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name: bazel-central-registry description: Work with Bazel Central Registry (BCR) modules and bzlmod dependencies. Use for finding modules/versions in a BCR checkout, checking latest BCR versions, upgrading bazel_dep entries in MODULE.bazel (including includes), and analyzing dependency trees via the bundled scripts/bcr_tool.py and upstream scripts/registry.py.

Bazel Central Registry

Overview

Use this skill to query BCR module metadata, update bzlmod dependencies, and inspect dependency trees. The skill bundles the upstream registry.py helper and a thin CLI (bcr_tool.py) that wraps common workflows.

Quick start

• List direct deps from a workspace (follows include() chains):
  • python3 scripts/bcr_tool.py list-deps --module-file /path/to/MODULE.bazel
• Check latest versions from BCR:
  • python3 scripts/bcr_tool.py latest --module rules_go --module rules_python
• Dry-run upgrade (print diffs only):
  • python3 scripts/bcr_tool.py upgrade --module-file /path/to/MODULE.bazel
• Apply upgrade edits:
  • python3 scripts/bcr_tool.py upgrade --module-file /path/to/MODULE.bazel --write
• Best-effort dependency tree (bounded depth):
  • python3 scripts/bcr_tool.py deps-tree --module-file /path/to/MODULE.bazel --max-depth 2

Tasks

Find modules / versions (local registry clone)

1. Clone or point at a local bazel-central-registry checkout.
2. Search by substring:
   • python3 scripts/bcr_tool.py find --registry-path /path/to/bazel-central-registry --query rules_
3. List versions for a module:
   • python3 scripts/bcr_tool.py list-versions --registry-path /path/to/bazel-central-registry --module rules_go

Upgrade modules in MODULE.bazel

• upgrade reads the root MODULE.bazel, follows include() files, and updates bazel_dep(..., version = "...") entries to the latest BCR version.
• Use --module to target a subset and --include-overrides to update single_version_override entries.
• Always start with a dry-run, then re-run with --write when the diff looks correct.

Analyze dependency tree

• list-deps shows direct deps (names + versions) from all included module files.
• deps-tree fetches MODULE.bazel files from BCR for a best-effort transitive tree (bounded by --max-depth).
• For a fully resolved graph (including overrides/extensions), run Bazel directly:
  • bazel mod graph

Resources

scripts/

• registry.py: upstream BCR registry helper (used for metadata and downloads).
• bcr_tool.py: CLI wrapper for module search, latest version lookup, upgrades, and dependency inspection.