Stage I: strip dead code -- pump drain loop, SWITCH-MARK-WORK, global interpret depth, native_switch_back_to (FABRIC-3.8 §4 row I)

Each shown dead three ways (FABRIC-3.5 §XXII): the pump loop by its
condition, by construction (birth cap == switch table capacity, every birth
registers) and at run time (probe silent through boot, G interleave, an
8-worker DoE trial and the relay); SWITCH-MARK-WORK by callers, capsules
(source and baked), experiments/tools/logs; the depth counter and back_to
field by having no readers.

Kept: Hera's own pump drain (last timer-paced delivery, Hera only) and the
always-0 readiness CSV columns (a DoE schema call). Acceptance on amd64/
aarch64/riscv64: G interleave unchanged, cfg-0 trial fail=0 2/2 dead,
relay 3, idle growth 0; dict_hash set changed by the removed word
(word_count 531) and identical across ISAs. FABRIC-3.8 stages A-I done.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

FABRIC-3.8.md

@@ -1325,3 +1325,49 @@ explicit instruction.
         observation, not investigated.
       - Stage F's remaining evidence (work proceeds with the console idle) is shown by Stage G's
         interleave and by these trials.
+- [x] **Stage I — strip the dead code (§4 row I).** 2026-09-24. Captain Bob: *"go ahead with
+      stage I."* Per `FABRIC-3.5.md` §XXII's discipline, each removal's reachability was shown
+      three ways, not by grep alone.
+
+      **Removed:**
+
+      | Item | Why dead |
+      |---|---|
+      | **The idle pump's drain loop** (`repl.c`, `sk_repl_idle()`), which drained every non-Hera live VM on Hera's stack (G3) | (1) **Static:** since C-b it acted only on a live **non-participant**. (2) **Construction:** births are refused at `stadium_max_vm_count()` live VMs (`capsule_birth.c:731`), the same capacity as the switch-signal table. Every birth registers (Stage E), stillborn VMs never go live, and `KILL`/reap unregister, so registration can't fail and no live non-participant can exist. (3) **Runtime:** a probe line in that branch (temporary, removed) printed **nothing** through a boot, the Stage G interleave, a full 8-worker cfg-4 trial (`fail=0`, 8/8 dead) and the WIREBIND relay (`logs/20260924-051657/amd64/`). |
+      | **`SWITCH-MARK-WORK`** (the word, `mama_word_switch_mark_work`, and `sk_vm_switch_signal_mark_work()`) | (1) Its only caller, `MSG-SEND` in `capsules/common/messaging.4th`, was deleted in `FABRIC-3.6.md` Phase 4. (2) No capsule source, no baked capsule (`capsule_generated.c`: 0), no experiment, tool or committed log invokes it; only the design docs mention it. (3) Since C-b, eligibility **is** the queue, so the word had nothing left to mark. |
+      | **The global interpret depth** (`g_vm_interpret_depth`, `sk_vm_at_outermost_interpret()`) | No caller since Stage A replaced it with the per-VM ownership gate. Only comments referred to it; they're updated. |
+      | **`VM.native_switch_back_to`** (`vm.h`) | Written by `sk_vm_context_switch()`, read by nothing since C-b's trampoline stopped yielding to "whoever switched in" (the Stage B/FR probes, which read it, are long reverted). |
+
+      **Kept, deliberately:**
+      - **Hera's own drain in the idle pump.** She is the one VM never switched to for her mail,
+          since she's the one running there. It still runs at the `SK_IDLE_BEAT_INTERVAL`
+          (timer-paced) cadence, and at her own word checkpoints. **This is the last
+          timer-paced delivery left, and it applies only to Hera's own queue.** Moving it to
+          `sk_vm_idle_point()` would need care with the readline `n > 0` mid-edit gate. Noted for
+          Captain Bob.
+      - **The three `*_readiness` DoE CSV columns** (always 0 since C-b). Dropping them changes
+          the CSV layout the extractor and analysis read. That's a DoE-schema decision for the
+          campaign relaunch, not a dead-code strip.
+
+      **Acceptance** (on every ISA: the Stage G interleave, a cfg-0 DoE trial, then the relay):
+      `logs/20260924-054146/amd64/`, `-055249/aarch64/`, `-061024/riscv64/`.
+      - The G interleave is byte-identical to Stage H on all three (A = 40, B = 40, 48 runs).
+      - `MU-TRIAL … cfg=0 … nw=2 … fail=0`, with 2/2 `KILL … dead` and 0 refused.
+      - All reach `[zuse@Hera] ok>` with zero `UNKNOWN WORD`, failures and faults.
+      - Mint → WIREBIND → `USE` → `1 2 + .` → `3`.
+      - Idle log growth: 0 bytes.
+      - Clean build on all three plus hosted (`vm.h` is shared), no new warnings.
+      - **The `dict_hash` set changes, as expected, because `SWITCH-MARK-WORK` is gone, and is
+        identical across ISAs.** `word_count` drops by 2 because the word was registered twice
+        in Hera's dictionary.
+
+        | | New | Stages G/H |
+        |---|---|---|
+        | `word_count` | 531 | 533 |
+        | M7.1a | `0x572daac83b797332` | `0x330b28ce0f4e1c75` |
+        | Hera | `0xda9742ce9c3376a2` | |
+        | Hestia | `0x413e7d086f342d8b` | |
+        | Artemis | `0xdfd68316d5f5ba85` | |
+
+      **FABRIC-3.8's staged plan (A–I) is complete.** What's next is the per-ISA DoE relaunch
+      (seed 12345, 3 reps) on the rebuilt driver, then the merge to master.

capsules/BLOCK_MAP.md

@@ -1,5 +1,5 @@
 # Capsule Block Manifest — Auto-generated
-<!-- Generated by mkcapsule --manifest  2026-09-24T03:15:17Z -->
+<!-- Generated by mkcapsule --manifest  2026-09-24T10:09:49Z -->
 <!-- DO NOT EDIT — re-run mkcapsule --manifest to refresh.  -->
 <!-- Hand-written justifications and immutability notes live  -->
 <!-- in MANIFEST.md alongside this auto-generated index.      -->

include/starkernel/capsule_vm_switch_signal.h

@@ -169,10 +169,6 @@ void sk_vm_switch_reap_pending(void);
  * CSV counters below. */
 void sk_vm_switch_signal_note_switch_performed(VMUuid target_id);
 
-/* SWITCH-MARK-WORK's body. Stage C-b: no flag to set any more (the queue
- * is the eligibility); only asks for a fresh decision. */
-void sk_vm_switch_signal_mark_work(VMUuid vm_id);
-
 /* DoE CSV read-only exposure (FABRIC-3.md §XXVIII Stage 3 follow-on,
  * 2026-09-13). Stage C-b: ticks_since_switch now counts beats of the
  * running VM since the last switch (§3.13.4), not ISR ticks; the per-VM

include/starkernel/vm/kernel_hermes.h

@@ -543,7 +543,9 @@ typedef struct VM VM;
  * one message per checkpoint, ruled 2026-09-21). Called from
  * execute_colon_word()'s existing cooperative checkpoint in vm_core.c,
  * gated the same way the switch-signal checkpoint already is
- * (sk_vm_at_outermost_interpret()).
+ * (sk_vm_at_outermost_interpret() then; since FABRIC-3.8.md Stage A the
+ * per-VM sk_vm_owns_outermost_frame(), and the global counter is removed,
+ * Stage I).
  *
  * AMENDS SXLIII.5's own claim: "recursive drain is prevented for free"
  * via g_vm_interpret_depth is true (the SAME message cannot drain twice),

include/vm.h

@@ -659,17 +659,6 @@ typedef struct VM
                                          *   entered (no context parked yet); non-zero only
                                          *   while VMRegistryEntry.state ==
                                          *   VM_STATE_SWITCHED_OUT for this VM. */
-    struct VM *native_switch_back_to;  /**< Stage 3 correction (FABRIC-3.md §XXVIII,
-                                         *   2026-09-13): who most recently switched INTO
-                                         *   this VM. Updated by sk_vm_context_switch() on
-                                         *   every switch-in (first-ever or resumed), so the
-                                         *   placeholder trampoline (sk_vm_switch_entry())
-                                         *   always yields back to whoever actually switched
-                                         *   in, not a stale value captured once at this
-                                         *   VM's very first entry -- a single global there
-                                         *   let a later switch-in from a different VM get
-                                         *   silently bounced to the original caller instead
-                                         *   of itself. */
     VMFrameStack frames;               /**< FABRIC-3.8.md §3.12 (Stage FR, 2026-09-23):
                                          *   this VM's execution frame stack -- the nested
                                          *   levels running on its own native stack, each

src/starkernel/capsule/capsule_vm_switch_signal.c

@@ -333,15 +333,6 @@ void sk_vm_switch_signal_note_switch_performed(VMUuid target_id) {
     g_beats_since_switch = 0;
 }
 
-void sk_vm_switch_signal_mark_work(VMUuid vm_id) {
-    /* Stage C-b: eligibility is read from the kernel-Hermes queue itself,
-     * so there is no has_work flag to set. Kept (SWITCH-MARK-WORK still
-     * calls it) as a "something changed, decide again" hint; Stage I
-     * strips it if nothing calls it. */
-    (void)vm_id;
-    g_decision_due = 1;
-}
-
 uint64_t sk_vm_switch_signal_switch_count(void) {
     return g_switch_count;
 }

src/starkernel/capsule/mama_forth_words.c

@@ -56,7 +56,6 @@
 #include "starkernel/capsule_vm_physics.h"
 #include "starkernel/vm/vm_internal.h"
 #include "starkernel/vm/stadium.h" /* item 4.2 -- STADIUM-* words */
-#include "starkernel/capsule_vm_switch_signal.h" /* FABRIC-3.md §XXVIII Stage 3 follow-on -- SWITCH-MARK-WORK */
 #include "starkernel/vm/stadium_words.h" /* item 4.2 -- stadium_words_resident_heat() */
 #include "starkernel/repl.h"
 #include "starkernel/capsule_generated.h"
@@ -832,47 +831,12 @@ static void mama_word_vm_exec(VM *vm)
     /* Stack clean on exit */
 }
 
-/**
- * @brief SWITCH-MARK-WORK ( name-caddr name-u -- )
- * FABRIC-3.md §XXVIII Stage 3 follow-on (2026-09-14): message-arrival
- * eligibility hook. Called from MSG-SEND (capsules/common/messaging.4th)
- * every time a message is sent to a VM, so the Stage 3 switch signal can
- * tell "has recently been sent something" apart from "has just been idle
- * long enough" before ever selecting it as a switch target. Silently
- * ignores a malformed or unknown name -- this fires on the hot path of
- * every message send, not a user-facing command, so it must never error
- * or spam the console.
- */
-static void mama_word_switch_mark_work(VM *vm)
-{
-    char        name[VM_NAME_MAX];
-    cell_t      u, caddr;
-    uint32_t    i;
-    VMRegistryEntry entry;
-
-    /* FABRIC-3.md §XXXII.6, 2026-09-15: this guard used to set vm->error on
-     * underflow, contradicting this function's own doc comment above ("must
-     * never error or spam the console") -- flagged as a special case in
-     * §XXXII.3's triage, not just a missing diagnostic. Silently ignored,
-     * matching every other malformed-input case in this same function. */
-    if (vm->dsp < 1) return;
-
-    u     = vm_pop(vm);
-    caddr = vm_pop(vm);
-
-    if (u <= 0 || (uint32_t)u >= VM_NAME_MAX) return;
-
-    {
-        const uint8_t *p = vm_ptr(vm, (vaddr_t)caddr);
-        if (!p) return;
-        for (i = 0; i < (uint32_t)u; i++) name[i] = (char)p[i];
-        name[u] = '\0';
-    }
-
-    if (capsule_vm_find_by_name_nocase(name, &entry) == 0) {
-        sk_vm_switch_signal_mark_work(entry.vm_id);
-    }
-}
+/* SWITCH-MARK-WORK (FABRIC-3.md §XXVIII Stage 3 follow-on) was removed at
+ * FABRIC-3.8.md Stage I (2026-09-24). Its only caller, MSG-SEND in
+ * capsules/common/messaging.4th, was deleted in FABRIC-3.6.md Phase 4; since
+ * Stage C-b a VM's eligibility is its kernel-Hermes queue itself, so there
+ * is nothing left for it to mark. No capsule (source or baked), experiment,
+ * tool or committed log invokes it. */
 
 /**
  * @brief VM-CALL ( cmd-caddr cmd-u vm-name-caddr vm-name-u -- n )
@@ -2393,7 +2357,6 @@ void register_mama_forth_words(VM *vm)
     register_word(vm, "VM-PHYSICS-STATUS", mama_word_vm_physics_status);
     register_word(vm, "VM-STEP", mama_word_vm_step);
     register_word(vm, "VM-EXEC", mama_word_vm_exec);
-    register_word(vm, "SWITCH-MARK-WORK", mama_word_switch_mark_work);
     register_word(vm, "VM-CALL", mama_word_vm_call);
     register_word(vm, "VM-HEAT", mama_word_vm_heat);
     register_word(vm, "VM-ERROR?", mama_word_vm_error_query);
@@ -2458,7 +2421,6 @@ void register_mama_forth_words(VM *vm)
     register_word(vm, "VM-PHYSICS-STATUS", mama_word_vm_physics_status);
     register_word(vm, "VM-STEP", mama_word_vm_step);
     register_word(vm, "VM-EXEC", mama_word_vm_exec);
-    register_word(vm, "SWITCH-MARK-WORK", mama_word_switch_mark_work);
     register_word(vm, "VM-CALL", mama_word_vm_call);
     register_word(vm, "VM-HEAT", mama_word_vm_heat);
     register_word(vm, "VM-ERROR?", mama_word_vm_error_query);
@@ -2719,7 +2681,6 @@ void register_child_vm_words(VM *vm)
     register_word(vm, "STOP",    mama_word_stop);
     register_word(vm, "EXEC",    mama_word_exec);
     register_word(vm, "VM-EXEC", mama_word_vm_exec);
-    register_word(vm, "SWITCH-MARK-WORK", mama_word_switch_mark_work);
     register_word(vm, "VM-CALL", mama_word_vm_call);
     register_word(vm, "VM-HEAT", mama_word_vm_heat);
     register_word(vm, "VM-ERROR?", mama_word_vm_error_query);

src/starkernel/repl.c

@@ -47,7 +47,6 @@
 #include "starkernel/vm/bootstrap/sk_vm_bootstrap.h"
 #include "starkernel/vm/kernel_hermes.h" /* FABRIC-3.6.md task 3.8 -- sk_hermes_send_one() */
 #include "starkernel/vm/switch.h" /* FABRIC-3.8.md §3.13.5 -- sk_vm_idle_point() */
-#include "starkernel/capsule_vm_switch_signal.h" /* §3.13.5 -- pump skips participants */
 #include "starkernel/vm/stadium.h" /* task 3.8 -- stadium_conserved() evidence print */
 #include "block_subsystem.h"
 #include "word_source/include/keyboard_words.h"
@@ -954,48 +953,18 @@ static void sk_repl_idle(VM *active_vm)
     }
 
     g_idle_pump_active = 1;
-    {
-        /* FABRIC-3.6.md Phase 4 (Stage E), 2026-09-22: the SK_MSG_PUMP_
-         * BATCH cap this loop used to enforce existed to bound the cost
-         * of the old MSG-TICK VM-EXEC dispatch -- a genuinely expensive
-         * per-VM vm_interpret() call, confirmed live as a real O(N)
-         * bottleneck at just 9 VMs on riscv64 (see this section's own
-         * history above). sk_hermes_drain_checkpoint() (task 3.4) is not
-         * that: its own fast path is a single global-counter read
-         * (sk_hermes_pending_total == 0 -> return immediately,
-         * kernel_hermes.c's own doc comment), so walking every live VM
-         * every beat costs one cheap integer read per VM in the common
-         * case (nothing in flight), not an O(N) wall -- the cap this
-         * loop's own comment history worried about does not apply to
-         * this call. Removed: every live VM (except mama, handled
-         * separately below) is now visited every idle beat, matching
-         * what task 3.9's own testing already exercised, without the
-         * ceil(N/SK_MSG_PUMP_BATCH)-beat delivery latency the cap was
-         * accidentally imposing on kernel-Hermes drain specifically. */
-        uint32_t count = capsule_vm_registry_count();
-        uint32_t i;
-
-        for (i = 0; i < count; i++) {
-            VMRegistryEntry ent;
-            /* FABRIC-3.8.md §3.4 / §3.13.5 (Stage C-b, G3): switch
-             * participants are skipped -- their mail is delivered on their
-             * own stacks, by a switch (sk_vm_idle_point() and the trampoline),
-             * never drained here on Hera's. Only VMs not yet participants
-             * (Stage E makes every born VM one) are still pumped here. */
-            if (capsule_vm_registry_get_by_index(i, &ent) == 0 &&
-                ent.state == VM_STATE_LIVE &&
-                ent.vm_ptr != (void *)mama &&
-                !sk_vm_switch_signal_is_participant(ent.vm_id)) {
-                (void)sk_hermes_drain_checkpoint((VM *)ent.vm_ptr);
-            }
-        }
-    }
-    /* Hera's own kernel-Hermes queue needs draining too, same as every
-     * other VM's -- she is excluded from the loop above not because she
-     * has nothing to drain, but because she IS the pump: a self-
-     * targeting call here runs directly, no VM-EXEC/reentrancy concern
-     * (sk_hermes_drain_checkpoint() is a plain C call, not a dispatch
-     * into anyone else's input buffer). */
+    /* FABRIC-3.8.md Stage I (2026-09-24): the loop that used to drain every
+     * other live VM's queue here, on Hera's stack (G3), is removed. Since
+     * Stage E every born VM is a switch participant -- births are capped at
+     * stadium_max_vm_count() live VMs (capsule_birth.c), the same capacity
+     * as the switch-signal table, so registration cannot fail -- and a
+     * participant's mail is delivered on its own stack by a switch, never
+     * here. Shown dead three ways before removal: by the condition it
+     * required (a live non-participant), by that construction, and at run
+     * time (a probe printed nothing through a boot, the Stage G interleave,
+     * a full 8-worker DoE trial and the WIREBIND relay). What remains is
+     * Hera's own queue: she is the one VM that is never switched to for her
+     * mail, since she is the one running here. */
     (void)sk_hermes_drain_checkpoint(mama);
     g_idle_pump_active = 0;
 

src/starkernel/vm/switch.c

@@ -49,8 +49,9 @@ extern uint64_t sk_vm_switch_prime(uint64_t stack_top, void *entry);
  * native stack belongs to. Read exactly once, synchronously, at the very
  * top of sk_vm_switch_entry() before any other first-entry could occur.
  * Safe to keep as a plain global (unlike the old g_switch_back_to this
- * file used to also carry -- see native_switch_back_to's own doc comment
- * in vm.h for why that one had to move to per-VM state): a VM's identity
+ * file used to also carry, which moved to per-VM native_switch_back_to and
+ * was then removed at FABRIC-3.8.md Stage I once the trampoline stopped
+ * yielding to "whoever switched in"): a VM's identity
  * never changes across the lifetime of its own trampoline instance, only
  * who most recently switched into it does. */
 static VM *g_switch_entry_vm;
@@ -236,11 +237,6 @@ int sk_vm_context_switch(VM *from, VM *to) {
         return -1;
     }
 
-    /* Recorded unconditionally (first-ever entry or a resume) so whoever
-     * is parked at `to`'s native stack -- most often this placeholder
-     * trampoline -- always knows who most recently switched into it. */
-    to->native_switch_back_to = from;
-
     if (to->native_stack_saved_sp == 0) {
         /* First-ever entry: synthesize the initial frame. */
         g_switch_entry_vm = to;

src/starkernel/vm/vm_core.c

@@ -65,11 +65,6 @@
 #include "starkernel/vm/kernel_hermes.h" /* FABRIC-3.6.md task 3.4 -- sk_hermes_drain_checkpoint() */
 #include "starkernel/capsule_birth.h" /* capsule_vm_registry_get() */
 
-/* FABRIC-3.md §XXVIII Stage 3 correction (2026-09-13): forward-declared
- * here because execute_colon_word() (uses it) appears earlier in this file
- * than g_vm_interpret_depth's definition (kept next to g_log_attrib_vm,
- * near vm_interpret() -- see that doc comment for the full rationale). */
-int sk_vm_at_outermost_interpret(void);
 int sk_vm_owns_outermost_frame(VM *vm); /* FABRIC-3.8.md §3.1 -- defined near vm_interpret() */
 #endif
 #include "word_source/include/vocabulary_words.h"
@@ -940,8 +935,9 @@ void execute_colon_word(VM* vm)
          * so a switch never happens mid-unwind).
          *
          * Stage 3 correction (2026-09-13): also gated on
-         * sk_vm_at_outermost_interpret() -- see g_vm_interpret_depth's own
-         * doc comment above vm_interpret(). If this word is executing
+         * sk_vm_at_outermost_interpret() (a global depth count, removed at
+         * FABRIC-3.8.md Stage I -- superseded by the ownership gate
+         * below). If this word is executing
          * nested inside a VM-EXEC/VM-CALL dispatch (from another VM's own
          * vm_interpret() call, still on the mainline stack), `vm` here does
          * not own the physical stack it's currently running on, so a real
@@ -1174,19 +1170,11 @@ VM *vm_log_attributed_vm(void) {
     return (VM *)e.vm_ptr;
 }
 
-/* FABRIC-3.md §XXVIII Stage 3 correction (2026-09-13): nesting depth of
- * vm_interpret() calls, tracked the same save/restore-adjacent way as
- * g_log_attrib_vm just above. A nested call (VM-EXEC/VM-CALL dispatching
- * into a different VM's own dictionary mid-interpret) runs on physical
- * stack memory it does not own -- the Stage 3 switch checkpoint in
- * execute_colon_word() below must never fire a real context switch there,
- * only at the outermost vm_interpret() call, or it parks a borrowed stack
- * region under the wrong VM's saved-context pointer (silent corruption,
- * not just the trampoline livelock this was first found chasing -- see
- * FABRIC-3.md for the full writeup). */
-static int g_vm_interpret_depth;
-
-int sk_vm_at_outermost_interpret(void) { return g_vm_interpret_depth <= 1; }
+/* FABRIC-3.8.md Stage I (2026-09-24): the global vm_interpret() nesting
+ * depth (g_vm_interpret_depth / sk_vm_at_outermost_interpret(), FABRIC-3.md
+ * §XXVIII Stage 3) that used to live here is removed. It only approximated
+ * the per-VM ownership rule below, and stopped meaning anything once VMs
+ * interleave on their own stacks; since Stage A nothing read it. */
 
 /* FABRIC-3.8.md §3.1 (Stage A, 2026-09-23): the real ownership invariant
  * the global depth test above was approximating. A checkpoint may drain or
@@ -1252,7 +1240,6 @@ void vm_interpret_kind(VM* vm, const char* input, uint32_t kind)
         vm->error = 1;
         return;
     }
-    g_vm_interpret_depth++;
 
     /* Load into input buffer (cap + NUL) */
     size_t n = 0, cap = INPUT_BUFFER_SIZE ? INPUT_BUFFER_SIZE - 1 : 0;
@@ -1303,7 +1290,6 @@ void vm_interpret_kind(VM* vm, const char* input, uint32_t kind)
 #endif
     }
 
-    g_vm_interpret_depth--;
     vm_frame_pop(frame_stack, frame_id); /* by ID -- a mismatch is logged as corruption */
 }