THE TRIANGLE
============

The unit of a Triangle Tree. One triangle = one node = one component.


THREE CORNERS
-------------

        G           G = Goal      what this node is for
       / \          S = Sensor    what comes in from the world
      S---A         A = Actuator  what goes out to the world


SIX FIELDS
----------

Every triangle holds six fields: the three corners, and three
behaviours that run between them.

              G  goal
             / \
            /   \
     plan  /     \  navigate
          /       \
         S---------A
      sensor   |    actuator
             control

    goal       the target state, written in quarks
    sensor     the channels this node reads
    actuator   the forces or data this node puts out
    control    reflex: sensor -> actuator, without deliberation
    plan       sequencing toward the goal
    navigate   choosing a mode, a branch, a place to be

The corner mapping is canonical. Putting control/plan/navigate on
the edges is a reading, not a rule -- it is just where each one sits
between the corners it connects.


FILLED IN
---------

From drone.json, the radar node:

    name       radar
    goal       data pattern obstacle
    sensor     radiation pattern loc
    actuator   -
    control    stat near -> alert computer
    plan       pattern
    navigate   waitfor event


FIRING
------

A control field with '->' is a rule. Left of the arrow is a quark
condition, right of it an action:

    stat near      -> alert computer
    stat stall     -> stop
    stat overload  -> stop pulley

A control field without '->' is not a rule but a declaration of the
quarks this node's control domain works in:

    conflict val normal

The quarks on the left never carry units or numbers. Those live in
the grounding rules in log.csv, which turn a measured channel into a
quark:

    cable tension beyond safe working load
        i;gt;cable_tension_kn;kN;stat overload;8;25;

So log.csv says 25 kN is overload; the triangle says overload means
stop. Recalibrate the machine without touching the model.


HOMEOSTASIS
-----------

A triangle does not run once. It runs continually, closing the gap
between goal and actual:

    world --measure--> grounding --quark--> control
      ^                                        |
      |                                        act
      +---------------- effect ----------------+

While the reading sits inside the normal band, nothing fires. A
deviation fires a rule, the action pushes back, the reading returns
to the band. That return is homeostasis.


TREES AND TILES
---------------

Triangles compose. A parent's children elaborate it -- the root is
the whole system, its children are assemblies, their children are
components:

                    /\
                   /  \  root
                  /____\
                 /      \
                /        \
              /\          /\
             /  \        /  \   assemblies
            /____\      /____\
            /    \      /    \
          /\      /\  /\      /\
         /  \    /  \/  \    /  \  components
        /____\  /____\____\  /____\

Any subtree lifts out whole and stays valid on its own. That is a
tile. Tiles compose into a larger model.