diff --git a/fedac/native/ac-os b/fedac/native/ac-os
index 2d9e2e7bd2..a879862d67 100755
--- a/fedac/native/ac-os
+++ b/fedac/native/ac-os
@@ -977,8 +977,10 @@ pull_ota() {
     fi
     log "SHA256 verified: ${ACTUAL_HASH:0:16}..."
 
-    # Override VMLINUZ so flash_usb uses the downloaded kernel
+    # Override VMLINUZ and build name so flash_usb uses the downloaded kernel
+    # (not the locally-generated name from scripts/build-name.sh)
     VMLINUZ="${PULLED_KERNEL}"
+    export AC_BUILD_NAME="${BUILD_NAME}"
     log "Ready to flash: ${BUILD_NAME}"
 }
 
diff --git a/fedac/native/pieces/prompt.mjs b/fedac/native/pieces/prompt.mjs
index 35a03300eb..433d129f01 100644
--- a/fedac/native/pieces/prompt.mjs
+++ b/fedac/native/pieces/prompt.mjs
@@ -333,6 +333,27 @@ function execute(cmd, system) {
     return;
   }
 
+  // Set default boot piece
+  if (baseWord === "boot") {
+    if (spaceIdx > 0) {
+      const pieceName = cmd.slice(spaceIdx + 1).trim();
+      if (pieceName) {
+        system?.saveConfig?.("piece", pieceName);
+        message = "boot → " + pieceName;
+      } else {
+        message = "usage: boot <piece-name>";
+      }
+    } else {
+      // Show current boot piece
+      const raw = system?.readFile?.("/mnt/config.json");
+      let cur = "notepat";
+      if (raw) try { cur = JSON.parse(raw).piece || cur; } catch (_) {}
+      message = "boot piece: " + cur;
+    }
+    messageFrame = 0;
+    return;
+  }
+
   // Dark/light mode override
   if (lower === "dark") {
     __theme._forceDark = true;
diff --git a/fedac/native/src/ac-native.c b/fedac/native/src/ac-native.c
index 89c3e1c662..4661c158f5 100644
--- a/fedac/native/src/ac-native.c
+++ b/fedac/native/src/ac-native.c
@@ -2074,6 +2074,27 @@ int main(int argc, char *argv[]) {
         }
     }
 
+    // Check for previous crash (written by signal handler)
+    {
+        FILE *cf = fopen("/mnt/crash.json", "r");
+        if (cf) {
+            char cbuf[512] = {0};
+            fread(cbuf, 1, sizeof(cbuf) - 1, cf);
+            fclose(cf);
+            char sig[32] = {0};
+            parse_config_string(cbuf, "\"signal\"", sig, sizeof(sig));
+            if (sig[0]) {
+                rt->crash_active = 1;
+                rt->crash_frame = 0;
+                snprintf(rt->crash_msg, sizeof(rt->crash_msg),
+                         "previous crash: %s", sig);
+                ac_log("[ac-native] Previous crash detected: %s\n", sig);
+            }
+            // Remove crash file so we don't re-show it
+            remove("/mnt/crash.json");
+        }
+    }
+
     // Override piece_path from config.json boot piece (pieces bundled at /pieces/)
     // Resolve aliases: "claude" and "cc" → terminal (with param "claude")
     if (strcmp(rt->piece, "claude") == 0 || strcmp(rt->piece, "cc") == 0) {
@@ -2844,9 +2865,13 @@ int main(int argc, char *argv[]) {
                 }
                 JS_FreeValue(rt->ctx, global);
 
-                // Reset counters
+                // Reset counters and crash state
                 rt->paint_count = 0;
                 rt->sim_count = 0;
+                rt->crash_active = 0;
+                rt->crash_count = 0;
+                rt->crash_frame = 0;
+                rt->crash_msg[0] = 0;
 
                 // NOTE: "claude" and "cc" aliases removed — claude.mjs handles auth curtain
                 // before jumping to terminal:claude itself.
@@ -2884,6 +2909,26 @@ int main(int argc, char *argv[]) {
 
             clock_gettime(CLOCK_MONOTONIC, &_pf_paint1);
 
+            // Crash overlay — red bar with error message when JS throws
+            if (rt->crash_active) {
+                rt->crash_frame++;
+                int bar_h = 24;
+                int flash = (rt->crash_frame < 30) ? (rt->crash_frame % 6 < 3 ? 255 : 180) : 200;
+                graph_ink(&graph, (ACColor){flash, 0, 0, 240});
+                graph_box(&graph, 0, 0, screen->width, bar_h, 1);
+                graph_ink(&graph, (ACColor){255, 255, 255, 255});
+                font_draw_matrix(&graph, "CRASH", 4, 4, 2);
+                // Truncate message to fit screen
+                char crash_display[128];
+                snprintf(crash_display, sizeof(crash_display), "%s", rt->crash_msg);
+                graph_ink(&graph, (ACColor){255, 200, 200, 255});
+                font_draw_matrix(&graph, crash_display, 60, 8, 1);
+                // Auto-dismiss after 5 seconds (300 frames at 60fps)
+                if (rt->crash_frame > 300) {
+                    rt->crash_active = 0;
+                }
+            }
+
             // Software cursor on its own overlay buffer (unaffected by KidLisp effects)
             if (cursor_fb && input && (input->pointer_x || input->pointer_y)) {
                 fb_clear(cursor_fb, 0x00000000); // transparent
diff --git a/fedac/native/src/js-bindings.c b/fedac/native/src/js-bindings.c
index b5c49b8f2d..a69c830191 100644
--- a/fedac/native/src/js-bindings.c
+++ b/fedac/native/src/js-bindings.c
@@ -5316,6 +5316,14 @@ void js_call_boot(ACRuntime *rt) {
     }
 }
 
+// Helper: record a JS crash for the overlay
+static void js_record_crash(ACRuntime *rt, const char *fn_name, const char *msg) {
+    rt->crash_active = 1;
+    rt->crash_count++;
+    rt->crash_frame = 0;
+    snprintf(rt->crash_msg, sizeof(rt->crash_msg), "%s(): %s", fn_name, msg ? msg : "unknown");
+}
+
 void js_call_paint(ACRuntime *rt) {
     if (!JS_IsFunction(rt->ctx, rt->paint_fn)) return;
     current_rt = rt;
@@ -5328,6 +5336,7 @@ void js_call_paint(ACRuntime *rt) {
         JSValue stack = JS_GetPropertyStr(rt->ctx, exc, "stack");
         const char *stack_str = JS_ToCString(rt->ctx, stack);
         fprintf(stderr, "[js] paint() error: %s\n%s\n", str, stack_str ? stack_str : "");
+        js_record_crash(rt, "paint", str);
         if (stack_str) JS_FreeCString(rt->ctx, stack_str);
         JS_FreeValue(rt->ctx, stack);
         JS_FreeCString(rt->ctx, str);
@@ -5387,6 +5396,7 @@ void js_call_act(ACRuntime *rt) {
             const char *stack_str = JS_ToCString(rt->ctx, stack);
             fprintf(stderr, "[js] act() error: %s\n%s\n", str, stack_str ? stack_str : "");
             ac_log("[js] act() error: %s\n%s\n", str, stack_str ? stack_str : "");
+            js_record_crash(rt, "act", str);
             if (stack_str) JS_FreeCString(rt->ctx, stack_str);
             JS_FreeValue(rt->ctx, stack);
             JS_FreeCString(rt->ctx, str);
@@ -5425,6 +5435,7 @@ void js_call_sim(ACRuntime *rt) {
         JSValue stack = JS_GetPropertyStr(rt->ctx, exc, "stack");
         const char *stack_str = JS_ToCString(rt->ctx, stack);
         fprintf(stderr, "[js] sim() error: %s\n%s\n", str, stack_str ? stack_str : "");
+        js_record_crash(rt, "sim", str);
         if (stack_str) JS_FreeCString(rt->ctx, stack_str);
         JS_FreeValue(rt->ctx, stack);
         JS_FreeCString(rt->ctx, str);
diff --git a/fedac/native/src/js-bindings.h b/fedac/native/src/js-bindings.h
index 171bc539b0..d98f9ce6cd 100644
--- a/fedac/native/src/js-bindings.h
+++ b/fedac/native/src/js-bindings.h
@@ -100,6 +100,13 @@ typedef struct {
     // User config (read from /mnt/config.json on EFI partition)
     char handle[64];                     // e.g. "jeffrey" (without @)
     char piece[64];                      // default piece name, e.g. "notepat"
+
+    // JS crash overlay — set when paint/act/sim throws an unhandled exception
+    int  crash_active;                   // 1 = crash bar visible
+    int  crash_count;                    // total JS exceptions since piece load
+    char crash_msg[256];                 // last error message
+    char crash_piece[64];               // piece that crashed
+    int  crash_frame;                    // frame counter for animation
 } ACRuntime;
 
 // Initialize QuickJS and register all AC API bindings