Contributing: hybrid mirror (in-cli ↔ rust-driver)

The in crate (in-cli) vendors hybrid pipeline sources that must stay aligned with compiler/rust-driver. The published inauguration package is built from in-cli; drift between these trees breaks publish parity with the workspace compiler (different behavior, duplicated fixes, or CI that passes in one layout but not the other).

Treat edits to either side as edits to both until extraction or automation lands (see native Swift master plan — Phase 0).

Mirrored paths

`in-cli` source	`compiler/rust-driver` crate (canonical `lib.rs`)
`in-cli/src/hybrid_core.rs`	`compiler/rust-driver/crates/core/src/lib.rs`
`in-cli/src/hybrid_scheduler.rs`	`compiler/rust-driver/crates/scheduler/src/lib.rs`
`in-cli/src/hybrid_sil.rs`	`compiler/rust-driver/crates/sil/src/lib.rs`
`in-cli/src/hybrid_pipeline.rs`	`compiler/rust-driver/crates/pipeline/src/lib.rs`

Rust module boundaries inside each crate may split across src/lib.rs and submodules in the future; compare directory trees and entry APIs, not only single files.

Manual sync checklist

Before opening a PR that touches hybrid logic on either side:

Identify the canonical side for your change (prefer fixing in compiler/rust-driver first, then mirror into in-cli, unless the change is CLI-specific glue).
Diff the mirrored pairs after copying or editing. From the repo root, each workspace crate is a single lib.rs inlined into the matching hybrid_*.rs (expect use path differences: hybrid_* uses crate::hybrid_*, crates use hybrid_* / workspace deps):
```
diff -u compiler/rust-driver/crates/core/src/lib.rs in-cli/src/hybrid_core.rs
diff -u compiler/rust-driver/crates/scheduler/src/lib.rs in-cli/src/hybrid_scheduler.rs
diff -u compiler/rust-driver/crates/sil/src/lib.rs in-cli/src/hybrid_sil.rs
diff -u compiler/rust-driver/crates/pipeline/src/lib.rs in-cli/src/hybrid_pipeline.rs
```
If a crate later splits into submodules, diff the touched subtree against the corresponding section of the vendored file.

Run tests on both workspaces:

cd compiler/rust-driver && cargo test --all
cd in-cli && cargo test

Confirm in test still passes from the repo root (project gate).

If automated mirroring is added later, keep this checklist as the human fallback when scripts fail or paths diverge.

Why drift matters

crates.io / release binaries ship in-cli sources; rust-driver is the in-tree compiler workspace. Unmirrored fixes can ship to users without landing in the driver (or vice versa).
Reviewers may only glance at one tree; explicit diff discipline reduces silent skew.

For roadmap context and Phase 0 exit criteria, see native-swift-master-plan.md.