LithosAnanake/docs/v4.0.0/MESH.md

StarForth v4.0.0 — Talking nodes

Design, 2026-10-06. Ruled by Captain Bob by question and answer on 2026-10-05 and -06; each ruling is recorded with his words in ENGINE.md section 3d. This file is the design that follows from them. Where it goes beyond a ruling it says so, and those parts are proposals.

1. What this step is

The entire point is that ultimately we have F18 engines digesting capsules alone, and in a sense can be anything written in F18 assembler for our fabric — 144 someday as a 12x12 grid, but I want a 12^3 FPGA ultimately, where using a capsule digester like StarForth, it's more than an operating system.

The next step is talking nodes sharing the common SSD, and [they] may or may not have block storage available.

More than one node, each born empty and made into something by the capsule it takes in, talking to each other through ports, sharing a disk. It comes before making v4 equal v3 on bare metal (ENGINE.md step 4), which waits.

2. The rulings

1. The ports are the transport; the message is what is transported. Node to node, a write blocks until the neighbour reads and a read blocks until the neighbour writes (DECOMPOSITION.md section 6). What travels is v3's Hermes message with what it carries, so v3's messaging rules are not dropped: they go with the message.
2. Some nodes have storage of their own, in addition to or instead of the common SSD. Some have none.
3. The first set of nodes is "2x2 + 1 central": five.
4. The geometry is data, not design. A node has a number of ports, and that number is a parameter. Which port connects to what is a table that can change while the system runs. "Not constrained by a 3D world. Other geometries might be better."
5. The first geometry: "Only the central node can connect to only another central node." Four outer nodes and their centre are a unit. An outer node is wired only inside its unit. Units are joined centre to centre.
6. It must scale at run time, adaptively.
7. Hera decides which nodes exist and are awake, not whose turn it is. Every node that is not blocked runs. Cooperative is a node blocking itself at a port; preemptive is Hera putting a node to sleep or killing it between any two instruction words. An idle node does not spin: it is blocked reading its ports.
8. A node is born empty. It has nothing but the ability to listen. The first thing a neighbour sends it is a capsule of F18 code. StarForth's nucleus is such a capsule.
9. Built in the shared engine, proven hosted on three ISAs first, then on bare metal.

3. Acceptance (approved 2026-10-06)

1. Five nodes come up from nothing. Hera is born empty, takes in the nucleus capsule and the FORTH-79 capsule, and passes POST. She births the four outer nodes while running; each is born empty, takes in the same capsules through its port from Hera, and passes POST. Each prints a parity line; the four outer nodes' dictionary hashes are identical.
2. They talk. A line typed at the console reaches Hera as a message. A message from Hera runs on an outer node and its output comes back. A message between two outer nodes that are not wired to each other is forwarded by a node in between.
3. They share the SSD. A block written by one node is read by another. One outer node has a drive of its own and uses it. One has no storage, and BLOCK on it is an error with a message.
4. It scales while running. A second unit of five is born and joined centre to centre. A message crosses from one unit to the other. The second unit is removed and the first carries on.
5. Hera manages. An idle node executes nothing while it waits, which the anti-clock shows. Hera puts a node to sleep and wakes it. Hera kills a node that is stuck in an endless loop, and everything else keeps running.
6. On every build. The three hosted ISAs, then the three bare-metal ISAs under QEMU with the real console and disk.

Left for the step after, by agreement:

• Hera sleeping, waking and killing nodes by herself from each node's heat. Here she does it by command. The rule for it has not been given.
• v3's messaging rules checked at every hop. From this step a message carries its heat, TTL and ACL tag; checking them is the router's, and the checks await rulings.

4. The engine: ports

Everything in this section is the engine's (v4/src) and knows nothing of StarForth or of any kernel.

4.1 A node's ports

A node has V4_PORTS ports. The number is a build parameter, as V4_CELL_BITS and V4_NODE_WORDS are. (Proposal: 8 for now, which is what the first geometry needs of a centre — four outer nodes, two devices, two other centres — with nothing depending on the number.)

Ports are addresses, as DECOMPOSITION.md section 6 has them. Attached at word address base:

Address	What
base … base + V4_PORTS − 1	Port 0 … port V4_PORTS − 1
base + V4_PORTS	Any port: a read here takes from whichever port has a neighbour writing
base + V4_PORTS + 1	Which port the last read from "any" came from. Read only.

• A write to a port blocks the node until the neighbour has read it. Built 2026-10-05 for one port; the opcode after the write runs when the write has been taken.
• A read from a port blocks the node until the neighbour writes. The fetch does not happen until there is something to fetch. This is new.
• A read is any fetch: @, @b, @+, the literal fetch @p, and the fetch of an instruction word when P is a port address. When P is a port, it is not advanced: the node goes on executing what arrives there. That is how an F18 node runs code from a port, and it is what makes ruling 8 need no code in a newborn node.
• A port with nothing on the other end blocks for ever, as on the fabric.

4.2 A node at reset

P is the "any port" address, both stacks are empty, memory is zero. The node is blocked reading its ports. Nothing else is in it.

4.3 The fabric

v4/src/fabric.c: the nodes there are, how their ports are wired, and time passing for all of them at once.

• The nodes. A set that grows and shrinks while the system runs (ruling 6). A node is added empty (4.2) and removed whole.
• The wiring. For each port of each node: nothing, or a port of another node, or a device. It is a table, changed at run time (ruling 4). The fabric does not know what shape it makes.
• A device is what is on the other end of a port that is not a node: two functions, one that takes a word the node writes and one that gives a word when the node reads, each able to say "not yet". The console, a disk, and the kernel that serves a node's requests (ENGINE.md 3.3) are devices.
• A step. Every node that is awake and not blocked executes one instruction word. Then every write that has a reader waiting on the other end of its wire is handed over, and both nodes are unblocked. That is all: there is no choice of whose turn it is (ruling 7).
• Asleep. A node that is asleep executes nothing and nothing is handed to it or taken from it. It is put to sleep and woken from outside, at any instruction word.

4.4 What is not in the engine

Messages, routing, capsules, the unit of five, Hera. Those are sections 5 to 8 and are made of capsule code and of the host that owns the devices.

5. A capsule of F18 code, and how an empty node takes it in

As built. A capsule of F18 code is not a format a node has to understand. It is the words a neighbour writes to the node's port, in the order they are written: for each stretch of memory that is not zero the two instruction words below with their address and count and then the words themselves, and at the end a jump to where to start. The file is those words, each in a cell's bytes, low byte first, and its hash is the hash of exactly what is sent. The nucleus is one, in the capsule directory with a name, a hash and a signature like any other. mkcapsule was not changed: the nucleus capsule is a built file kept under capsules/v4/.

A neighbour puts it into an empty node by writing to the port between them, and the node executes what arrives (4.1). For each run it sends

@p a! @p push       \ then the address, then count − 1: executed from the port
@p !+ unext         \ then the words: each is fetched from the port and stored

and at the end jump to the start address. That is the F18's own way, and it needs nothing in the node beforehand.

6. A message

Proposal, from DECOMPOSITION.md section 6.1 and v3's SkHermesMessage (kernel/include/starkernel/vm/kernel_hermes.h), which it must be able to carry whole:

Word	Contents
0	To: the node it is for
1	From: the node that sent it
2	Type, and the channel
3	Heat and TTL
4	ACL tag: the sender's identity fingerprint
5	Sequence
6	Payload length in characters, 0 to 1024
7 …	Payload: FORTH text, four characters to a word

It is written to a port a word at a time and read a word at a time. Words 3 and 4 are carried from this step on and are not yet checked (section 3).

A node that is a StarForth digester, when it has nothing to do, reads a message from "any port". If it is for this node, the payload is interpreted, as a line is today (ENGINE.md 3.1). If it is for another, it is written to the port that leads there (section 7).

What a node prints goes to its console, and its console is a place like any other: for the node wired to the console device, that port; for any other node, a message to the node that is. So what an outer node prints comes back through its centre.

7. Finding the way

Proposal. Each node has a small table: for a destination, the port that leads toward it; and one port for everything not in the table. Whoever wires a node writes its table, and changes it when the wiring changes. Under the first geometry an outer node's table is its two grid neighbours and "everything else to my centre"; a centre's is its four outer nodes, and for each other unit the port toward that unit's centre.

A different geometry is a different way of filling in the wiring table and these tables. Nothing else changes.

8. Storage

Proposal. A disk is a device on a port. Asking for a block is a message to it — read block n, or write block n with 1024 characters — and the answer is a message back; a block is exactly the most a message carries. Under v3's one block-number space, each device has its own range of numbers.

• A node wired to a disk asks it directly.
• A node not wired to one asks through the node that is: the message is forwarded like any other. So the common SSD is shared by every node that has a way to the node that holds it.
• A node with its own drive has that device on one of its own ports.
• A node with no way to any disk has no storage, and BLOCK says so.

Who may have which block is the block card's, decided where the disk is, under the identity in the message's ACL tag (V3-PARITY.md 1d). Not checked in this step.

9. Birth, and Hera

Proposal. Hera asks, through the port where her requests go (ENGINE.md 3.3), for a node to be added and wired; she then sends the newborn its capsules through the port that joins them. Putting a node to sleep, waking it, and removing it are requests of the same kind. Only Hera's requests are honoured.

The unit rule (ruling 5) is Hera's, in capsule code: it is what she does with those requests. The engine and the host do not know it.

10. Steps

Each is tested, committed and pushed before the next.

1. Ports and the fabric (section 4). Reads; "any port"; a node at reset; execution from a port; nodes added and removed; wiring changed; asleep and awake. Tests at the level of opcodes: two nodes exchange words; an empty node is filled through its port and runs what it was sent; a word is passed on by a node in between; a node waiting executes nothing; a node is put to sleep, woken, and removed while looping. Done 2026-10-06. v4/src/node.c (the ports, v4_node_born), v4/src/exec.c (a fetch from a port waits; execution from a port; the slot a blocked node goes on from), v4/src/fabric.c. V4_PORTS is 8. v4/tests/test_fabric.c, 53 checks at both cell widths and under ASan and UBSan: all of the above, with the empty node filled once by a device and once by another node holding the capsule in its own memory; the fabric given more room while nodes run; what cannot be wired refused. The single-node products are unchanged by it: hosted-check on three ISAs, and the three bare-metal boots with lines typed at each prompt (logs/20261006-074907, -075150, -075532).
2. The nucleus as a capsule, and an empty node made a StarForth node through its port (section 5). Done 2026-10-06. v4/src/capsule.c, v4_capsule_write: any node's memory as the words to send an empty node. mkimage writes the nucleus so, to capsules/v4/nucleus-64.f18, a built file kept in the tree as BLOCK_MAP.md is; mkcapsule is unchanged and bakes, hashes and signs it with the rest. The boot's node is born empty (v4_image_born) and is given the nucleus a word at a time as it reads its port, after the capsule's hash and signature are checked (v4/system/boot.c). Nothing of the nucleus is linked into either product any more. test_fabric.c: a memory with a programme and words here and there arrives word for word and runs. Both products boot so: hosted-check on three ISAs; logs/20261006-102421, -102706, -103048. What a newborn node still has from its host: the registers the nucleus expects — the console's three, the two stack registers, the error register, the fault table's address, the storage registers — are attached by the host when the node is born, from the description mkimage writes. They are the node's hardware as the golden model has it, at addresses the memory map (D-4, still open) will fix. The console and storage ones go when those become devices on ports (steps 3 and 6).
3. Messages (section 6): a StarForth node that reads messages when idle; the console as a device; a line typed is a message. Done 2026-10-06, but for the keyboard. A node with nothing to do is blocked reading "any port" ((IDLE), v4/capsule/quit.v4). What arrives is a message; text for this node is interpreted; what it prints is kept and sent back as messages to the sender, on the port the message came on, and then a message saying how the text ended (EMIT, (FLUSH-OUT), (HDR) in core.v4; (FINISH) in quit.v4). v4/src/message.c is the same format for whatever is on the other end of a port and is not a node. The boot is that, on the node's port 1, as the console (v4_boot_line); the prompt tests are too. Handing a node a line by writing its input buffer and setting its P is gone (v4_line_begin and the rest). Nothing reads the CONSOLE-TX register any more. EMIT still needs one free cell of the data stack and no more, as before; it keeps its working values on the return stack. The full-stack tests hold at the same figures as before. All v4 tests pass at both widths and under ASan and UBSan; hosted-check on three ISAs; bare metal logs/20261006-110551 (amd64), -111621 (aarch64), -111341 (riscv64). -110837 is an aarch64 run that was ended by the test wrapper's limit while still in UEFI firmware, before the kernel had started; it shows nothing about v4. Not done: KEY, EXPECT and QUERY still read the console's two input registers, not a message. A message not for this node, or not text, is let go: passing it on is step 4.
4. Finding the way (section 7).
5. Birth and Hera's requests (section 9); the unit of five.
6. Storage (section 8).
7. A second unit; scaling while running; sleep, wake and kill by command.
8. The hosted product is the five nodes, on three ISAs: acceptance 1 to 5.
9. The same on bare metal: acceptance 6.

11. What becomes of what is there

• v4/system/boot.c and v4/tools/hosted.c hand one node a line and run it to the end. They stay until step 8, where the hosted product becomes the five nodes.
• (LINE) and (IDLE) (v4/capsule/quit.v4): (LINE) stays, as what interprets a message's payload. (IDLE) becomes the read of a message at step 3.
• The one port of 2026-10-05, where a node's requests go, is port 0 of the ports of 4.1.
• The nucleus linked into the binary goes at step 2.
• DECOMPOSITION.md section 6 says four ports; it is corrected at step 1.