Add roads and bridges

[anton-makarevich]

A single road/bridge tool. Automatically adds road on top on not-water textures and bridge if there is water.
There should be a way raise/lower bridge level and also adjust its constructor factor via the hexinfo popup. if to raise road level it automatically becomes a bridge and wise versa if to lower bridge over non-water terrain to 0 height it becomes a road

[anton-makarevich]

@coderabbitai plan

[coderabbitai]

Coding Plan

Summary

• Treat road and bridge as two states of the same construction concept — road at ground level, bridge when elevated or over water — sourced from the Sanet.MakaMek.Map package.
• Add a single RoadBridge toolbar tool whose paint handler chooses bridge over water and road otherwise, applied as an overlay that preserves underlying terrain.
• Extend the existing HexInfo popup and HexViewModel (mirroring the water-depth pattern) with bridge-level and construction-factor controls, plus automatic road↔bridge conversion as the level crosses zero over non-water terrain.
• Add tests following established conventions (real Hex/BattleMap, NSubstitute services, HexUpdated assertions).

Design Choices

Design Choice 1: Does `Sanet.MakaMek.Map` already expose Road/Bridge terrain types and a construction-factor property, or is a package upgrade required?

Options Considered:

1. The current pinned package version (0.60.10-preview) already ships RoadTerrain, BridgeTerrain, MakaMekTerrains.Road/Bridge, and a construction-factor/height API — only MapEditor-side wiring is needed.
2. The types do not yet exist and the Sanet.MakaMek.Map (and sibling Sanet.MakaMek.*) packages must be upgraded to a version that provides them before wiring.

Chosen Option: 1

Rationale: Option 1 as the primary path (verify the pinned version exposes the types and wire against them); fall back to Option 2 (bump all Sanet.MakaMek.* package versions in the .csproj files to the earliest version providing these types) if verification shows the types are missing. Rationale: minimizes churn and keeps all editor-domain types sourced from the package as the codebase intends. Road/Bridge/ConstructionFactor concepts do not appear anywhere in this repo, and the package source cannot be inspected in the sandbox. The editor cannot define domain terrain classes itself; they must come from the package.

💡 User Tips

Regenerate the plan with different choices with @coderabbitai <feedback>.

Implementation Steps

Phase 1: Domain Readiness and Terrain Registration

Establish the road/bridge terrain types as first-class, paint-registered terrains in the editor so the model can carry them, the toolbar can surface them, and the external HexControl can render them. This phase is about making the domain concept available to the rest of the editor.

Task 1: Confirm/enable Road and Bridge domain terrain types

Verify the terrain classes and enum members the feature depends on exist in the referenced package; upgrade if they do not.

• Verify that Sanet.MakaMek.Map (as referenced in src/MakaMek.MapEditor/MakaMek.MapEditor.csproj) exposes RoadTerrain, BridgeTerrain (or an equivalent single terrain carrying a level/height), corresponding MakaMekTerrains enum members, and a construction-factor property on the bridge terrain.
• If any are missing, bump the Sanet.MakaMek.* package versions consistently across src/MakaMek.MapEditor/MakaMek.MapEditor.csproj and src/MakaMek.MapEditor.Browser/MakaMek.MapEditor.Browser.csproj to a version that provides them.
• Confirm the semantic model: a road is the ground-level construction; a bridge is the elevated construction carrying a level and a construction factor. This mapping drives the conversion logic in later phases.

Task 2: Register road/bridge terrains and add the tool icon

Wire the new terrain(s) into the editor's terrain awareness and provide a toolbar icon.

• In src/MakaMek.MapEditor/ViewModels/EditMapViewModel.cs, extend the hard-coded KnownTerrains/terrain-awareness so the editor recognizes road and bridge terrains for rendering and info display (note: these will be applied via a dedicated tool rather than the generic terrain painter, so they should not necessarily appear as ordinary paint-terrain entries — see Phase 2).
• Add a combined tool icon asset under src/MakaMek.MapEditor/Assets/tools/ (e.g. roadbridge.png); the existing Assets/terrain/road.png may be reused/adapted, but a bridge visual asset does not yet exist and must be added if the toolbar/info UI needs one.
• Add localization keys (e.g. EditMap_RoadBridge, EditMap_BridgeLevel, EditMap_ConstructionFactor, EditMap_RaiseBridge, EditMap_LowerBridge, EditMap_IncreaseConstructionFactor, EditMap_DecreaseConstructionFactor) in the localization source used by MakaMekMapEditorFakeLocalizationService/ILocalizationService.

🤖 Prompt for AI agents

Goal: make the road/bridge domain concept available to the editor by
confirming/upgrading the referenced package and registering terrain awareness
plus supporting assets/localization.

- Verify `Sanet.MakaMek.Map` (referenced in
`src/MakaMek.MapEditor/MakaMek.MapEditor.csproj`) exposes `RoadTerrain`,
`BridgeTerrain` (or equivalent terrain carrying a level/height), the
corresponding `MakaMekTerrains` enum members, and a construction-factor property
on the bridge terrain.
- If any of these are missing, bump the `Sanet.MakaMek.*` package versions
consistently across `src/MakaMek.MapEditor/MakaMek.MapEditor.csproj` and
`src/MakaMek.MapEditor.Browser/MakaMek.MapEditor.Browser.csproj` to a version
that provides them.
- Confirm the semantic model: road = ground-level construction; bridge =
elevated construction with a level and construction factor. This mapping drives
later conversion logic.
- In `src/MakaMek.MapEditor/ViewModels/EditMapViewModel.cs`, extend the
hard-coded `KnownTerrains`/terrain-awareness so the editor recognizes road and
bridge terrains for rendering and info display. Note these will be applied via a
dedicated tool rather than the generic terrain painter, so they should not
necessarily appear as ordinary paint-terrain entries (handled in Phase 2).
- Add a combined tool icon asset under `src/MakaMek.MapEditor/Assets/tools/`
(e.g. `roadbridge.png`); the existing `Assets/terrain/road.png` may be
reused/adapted, but add a bridge visual asset if the toolbar/info UI needs one.
- Add localization keys (e.g. `EditMap_RoadBridge`, `EditMap_BridgeLevel`,
`EditMap_ConstructionFactor`, `EditMap_RaiseBridge`, `EditMap_LowerBridge`,
`EditMap_IncreaseConstructionFactor`, `EditMap_DecreaseConstructionFactor`) in
the localization source used by
`MakaMekMapEditorFakeLocalizationService`/`ILocalizationService`.

Phase 2: Combined Road/Bridge Tool

Introduce a single toolbar tool that, on hex click, decides between road and bridge based on whether the hex already contains water, and applies the appropriate terrain non-destructively (as an overlay on top of existing terrain rather than replacing it).

Task 1: Add the RoadBridge tool type and toolbar entry

Expose the combined tool in the toolbar following the existing non-terrain-payload tool pattern.

• Add a RoadBridge value to src/MakaMek.MapEditor/Models/ToolType.cs.
• In EditMapViewModel.LoadTerrains(), add an AvailableTools.Add(new ToolItem(...ToolType.RoadBridge..., imagePath: roadbridge icon)) entry alongside the existing RaiseLevel/water-depth tools (these carry no Terrain payload; the terrain choice is made in the paint handler).
• No change to the SelectedTool setter is required beyond it copying ToolType.RoadBridge into ActiveEditMode, since the tool carries no Terrain payload.

Task 2: Implement road-vs-bridge paint logic

Apply the correct construction terrain when the tool is active and a hex is clicked.

• Add a case ToolType.RoadBridge: branch in EditMapViewModel.HandleHexSelection.
• Decision logic: if the hex has water terrain (HasTerrain(Water)), add a bridge terrain (default level and default construction factor); otherwise add a road terrain. Add the construction terrain on top of existing terrains (use AddTerrain, not ReplaceTerrains) so the underlying terrain is preserved; guard against duplicating an already-present road/bridge.
• Return the mutated hex so the existing caller flow in EditMapView.axaml.cs (HandleHexSelection → RefreshHex) re-renders the hex and updates neighbor edges.
• Ensure the ActiveEditMode setter's existing reset behavior (clearing hex-info state when leaving Cursor) continues to behave correctly with the new paint tool.

🤖 Prompt for AI agents

Goal: add a single combined toolbar tool that paints road on non-water hexes and
bridge on water hexes, non-destructively.

- Add a `RoadBridge` value to `src/MakaMek.MapEditor/Models/ToolType.cs`.
- In `EditMapViewModel.LoadTerrains()`, add an `AvailableTools.Add(new
ToolItem(...ToolType.RoadBridge..., imagePath: roadbridge icon))` entry
alongside the existing RaiseLevel/water-depth tools; this tool carries no
`Terrain` payload since the terrain choice is made in the paint handler.
- No change to the `SelectedTool` setter is required beyond it copying
`ToolType.RoadBridge` into `ActiveEditMode`.
- Add a `case ToolType.RoadBridge:` branch in
`EditMapViewModel.HandleHexSelection`.
- Decision logic: if the hex has water terrain (`HasTerrain(Water)`), add a
bridge terrain with default level and default construction factor; otherwise add
a road terrain. Use `AddTerrain` (not `ReplaceTerrains`) so underlying terrain
is preserved; guard against duplicating an already-present road/bridge.
- Return the mutated hex so the existing caller flow in `EditMapView.axaml.cs`
(`HandleHexSelection` → `RefreshHex`) re-renders the hex and updates neighbor
edges.
- Ensure the `ActiveEditMode` setter's existing reset behavior (clearing
hex-info state when leaving Cursor) continues to work correctly with the new
paint tool.

Phase 3: HexInfo Popup Interactivity and Road↔Bridge Conversion

Extend the read-only hex projection and the popup with controls to raise/lower the bridge level and adjust its construction factor, including automatic conversion between road and bridge as the level crosses zero over non-water terrain.

Task 1: Extend the hex projection for road/bridge state

Surface the new state to the UI, mirroring the existing water-depth projection.

• In src/MakaMek.MapEditor/ViewModels/Wrappers/HexViewModel.cs, add read-only properties (e.g. HasRoadBridge, IsBridge, BridgeLevel, ConstructionFactor) populated in UpdateFromHex from the hex's road/bridge terrain, following the WaterDepth/IsWater pattern (raise PropertyChanged for each).

Task 2: Add popup commands and conversion logic

Provide the raise/lower and construction-factor commands, and the automatic road↔bridge conversion.

• In EditMapViewModel, add IAsyncCommands (e.g. RaiseBridgeLevelCommand, LowerBridgeLevelCommand, IncreaseConstructionFactorCommand, DecreaseConstructionFactorCommand) mirroring the existing water-depth popup commands: mutate _currentHex, refresh HexViewModel via UpdateFromHex, and fire the HexUpdated event so the canvas refreshes.
• Conversion rules in these commands:
  • Raising the level of a road (level 0) converts it into a bridge at level 1 (remove road terrain, add bridge terrain carrying a level and default construction factor).
  • Lowering a bridge's level to 0 over non-water terrain converts it back into a road (remove bridge terrain, add road terrain). Over water, keep it a bridge (do not convert; enforce a sensible minimum level).
  • Construction-factor adjustments apply only to bridges and are bounded to a valid range.
• Reuse the same mutation logic between the popup commands and, where sensible, the paint handler to avoid divergence between the two code paths.

Task 3: Add the popup UI rows

Add the interactive rows to the HexInfo overlay.

• In src/MakaMek.MapEditor/Controls/HexInfoOverlay.axaml, add a bridge/road section gated by an IsVisible binding to HexViewModel.HasRoadBridge (and a sub-row gated by IsBridge), mirroring the existing water-depth row: a BridgeLevel label/value with ▲/▼ buttons bound to the raise/lower commands, and a ConstructionFactor label/value with ▲/▼ buttons bound to the construction-factor commands.
• No logic in HexInfoOverlay.axaml.cs (keep the trivial code-behind pattern).

🤖 Prompt for AI agents

Goal: extend the read-only hex projection and HexInfo popup with bridge
level/construction-factor controls, including automatic road↔bridge conversion
as the level crosses zero.

- In `src/MakaMek.MapEditor/ViewModels/Wrappers/HexViewModel.cs`, add read-only
properties (`HasRoadBridge`, `IsBridge`, `BridgeLevel`, `ConstructionFactor`)
populated in `UpdateFromHex` from the hex's road/bridge terrain, following the
`WaterDepth`/`IsWater` pattern; raise `PropertyChanged` for each.
- In `EditMapViewModel`, add `IAsyncCommand`s (`RaiseBridgeLevelCommand`,
`LowerBridgeLevelCommand`, `IncreaseConstructionFactorCommand`,
`DecreaseConstructionFactorCommand`) mirroring the existing water-depth popup
commands: mutate `_currentHex`, refresh `HexViewModel` via `UpdateFromHex`, and
fire the `HexUpdated` event so the canvas refreshes.
- Implement conversion rules within these commands:
- Raising the level of a road (level 0) converts it into a bridge at level 1
(remove road terrain, add bridge terrain carrying a level and default
construction factor).
- Lowering a bridge's level to 0 over non-water terrain converts it back into a
road (remove bridge terrain, add road terrain). Over water, keep it a bridge (do
not convert; enforce a sensible minimum level).
- Construction-factor adjustments apply only to bridges and are bounded to a
valid range.
- Reuse the same mutation logic between the popup commands and, where sensible,
the paint handler from Phase 2 to avoid divergence.
- In `src/MakaMek.MapEditor/Controls/HexInfoOverlay.axaml`, add a bridge/road
section gated by an `IsVisible` binding to `HexViewModel.HasRoadBridge` (and a
sub-row gated by `IsBridge`), mirroring the existing water-depth row: a
`BridgeLevel` label/value with ▲/▼ buttons bound to raise/lower commands, and a
`ConstructionFactor` label/value with ▲/▼ buttons bound to the
construction-factor commands.
- Keep `HexInfoOverlay.axaml.cs` free of logic (trivial code-behind pattern).

Phase 4: Tests

Cover the new tool and popup behaviors using the project's established testing conventions (xUnit + Shouldly + NSubstitute, real Hex/BattleMap, SelectHexViaCursor helper).

Task 1: Tool and conversion tests

Validate paint decisions and conversion rules.

• In tests/MakaMek.MapEditor.Test/ViewModels/EditMapViewModelTests.cs, add tests: RoadBridge tool on a non-water hex adds road (preserving underlying terrain); on a water hex adds bridge; commands raise/lower bridge level and adjust construction factor; raising a road converts to bridge; lowering a bridge to 0 over non-water converts to road; bridge over water does not convert; all mutating commands fire HexUpdated.
• Use real BattleMap/Hex objects and the existing SelectHexViaCursor helper (with a ToolItem of the new ToolType.RoadBridge for the paint path).

Task 2: HexViewModel projection tests

Validate the new projection properties.

• In tests/MakaMek.MapEditor.Test/ViewModels/Wrappers/HexViewModelTests.cs, add UpdateFromHex tests asserting HasRoadBridge/IsBridge/BridgeLevel/ConstructionFactor and the corresponding PropertyChanged notifications, mirroring the existing WaterDepth/IsWater tests.

🤖 Prompt for AI agents

Goal: add test coverage for the new tool, conversion logic, and projection
properties using established conventions (xUnit, Shouldly, NSubstitute, real
`Hex`/`BattleMap`, `SelectHexViaCursor` helper).

- In `tests/MakaMek.MapEditor.Test/ViewModels/EditMapViewModelTests.cs`, add
tests covering: RoadBridge tool on a non-water hex adds road while preserving
underlying terrain; on a water hex adds bridge; commands raise/lower bridge
level and adjust construction factor; raising a road converts it to a bridge;
lowering a bridge to 0 over non-water converts it back to a road; bridge over
water does not convert; all mutating commands fire `HexUpdated`.
- Use real `BattleMap`/`Hex` objects and the existing `SelectHexViaCursor`
helper (using a `ToolItem` of the new `ToolType.RoadBridge` for the paint path).
- In `tests/MakaMek.MapEditor.Test/ViewModels/Wrappers/HexViewModelTests.cs`,
add `UpdateFromHex` tests asserting
`HasRoadBridge`/`IsBridge`/`BridgeLevel`/`ConstructionFactor` values and the
corresponding `PropertyChanged` notifications, mirroring the existing
`WaterDepth`/`IsWater` tests.

Research

src/MakaMek.MapEditor is an Avalonia MVVM editor that consumes the domain model (Hex, Terrain, MakaMekTerrains) from the external NuGet package Sanet.MakaMek.Map (0.60.10-preview) — this package is not editable from the repo. Editor-side terrain support is manually wired via a hard-coded KnownTerrains list and LoadTerrains() in EditMapViewModel, which populates an AvailableTools toolbar of ToolItems keyed by a ToolType enum. Painting/mutation is dispatched through HandleHexSelection (canvas clicks) with a parallel set of popup commands (RaiseLevelCommand, IncreaseWaterDepthCommand, etc.) that mutate a _currentHex, update the read-only HexViewModel projection, and fire a HexUpdated event that triggers RefreshHex on the canvas. The HexInfoOverlay popup already contains editable elevation and water-depth rows (▲/▼ buttons bound to those commands), and a road.png asset already ships (unused). Actual pixel rendering lives inside the external HexControl driven by the Hex terrain collection.

File-Level Change Summary and Follow-up Prompts

Impacted files and the nature of each change:

• src/MakaMek.MapEditor/MakaMek.MapEditor.csproj (and .Browser csproj): verify or bump Sanet.MakaMek.* package versions if road/bridge/construction-factor domain types are absent.
• src/MakaMek.MapEditor/Models/ToolType.cs: add RoadBridge enum value.
• src/MakaMek.MapEditor/ViewModels/EditMapViewModel.cs: register road/bridge terrain awareness; add RoadBridge ToolItem in LoadTerrains(); add HandleHexSelection case with water-vs-non-water decision; add bridge-level and construction-factor commands with road↔bridge conversion logic; reuse mutation helpers.
• src/MakaMek.MapEditor/ViewModels/Wrappers/HexViewModel.cs: add HasRoadBridge/IsBridge/BridgeLevel/ConstructionFactor populated in UpdateFromHex.
• src/MakaMek.MapEditor/Controls/HexInfoOverlay.axaml: add road/bridge section with level and construction-factor rows and ▲/▼ buttons.
• src/MakaMek.MapEditor/Assets/tools/roadbridge.png (new) and possibly a bridge terrain visual asset.
• Localization source: new EditMap_* keys for the tool, labels, and button tooltips.
• tests/MakaMek.MapEditor.Test/ViewModels/EditMapViewModelTests.cs and .../Wrappers/HexViewModelTests.cs: new tests per Phase 4.

Prompts/instructions for follow-up agents:

• Before wiring, confirm the exact public API of the road/bridge terrain classes in Sanet.MakaMek.Map (constructor signatures, how level and construction factor are represented, and the MakaMekTerrains enum members). If absent, upgrade the package and re-verify.
• Confirm how the external HexControl renders road/bridge terrains (whether it draws them automatically from the hex terrain collection or needs an additional render-config flag), and adjust HexRenderConfigurationViewModel/EditMapView.axaml.cs only if the control requires it.
• Decide on default bridge level, default/min/max construction factor, and minimum bridge level over water; encode these as named constants.

---

🚀 Next Steps

🤖 All AI agent prompts combined

Task: 1

Goal: make the road/bridge domain concept available to the editor by
confirming/upgrading the referenced package and registering terrain awareness
plus supporting assets/localization.

- Verify `Sanet.MakaMek.Map` (referenced in
`src/MakaMek.MapEditor/MakaMek.MapEditor.csproj`) exposes `RoadTerrain`,
`BridgeTerrain` (or equivalent terrain carrying a level/height), the
corresponding `MakaMekTerrains` enum members, and a construction-factor property
on the bridge terrain.
- If any of these are missing, bump the `Sanet.MakaMek.*` package versions
consistently across `src/MakaMek.MapEditor/MakaMek.MapEditor.csproj` and
`src/MakaMek.MapEditor.Browser/MakaMek.MapEditor.Browser.csproj` to a version
that provides them.
- Confirm the semantic model: road = ground-level construction; bridge =
elevated construction with a level and construction factor. This mapping drives
later conversion logic.
- In `src/MakaMek.MapEditor/ViewModels/EditMapViewModel.cs`, extend the
hard-coded `KnownTerrains`/terrain-awareness so the editor recognizes road and
bridge terrains for rendering and info display. Note these will be applied via a
dedicated tool rather than the generic terrain painter, so they should not
necessarily appear as ordinary paint-terrain entries (handled in Phase 2).
- Add a combined tool icon asset under `src/MakaMek.MapEditor/Assets/tools/`
(e.g. `roadbridge.png`); the existing `Assets/terrain/road.png` may be
reused/adapted, but add a bridge visual asset if the toolbar/info UI needs one.
- Add localization keys (e.g. `EditMap_RoadBridge`, `EditMap_BridgeLevel`,
`EditMap_ConstructionFactor`, `EditMap_RaiseBridge`, `EditMap_LowerBridge`,
`EditMap_IncreaseConstructionFactor`, `EditMap_DecreaseConstructionFactor`) in
the localization source used by
`MakaMekMapEditorFakeLocalizationService`/`ILocalizationService`.
===============================================================================

Task: 2

Goal: add a single combined toolbar tool that paints road on non-water hexes and
bridge on water hexes, non-destructively.

- Add a `RoadBridge` value to `src/MakaMek.MapEditor/Models/ToolType.cs`.
- In `EditMapViewModel.LoadTerrains()`, add an `AvailableTools.Add(new
ToolItem(...ToolType.RoadBridge..., imagePath: roadbridge icon))` entry
alongside the existing RaiseLevel/water-depth tools; this tool carries no
`Terrain` payload since the terrain choice is made in the paint handler.
- No change to the `SelectedTool` setter is required beyond it copying
`ToolType.RoadBridge` into `ActiveEditMode`.
- Add a `case ToolType.RoadBridge:` branch in
`EditMapViewModel.HandleHexSelection`.
- Decision logic: if the hex has water terrain (`HasTerrain(Water)`), add a
bridge terrain with default level and default construction factor; otherwise add
a road terrain. Use `AddTerrain` (not `ReplaceTerrains`) so underlying terrain
is preserved; guard against duplicating an already-present road/bridge.
- Return the mutated hex so the existing caller flow in `EditMapView.axaml.cs`
(`HandleHexSelection` → `RefreshHex`) re-renders the hex and updates neighbor
edges.
- Ensure the `ActiveEditMode` setter's existing reset behavior (clearing
hex-info state when leaving Cursor) continues to work correctly with the new
paint tool.
===============================================================================

Task: 3

Goal: extend the read-only hex projection and HexInfo popup with bridge
level/construction-factor controls, including automatic road↔bridge conversion
as the level crosses zero.

- In `src/MakaMek.MapEditor/ViewModels/Wrappers/HexViewModel.cs`, add read-only
properties (`HasRoadBridge`, `IsBridge`, `BridgeLevel`, `ConstructionFactor`)
populated in `UpdateFromHex` from the hex's road/bridge terrain, following the
`WaterDepth`/`IsWater` pattern; raise `PropertyChanged` for each.
- In `EditMapViewModel`, add `IAsyncCommand`s (`RaiseBridgeLevelCommand`,
`LowerBridgeLevelCommand`, `IncreaseConstructionFactorCommand`,
`DecreaseConstructionFactorCommand`) mirroring the existing water-depth popup
commands: mutate `_currentHex`, refresh `HexViewModel` via `UpdateFromHex`, and
fire the `HexUpdated` event so the canvas refreshes.
- Implement conversion rules within these commands:
- Raising the level of a road (level 0) converts it into a bridge at level 1
(remove road terrain, add bridge terrain carrying a level and default
construction factor).
- Lowering a bridge's level to 0 over non-water terrain converts it back into a
road (remove bridge terrain, add road terrain). Over water, keep it a bridge (do
not convert; enforce a sensible minimum level).
- Construction-factor adjustments apply only to bridges and are bounded to a
valid range.
- Reuse the same mutation logic between the popup commands and, where sensible,
the paint handler from Phase 2 to avoid divergence.
- In `src/MakaMek.MapEditor/Controls/HexInfoOverlay.axaml`, add a bridge/road
section gated by an `IsVisible` binding to `HexViewModel.HasRoadBridge` (and a
sub-row gated by `IsBridge`), mirroring the existing water-depth row: a
`BridgeLevel` label/value with ▲/▼ buttons bound to raise/lower commands, and a
`ConstructionFactor` label/value with ▲/▼ buttons bound to the
construction-factor commands.
- Keep `HexInfoOverlay.axaml.cs` free of logic (trivial code-behind pattern).
===============================================================================

Task: 4

Goal: add test coverage for the new tool, conversion logic, and projection
properties using established conventions (xUnit, Shouldly, NSubstitute, real
`Hex`/`BattleMap`, `SelectHexViaCursor` helper).

- In `tests/MakaMek.MapEditor.Test/ViewModels/EditMapViewModelTests.cs`, add
tests covering: RoadBridge tool on a non-water hex adds road while preserving
underlying terrain; on a water hex adds bridge; commands raise/lower bridge
level and adjust construction factor; raising a road converts it to a bridge;
lowering a bridge to 0 over non-water converts it back to a road; bridge over
water does not convert; all mutating commands fire `HexUpdated`.
- Use real `BattleMap`/`Hex` objects and the existing `SelectHexViaCursor`
helper (using a `ToolItem` of the new `ToolType.RoadBridge` for the paint path).
- In `tests/MakaMek.MapEditor.Test/ViewModels/Wrappers/HexViewModelTests.cs`,
add `UpdateFromHex` tests asserting
`HasRoadBridge`/`IsBridge`/`BridgeLevel`/`ConstructionFactor` values and the
corresponding `PropertyChanged` notifications, mirroring the existing
`WaterDepth`/`IsWater` tests.

💡 Iterate on the plan with: `@coderabbitai` <feedback>

Example Feedback
- `@coderabbitai` You can skip phase 3. Add a simple unit test case for phase 2.
- `@coderabbitai` For design choice 1 go ahead with option 3 and replan.

---

💬 Have feedback or questions? Drop into our discord!

[anton-makarevich]

@coderabbitai plan

[coderabbitai]

Coding Plan

Summary

• Treat road and bridge as two states of the same construction concept — road at ground level, bridge when elevated or over water — sourced from the Sanet.MakaMek.Map package.
• Add a single RoadBridge toolbar tool whose paint handler chooses bridge over water and road otherwise, applied as an overlay that preserves underlying terrain.
• Extend the existing HexInfo popup and HexViewModel (mirroring the water-depth pattern) with bridge-level and construction-factor controls, plus automatic road↔bridge conversion as the level crosses zero over non-water terrain.
• Add tests following established conventions (real Hex/BattleMap, NSubstitute services, HexUpdated assertions).

Design Choices

Design Choice 1: Does `Sanet.MakaMek.Map` already expose Road/Bridge terrain types and a construction-factor property, or is a package upgrade required?

Options Considered:

1. The current pinned package version (0.60.10-preview) already ships RoadTerrain, BridgeTerrain, MakaMekTerrains.Road/Bridge, and a construction-factor/height API — only MapEditor-side wiring is needed.
2. The types do not yet exist and the Sanet.MakaMek.Map (and sibling Sanet.MakaMek.*) packages must be upgraded to a version that provides them before wiring.

Chosen Option: 1

Rationale: Option 1 as the primary path (verify the pinned version exposes the types and wire against them); fall back to Option 2 (bump all Sanet.MakaMek.* package versions in the .csproj files to the earliest version providing these types) if verification shows the types are missing. Rationale: minimizes churn and keeps all editor-domain types sourced from the package as the codebase intends. Road/Bridge/ConstructionFactor concepts do not appear anywhere in this repo, and the package source cannot be inspected in the sandbox. The editor cannot define domain terrain classes itself; they must come from the package.

Design Choice 2: Does the external `HexControl` render road/bridge terrains automatically from the hex terrain collection, or does it require an extra render-config flag?

Options Considered:

1. HexControl draws any terrain present in the hex collection (as it does for existing terrains), so no render-config change is needed.
2. Road/bridge require an additional flag on HexRenderConfiguration to be drawn.

Chosen Option: 1

Rationale: Option 1 as the primary path (rely on the existing terrain-collection-driven rendering); only adjust HexRenderConfigurationViewModel/EditMapView.axaml.cs if verification shows the control requires an explicit flag. Rationale: matches how all currently-supported terrains render without editor-side render flags. Rendering lives in the external Sanet.MakaMek.Avalonia.Controls package and cannot be inspected in the sandbox.

💡 User Tips

Regenerate the plan with different choices with @coderabbitai <feedback>.

Implementation Steps

Phase 1: Domain Readiness and Terrain Registration

Establish the road/bridge terrain types as first-class, paint-registered terrains in the editor so the model can carry them, the toolbar can surface them, and the external HexControl can render them. This phase is about making the domain concept available to the rest of the editor.

Task 1: Confirm/enable Road and Bridge domain terrain types

Verify the terrain classes and enum members the feature depends on exist in the referenced package; upgrade if they do not.

• Verify that Sanet.MakaMek.Map (as referenced in src/MakaMek.MapEditor/MakaMek.MapEditor.csproj) exposes RoadTerrain, BridgeTerrain (or an equivalent single terrain carrying a level/height), corresponding MakaMekTerrains enum members, and a construction-factor property on the bridge terrain — including their constructor signatures and how level and construction factor are represented.
• If any are missing, bump the Sanet.MakaMek.* package versions consistently across src/MakaMek.MapEditor/MakaMek.MapEditor.csproj and src/MakaMek.MapEditor.Browser/MakaMek.MapEditor.Browser.csproj to a version that provides them.
• Confirm the semantic model: a road is the ground-level construction; a bridge is the elevated construction carrying a level and a construction factor. This mapping drives the conversion logic in later phases.
• Decide on and record named constants for default bridge level, default/min/max construction factor, and minimum bridge level over water; these are consumed by the paint handler and popup commands in later phases.

Task 2: Register road/bridge terrains and add the tool icon

Wire the new terrain(s) into the editor's terrain awareness and provide a toolbar icon.

• In src/MakaMek.MapEditor/ViewModels/EditMapViewModel.cs, extend the hard-coded KnownTerrains/terrain-awareness so the editor recognizes road and bridge terrains for rendering and info display (note: these will be applied via a dedicated tool rather than the generic terrain painter, so they should not necessarily appear as ordinary paint-terrain entries — see Phase 2).
• Add a combined tool icon asset under src/MakaMek.MapEditor/Assets/tools/ (e.g. roadbridge.png); the existing Assets/terrain/road.png may be reused/adapted, but a bridge visual asset does not yet exist and must be added if the toolbar/info UI needs one.
• Add localization keys (e.g. EditMap_RoadBridge, EditMap_BridgeLevel, EditMap_ConstructionFactor, EditMap_RaiseBridge, EditMap_LowerBridge, EditMap_IncreaseConstructionFactor, EditMap_DecreaseConstructionFactor) in the localization source used by MakaMekMapEditorFakeLocalizationService/ILocalizationService.

🤖 Prompt for AI agents

Goal: make the road/bridge domain concept available to the editor by
confirming/upgrading the referenced package and registering terrain awareness
plus supporting assets/localization.

- Verify `Sanet.MakaMek.Map` (referenced in
`src/MakaMek.MapEditor/MakaMek.MapEditor.csproj`) exposes `RoadTerrain`,
`BridgeTerrain` (or equivalent terrain carrying a level/height), the
corresponding `MakaMekTerrains` enum members, and a construction-factor property
on the bridge terrain — including their constructor signatures and how level and
construction factor are represented.
- If any of these are missing, bump the `Sanet.MakaMek.*` package versions
consistently across `src/MakaMek.MapEditor/MakaMek.MapEditor.csproj` and
`src/MakaMek.MapEditor.Browser/MakaMek.MapEditor.Browser.csproj` to a version
that provides them.
- Confirm the semantic model: road = ground-level construction; bridge =
elevated construction with a level and construction factor. This mapping drives
later conversion logic.
- Decide on and record named constants for default bridge level, default/min/max
construction factor, and minimum bridge level over water, for use by the paint
handler and popup commands in later phases.
- In `src/MakaMek.MapEditor/ViewModels/EditMapViewModel.cs`, extend the
hard-coded `KnownTerrains`/terrain-awareness so the editor recognizes road and
bridge terrains for rendering and info display. Note these will be applied via a
dedicated tool rather than the generic terrain painter, so they should not
necessarily appear as ordinary paint-terrain entries (handled in Phase 2).
- Add a combined tool icon asset under `src/MakaMek.MapEditor/Assets/tools/`
(e.g. `roadbridge.png`); the existing `Assets/terrain/road.png` may be
reused/adapted, but add a bridge visual asset if the toolbar/info UI needs one.
- Add localization keys (e.g. `EditMap_RoadBridge`, `EditMap_BridgeLevel`,
`EditMap_ConstructionFactor`, `EditMap_RaiseBridge`, `EditMap_LowerBridge`,
`EditMap_IncreaseConstructionFactor`, `EditMap_DecreaseConstructionFactor`) in
the localization source used by
`MakaMekMapEditorFakeLocalizationService`/`ILocalizationService`.

Phase 2: Combined Road/Bridge Tool

Introduce a single toolbar tool that, on hex click, decides between road and bridge based on whether the hex already contains water, and applies the appropriate terrain non-destructively (as an overlay on top of existing terrain rather than replacing it).

Task 1: Add the RoadBridge tool type and toolbar entry

Expose the combined tool in the toolbar following the existing non-terrain-payload tool pattern.

• Add a RoadBridge value to src/MakaMek.MapEditor/Models/ToolType.cs.
• In EditMapViewModel.LoadTerrains(), add an AvailableTools.Add(new ToolItem(...ToolType.RoadBridge..., imagePath: roadbridge icon)) entry alongside the existing RaiseLevel/water-depth tools (these carry no Terrain payload; the terrain choice is made in the paint handler).
• No change to the SelectedTool setter is required beyond it copying ToolType.RoadBridge into ActiveEditMode, since the tool carries no Terrain payload.

Task 2: Implement road-vs-bridge paint logic

Apply the correct construction terrain when the tool is active and a hex is clicked.

• Add a case ToolType.RoadBridge: branch in EditMapViewModel.HandleHexSelection.
• Decision logic: if the hex has water terrain (HasTerrain(Water)), add a bridge terrain (default level and default construction factor); otherwise add a road terrain. Add the construction terrain on top of existing terrains (use AddTerrain, not ReplaceTerrains) so the underlying terrain is preserved; guard against duplicating an already-present road/bridge.
• Return the mutated hex so the existing caller flow in EditMapView.axaml.cs (HandleHexSelection → RefreshHex) re-renders the hex and updates neighbor edges.
• Ensure the ActiveEditMode setter's existing reset behavior (clearing hex-info state when leaving Cursor) continues to behave correctly with the new paint tool.

🤖 Prompt for AI agents

Goal: add a single combined toolbar tool that paints road on non-water hexes and
bridge on water hexes, non-destructively.

- Add a `RoadBridge` value to `src/MakaMek.MapEditor/Models/ToolType.cs`.
- In `EditMapViewModel.LoadTerrains()`, add an `AvailableTools.Add(new
ToolItem(...ToolType.RoadBridge..., imagePath: roadbridge icon))` entry
alongside the existing RaiseLevel/water-depth tools; this tool carries no
`Terrain` payload since the terrain choice is made in the paint handler.
- No change to the `SelectedTool` setter is required beyond it copying
`ToolType.RoadBridge` into `ActiveEditMode`.
- Add a `case ToolType.RoadBridge:` branch in
`EditMapViewModel.HandleHexSelection`.
- Decision logic: if the hex has water terrain (`HasTerrain(Water)`), add a
bridge terrain with default level and default construction factor; otherwise add
a road terrain. Use `AddTerrain` (not `ReplaceTerrains`) so underlying terrain
is preserved; guard against duplicating an already-present road/bridge.
- Return the mutated hex so the existing caller flow in `EditMapView.axaml.cs`
(`HandleHexSelection` → `RefreshHex`) re-renders the hex and updates neighbor
edges.
- Ensure the `ActiveEditMode` setter's existing reset behavior (clearing
hex-info state when leaving Cursor) continues to work correctly with the new
paint tool.

Phase 3: HexInfo Popup Interactivity and Road↔Bridge Conversion

Extend the read-only hex projection and the popup with controls to raise/lower the bridge level and adjust its construction factor, including automatic conversion between road and bridge as the level crosses zero over non-water terrain.

Task 1: Extend the hex projection for road/bridge state

Surface the new state to the UI, mirroring the existing water-depth projection.

• In src/MakaMek.MapEditor/ViewModels/Wrappers/HexViewModel.cs, add read-only properties (e.g. HasRoadBridge, IsBridge, BridgeLevel, ConstructionFactor) populated in UpdateFromHex from the hex's road/bridge terrain, following the WaterDepth/IsWater pattern (raise PropertyChanged for each).

Task 2: Add popup commands and conversion logic

Provide the raise/lower and construction-factor commands, and the automatic road↔bridge conversion.

• In EditMapViewModel, add IAsyncCommands (e.g. RaiseBridgeLevelCommand, LowerBridgeLevelCommand, IncreaseConstructionFactorCommand, DecreaseConstructionFactorCommand) mirroring the existing water-depth popup commands: mutate _currentHex, refresh HexViewModel via UpdateFromHex, and fire the HexUpdated event so the canvas refreshes.
• Conversion rules in these commands (using the constants defined in Task 1.1):
  • Raising the level of a road (level 0) converts it into a bridge at level 1 (remove road terrain, add bridge terrain carrying a level and default construction factor).
  • Lowering a bridge's level to 0 over non-water terrain converts it back into a road (remove bridge terrain, add road terrain). Over water, keep it a bridge (do not convert; enforce the minimum-level-over-water constant).
  • Construction-factor adjustments apply only to bridges and are bounded to the valid range.
• Reuse the same mutation logic between the popup commands and, where sensible, the paint handler to avoid divergence between the two code paths.

Task 3: Add the popup UI rows

Add the interactive rows to the HexInfo overlay.

• In src/MakaMek.MapEditor/Controls/HexInfoOverlay.axaml, add a bridge/road section gated by an IsVisible binding to HexViewModel.HasRoadBridge (and a sub-row gated by IsBridge), mirroring the existing water-depth row: a BridgeLevel label/value with ▲/▼ buttons bound to the raise/lower commands, and a ConstructionFactor label/value with ▲/▼ buttons bound to the construction-factor commands.
• No logic in HexInfoOverlay.axaml.cs (keep the trivial code-behind pattern).

🤖 Prompt for AI agents

Goal: extend the read-only hex projection and HexInfo popup with bridge
level/construction-factor controls, including automatic road↔bridge conversion
as the level crosses zero.

- In `src/MakaMek.MapEditor/ViewModels/Wrappers/HexViewModel.cs`, add read-only
properties (`HasRoadBridge`, `IsBridge`, `BridgeLevel`, `ConstructionFactor`)
populated in `UpdateFromHex` from the hex's road/bridge terrain, following the
`WaterDepth`/`IsWater` pattern; raise `PropertyChanged` for each.
- In `EditMapViewModel`, add `IAsyncCommand`s (`RaiseBridgeLevelCommand`,
`LowerBridgeLevelCommand`, `IncreaseConstructionFactorCommand`,
`DecreaseConstructionFactorCommand`) mirroring the existing water-depth popup
commands: mutate `_currentHex`, refresh `HexViewModel` via `UpdateFromHex`, and
fire the `HexUpdated` event so the canvas refreshes.
- Implement conversion rules within these commands (using the constants defined
in Phase 1):
- Raising the level of a road (level 0) converts it into a bridge at level 1
(remove road terrain, add bridge terrain carrying a level and default
construction factor).
- Lowering a bridge's level to 0 over non-water terrain converts it back into a
road (remove bridge terrain, add road terrain). Over water, keep it a bridge (do
not convert; enforce the minimum-level-over-water constant).
- Construction-factor adjustments apply only to bridges and are bounded to the
valid range.
- Reuse the same mutation logic between the popup commands and, where sensible,
the paint handler from Phase 2 to avoid divergence.
- In `src/MakaMek.MapEditor/Controls/HexInfoOverlay.axaml`, add a bridge/road
section gated by an `IsVisible` binding to `HexViewModel.HasRoadBridge` (and a
sub-row gated by `IsBridge`), mirroring the existing water-depth row: a
`BridgeLevel` label/value with ▲/▼ buttons bound to raise/lower commands, and a
`ConstructionFactor` label/value with ▲/▼ buttons bound to the
construction-factor commands.
- Keep `HexInfoOverlay.axaml.cs` free of logic (trivial code-behind pattern).

Phase 4: Tests

Cover the new tool and popup behaviors using the project's established testing conventions (xUnit + Shouldly + NSubstitute, real Hex/BattleMap, SelectHexViaCursor helper).

Task 1: Tool and conversion tests

Validate paint decisions and conversion rules.

• In tests/MakaMek.MapEditor.Test/ViewModels/EditMapViewModelTests.cs, add tests: RoadBridge tool on a non-water hex adds road (preserving underlying terrain); on a water hex adds bridge; commands raise/lower bridge level and adjust construction factor; raising a road converts to bridge; lowering a bridge to 0 over non-water converts to road; bridge over water does not convert; all mutating commands fire HexUpdated.
• Use real BattleMap/Hex objects and the existing SelectHexViaCursor helper (with a ToolItem of the new ToolType.RoadBridge for the paint path).

Task 2: HexViewModel projection tests

Validate the new projection properties.

• In tests/MakaMek.MapEditor.Test/ViewModels/Wrappers/HexViewModelTests.cs, add UpdateFromHex tests asserting HasRoadBridge/IsBridge/BridgeLevel/ConstructionFactor and the corresponding PropertyChanged notifications, mirroring the existing WaterDepth/IsWater tests.

🤖 Prompt for AI agents

Goal: add test coverage for the new tool, conversion logic, and projection
properties using established conventions (xUnit, Shouldly, NSubstitute, real
`Hex`/`BattleMap`, `SelectHexViaCursor` helper).

- In `tests/MakaMek.MapEditor.Test/ViewModels/EditMapViewModelTests.cs`, add
tests covering: RoadBridge tool on a non-water hex adds road while preserving
underlying terrain; on a water hex adds bridge; commands raise/lower bridge
level and adjust construction factor; raising a road converts it to a bridge;
lowering a bridge to 0 over non-water converts it back to a road; bridge over
water does not convert; all mutating commands fire `HexUpdated`.
- Use real `BattleMap`/`Hex` objects and the existing `SelectHexViaCursor`
helper (using a `ToolItem` of the new `ToolType.RoadBridge` for the paint path).
- In `tests/MakaMek.MapEditor.Test/ViewModels/Wrappers/HexViewModelTests.cs`,
add `UpdateFromHex` tests asserting
`HasRoadBridge`/`IsBridge`/`BridgeLevel`/`ConstructionFactor` values and the
corresponding `PropertyChanged` notifications, mirroring the existing
`WaterDepth`/`IsWater` tests.

Research

src/MakaMek.MapEditor is an Avalonia MVVM editor that consumes the domain model (Hex, Terrain, MakaMekTerrains) from the external NuGet package Sanet.MakaMek.Map (0.60.10-preview) — this package is not editable from the repo. Editor-side terrain support is manually wired via a hard-coded KnownTerrains list and LoadTerrains() in EditMapViewModel, which populates an AvailableTools toolbar of ToolItems keyed by a ToolType enum. Painting/mutation is dispatched through HandleHexSelection (canvas clicks) with a parallel set of popup commands (RaiseLevelCommand, IncreaseWaterDepthCommand, etc.) that mutate a _currentHex, update the read-only HexViewModel projection, and fire a HexUpdated event that triggers RefreshHex on the canvas. The HexInfoOverlay popup already contains editable elevation and water-depth rows (▲/▼ buttons bound to those commands), and a road.png asset already ships (unused). Actual pixel rendering lives inside the external HexControl driven by the Hex terrain collection.

---

🚀 Next Steps

🤖 All AI agent prompts combined

Task: 1

Goal: make the road/bridge domain concept available to the editor by
confirming/upgrading the referenced package and registering terrain awareness
plus supporting assets/localization.

- Verify `Sanet.MakaMek.Map` (referenced in
`src/MakaMek.MapEditor/MakaMek.MapEditor.csproj`) exposes `RoadTerrain`,
`BridgeTerrain` (or equivalent terrain carrying a level/height), the
corresponding `MakaMekTerrains` enum members, and a construction-factor property
on the bridge terrain — including their constructor signatures and how level and
construction factor are represented.
- If any of these are missing, bump the `Sanet.MakaMek.*` package versions
consistently across `src/MakaMek.MapEditor/MakaMek.MapEditor.csproj` and
`src/MakaMek.MapEditor.Browser/MakaMek.MapEditor.Browser.csproj` to a version
that provides them.
- Confirm the semantic model: road = ground-level construction; bridge =
elevated construction with a level and construction factor. This mapping drives
later conversion logic.
- Decide on and record named constants for default bridge level, default/min/max
construction factor, and minimum bridge level over water, for use by the paint
handler and popup commands in later phases.
- In `src/MakaMek.MapEditor/ViewModels/EditMapViewModel.cs`, extend the
hard-coded `KnownTerrains`/terrain-awareness so the editor recognizes road and
bridge terrains for rendering and info display. Note these will be applied via a
dedicated tool rather than the generic terrain painter, so they should not
necessarily appear as ordinary paint-terrain entries (handled in Phase 2).
- Add a combined tool icon asset under `src/MakaMek.MapEditor/Assets/tools/`
(e.g. `roadbridge.png`); the existing `Assets/terrain/road.png` may be
reused/adapted, but add a bridge visual asset if the toolbar/info UI needs one.
- Add localization keys (e.g. `EditMap_RoadBridge`, `EditMap_BridgeLevel`,
`EditMap_ConstructionFactor`, `EditMap_RaiseBridge`, `EditMap_LowerBridge`,
`EditMap_IncreaseConstructionFactor`, `EditMap_DecreaseConstructionFactor`) in
the localization source used by
`MakaMekMapEditorFakeLocalizationService`/`ILocalizationService`.
===============================================================================

Task: 2

Goal: add a single combined toolbar tool that paints road on non-water hexes and
bridge on water hexes, non-destructively.

- Add a `RoadBridge` value to `src/MakaMek.MapEditor/Models/ToolType.cs`.
- In `EditMapViewModel.LoadTerrains()`, add an `AvailableTools.Add(new
ToolItem(...ToolType.RoadBridge..., imagePath: roadbridge icon))` entry
alongside the existing RaiseLevel/water-depth tools; this tool carries no
`Terrain` payload since the terrain choice is made in the paint handler.
- No change to the `SelectedTool` setter is required beyond it copying
`ToolType.RoadBridge` into `ActiveEditMode`.
- Add a `case ToolType.RoadBridge:` branch in
`EditMapViewModel.HandleHexSelection`.
- Decision logic: if the hex has water terrain (`HasTerrain(Water)`), add a
bridge terrain with default level and default construction factor; otherwise add
a road terrain. Use `AddTerrain` (not `ReplaceTerrains`) so underlying terrain
is preserved; guard against duplicating an already-present road/bridge.
- Return the mutated hex so the existing caller flow in `EditMapView.axaml.cs`
(`HandleHexSelection` → `RefreshHex`) re-renders the hex and updates neighbor
edges.
- Ensure the `ActiveEditMode` setter's existing reset behavior (clearing
hex-info state when leaving Cursor) continues to work correctly with the new
paint tool.
===============================================================================

Task: 3

Goal: extend the read-only hex projection and HexInfo popup with bridge
level/construction-factor controls, including automatic road↔bridge conversion
as the level crosses zero.

- In `src/MakaMek.MapEditor/ViewModels/Wrappers/HexViewModel.cs`, add read-only
properties (`HasRoadBridge`, `IsBridge`, `BridgeLevel`, `ConstructionFactor`)
populated in `UpdateFromHex` from the hex's road/bridge terrain, following the
`WaterDepth`/`IsWater` pattern; raise `PropertyChanged` for each.
- In `EditMapViewModel`, add `IAsyncCommand`s (`RaiseBridgeLevelCommand`,
`LowerBridgeLevelCommand`, `IncreaseConstructionFactorCommand`,
`DecreaseConstructionFactorCommand`) mirroring the existing water-depth popup
commands: mutate `_currentHex`, refresh `HexViewModel` via `UpdateFromHex`, and
fire the `HexUpdated` event so the canvas refreshes.
- Implement conversion rules within these commands (using the constants defined
in Phase 1):
- Raising the level of a road (level 0) converts it into a bridge at level 1
(remove road terrain, add bridge terrain carrying a level and default
construction factor).
- Lowering a bridge's level to 0 over non-water terrain converts it back into a
road (remove bridge terrain, add road terrain). Over water, keep it a bridge (do
not convert; enforce the minimum-level-over-water constant).
- Construction-factor adjustments apply only to bridges and are bounded to the
valid range.
- Reuse the same mutation logic between the popup commands and, where sensible,
the paint handler from Phase 2 to avoid divergence.
- In `src/MakaMek.MapEditor/Controls/HexInfoOverlay.axaml`, add a bridge/road
section gated by an `IsVisible` binding to `HexViewModel.HasRoadBridge` (and a
sub-row gated by `IsBridge`), mirroring the existing water-depth row: a
`BridgeLevel` label/value with ▲/▼ buttons bound to raise/lower commands, and a
`ConstructionFactor` label/value with ▲/▼ buttons bound to the
construction-factor commands.
- Keep `HexInfoOverlay.axaml.cs` free of logic (trivial code-behind pattern).
===============================================================================

Task: 4

Goal: add test coverage for the new tool, conversion logic, and projection
properties using established conventions (xUnit, Shouldly, NSubstitute, real
`Hex`/`BattleMap`, `SelectHexViaCursor` helper).

- In `tests/MakaMek.MapEditor.Test/ViewModels/EditMapViewModelTests.cs`, add
tests covering: RoadBridge tool on a non-water hex adds road while preserving
underlying terrain; on a water hex adds bridge; commands raise/lower bridge
level and adjust construction factor; raising a road converts it to a bridge;
lowering a bridge to 0 over non-water converts it back to a road; bridge over
water does not convert; all mutating commands fire `HexUpdated`.
- Use real `BattleMap`/`Hex` objects and the existing `SelectHexViaCursor`
helper (using a `ToolItem` of the new `ToolType.RoadBridge` for the paint path).
- In `tests/MakaMek.MapEditor.Test/ViewModels/Wrappers/HexViewModelTests.cs`,
add `UpdateFromHex` tests asserting
`HasRoadBridge`/`IsBridge`/`BridgeLevel`/`ConstructionFactor` values and the
corresponding `PropertyChanged` notifications, mirroring the existing
`WaterDepth`/`IsWater` tests.

💡 Iterate on the plan with: `@coderabbitai` <feedback>

Example Feedback
- `@coderabbitai` You can skip phase 3. Add a simple unit test case for phase 2.
- `@coderabbitai` For design choice 1 go ahead with option 3 and replan.

---

💬 Have feedback or questions? Drop into our discord!