Previously, kubectx would error with "multiple files in KUBECONFIG are
currently not supported" when KUBECONFIG contained colon-separated paths.
This is a common setup where users maintain separate kubeconfig files for
different clusters/environments.
This change evolves the internal Kubeconfig struct from holding a single
file to a slice of file entries, matching kubectl's merge semantics:
- Reading current-context: first file with a non-empty value wins
- Writing current-context: always written to the first file
- Listing contexts: merged from all files, first occurrence wins for
duplicate names
- Modifying a context (delete/rename/set-namespace): written to the
file that owns that context
- Missing files in the KUBECONFIG list are silently skipped (matching
kubectl behavior), but permission errors are propagated
The Loader interface already returned []ReadWriteResetCloser, so all
public method signatures remain unchanged — zero modifications needed
in cmd/kubectx/ or cmd/kubens/ callers.
Fixes#485Fixes#211
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
