diff --git a/.ocamlformat b/.ocamlformat
new file mode 100644
index 0000000..78e716a
--- /dev/null
+++ b/.ocamlformat
@@ -0,0 +1,10 @@
+profile = janestreet
+
+margin = 100
+doc-comments-padding = 100
+exp-grouping = preserve
+break-string-literals = never
+
+module-item-spacing = preserve
+exp-grouping = preserve
+sequence-blank-line = preserve
diff --git a/dune-project b/dune-project
index eb73cd8..682ca2b 100644
--- a/dune-project
+++ b/dune-project
@@ -10,10 +10,14 @@
 (documentation https://url/to/documentation)
 (package
  (name lithos)
- (synopsis "A short synopsis")
- (description "A longer description")
- (depends ocaml)
- (tags
-  ("add topics" "to describe" your project)))
+ (synopsis "Embedded key-value database inspired by BoltDB")
+ (description "Lithos is an embedded, transactional key-value database written in OCaml. It provides MVCC with single-writer/multi-reader semantics and a functional API.")
+ (depends
+  (ocaml (>= 4.14))
+  dune
+  (cmdliner (>= 1.2.0))
+  (alcotest :with-test)
+  (odoc :with-doc))
+ (tags (database "key-value" embedded transactional MVCC)))
 
 ; See https://dune.readthedocs.io/en/stable/reference/dune-project/index.html
diff --git a/lib/dune b/lib/dune
index f4f6842..ed5cadd 100644
--- a/lib/dune
+++ b/lib/dune
@@ -1,2 +1,3 @@
 (library
- (name lithos))
+ (name lithos)
+ (libraries unix))
diff --git a/lib/error.ml b/lib/error.ml
new file mode 100644
index 0000000..765e949
--- /dev/null
+++ b/lib/error.ml
@@ -0,0 +1,16 @@
+(** Error types for Lithos database operations *)
+
+type t =
+  | IO_error of string
+  | Invalid_database of string
+  | Database_locked
+  | Not_found
+
+let to_string = function
+  | IO_error msg -> Printf.sprintf "I/O error: %s" msg
+  | Invalid_database msg -> Printf.sprintf "Invalid database: %s" msg
+  | Database_locked -> "Database is locked"
+  | Not_found -> "Not found"
+;;
+
+let of_unix_error err path = IO_error (Printf.sprintf "%s: %s" (Unix.error_message err) path)
diff --git a/lib/error.mli b/lib/error.mli
new file mode 100644
index 0000000..8f530c6
--- /dev/null
+++ b/lib/error.mli
@@ -0,0 +1,13 @@
+(** Error types for Lithos database operations *)
+
+type t =
+  | IO_error of string
+  | Invalid_database of string
+  | Database_locked
+  | Not_found
+
+(** Convert error to human-readable string *)
+val to_string : t -> string
+
+(** Create an I/O error from a Unix error *)
+val of_unix_error : Unix.error -> string -> t
diff --git a/lithos.opam b/lithos.opam
index e69de29..bb18b42 100644
--- a/lithos.opam
+++ b/lithos.opam
@@ -0,0 +1,35 @@
+# This file is generated by dune, edit dune-project instead
+opam-version: "2.0"
+synopsis: "Embedded key-value database inspired by BoltDB"
+description:
+  "Lithos is an embedded, transactional key-value database written in OCaml. It provides MVCC with single-writer/multi-reader semantics and a functional API."
+maintainer: ["Owais J <desertthunder.dev@gmail.com>"]
+authors: ["Owais J <desertthunder.dev@gmail.com>"]
+license: "MIT"
+tags: ["database" "key-value" "embedded" "transactional" "MVCC"]
+homepage: "https://github.com/desertthunder/lithos"
+doc: "https://url/to/documentation"
+bug-reports: "https://github.com/desertthunder/lithos/issues"
+depends: [
+  "ocaml" {>= "4.14"}
+  "dune" {>= "3.18"}
+  "cmdliner" {>= "1.2.0"}
+  "alcotest" {with-test}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/desertthunder/lithos.git"
+x-maintenance-intent: ["(latest)"]
diff --git a/test/dune b/test/dune
index 0c0f20e..208a81a 100644
--- a/test/dune
+++ b/test/dune
@@ -1,2 +1,3 @@
 (test
- (name test_lithos))
+ (name test_lithos)
+ (libraries lithos alcotest))
diff --git a/test/test_error.ml b/test/test_error.ml
new file mode 100644
index 0000000..3089214
--- /dev/null
+++ b/test/test_error.ml
@@ -0,0 +1,27 @@
+(** Tests for Error module *)
+
+let test_to_string () =
+  let open Lithos.Error in
+  Alcotest.(check string)
+    "IO_error message"
+    "I/O error: file not found"
+    (to_string (IO_error "file not found"));
+  Alcotest.(check string)
+    "Invalid_database message"
+    "Invalid database: bad header"
+    (to_string (Invalid_database "bad header"));
+  Alcotest.(check string) "Database_locked message" "Database is locked" (to_string Database_locked);
+  Alcotest.(check string) "Not_found message" "Not found" (to_string Not_found)
+;;
+
+let test_of_unix_error () =
+  let open Lithos.Error in
+  let err = of_unix_error Unix.ENOENT "/tmp/test.db" in
+  let msg = to_string err in
+  Alcotest.(check bool)
+    "Unix error contains path"
+    true
+    (String.length msg > 0 && String.contains msg '/')
+;;
+
+let suite = [ "to_string", `Quick, test_to_string; "of_unix_error", `Quick, test_of_unix_error ]
diff --git a/test/test_lithos.ml b/test/test_lithos.ml
index e69de29..edbbdb6 100644
--- a/test/test_lithos.ml
+++ b/test/test_lithos.ml
@@ -0,0 +1,3 @@
+(** Main test suite for Lithos *)
+
+let () = Alcotest.run "Lithos" [ "Error", Test_error.suite ]