diff --git a/src/claml.rs b/src/claml.rs
index 4b0fd9d..a763a5c 100644
--- a/src/claml.rs
+++ b/src/claml.rs
@@ -1 +1,157 @@
-// implemented in a later task
+use crate::model::{AppError, IcdMeta};
+use quick_xml::events::Event;
+use quick_xml::reader::Reader;
+use std::collections::HashMap;
+
+/// Convert a Roman numeral chapter code (I..XXII) to a zero-padded decimal string ("01".."22").
+/// Returns `None` for unrecognised strings.
+fn roman_to_padded(roman: &str) -> Option<String> {
+    let n: u32 = match roman {
+        "I" => 1, "II" => 2, "III" => 3, "IV" => 4, "V" => 5,
+        "VI" => 6, "VII" => 7, "VIII" => 8, "IX" => 9, "X" => 10,
+        "XI" => 11, "XII" => 12, "XIII" => 13, "XIV" => 14, "XV" => 15,
+        "XVI" => 16, "XVII" => 17, "XVIII" => 18, "XIX" => 19, "XX" => 20,
+        "XXI" => 21, "XXII" => 22,
+        _ => return None,
+    };
+    Some(format!("{n:02}"))
+}
+
+/// Stream-parse the ClaML XML into a map keyed by normalised ICD code.
+///
+/// The file is flat: `<Class kind="chapter">` elements close before their
+/// associated `<Class kind="category">` siblings begin.  We therefore track
+/// the most-recently-seen chapter and assign it to every category that
+/// follows, until the next chapter appears.
+pub fn load(path: &str) -> Result<HashMap<String, IcdMeta>, AppError> {
+    let mut reader = Reader::from_file(path)
+        .map_err(|e| AppError::Io(format!("{path}: {e}")))?;
+    reader.config_mut().trim_text(true);
+
+    let mut map: HashMap<String, IcdMeta> = HashMap::new();
+    let mut buf = Vec::new();
+
+    // Active category being built; None when processing non-category Classes.
+    let mut cur: Option<IcdMeta> = None;
+    let mut cur_kind = String::new();
+
+    // The chapter we most recently entered (zero-padded Arabic, e.g. "01").
+    let mut current_chapter = String::new();
+
+    let mut in_preferred = false;
+
+    loop {
+        match reader.read_event_into(&mut buf) {
+            Err(e) => return Err(AppError::Parse(format!("claml: {e}"))),
+            Ok(Event::Eof) => break,
+
+            Ok(Event::Start(ref t)) | Ok(Event::Empty(ref t)) => {
+                let name = t.name();
+                match name.as_ref() {
+                    b"Class" => {
+                        let mut code = String::new();
+                        cur_kind.clear();
+                        for a in t.attributes().flatten() {
+                            match a.key.as_ref() {
+                                b"code" => code = String::from_utf8_lossy(&a.value).into_owned(),
+                                b"kind" => cur_kind = String::from_utf8_lossy(&a.value).into_owned(),
+                                _ => {}
+                            }
+                        }
+                        if cur_kind == "chapter" {
+                            // Update the running chapter for all subsequent categories.
+                            if let Some(padded) = roman_to_padded(&code) {
+                                current_chapter = padded;
+                            }
+                            cur = None;
+                        } else if cur_kind == "category" {
+                            let m = IcdMeta {
+                                code,
+                                chapter: current_chapter.clone(),
+                                ..IcdMeta::default()
+                            };
+                            cur = Some(m);
+                        } else {
+                            cur = None;
+                        }
+                    }
+                    b"SuperClass" => {
+                        if let Some(m) = cur.as_mut() {
+                            for a in t.attributes().flatten() {
+                                if a.key.as_ref() == b"code" {
+                                    let sup = String::from_utf8_lossy(&a.value);
+                                    if m.group.is_empty() {
+                                        m.group = sup.into_owned();
+                                    }
+                                }
+                            }
+                        }
+                    }
+                    b"Meta" => {
+                        if let Some(m) = cur.as_mut() {
+                            let mut k = String::new();
+                            let mut v = String::new();
+                            for a in t.attributes().flatten() {
+                                match a.key.as_ref() {
+                                    b"name" => k = String::from_utf8_lossy(&a.value).into_owned(),
+                                    b"value" => v = String::from_utf8_lossy(&a.value).into_owned(),
+                                    _ => {}
+                                }
+                            }
+                            match k.as_str() {
+                                "Para295" => m.para295 = v,
+                                "Para301" => m.para301 = v,
+                                "Exotic" => m.exotic = v == "J",
+                                "Infectious" => m.ifsg = v == "J",
+                                "Content" => m.content = v == "J",
+                                // A `chapter` Meta overrides the stack-derived value if present.
+                                "chapter" => m.chapter = v,
+                                _ => {}
+                            }
+                        }
+                    }
+                    b"Rubric" => {
+                        let mut rubric_kind = String::new();
+                        for a in t.attributes().flatten() {
+                            if a.key.as_ref() == b"kind" {
+                                rubric_kind = String::from_utf8_lossy(&a.value).into_owned();
+                            }
+                        }
+                        in_preferred = rubric_kind == "preferred";
+                    }
+                    _ => {}
+                }
+            }
+
+            Ok(Event::Text(txt)) => {
+                if in_preferred {
+                    if let Some(m) = cur.as_mut() {
+                        if m.description.is_empty() {
+                            m.description = txt.unescape().unwrap_or_default().into_owned();
+                        }
+                    }
+                }
+            }
+
+            Ok(Event::End(ref t)) => match t.name().as_ref() {
+                b"Rubric" => in_preferred = false,
+                b"Class" => {
+                    if let Some(m) = cur.take() {
+                        if !m.code.is_empty() {
+                            map.insert(m.code.clone(), m);
+                        }
+                    }
+                }
+                _ => {}
+            },
+
+            _ => {}
+        }
+        buf.clear();
+    }
+
+    if map.is_empty() {
+        return Err(AppError::Parse(format!("no ClaML categories in {path}")));
+    }
+    Ok(map)
+}
diff --git a/tests/claml_tests.rs b/tests/claml_tests.rs
new file mode 100644
index 0000000..30b428f
--- /dev/null
+++ b/tests/claml_tests.rs
@@ -0,0 +1,13 @@
+use alpha_id::claml;
+
+#[test]
+fn parses_real_claml_meta_and_titles() {
+    let map = claml::load("icd-claml/Klassifikationsdateien/icd10gm2026syst_claml_20250912.xml").unwrap();
+    let a010 = map.get("A01.0").expect("A01.0 present");
+    assert_eq!(a010.para295, "P");          // billable primary
+    assert_eq!(a010.chapter, "01");
+    assert!(a010.description.contains("Typhus abdominalis"));
+    let a01 = map.get("A01").expect("A01 present");
+    assert_eq!(a01.para295, "V");           // 3-digit non-codable
+    assert!(map.len() > 10_000);
+}