fix(rag): bind claim-leading for/in conditions in the high-risk trigger check (S1c follow-up)

docs/branch-review-records/ed2853a1fe7ad33b3ef164093f54fa8df20452c2f8e144ffa1546bb7603c142e.record.md

@@ -0,0 +1 @@
+| 2026-08-17 | claude/s1c-trigger-condition-first-4pb1at | 18a535cde83de776d1e3873385e220c3e307b02e | S1c follow-up: claim-leading for/in condition binding in highRiskTriggerTokens (protected RAG surface, tightening only) | PR #2065 open; digit-free population mis-bind closed fail-first; merge after S1c canary; own post-merge canary pair owner-approved | vitest rag-claim-support 160/160; eval:rag:offline 616/616 zero flips; verify:pr-local heavy failed:(none); check:production-readiness offline provider gaps only |

src/lib/rag/rag-claim-support.ts

@@ -166,6 +166,11 @@ function highRiskTriggerTokens(value: string) {
   const triggerPatterns = [
     /\b(?:when|whenever|if|unless|during|after|before)\b\s*([^,;.!?]+?)(?=\s*,|\s+\b(?:administer|avoid|cease|continue|discontinue|escalate|give|prescribe|start|stop|use|withhold)\b|[;.!?]|$)/gi,
     /\b(?:administer|avoid|cease|continue|discontinue|escalate|give|prescribe|start|stop|use|withhold)\b[^,;.!?]{0,80}?\bfor\b\s*([^,;.!?]+?)(?=\s+\bfor\b|\s*,|[;.!?]|$)/gi,
+    // Condition-first phrasing: a claim-leading "For <population>, <directive> …"
+    // or "In <state>, …" binds its condition exactly like when/if phrasing —
+    // previously this shape extracted no tokens, so the condition never had to
+    // appear in the supporting segment (S1c follow-up).
+    /^\s*(?:for|in)\s+([^,;.!?]{1,60}?)\s*,/gi,
   ];
   for (const pattern of triggerPatterns) {
     for (const match of value.matchAll(pattern)) {

tests/rag-claim-support.test.ts

@@ -285,6 +285,54 @@ describe("deterministic claim support", () => {
     ).toBe(false);
   });
 
+  it("binds a claim-leading population condition to the supporting segment (condition-first trigger)", () => {
+    // "For elderly patients, …" previously extracted no trigger tokens, so an
+    // atom-free neighbouring bullet that merely mentions the population could
+    // lend its topics and let the adult dose be mis-bound to the elderly claim.
+    // (A digit-bearing population phrase like "over 65 years" is already caught
+    // by the atom-free-neighbour rule; this pins the digit-free phrasing.)
+    const adultDoseWithPopulationProse = source(
+      "adult-dose-population-prose",
+      [
+        "• The usual oral starting dose for adults is 500 mg nocte.",
+        "• Elderly patients require cautious dose titration.",
+      ].join("\n"),
+      { title: "Lithium Clinical Guideline(EMHS)", file_name: "Lithium Clinical Guideline(EMHS).pdf" },
+    );
+
+    expect(
+      sourceDirectlySupportsAnswerText(
+        "For elderly patients, start lithium at 500 mg nocte.",
+        adultDoseWithPopulationProse,
+      ),
+    ).toBe(false);
+  });
+
+  it("keeps supporting a faithful condition-first restatement whose segment covers the condition", () => {
+    const emhs = source(
+      "emhs-lithium-condition-first",
+      [
+        "• The usual oral starting dose for adults is 500 mg nocte and for patients over 65 years it",
+        "is 250 mg nocte.",
+      ].join("\n"),
+      { title: "Lithium Clinical Guideline(EMHS)", file_name: "Lithium Clinical Guideline(EMHS).pdf" },
+    );
+
+    expect(sourceDirectlySupportsAnswerText("For patients over 65 years, start lithium at 250 mg nocte.", emhs)).toBe(
+      true,
+    );
+  });
+
+  it("binds a claim-leading in-condition the same way", () => {
+    const renal = source("renal-monitoring", "Monitor lithium levels closely in renal impairment.");
+    const hepatic = source("hepatic-monitoring", "Monitor lithium levels closely in hepatic impairment.");
+
+    expect(sourceDirectlySupportsAnswerText("In renal impairment, monitor lithium levels closely.", renal)).toBe(true);
+    expect(sourceDirectlySupportsAnswerText("In renal impairment, monitor lithium levels closely.", hepatic)).toBe(
+      false,
+    );
+  });
+
   it("keeps a wrapped escalation recipient in the directly supporting source segment", () => {
     const wrappedRule = source(
       "wrapped-escalation-rule",