Add grenade trajectory, RPG armour priority, empty chargers, mega gravity gun

- Projectiles gets a "Grenade trajectory" toggle. While a frag grenade is
  held, simulate the weapon_frag throw (1200 u/s forward + 120 z, player
  velocity, gravity 600) and trace each step with a new
  trace_solid_segment(); reflect on impact, stop on a slow upward-normal hit,
  and draw the path, landing cross and a 300-unit blast ring. Verified on :99
  (arcs, bounces off the tunnel wall, lands).
- With the RPG equipped, armoured NPCs (striders, gunships, dropships,
  hunter-choppers) sort before normal enemies during target acquisition.
  Added helicopter/chopper to the ARMORED model list.
- Empty health/suit chargers are hidden: read m_iJuice from the server
  datamap (0 = depleted, -1 = unreadable/fail open).
- The citadel supercharged gravity gun (d3_citadel_03, d3_citadel_04,
  d3_breen_01 via IVEngineClient::GetLevelName) is treated as a normal
  weapon, so the melee aimbot no longer restricts it to VULNERABLE NPCs.

7 files changed, 232 insertions, 17 deletions

diff --git a/CONTEXT.md b/CONTEXT.md
index 1e860bf..889c3ab 100644
--- a/CONTEXT.md
+++ b/CONTEXT.md
@@ -201,9 +201,10 @@ vocabulary / decisions.
 
 - Every NPC is classified for ESP and target selection:
   - `IMMUNE` — server `m_takedamage` is `DAMAGE_NO`/`DAMAGE_EVENTS_ONLY`.
-  - `ARMORED` — gunship, strider, dropship: their `OnTakeDamage` only accepts
-    blast damage (`DMG_BLAST`, with a damage threshold on gunships and a
-    distance check on striders). Only the RPG passes; bullets/grenades do not.
+  - `ARMORED` — gunship, strider, dropship, hunter-chopper: their
+    `OnTakeDamage` only accepts blast damage (`DMG_BLAST`, with a damage
+    threshold on gunships and a distance check on striders). Only the RPG
+    passes; bullets/grenades do not.
   - `VULNERABLE` — headcrab, antlion, manhack: punting them with the gravity
     gun / physics impact damage kills them.
   - `NORMAL` — everything else.
@@ -213,7 +214,10 @@ vocabulary / decisions.
   created at glyph size 10 alongside the 16 px body font (`g_font_small`).
 - Aimbot/silent aim/triggerbot/melee skip `IMMUNE` targets always and
   `ARMORED` targets unless the active weapon is the RPG
-  (`active_weapon_contains` for `rocket_launcher`/`rpg`).
+  (`active_weapon_contains` for `rocket_launcher`/`rpg`). With the RPG
+  equipped, armoured candidates are sorted before normal enemies (a
+  `fov - 1000` rank key), so a strider/gunship is acquired even when a normal
+  NPC is closer to the crosshair.
 - Server `m_takedamage` is a `char` in the 2013 SDK
   (`CNetworkVarForDerived(char, m_takedamage)`, `FIELD_CHARACTER`), so it is
   resolved with that type (int fallback) and read as a byte. `0/1` means no
@@ -402,7 +406,11 @@ vocabulary / decisions.
   `IN_ATTACK`: the primary attack launches a held object along
   `EyeVectors()`. No aim-punch compensation is applied there (EyeVectors does
   not add punch); the crowbar path keeps it. Without a held object the primary
-  is a short physics punch.
+  is a short physics punch. The citadel supercharges the gravity gun
+  (`d3_citadel_03`, `d3_citadel_04`, `d3_breen_01`; detected through
+  `IVEngineClient::GetLevelName`, slot 51), and there it is treated as a
+  normal weapon: the `VULNERABLE`-only filter is dropped, so any damageable
+  hostile NPC is selected.
 - Map transitions often switch the active weapon away from the crowbar. The
   state change is logged as `melee: active ... crowbar=0/1` (normal log), and
   a one-time toast says to equip the crowbar. If the client weapon model is
@@ -694,7 +702,10 @@ vocabulary / decisions.
   Reading at the raw offset shifted every count by one type (e.g. RPG read the
   buckshot count 30 against a max of 3, permanently hiding rockets).
 - Chargers and ammo/supply crates are dispensers and are exempt from the
-  fullness filter.
+  fullness filter. Empty health/suit chargers are still hidden: both
+  `CWallHealth` and `CNewRecharge` expose `m_iJuice` (server datamap
+  `FIELD_INTEGER`, resolved at offset 0x47c in this build), and a value of 0
+  removes the charger tag until it recharges. `-1` (unreadable) fails open.
 - Scans the client entity list every 100 ms and tags health, ammo, armor/suit,
   world weapon pickups, the two supply-crate models and generic items.
 - Each tag is a colored marker with a name and optional distance, filtered by
@@ -733,7 +744,17 @@ vocabulary / decisions.
   is a 24-segment horizontal circle projected at the projectile height, with
   every segment near-plane/screen clipped independently, so it still draws
   when the grenade itself is off-screen or behind the camera.
-  Toggles: Fuse timer, Blast radius.
+  Toggles: Fuse timer, Blast radius, Grenade trajectory
+  (`[projectiles] trajectory=1`).
+- Grenade trajectory: while the frag weapon is active, simulate the throw
+  from `weapon_frag.cpp` (eye + forward*18 + right*8, player velocity +
+  (forward + 0.1 z)*1200), gravity 600, dt 0.02, restitution 0.35, friction
+  0.35. Each step traces with `trace_solid_segment` (EngineTraceClient003 slot
+  4, `MASK_PLAYERSOLID`, local player ignored); hits reflect about the impact
+  normal, and an upward normal with a slow vertical speed marks the landing.
+  The polyline, landing cross and a 300-unit blast-radius ring at the landing
+  are drawn with the same near-plane-clipped projector as the radius ring.
+  Verified on `:99` (the line arcs, bounces off a tunnel wall and lands).
 
 ## Roadmap / TODO
 
diff --git a/src/esp.cpp b/src/esp.cpp
index d32a8bc..594a8fa 100644
--- a/src/esp.cpp
+++ b/src/esp.cpp
@@ -320,7 +320,8 @@ static int npc_damage_class(int idx, const char *model) {
   if (td == 0 || td == 1) // DAMAGE_NO / DAMAGE_EVENTS_ONLY
     return NPC_DMG_IMMUNE;
   if (model_has(model, "gunship") || model_has(model, "combine_strider") ||
-      model_has(model, "dropship"))
+      model_has(model, "dropship") || model_has(model, "helicopter") ||
+      model_has(model, "chopper"))
     return NPC_DMG_ARMORED;
   if (model_has(model, "headcrab") || model_has(model, "antlion") ||
       model_has(model, "manhack"))
@@ -822,6 +823,12 @@ static bool select_aim_target(const QAngle &view, unsigned bone_mask,
       *(int *)((uintptr_t)local_ent + g_net.health) <= 0)
     return false;
 
+  // With the RPG equipped, armoured units (striders, gunships, dropships,
+  // hunter-choppers) are the ones ordinary shots cannot hurt, so prefer them
+  // over normal NPCs when acquiring.
+  bool rpg = active_weapon_contains(local_ent, "rocket_launcher") ||
+             active_weapon_contains(local_ent, "rpg");
+
   auto try_target = [&](int idx, bool enforce_fov, Vector &pt,
                         float &fov) -> bool {
     if (idx <= 0 || idx == local)
@@ -899,6 +906,8 @@ static bool select_aim_target(const QAngle &view, unsigned bone_mask,
     int idx;
     float fov;
     Vector approx;
+    bool armored;
+    float key;
   };
   Candidate cands[16];
   int ncands = 0;
@@ -928,6 +937,7 @@ static bool select_aim_target(const QAngle &view, unsigned bone_mask,
       continue;
     if (!npc_can_be_damaged(idx, model))
       continue;
+    bool armored = npc_damage_class(idx, model) == NPC_DMG_ARMORED;
 
     float maxz = g_net.maxs >= 0 ? *(float *)(e + g_net.maxs + 8) : 72.0f;
     if (!(maxz > 4.0f && maxz < 512.0f))
@@ -940,16 +950,17 @@ static bool select_aim_target(const QAngle &view, unsigned bone_mask,
     float fov = getfov(view, angle_to(g_cam_eye, approx));
     if (fov > max_fov)
       continue;
+    float key = (rpg && armored) ? fov - 1000.0f : fov;
 
     int pos = ncands;
-    while (pos > 0 && cands[pos - 1].fov > fov)
+    while (pos > 0 && cands[pos - 1].key > key)
       pos--;
     if (ncands < 16)
       ncands++;
     for (int j = ncands - 1; j > pos; j--)
       cands[j] = cands[j - 1];
     if (pos < 16)
-      cands[pos] = {idx, fov, approx};
+      cands[pos] = {idx, fov, approx, armored, key};
   }
 
   if (ncands == 0) {
@@ -1309,6 +1320,26 @@ bool gravity_gun_active(void *local_ent) {
          (model && strcasestr(model, "physcannon"));
 }
 
+// The citadel supercharges the gravity gun (d3_citadel_03 onward). It can then
+// punt any NPC, so the melee aimbot should not restrict itself to
+// physics-vulnerable units.
+static bool supercharged_gravity_gun() {
+  if (!g_iface.engine)
+    return false;
+  using Fn = const char *(*)(void *);
+  const char *m = vfunc<Fn>(g_iface.engine, 51)(g_iface.engine);
+  if (!m)
+    return false;
+  bool supe = strstr(m, "d3_citadel_03") || strstr(m, "d3_citadel_04") ||
+              strstr(m, "d3_breen_01");
+  static const char *logged_map = nullptr;
+  if (logged_map != m) {
+    logged_map = m;
+    logf("melee: gravity gun map=%s supercharged=%d", m, (int)supe);
+  }
+  return supe;
+}
+
 bool melee_aimbot_apply(CUserCmd *cmd, bool gravity) {
   if (!g_iface.entitylist || g_net.origin < 0)
     return false;
@@ -1324,6 +1355,7 @@ bool melee_aimbot_apply(CUserCmd *cmd, bool gravity) {
 
   // The punted object can travel much farther than the crowbar.
   float max_range = gravity ? 1200.0f : MELEE_RANGE;
+  bool supercharged = gravity && supercharged_gravity_gun();
 
   using Fn = int (*)(void *);
   int hi = vfunc<Fn>(g_iface.entitylist, 6)(g_iface.entitylist);
@@ -1363,8 +1395,10 @@ bool melee_aimbot_apply(CUserCmd *cmd, bool gravity) {
       continue;
     if (!npc_can_be_damaged(idx, model))
       continue;
-    // The gravity gun is only the tool for physics-vulnerable units.
-    if (gravity && npc_damage_class(idx, model) != NPC_DMG_VULNERABLE)
+    // The normal gravity gun is only the tool for physics-vulnerable units;
+    // the citadel version behaves like a normal weapon.
+    if (gravity && !supercharged &&
+        npc_damage_class(idx, model) != NPC_DMG_VULNERABLE)
       continue;
 
     Vector origin{*(float *)(e + g_net.origin),
@@ -2747,6 +2781,11 @@ static void items_collect(int local_idx) {
     int kind = classify_item(model, cls, label, sizeof(label));
     if (kind < 0)
       continue;
+    // Health/suit chargers are dispensers that stay useful after a refill, but
+    // an empty one cannot give anything. m_iJuice is 0 when depleted (until it
+    // recharges); only hide the tag once the server value is readable.
+    if (strcasestr(label, "charger") && server_item_juice(idx) == 0)
+      continue;
 
     Vector origin{*(float *)((uintptr_t)ent + g_net.origin),
                   *(float *)((uintptr_t)ent + g_net.origin + 4),
@@ -3045,6 +3084,114 @@ static void projs_collect(int local_idx) {
   }
 }
 
+// Frag-grenade path preview: throw velocity from weapon_frag.cpp (eye/right
+// offset, forward*1200 + 0.1 z), gravity 600, and a simple bounce model.
+// Shows the bounces and the first landing with the blast-radius ring.
+static void draw_grenade_trajectory(int local_idx) {
+  if (!g_proj_traj || !g_iface.entitylist)
+    return;
+  void *le = entitylist_get(local_idx);
+  if (!le)
+    return;
+  if (!active_weapon_contains(le, "frag") &&
+      !active_weapon_contains(le, "w_grenade"))
+    return;
+
+  QAngle va = engine_view_angles();
+  float pitch = va.x * PI_F / 180.0f;
+  float yaw = va.y * PI_F / 180.0f;
+  float cp = cosf(pitch), sp = sinf(pitch);
+  float cy = cosf(yaw), sy = sinf(yaw);
+  Vector fwd{cp * cy, cp * sy, -sp};
+  Vector right{sy, -cy, 0.0f};
+
+  Vector src{g_cam_eye.x + fwd.x * 18.0f + right.x * 8.0f,
+             g_cam_eye.y + fwd.y * 18.0f + right.y * 8.0f,
+             g_cam_eye.z + fwd.z * 18.0f};
+  Vector vel{};
+  if (g_net.velocity >= 0) {
+    const float *pv = (const float *)((uintptr_t)le + g_net.velocity);
+    vel = Vector{pv[0], pv[1], pv[2]};
+  }
+  vel.x += fwd.x * 1200.0f;
+  vel.y += fwd.y * 1200.0f;
+  vel.z += fwd.z * 1200.0f + 120.0f; // vForward[2] += 0.1
+
+  const float gravity = 600.0f;
+  const float dt = 0.02f;
+  const float restitution = 0.35f;
+  const float friction = 0.35f;
+
+  Vector pts[128];
+  int n = 0;
+  Vector pos = src;
+  pts[n++] = pos;
+  bool landed = false;
+  for (int step = 0; step < 240 && n < 127; step++) {
+    Vector nv = vel;
+    nv.z -= gravity * dt;
+    Vector next{pos.x + nv.x * dt, pos.y + nv.y * dt, pos.z + nv.z * dt};
+    Vector hit_end{}, normal{};
+    if (trace_solid_segment(pos, next, le, hit_end, normal)) {
+      pts[n++] = hit_end;
+      float vn = vel.x * normal.x + vel.y * normal.y + vel.z * normal.z;
+      Vector vt{vel.x - vn * normal.x, vel.y - vn * normal.y,
+                vel.z - vn * normal.z};
+      float keep = 1.0f - friction;
+      vel.x = vt.x * keep - normal.x * vn * restitution;
+      vel.y = vt.y * keep - normal.y * vn * restitution;
+      vel.z = vt.z * keep - normal.z * vn * restitution;
+      float vlen2 = vel.x * vel.x + vel.y * vel.y + vel.z * vel.z;
+      pos.x = hit_end.x + normal.x * 1.0f;
+      pos.y = hit_end.y + normal.y * 1.0f;
+      pos.z = hit_end.z + normal.z * 1.0f;
+      if (normal.z > 0.6f && (vn > -80.0f || vlen2 < 2500.0f)) {
+        landed = true;
+        break;
+      }
+    } else {
+      pos = next;
+      vel = nv;
+      pts[n++] = pos;
+    }
+  }
+
+  surf_color(255, 210, 90, 200);
+  for (int i = 0; i + 1 < n; i++) {
+    int x0, y0, x1, y1;
+    if (project_segment(pts[i], pts[i + 1], x0, y0, x1, y1))
+      surf_line(x0, y0, x1, y1);
+  }
+
+  Vector land = landed ? pos : pts[n - 1];
+  float ssx, ssy;
+  if (world_to_screen(land, ssx, ssy)) {
+    int x = (int)ssx, y = (int)ssy;
+    surf_color(255, 210, 90, 230);
+    surf_rect(0, x - 3, y - 3, x + 3, y + 3);
+    surf_line(x - 9, y, x - 4, y);
+    surf_line(x + 4, y, x + 9, y);
+    surf_line(x, y - 9, x, y - 4);
+    surf_line(x, y + 4, x, y + 9);
+  }
+  if (landed) {
+    const int SEG = 24;
+    const float radius = 300.0f; // CBaseGrenade m_DmgRadius
+    surf_color(255, 120, 40, 120);
+    for (int k = 0; k < SEG; k++) {
+      float a0 = (float)k * 2.0f * PI_F / (float)SEG;
+      float a1 = (float)(k + 1) * 2.0f * PI_F / (float)SEG;
+      Vector p0{land.x + cosf(a0) * radius, land.y + sinf(a0) * radius,
+                land.z + 1.0f};
+      Vector p1{land.x + cosf(a1) * radius, land.y + sinf(a1) * radius,
+                land.z + 1.0f};
+      int x0, y0, x1, y1;
+      if (project_segment(p0, p1, x0, y0, x1, y1))
+        surf_line(x0, y0, x1, y1);
+    }
+  }
+}
+
 void esp_draw_projectiles() {
   if (!g_surface || !g_iface.entitylist || g_net.origin < 0)
     return;
@@ -3055,6 +3202,7 @@ void esp_draw_projectiles() {
       return;
   }
   projs_collect(engine_get_local_player());
+  draw_grenade_trajectory(engine_get_local_player());
   for (int i = 0; i < g_nprojs; i++) {
     const ProjTarget &p = g_projs[i];
     int r = 255, g = 170, b = 60;
diff --git a/src/gui.cpp b/src/gui.cpp
index fe82762..454e2cb 100644
--- a/src/gui.cpp
+++ b/src/gui.cpp
@@ -454,6 +454,9 @@ static void build_cards() {
              &g_proj_fuse);
   add_toggle(proj, "Blast radius",
              "Draw the projectile's damage radius on the ground.", &g_proj_radius);
+  add_toggle(proj, "Grenade trajectory",
+             "Predict the frag grenade path, bounces and landing point.",
+             &g_proj_traj);
 
   int chams = add_card(2, &g_chams, "Chams",
                        "Per-relationship model colours.", true);
diff --git a/src/hl2h.h b/src/hl2h.h
index 34bf04f..32cee8f 100644
--- a/src/hl2h.h
+++ b/src/hl2h.h
@@ -230,7 +230,7 @@ struct FeatureState {
 extern FeatureState g_bhop, g_abh, g_jumpbug, g_melee, g_spread, g_esp,
     g_aimbot, g_triggerbot, g_silentaim, g_item_esp, g_fullbright,
     g_world_tint, g_fog, g_skybox, g_projectiles, g_chams;
-extern bool g_proj_fuse, g_proj_radius;
+extern bool g_proj_fuse, g_proj_radius, g_proj_traj;
 
 // Chams settings per relationship, and separate visible / through-wall
 // (invisible) material and colour. The viewmodel has a single style.
@@ -319,6 +319,7 @@ int server_player_ammo(int idx, int type);
 uint32_t server_player_weapon(int idx, int slot);
 float server_grenade_detonate(int idx);
 float server_grenade_radius(int idx);
+int server_item_juice(int idx);
 int server_entity_count();
 void *server_entity_base(int idx);
 const char *server_entity_classname(int idx);
@@ -366,6 +367,8 @@ void set_silent_restore(const QAngle &angles);
 bool is_visible(const Vector &eye, const Vector &point,
                 void *self = nullptr, void *target = nullptr);
 void *trace_entity(const Vector &start, const Vector &end, void *ignore);
+bool trace_solid_segment(const Vector &start, const Vector &end, void *ignore,
+                         Vector &out_end, Vector &out_normal);
 float ground_distance(const Vector &origin, void *ignore, float max_dist);
 bool point_ground(const Vector &point, void *ignore);
 
diff --git a/src/menu.cpp b/src/menu.cpp
index 873f5ed..1064365 100644
--- a/src/menu.cpp
+++ b/src/menu.cpp
@@ -63,6 +63,7 @@ FeatureState g_skybox{false, 0}; // skybox.png image override
 FeatureState g_projectiles{true, 0}; // grenade / rocket ESP
 bool g_proj_fuse = true;
 bool g_proj_radius = true;
+bool g_proj_traj = true;
 FeatureState g_chams{false, 0};
 ChamsGroup g_chams_hostile{true, 3, {255, 60, 60, 255}, true, 3,
                            {255, 60, 60, 255}};
@@ -241,9 +242,10 @@ void config_save() {
           g_fog_start, g_fog_end, (int)g_fog_skybox, (int)g_fog_disable);
   fprintf(f, "[skybox]\nactive=%d\nbind=%d\n", g_skybox.active,
           g_skybox.bind);
-  fprintf(f, "[projectiles]\nactive=%d\nbind=%d\nfuse=%d\nradius=%d\n",
+  fprintf(f, "[projectiles]\nactive=%d\nbind=%d\nfuse=%d\nradius=%d\n"
+             "trajectory=%d\n",
           g_projectiles.active, g_projectiles.bind, (int)g_proj_fuse,
-          (int)g_proj_radius);
+          (int)g_proj_radius, (int)g_proj_traj);
   fprintf(f, "[chams]\nactive=%d\nbind=%d\n", g_chams.active, g_chams.bind);
   auto save_chams = [&](const char *name, const ChamsGroup &g) {
     fprintf(f, "[%s]\nvis=%d\nvis_mat=%d\nvis_r=%d\nvis_g=%d\nvis_b=%d\n"
@@ -425,6 +427,8 @@ static bool config_load() {
           g_proj_fuse = atoi(val) != 0;
         else if (strcmp(key, "radius") == 0)
           g_proj_radius = atoi(val) != 0;
+        else if (strcmp(key, "trajectory") == 0)
+          g_proj_traj = atoi(val) != 0;
       }
       if (chams_grp) {
         ChamsGroup &g = *chams_grp;
@@ -702,6 +706,7 @@ void config_reset_defaults() {
   g_projectiles = {true, 0};
   g_proj_fuse = true;
   g_proj_radius = true;
+  g_proj_traj = true;
   g_chams = {false, 0};
   g_chams_hostile = {true, 3, {255, 60, 60, 255}, true, 3,
                      {255, 60, 60, 255}};
diff --git a/src/server.cpp b/src/server.cpp
index bae355e..6479b25 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -58,6 +58,7 @@ static int g_srv_mapname = -1;
 static int g_srv_armor = -1;
 static int g_srv_detonate = -1;
 static int g_srv_grenade_radius = -1;
+static int g_srv_juice = -1;
 static int g_srv_ammo = -1;
 static int g_srv_myweapons = -1;
 static bool g_srv_ready = false;
@@ -162,6 +163,7 @@ bool resolve_server_netvars() {
   // CBaseGrenade fuse / blast radius (m_flDetonateTime is not networked).
   g_srv_detonate = datamap_offset("m_flDetonateTime", FIELD_TIME);
   g_srv_grenade_radius = datamap_offset("m_DmgRadius", FIELD_FLOAT);
+  g_srv_juice = datamap_offset("m_iJuice", FIELD_INTEGER);
   // CBaseCombatCharacter arrays: ammo counts and the weapon handle list.
   g_srv_ammo = datamap_offset("m_iAmmo", FIELD_INTEGER, 0x40, 0x4000);
   g_srv_myweapons = datamap_offset("m_hMyWeapons", FIELD_EHANDLE);
@@ -171,13 +173,13 @@ bool resolve_server_netvars() {
          "modelindex=%d absvel=%d vel=%d activeweapon=%d relationship=%d "
          "followtarget=%d spawnflags=%d hacked=%d npcstate=%d "
          "takedamage=%d mapname=%d armor=%d detonate=%d dmgradius=%d "
-         "ammo=%d myweapons=%d",
+         "ammo=%d myweapons=%d juice=%d",
          g_server.path.c_str(), g_srv_health, g_srv_maxhealth, g_srv_lifestate,
          g_srv_modelindex, g_srv_absvelocity, g_srv_velocity,
          g_srv_activeweapon, g_srv_relationship, g_srv_followtarget,
          g_srv_spawnflags, g_srv_hacked, g_srv_npcstate, g_srv_takedamage,
          g_srv_mapname, g_srv_armor, g_srv_detonate, g_srv_grenade_radius,
-         g_srv_ammo, g_srv_myweapons);
+         g_srv_ammo, g_srv_myweapons, g_srv_juice);
     fail_logged = false;
   } else if (!fail_logged) {
     fail_logged = true;
@@ -475,6 +477,18 @@ float server_grenade_radius(int idx) {
   return *(float *)((uintptr_t)base + g_srv_grenade_radius);
 }
 
+// CWallHealth / CNewRecharge share the same m_iJuice layout (the fields before
+// it match), so one datamap offset works for both health and suit chargers.
+int server_item_juice(int idx) {
+  if (!g_srv_ready || g_srv_juice < 0)
+    return -1;
+  void *base = nullptr;
+  server_entity_health(idx, nullptr, nullptr, &base);
+  if (!base)
+    return -1;
+  return *(int *)((uintptr_t)base + g_srv_juice);
+}
+
 // Server-side CBaseCombatCharacter::m_iAmmo array (reserve ammo). The datamap
 // offset points at the CNetworkArray length header; the elements start 4 bytes
 // later (confirmed by the shifted current/max table).
diff --git a/src/vischeck.cpp b/src/vischeck.cpp
index c8c0942..6b531b9 100644
--- a/src/vischeck.cpp
+++ b/src/vischeck.cpp
@@ -232,6 +232,27 @@ void *trace_entity(const Vector &start, const Vector &end, void *ignore) {
   return tr.ent;
 }
 
+// First solid/world hit along a segment, for grenade bounce prediction.
+// Returns false on a clear path; otherwise fills the impact point and normal.
+bool trace_solid_segment(const Vector &start, const Vector &end, void *ignore,
+                         Vector &out_end, Vector &out_normal) {
+  if (!g_iface.enginetrace)
+    return false;
+  RayCompat ray;
+  make_ray(ray, start, end);
+  GameTraceCompat tr{};
+  EntityFilter filter(ignore);
+  using TraceRayFn = void (*)(void *, const RayCompat *, unsigned, void *,
+                              GameTraceCompat *);
+  vfunc<TraceRayFn>(g_iface.enginetrace, 4)(g_iface.enginetrace, &ray,
+                                            MASK_PLAYERSOLID, &filter, &tr);
+  if (tr.startsolid || tr.fraction >= 1.0f)
+    return false;
+  out_end = tr.endpos;
+  out_normal = tr.normal;
+  return true;
+}
+
 // True when a downward point trace from just above `point` finds a standable
 // surface. Used by edge jump: a ledge has no floor within the probe, slopes and
 // stairs do.