rrt/README.md

Analysis and reimplementation of Railroad Tycoon 3


The old executable is at ./rt3_wineprefix/drive_c/rt3/RT3.exe

Our first task is to understand the executable's high-level control loops and subsystem boundaries well
enough to choose good rewrite targets. As we go, we document evidence, keep a curated function map,
and stand up Rust tooling that can validate artifacts and later host replacement code.

The long-term direction is still a DLL we can inject into the original executable, patching in
individual functions as we build them out. The active implementation milestone is now a headless
runtime rehost layer that can execute deterministic world work, compare normalized state, and grow
subsystem breadth without depending on the shell or presentation path. The current packed-event
frontier is real grouped-descriptor semantic mapping on top of the existing save-slice, snapshot,
overlay-import, compact-control, and symbolic company-target workflows. The runtime already carries
selected-company and controller-role context through overlay imports so synthetic packed records can
execute `selected_company`, `human_companies`, and `ai_companies` scopes without a parallel packed
executor, while condition-relative company scopes remain explicitly blocked. The PE32 hook remains
useful as capture and integration tooling, but it is no longer the main execution milestone.

## Project Docs

Bootstrap design and workflow documents live in `docs/`.

- `docs/README.md`: handbook index and target hashes
- `docs/control-loop-atlas.md`: compatibility index for the split atlas
- `docs/control-loop-atlas/`: canonical atlas section files
- `docs/setup-workstation.md`: toolchain baseline and local setup
- `docs/re-workflow.md`: repeatable reverse-engineering workflow
- `docs/function-map.md`: canonical function-map schema and conventions

The first committed exports for the canonical 1.06 executable live in `artifacts/exports/rt3-1.06/`.

## Rust Workspace

The Rust workspace is split into focused crates:

- `rrt-model`: shared types for addresses, function-map rows, and control-loop concepts
- `rrt-runtime`: headless runtime state, stepping, normalized event service, and persistence-facing
  runtime types
- `rrt-fixtures`: fixture schemas, loading, normalization, and diff helpers for rehost validation
- `rrt-cli`: validation, runtime fixture execution, state-diff tools, and repo-health checks
- `rrt-hook`: minimal Windows DLL scaffold for low-risk in-process loading, capture, and later
  integration experiments under Wine

For the current headless runtime smoke path, use `cargo run -p rrt-cli -- runtime summarize-fixture
fixtures/runtime/minimal-world-step-smoke.json` or one of the broader runtime fixtures under
`fixtures/runtime/`.

For the current hook smoke test, run `tools/run_hook_smoke_test.sh`. It builds the PE32 proxy,
copies it into the local RT3 install, launches the game briefly under Wine with
`WINEDLLOVERRIDES=dinput8=n,b`, and expects `rrt_hook_attach.log` to appear.