feat(v4.0.0): five nodes from nothing -- Hera asks for nodes, births and joins them

MESH.md step 5, in the fabric under test; the products are still one
node each until steps 8 and 9.

manage.c: what Hera asks of whoever holds the fabric, eleven requests by
KERNEL-WORD -- NODE-ME -BORN -WIRE -UNWIRE -SLEEP -WAKE -KILL -PARITY and
CAPSULE-OPEN -CELL -LINE. Nucleus: PORT!, SEND-ON, AWAIT, (SEAL).
capsules/v4/hera.4th: BIRTH and UNIT, the unit rule in FORTH and nowhere
else. The dictionary hash moves to the engine (v4_image_dict_hash).

test_host_unit.c, 34 checks, 64-bit: Hera is born empty, takes the
nucleus through her port, FORTH-79, POST and her capsule; 10 UNIT; four
nodes are born, each takes the nucleus and FORTH-79 through its port from
Hera and passes POST 538/538; four parities, one dictionary hash; they
talk, and a message between two corners not wired goes by Hera.

All v4 tests at both widths and under ASan+UBSan. hosted-check on three
ISAs. Bare metal: logs/20261006-143934 (amd64), -144204 (aarch64),
-144601 (riscv64).

Open, recorded in MESH.md: not run at 32 bits; a node that never answers
leaves Hera waiting; the capsules are read from files in the test, not
from the baked directory.

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

v4/capsule/core.v4

@@ -181,13 +181,18 @@ header CMOVE
   SET: (MQ-HEAD) a! !
   (MQ#) a! @  -1 +  ! ;
 
-\ ( port to -- )   take in a message.  B is at the port, by its address,
-\ and `to` is the message's first word, already read from it.  A length
+\ ( port to -- )   the seven words of a message being taken in, and the
+\ port, go into (MQ-HDR).  B is at the port, by its address, and `to` is
+\ the message's first word, already read from it.
+: (TAKE-HDR)
+  (MQ-HDR) a! !+  5 FOR @b !+ UNEXT  ! ;
+
+\ ( -- )   the message whose seven words are in (MQ-HDR) is kept with the
+\ messages waiting: its text is read from the port B is at.  A length
 \ below zero, or above what a message carries, is kept as -1 with no text:
 \ a longer one is read to its end first, so that what follows it is not
 \ taken for a message.
-: (TAKE)
-  (MQ-HDR) a! !+  5 FOR @b !+ UNEXT  !                                \ its seven words, and the port
+: (TAKE-KEEP)
   (MQ-HDR)+6 a! @  -if SIZED
   drop  -1 (MQ-HDR)+6 a! !  0  jump COUNTED
   SIZED: dup -1025 + -if LONG  drop  3 + 2/ 2/  jump COUNTED
@@ -203,6 +208,9 @@ header CMOVE
   GONE: drop
   LOSE: (LOST) a! @  1 +  ! ;
 
+\ ( port to -- )   take in a message and keep it
+: (TAKE)   (TAKE-HDR)  jump (TAKE-KEEP)
+
 \ ( port -- )   wait until a message may be begun on the port, by its
 \ address, taking in whatever is being written to this node meanwhile; and
 \ leave B at the port.  The port is kept in (GATE-PORT), not on the stack:

v4/capsule/quit.v4

@@ -175,13 +175,11 @@ header DEFAULT-ROUTE
 header NO-ROUTES
 : NO-ROUTES   0 (ROUTE#) a! !  0 (ROUTE-DEFAULT) a! ! ;
 
-\ ( baddr u node -- )   send the node u characters of text to interpret.  It
-\ is on its way when SEND returns; what it prints there goes to that node's
-\ console.  With no way to the node it is error 12.  The write waits for the
-\ neighbour to read, and is not begun until it may be (core.v4, (GATE)).
-header SEND
-: SEND
-  dup (PORT-FOR) if NOWAY
+\ ( baddr u node port -- )   send the node u characters of text to
+\ interpret, by the port given, by its address.  It is on its way when this
+\ returns.  The write waits for the neighbour to read, and is not begun
+\ until it may be (core.v4, (GATE)).
+: (SEND-ON)
   (GATE)  !b                                 \ to
   1 (HDR)
   dup !b                                     \ length
@@ -189,8 +187,59 @@ header SEND
   FOR  dup C@  over 1 + C@ 8* +  over 2 + C@ 8* 8* +  over 3 + C@ 8* 8* 8* +  !b  4 +  NEXT
   drop ;
   NONE: drop drop ;
+
+\ ( baddr u node -- )   send the node u characters of text to interpret,
+\ by the way this node knows to it.  What it prints there goes to that
+\ node's console.  With no way to the node it is error 12.
+header SEND
+: SEND
+  dup (PORT-FOR) if NOWAY  jump (SEND-ON)
   NOWAY: drop drop drop drop  NODE-ERROR b! 12 !b ;
 
+\ ( baddr u node port -- )   the same by a port this node names, by its
+\ number, whatever ways it knows: for a neighbour that has no number of
+\ its own yet, to which text is sent as to node 0.
+header SEND-ON
+: SEND-ON
+  dup -if POS  jump BAD
+  POS: -PORTS + -if BAD  drop  (PORT) +  jump (SEND-ON)
+  BAD: drop drop drop drop drop  NODE-ERROR b! 12 !b ;
+
+\ ( node -- how )   WAIT FOR THE NODE'S WORD OF HOW TEXT ENDED: 0 QUIT,
+\ 1 completed, 2 an error.  This node is blocked reading its ports until a
+\ message of type 3 comes for it from that node; every other message that
+\ comes meanwhile is kept with the messages waiting.  It waits for ever
+\ for a node that never answers.
+header AWAIT
+: AWAIT
+  (AWAIT-FROM) a! !
+  L: (PORT)+8 b! @b  (PORT)+9 b! @b  (PORT) +  dup b!  SWAP  (TAKE-HDR)
+  (MQ-HDR) a! @  (ME) a! @  xor if A1  drop jump KEEP
+  A1: drop  (MQ-HDR)+2 a! @  -3 + if A2  drop jump KEEP
+  A2: drop  (MQ-HDR)+1 a! @  (AWAIT-FROM) a! @  xor if A3  drop jump KEEP
+  A3: drop  (MQ-HDR)+6 a! @  -4 + if A4  drop jump KEEP
+  A4: drop  @b ;                                                      \ its one word
+  KEEP: (TAKE-KEEP)  jump L
+
+\ ( w port -- )   write a cell to the port, by its number.  It waits until
+\ the neighbour has taken it.  This is how a node is sent a capsule of F18
+\ code (docs/v4.0.0/MESH.md section 5): the cells go as they are, not as a
+\ message, to a node that is executing from its ports.
+header PORT!
+: PORT!
+  dup -if POS  jump BAD
+  POS: -PORTS + -if BAD  drop  (PORT) + b!  !b ;
+  BAD: drop drop drop  NODE-ERROR b! 12 !b ;
+
+\ ( -- )   WHAT IS IN THE DICTIONARY NOW IS THE SYSTEM: COLD comes back to
+\ it and FORGET will not go below it.  Whoever has loaded a node's capsules
+\ has it do this (system.v4, (BOOT) and FENCE).
+header (SEAL)
+: (SEAL)
+  DP a! @  (BOOT) a! !
+  (LATEST) a! @  (BOOT)+1 a! !
+  DP a! @  3 +  2/ 2/  FENCE a! ! ;
+
 \ FORTH-79: clear the return stack, set execution mode, return control to
 \ the terminal; no message is given.  The data stack is left as it is.
 \ NODE-ERROR, by name: how a definition written in FORTH raises an error.