buildfix-edit

Edit engine for buildfix plans.

This crate applies planned operations, checks preconditions, enforces safety gates at apply time, and produces patch previews.

Key APIs

• attach_preconditions(...): add SHA256 file preconditions (and optional git HEAD precondition)
• preview_patch(...): render unified diff without writing files
• apply_plan(...): execute plan in dry-run or write mode and return BuildfixApply
• check_policy_block(...): detect policy-block outcomes for exit-code mapping
• apply_op_to_content(...): pure operation-to-content transform
• execute_plan_from_contents(...): apply ops using in-memory content maps

Supported op shapes

• toml_set
• toml_remove
• toml_transform (rule-based transforms)
• text_replace_anchored

Built-in transform rules

• ensure_workspace_resolver_v2
• set_package_rust_version
• set_package_edition
• ensure_path_dep_has_version
• ensure_workspace_dependency_version
• use_workspace_dependency

Policy and safety behavior

• safe ops run by default when --apply is set
• guarded ops require allow_guarded
• unsafe ops require allow_unsafe
• Missing params and precondition mismatches block apply results

This is a support crate for the buildfix workspace and may evolve in lockstep with the workspace release train.