@@ -0,0 +1,5 @@
+---
+"@hyperdx/common-utils": patch
+---
+
+fix: support text index on lower(Body) with no preprocessor
@@ -1177,6 +1177,161 @@ describe('CustomSchemaSQLSerializerV2 - text indices', () => {
     expect(sql).toBe("((hasToken(lower(Body), lower('foo'))))");
   });
 
+  describe('lower(Body) text index (no preprocessor)', () => {
+    it('should use hasAllTokens(lower(Body), lower(...)) when index expression is lower(Body)', async () => {
+      metadata.getSkipIndices = jest.fn().mockResolvedValue([
+        {
+          name: 'idx_lower_body',
+          type: 'text',
+          typeFull: "text(tokenizer = 'splitByNonAlpha')",
+          expression: 'lower(Body)',
+          granularity: '8',
+        },
+      ]);
+
+      const serializer = new CustomSchemaSQLSerializerV2({
+        metadata,
+        databaseName,
+        tableName,
+        connectionId,
+        implicitColumnExpression: 'Body',
+      });
+
+      const builder = new SearchQueryBuilder('Foo', serializer);
+      const sql = await builder.build();
+
+      expect(sql).toBe("((hasAllTokens(lower(Body), lower('Foo'))))");
+    });
+
+    it('should use hasAllTokens(lower(Body), lower(...)) for multi-token terms', async () => {
+      metadata.getSkipIndices = jest.fn().mockResolvedValue([
+        {
+          name: 'idx_lower_body',
+          type: 'text',
+          typeFull: "text(tokenizer = 'splitByNonAlpha')",
+          expression: 'lower(Body)',
+          granularity: '8',
+        },
+      ]);
+
+      const serializer = new CustomSchemaSQLSerializerV2({
+        metadata,
+        databaseName,
+        tableName,
+        connectionId,
+        implicitColumnExpression: 'Body',
+      });
+
+      const builder = new SearchQueryBuilder('"Foo Bar"', serializer);
+      const sql = await builder.build();
+
+      expect(sql).toContain("hasAllTokens(lower(Body), lower('Foo Bar'))");
+      expect(sql).toContain("(lower(Body) LIKE lower('%Foo Bar%'))");
+    });
+
+    it('should handle negated searches with lower(Body) index', async () => {
+      metadata.getSkipIndices = jest.fn().mockResolvedValue([
+        {
+          name: 'idx_lower_body',
+          type: 'text',
+          typeFull: "text(tokenizer = 'splitByNonAlpha')",
+          expression: 'lower(Body)',
+          granularity: '8',
+        },
+      ]);
+
+      const serializer = new CustomSchemaSQLSerializerV2({
+        metadata,
+        databaseName,
+        tableName,
+        connectionId,
+        implicitColumnExpression: 'Body',
+      });
+
+      const builder = new SearchQueryBuilder('-Foo', serializer);
+      const sql = await builder.build();
+
+      expect(sql).toBe("((NOT hasAllTokens(lower(Body), lower('Foo'))))");
+    });
+
+    it('should NOT use lower() when index is directly on Body', async () => {
+      metadata.getSkipIndices = jest.fn().mockResolvedValue([
+        {
+          name: 'idx_body_text',
+          type: 'text',
+          typeFull: 'text(tokenizer=splitByNonAlpha)',
+          expression: 'Body',
+          granularity: '8',
+        },
+      ]);
+
+      const serializer = new CustomSchemaSQLSerializerV2({
+        metadata,
+        databaseName,
+        tableName,
+        connectionId,
+        implicitColumnExpression: 'Body',
+      });
+
+      const builder = new SearchQueryBuilder('Foo', serializer);
+      const sql = await builder.build();
+
+      expect(sql).toBe("((hasAllTokens(Body, 'Foo')))");
+    });
+
+    it('should batch tokens with lower() when index is on lower(Body)', async () => {
+      metadata.getSkipIndices = jest.fn().mockResolvedValue([
+        {
+          name: 'idx_lower_body',
+          type: 'text',
+          typeFull: "text(tokenizer = 'splitByNonAlpha')",
+          expression: 'lower(Body)',
+          granularity: '8',
+        },
+      ]);
+
+      const serializer = new CustomSchemaSQLSerializerV2({
+        metadata,
+        databaseName,
+        tableName,
+        connectionId,
+        implicitColumnExpression: 'Body',
+      });
+
+      const builder = new SearchQueryBuilder('FOO NOT BAR BAZ', serializer);
+      const sql = await builder.build();
+
+      expect(sql).toContain("hasAllTokens(lower(Body), lower('FOO'))");
+      expect(sql).toContain("NOT (hasAllTokens(lower(Body), lower('BAR')))");
+      expect(sql).toContain("hasAllTokens(lower(Body), lower('BAZ'))");
+    });
+
+    it('should detect LOWER(Body) case-insensitively', async () => {
+      metadata.getSkipIndices = jest.fn().mockResolvedValue([
+        {
+          name: 'idx_lower_body',
+          type: 'text',
+          typeFull: "text(tokenizer = 'splitByNonAlpha')",
+          expression: 'LOWER(Body)',
+          granularity: '8',
+        },
+      ]);
+
+      const serializer = new CustomSchemaSQLSerializerV2({
+        metadata,
+        databaseName,
+        tableName,
+        connectionId,
+        implicitColumnExpression: 'Body',
+      });
+
+      const builder = new SearchQueryBuilder('foo', serializer);
+      const sql = await builder.build();
+
+      expect(sql).toBe("((hasAllTokens(lower(Body), lower('foo'))))");
+    });
+  });
+
   describe('useTextIndexForImplicitColumn source preference', () => {
     it('Auto preserves the existing detection behavior when a text index is found', async () => {
       metadata.getSkipIndices = jest.fn().mockResolvedValue([
@@ -1312,6 +1467,30 @@ describe('CustomSchemaSQLSerializerV2 - text indices', () => {
       expect(sql).toBe("((hasAll(tokens(lower(Body)), tokens(lower('foo')))))");
     });
 
+    it('Enabled uses lower() wrapping when a lower(Body) text index exists', async () => {
+      metadata.getSkipIndices = jest.fn().mockResolvedValue([
+        {
+          name: 'idx_lower_body',
+          type: 'text',
+          typeFull: "text(tokenizer = 'splitByNonAlpha')",
+          expression: 'lower(Body)',
+          granularity: '8',
+        },
+      ]);
+
+      const serializer = new CustomSchemaSQLSerializerV2({
+        metadata,
+        databaseName,
+        tableName,
+        connectionId,
+        implicitColumnExpression: 'Body',
+        useTextIndexForImplicitColumn: UseTextIndex.Enabled,
+      });
+
+      const sql = await new SearchQueryBuilder('foo', serializer).build();
+      expect(sql).toBe("((hasAllTokens(lower(Body), lower('foo'))))");
+    });
+
     it('Enabled with a multi-token term still falls back to LIKE when separators exist', async () => {
       metadata.getSkipIndices = jest.fn().mockResolvedValue([]);
 
 
@@ -1273,20 +1273,28 @@ export class CustomSchemaSQLSerializerV2 extends SQLSerializer {
         //   - enabled: force hasAllTokens(), even if no text index is detected
         //   - disabled: skip the text-index branch entirely
         let useHasAllTokens = false;
+        let textIndexHasLower = false;
         if (this.useTextIndexForImplicitColumn === UseTextIndex.Enabled) {
           useHasAllTokens = true;
+          const textIndexResult = await this.findTextIndex(column);
+          if (textIndexResult) {
+            textIndexHasLower = textIndexResult.indexHasLower;
+          }
         } else if (this.useTextIndexForImplicitColumn === UseTextIndex.Auto) {
           // Note: We check that enable_full_text_index = 1, otherwise hasAllTokens() errors
           const isTextIndexEnabled = await this.enableTextIndexPromise;
-          const textIndex = isTextIndexEnabled
+          const textIndexResult = isTextIndexEnabled
             ? await this.findTextIndex(column)
             : undefined;
 
-          if (textIndex) {
-            const tokenizer = parseTokenizerFromTextIndex(textIndex);
+          if (textIndexResult) {
+            const tokenizer = parseTokenizerFromTextIndex(
+              textIndexResult.index,
+            );
             // HDX-3259: Support other tokenizers by overriding tokenizeTerm, termHasSeparators, and batching logic
             if (tokenizer?.type === 'splitByNonAlpha') {
               useHasAllTokens = true;
+              textIndexHasLower = textIndexResult.indexHasLower;
             }
           }
         }
@@ -1295,13 +1303,24 @@ export class CustomSchemaSQLSerializerV2 extends SQLSerializer {
           const tokens = this.tokenizeTerm(term);
           const hasSeparators = this.termHasSeparators(term);
 
+          // When the text index is on lower(column), we must pass lower(column)
+          // as the first argument and wrap the tokens in lower() to match.
+          const hasAllTokensColumn = textIndexHasLower
+            ? `lower(${column})`
+            : column;
+
           // Batch tokens to avoid exceeding hasAllTokens limit (64)
           const tokenBatches = chunk(tokens, HAS_ALL_TOKENS_CHUNK_SIZE);
           const hasAllTokensExpressions = tokenBatches.map(batch =>
-            SqlString.format(`hasAllTokens(?, ?)`, [
-              SqlString.raw(column),
-              batch.join(' '),
-            ]),
+            textIndexHasLower
+              ? SqlString.format(`hasAllTokens(?, lower(?))`, [
+                  SqlString.raw(hasAllTokensColumn),
+                  batch.join(' '),
+                ])
+              : SqlString.format(`hasAllTokens(?, ?)`, [
+                  SqlString.raw(hasAllTokensColumn),
+                  batch.join(' '),
+                ]),
           );
 
           if (hasSeparators || tokenBatches.length > 1) {
@@ -1324,7 +1343,9 @@ export class CustomSchemaSQLSerializerV2 extends SQLSerializer {
         const bloomIndex = await this.findBloomFilterTokensIndex(column);
 
         if (bloomIndex.found) {
-          const indexHasLower = /\blower\s*\(/.test(bloomIndex.indexExpression);
+          const indexHasLower = this.isLowerExpression(
+            bloomIndex.indexExpression,
+          );
           const termTokensExpression = indexHasLower
             ? SqlString.format('tokens(lower(?))', [term])
             : SqlString.format('tokens(?)', [term]);
@@ -1531,21 +1552,36 @@ export class CustomSchemaSQLSerializerV2 extends SQLSerializer {
     // throw new Error(`Column not found: ${field}`);
   }
 
+  private isLowerExpression(expr: string): boolean {
+    return /\blower\s*\(/i.test(expr);
+  }
+
   private async findTextIndex(
     columnExpression: string,
-  ): Promise<SkipIndexMetadata | undefined> {
+  ): Promise<{ index: SkipIndexMetadata; indexHasLower: boolean } | undefined> {
     const skipIndices = await this.skipIndicesPromise;
 
     if (!skipIndices || skipIndices.length === 0) {
       return undefined;
     }
 
-    // Note: Text index expressions should not be wrapped in tokens() or preprocessing functions like lower().
-    return skipIndices.find(
+    const idx = skipIndices.find(
       idx =>
         idx.type === 'text' &&
         this.indexCoversColumn(idx.expression, columnExpression),
     );
+
+    if (!idx) {
+      return undefined;
+    }
+
+    const normalizedExpr = normalizeChExpression(idx.expression);
+    const normalizedCol = normalizeChExpression(columnExpression);
+    const indexHasLower =
+      normalizedExpr !== normalizedCol &&
+      this.isLowerExpression(idx.expression);
+
+    return { index: idx, indexHasLower };
   }
 
   /**
-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"@hyperdx/common-utils": patch
 +---
++
 +fix: support text index on lower(Body) with no preprocessor