fix(render): clamp child span bounds to parent in buildSpanTree

When a child entity's span extends past its parent (e.g. the last
quantity in a credit card number where `dot` consumes a trailing
period), the node's rendering bounds are now clamped to the parent's
end. The entity data itself is unchanged — callbacks still see the
original start/end — only the tree position is tightened so text is
not duplicated or lost.

Fixes: last number group in CC/SSN missing from annotated output.

Author: ClaudiuCeia

src/render.ts

@@ -109,24 +109,21 @@ export function buildSpanTree(
       stack.pop();
     }
 
-    // Pop parents that only partially contain this entity (one-sided overlap).
-    // Full containment (start >= parent.start AND end <= parent.end) → child.
-    // Partial overlap (extends past parent) → independent, try a higher parent.
-    while (
-      stack.length > 1 &&
-      e.end > stack[stack.length - 1].end
-    ) {
-      stack.pop();
-    }
-
     const parent = stack[stack.length - 1];
 
     // Skip if this entity starts before the parent
     if (e.start < parent.start) continue;
 
+    // Clamp rendering bounds to the parent. The entity data is unchanged —
+    // only the tree node position is tightened so text isn't duplicated.
+    // Example: quantity "4242." [18,23] inside credit_card [3,22]
+    //   → node renders [18,22], callback still sees entity.end === 23.
+    const clampedEnd = Math.min(e.end, parent.end);
+    if (clampedEnd <= e.start) continue;
+
     const node: SpanNode = {
       start: e.start,
-      end: e.end,
+      end: clampedEnd,
       entity: e,
       children: [],
     };

tests/render.test.ts

@@ -1,5 +1,6 @@
 import { assertEquals } from "@std/assert";
 import {
+  CreditCard,
   Duckling,
   Email,
   PIIParsers,
@@ -110,6 +111,21 @@ Deno.test("render: nested children text is passed pre-rendered", () => {
   assertEquals(ssnCall!.children, "[quantity]-[quantity]-[quantity]");
 });
 
+Deno.test("render: CC with trailing dot — all four groups rendered inside parent", () => {
+  // The `dot` combinator in the last quantity consumes the trailing ".",
+  // making the child span extend past the CC parent. buildSpanTree clamps
+  // the child's rendering bounds to the parent so all four groups appear
+  // and the "." falls outside the CC span.
+  const result = Duckling([Quantity.parser, CreditCard.parser]).render(
+    "CC 4242 4242 4242 4242.",
+    ({ entity, children }) => `<${entity.kind}>${children}</${entity.kind}>`,
+  );
+  assertEquals(
+    result,
+    "CC <credit_card><quantity>4242</quantity> <quantity>4242</quantity> <quantity>4242</quantity> <quantity>4242</quantity></credit_card>.",
+  );
+});
+
 // ── Edge cases ──────────────────────────────────────────────────────
 
 Deno.test("render: empty input", () => {