Module merge 

Manifest-with-global-index merge per ADR-020 §4.

Given a global index (GlobalIndex) and a per-project manifest (ProjectManifest), the merge function produces a single resolved view per declared path: which entry “wins”, which fields came from the manifest’s [overrides] block, and what the final metadata is.

Precedence

For each path mentioned in the manifest’s required or optional list, the resolver applies precedence rules straight from ADR-020 §4:

1. If the path appears as [secret."<path>"] in the manifest, its metadata is read from the manifest only — the path is project-local.
2. Otherwise, metadata is read from the global index. If the manifest has an [overrides."<path>"] block, the listed behavioural fields override the index values.
3. If a path appears in required / optional and exists in neither the global index nor as [secret."..."], the merge fails with MergeError::UnknownPath — the E_SECRET_UNKNOWN_PATH error from the ADR.

E_OVERRIDE_FIELD_NOT_ALLOWED (the ADR’s name for “you tried to override a non-behavioural field”) is already enforced at parse time by deny_unknown_fields on OverrideEntry — it surfaces through ManifestError::Parse during loading, not here.

Warnings (advisory)

The merge also emits non-fatal warnings, returned alongside the resolved view. doctor consumes them; the loader itself accepts the manifest. Cases:

• MergeWarningKind::NoOpOverride — an [overrides] field is set to the same value as the global. The override is harmless but adds noise; suggest removal.
• MergeWarningKind::OverrideForUndeclaredPath — an [overrides."x"] block exists for a path that is not in required / optional. Possibly a typo or a leftover; the override is unused.
• MergeWarningKind::ProjectLocalForUndeclaredPath — a [secret."x"] block exists for a path that is not in required / optional. Same shape as the previous warning; metadata is registered but no caller depends on it.

Structs

MergeOutput

Output of merge_manifest — the resolved view plus advisory warnings.

MergeWarning

Advisory warning emitted by the merge.

ResolvedSecret

Resolved view of a single declared path — final metadata plus provenance.

Enums

MergeError

Fatal merge errors.

MergeWarningKind

Categories of advisory warnings — see the module-level doc for detailed descriptions.

OverrideField

Which behavioural field of a global entry was replaced by the project’s [overrides] block.

SecretOrigin

Where the resolved metadata for a path came from.

Functions

merge_manifest

Merge the per-project manifest with the global index per ADR-020 §4.