# RT3 Reverse-Engineering Handbook

This handbook is the project bootstrap for reverse-engineering and rewriting Railroad Tycoon 3.
It is written for future us first: enough structure to resume work quickly, without pretending the
project is already mature.

## Canonical Target

- Canonical executable: `rt3_wineprefix/drive_c/rt3/RT3.exe` (patch 1.06)
- Reference executable: `rt3_wineprefix/drive_c/rt3_105/RT3.exe` (patch 1.05)
- Canonical SHA-256: `01b0d2496cddefd80e7e8678930e00b13eb8607dd4960096f527564f02af36d4`
- Reference SHA-256: `9e96b0695cb722a700f99c8dce498d34da7235e562b1e275bcc1764f8c9b7eb1`

## Documents

- `setup-workstation.md`: toolchain baseline and local environment setup.
- `re-workflow.md`: how to analyze the binary, record findings, and export reusable artifacts.
- `function-map.md`: canonical schema and conventions for function-by-function mapping.
- `control-loop-atlas.md`: compatibility index for the split atlas, preserving legacy anchors.
- `control-loop-atlas/`: canonical section files for the atlas narrative.
- `runtime-rehost-plan.md`: bottom-up runtime replacement plan and milestone breakdown.

## Repo Conventions

- `docs/`: stable project guidance and durable design notes.
- `tools/py/`: committed Python helpers for analysis and validation.
- `artifacts/exports/`: committed derived outputs that can be regenerated.
- Local-only state stays untracked: `.venv/`, Ghidra projects, Rizin databases, crash dumps, and other
  bulky/generated working files.

## Current Baseline

The current technical milestone is a repeatable loop-mapping workflow for the 1.06 executable.
Before injection work or deep file-format work, we capture:

- executable hashes and PE metadata
- section layout, imports, and notable strings
- a starter subsystem inventory plus a control-loop atlas
- focused address and string context exports for branch-deepening passes
- a reusable CLI RE kit for branch dossiers where the atlas needs deeper grounding
- a stable curated function ledger in `artifacts/exports/rt3-1.06/function-map.csv`

Current coverage is broad enough to support future sessions without rediscovery, especially in:

- CRT startup and bootstrap handoff
- shell frame, layout, presentation, deferred-message, and frontend overlay flow
- Multiplayer.win UI, chat, session-event, and transport ownership
- map/scenario load and text-export paths
- shared support layers such as intrusive queues, vectors, hashed stores, and tracked heaps

README maintenance rule:

- Keep this section at subsystem level only.
- Do not mirror per-pass function additions here.
- Detailed mapping progress belongs in `artifacts/exports/rt3-1.06/function-map.csv` and the derived branch artifacts under `artifacts/exports/rt3-1.06/`.

Current local tool status:

- Ghidra is installed at `~/software/ghidra`
- `~/software/ghidra/ghidraRun` launches successfully in an interactive shell
- Rizin is installed and available on `PATH`
- `winedbg` works with `rt3_wineprefix`
- RT3 launches under `/opt/wine-stable/bin/wine` when started from `rt3_wineprefix/drive_c/rt3`

## Next Focus

The atlas milestone is broad enough that the next implementation focus has already shifted downward
into runtime rehosting. The current runtime baseline now includes deterministic stepping, periodic
trigger dispatch, normalized runtime effects, staged event-record mutation, fixture execution,
state-diff tooling, tracked save-slice documents for captured-runtime inputs, overlay import
documents that combine captured snapshots with save-derived state, and a packed-event persistence
bridge that now reaches per-record summaries and selective executable import.

The highest-value next passes are now:

- preserve the atlas and function map as the source of subsystem boundaries while continuing to
  avoid shell-first implementation bets
- keep using overlay imports as the context bridge when selectively executable packed rows still
  need runtime context that current save slices and raw save inspection do not yet persist
- treat broader real grouped-descriptor recovery as the active packed-event frontier now that the
  first company-scoped batch already parses, summarizes, and executes through the ordinary runtime
  path when overlay context resolves its symbolic company scope: descriptor `2` `Company Cash`,
  descriptor `13` `Deactivate Company`, and descriptor `16` `Company Track Pieces Buildable`
- descriptors `1` `Player Cash` and `14` `Deactivate Player` now join that executable real batch
  through the same ordinary runtime path, backed by the minimal player runtime and overlay-import
  context
- the first chairman-targeted real grouped rows now execute too through that same path when the
  hidden grouped target-subject lane resolves to grounded chairman scope ordinals `0..3`:
  `condition_true_chairman`, `selected_chairman`, `human_chairmen`, and `ai_chairmen`; wider
  chairman ordinals stay parity-only under `blocked_chairman_target_scope`
- chairman runtime ownership is broader now too: selected-chairman condition rows for chairman
  cash, holdings value, net worth, and purchasing power import through the same service path, and
  the first grounded company governance issue batch now executes too via book-value-per-share,
  investor-confidence, and management-attitude thresholds; wider chairman target ordinals remain
  frontier
- checked-in save-slice documents can now carry explicit company rosters and chairman profile
  tables too, so the current company-targeted and chairman-targeted descriptor/condition batches
  can execute from standalone save-slice fixtures without overlay snapshots when that context is
  present; raw `.gms` inspection/export now reconstructs those company/chairman collections
  directly from save-side tagged record families, while the fixed save-side `0x32c8` world block
  still provides selected company/chairman ids plus the grounded campaign-override, issue-`0x37`
  value/multiplier, and chairman-slot / role-gate analysis bytes; the current raw-save frontier is narrower now:
  company/chairman identity, active flags, links, chairman cash, chairman holdings, chairman
  purchasing power, company debt, company track-laying capacity, and collection counts are
  grounded, while broader company
  finance/governance scalar lanes plus controller-kind reconstruction still remain conservative
  defaults until their raw offsets are pinned more strongly; the offline analysis command
  `runtime inspect-save-company-chairman <save.gms>` now dumps those remaining raw record
  candidates directly from the rehosted parser, including fixed-world chairman slot / role-gate
  context, the grounded fixed-world issue-`0x37` pair, the fixed-dword world finance
  neighborhood rooted at `[world+0x0d]` with the saved calendar tuple and absolute counter, the separate six-float economic
  tuning band, derived holdings-at-share-price and cached purchasing-power totals,
  context, company dword candidate windows, and richer chairman qword cache views; the current
  rehosted company-side owner state now also includes a typed market/cache map carrying saved
  outstanding-shares, support/share-price/cache words, salary lanes, calendar words, connection
  latches, and the first grounded stat-band root windows at `[company+0x0cfb]`, `[company+0x0d7f]`,
  and `[company+0x1c47]` for each live company, so later finance/stat-family readers can attach to
  owned runtime data instead of one more guessed save offset; the first runtime-side `0x2329`
  stat-family reader seam is now also rehosted for slots `0x0d` and `0x1d`, and the saved
  stat-band windows themselves now carry 32 dwords per root; the matching world-side issue reader
  seam is now rehosted for the grounded `0x37` lane, and the adjacent raw issue-byte strip
  `0x37..0x3a` now also flows through save-slice/runtime restore state for later credit / prime
  / management readers; selected-company summaries now expose the
  unassigned share pool derived from outstanding shares minus chairman-held shares for later annual
  finance logic; that same owned company market state now also backs a bundled annual-finance
  reader seam for assigned shares, public float, and rounded cached share price; the fixed-world
  finance neighborhood is now widened to 17 dwords rooted at `[world+0x0d]` so later issue-family
  readers can target a broader owned restore-state window, and the saved absolute counter now
  flows through normal runtime restore state instead of staying on shell-context metadata; that
  same world owner surface now also carries the packed year word and partial-year progress lane
  behind annual-finance recent-history weighting; the same annual-finance state now also
  feeds a shared company market reader for stock-capital, salary, bonus, and the full two-word
  current/prior issue-calendar tuples, and now derives elapsed years since founding, last dividend,
  and last bankruptcy for later annual finance-policy rehosting; live bond-slot count now travels through that same owned annual-finance
  state for the stock-capital branch gate, and the grounded bond table now also contributes both
  the largest live bond principal and the chosen highest-coupon live bond principal into that same
  owner-state surface, plus the highest live coupon rate for the stock-capital approval ladder;
  the same fixed-world save block now also carries the raw stock, bond,
  bankruptcy, and dividend finance-policy bytes, and the first annual creditor-pressure branch now
  executes as a pure runtime reader over that owner state instead of remaining atlas-only; the
  later deep-distress bankruptcy fallback now runs on that same save-native cash and trailing-
  profit seam; the annual bond, stock-repurchase, and stock-capital issue branches now do too,
  and periodic boundary service now also commits the bond-issue branch through that owned
  stat-post and live-bond seam instead of leaving it as a reader-only finance lane; the rehosted
  company market reader now carries the first bundled annual net-profit surface too; the annual
  dividend-adjustment branch now does as well through the
  shared year-or-control-transfer reader and board-approved dividend ceiling helper; the same
  owner seam now also carries the fixed-world building-density
  growth setting plus the linked chairman personality byte, which is enough to run the annual
  stock-repurchase gate headlessly as another pure reader; periodic boundary service now also
  chooses one annual-finance action per active company and already commits the shellless
  creditor-pressure-bankruptcy, deep-distress-bankruptcy, dividend-adjustment, stock-repurchase,
  stock-issue, and annual bond-restructure branches against owned runtime state, with bankruptcy now following
  the grounded “halve live bond debt and stamp the year” path rather than a liquidation shortcut;
  the same live bond-slot owner
  surface now also carries save-native maturity years into annual bond policy summaries, derives the current live coupon burden
  directly from owned bond slots, and now also commits the shellless “repay matured live bonds,
  compact the table, then issue the exact staged count” path during periodic service; the same
  service surface now also carries the per-cycle retired-versus-issued principal totals that feed
  the later debt-news family plus the issued-share and repurchased-share counts behind the later
  equity-offering and buyback news tails; runtime summaries now also expose the grounded
  retired-versus-issued relation directly, and annual finance service now maps that same relation
  onto the exact debt headline selectors `2882..2886`
  while persisting the last emitted annual-finance news events as structured runtime-owned records
  carrying company id, selector label, action label, and the grounded debt/share payload totals
- shellless calendar advance now also drives that annual seam directly: `StepCount` and `AdvanceTo`
  invoke periodic-boundary service automatically on year rollover instead of requiring a second
  manual service pass to make the annual finance stack run
- that stepped world-time path now also refreshes the derived selected-year gap scalar owner lane
  `[world+0x4ca2]`, so later selected-year and periodic-boundary world work can build on runtime
  state instead of a frozen load-time scalar
- that same save-native world restore surface now also carries the grounded locomotive-policy bytes
  and cached available-locomotive rating from the fixed world block, so the `All
  Steam/Diesel/Electric Locos Avail.` descriptor strip now writes through owner state instead of
  living only as mirrored world flags
- the selected-year seam now follows the same rule: the checked-in `0x00433bd0` year ladder now
  drives a derived selected-year bucket scalar in runtime restore state, and the economic-tuning
  mirror `[world+0x0bde]` now rebuilds from tuning lane `0` instead of freezing one stale
  load-time word
- that same selected-year owner family now also rebuilds the direct bucket trio
  `[world+0x65/+0x69/+0x6d]`, the complement trio `[world+0x71/+0x75/+0x79]`, and the scaled
  companion trio `[world+0x7d/+0x81/+0x85]` from the bucket scalar instead of preserving stale
  save-time residue
- the same save-native company direct-record seam now also carries the full outer periodic-company
  side-latch trio rooted at `0x0d17/0x0d18/0x0d56`, including the preferred-locomotive
  engine-type chooser byte beside the city-connection and linked-transit finance gates
- that same seam now also resolves the base world route-preference byte at `[world+0x4c74]`, the
  effective electric-only override fed by `0x0d17`, and the matching `1.4x` versus `1.8x`
  route-quality multiplier as a normal runtime reader instead of a pure atlas note
- that same seam now also owns the first route-preference mutation path directly: beginning the
  electric-only periodic-company override rewrites the world route-preference byte to the
  effective company preference, ending it restores the base world byte, and runtime service state
  now carries both the active and last applied override
- save inspection now also separates the shared `0x5209/0x520a/0x520b` save family correctly: the
  smaller direct `0x1d5` collection is the live train family and now exposes a live-entry
  directory rooted at metadata dword `16`, while the actual region collection is the larger
  non-direct `Marker09` family; the tagged placed-structure header `0x36b1/0x36b2/0x36b3`
  remains grounded alongside them, so the remaining city-connection / linked-transit blocker is
  record-body reconstruction rather than missing save-side collection identity
- the project rule on the remaining closure work is now explicit too: when one runtime-facing field
  is still ambiguous, prefer rehosting the owning source state or real reader/setter family first
  instead of guessing another derived leaf field from neighboring raw offsets; the checked-in
  `docs/rehost-queue.md` file is the control surface for that work loop, and after each commit the
  next queue item should run unless the queue is empty, a real blocker remains that cannot be
  advanced by any further non-hook work without guessing, or approval is needed
- `rrt-runtime` now also exposes higher-layer probe commands for the current blocked frontier:
  `runtime inspect-periodic-company-service-trace <save.gms>`,
  `runtime inspect-region-service-trace <save.gms>`, and
  `runtime inspect-infrastructure-asset-trace <save.gms>`. These reports make the current
  shellless city-connection / linked-transit blockers explicit as missing owner seams rather than
  generic “still unresolved” residue.
- a checked-in `EventEffects` export now exists at
  `artifacts/exports/rt3-1.06/event-effects-table.json`, and a checked-in semantic closure layer
  now exists at `artifacts/exports/rt3-1.06/event-effects-semantic-catalog.json`
- recovered descriptor rows now land on explicit semantic frontier buckets such as
  `blocked_shell_owned_descriptor`, `blocked_evidence_blocked_descriptor`, and
  `blocked_variant_or_scope_blocked_descriptor` instead of generic unmapped-descriptor residue
- the first recovered governance descriptor tranche now executes through the generic
  company-governance scalar effect surface: descriptor `56` `Credit Rating` and descriptor `57`
  `Prime Rate`
- adjacent recovered finance/control-transfer descriptors such as `55` `Stock Prices` and `58`
  `Merger Premium` now land on explicit shell-owned descriptor parity instead of generic unmapped
  descriptor residue, with tracked fixtures now pinning finance, scenario-outcome, and
  control-transfer shell rows explicitly
- the recovered whole-game scalar economy/performance strip `59..104` now has a bounded runtime
  landing surface too: representative rows execute into `RuntimeState.world_scalar_overrides`
  through stable normalized keys such as `world.build_stations_cost` and
  `world.track_maintenance_cost`
- the runtime-variable strip `39..54` now executes too through bounded event-owned scalar maps on
  world/company/player/territory state, and the matching ordinary-condition strip now gates
  imported records through those same runtime-owned variable maps; these variables are still
  runtime-owned only in the current model and are not yet reconstructed from raw saves
- the grounded aggregate cargo-economics descriptors now execute too: descriptor `105`
  `All Cargo Prices` and descriptors `177..179` `All Cargo Production` / `All Factory Production`
  / `All Farm/Mine Production` land on bounded event-owned cargo override state, and the grounded
  named cargo-production strip `180..229` now lands on named cargo production overrides too
- the named cargo-price strip `106..176` now lands on named cargo price overrides too; the
  checked-in static selector reconstruction is now explicit because the broader 1.06 CargoTypes
  corpus has `51` names, the Cargo106 `cargoSkin` corpus has `70`, and the rehosted offline
  selector builder now closes the 71-row price strip as `cargoSkin` plus the core `Rock`
  carry-over; a new
  checked-in offline cargo-source report at
  `artifacts/exports/rt3-1.06/economy-cargo-sources.json` now parses both `CargoTypes` and the
  `Cargo106.PK4` `cargoSkin` descriptors through rehosted code, normalizes localized
  `~####Name` tokens into visible names, builds a merged live cargo registry, and now derives
  exact named cargo-production and named cargo-price selectors from the checked-in bindings;
  dedicated CLI inspector commands now expose both grounded selectors directly, while the same
  report still shows the nine excluded CargoTypes-only industrial names that sit outside the
  71-row price strip
- the add-building strip `503..519` is now explicitly classified as recovered shell-owned parity,
  with tracked fixture coverage, instead of generic unresolved descriptor residue
- widen real packed-event executable coverage descriptor by descriptor after identity, target mask,
  and normalized effect semantics are all grounded, not just after row framing is parsed
- the first grounded condition-side unlock now exists for negative-sentinel `raw_condition_id = -1`
  company scopes, and the first ordinary nonnegative condition batch now executes too: numeric
  thresholds for company finance, company track, aggregate territory track, and company-territory
  track
- exact named-territory binding now executes too, while named-territory no-match cases remain the
  explicit binding blocker frontier
- real descriptors `8` `Economic Status`, `9` `Confiscate All`, and `15` `Retire Train` now join
  the executable batch through the same ordinary runtime path, backed by the opaque economic-status
  lane and the minimal event-owned train roster
- descriptor `3` `Territory - Allow All` now executes as company-to-territory access rights through
  the same ordinary runtime path; shell purchase-flow parity remains out of scope, and mixed
  supported/unsupported real rows still stay parity-only
- whole-game ordinary-condition execution now exists too: special-condition thresholds,
  candidate-availability thresholds, and economic-status-code thresholds now gate imported runtime
  records, and the packed-event frontier now reports explicit unmapped world-condition and
  world-descriptor buckets
- that whole-game condition batch is now metadata-driven too: special-condition label ids,
  economic-status, and the generic `%1 Avail.` candidate-availability template plus candidate-name
  side strings all decode through checked-in world-condition metadata instead of fixture-only ids
- the first real whole-game grouped-descriptor batch is now metadata-driven too: checked-in
  descriptor metadata covers special-condition and candidate-availability setters, and descriptor
  `110` `Disable Stock Buying and Selling` now executes too through the checked-in keyed runtime
  flag `world.disable_stock_buying_and_selling`
- that world-toggle path now covers a broader recovered boolean scenario-rule band too:
  descriptors `111..138` now decode through checked-in metadata into either keyed `world_flags`
  or the bounded `world_restore.limited_track_building_amount` scalar for finance/trading,
  construction, and governance restrictions
- the late recovered world-toggle band now executes too where current evidence is equally strong:
  `Use Bio-Accelerator Cars`, `Disable Cargo Economy`, `Disable Train Crashes`,
  `Disable Train Crashes AND Breakdowns`, and `AI Ignore Territories At Startup`
- whole-game ordinary-condition coverage is broader now too: checked-in world-flag condition ids
  can lower into `world_flag_equals` gates for boolean equality/inequality forms, so real packed
  rows can gate whole-game effects on existing `world_flags`
- the tracked parity save-slice now keeps its remaining non-imported residue as structured
  `real_packed_v1` parity records, with the first captured leftover now pinned to the unresolved
  upper locomotives-page availability tail and moved onto explicit descriptor parity
- the next recovered locomotives-page descriptor batch is partially executable too:
  descriptors `454..456` (`All Steam/Diesel/Electric Locos Avail.`) now lower through checked-in
  metadata into keyed `world_flags`, while the wider locomotive availability/cost scalar bands now
  split cleanly between the grounded lower executable prefix and the explicit unresolved tails
- raw `.smp` inspection/export now reconstructs the persisted save-side named locomotive table and
  derives a minimal locomotive catalog from its row order, so save-slice documents can carry both
  `RuntimeState.named_locomotive_availability` and the catalog context needed for descriptor
  lowering
- recovered scalar locomotive availability and locomotive-cost descriptors now import through that
  save-native or embedded `RuntimeState.locomotive_catalog` context into the ordinary
  `named_locomotive_availability` and `named_locomotive_cost` runtime maps
- the grounded executable lower locomotive prefix now extends through save-backed locomotive id
  `61` (`Zephyr`); the unresolved lower tail and upper locomotive bands stay on explicit parity
- cargo-production `230..240` and territory-access-cost `453` now execute too through minimal
  world-side scalar landing surfaces: slot-indexed `cargo_production_overrides` and
  `world_restore.territory_access_cost`
- recipe-book probing now derives a save-native `cargo_catalog` too, so save-slice documents carry
  stable cargo slot labels and token-stem evidence into runtime state without requiring a separate
  cargo simulation layer
- world-scalar ordinary-condition coverage now matches those runtime surfaces too: checked-in
  metadata lowers named locomotive availability, named locomotive cost, named cargo-production
  slot thresholds, aggregate cargo production, factory/farm-mine/other cargo production,
  limited-track-building-amount, and territory-access-cost rows into explicit runtime condition
  gates
- cargo slot classification is now checked in and save-native too, so the remaining cargo frontier
  is broader descriptor/condition breadth rather than classification or save/import plumbing
- the company/chairman frontier has moved too: checked-in save-slice documents can now carry that
  context natively, so the next work on that axis is broader recovery and eventual raw save
  reconstruction rather than overlay-only ownership
- keep in mind that the current local `.gms` corpus still exports with no packed event collection,
  so real descriptor mapping needs to stay plumbing-first until better captures exist
- use `rrt-hook` primarily as optional capture or integration tooling, not as the first execution
  environment
- keep `docs/runtime-rehost-plan.md` current as the runtime baseline and next implementation slice
  change

Regenerate the initial exports with:

```bash
python3 tools/py/collect_pe_artifacts.py \
  rt3_wineprefix/drive_c/rt3/RT3.exe \
  artifacts/exports/rt3-1.06
```

Regenerate the startup-focused Ghidra exports with:

```bash
python3 tools/py/export_startup_map.py \
  rt3_wineprefix/drive_c/rt3/RT3.exe \
  artifacts/exports/rt3-1.06
```

Regenerate the checked-in `EventEffects` table export with:

```bash
python3 tools/py/extract_event_effects.py \
  rt3_wineprefix/drive_c/rt3/RT3.exe \
  rt3_wineprefix/drive_c/rt3/Data/Language/RT3.lng \
  artifacts/exports/rt3-1.06/event-effects-table.json
```

Regenerate the checked-in `EventEffects` semantic catalog with:

```bash
python3 tools/py/build_event_effect_semantic_catalog.py \
  artifacts/exports/rt3-1.06/event-effects-table.json \
  artifacts/exports/rt3-1.06/event-effects-semantic-catalog.json
```

That default export now walks two roots:

- `entry:0x005a313b`
- `bootstrap:0x00484440`

For a focused branch-deepening pass, regenerate the analysis context exports with:

```bash
python3 tools/py/export_analysis_context.py \
  rt3_wineprefix/drive_c/rt3/RT3.exe \
  artifacts/exports/rt3-1.06 \
  --addr 0x00444dd0 \
  --addr 0x00508730 \
  --addr 0x00508880 \
  --string gpdLabelDB \
  --string gpdCityDB \
  --string 2DLabel.imb \
  --string 2DCity.imb \
  --string "Geographic Labels"
```

For the pending-template dispatch-store branch, regenerate the new branch dossier with:

```bash
python3 tools/py/rt3_rekit.py \
  pending-template-store \
  rt3_wineprefix/drive_c/rt3/RT3.exe \
  artifacts/exports/rt3-1.06
```

That dossier is now a targeted follow-up tool, not the default first pass.
