Claude/youthful archimedes x00amm

docs/coop-interaction-ownership.md

@@ -42,6 +42,7 @@ The partner never triggers or advances these.
 | Stage death and checkpoint | `death_hook` (`$00:9D9E`, `$00:9AC7`, `$81:8A5C..8B0B`) | A death with a living partner runs the native death pose, but the partner keeps playing (`solo_death`). A whole-team death resets to P1 at the checkpoint. | No change expected. |
 | E-tank elevator carry | `lift_rtl_hook`, `MmxCoopLiftCarry` | The handler carries the projected body; co-op carries the partner by the same distance. | Both ride; not ownership. |
 | Sprite priority (`.11` bits 4-5) | `MmxCoopSyncPriority` (frame end) | Stage sections write the priority to the world actor once (Storm Eagle's ship sets priority 3). The living partner copies the world actor's bits every frame. | No change expected. |
+| Partner "in play" bit (`.27` bit 7) | `MmxCoopSyncPriority` (frame end) | Spawns store HP\|`$80` and death stores `$80`; the world actor's arrival clears the bit, but a placed partner kept it permanently. Launch Octopus's current generator (`$28`) ignores bodies with it set. A living partner in play now has it cleared each frame. | Both seats. |
 | Ground-shock stun (action `$36`, Flame Mammoth's stomp) | `MmxCoopSyncPriority` (frame end) | The boss tests only the projected world actor. When the world actor enters `$36`, a grounded, living partner enters it the same frame. | Both seats. |
 
 ## 2. Both players, through a partner retry

src/mmx_coop.c

@@ -1142,6 +1142,13 @@ void MmxCoopSyncPriority(uint8_t *r) {
      * Left 0, X's wrapped to 255 and kept him stunned ~288 frames. */
     body[2]=0x36;body[3]=0;body[0x85]=world[0x85];
   }
+  /* .27 bit 7 marks a body not yet (or no longer) in play: spawns store
+   * HP|$80 and death stores $80. The world actor's arrival clears it, but a
+   * placed partner kept it for good. Contact damage ignores it; Launch
+   * Octopus's current generator ($28) does not, so it never lifted him. */
+  if((body[0x27]&128) && (body[0x27]&127) && !(world[0x27]&128) && action!=0x0c &&
+      !MmxCoopTransitionActive())
+    body[0x27]&=127;
 }
 static void eagle_lift_hook(CpuState *cpu,uint32_t pc) {
   if(!enabled || !state.initialized || state.menu_owner || state.scene_owner) return;