fix: match PDF-imported patients by member ID when DOB is missing on record

MassHealth eligibility lookups via the AI chatbot only matched existing
patients on memberId+DOB, so patients imported from PDF extraction (which
have a member ID but no stored birthday) were treated as new/unknown even
though they already exist in the system.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

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

@@ -79,6 +79,9 @@ Intents:
                           Insurance abbreviations are: mh, masshealth, bcbs, cca, dentaquest — anything else is a patient name
 - eligibility_by_id     : user provides a SINGLE member ID and date of birth (no patient name)
                           e.g. "check masshealth for 100xxxx, 10/10/1988"
+                          e.g. "100xxxx 10/10/1988" or "100xxxx, 10/10/1988" — a bare member ID + DOB with
+                            NO verb and NO insurance keyword is STILL eligibility_by_id (default to MassHealth,
+                            omit insuranceHint). Do NOT classify this as "general".
                           ALSO use this when user wants to check eligibility AND schedule/add an appointment on a date
                           e.g. "check mh for 100xxxx, 10/10/1988 and schedule on 4/10/2026"
                           e.g. "check mh for 100xxxx, 10/10/1988 and make appointment on 5/1/2026"
@@ -219,6 +222,20 @@ Rules:
 
 // ─── Classifier ───────────────────────────────────────────────────────────────
 
+// Deterministic fast-path for a bare "memberId DOB" (or "DOB memberId") message with
+// nothing else in it — e.g. "100232102531 4/27/1999" or "100232102531, 4/27/1999".
+// Bypasses the LLM entirely so this always resolves to eligibility_by_id, since some
+// providers hedge/refuse structured output on a bare digit string that looks like an SSN.
+function parseBareIdDob(message: string): { memberId: string; dob: string } | null {
+  const text = message.trim();
+  const dobPattern = /(\d{1,2}[\/\-]\d{1,2}[\/\-]\d{4})/;
+  const idThenDob = text.match(new RegExp(`^([A-Za-z0-9]{3,})[\\s,]+${dobPattern.source}$`));
+  if (idThenDob) return { memberId: idThenDob[1]!, dob: idThenDob[2]!.replace(/-/g, "/") };
+  const dobThenId = text.match(new RegExp(`^${dobPattern.source}[\\s,]+([A-Za-z0-9]{3,})$`));
+  if (dobThenId) return { memberId: dobThenId[2]!, dob: dobThenId[1]!.replace(/-/g, "/") };
+  return null;
+}
+
 export async function classifyInternalChat(
   message: string,
   apiKey: string,
@@ -234,6 +251,16 @@ export async function classifyInternalChat(
       "I can search for a patient, check eligibility, run check & claim, schedule appointments, or navigate to claims or appointments.",
   };
 
+  const bare = parseBareIdDob(message);
+  if (bare) {
+    return {
+      intent: "eligibility_by_id",
+      memberId: bare.memberId,
+      dob: bare.dob,
+      fallbackReply: `Checking eligibility for Member ID ${bare.memberId}...`,
+    };
+  }
+
   if (!apiKey) return fallback;
 
   // Prefer the client's local date (avoids UTC midnight rollover for US timezones)