Tab reaches the disk

Paths and programs, which is the half that makes it worth having. The first word
of a line is a command or a PROGRAM, offered under the name somebody would type
- the extension taken off - and anything after it is a file, offered as it
really is. A separator anywhere in the word says which directory to look in.

A directory answers with a separator on the end instead of a space, which says
what it is and lets the next part be typed straight away. The answer ending in
one is also what stops a space being added, so that is one test rather than a
flag.

PROGRAMS ARE LOOKED FOR WHERE THE SHELL WOULD LOOK to run one: where you are,
/Apps on the disk you are on, and /Apps on drive 0. Offering something the shell
would not find would be finishing a word into a thing that then does not work.
Drive 0's is skipped when that is already the drive, or every program in it
would be offered twice and nothing would ever be the only match.

Walking somebody else's directory means standing in it, which is the only way to
walk one here, so where the person was and which drive they were on are put down
first and restored whatever happens.

Three bugs, all found by running it:

THE DIRECTORY TEST WAS INVERTED. dir asks the same question the same way round
four hundred lines further up, which is what made it obvious once looked at.

THE /Apps WALK OVERWROTE THE TYPED PATH. The whole search runs a second time to
list the matches, and by then TabDir said "/Apps" - so a word that had named
nowhere went looking in the wrong place and listed nothing at all. Two ways into
the walk now, and the typed path is never written over.

AND LISTING ONLY KNEW ABOUT COMMANDS, because it was a second copy of the walk.
It is the same walk with a flag now: finding the answer and showing the matches
are the same question asked twice.

Also cosmosMonitor, which had been RE-BLESSED INTO MEANINGLESSNESS by the wall
move. It disassembles a loaded program, at an address the input names - and that
address moved a page while the recording was simply re-recorded to whatever came
out, which was a page of zeroes. It is pointed at 5000 again.

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

Tests/expected/cosmosTab.out

@@ -10,24 +10,10 @@ dir  do  drive  delete
 I do not know: d
 > zzzx
 I do not know: zzzx
-> echo here
-here
-> help  help 
-dir          list what is on the disk
-load <file>  read a program off the disk
-run [words]  start what was loaded, and tell it those words
-<name> [words]       look where you are and then in /Apps, and start that
-cd [path]    go to a directory, or to the root with nothing after it
-mkdir <path>         make a directory
-rmdir <path>         remove an empty one
-do <file>    run the lines in a file, which must start with #!
-echo [words] say them
-clear        empty the screen
-delete <file>        take it off the disk
-rename <file> <to>   call it something else
-monitor      look at memory, change it, and jump into it
-help         this
-exit         stop, or leave the monitor if you are in it
+> echo heecho hello.sbx re
+hello.sbx re
+> help  hel
+I do not know: hel
 > exit
 halted
 Execution halted.