commit c9c479b8738b19de8fa2f6022097931689c123a5
Author: Alex Selimov <alex@alexselimov.com>
Date:   Mon Jun 29 21:19:32 2026 -0400

    Initial commit with basic Date type done

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..2f7896d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+target/
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..aed3e29
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,82 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "anyhow"
+version = "1.0.103"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a4385e2e34eb35d6b3efe798b9eb88096925d87726c0798709bf56d9ed84af3"
+
+[[package]]
+name = "habitrs"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "serde",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.106"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8fd00f0bb2e90d81d1044c2b32617f68fcb9fa3bb7640c23e9c748e53fb30934"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.46"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dfbc457d0c7a0759a614551b11a6409e5951f6c7537be1f1b7682b9ae9230368"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "serde"
+version = "1.0.228"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a8e94ea7f378bd32cbbd37198a4a91436180c5bb472411e48b5ec2e2124ae9e"
+dependencies = [
+ "serde_core",
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_core"
+version = "1.0.228"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41d385c7d4ca58e59fc732af25c3983b67ac852c1a25000afe1175de458b67ad"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.228"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d540f220d3187173da220f885ab66608367b6574e925011a9353e4badda91d79"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.118"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b9ae57f904213ebb649ce6895b8a66c66f0203b9319718f69a5612a065b1422"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6e4313cd5fcd3dad5cafa179702e2b244f760991f45397d14d4ebf38247da75"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..3eb5e9f
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "habitrs"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+anyhow = { version = "1.0.103", features = ["std"] }
+serde = { version = "1.0.228", features = ["derive"] }
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..2e22a07
--- /dev/null
+++ b/README.md
@@ -0,0 +1,3 @@
+# Simple Rust habit tracker
+
+Simple Rust habit tracker intended to integrate with the greater RLOS ecosystem.
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..65880be
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1 @@
+pub mod model;
diff --git a/src/model.rs b/src/model.rs
new file mode 100644
index 0000000..0e9ee45
--- /dev/null
+++ b/src/model.rs
@@ -0,0 +1,102 @@
+use std::collections::HashSet;
+
+use anyhow::{anyhow, bail};
+
+pub struct Date {
+    pub day: u8,
+    pub month: u8,
+    pub year: u16,
+}
+
+impl Date {
+    /// Create a day from String. Expects strings in format '06-26-2026'
+    pub fn from_string(val: &str) -> anyhow::Result<Self> {
+        let mut parts = val.split("-");
+        let month = parts
+            .next()
+            .ok_or(anyhow!("Month missing from date string"))?
+            .parse()?;
+
+        if month > 12 || month == 0 {
+            bail!("Month should be > 0 and <= 12")
+        }
+
+        let day = parts
+            .next()
+            .ok_or(anyhow!("Day missing from date string"))?
+            .parse()?;
+
+        if day == 0 {
+            bail!("Day must be > 0")
+        }
+
+        match month {
+            2 => {
+                if day > 29 {
+                    bail!("February can have a max of 29 days (on leap years)")
+                }
+            }
+            4 | 6 | 9 | 11 => {
+                if day > 30 {
+                    bail!("The provided month only has 30 days")
+                }
+            }
+            1 | 3 | 5 | 7 | 8 | 10 | 12 => {
+                if day > 31 {
+                    bail!("The provided month only has 31 days")
+                }
+            }
+            _ => unreachable!(),
+        }
+
+        let year = parts
+            .next()
+            .ok_or(anyhow!("Year missing from date string"))?
+            .parse()?;
+
+        Ok(Date { day, month, year })
+    }
+}
+
+pub struct Habit {
+    pub name: String,
+    pub days_completed: HashSet<Date>,
+}
+
+#[cfg(test)]
+mod test {
+    use crate::model::Date;
+
+    #[test]
+    fn correct_date_gets_parsed() {
+        let date = Date::from_string("06-16-2026").unwrap();
+
+        assert_eq!(date.day, 16);
+        assert_eq!(date.month, 6);
+        assert_eq!(date.year, 2026);
+
+        let date = Date::from_string("6-16-2026").unwrap();
+
+        assert_eq!(date.day, 16);
+        assert_eq!(date.month, 6);
+        assert_eq!(date.year, 2026);
+
+        let date = Date::from_string("6-6-2026").unwrap();
+
+        assert_eq!(date.day, 6);
+        assert_eq!(date.month, 6);
+        assert_eq!(date.year, 2026);
+    }
+
+    #[test]
+    fn bad_date_doesnt_get_parsed() {
+        let date = Date::from_string("-12-2026");
+        assert!(date.is_err());
+
+        let date = Date::from_string("13-01-2026");
+        assert!(date.is_err());
+
+        let date = Date::from_string("01-32-2026");
+        assert!(date.is_err());
+    }
+}