Rust Cargo workspace smoke, evidence, and closeout

[jununfly]

This was generated by AI during triage.

What to build

Produce deterministic Plan 4 validation evidence for Cargo workspace/package taxonomy. Validate the synthetic workspace fixture, run mini-redis smoke, optionally add one reasonably sized real GitHub Rust workspace repository only if the fixture and mini-redis leave an important blind spot, and close out the roadmap node with an explicit no-cross-package-edge statement.

Plan: docs/plans/2026-06-27-rust-language-indexing-plan-4-cargo-workspace-package-frontier.md

Roadmap node: 1-4-4-4

Acceptance criteria

• Synthetic workspace fixture validates package/workspace/member/root/local-path taxonomy deterministically.
• mini-redis indexes successfully with rust-hybrid.
• Evidence records file/node/edge counts, Cargo/workspace taxonomy, deferred signals, and RSS or unavailable reason.
• Optional real GitHub Rust workspace validation is included only if the local fixture and mini-redis leave an important blind spot.
• Evidence explicitly states that Plan 4 writes no cross-package graph edges.
• Roadmap node 1-4-4 is updated when the slice completes.

Blocked by

• Rust Cargo.toml package and workspace metadata taxonomy #578
• Rust file package and crate-root ownership diagnostics #579
• Rust workspace-local crate candidate taxonomy #580

[jununfly]

This was generated by AI during triage.

Closing with Plan 4 evidence recorded. Synthetic workspace coverage validates workspace members/local path dependencies; mini-redis Rust core smoke passed with RSS evidence; CLI rust-hybrid smoke was blocked by the local Node.js 26 gate and recorded as an environment gate rather than a Plan 4 taxonomy failure.

Evidence: docs/benchmarks/2026-06-27-rust-language-indexing-plan-4-evidence.md

Verification: cargo test --package zcodegraph-core, npm run build.