refactor: input contract — one extracted phrase per line (spec §1a)

split_segments now treats each non-empty trimmed line as one retrieval
unit; blank lines are skipped, not paragraph delimiters. Name/signature
retained (minimal-churn decision). Full suite 45/0. End-to-end: feeding
the GP dictation as extracted phrases recovers I10.90 (rank 4) which was
entirely missing in both modes under the paragraph contract, and largely
dissolves the cross-segment diabetes crowding.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/segment.rs

@@ -1,20 +1,13 @@
-/// Split a dictation into Befund segments on Markdown paragraph
-/// breaks (one or more blank lines). Trims each segment; drops empties.
-pub fn split_segments(dictation: &str) -> Vec<String> {
-    let mut segments = Vec::new();
-    let mut current: Vec<&str> = Vec::new();
-    for line in dictation.lines() {
-        if line.trim().is_empty() {
-            if !current.is_empty() {
-                segments.push(current.join("\n").trim().to_string());
-                current.clear();
-            }
-        } else {
-            current.push(line);
-        }
-    }
-    if !current.is_empty() {
-        segments.push(current.join("\n").trim().to_string());
-    }
-    segments.into_iter().filter(|s| !s.is_empty()).collect()
+/// Split the caller-extracted phrase list into retrieval units: one
+/// non-empty (trimmed) input line = one unit. Blank/whitespace-only
+/// lines are skipped. Rev 2026-05-18 (spec §1a): input is extracted
+/// diagnostic phrases, not a blank-line-segmented dictation. Name and
+/// signature kept; a "segment" now denotes one extracted phrase.
+pub fn split_segments(phrases: &str) -> Vec<String> {
+    phrases
+        .lines()
+        .map(|l| l.trim())
+        .filter(|l| !l.is_empty())
+        .map(|l| l.to_string())
+        .collect()
 }

tests/segment_tests.rs

@@ -1,22 +1,30 @@
 use alpha_id::segment::split_segments;
 
 #[test]
-fn splits_on_blank_lines() {
-    let d = "Befund eins\nmit Zeile zwei\n\nBefund zwei\n\n\nBefund drei\n";
-    let segs = split_segments(d);
-    assert_eq!(segs, vec![
-        "Befund eins\nmit Zeile zwei".to_string(),
-        "Befund zwei".to_string(),
-        "Befund drei".to_string(),
+fn one_unit_per_nonempty_line() {
+    let input = "arterielle Hypertonie\nTyp-2-Diabetes mit Polyneuropathie\ngemischte Hyperlipidämie";
+    assert_eq!(split_segments(input), vec![
+        "arterielle Hypertonie".to_string(),
+        "Typ-2-Diabetes mit Polyneuropathie".to_string(),
+        "gemischte Hyperlipidämie".to_string(),
     ]);
 }
 
 #[test]
-fn single_segment_when_no_blank_line() {
-    assert_eq!(split_segments("nur ein Befund"), vec!["nur ein Befund".to_string()]);
+fn blank_and_whitespace_lines_are_skipped_and_each_line_trimmed() {
+    let input = "  \n\n  Kreuzschmerz \n   \nGonarthrose rechts\n\n";
+    assert_eq!(split_segments(input), vec![
+        "Kreuzschmerz".to_string(),
+        "Gonarthrose rechts".to_string(),
+    ]);
 }
 
 #[test]
-fn empty_input_yields_no_segments() {
+fn single_phrase_is_one_unit() {
+    assert_eq!(split_segments("nur eine Diagnose"), vec!["nur eine Diagnose".to_string()]);
+}
+
+#[test]
+fn empty_or_whitespace_only_input_yields_no_units() {
     assert!(split_segments("   \n\n").is_empty());
 }