diff --git a/src/format.rs b/crates/improvise-core/src/format.rs
similarity index 100%
rename from src/format.rs
rename to crates/improvise-core/src/format.rs
diff --git a/crates/improvise-core/src/lib.rs b/crates/improvise-core/src/lib.rs
index 68364e4..e3366de 100644
--- a/crates/improvise-core/src/lib.rs
+++ b/crates/improvise-core/src/lib.rs
@@ -2,5 +2,11 @@
 //! and number formatting. Depends on `improvise-formula` for AST types;
 //! has no awareness of UI, I/O, or commands.
 //!
-//! Scaffolded empty in this commit; the modules land in the next commit.
+//! Re-exports `improvise_formula` under `formula` so internal code can use
+//! `crate::formula::*` paths, mirroring the main crate's convention.
 pub use improvise_formula as formula;
+
+pub mod format;
+pub mod model;
+pub mod view;
+pub mod workbook;
diff --git a/src/model/category.rs b/crates/improvise-core/src/model/category.rs
similarity index 100%
rename from src/model/category.rs
rename to crates/improvise-core/src/model/category.rs
diff --git a/src/model/cell.rs b/crates/improvise-core/src/model/cell.rs
similarity index 100%
rename from src/model/cell.rs
rename to crates/improvise-core/src/model/cell.rs
diff --git a/src/model/mod.rs b/crates/improvise-core/src/model/mod.rs
similarity index 100%
rename from src/model/mod.rs
rename to crates/improvise-core/src/model/mod.rs
diff --git a/src/model/symbol.rs b/crates/improvise-core/src/model/symbol.rs
similarity index 100%
rename from src/model/symbol.rs
rename to crates/improvise-core/src/model/symbol.rs
diff --git a/src/model/types.rs b/crates/improvise-core/src/model/types.rs
similarity index 100%
rename from src/model/types.rs
rename to crates/improvise-core/src/model/types.rs
diff --git a/src/view/axis.rs b/crates/improvise-core/src/view/axis.rs
similarity index 100%
rename from src/view/axis.rs
rename to crates/improvise-core/src/view/axis.rs
diff --git a/src/view/layout.rs b/crates/improvise-core/src/view/layout.rs
similarity index 100%
rename from src/view/layout.rs
rename to crates/improvise-core/src/view/layout.rs
diff --git a/src/view/mod.rs b/crates/improvise-core/src/view/mod.rs
similarity index 100%
rename from src/view/mod.rs
rename to crates/improvise-core/src/view/mod.rs
diff --git a/src/view/types.rs b/crates/improvise-core/src/view/types.rs
similarity index 100%
rename from src/view/types.rs
rename to crates/improvise-core/src/view/types.rs
diff --git a/src/workbook.rs b/crates/improvise-core/src/workbook.rs
similarity index 100%
rename from src/workbook.rs
rename to crates/improvise-core/src/workbook.rs
diff --git a/src/lib.rs b/src/lib.rs
index 19986e6..642b696 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,10 +1,10 @@
 pub mod command;
 pub mod draw;
-pub mod format;
+pub use improvise_core::format;
 pub use improvise_formula as formula;
 pub mod import;
-pub mod model;
+pub use improvise_core::model;
 pub mod persistence;
 pub mod ui;
-pub mod view;
-pub mod workbook;
+pub use improvise_core::view;
+pub use improvise_core::workbook;