Add fuel logistics, modular construction, and pad docking

SESSION.md

@@ -108,15 +108,27 @@ The backend simulation already includes:
 
 - autonomous ships
 - orbital travel
-- docking and undocking
+- pad-based docking and undocking
+  - stations expose docking capacity through installed dock-bay modules
+  - ships reserve an empty pad before docking
+  - ships wait in a holding pattern when no pad is available
 - mining and refinery delivery
 - module-gated ship and station capabilities
-  - ships require fitted modules such as reactor, capacitor, and mining or gun turrets
-  - stations require fitted modules such as power, refinery, and storage modules
+  - ships require fitted modules such as reactor, capacitor, mining turret, gas extractor, or gun turrets
+  - stations require installed modules such as power, docking, refinery, fuel processing, and storage modules
 - fuel-to-energy power simulation
-  - ship reactors consume `gas` fuel to charge capacitors
-  - station power cores consume `gas` fuel to charge station energy buffers
+  - gas clouds provide raw `gas`
+  - station fuel processors convert `gas` into `fuel`
+  - ship reactors consume `fuel` to charge capacitors
+  - station power cores consume `fuel` to charge station energy buffers
   - powered actions stop when fuel and energy are depleted
+- constructor-led station module construction
+  - stations now track installed modules per instance instead of relying only on static constructible definitions
+  - module construction uses station inventory plus timed build progress
+- explicit action timing in the control loop
+  - mining now runs on a fixed cycle
+  - warp and FTL travel require spool time
+  - docking and undocking have explicit durations
 - refining / fabrication
 - faction growth through ship and outpost production
 - pirate pressure and combat
@@ -129,7 +141,7 @@ The backend simulation already includes:
   - systems in galaxy space
   - in-system entities in local space
 - item-based inventories for ships and stations
-  - ore, refined metals, gas fuel, and cargo now flow through per-item inventories instead of ad hoc stock fields
+  - ore, refined metals, raw gas, fuel, and cargo now flow through per-item inventories instead of ad hoc stock fields
 
 The runtime model still follows the intended layered control architecture:
 
@@ -164,13 +176,20 @@ The runtime model still follows the intended layered control architecture:
   - one modular station
   - one constructor ship
   - one mining ship
+- added a gas mining ship for bootstrap fuel logistics
 - moved the starting ships close to the `helios` star and next to each other
 - added modular ship and station data
   - new station power and storage modules
-  - new ship reactor, capacitor, mining turret, and gun turret modules
+  - new fuel processing and docking bay modules
+  - new ship reactor, capacitor, mining turret, gas extractor, and gun turret modules
 - refactored simulation inventories to per-item storage
   - stations and ships now replicate inventories instead of specialized ore/refined/cargo counters
-- added fuel-driven power generation and energy consumption in the simulation loop
+- split raw `gas` from burnable `fuel` in the simulation loop
+- added module recipe data and per-station installed-module runtime state
+- added constructor-led station module construction for the bootstrap station
+- added gas harvesting, gas-to-fuel processing, and explicit ship refueling behavior
+- reworked docking into pad reservation with visible stand-off positions instead of snapping ships into station centers
+- added action timing for mining cycles, warp / FTL spool-up, and undocking
 - replaced the viewer bottom faction strip with a horizontal ship-card debugging rail
 - added movable, resizable, multi-window history panels in the viewer
 - fixed the auto-miner undock controller transition
@@ -190,9 +209,14 @@ The runtime model still follows the intended layered control architecture:
 - the galaxy is much larger now, so viewer performance and visual density need active tuning
 - moon rendering is procedural from counts, not authored moon-by-moon data
 - resource extraction behavior still treats all resource nodes generically
-- item inventories exist, but storage enforcement and module-slot restrictions are still lightweight
-  - cargo/storage compatibility is mostly data-convention driven
+- item inventories exist, but storage/module restrictions are still partial
+  - station storage capacity is now enforced by storage class and installed module
+  - ship cargo compatibility is still mostly data-convention driven
   - hull-specific module restrictions are not enforced yet
+- constructor logic only builds from station-local inventory
+  - it does not yet fetch module materials from other stations or ships
+- station installed modules and active construction are not yet exposed in the viewer contract
+- some viewer follow-camera code is currently broken by a pre-existing missing `followedShipId` property
 - piracy and faction growth are still functional rather than strategically deep
 - no persistence for saves, seeds, or reconnect state
 
@@ -205,26 +229,31 @@ The runtime model still follows the intended layered control architecture:
 - [apps/backend/Simulation/SimulationEngine.cs](/home/jbourdon/repos/space-game/apps/backend/Simulation/SimulationEngine.cs)
   - simulation advancement
   - snapshot / delta composition for galaxy-space systems and local-space entities
-  - inventory, fuel, and energy processing
-  - auto-miner undock state transition fix
+  - inventory, gas/fuel, and energy processing
+  - station module construction
+  - gas harvesting, refueling, and pad-based docking
+  - action timing for mining, spool-up, docking, and undocking
 - [apps/backend/Simulation/ScenarioLoader.cs](/home/jbourdon/repos/space-game/apps/backend/Simulation/ScenarioLoader.cs)
   - faction bootstrap
   - galaxy generation
   - special systems
   - procedural celestial/resource content
   - normalization of authored placements into system-local space
-  - minimal startup seeding for ships, station, and fuel
+  - minimal startup seeding for ships, station, fuel, and module materials
 - [apps/backend/Contracts/WorldContracts.cs](/home/jbourdon/repos/space-game/apps/backend/Contracts/WorldContracts.cs)
   - snapshot and delta contract shape
+  - station dock-pad count
 - [apps/backend/Simulation/RuntimeModels.cs](/home/jbourdon/repos/space-game/apps/backend/Simulation/RuntimeModels.cs)
   - runtime vector math and world model
   - per-item inventories on ships and stations
+  - per-station installed modules and docking pad assignments
 - [apps/viewer/src/GameViewer.ts](/home/jbourdon/repos/space-game/apps/viewer/src/GameViewer.ts)
   - camera, selection, streaming integration, and presentation
   - layered local/remote system presentation
   - orbital reconstruction and moon rendering
   - projected shell markers and hover labels
   - ship card list and multi-window history debugging UI
+  - station HUD docked/pad count readout
 - [apps/viewer/src/style.css](/home/jbourdon/repos/space-game/apps/viewer/src/style.css)
   - HUD layout
   - ship-card rail
@@ -235,14 +264,19 @@ The runtime model still follows the intended layered control architecture:
   - viewer-side snapshot contract for galaxy-space systems and local-space entities
 - [shared/data](/home/jbourdon/repos/space-game/shared/data)
   - scenario and world data definitions
+  - `module-recipes.json` now defines timed module construction costs
 
 ## Validation
 
 Validation passing at the end of this session:
 
 - `dotnet build apps/backend/SpaceGame.Simulation.Api.csproj`
+
+Validation currently failing / blocked:
+
 - `cd apps/viewer && npm run build`
+  - fails because `apps/viewer/src/GameViewer.ts` references a missing `followedShipId` property
 
 ## Last Commit
 
-- `1747d84`
+- `ef62577`