diff --git a/TODO.org b/TODO.org
index a76e8535..8ac565ac 100644
--- a/TODO.org
+++ b/TODO.org
@@ -1122,10 +1122,12 @@ so a =declare-c= wrapper leaning on the courtesy is already backend-dependent as
 well as slice-dependent. The contract is pointer and length, and nothing promised
 otherwise.
 
-** NEXT Frame descriptions are gated on --debug
-Decided 2026-09-25: emit the x86 backend's =.cfi= directives in every build. No runtime cost; the lane measures the =.eh_frame= size it adds.
-They are correct in every build and free at runtime, and a release build is where
-a crash would most want them. One =if= in three places.
+** DONE Frame descriptions are gated on --debug
+CLOSED: [2026-09-25]
+The x86 backend emits its =.cfi= directives in every build, redefinition modules
+included, so an unwinder never has to guess at a Flan frame. Cost: about 40 bytes
+of =.eh_frame= and =.eh_frame_hdr= per function, 2 KB on =json.flan='s 210 KB
+binary.
 
 ** TODO A !DILexicalBlock per Let
 Inside nested =let=s that bind the same name, a debugger still answers with the
diff --git a/lib/x86.ml b/lib/x86.ml
index 8202c26d..168c54cc 100644
--- a/lib/x86.ml
+++ b/lib/x86.ml
@@ -3454,12 +3454,8 @@ and cast f (a : Tast.expr) (target : Types.t) dst =
    the return address is column 16 and the CIE already says it is at
    [cfa-8].
 
-   Emitted only in a [--debug] build, so that a release build's assembly stays
-   byte-for-byte what it was. That is a conservative call rather than a
-   principled one: this description is correct in every build, and a release
-   build is where an unwind through a crash would most want it. What stops it
-   from being unconditional today is only that nothing measures the [.eh_frame]
-   it would add. *)
+   Emitted in every build, [--debug] or not. It costs nothing at run time,
+   and a release build is where an unwind through a crash most wants it. *)
 let cfi_after_push b = text b "\t.cfi_def_cfa_offset 16\n\t.cfi_offset 6, -16\n"
 let cfi_after_mov b = text b "\t.cfi_def_cfa_register 6\n"
 let cfi_after_leave b = text b "\t.cfi_def_cfa 7, 8\n"
@@ -3711,7 +3707,6 @@ let emit_fn (md : Emit.m) ~externs ~fns ?(ext = fun _ -> false)
      column even when it is on the same line, so it gets a row of its own, and
      two rows are what let a debugger put a breakpoint after the prologue
      rather than on it. *)
-  let cfi = match dw with None -> false | Some _ -> true in
   let sub =
     match dw with
     | None -> None
@@ -4069,9 +4064,9 @@ let emit_fn (md : Emit.m) ~externs ~fns ?(ext = fun _ -> false)
       % 16 == 0 at every call site below is a property of that one rounded sub rather \
       than an invariant each case has to keep.";
   push_r pb rbp;
-  if cfi then cfi_after_push pb;
+  cfi_after_push pb;
   mov_rr pb ~dst:rbp ~src:rsp;
-  if cfi then cfi_after_mov pb;
+  cfi_after_mov pb;
   let n = frame_bytes f in
   if n > 0 then sub_imm pb ~dst:rsp n;
   (match sret_at with
@@ -4184,7 +4179,7 @@ let emit_fn (md : Emit.m) ~externs ~fns ?(ext = fun _ -> false)
     load_scalar f ~reg:(if is_float fn.Tast.ret then xmm0 else rax)
       ~off:f.retval fn.Tast.ret;
   leave f.b;
-  if cfi then cfi_after_leave f.b;
+  cfi_after_leave f.b;
   ret f.b;
   flush pb;
   flush f.b;
@@ -4206,7 +4201,7 @@ let emit_fn (md : Emit.m) ~externs ~fns ?(ext = fun _ -> false)
   if hidden then Buffer.add_string out (Printf.sprintf "\t.hidden\t%s\n" sym);
   Buffer.add_string out (Printf.sprintf "\t.type\t%s, @function\n" sym);
   Buffer.add_string out (sym ^ ":\n");
-  if cfi then Buffer.add_string out "\t.cfi_startproc\n";
+  Buffer.add_string out "\t.cfi_startproc\n";
   Buffer.add_string out (Buffer.contents pb.out);
   Buffer.add_string out (Buffer.contents f.b.out);
   (* One past the last byte, which is what [DW_AT_high_pc] and the line
@@ -4217,7 +4212,7 @@ let emit_fn (md : Emit.m) ~externs ~fns ?(ext = fun _ -> false)
    | Some s -> Buffer.add_string out (s.send ^ ":\n")
    | None -> ());
   (match dw with Some d -> d.dcur <- None | None -> ());
-  if cfi then Buffer.add_string out "\t.cfi_endproc\n";
+  Buffer.add_string out "\t.cfi_endproc\n";
   Buffer.add_string out (Printf.sprintf "\t.size\t%s, . - %s\n\n" sym sym);
   Buffer.contents out, Buffer.contents f.rodata
 
@@ -4254,7 +4249,7 @@ let init_sym = asm_sym (Mangle.sym ".init-globals")
    the loader put them in, the program's own end of the transfer channel is a
    null cell on this frame, and the exit goes through [flan_exit] because
    stdout is a FILE* and something has to flush it. *)
-let emit_main ?(cfi = false) ?(ann = false) ?(startup = false) ?(gc = false)
+let emit_main ?(ann = false) ?(startup = false) ?(gc = false)
       ?(dyn_globals = []) (md : Emit.m) (fn : Tast.fn) =
   let b = create () in
   bnote ann b
@@ -4266,9 +4261,9 @@ let emit_main ?(cfi = false) ?(ann = false) ?(startup = false) ?(gc = false)
       and something has to flush it. The ud2 at the end is unreachable — flan_exit does \
       not return.";
   push_r b rbp;
-  if cfi then cfi_after_push b;
+  cfi_after_push b;
   mov_rr b ~dst:rbp ~src:rsp;
-  if cfi then cfi_after_mov b;
+  cfi_after_mov b;
   sub_imm b ~dst:rsp 48;
   (* [al] is zero at every call this backend makes, variadic or not — see
      [call_native]. Setting it here too costs two bytes and keeps the rule
@@ -4380,9 +4375,9 @@ let emit_main ?(cfi = false) ?(ann = false) ?(startup = false) ?(gc = false)
      it leaves through [flan_exit] and the [ud2] after that is unreachable.
      The rbp rule therefore holds to the last byte, which is what a backtrace
      out of anything [main] called needs. *)
-  if cfi then Buffer.add_string out "\t.cfi_startproc\n";
+  Buffer.add_string out "\t.cfi_startproc\n";
   Buffer.add_string out (Buffer.contents b.out);
-  if cfi then Buffer.add_string out "\t.cfi_endproc\n";
+  Buffer.add_string out "\t.cfi_endproc\n";
   Buffer.add_string out "\t.size\tmain, . - main\n\n";
   Buffer.contents out
 
@@ -4409,7 +4404,7 @@ let emit_globals_data (md : Emit.m) (globals : Tast.global list) =
   Buffer.contents out
 
 
-let emit_globals_init ?(cfi = false) ?(ann = false) ?body ~sym (md : Emit.m) ~externs ~fns
+let emit_globals_init ?(ann = false) ?body ~sym (md : Emit.m) ~externs ~fns
       (globals : Tast.global list) =
   let b = create () in
   let f =
@@ -4454,9 +4449,9 @@ let emit_globals_init ?(cfi = false) ?(ann = false) ?body ~sym (md : Emit.m) ~ex
   end;
   let pb = create () in
   push_r pb rbp;
-  if cfi then cfi_after_push pb;
+  cfi_after_push pb;
   mov_rr pb ~dst:rbp ~src:rsp;
-  if cfi then cfi_after_mov pb;
+  cfi_after_mov pb;
   let n = frame_bytes f in
   if n > 0 then sub_imm pb ~dst:rsp n;
   (* No caller hands this one a channel, so it gets a null cell of its own and
@@ -4467,16 +4462,16 @@ let emit_globals_init ?(cfi = false) ?(ann = false) ?body ~sym (md : Emit.m) ~ex
   store_int pb ~src:rax ~mm:(Frame f.xfer_off) ~size:8;
   lbl f.b f.retlbl;
   leave f.b;
-  if cfi then cfi_after_leave f.b;
+  cfi_after_leave f.b;
   ret f.b;
   flush pb; flush f.b;
   let out = Buffer.create 512 in
   Buffer.add_string out
     (Printf.sprintf "\t.type\t%s, @function\n%s:\n" sym sym);
-  if cfi then Buffer.add_string out "\t.cfi_startproc\n";
+  Buffer.add_string out "\t.cfi_startproc\n";
   Buffer.add_string out (Buffer.contents pb.out);
   Buffer.add_string out (Buffer.contents f.b.out);
-  if cfi then Buffer.add_string out "\t.cfi_endproc\n";
+  Buffer.add_string out "\t.cfi_endproc\n";
   Buffer.add_string out (Printf.sprintf "\t.size\t%s, . - %s\n\n" sym sym);
   Buffer.contents out, Buffer.contents f.rodata
 
@@ -4832,7 +4827,7 @@ let program ~checks ?(dev = false) ?(debug = false) ?(annotate = false)
   in
   let computed, init_flags, init_body = Emit.startup_plan md p.Tast.globals in
   let ginit, gr =
-    emit_globals_init ~cfi:debug ~ann:annotate ~sym:data_sym md ~externs ~fns
+    emit_globals_init ~ann:annotate ~sym:data_sym md ~externs ~fns
       constants
   in
   Buffer.add_string text ginit;
@@ -4840,7 +4835,7 @@ let program ~checks ?(dev = false) ?(debug = false) ?(annotate = false)
   let startup = computed <> [] in
   if startup then begin
     let t, r =
-      emit_globals_init ~cfi:debug ~ann:annotate ~body:init_body ~sym:init_sym
+      emit_globals_init ~ann:annotate ~body:init_body ~sym:init_sym
         md ~externs ~fns computed
     in
     Buffer.add_string text t;
@@ -4849,7 +4844,7 @@ let program ~checks ?(dev = false) ?(debug = false) ?(annotate = false)
   (match List.find_opt (fun (f : Tast.fn) -> f.Tast.name = "main") p.Tast.fns with
    | Some fn ->
      Buffer.add_string text
-       (emit_main ~cfi:debug ~ann:annotate ~startup ~gc:(Emit.uses_dyn p)
+       (emit_main ~ann:annotate ~startup ~gc:(Emit.uses_dyn p)
           ~dyn_globals:
             (List.filter_map
                (fun (g : Tast.global) ->
@@ -5217,7 +5212,9 @@ let redefinition ~checks ?(dev = true) ?(known = fun _ -> true)
   end;
   let pb = create () in
   push_r pb rbp;
+  cfi_after_push pb;
   mov_rr pb ~dst:rbp ~src:rsp;
+  cfi_after_mov pb;
   let n = frame_bytes f in
   if n > 0 then sub_imm pb ~dst:rsp n;
   xor_rr pb ~dst:rax ~src:rax;
@@ -5226,17 +5223,18 @@ let redefinition ~checks ?(dev = true) ?(known = fun _ -> true)
   store_int pb ~src:rax ~mm:(Frame f.xfer_off) ~size:8;
   lbl f.b f.retlbl;
   leave f.b;
+  cfi_after_leave f.b;
   ret f.b;
   flush pb;
   flush f.b;
   Buffer.add_string text
     "\t.globl\tflan_reload_install\n\
      \t.type\tflan_reload_install, @function\n\
-     flan_reload_install:\n";
+     flan_reload_install:\n\t.cfi_startproc\n";
   Buffer.add_buffer text pb.out;
   Buffer.add_buffer text f.b.out;
   Buffer.add_string text
-    "\t.size\tflan_reload_install, . - flan_reload_install\n\n";
+    "\t.cfi_endproc\n\t.size\tflan_reload_install, . - flan_reload_install\n\n";
   (* An expression evaluation compiles to a function with nowhere to be called
      from, so the module says so and the agent runs it once -- after the
      install, on the game thread, so it sees both the bodies this module just
@@ -5252,7 +5250,9 @@ let redefinition ~checks ?(dev = true) ?(known = fun _ -> true)
    | Some fn ->
      let cb = create () in
      push_r cb rbp;
+     cfi_after_push cb;
      mov_rr cb ~dst:rbp ~src:rsp;
+     cfi_after_mov cb;
      sub_imm cb ~dst:rsp 16;
      xor_rr cb ~dst:rax ~src:rax;
      store_int cb ~src:rax ~mm:(Frame (-8)) ~size:8;
@@ -5260,15 +5260,16 @@ let redefinition ~checks ?(dev = true) ?(known = fun _ -> true)
      xor_rr cb ~dst:rax ~src:rax;
      call_sym cb (fsym fn);
      leave cb;
+     cfi_after_leave cb;
      ret cb;
      flush cb;
      Buffer.add_string text
        "\t.globl\tflan_reload_call\n\
         \t.type\tflan_reload_call, @function\n\
-        flan_reload_call:\n";
+        flan_reload_call:\n\t.cfi_startproc\n";
      Buffer.add_buffer text cb.out;
      Buffer.add_string text
-       "\t.size\tflan_reload_call, . - flan_reload_call\n\n");
+       "\t.cfi_endproc\n\t.size\tflan_reload_call, . - flan_reload_call\n\n");
   Buffer.add_buffer rodata f.rodata;
   let out = Buffer.create 8192 in
   Buffer.add_buffer out text;