Near-miss radar (#3): dead endings one phoneme from a rhyme

A line ending that rhymes with nothing but sits one phoneme from
another ending in the stanza (hand/bond — one vowel apart) gets a
dotted gold underline: a tiny edit would lock it. Restricted to
genuinely-open endings, so it never duplicates the slant/consonance
detection (which already catches same-vowel near-rhymes).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app.py

@@ -1350,7 +1350,7 @@ def analyze(draft: Draft):
             for e in entries:
                 e["target"] = mode
 
-    # per-word stress for the optional dots layer (2+ syllables only —
+    # per-word stress for the optional dots layer    # per-word stress for the optional dots layer (2+ syllables only —
     # a dot under every monosyllable is noise, not information)
     stress_out = []
     for t in tokens:
@@ -1407,9 +1407,54 @@ def analyze(draft: Draft):
         if i not in end_gid and end_word_counts[t["word"].lower()] < 2:
             open_out.append({"l": i, "s": t["start"], "e": t["end"]})
 
+    # near-miss radar: a DEAD line ending (rhymes with nothing) that is
+    # one phoneme from another ending in the stanza — a salvageable line
+    near_out = []
+    open_ids = {(o["l"], o["s"]) for o in open_out}
+    ends_by_st = defaultdict(list)
+    for t in tokens:
+        if t["is_end"] and t["word"].lower() not in STOPWORDS:
+            ph = phones_for(t["word"])
+            if ph:
+                ends_by_st[t["sid"]].append((t, _rime_from_phones(ph)))
+
+    def _one_off(a1, b1):
+        pa, pb = a1.split(), b1.split()
+        if pa == pb:
+            return False
+        if abs(len(pa) - len(pb)) > 1:
+            return False
+        i = j = edits = 0
+        while i < len(pa) and j < len(pb):
+            if pa[i] == pb[j]:
+                i += 1; j += 1
+            else:
+                edits += 1
+                if edits > 1:
+                    return False
+                if len(pa) > len(pb): i += 1
+                elif len(pb) > len(pa): j += 1
+                else: i += 1; j += 1
+        if (len(pa) - i) + (len(pb) - j) + edits != 1:
+            return False
+        return pa[0] == pb[0] or pa[-1] == pb[-1]  # share nucleus or coda
+
+    for ends in ends_by_st.values():
+        for ta, ra in ends:
+            if (ta["line"], ta["start"]) not in open_ids:
+                continue  # only flag endings that currently rhyme nothing
+            for tb, rb in ends:
+                if tb is ta or ta["word"].lower() == tb["word"].lower():
+                    continue
+                if _one_off(ra, rb):
+                    near_out.append({"l": ta["line"], "s": ta["start"],
+                                     "e": ta["end"]})
+                    break
+
+
     return {"lines": lines, "tokens": toks_out, "groups": groups_out,
             "stanzas": stanzas, "meter": meter, "stress": stress_out,
-            "allit": allit_out, "open": open_out}
+            "allit": allit_out, "open": open_out, "near": near_out}
 
 
 # --------------------------------------------------------------------------

static/index.html

@@ -575,12 +575,14 @@ function render(){
   const tokByLine = {};
   const allitByLine = {};
   const openByLine = {};
+  const nearByLine = {};
   const groupInfo = {};
   if(analysis){
     analysis.groups.forEach(g=>{ groupInfo[g.id] = g; });
     analysis.tokens.forEach(t=>{ (tokByLine[t.l] ||= []).push(t); });
     if(analysis.allit) analysis.allit.forEach(t=>{ (allitByLine[t.l] ||= []).push(t); });
     if(analysis.open) analysis.open.forEach(t=>{ (openByLine[t.l] ||= []).push(t); });
+    if(analysis.near) analysis.near.forEach(t=>{ (nearByLine[t.l] ||= []).push(t); });
   }
   const colorOf = t => `var(--r${groupInfo[t.g].color % COLORS})`;
   let html = '';
@@ -604,6 +606,7 @@ function render(){
     const phrases = toks.filter(t=>t.ph);
     const als = (allitToggle.checked && fresh) ? (allitByLine[i] || []) : [];
     const opens = (rhymeToggle.checked && fresh) ? (openByLine[i] || []) : [];
+    const nears = (rhymeToggle.checked && fresh) ? (nearByLine[i] || []) : [];
     let h = '';
     if(!toks.length && !als.length && !opens.length){
       h = esc(line);
@@ -612,6 +615,7 @@ function render(){
       toks.forEach(t=>{ cuts.add(t.s); cuts.add(t.e); if(t.rs != null) cuts.add(t.rs); });
       als.forEach(t=>{ cuts.add(t.s); cuts.add(t.e); });
       opens.forEach(t=>{ cuts.add(t.s); cuts.add(t.e); });
+      nears.forEach(t=>{ cuts.add(t.s); cuts.add(t.e); });
       const pts = [...cuts].sort((a,b)=>a-b);
       for(let k = 0; k < pts.length - 1; k++){
         const a = pts[k], b = pts[k+1];
@@ -621,7 +625,8 @@ function render(){
         const p = phrases.find(t=>t.s <= a && b <= t.e);
         const al = als.find(t=>t.s <= a && b <= t.e);
         const op = opens.find(t=>t.s <= a && b <= t.e);
-        if(!w && !p && !al && !op){ h += text; continue; }
+        const nr = nears.find(t=>t.s <= a && b <= t.e);
+        if(!w && !p && !al && !op && !nr){ h += text; continue; }
         // whole word fills dimly; the rhyming part gets a bright underline.
         // gray = an ending still waiting for its answer
         let style = '';
@@ -646,6 +651,7 @@ function render(){
           style += `background:color-mix(in srgb, var(--ink-dim) 13%, transparent);`;
         }
         if(al) shadows.push(`inset 0 -2px 0 0 color-mix(in srgb, var(--r${al.g % COLORS}) 75%, transparent)`);
+        if(nr) style += 'text-decoration:underline dotted color-mix(in srgb, var(--accent-2) 60%, transparent);text-underline-offset:3px;';
         if(shadows.length) style += `box-shadow:${shadows.join(',')};`;
         h += `<span class="hseg" style="${style}">${text}</span>`;
       }

tests/test_rhymes.py

@@ -746,3 +746,11 @@ def test_rhyme_char_start():
     from app import rhyme_char_start
     assert rhyme_char_start("tonight") == 3   # "ight"
     assert rhyme_char_start("write") == 2     # 'ite' (silent-e skipped)
+
+
+def test_near_miss_radar():
+    # two dead endings one vowel apart get flagged; true rhymes don't
+    text = ("I raise my hand\nlook at the bond\nthe city sleeps\nthe ocean wakes")
+    res = analyze(Draft(text=text))
+    near = {res["lines"][t["l"]][t["s"]:t["e"]].lower() for t in res["near"]}
+    assert near == {"hand", "bond"}