Initial Combat Implementation

CLAUDE.md

@@ -41,6 +41,15 @@ Root namespace: **`ProjectM`**. Code lives under `Assets/_Project/Scripts/` in f
 - `IInputComponentData` requires implementing **`FixedString512Bytes ToFixedString()`**.
 - An input-gather system that reads the managed Input System belongs in `GhostInputSystemGroup` as a **non-Burst `ISystem`** (or `SystemBase`), never inside the prediction loop.
 
+### Build gotchas (learned — M2 combat, 2026-05-31)
+
+- **The generated Input Actions C# wrapper must live inside an asmdef** any system needs to reference. By default it generates next to the `.inputactions` (e.g. `Assets/Settings/`), which has no asmdef → it compiles into `Assembly-CSharp`, and asmdef assemblies (`ProjectM.Client`) **cannot** reference that. Fix: set the importer's `wrapperCodePath` (in the `.inputactions.meta`) to a path inside the consuming asmdef, e.g. `Assets/_Project/Scripts/Client/Input/ProjectMInput.cs`, and delete the old generated file. Read the action map via a managed `SystemBase` holding the wrapper; gather `Fire` as a netcode **`InputEvent`** (reset the field each frame, `.Set()` on the press edge — netcode latches the absolute `Count` into the command buffer; the live component value is only the per-tick delta).
+- **Predicted-spawn classification cannot be `[BurstCompile]`d (Netcode 1.13.2).** The cross-assembly generic `Unity.NetCode.LowLevel.SnapshotDataBufferComponentLookup.TryGetComponentDataFromSnapshotHistory<T>()` trips a Burst **internal compiler error** (type-hash resolution). Make the classifier a plain non-Burst `ISystem` (it only runs when spawns are received — cold path). In 1.13.2 that method takes **`ref DynamicBuffer<SnapshotDataBuffer>`** (the public HelloNetcode sample's by-value `data` is from an older version).
+- **A Burst *internal compiler error* corrupts the editor's Burst incremental cache.** After the error is fixed in code, newly-added `[BurstCompile]` entry points (systems **and** generated ghost-component serializers) keep logging `"... is not a known Burst entry point"` and run managed-fallback (slow → server tick-batching, ~30–40s play-enter). A clean compile + green tests + working runtime confirm the code is fine. Clear it with an **editor restart** (or delete `Library/BurstCache` while closed) — a domain reload alone does not.
+- **Projectile/area hit tests must be swept, not point checks.** A point distance check tunnels straight through a target when the per-tick step exceeds the target radius — at high projectile speed *or* whenever the server tick-batches under load. Test the segment the projectile traversed this tick (`[curPos - dir*speed*dt, curPos]`) against each target; order the damage system `[UpdateAfter(MoveSystem)]`. (Caught at runtime, not by a point-based unit test — cover hit detection with a tunnelling regression test.)
+- **In-editor input injection needs a focused Game view — unless you change two settings.** By default the Input System ignores injected/real device input while the Game view is unfocused, so headless (MCP `execute_code`) keypress simulation won't drive `IInputComponentData`. Fix (both now set in this project): `InputSettings.editorInputBehaviorInPlayMode = AllDeviceInputAlwaysGoesToGameView` + `Application.runInBackground = true`. For deterministic, device-independent validation prefer the editor-only **`DebugInputInjectionSystem`** (`ProjectM.Client`, `#if UNITY_EDITOR`): poke its statics from `execute_code` — `DebugInputInjectionSystem.Fire()` / `.SetMove(x,z)` / `.SetAim(x,z)` / `.Stop()` — to drive the local player's `PlayerInput` through the authentic command→prediction pipeline. (Validated: `SetMove` drives + replicates movement. One-shot `Fire` propagation needs a healthy editor — tick-batching under a degraded/corrupt-Burst editor drops one-shot `InputEvent`s while continuous values survive.)
+- **Prototype presentation glue lives in `ProjectM.Client` as MonoBehaviours.** `PrototypeCameraRig` (on the Main Camera) is a tunable player-following ARPG cam (default mid 3/4 ~45° perspective) that reads the local player ghost's `LocalTransform` each LateUpdate. Bright prototype URP-Lit materials are in `Assets/_Project/Materials/` (player cyan, dummy red, projectile yellow, ground grey). `ProjectM.Client` now references `Unity.Transforms` directly (the rig reads `LocalTransform`).
+
 ## Bootstrap & worlds
 
 - `ProjectM.Simulation.GameBootstrap : ClientServerBootstrap` → overrides `Initialize`, sets `AutoConnectPort = 7979` (in-editor auto-connect over IPC; set in M1 — was 0), calls `CreateDefaultClientServerWorlds()`. Entering Play Mode creates separate `ServerWorld` (`WorldFlags.GameServer`) and `ClientWorld` (`WorldFlags.GameClient`) — verified.