feat: better way to pass git rev

.gitignore

@@ -1 +1,2 @@
 result*
+*.pdf

.rev

@@ -1 +0,0 @@
-UNSTABLE_DO_NOT_USE

flake.nix

@@ -54,11 +54,11 @@
               dest = "icons";
               src = "${inputs.font-awesome}/svgs/regular";
             }
-            {
-              src = ./.rev;
-              dest = ".rev";
-            }
           ];
+
+          typstOpts = {
+            input = ''GIT_REV=${if (self ? rev) then self.rev else "GIT_UNSTABLE_DONT_USE"}'';
+          };
         };
 
         typstPackagesSrc = "${inputs.typst-packages}/packages";
@@ -83,14 +83,6 @@
             XDG_CACHE_HOME = typstPackagesCache;
 
             SOURCE_DATE_EPOCH = builtins.toString self.lastModified;
-
-            preBuild =
-              if (self ? rev) then
-                ''
-                  echo ${self.rev} >> .rev
-                ''
-              else
-                "";
           }
         );
 

template.typ

@@ -1,6 +1,6 @@
 #import "@preview/fontawesome:0.5.0": *
 
-#let git_rev = read("./.rev", encoding: "utf8")
+#let git_rev = sys.inputs.GIT_REV;
 
 #let _cv-line(left, right, ..args) = {
   set block(below: 0pt)
@@ -147,7 +147,7 @@
     #name\
     #datetime.today().display("[month repr:long] [day], [year]")
 
-    #text(size: 8pt)[Built from revision #git_rev]
+    #text(size: 8pt)[Built from revision #git_rev.]
   ]
 ]