Added

• Loco Controls window (draggable) with detented sliders for reverser, throttle, dynamic brake, independent brake, service brake, plus an emergency toggle.
• Inspector window (draggable) with tabs: Info / Options / Ops.
• C hotkey to toggle the Loco Controls window (only when a locomotive is selected). Defaults to bottom-left when opened.
• Traction cut-out toggle (separate from brake valve cut-out).
• ui:selectedVehicleChanged event to support UI auto-open behavior when selection changes.

Changed

• MU/DPU control distribution:
  • MU follows only when directly coupled to the lead.
  • DPU follows when fence matches the lead TX fence.
  • Follower units default to brake-valve cut-out without overriding explicit user changes.
• Coupling distance threshold relaxed to make manual coupling more forgiving.
• Left HUD layout now re-lays out each frame to avoid overlapping the menu area.

Fixed

• Restored air simulation updates by calling stepAirPropagation() each tick (required for BP/BC behavior and gauges).
• BP/BC analog gauge now updates correctly (air state was not advancing).
• Inspector tab content now renders reliably after moving the window (mask is world-space and follows the window).
• Inspector content masking no longer shows as a visible “white panel”.
• Controls window sliders no longer jump min↔max (pointer coordinates now respect window position).
• Low-speed HUD speed readout now uses a small deadband to prevent flicker around ~0 km/h.
• Overlay toggle reliability improved by capturing key input for 1..9 plus I/H.
• Removed duplicate UI key usage; overlays remapped to 1..9 / Ctrl+1..9.
• Controls popup now reflects live loco state even when changed via keyboard.
• Analog instrument toggle (I) is now robust (fallback raw key listener).
• Ops physics runtime errors in stepOpsSimulation:
  • Reintroduced per-tick working maps (pos/vel/heading/forces) and stable chain ordering via getLinearVehicleOrder.
  • Fixed traction and braking force application to use local forward vectors (hx/hy).

UI Notes

• Removed the redundant compact speed HUD line (analog instruments + engine HUD remain).
• Inspector styling unified with other windows (title bar + accent strip + draggable behavior).
• Inspector options clarified:
  • Removed ambiguous “Air cutout” for cars.
  • Renamed to “Brake valve cut-out” for locomotives.

Added

• Performance HUD toggle (F2) with rolling averages (world/ops/render) plus object counts.
• Coupler debug overlay (F3) showing candidate coupler line + metrics (distance, relative speed, facing).

Fixed

• Resolved duplicate UI setter methods in WorldScene (kept preferred behavior; removed duplicates to avoid Vite warnings).
• Added safe coupling debug capture in tryAutoCoupleKnuckles() and a world-space overlay (F3).

Docs

• Added docs/CONTROLS.md and updated the changelog.

UI

• Analog HUD toggle (I) now works reliably by forwarding the keypress from WorldScene → UIScene.
• Inspector standardized to tabs: Info / Options / Ops (driving controls live only in the Controls window).
• Left HUD switched to a compact one-line readout (removed redundant full stats box).

Air / Simulation

• Added explicit erPsi on the lead loco (derived from service handle) so the MR/ER gauge reflects commands.
• MR drawdown now accounts for both BP and AR charging across the whole train (more noticeable MR dip/recovery).

Performance

• Train rendering now builds a per-frame vehicle lookup map to avoid repeated O(n) .find() calls (helps large consists).

High-impact priorities

1. Coupling + air-line behavior
   • Auto knuckle coupling when pushed together with realistic compression and within coupling distance.
   • Auto air connect when knuckles couple; auto air disconnect when knuckles open/break.
   • Manual uncouple/open should prevent immediate re-couple for a brief cooldown.
2. Logic pass (realism before gamey, except air-flow)
   • Audit MU/DPU authority edges and keep follower behavior (cut-outs, brake handling) predictable.
   • Re-check air propagation direction with flipped consists and mid-consist power.
   • Sanity-check resistance/tractive-effort tuning against SD40-2 targets.
3. Performance pass (100+ vehicles)
   • Measure and reduce per-frame allocations in WorldScene + TrainRender.
   • Reduce Graphics redraw cost (more sprite/RtT reuse, fewer geometry rebuilds).
   • Add simple view-culling and update throttling for off-screen vehicles.
4. UI coherence pass
   • One window theme (title bar accent, drag, close, padding).
   • Input validation + hit areas for all controls.
   • Fix overlap/anchoring on common resolutions.

Backlog / Ideas

• Add HUD text for the current track speed limit (and, if feasible, the next segment’s speed limit if it differs).
• Add a build script to update an in-game popup window from docs/CHANGELOG.md.
• Route planning UI (Inspector Ops tab).
• Better car art / silhouettes.
• Render-to-texture caching experiments.
• More robust coupling UX (auto-snap + clear feedback).
• Keybind editor / rebinding UI improvements.

Documentation note

• Keep docs/CONTROLS.md authoritative for key bindings.