fix: recognize NPA shorthand and ordinal PA names (3rd pa → D0230)

- Add parseMultiPaCode: "4PA #3 #14 #19 #30" expands to D0220 + 3× D0230 with tooth numbers
- Add "3rd pa"–"6th pa" direct aliases → D0230 as fallback
- Tighten LLM prompt to always use "2nd pa" for all additional PAs, never "3rd pa" etc.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/Backend/src/ai/cdt-lookup.ts

@@ -156,6 +156,10 @@ const DIRECT_CODE_MAP: Record<string, string> = {
   "1 pa":                   "D0220",
   "first pa":               "D0220",
   "2nd pa":                 "D0230",
+  "3rd pa":                 "D0230",
+  "4th pa":                 "D0230",
+  "5th pa":                 "D0230",
+  "6th pa":                 "D0230",
   "additional pa":          "D0230",
   "cbct":                   "D0367",
   "cone beam":              "D0367",
@@ -287,6 +291,37 @@ function parseCompositeCode(input: string): CdtMatch | null {
   return { code, description: row?.Description ?? code, input, toothNumber: String(toothNum), toothSurface: surfaces.toUpperCase() };
 }
 
+/**
+ * Parse multi-PA shorthand: "4PA", "4 PA", "4PA #3 #14 #19 #30", etc.
+ * NPA → 1× D0220 (first image) + (N-1)× D0230 (each additional).
+ * Tooth numbers, if provided in order, are assigned to each code.
+ */
+function parseMultiPaCode(input: string): CdtMatch[] | null {
+  const m = input.trim().match(/^(\d+)\s*pa\b/i);
+  if (!m) return null;
+
+  const count = parseInt(m[1]!, 10);
+  if (count < 1 || count > 20) return null;
+
+  // Extract all tooth numbers from the full input string
+  const toothMatches = [...input.matchAll(/#\s*(\d{1,2})\b/g)];
+  const teeth: string[] = toothMatches
+    .map((tm) => tm[1]!)
+    .filter((t) => { const n = parseInt(t, 10); return n >= 1 && n <= 32; });
+
+  const d0220 = ALL_CODES.find((r) => r["Procedure Code"] === "D0220");
+  const d0230 = ALL_CODES.find((r) => r["Procedure Code"] === "D0230");
+
+  const results: CdtMatch[] = [];
+  for (let i = 0; i < count; i++) {
+    const code = i === 0 ? "D0220" : "D0230";
+    const desc = i === 0 ? (d0220?.Description ?? "D0220") : (d0230?.Description ?? "D0230");
+    const tooth = teeth[i];
+    results.push({ code, description: desc, input, ...(tooth ? { toothNumber: tooth } : {}) });
+  }
+  return results;
+}
+
 /**
  * Parse SRP code with quadrant: "D4341 UL", "4341 LR", "D4342 UR", etc.
  * UL/UR/LL/LR only appear with D4341 or D4342.
@@ -443,19 +478,23 @@ export function lookupCdtCodes(
       return { code, description: row?.Description ?? code, input: name, ...toothInfo };
     }
 
-    // 2. Composite filling by tooth# and surfaces — also determines CDT code from tooth position
+    // 2. Multi-PA shorthand: "4PA", "4PA #3 #14 #19 #30", etc.
+    const multiPaMatches = parseMultiPaCode(name);
+    if (multiPaMatches) return multiPaMatches;
+
+    // 3. Composite filling by tooth# and surfaces — also determines CDT code from tooth position
     const compositeMatch = parseCompositeCode(name);
     if (compositeMatch) return compositeMatch; // already carries toothNumber/toothSurface
 
-    // 2b. RCT by tooth# — D3310/D3320/D3330 based on tooth position
+    // 4. RCT by tooth# — D3310/D3320/D3330 based on tooth position
     const rctMatch = parseRctCode(name);
     if (rctMatch) return rctMatch;
 
-    // 2c. SRP + quadrant — D4341/D4342 with UL/UR/LL/LR
+    // 5. SRP + quadrant — D4341/D4342 with UL/UR/LL/LR
     const srpMatch = parseSrpCode(name);
     if (srpMatch) return srpMatch;
 
-    // 3. Hardcoded direct code map (short abbreviations / codes not in MH schedule)
+    // 6. Hardcoded direct code map (short abbreviations / codes not in MH schedule)
     const directKey = DIRECT_CODE_MAP[cleaned] ? cleaned : DIRECT_CODE_MAP[strippedCleaned] ? strippedCleaned : null;
     if (directKey) {
       const code = DIRECT_CODE_MAP[directKey]!;
@@ -463,7 +502,7 @@ export function lookupCdtCodes(
       return { code, description: row?.Description ?? code, input: name, ...toothInfo };
     }
 
-    // 4. Hardcoded alias + keyword search (try stripped name so tooth# doesn't break matching)
+    // 7. Hardcoded alias + keyword search (try stripped name so tooth# doesn't break matching)
     const match = matchOne(strippedCleaned !== cleaned ? strippedCleaned : name);
     if (match) return { ...match, input: name, ...toothInfo };
 

apps/Backend/src/ai/internal-chat-graph.ts

@@ -148,9 +148,10 @@ Rules:
 - For SRP with a quadrant abbreviation (UL, UR, LL, LR), keep the code and quadrant together as one entry:
   e.g. "D4341 UL", "4341 LR", "D4342 UR" — the quadrant always travels with the SRP code
 - For multiple PA X-rays with tooth numbers, expand each PA into its own entry:
-  "1 pa, #T" for the first tooth, "2nd pa, #T" for each additional tooth
+  ALWAYS use "1 pa, #T" for the first tooth and "2nd pa, #T" for EVERY additional tooth (never "3rd pa", "4th pa", etc.)
   e.g. "2 PA (#30, 15)" → ["1 pa, #30", "2nd pa, #15"]
   e.g. "3 PA (#3, 14, 30)" → ["1 pa, #3", "2nd pa, #14", "2nd pa, #30"]
+  e.g. "4 PA (#3, 14, 19, 30)" → ["1 pa, #3", "2nd pa, #14", "2nd pa, #19", "2nd pa, #30"]
   e.g. "2 pa #3 #14" → ["1 pa, #3", "2nd pa, #14"]
 - insuranceHint is only set when the user explicitly names an insurance in the message
 - renderingProvider is only set when the user explicitly names a treating/rendering provider or doctor