Shared metadata and Git input

FlowDelta and FlexiPageDelta keep their product policies and semantic pipelines separate, but they share the boundary that reads metadata from disk or Git. This boundary is intentionally small: it owns external Git execution, metadata-at-a-ref reads, and Git path discovery. It does not know how a Flow or FlexiPage is parsed, diffed, rendered, or reported.

Modules

Module	Responsibility
`src/io/read-metadata.ts`	Read an XML file synchronously or read a metadata path with `git show <ref>:<path>`.
`src/io/git.ts`	Provide the default synchronous Git adapter, the injectable `GitRunner` port, and missing-at-ref error classification.
`src/io/discover-git-metadata.ts`	Discover metadata paths from both refs or from the changed-path diff, normalize separators, apply the supported matcher, and return sorted unique paths.

Reader contract

readMetadataFromFile(path) requires an .xml path, reports a missing local file as an error, and returns the file contents as UTF-8 text.

readMetadataFromGit(repo, ref, filePath) returns the XML text from git -C <repo> show <ref>:<filePath>. A path that is absent at that ref returns null; unrelated Git failures are rethrown. The product pipeline uses null to construct its own empty model for added or deleted metadata.

Both Git-facing functions accept the small GitRunner port in tests. The default adapter remains the only place that calls execFileSync("git", ...).

Discovery contract

discoverGitMetadataFiles({ repo, fromRef, toRef, pattern, changedOnly }) uses the following rules:

Full-tree mode lists files from both refs and unions them, so additions and deletions remain visible.
changedOnly mode uses git diff --name-only --diff-filter=ACMRD <from> <to> -- <pattern> before applying the same matcher.
Git path separators are normalized to /; results are de-duplicated and sorted deterministically.
Supported patterns are literal paths, * within one path segment, ** across path segments, and ? for one non-separator character. Brackets and other glob syntax are literal characters; no general glob dependency is used.

The product CLIs retain their own argument policy. Flow Git mode still requires --path, while FlexiPage Git mode defaults to force-app/**/*.flexipage-meta.xml when --path is omitted. They also retain their own parsers, empty-model factories, artifact naming, summaries, and per-file error/exit-code handling.

Tests and change boundaries

test/metadata-io.test.ts is the shared contract suite. It covers matching, normalization, union and changed-only discovery, deterministic output, and missing-versus-unrelated Git errors. Product-level Git tests remain in test/semantic-diff.test.ts and test/flexipage-delta.test.ts, including each CLI’s path policy.

Changes to this boundary should preserve the separate product pipelines and should not expand glob syntax, alter Salesforce org retrieval, or add a runtime dependency.