guide, bidirectional root-review rule, and handwritten patch-transfer procedure are available earlier in cuda.bindings: configure independent CUDA 12 and CUDA 13 packages #3174.

Stack / Review Boundary

Previous: #3177. Next: #3182. The stack overview lists all six open PRs and the intended workflow.

#3174 through #3176 are intended to land together, with separate review scopes and cumulative CI at #3176; the first two are incomplete intermediate states. Release routing (#3177), maintenance policy (#3178), and the runtime fixes (#3182) follow that group. The complete proposed source tree is at #3182.

Baseline: main 03b4153574b3.

Suggested Review Order

1. .github/RELEASE-bindings.md
2. ci/README.md
3. .github/workflows/backport.yml
4. AGENTS.md

Counterpart Review

Inspected both package generation guides, the shared source-review rules, Core/metapackage release guidance, and all synchronized test-bootstrap/helper copies. The CUDA 12 policy records its frozen historical branch and reconciliation into the main-tree maintenance root; the current-major role remains defined by the registry. This layer changes policy/automation, not package runtime behavior.

The refresh also checks .github/dependabot.yml: retiring the frozen-branch entry retains default-branch coverage of both .github/workflows/ and .github/actions/*. The package counterparts remain cuda_bindings_12/AGENTS.md, cuda_bindings_13/AGENTS.md, and the shared release/maintenance guides; no package runtime behavior is added here.

Validation

Current local checks pass in full Git checkouts: 333 CI-tool tests at #3176, 346 at #3182, and 15 focused packaging tests. Full pre-commit run --all-files passes at both refreshed heads, including actionlint and Lychee. The tooling suite includes Git-based Pixi workspace discovery; it is not an archive-only suite. The local CUDA 13.4 TestVenv build and full QA run passed, covering Pathfinder, CUDA 13 bindings, PTDS, Cython interoperability, and Core. CUDA 12 native coverage is provided by the hosted matrix.

All three marked pytest-bootstrap blocks match byte-for-byte, and all four package-local shared-helper paths resolve to the same implementation. Tagged-source regressions retain compatibility with schema-2 registries containing the retired field.

Current hosted CI for the complete stack: run, attempt 3, at 341d286d865b012976898347c6728fda1e6c6a98 - passed, 105/105 jobs. This covers the cumulative stack and its runtime backports, rather than hosted release publication or backport execution.

One existing Windows Python 3.14t/Core row needed two failed-job retries: first for an access violation in incremental linking, then for a different graph-lifetime failure. Both cases passed on the final attempt and also passed at #3176; the affected Core sources are unchanged from main. No tests were skipped, serialized, or weakened for these retries. The graph failure remains a separate Core investigation; the passing retry does not establish that the suspected registry race is fixed.

The manual backport workflow and hosted release/publication procedure were not exercised against live target branches or package indexes. A retained maintenance milestone and removal of the temporary preview bootstrap remain follow-ups after the validated integration group lands. The lifecycle instructions now explicitly reserve preview versions across branches and cover minor-selector changes.

Checklist

• Relevant existing and focused regression tests cover the integration behavior.
• This description identifies the layer's scope and validation boundary.

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[rwgk]

/ok to test 9cf3778

[github-actions]

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[rwgk]

/ok to test fb5cced