# Phase C+7-only diff (synthesized from working tree minus cumulative C+5/C+6/C+6½/XAM changes)
#
# Full uncommitted diff is in `fix.diff` (1431 lines, includes all
# pre-existing Phase C work since HEAD).
#
# This file isolates the ~30 LOC body changes + ~160 LOC test additions
# that constitute Phase C+7.

--- a/crates/xenia-kernel/src/exports.rs (C+6½ baseline)
+++ b/crates/xenia-kernel/src/exports.rs (C+7)

# Body 1: ke_set_event — match canary's constant-1 return (xevent.cc:60-64)

-fn ke_set_event(ctx: &mut PpcContext, mem: &GuestMemory, state: &mut KernelState) {
-    let h = ctx.gpr[3] as u32;
-    ensure_dispatcher_object(state, mem, h);
-    let previous = match state.objects.get_mut(&h) {
-        Some(KernelObject::Event { signaled, .. }) => {
-            let prev = *signaled;
-            *signaled = true;
-            prev as u32
-        }
-        _ => 0,
-    };
-    state.audit_signal(h, ctx.lr as u32, "KeSetEvent", previous as u64);
-    wake_eligible_waiters(state, h);
-    ctx.gpr[3] = previous as u64;
-}
+fn ke_set_event(ctx: &mut PpcContext, mem: &GuestMemory, state: &mut KernelState) {
+    let h = ctx.gpr[3] as u32;
+    ensure_dispatcher_object(state, mem, h);
+    // Canary parity (xevent.cc:60-64): `XEvent::Set` returns constant `1`
+    // on success, NOT the prior signaled state as the NT contract claims.
+    // We compute `previous` for internal bookkeeping (audit_signal,
+    // wake_eligible_waiters honor the prior-state read), but report
+    // `1` for success / `0` for "no dispatcher found" to match the
+    // canary Phase A oracle. See Phase C+7 investigation.md.
+    let (previous, found) = match state.objects.get_mut(&h) {
+        Some(KernelObject::Event { signaled, .. }) => {
+            let prev = *signaled;
+            *signaled = true;
+            (prev as u32, true)
+        }
+        _ => (0u32, false),
+    };
+    state.audit_signal(h, ctx.lr as u32, "KeSetEvent", previous as u64);
+    wake_eligible_waiters(state, h);
+    ctx.gpr[3] = if found { 1 } else { 0 };
+}

# Body 2: nt_set_event — out-pointer writes constant 1 not prior state
# (xboxkrnl_threading.cc:610-628 + xevent.cc:60-64 chain)

-fn nt_set_event(ctx: &mut PpcContext, mem: &GuestMemory, state: &mut KernelState) {
-    let handle = ctx.gpr[3] as u32;
-    let prev_ptr = ctx.gpr[4] as u32;
-    let previous = match state.objects.get_mut(&handle) {
-        Some(KernelObject::Event { signaled, .. }) => {
-            let prev = *signaled;
-            *signaled = true;
-            prev as u32
-        }
-        _ => 0,
-    };
-    state.audit_signal(handle, ctx.lr as u32, "NtSetEvent", previous as u64);
-    wake_eligible_waiters(state, handle);
-    if prev_ptr != 0 {
-        mem.write_u32(prev_ptr, previous);
-    }
-    ctx.gpr[3] = STATUS_SUCCESS;
-}
+fn nt_set_event(ctx: &mut PpcContext, mem: &GuestMemory, state: &mut KernelState) {
+    let handle = ctx.gpr[3] as u32;
+    let prev_ptr = ctx.gpr[4] as u32;
+    // Canary parity (xboxkrnl_threading.cc:610-628): the optional out-pointer
+    // is filled with `was_signalled` = `ev->Set()` = constant 1 (see
+    // xevent.cc:60-64), NOT the prior signaled state. r3 carries
+    // STATUS_SUCCESS. We retain `previous` for internal audit/wake plumbing.
+    let (previous, found) = match state.objects.get_mut(&handle) {
+        Some(KernelObject::Event { signaled, .. }) => {
+            let prev = *signaled;
+            *signaled = true;
+            (prev as u32, true)
+        }
+        _ => (0u32, false),
+    };
+    state.audit_signal(handle, ctx.lr as u32, "NtSetEvent", previous as u64);
+    wake_eligible_waiters(state, handle);
+    if prev_ptr != 0 && found {
+        mem.write_u32(prev_ptr, 1);
+    }
+    ctx.gpr[3] = STATUS_SUCCESS;
+}

# Test additions (in tests module): 6 new unit tests; see file lines 7179-7340
# - ke_set_event_returns_constant_one_on_unsignaled_auto_reset
# - ke_set_event_returns_constant_one_on_already_signaled_manual_reset
# - nt_set_event_null_prev_ptr_returns_status_success_no_write
# - nt_set_event_valid_prev_ptr_writes_constant_one_and_returns_success
# - nt_set_event_on_signaled_event_writes_one
# - ke_set_event_post_fix_still_wakes_waiter

# LOC summary (Phase C+7 only, additive on C+6½ baseline):
#   body changes:  ~14 net added lines across 2 functions
#   test additions: ~160 lines (6 tests)
#   total:         ~174 LOC, 1 file