diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index 2a9084e..e596e1d 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -1,3 +1,33 @@
 # C2
 C2 is a compiler for a new language.
 See the README.md for information about this project.
+
+## Code Changes
+After every code change, ensure the binary builds correctly,
+and run the unit tests (`make test`).
+
+Ensure that every new function and code path has useful unit tests.
+
+### Creating Source Files
+Whenever a new source file is created, it must be added to the `include.mk` file.
+A test file should also be created.
+
+Test source files do not have to be added to the include.mk file.
+These are added to the `test.c` file by means of directly `#include`ing the C file.
+
+### Testing
+Any test source code must be prefixed with test_xyz, where xyz matches
+the source file it is trying to test.
+For instance, a test for `buffer.c` must be called `test_buffer.c`.
+
+There will be no `test_buffer.h`. Instead, `test.c` will directly
+`#include` the C–source-file directly.
+
+## Language Syntax
+Since this is a compiler for a new language, do not assume anything
+of its syntax.
+Always check the `specs` directory.
+
+If there is anything unclear, ask the user for clarification.
+It is certainly possible that there are contradictions in the
+spec that have to be solved first.
diff --git a/.github/skills/implement/SKILL.md b/.github/skills/implement/SKILL.md
index 4ec1c4d..6a54071 100644
--- a/.github/skills/implement/SKILL.md
+++ b/.github/skills/implement/SKILL.md
@@ -2,5 +2,13 @@
 name: implement
 description: 'Implement all @copilot annotations'
 ---
+# General
+Find and implement all `@copilot` comments in the codebase. Modify only code related to those annotations, and always make sure that tests are added.
 
-Find and implement all `@copilot` comments in the codebase. Only modify code related to those annotations. Skip e2e tests unless asked.
\ No newline at end of file
+## Plan Mode
+If you are currently in plan mode, look at all the annotations and always create a plan first.
+Only start modifying code once the plan has been approved by the user.
+
+## Implementation
+Implement the changes requested at the location of the annotation.
+After the implementation is finished, remove the comment containing the annotation.
diff --git a/.gitignore b/.gitignore
index e660fd9..3e029b1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1 @@
-bin/
+/c2
diff --git a/Makefile b/Makefile
index ece90db..fb0c20f 100644
--- a/Makefile
+++ b/Makefile
@@ -7,4 +7,7 @@ c2: v0/bin/c2
 
 test::
 
+clean::
+	rm -f c2
+
 include v0/include.mk
\ No newline at end of file
diff --git a/README.md b/README.md
index af4d241..7f442ee 100644
--- a/README.md
+++ b/README.md
@@ -14,4 +14,4 @@ In order to run the tests, run `make test`.
 The current version is v0. Its source code lives in the `v0` directory.
 
 ## Languages Specifications
-See the specs directory for information on the actual language syntax.
\ No newline at end of file
+See the specs directory for information on the actual language syntax.
diff --git a/copilot-instructions.md b/copilot-instructions.md
new file mode 100644
index 0000000..4b6b545
--- /dev/null
+++ b/copilot-instructions.md
@@ -0,0 +1,9 @@
+Copilot / contributor instructions for v0
+
+- When adding new source or test files for v0, do NOT rely on wildcards. Add the file path explicitly to v0/include.mk in either V0_SRC (for library/source files) or V0_TEST (for test files beginning with `test_`).
+- v0/include.mk is included by the top-level Makefile and is a dependency for object builds. Modifying v0/include.mk will force appropriate recompilation.
+
+Example:
+V0_SRC := v0/buffer.c v0/main.c
+V0_TEST := v0/test.c v0/test_buffer.c
+
diff --git a/specs/GENERAL.md b/specs/GENERAL.md
new file mode 100644
index 0000000..9da3181
--- /dev/null
+++ b/specs/GENERAL.md
@@ -0,0 +1,14 @@
+# General
+A C2–file starts with a module declaration followed by other declarations.
+
+For instance:
+
+```c2
+module mymodule;
+
+import libc.stdio;
+
+void main() {
+	puts("Hello, world!");
+}
+```
diff --git a/v0/.gitignore b/v0/.gitignore
new file mode 100644
index 0000000..65776c3
--- /dev/null
+++ b/v0/.gitignore
@@ -0,0 +1 @@
+/bin/
\ No newline at end of file
diff --git a/v0/test.c b/v0/test.c
index 78c7c1e..00af902 100644
--- a/v0/test.c
+++ b/v0/test.c
@@ -1,5 +1,5 @@
 #include "test.h"
-#include "../src/buffer.h"
+#include "buffer.h"
 #include <setjmp.h>
 #include <stdio.h>