feat(v4.0.0): messages are whole and wait on the wire -- a node keeps none but the one it is doing

Step 6e, tasks 2 and 3 (docs/v4.0.0/MESH.md 7d).  The nucleus puts, looks
at, takes, moves and drops whole messages through the six addresses after
its ports; its own ring of messages waiting, the refusals owed, (GATE) and
the looking words' use are gone.  SEND, an answer, a NACK and a GONE go or
are refused at once; what a text prints waits for room; a text is not
begun until the wire its answer goes by has room for it, and that room is
kept.  The lone node's host (v4/system/boot.c) keeps its two wires and
does its operations; the test hosts' consoles put and take whole messages
through the fabric.  New: tests/test_host_depth.c, every message path of
a mesh node at every depth of both stacks.

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

v4/include/v4/boot.h

@@ -71,8 +71,8 @@ typedef struct {
 int v4_boot_run(const v4_boot *b);
 
 /* Hand the node a line and run it to its end, sending what it prints to
- * `out`.  The line is sent to the node as a message and what it prints
- * comes back as messages (message.h).  Returns how it ended -- V4_TEXT_QUIT,
+ * `out`.  The line is put on the node's wire as a message, whole, and what
+ * it prints comes back as messages (message.h; docs/v4.0.0/MESH.md 7d.5).  Returns how it ended -- V4_TEXT_QUIT,
  * V4_TEXT_COMPLETED or V4_TEXT_ERROR -- or one of these: */
 #define V4_BOOT_LINE_TOO_LONG (-1)       /* more than the node's input buffer holds; nothing was run */
 #define V4_BOOT_LINE_STOPPED  (-2)       /* the node stopped on a fault, or never finished */
@@ -81,12 +81,12 @@ int v4_boot_run(const v4_boot *b);
 int v4_boot_line(const v4_boot *b, const char *text, unsigned len);
 
 /* A LINE THAT WAITS (docs/v4.0.0/MESH.md 7b.6).  V4_BOOT_LINE_WAITING means
- * the line has not ended: the node is waiting at its ports for an answer,
+ * the line has not ended: the node is asleep, waiting for an answer,
  * and here there is no one but the console to end that.  The host reads the
  * next line and hands it over as usual: that breaks the wait, and what is
  * returned is how the line that was waiting ended -- in an error,
- * Interrupted.  The node has kept the line just handed over; the host then
- * calls v4_boot_line with no text (0, 0) to have it done, and that returns
+ * Interrupted.  The line just handed over is still on the node's wire; the host
+ * then calls v4_boot_line with no text (0, 0) to have it done, and that returns
  * how it ended, which may be V4_BOOT_LINE_WAITING again. */
 
 /* The dictionary hash of a node started from `im`. */

v4/include/v4/image.h

@@ -27,8 +27,8 @@ typedef struct {
     unsigned cell_bits, node_words, data_ring, ret_ring;
 
     /* Where the nucleus waits for a message (v4/capsule/quit.v4, (IDLE)):
-     * the node's P is there, blocked reading its ports, when it has nothing
-     * to do. */
+     * a node that has taken the nucleus in begins there, and with nothing
+     * to do it is asleep at a wire inside it (operation 8, MESH.md 7d.3). */
     v4_cell idle;
     v4_cell fault_table;                 /* (FAULTS): where a fault goes */
     v4_cell port;                        /* word address of the node's port (node.h) */