feat(backend): read a spoken tooth number as its FDI code

The prompt had this backwards. "Never output an FDI tooth code unless the
speaker used FDI notation. Prefer arch + side + position" pushed the model
to decompose speech into "upper / patient_right / six", so the clinician
effectively had to *describe* every tooth. Saying "دندون بیست و شش" — the
way a dentist actually dictates — was the unsupported path.

FDI is what clinicians speak, so the prompt now teaches the notation
instead of forbidding it: first digit = quadrant from the patient's own
point of view, second digit = position from the midline. arch/side/position
stays as the reading of a *described* tooth, where a single digit is a
position and the quadrant comes from words.

Two guards come with it, because bare numbers are now teeth: a single digit
alone still refuses to guess a quadrant, and dates, counts and quantities
are explicitly not teeth.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

backend/src/modules/voice/extraction.prompt.ts

@@ -3,21 +3,19 @@ import type { ExtractionCatalog } from './voice.providers';
 /** Locale-specific guidance. Only the tooth vocabulary and numbering habits differ. */
 const LOCALE_NOTES: Record<string, string> = {
   fa: [
-    'The clinician is speaking Persian. Tooth references are usually quadrant-relative:',
+    'The clinician is speaking Persian. A tooth number can be said as a whole number',
+    '("بیست و شش" = 26), digit by digit ("دو شش" = 26), or with a lead-in',
+    '("دندون شماره ۲۶"). Digits may arrive in Persian or Latin script — either way, copy',
+    'the number into "fdi" as two Latin digits. The descriptive form is quadrant-relative:',
     '"شش بالا راست" = upper right six -> arch "upper", side "patient_right", position 6.',
-    'Digits may appear in Persian or Latin script. Two-digit FDI notation ("یک چهار") does',
-    'occur — use the "fdi" field only for that.',
-    'A bare "دندون دو" carries no quadrant: report position 2 with arch and side null.',
   ].join(' '),
   nl: [
-    'The clinician is speaking Dutch and uses FDI notation, which is standard in the',
-    'Netherlands. "rechtsboven zes" = upper right six. A bare two-digit number is FDI.',
+    'The clinician is speaking Dutch, where FDI is standard. "zesentwintig" and "26" are',
+    'tooth 26. The descriptive form is "rechtsboven zes" = upper right six.',
   ].join(' '),
   en: [
-    'The clinician is speaking English. IMPORTANT: a bare two-digit number is ambiguous,',
-    'because Universal numbering and FDI disagree ("tooth 14" is a different tooth in each).',
-    'Set "fdi" ONLY when the speaker made the notation explicit (e.g. "FDI one four").',
-    'Otherwise describe the tooth with arch/side/position, or leave it unresolved.',
+    'The clinician is speaking English and uses FDI. "twenty-six", "two six" and "26" are',
+    'all tooth 26. The descriptive form is "upper right six".',
   ].join(' '),
 };
 
@@ -41,19 +39,32 @@ export function buildExtractionPrompt(
     '1. Never invent a code. treatmentType, prosthesisDefaultType and prosthesisOverrides[].type',
     '   must be codes from the lists below. labId must be an id from the lab list. If what you',
     '   heard is not in a list, use null.',
-    '2. Never output an FDI tooth code unless the speaker used FDI notation. Prefer',
-    '   arch + side + position.',
-    '3. "side" is always the PATIENT\'s side. The patient\'s upper right is quadrant 1. Never',
+    '2. "side" is always the PATIENT\'s side. The patient\'s upper right is quadrant 1. Never',
     "   flip to the viewer's point of view.",
-    '4. Never do calendar arithmetic. Report the deadline as it was said, using due.kind.',
+    '3. Never do calendar arithmetic. Report the deadline as it was said, using due.kind.',
     '   If no deadline was mentioned, use due.kind = "none".',
-    '5. Copy the exact spoken words for each tooth into "spoken", so the clinician can see',
+    '4. Copy the exact spoken words for each tooth into "spoken", so the clinician can see',
     '   what was heard.',
-    '6. If you are unsure about a value, use null. A missing field is recoverable; a wrong',
+    '5. If you are unsure about a value, use null. A missing field is recoverable; a wrong',
     '   one is not.',
-    '7. A tooth number spoken WITHOUT a quadrant ("دندون دو", "tooth two") does not identify',
-    '   a tooth — four teeth carry that position. Still report it: set "position" and leave',
-    '   "arch" and "side" null. Never pick a quadrant that was not said.',
+    '',
+    'TOOTH NUMBERS',
+    'A number the clinician says for a tooth IS that tooth\'s FDI code. Put it in "fdi" as',
+    'two digits. FDI is built from the two digits:',
+    "  first digit  = quadrant, from the PATIENT's own point of view —",
+    '                 1 upper right, 2 upper left, 3 lower left, 4 lower right.',
+    '                 (5-8 are those same four quadrants in primary/deciduous teeth.)',
+    '  second digit = position from the midline — 1 central incisor ... 8 third molar.',
+    'So 26 is the upper left first molar, and 47 is the lower right second molar.',
+    '',
+    '- Use "arch" + "side" + "position" only when the tooth is DESCRIBED rather than',
+    '  numbered ("upper right six" -> arch "upper", side "patient_right", position 6).',
+    '- A single digit is a position, never an FDI code. If a single digit is said with no',
+    '  quadrant words at all, set "position" and leave "arch" and "side" null. Never pick a',
+    '  quadrant that was not said.',
+    '- If a number is given AND the quadrant is spelled out as well, still use "fdi".',
+    '- Not every number is a tooth. Dates, counts and quantities ("two teeth", "the 26th")',
+    '  are not teeth, and must never appear in the teeth list.',
     '',
     localeNote,
     '',

backend/src/modules/voice/extraction.wire.ts

@@ -21,7 +21,7 @@ import { WEEKDAYS } from './voice.types';
 
 export type WireToothIntent = {
   spoken: string;
-  /** Two-digit FDI code, only when the speaker genuinely used FDI notation. */
+  /** The two-digit FDI code the clinician spoke; null when the tooth was described. */
   fdi: string | null;
   arch: 'upper' | 'lower' | null;
   side: 'patient_right' | 'patient_left' | null;
@@ -66,7 +66,8 @@ const TOOTH_SCHEMA = {
     fdi: {
       type: ['string', 'null'],
       description:
-        'Two-digit FDI code ONLY if the speaker used FDI notation. Otherwise null.',
+        'The two-digit FDI code the clinician said for this tooth, e.g. "26". Null only ' +
+        'when the tooth was described in words instead of numbered.',
     },
     arch: { type: ['string', 'null'], enum: ['upper', 'lower', null] },
     side: {
@@ -76,7 +77,8 @@ const TOOTH_SCHEMA = {
     },
     position: {
       type: ['integer', 'null'],
-      description: '1 = central incisor … 8 = third molar.',
+      description:
+        'Position from the midline: 1 = central incisor … 8 = third molar. Never an FDI code.',
     },
   },
 } as const;