bazel

Bazel Monorepos

Make build changes against the actual target graph and pinned Bazel/ruleset versions. Examples cover Bazel 9.2.0; they are not an upgrade instruction. The user's explicit instructions take precedence over this skill's guidelines.

Establish the relevant context

Use the affected targets, error output, or requested build outcome as input. Check .bazelversion, relevant module declarations, BUILD files, and the configuration involved in the task. Read other repository configuration only when it affects that question.

Question	Tool
Target dependencies, reverse dependencies, paths	bazel query
Selected flags, platforms, toolchains, or select() branches	bazel cquery with the failing invocation's configuration
Actual commands, inputs, outputs, tools	bazel aquery
External modules, versions, generated repositories	bazel mod
Cache misses or execution performance	Execution logs, profiles, BEP

If the failing target or invocation cannot be inferred, ask for it and continue independent inspection. Do not invent repository pins or remote-cache endpoints.

Preserve the build contract

• Declare direct inputs, dependencies, tools, and runtime data on the owning target. Use runfiles APIs for runtime resources.
• Keep package boundaries and visibility deliberate. Neither one target per file nor one per service is a universal template.
• For Bazel 9, use Bzlmod and explicit external language-rule loads. For older repositories, follow version-matched rules until an upgrade is requested.
• Diagnose missing inputs or configuration differences before using clean --expunge or disabling sandboxing; those can hide the cause.
• Validate affected targets and configurations. Reserve graph-wide builds/tests for graph-wide impact or required repository checks.

Deliver the requested patch or diagnosis with relevant target labels, evidence, and unresolved configuration dependencies. Finish checks needed for that outcome without expanding a local fix into a repository migration.

References

Load only the topic needed; use section headings within longer references.

Task	Reference
Packages, labels, dependencies, visibility, BUILD style	BUILD-GRAPH.md
Modules, extensions, lockfiles, overrides, WORKSPACE migration	BZLMOD.md
rc files, selects, platforms, toolchains, transitions	CONFIGURATION.md
Query syntax and build failure diagnosis	QUERIES-DEBUGGING.md
Sandboxing, runfiles, caching, remote execution	HERMETICITY-CACHING.md
CI gates, affected targets, profiles, performance	CI-PERFORMANCE.md
Macros, rules, providers, aspects, repository rules	STARLARK.md
Requested adoption or repository consolidation	ADOPTION.md
Compact command or label lookup	CHEATSHEET.md

Use version-matched Bazel docs, ruleset release notes, and the Bazel Central Registry when bundled guidance does not establish compatibility.