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

Tests/manifest

@@ -1000,6 +1000,23 @@ cosmosScriptNest     | CosmOS/Source/cosmos.asm           | run      | cosmosScr
 # which would let a command run with an argument missing. At the prompt they are ordinary
 # unset names, because there is no script to have been given anything.
 cosmosScriptArgs     | CosmOS/Source/cosmos.asm           | run      | cosmosScriptArgs.in | 200000000 | disks/cosmos.img
+# ---- Where a program came from ----
+#
+# osWhereAmI and Libraries/path.asm, which are what an application with assets stands on.
+#
+# THE ANSWER FOLLOWS THE PROGRAM AND NOT THE PERSON, which is the claim 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. Standing in /work, the copy in /Apps says /Apps
+# and puts its asset there, while the argument still means what the person typed.
+#
+# Two copies of it on this disk reach the system by different routes. The one at the root is
+# found where you are standing and named by the bare word typed, so the path has to be worked
+# out from where the person was; the one in /Apps arrives already absolute. Running it from
+# the root is also the check on the root's own path, which came out as "//" until the first
+# caller that asks there rather than only when somebody has moved.
+#
+# And load then run, because that is the other way into the same place.
+cosmosWhere          | CosmOS/Source/cosmos.asm           | run      | cosmosWhere.in     | 200000000 | disks/cosmos.img
 # ---- Starting itself ----
 #
 # /System/Boot/startup.sh runs before anybody can type. This one is also the check on #quiet