D5: move in, and give the assembler somewhere to look

The demo disk is three directories instead of thirty nine names in one list
with cosmos.asm sitting between fileStream.asm and sbfs.asm:

  /Apps    what you run
  /Source  what you name to the assembler
  /Lib     what those include

The split is by ROLE rather than by which directory the host keeps a file in.
Everything in /Lib is named by an #Include somewhere and by nothing else, which
is what makes it a library rather than a source.

THAT LAYOUT WAS NOT POSSIBLE UNTIL NOW, and finding out why is what this rung
actually cost. An include on the machine was a bare name resolved where you
stood, so every source that calls a service had to sit in the same directory as
services.asm - which is every source worth having. The first arrangement of
this disk put the examples in a directory of their own and none of them would
assemble.

So the native assembler has a search path: beside you, then /Lib. The same rule
the shell already uses for a program it does not recognise, applied to the
thing that reads source, and the same reasoning for it being two fixed places
rather than a list - a list needs somewhere to live between one boot and the
next, and there is no such place yet. It also brings the native assembler
nearer the host one, which has searched -I directories since before there was a
machine to run this on.

The reader's per-file state grew from 293 bytes to 301, because the name it
keeps is a path now and every block of a file is asked for by it. Six of those
would no longer fit the room set aside, so the include list moved up a page.
Both numbers are written down in two places on purpose and both were changed.

dir said cosmos.asm was 17,460 bytes. It is 82,996. The size came out of the
block count's LOW BYTE shifted up and the tail beneath it, which is sixteen
bits, so anything from 256 blocks upward came back as itself less 65,536 - a
plausible number, and wrong. Files that big say their size in blocks now.
Printing the true figure wants decimal printing twenty four bits wide, which is
a page of console.asm to say something nobody reads more precisely than "big".

The Assembler Manual's line about SBFS being flat was the last thing in the
repository still claiming it, and docs.sh now looks for that phrase and three
like it in all four documents. Not a section that is wrong - one clause inside
a paragraph that is otherwise right, which is the shape this kind of staleness
takes.

The duplicate puts are gone with the wildcard that caused them, so building the
disk is quiet.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW

Programs/CosmOS/README.md

@@ -281,6 +281,35 @@ CosmOS also boots without a disk. It reports that no filesystem was found, leave
 shell and memory monitor available, and refuses commands that require a mounted disk
 without stopping the machine.
 
+## What Is On The Disk:
+
+`make -C Programs cosmos-disk` builds the disk this system is meant to be met on, and it is
+laid out in three directories:
+
+| Where | What |
+| -- | -- |
+| `/Apps` | The programs. The second place the shell looks for a word it does not recognise, so anything here starts by name from anywhere on the disk. |
+| `/Source` | The things you name to the assembler: CosmOS itself, the assembler itself, and small programs to read. |
+| `/Lib` | The things those include. Everything here is named by an `#Include` somewhere and by nothing else, which is what makes it a library rather than a source. |
+
+The split is by role rather than by which directory the host keeps a file in, and it only
+works because **an include is looked for where you are and then in `/Lib`** - the same rule
+the shell uses for programs, applied to the assembler. Without that search every source
+that calls a service would have to sit beside `services.asm`, and there would be nothing to
+organise.
+
+So the machine rebuilds itself from its own disk:
+
+```text
+> cd /Source
+/Source> Asm cosmos.asm
+wrote cosmos.bin: program 9778, data 3346, labels 648
+/Source> Asm Asm.asm
+wrote Asm.sbx: program 7570, data 4114, labels 562
+```
+
+Both come out byte for byte what the host assembler makes from the same source.
+
 ## Included Applications:
 
 `Programs/CosmOS/Apps` holds what the shell can load, and the application disk is built