diff --git a/README.md b/README.md
index 4cd8317..1a4729d 100644
--- a/README.md
+++ b/README.md
@@ -66,7 +66,7 @@ The following goes recursively through `./modules` and imports all `.nix` files.
 
 For more advanced usage, `import-tree` can be configured via its extensible API.
 
-______________________________________________________________________
+---
 
 #### Obtaining the API
 
@@ -228,7 +228,7 @@ Returns a fresh import-tree with empty state.
 
 ##### 🌳 `import-tree.initFilter`
 
-*Replaces* the initial filter which defaults to: Include files with `.nix` suffix and not having `/_` infix.
+_Replaces_ the initial filter which defaults to: Include files with `.nix` suffix and not having `/_` infix.
 
 ```nix
 import-tree.initFilter (p: lib.hasSuffix ".nix" p && !lib.hasInfix "/ignored/" p)
@@ -257,7 +257,7 @@ Exactly the same as calling the import-tree object with an empty list `[ ]`.
 (import-tree.addPath ./modules) [ ]
 ```
 
-______________________________________________________________________
+---
 
 ## Why
 
@@ -280,7 +280,7 @@ particular idioms.
 
 @vic is using this on [Dendrix](https://github.com/vic/dendrix) for [community conventions](https://github.com/vic/dendrix/blob/main/dev/modules/community/_pipeline.nix) on tagging files.
 
-This would allow us to have community-driven *sets* of configurations,
+This would allow us to have community-driven _sets_ of configurations,
 much like those popular for editors: spacemacs/lazy-vim distributions.
 
 Imagine an editor distribution exposing the following flake output:
@@ -288,7 +288,7 @@ Imagine an editor distribution exposing the following flake output:
 ```nix
 # editor-distro's flakeModule
 {inputs, lib, ...}:
-let 
+let
   flake.lib.modules-tree = lib.pipe inputs.import-tree [
     (i: i.addPath ./modules)
     (i: i.addAPI { inherit on off exclusive; })
@@ -323,7 +323,7 @@ in {
 }
 ```
 
-______________________________________________________________________
+---
 
 ## Testing
 
@@ -332,7 +332,7 @@ ______________________________________________________________________
 The test suite can be found in [`checkmate.nix`](checkmate.nix). To run it locally:
 
 ```sh
-nix flake check path:checkmate --override-input target path:.
+nix flake check github:vic/checkmate --override-input target path:.
 ```
 
 Run the following to format files:
diff --git a/checkmate/.gitignore b/checkmate/.gitignore
deleted file mode 100644
index 301d47e..0000000
--- a/checkmate/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-flake.lock
diff --git a/checkmate/flake.nix b/checkmate/flake.nix
deleted file mode 100644
index d46b22d..0000000
--- a/checkmate/flake.nix
+++ /dev/null
@@ -1,6 +0,0 @@
-{
-  inputs.target.url = "path:..";
-  inputs.checkmate.url = "github:vic/checkmate";
-  inputs.checkmate.inputs.target.follows = "target";
-  outputs = inputs: inputs.checkmate.lib.newFlake;
-}
diff --git a/checkmate/modules/formatter.nix b/checkmate/modules/formatter.nix
new file mode 100644
index 0000000..7f20dd2
--- /dev/null
+++ b/checkmate/modules/formatter.nix
@@ -0,0 +1,3 @@
+{
+  perSystem.treefmt.settings.global.excludes = [ "checkmate/tree/*" ];
+}
diff --git a/checkmate.nix b/checkmate/modules/tests.nix
similarity index 70%
rename from checkmate.nix
rename to checkmate/modules/tests.nix
index 3b07c99..7b15815 100644
--- a/checkmate.nix
+++ b/checkmate/modules/tests.nix
@@ -13,121 +13,121 @@ in
     {
       nix-unit.tests = {
         leafs."test fails if no lib has been set" = {
-          expr = it.leafs ./trees;
+          expr = it.leafs ../tree;
           expectedError.type = "ThrownError";
         };
 
         leafs."test succeeds when lib has been set" = {
-          expr = (it.withLib lib).leafs ./tree/hello;
+          expr = (it.withLib lib).leafs ../tree/hello;
           expected = [ ];
         };
 
         leafs."test only returns nix non-ignored files" = {
-          expr = lit.leafs ./tree/a;
+          expr = lit.leafs ../tree/a;
           expected = [
-            ./tree/a/a_b.nix
-            ./tree/a/b/b_a.nix
-            ./tree/a/b/m.nix
+            ../tree/a/a_b.nix
+            ../tree/a/b/b_a.nix
+            ../tree/a/b/m.nix
           ];
         };
 
         filter."test returns empty if no nix files with true predicate" = {
-          expr = (lit.filter (_: false)).leafs ./tree;
+          expr = (lit.filter (_: false)).leafs ../tree;
           expected = [ ];
         };
 
         filter."test only returns nix files with true predicate" = {
-          expr = (lit.filter (lib.hasSuffix "m.nix")).leafs ./tree;
-          expected = [ ./tree/a/b/m.nix ];
+          expr = (lit.filter (lib.hasSuffix "m.nix")).leafs ../tree;
+          expected = [ ../tree/a/b/m.nix ];
         };
 
         filter."test multiple `filter`s compose" = {
-          expr = ((lit.filter (lib.hasInfix "b/")).filter (lib.hasInfix "_")).leafs ./tree;
-          expected = [ ./tree/a/b/b_a.nix ];
+          expr = ((lit.filter (lib.hasInfix "b/")).filter (lib.hasInfix "_")).leafs ../tree;
+          expected = [ ../tree/a/b/b_a.nix ];
         };
 
         match."test returns empty if no files match regex" = {
-          expr = (lit.match "badregex").leafs ./tree;
+          expr = (lit.match "badregex").leafs ../tree;
           expected = [ ];
         };
 
         match."test returns files matching regex" = {
-          expr = (lit.match ".*/[^/]+_[^/]+\.nix").leafs ./tree;
+          expr = (lit.match ".*/[^/]+_[^/]+\.nix").leafs ../tree;
           expected = [
-            ./tree/a/a_b.nix
-            ./tree/a/b/b_a.nix
+            ../tree/a/a_b.nix
+            ../tree/a/b/b_a.nix
           ];
         };
 
         matchNot."test returns files not matching regex" = {
-          expr = (lit.matchNot ".*/[^/]+_[^/]+\.nix").leafs ./tree/a/b;
+          expr = (lit.matchNot ".*/[^/]+_[^/]+\.nix").leafs ../tree/a/b;
           expected = [
-            ./tree/a/b/m.nix
+            ../tree/a/b/m.nix
           ];
         };
 
         match."test `match` composes with `filter`" = {
-          expr = ((lit.match ".*a_b.nix").filter (lib.hasInfix "/a/")).leafs ./tree;
-          expected = [ ./tree/a/a_b.nix ];
+          expr = ((lit.match ".*a_b.nix").filter (lib.hasInfix "/a/")).leafs ../tree;
+          expected = [ ../tree/a/a_b.nix ];
         };
 
         match."test multiple `match`s compose" = {
-          expr = ((lit.match ".*/[^/]+_[^/]+\.nix").match ".*b\.nix").leafs ./tree;
-          expected = [ ./tree/a/a_b.nix ];
+          expr = ((lit.match ".*/[^/]+_[^/]+\.nix").match ".*b\.nix").leafs ../tree;
+          expected = [ ../tree/a/a_b.nix ];
         };
 
         map."test transforms each matching file with function" = {
-          expr = (lit.map import).leafs ./tree/x;
+          expr = (lit.map import).leafs ../tree/x;
           expected = [ "z" ];
         };
 
         map."test `map` composes with `filter`" = {
-          expr = ((lit.filter (lib.hasInfix "/x")).map import).leafs ./tree;
+          expr = ((lit.filter (lib.hasInfix "/x")).map import).leafs ../tree;
           expected = [ "z" ];
         };
 
         map."test multiple `map`s compose" = {
-          expr = ((lit.map import).map builtins.stringLength).leafs ./tree/x;
+          expr = ((lit.map import).map builtins.stringLength).leafs ../tree/x;
           expected = [ 1 ];
         };
 
         addPath."test `addPath` prepends a path to filter" = {
-          expr = (lit.addPath ./tree/x).files;
-          expected = [ ./tree/x/y.nix ];
+          expr = (lit.addPath ../tree/x).files;
+          expected = [ ../tree/x/y.nix ];
         };
 
         addPath."test `addPath` can be called multiple times" = {
-          expr = ((lit.addPath ./tree/x).addPath ./tree/a/b).files;
+          expr = ((lit.addPath ../tree/x).addPath ../tree/a/b).files;
           expected = [
-            ./tree/x/y.nix
-            ./tree/a/b/b_a.nix
-            ./tree/a/b/m.nix
+            ../tree/x/y.nix
+            ../tree/a/b/b_a.nix
+            ../tree/a/b/m.nix
           ];
         };
 
         addPath."test `addPath` identity" = {
-          expr = ((lit.addPath ./tree/x).addPath ./tree/a/b).files;
+          expr = ((lit.addPath ../tree/x).addPath ../tree/a/b).files;
           expected = lit.leafs [
-            ./tree/x
-            ./tree/a/b
+            ../tree/x
+            ../tree/a/b
           ];
         };
 
         new."test `new` returns a clear state" = {
           expr = lib.pipe lit [
-            (i: i.addPath ./tree/x)
-            (i: i.addPath ./tree/a/b)
+            (i: i.addPath ../tree/x)
+            (i: i.addPath ../tree/a/b)
             (i: i.new)
-            (i: i.addPath ./tree/modules/hello-world)
+            (i: i.addPath ../tree/modules/hello-world)
             (i: i.withLib lib)
             (i: i.files)
           ];
-          expected = [ ./tree/modules/hello-world/mod.nix ];
+          expected = [ ../tree/modules/hello-world/mod.nix ];
         };
 
         initFilter."test can change the initial filter to look for other file types" = {
-          expr = (lit.initFilter (p: lib.hasSuffix ".txt" p)).leafs [ ./tree/a ];
-          expected = [ ./tree/a/a.txt ];
+          expr = (lit.initFilter (p: lib.hasSuffix ".txt" p)).leafs [ ../tree/a ];
+          expected = [ ../tree/a/a.txt ];
         };
 
         initFilter."test initf does filter non-paths" = {
@@ -153,21 +153,21 @@ in
         addAPI."test extends the API available on an import-tree object" = {
           expr =
             let
-              extended = lit.addAPI { helloOption = self: self.addPath ./tree/modules/hello-option; };
+              extended = lit.addAPI { helloOption = self: self.addPath ../tree/modules/hello-option; };
             in
             extended.helloOption.files;
-          expected = [ ./tree/modules/hello-option/mod.nix ];
+          expected = [ ../tree/modules/hello-option/mod.nix ];
         };
 
         addAPI."test preserves previous API extensions on an import-tree object" = {
           expr =
             let
-              first = lit.addAPI { helloOption = self: self.addPath ./tree/modules/hello-option; };
-              second = first.addAPI { helloWorld = self: self.addPath ./tree/modules/hello-world; };
+              first = lit.addAPI { helloOption = self: self.addPath ../tree/modules/hello-option; };
+              second = first.addAPI { helloWorld = self: self.addPath ../tree/modules/hello-world; };
               extended = second.addAPI { res = self: self.helloOption.files; };
             in
             extended.res;
-          expected = [ ./tree/modules/hello-option/mod.nix ];
+          expected = [ ../tree/modules/hello-option/mod.nix ];
         };
 
         addAPI."test API extensions are late bound" = {
@@ -181,30 +181,30 @@ in
         };
 
         pipeTo."test pipes list into a function" = {
-          expr = (lit.map lib.pathType).pipeTo (lib.length) ./tree/x;
+          expr = (lit.map lib.pathType).pipeTo (lib.length) ../tree/x;
           expected = 1;
         };
 
         import-tree."test does not break if given a path to a file instead of a directory." = {
-          expr = lit.leafs ./tree/x/y.nix;
-          expected = [ ./tree/x/y.nix ];
+          expr = lit.leafs ../tree/x/y.nix;
+          expected = [ ../tree/x/y.nix ];
         };
 
         import-tree."test returns a module with a single imported nested module having leafs" = {
           expr =
             let
               oneElement = arr: if lib.length arr == 1 then lib.elemAt arr 0 else throw "Expected one element";
-              module = it ./tree/x;
+              module = it ../tree/x;
               inner = (oneElement module.imports) { inherit lib; };
             in
             oneElement inner.imports;
-          expected = ./tree/x/y.nix;
+          expected = ../tree/x/y.nix;
         };
 
         import-tree."test evaluates returned module as part of module-eval" = {
           expr =
             let
-              res = lib.modules.evalModules { modules = [ (it ./tree/modules) ]; };
+              res = lib.modules.evalModules { modules = [ (it ../tree/modules) ]; };
             in
             res.config.hello;
           expected = "world";
@@ -213,7 +213,7 @@ in
         import-tree."test can itself be used as a module" = {
           expr =
             let
-              res = lib.modules.evalModules { modules = [ (it.addPath ./tree/modules) ]; };
+              res = lib.modules.evalModules { modules = [ (it.addPath ../tree/modules) ]; };
             in
             res.config.hello;
           expected = "world";
@@ -222,10 +222,10 @@ in
         import-tree."test take as arg anything path convertible" = {
           expr = lit.leafs [
             {
-              outPath = ./tree/modules/hello-world;
+              outPath = ../tree/modules/hello-world;
             }
           ];
-          expected = [ ./tree/modules/hello-world/mod.nix ];
+          expected = [ ../tree/modules/hello-world/mod.nix ];
         };
 
         import-tree."test passes non-paths without string conversion" = {
@@ -247,18 +247,18 @@ in
 
         import-tree."test can take other import-trees as if they were paths" = {
           expr = (lit.filter (lib.hasInfix "mod")).leafs [
-            (it.addPath ./tree/modules/hello-option)
-            ./tree/modules/hello-world
+            (it.addPath ../tree/modules/hello-option)
+            ../tree/modules/hello-world
           ];
           expected = [
-            ./tree/modules/hello-option/mod.nix
-            ./tree/modules/hello-world/mod.nix
+            ../tree/modules/hello-option/mod.nix
+            ../tree/modules/hello-world/mod.nix
           ];
         };
 
         leafs."test loads from hidden directory but excludes sub-hidden" = {
-          expr = lit.leafs ./tree/a/b/_c;
-          expected = [ ./tree/a/b/_c/d/e.nix ];
+          expr = lit.leafs ../tree/a/b/_c;
+          expected = [ ../tree/a/b/_c/d/e.nix ];
         };
       };
 
diff --git a/tree/a/a.txt b/checkmate/tree/a/a.txt
similarity index 100%
rename from tree/a/a.txt
rename to checkmate/tree/a/a.txt
diff --git a/tree/a/a_b.nix b/checkmate/tree/a/a_b.nix
similarity index 100%
rename from tree/a/a_b.nix
rename to checkmate/tree/a/a_b.nix
diff --git a/tree/a/b/_c/d/_f.nix b/checkmate/tree/a/b/_c/d/_f.nix
similarity index 100%
rename from tree/a/b/_c/d/_f.nix
rename to checkmate/tree/a/b/_c/d/_f.nix
diff --git a/tree/a/b/_c/d/e.nix b/checkmate/tree/a/b/_c/d/e.nix
similarity index 100%
rename from tree/a/b/_c/d/e.nix
rename to checkmate/tree/a/b/_c/d/e.nix
diff --git a/tree/a/b/_n.nix b/checkmate/tree/a/b/_n.nix
similarity index 100%
rename from tree/a/b/_n.nix
rename to checkmate/tree/a/b/_n.nix
diff --git a/tree/a/b/b_a.nix b/checkmate/tree/a/b/b_a.nix
similarity index 100%
rename from tree/a/b/b_a.nix
rename to checkmate/tree/a/b/b_a.nix
diff --git a/tree/a/b/m.nix b/checkmate/tree/a/b/m.nix
similarity index 100%
rename from tree/a/b/m.nix
rename to checkmate/tree/a/b/m.nix
diff --git a/tree/hello/world b/checkmate/tree/hello/world
similarity index 100%
rename from tree/hello/world
rename to checkmate/tree/hello/world
diff --git a/tree/modules/hello-option/mod.nix b/checkmate/tree/modules/hello-option/mod.nix
similarity index 100%
rename from tree/modules/hello-option/mod.nix
rename to checkmate/tree/modules/hello-option/mod.nix
diff --git a/tree/modules/hello-world/mod.nix b/checkmate/tree/modules/hello-world/mod.nix
similarity index 100%
rename from tree/modules/hello-world/mod.nix
rename to checkmate/tree/modules/hello-world/mod.nix
diff --git a/tree/x/y.nix b/checkmate/tree/x/y.nix
similarity index 100%
rename from tree/x/y.nix
rename to checkmate/tree/x/y.nix