Stage E: every born VM is a switch participant (FABRIC-3.8 §3.6, G4)

capsule_birth_baby() registers each VM at its LIVE completion point, beside
the common-channel subscription. register() is idempotent. The Artemis/
Hestia registrations in kernel_main.c and WIREBIND's own call are removed
(Hera, never born through capsule_birth_baby, stays with set_current).

Probe (restored away): Tripod registered once each (3 slots), a
WORKER-BIRTH VM becomes a participant with no hand registration (4) and
KILL frees it (3), WIREBIND registers exactly console+user, zero
duplicates, on amd64/aarch64/riscv64. Acceptance: dict_hash unchanged,
relay 3, idle growth 0.

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

FABRIC-3.8.md

@@ -1052,3 +1052,54 @@ explicit instruction.
       - WIREBIND's detach path calls `capsule_vm_kill()` directly, without the `KILL` word's
         `vm_physics_retire()`. I have not checked whether a detached identity's VM-physics heat
         is retired elsewhere.
+- [x] **Stage E — every born VM is a switch participant (§3.6, G4).** 2026-09-23. Captain Bob:
+      *"yes"* (go ahead with Stage E).
+
+      Changes:
+      - `capsule_birth.c`: `capsule_birth_baby()` registers the new VM right after its task 3.2
+        common-channel subscription, at its LIVE completion point. The capsule code has already
+        run to completion by then. A full table is logged and doesn't fail the birth.
+      - `capsule_vm_switch_signal.c/.h`: `sk_vm_switch_signal_register()` is now
+        **idempotent**. An already-registered VM gets its existing slot back, not a duplicate.
+      - `kernel_main.c`: the Artemis/Hestia registrations are removed. Hera is still registered
+        there (she's the one VM never born through `capsule_birth_baby()`), together with
+        `sk_vm_switch_set_current(mama)`. Nothing can switch before that: every switch point
+        requires a current VM.
+      - `capsule_wirebind.c`: the user VM's `sk_vm_switch_signal_register()` call becomes a
+        participation lookup. `switch_slot` was only ever used as a ≥ 0 flag and is now
+        documented as one, since slot indices shift when the table compacts.
+      - The WIREBIND console VM is now a participant too. That's harmless: it never has mail,
+        so it is never chosen. It is unregistered when it's killed at detach (Stage D).
+      - Registration order changes: Hestia, then Artemis at their births, then Hera. Decisions
+        don't depend on order (C-b's walk-order evidence), but the DoE's `switch_current_slot`
+        column now numbers them in that order.
+      - Boot order checked: `sk_vm_switch_signal_boot_init()` (`kernel_main.c:536`) runs before
+        the Tripod births (`:1124`/`:1142`).
+
+      **Evidence, as named in §4.** A temporary probe, restored away from a pre-probe snapshot
+      and verified free of probe code:
+      - `register()` prints every call, and flags any `DUPLICATE`;
+      - `kernel_main.c` checks Tripod participation, then `WORKER-BIRTH`s `eprobe` **without
+        registering it by hand**, checks it is a participant, and `KILL`s it.
+
+      Probe runs with the full relay: `logs/20260923-192830/amd64/`, `-193439/aarch64/`,
+      `-194103/riscv64/`. Identical on all three:
+      - `register` lines for Hestia (count 0 → 1), Artemis (1 → 2), Hera (2 → 3), eprobe
+        (3 → 4);
+      - `STAGE-E PROBE: tripod hera=1 artemis=1 hestia=1 slots=3; WORKER-BIRTH eprobe
+        participant=1 slots=4; after KILL slots=3`, **PASS**;
+      - at WIREBIND attach, exactly **two** registrations (the console VM and `rajames~user`);
+      - **zero `DUPLICATE`** lines anywhere;
+      - the relay still gives `3`.
+
+      **Formal acceptance with the probe gone:** `logs/20260923-194803/amd64/`,
+      `-195401/aarch64/`, `-200026/riscv64/`.
+      - All reach `[zuse@Hera] ok>` with zero `UNKNOWN WORD`, failures and faults.
+      - The `dict_hash` set is unchanged.
+      - The relay gives `3` through a real switch.
+      - Idle log growth: 0 bytes.
+      - Clean build on all three plus hosted, no new warnings.
+
+      **What this makes possible (not exercised yet):** every `WORKER-BIRTH`ed DoE worker is now
+      a participant. Mail sent to a worker is delivered by a switch onto its own stack, and it
+      competes by heat. Stage G's `SEND` word and interleave test are next.

capsules/BLOCK_MAP.md

@@ -1,5 +1,5 @@
 # Capsule Block Manifest — Auto-generated
-<!-- Generated by mkcapsule --manifest  2026-09-23T23:07:10Z -->
+<!-- Generated by mkcapsule --manifest  2026-09-23T23:59:50Z -->
 <!-- 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

@@ -85,7 +85,10 @@ int sk_vm_switch_signal_boot_init(void);
  * or -1 if the slot table is full (or sk_vm_switch_signal_boot_init() was
  * never called / failed). Call once per participating VM, after that VM is
  * fully born (never mid-birth -- this stage has no critical-section
- * protection against being switched away mid-setup). */
+ * protection against being switched away mid-setup). FABRIC-3.8.md §3.6
+ * (Stage E): capsule_birth_baby() is now the one caller for every born VM
+ * (Hera, never born through it, is registered in kernel_main.c).
+ * Idempotent: registering an already-registered VM returns its slot. */
 int sk_vm_switch_signal_register(VMUuid vm_id);
 
 /* Remove a switch-signal participant (FABRIC-3.md §XXVIII Stage 4,

src/starkernel/capsule/capsule_birth.c

@@ -920,6 +920,20 @@ CapsuleRunResult capsule_birth_baby(
      * and does not fail the birth itself. */
     (void)sk_hermes_channel_subscribe(SK_HERMES_CHANNEL_COMMON, vm_id);
 
+    /* FABRIC-3.8.md §3.6 (Stage E, G4): every born VM is a switch
+     * participant -- same choke point, same "only once birth has fully
+     * completed" rule as the subscription above (its capsule code has
+     * already run to completion on the birthing VM's stack). BIRTH,
+     * WORKER-BIRTH, UNATTENDED-BIRTH and WIREBIND identities all pass
+     * through here, so none of them registers on its own any more. Soft
+     * failure, same posture: a full table leaves this VM runnable only by
+     * VM-EXEC, not a failed birth. A VM with no native stack is registered
+     * but never chosen (sk_vm_switch_decide() skips it). */
+    if (sk_vm_switch_signal_register(vm_id) < 0) {
+        log_message(LOG_WARN, "capsule_birth_baby: switch-signal table full -- %s won't be switched to",
+                    capsule_name);
+    }
+
     capsule_parity_log_birth(vm_id, cap->capsule_id, cap->content_hash, dict_hash);
 
     /* §H.12 step 11: applied AFTER dict_hash/parity logging above, not

src/starkernel/capsule/capsule_vm_switch_signal.c

@@ -143,6 +143,11 @@ int sk_vm_switch_signal_boot_init(void) {
 }
 
 int sk_vm_switch_signal_register(VMUuid vm_id) {
+    /* FABRIC-3.8.md §3.6 (Stage E): idempotent. Registration now happens
+     * once, at birth; a second call returns the existing slot rather than
+     * allocating a duplicate that the decision would walk twice. */
+    int existing = slot_for_vm_id(vm_id);
+    if (existing >= 0) return existing;
     if (g_slot_count >= g_slot_capacity) return -1;
     g_slots[g_slot_count].vm_id        = vm_id;
     g_slots[g_slot_count].parked_stamp = 0;

src/starkernel/capsule/capsule_wirebind.c

@@ -80,9 +80,11 @@ typedef struct {
     struct blkio_dev *dev;
     VMUuid            user_vm_id;
     char              username[USER_IDENTITY_USERNAME_MAX];
-    int               switch_slot; /* Stage 4: index into the switch-signal
-                                     * table, or -1 if not yet registered
-                                     * (wired in the next increment). */
+    int               switch_slot; /* Stage 4: >= 0 if the user VM is a
+                                     * switch-signal participant, -1 if not
+                                     * (table full). FABRIC-3.8.md Stage E:
+                                     * a flag, not a slot index -- indices
+                                     * shift when the table compacts. */
 } wirebind_live_entry_t;
 
 static wirebind_live_entry_t g_wirebind_live[WIREBIND_MAX_LIVE];
@@ -313,7 +315,12 @@ void capsule_wirebind_try_attach(struct blkio_dev *dev,
              * failed attach -- the identity is still fully usable via
              * ordinary VM-EXEC/console-relay dispatch, same as before
              * Stage 4 existed. */
-            live->switch_slot = sk_vm_switch_signal_register(user_id);
+            /* FABRIC-3.8.md §3.6 (Stage E): no longer registered here --
+             * capsule_birth_baby() registered the user VM (and, now, the
+             * console VM too: harmless, it never has mail, so it is never
+             * chosen) at birth. This only records whether that succeeded,
+             * which is all switch_slot has ever been used for (>= 0). */
+            live->switch_slot = sk_vm_switch_signal_is_participant(user_id) ? 0 : -1;
             memcpy(live->username, username, sizeof(live->username));
             if (live->switch_slot < 0) {
                 console_println("WIREBIND: switch-signal table full -- this identity won't be preempted");

src/starkernel/kernel_main.c

@@ -1255,8 +1255,15 @@ static void kernel_main_deep(BootInfo *boot_info) {
      * Artemis's own birth sequencing. FABRIC-3.6.md Phase 4 (Stage E),
      * 2026-09-22: Hermes's own registration here is retired along with
      * her birth above. */
+    /* FABRIC-3.8.md §3.6 (Stage E, 2026-09-23): Artemis and Hestia are no
+     * longer registered here -- capsule_birth_baby() registers every born
+     * VM at its own LIVE completion point, which they already passed. Hera
+     * is the one VM never born through it, so she is still registered
+     * here, and this is still where the switch mechanism learns she is the
+     * one running. Nothing can switch before sk_vm_switch_set_current():
+     * every switch point requires a current VM. */
     {
-        VMRegistryEntry hera_entry, artemis_entry;
+        VMRegistryEntry hera_entry;
         if (capsule_vm_registry_get(vm_uuid_hera(), &hera_entry) == 0) {
             sk_vm_switch_signal_register(hera_entry.vm_id);
             /* Seed the switch mechanism's own "who is running" tracker
@@ -1265,21 +1272,6 @@ static void kernel_main_deep(BootInfo *boot_info) {
              * ever happened. */
             sk_vm_switch_set_current(mama);
         }
-        if (capsule_vm_find_by_name_nocase("Artemis", &artemis_entry) == 0 &&
-            artemis_entry.state == VM_STATE_LIVE) {
-            sk_vm_switch_signal_register(artemis_entry.vm_id);
-        }
-        /* Hestia is the third fleet member through Phase 4 (FABRIC-3.5.md
-         * SXXXIV.4) -- FABRIC-3.6.md task 1.5, same registration shape as
-         * Artemis above, added here rather than earlier for the
-         * identical reason the comment above this block already gives. */
-        {
-            VMRegistryEntry hestia_entry;
-            if (capsule_vm_find_by_name_nocase("Hestia", &hestia_entry) == 0 &&
-                hestia_entry.state == VM_STATE_LIVE) {
-                sk_vm_switch_signal_register(hestia_entry.vm_id);
-            }
-        }
     }
 
     /* FABRIC-3.6.md task 3.2 (B1) self-test: confirm every live fleet