Local train routing instead of global pathfinding

[scamiv]

This is not yet a pr but a idea to tackle multiple train related issues. Feedback very welcome! Code needs cleanup!

Description:

Before: Trains followed fixed, pre-calculated paths between stations using a pathfinding algorithm
After: After: Trains now use a local cost based routing system.

Local Greedy Routing (Smart decision-making at each station)

At each station, trains evaluate neighboring stations based on multiple factors:
Profit potential: How much gold they can earn based on diplomatic relationships
Traffic congestion: Avoids overcrowded stations
Travel distance: Considers physical distance and travel time
Recent history: Avoids recently visited stations to prevent loops
Some randomness: chance of making a non-optimal choice for exploration

Key Benefits

Organic route discovery: Routes improve as trains explore the network
Congestion avoidance: Trains naturally spread out to less busy areas
Adaptive behavior: System responds to changing network conditions
Loop prevention: Memory of recent visits discourages trains from getting stuck

Currenlty disabled:
BATMAN like broadcast.
Stations broadcast routing information to neighbors like the BATMAN wireless mesh protocol Builds a distributed routing table that learns about the entire network over time Handles network topology changes automatically
Uses lazy cleanup to manage memory efficiently

Settings need to be tweaked

Performance impact is not yet measured, but could be positive.

Describe the PR.

Please complete the following:

• I have added screenshots for all UI updates
• I process any text displayed to the user through translateText() and I've added it to the en.json file
• I have added relevant tests to the test directory
• I confirm I have thoroughly tested these changes and take full responsibility for any bugs introduced

Please put your Discord username so you can be contacted if a bug or regression is found:

DISCORD_USERNAME

[coderabbitai]

Walkthrough

Refactors train traversal to local greedy routing with journey tracking and hop limits; adds station-originated routing broadcasts and traffic metrics; injects station tick calls; extends Game API and GameImpl with train arrival/hop-limit recording and runtime stats; invokes station cleanup on removal.

Changes

Cohort / File(s)	Change Summary
Train execution src/core/execution/TrainExecution.ts	Replaces path-array navigation with step-based greedy routing: currentStation, recentStations, hop counters, arrival/departure handling, getNextStep() and shareJourneyInfo(); adds arrival processing, hop-limit removal, and car positioning adjustments.
Station execution tick src/core/execution/TrainStationExecution.ts	Calls TrainStation.tick() each station-exec tick (before spawn) so stations broadcast/age routing and update edge/traffic state.
Game API & stats src/core/game/Game.ts, src/core/game/GameImpl.ts	Adds recordTrainArrival(steps) and recordTrainRemovedDueToHopLimit(steps) to Game; GameImpl tracks arrivals, completed/active steps, hop-limit removals, exposes getActiveTrainCount(), getAverageCompletedTrainSteps(), getAverageActiveTrainSteps(), printTrainStats(), and prints periodic summaries.
Station routing & types src/core/game/TrainStation.ts	Introduces BATMAN-like routing and types (RoutingEntry, RoutingEntryFull, EdgeMetrics, StationTraffic), routing table with sequence numbers, originator broadcasts (broadcastOriginatorMessage, receiveOriginatorMessage, tick()), edge/traffic metrics, greedy neighbor selection (chooseNextStation, chooseGreedyNeighbor), journey-driven reverse-route updates (processJourneyInformation, updateReverseRouteFromJourney), and removal handlers.
Rail network lifecycle src/core/game/RailNetworkImpl.ts	Calls station.onStationRemoved() after disconnecting a station to allow station-level cleanup before deregistration.

Sequence Diagram(s)

sequenceDiagram
    participant GameLoop as Game.executeNextTick
    participant GameImpl as GameImpl
    participant StationExec as TrainStationExecution
    participant Station as TrainStation
    participant TrainExec as TrainExecution

    GameLoop->>+GameImpl: executeNextTick()
    GameImpl->>+StationExec: tick all stations
    StationExec->>+Station: tick()
    Note right of Station `#E8F0FF`: Broadcast/age routes\nupdate edge metrics & traffic
    Station-->>-StationExec: done
    StationExec->>GameImpl: spawn trains (if any)

    GameImpl->>+TrainExec: tick trains
    alt train moving
        TrainExec->>Station: shareJourneyInfo() (optional)
        TrainExec->>Station: chooseNextStation(destination,recent)
        Station-->>TrainExec: nextHop / null
        TrainExec->>TrainExec: processArrival/update journey
        TrainExec->>GameImpl: recordTrainArrival(steps)
    else hop limit exceeded
        TrainExec->>GameImpl: recordTrainRemovedDueToHopLimit(steps)
    end

    GameImpl->>GameImpl: accumulate per-tick stats
    alt every 60 ticks
        GameImpl->>GameImpl: printTrainStats()
    end

Loading

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

• Review focus:
  • src/core/game/TrainStation.ts — routing protocol correctness, sequence/aging, and edge/traffic scoring.
  • src/core/execution/TrainExecution.ts — journey state transitions, hop-limit logic, and shareJourneyInfo() integration.
  • src/core/game/GameImpl.ts — stat aggregation, timing, and public API behavior.
  • src/core/game/RailNetworkImpl.ts — removal ordering and side-effects.

Possibly related PRs

• Add trains #1159 — overlaps train/station subsystem changes; likely touching routing and lifecycle code.
• Automatic train stations #1353 — modifies TrainExecution/TrainStation and may conflict or overlap with routing redesign.
• Factory spawns trains #1408 — related changes to TrainStationExecution.tick and spawn flow; relevant to inserted station tick call.

Suggested labels

Feature - Simulation

Suggested reviewers

• evanpelle
• scottanderson

Poem

🚂 Trains learn paths by whisper and hop,
Stations hum routes that never stop,
Counters tick steps, memories share,
Greedy choices guide them there,
Rails and stats in tidy crop.

Pre-merge checks

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly describes the main architectural change: replacing global pathfinding with local routing, which aligns with all major modifications across TrainExecution, TrainStation, and Game components.
Description check	✅ Passed	The description relates to the changeset by explaining the local greedy routing system, benefits, and current state; however, it's incomplete with placeholder text, unchecked checklist items, and 'code needs cleanup' warning suggests work-in-progress status.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[ryanbarlow97]

Personally, I'd say close this and work off the new branch you made, once it's ready, make a new PR using that branch

[evanpelle]

I like the idea of local pathfinding. this approach seems a bit overly complex to me. is there a way to simplify this down to something like 100 lines?

[scamiv]

Maybe discuss the changes here https://discord.com/channels/1359946986937258015/1441027562967928862 ?