Summary

Add behavioral coverage for the embedded Zsh completion script using a real Zsh process. The tests validate representative top-level candidates and the exact plugin subcommand candidates while stubbing only the interactive completion primitives.

Related: #2042

Testing

• go test -race ./internal/completions -count=1
• focused completion test repeated 20 times
• go test ./internal/... -count=1
• repository-wide compilation with go test ./... -run ^TestZshCompletionCandidates$ -count=1
• Go vet, gofumpt, revive, and staticcheck for the completions package
• go build ./...
• git diff --check

The test skips on hosts without Zsh. The unrestricted repository test suite was not run locally because its legacy integration tests require bats, which is unavailable in this environment; the macOS CI job provides Zsh execution.

Assistance

AI assistance was used during implementation and test analysis.