A program can ask where it came from

SWI osWhereAmI hands back the path the program was loaded from, on the
same terms as osArgument, and Libraries/path.asm joins a name to the
place another thing is in. Between them an application can find its own
assets: ask where you are, then pathBeside that and the file's name.

The answer FOLLOWS THE PROGRAM AND NOT THE PERSON, which is the whole
point and the reason the working directory could not serve. A program's
assets are relative to the program and its arguments are relative to
whoever ran it, and cwd can only be one of them - setting it to the
program's own would mean "Play mytune.tune", typed by somebody in their
own directory, looked in Play's.

It is made absolute before the program starts, because the path the
search settled on may be a bare name: a program found where somebody was
standing is named by the word that was typed, and a bare name means the
working directory - which a program is entitled to move out of. Worked
out once, at the start, since where a program came from is a fact about
its start and cannot change afterwards.

Joining is a LIBRARY and not a service. A service that opened a file
relative to the program would need a twin for every file operation there
is - read, save, info, block, start, write, done, delete, rename - while
one service handing back a path composes with all of them.

---- And the root's own path was "//" ----

Found by the first caller that asks. shellPath prepends a separator in
front of whatever string it is given, so being handed the separator
itself wrote two of them. Nothing saw it while the only caller was the
prompt, which asks where it is only when that is not the root. It is
handed an empty string now, and cosmosWhere runs a program from the root.

Where.sbx exists to be run rather than read, and is on the test disk
twice: at the root, where it is found by the bare word typed, and in
/Apps, where it is found by a path that already says where it is.

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

Programs/CosmOS/Source/services.asm

@@ -185,3 +185,26 @@
 ; NOT AUTOMATIC, and that is the point: dir and Say print and stop, and their output is the
 ; reason you ran them. Only a program that says it took the screen gets the screen put back.
   osTakeScreen   0d36
+
+; ---- Where the program itself came from ----
+;
+; DP0 says where to put it and B is how much room there is counting the zero, the same
+; bargain osArgument offers. What comes back is the whole path the program was loaded from,
+; made absolute: a program found where somebody was standing is named by the bare word that
+; was typed, and a bare name means the working directory - which a program is entitled to
+; move out of.
+;
+; ---- Why this and not "open a file beside me" ----
+;
+; A service that opened a file relative to the program would need a TWIN FOR EVERY FILE
+; OPERATION there is: read, save, info, block, start, write, done, delete, rename. One
+; service handing back a path composes with all of them, and joining a name to a place is
+; then a library rather than a service - Libraries/path.asm, beside print.asm and math.asm.
+;
+; ---- And why not just move the program there ----
+;
+; Because a program's ASSETS are relative to the program and its ARGUMENTS are relative to
+; the person, and the working directory can only be one of them. Setting it to the program's
+; own would mean "Play mytune.tune", typed by somebody in their own directory, looked in
+; Play's. The working directory stays the person's; this is how a program finds its own.
+  osWhereAmI     0d37