diff --git a/.gitignore b/.gitignore
index 7efb658..bf918a7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,8 +4,6 @@ target
 rust-agentic-task.md
 tasks/artifacts/*
 
-*.stderr
-
 verify/
 reviews/
 
diff --git a/poimen/crates/ids/tests/compile_fail/default_task_id.stderr b/poimen/crates/ids/tests/compile_fail/default_task_id.stderr
new file mode 100644
index 0000000..fb5a93a
--- /dev/null
+++ b/poimen/crates/ids/tests/compile_fail/default_task_id.stderr
@@ -0,0 +1,16 @@
+error[E0599]: no associated function or constant named `default` found for struct `TaskId` in the current scope
+ --> tests/compile_fail/default_task_id.rs:7:28
+  |
+7 |     let _task_id = TaskId::default();
+  |                            ^^^^^^^ associated function or constant not found in `TaskId`
+  |
+note: if you're trying to build a new `TaskId` consider using one of the following associated functions:
+      TaskId::new
+      TaskId::from_bytes
+ --> src/lib.rs
+  |
+  |     pub fn new(hash: blake3::Hash) -> Self {
+  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+  |     pub fn from_bytes(bytes: [u8; 32]) -> Self {
+  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/poimen/crates/ids/tests/compile_fail/unscoped_key.stderr b/poimen/crates/ids/tests/compile_fail/unscoped_key.stderr
new file mode 100644
index 0000000..de5eb45
--- /dev/null
+++ b/poimen/crates/ids/tests/compile_fail/unscoped_key.stderr
@@ -0,0 +1,20 @@
+error[E0277]: the trait bound `RunId: StorageKey` is not satisfied
+  --> tests/compile_fail/unscoped_key.rs:10:16
+   |
+10 |     use_as_key(run_id);
+   |     ---------- ^^^^^^ the trait `StorageKey` is not implemented for `RunId`
+   |     |
+   |     required by a bound introduced by this call
+   |
+help: the following other types implement trait `StorageKey`
+  --> src/lib.rs
+   |
+   | impl<T> StorageKey for Scoped<T> where T: Serialize + for<'de> Deserialize<'de> {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Scoped<T>`
+   | impl StorageKey for BranchKey {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `BranchKey`
+note: required by a bound in `use_as_key`
+  --> tests/compile_fail/unscoped_key.rs:6:18
+   |
+ 6 | fn use_as_key<K: StorageKey>(_key: K) {}
+   |                  ^^^^^^^^^^ required by this bound in `use_as_key`