Current Status (Research Findings)

• Group data structure: src/group.h Group (name/owner/vehicle_type/flags/livery/statistics/parent/number), GroupID, DEFAULT_GROUP;
• Existing commands (src/group_cmd.h / group_cmd.cpp):
  • CmdCreateGroup, CmdDeleteGroup, CmdAlterGroup (rename/set parent group)
  • CmdAddVehicleGroup (single vehicle into group)
  • CmdAddSharedVehicleGroup (adds vehicles sharing orders with a given vehicle to an existing group)
  • CmdCreateGroupFromList (create group from a vehicle list, supports VL_SHARED_ORDERS list type; auto-naming)
• Auto-naming helper: GenerateAutoNameForVehicleGroup() (group_cmd.cpp:899, by route start/end town STR_VEHICLE_AUTO_GROUP_ROUTE / _LOCAL_ROUTE) — jgrpp already has the "name by route" infrastructure;
• Command registration mechanism: command_type.h enum class Commands + DEF_CMD_TUPLE_NT (macro that simultaneously declares the handler and registers CommandTraits);
• Vehicle↔Group: vehicle_base.h Vehicle::group_id; shared order chain FirstShared()/NextShared(); OrderList *orders.

Conclusion: Missing a single command that "iterates all company vehicles, auto-creates groups by shared orders, and assigns vehicles to them."

This Feature Implementation

New Command Commands::AutoGroupSharedOrders (CmdAutoGroupSharedOrders)

Flow (src/group_cmd.cpp):

1. Iterate all primary vehicles of the specified type for the company (Vehicle::IterateTypeFrontOnly(type)), skip vehicles not owned by this company, without orders, or already in a custom group;
2. Count each shared order chain; when ≥2 vehicles share the same order list:
   • Use GenerateAutoNameForVehicleGroup(v) to generate a group name (e.g., "Town A ↔ Town B");
   • Construct VehicleListIdentifier(VL_SHARED_ORDERS, ...), nest a call to Command<Commands::CreateGroupFromList>::Do(flags, ...) to create the group and move all shared vehicles into it;
   • After completion, vehicles in that group have a group_id different from the default group, so the loop automatically skips them (only one group per order list);
3. GroupChangeDeferredUpdateScope defers group statistics updates uniformly.

Three Entry Points

Entry Point	Location	Description
Group window button	src/group_gui.cpp new WID_GL_AUTOGROUP_SHARED (toolbar near LIVERY), OnClick sends command	Reuses SPR_GROUP_CREATE_TRAIN + vtype sprite
Console command	src/console_cmds.cpp autogroup [train|road|ship|aircraft] (no argument = execute for all four types)	IConsole::CmdRegister
Script/Other	Any code can call Command<Commands::AutoGroupSharedOrders>::Post(...)	Command goes through network sync, safe for multiplayer servers

Involved Files

• src/command_type.h: Commands enum adds AutoGroupSharedOrders (Note: inserting in the middle shifts subsequent command IDs, causing inconsistency between old and new version multiplayer — this is normal within a fork)
• src/group_cmd.h / group_cmd.cpp: command declaration and implementation
• src/widgets/group_widget.h: new widget ID
• src/group_gui.cpp: toolbar button (NWidget + OnPaint sprite + OnClick)
• src/console_cmds.cpp: console command
• src/lang/english.txt: STR_GROUP_AUTOGROUP_SHARED_TOOLTIP

Verification Points

1. Two or more vehicles sharing the same order list → clicking the button / autogroup creates a "route name" group with all vehicles assigned;
2. Already grouped vehicles are not moved again; different order lists each form their own group;
3. Group vehicle statistics (count/profit) are correctly refreshed (depends on GroupChangeDeferredUpdateScope).