From 2127072a5828caea9efe78692877c5b68a30ba0c Mon Sep 17 00:00:00 2001
From: Joshua Horton <joshua_horton@sil.org>
Date: Wed, 28 Jan 2026 09:49:24 -0600
Subject: [PATCH] change(web): add .edgeKey for use + validation of complex
 .split cases

Build-bot: skip build
Test-bot: skip
---
 .../main/correction/search-quotient-spur.ts   | 21 ++++++-
 .../search-quotient-spur.tests.ts             | 61 +++++++++++++++++++
 2 files changed, 81 insertions(+), 1 deletion(-)

diff --git a/web/src/engine/predictive-text/worker-thread/src/main/correction/search-quotient-spur.ts b/web/src/engine/predictive-text/worker-thread/src/main/correction/search-quotient-spur.ts
index 7a69c2bd99d..d32cfa8becb 100644
--- a/web/src/engine/predictive-text/worker-thread/src/main/correction/search-quotient-spur.ts
+++ b/web/src/engine/predictive-text/worker-thread/src/main/correction/search-quotient-spur.ts
@@ -476,4 +476,23 @@ export abstract class SearchQuotientSpur implements SearchQuotientNode {
 
     return components.join('+');
   }
-}
\ No newline at end of file
+
+  /**
+   * Provides a unique hash-style string corresponding to the edge represented
+   * by this graph spur.
+   *
+   * This is designed for use in two cases:
+   * 1. At runtime - plays a role in simplification of results for .split
+   *    operations with SearchQuotientCluster ancestry, which may cause
+   *    quotient-paths that diverge and reconverge during recursion
+   *    - Specifically, this property assists detection of duplicate instances
+   *      during 'diverged' states, allowing reconvergence to be handled.
+   * 2. In unit tests - validating that splits with SearchQuotientCluster
+   *    ancestry properly handle quotient-path variance in unit tests.
+   */
+  get edgeKey(): string {
+    const inputSrc = this.inputSource;
+    const segment = inputSrc.segment;
+    return `E${inputSrc.subsetId}:${segment.start}${segment.end !== undefined ? `-${segment.end}` : ''}`;
+  }
+}
diff --git a/web/src/test/auto/headless/engine/predictive-text/worker-thread/correction-search/search-quotient-spur.tests.ts b/web/src/test/auto/headless/engine/predictive-text/worker-thread/correction-search/search-quotient-spur.tests.ts
index b026f7eb9bf..a8a32fa8b4f 100644
--- a/web/src/test/auto/headless/engine/predictive-text/worker-thread/correction-search/search-quotient-spur.tests.ts
+++ b/web/src/test/auto/headless/engine/predictive-text/worker-thread/correction-search/search-quotient-spur.tests.ts
@@ -322,6 +322,67 @@ describe('SearchQuotientSpur', () => {
     });
   });
 
+  describe('.edgeKey', () => {
+    it('changes when input source subset IDs differ', () => {
+      const root = new LegacyQuotientRoot(testModel);
+
+      const {distributions} = buildSimplePathSplitFixture();
+      const inputSrc = {
+        segment: {
+          transitionId: distributions[0][0].sample.id,
+          start: 0
+        },
+        subsetId: generateSubsetId(),
+        bestProbFromSet: distributions[0][0].p
+      };
+
+      const spur1 = new LegacyQuotientSpur(root, distributions[0], {
+        ...inputSrc,
+        subsetId: generateSubsetId()
+      });
+      const spur2 = new LegacyQuotientSpur(root, distributions[0], {
+        ...inputSrc,
+        subsetId: generateSubsetId()
+      });
+
+      assert.notEqual(spur1.edgeKey, spur2.edgeKey);
+    });
+
+    it('changes when different parts of the same input source are used', () => {
+      const root = new LegacyQuotientRoot(testModel);
+
+      const {distributions} = buildSimplePathSplitFixture();
+      const inputSrc = {
+        segment: {
+          transitionId: distributions[0][0].sample.id,
+          start: 0
+        },
+        subsetId: generateSubsetId(),
+        bestProbFromSet: distributions[0][0].p
+      };
+
+      const spur1 = new LegacyQuotientSpur(root, distributions[0], inputSrc);
+      const spur2 = new LegacyQuotientSpur(root, distributions[0], {
+        ...inputSrc,
+        segment: {
+          ...inputSrc.segment,
+          end: 1
+        }
+      });
+      const spur3 = new LegacyQuotientSpur(root, distributions[0], {
+        ...inputSrc,
+        segment: {
+          ...inputSrc.segment,
+          start: inputSrc.segment.start + 1
+        }
+      });
+
+      assert.notEqual(spur1.edgeKey, spur2.edgeKey);
+      assert.notEqual(spur2.edgeKey, spur3.edgeKey);
+      assert.notEqual(spur3.edgeKey, spur1.edgeKey);
+    });
+  });
+
   describe('split()', () => {
     describe(`on token comprised of single-char transforms:  [crt][ae][nr][t]`, () => {
       const runSplit = (splitIndex: number) => {