Expand each run_magic*.sh header to state its purpose, usage, and the full set
of environment overrides. Initialize every knob with ${VAR:-default} so a value
inherited from the environment always wins:
- CAD_ROOT is now overridable (was hardwired to $builddir/CAD_DIR); point it at
a shared/installed tree to skip staging.
- WISH/TCLSH default to the wish/tclsh configure detected for this build's
Tcl/Tk (@WISH_EXE@/@TCLSH_EXE@, matching --with-tk/--with-tcl), so a build
against a non-standard Tcl/Tk automatically uses the correct absolute paths.
MAGIC_WISH (what tkcon.tcl uses for the Tk console) defaults from WISH.
Add magic_check_env(): on source, sanity-check each value (directory / regular
file / executable, as appropriate) and print a non-fatal stderr warning naming
the offending variable and whether it came from the environment or the baked
default -- to make a bad override easy to diagnose. Empty optional values
(e.g. no tclsh configured) and a not-yet-created CAD_ROOT are not flagged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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