2.1 KiB
Agent Note: Root marker metadata failures
Status: implemented
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Problem
Project-root discovery probes each configured marker while walking upward from the session working directory. Treating every resolve or stat failure as a missing marker lets a permission, I/O, or provider failure continue into an ancestor project and load unrelated workspace instructions. The discovery result must distinguish confirmed absence from unavailable metadata.
Decision
Root-marker discovery continues upward only when host stat reports ENOENT or ENOTDIR, or when a filesystem provider returns no stat information or reports FS_NOT_FOUND from resolution or stat. It rethrows every other marker error unchanged after checking cancellation. Instruction-file candidates keep their separate availability policy: resolution, stat, and read failures skip only that candidate because files can race with discovery without changing project identity.
Alternatives considered
Treat every marker failure as absence and continue upward. Rejected because an inaccessible child directory could inherit instructions from an unrelated ancestor project while discovery reports success.
Stop at the first unavailable marker and use the session working directory as the root. Rejected because it converts an unknown project root into a different project identity and can silently omit valid broader instructions.
Consequences
Project-root discovery favors correct project identity over availability: one non-missing metadata failure anywhere in the ancestor walk rejects baseline loading with the original error. Instruction-file candidate failures retain their existing skip behavior. A failed baseline creates no workspace-context Session event, so the keyless recorded-session harness has no durable output for this path.
Verification
Focused unit tests cover confirmed provider absence and unavailable host and provider marker metadata. The unavailable cases also prove that ancestor instructions do not enter derived model history.