From cf36425b0aa150b425e11a6677618f7c9a3b0e5a Mon Sep 17 00:00:00 2001
From: t8y2 <t8y2@users.noreply.github.com>
Date: Tue, 22 Sep 2026 15:57:23 +0800
Subject: [PATCH] fix(completion): bound statement block scans to active SQL

Refs: #5997
---
 .../sql/sqlCompletion.performance.spec.ts     | 43 +++++++++++++++++++
 apps/desktop/src/lib/sql/sqlCompletion.ts     | 12 +++---
 2 files changed, 50 insertions(+), 5 deletions(-)
 create mode 100644 apps/desktop/src/lib/__tests__/sql/sqlCompletion.performance.spec.ts

diff --git a/apps/desktop/src/lib/__tests__/sql/sqlCompletion.performance.spec.ts b/apps/desktop/src/lib/__tests__/sql/sqlCompletion.performance.spec.ts
new file mode 100644
index 0000000000..d206ce499f
--- /dev/null
+++ b/apps/desktop/src/lib/__tests__/sql/sqlCompletion.performance.spec.ts
@@ -0,0 +1,43 @@
+import { PostgreSQL, sql } from "@codemirror/lang-sql";
+import { ensureSyntaxTree } from "@codemirror/language";
+import { EditorState } from "@codemirror/state";
+import { describe, expect, it, vi } from "vitest";
+import { getSqlCompletionContext } from "@/lib/sql/sqlCompletion";
+
+describe("SQL completion statement-local scanning", () => {
+  it.each(["\n", " "])("does not split unrelated statements separated by %j before the active syntax-tree window", (separator) => {
+    const prefix = `SELECT id FROM previous_table;${separator}`.repeat(2_000);
+    const activeStatement = "SELECT customer_ FROM current_table";
+    const suffix = ";\n" + "SELECT id FROM later_table;\n".repeat(2_000);
+    const document = prefix + activeStatement + suffix;
+    const cursor = prefix.length + activeStatement.indexOf(" FROM");
+    const state = EditorState.create({ doc: document, extensions: [sql({ dialect: PostgreSQL })] });
+    ensureSyntaxTree(state, document.length, 5_000);
+    const scannedLengths: number[] = [];
+    const originalSplit = String.prototype.split;
+    const splitSpy = vi.spyOn(String.prototype, "split").mockImplementation(function (this: string, separator, limit) {
+      if (separator instanceof RegExp && separator.source === "\\r?\\n") scannedLengths.push(this.length);
+      return originalSplit.call(this, separator, limit);
+    });
+
+    try {
+      const context = getSqlCompletionContext(document, cursor, { databaseType: "postgres", editorState: state });
+      expect(context.referencedTables.map((table) => table.name)).toEqual(["current_table"]);
+      expect(scannedLengths.length).toBeGreaterThan(0);
+      expect(Math.max(...scannedLengths)).toBeLessThanOrEqual(activeStatement.length);
+    } finally {
+      splitSpy.mockRestore();
+    }
+  });
+
+  it("preserves CRLF offsets when selecting a semicolon-free statement block", () => {
+    const document = "SELECT id FROM previous_table;\r\nSELECT id FROM first_table\r\nSELECT customer_ FROM current_table\r\nSELECT id FROM later_table";
+    const cursor = document.indexOf("customer_") + "customer_".length;
+    const state = EditorState.create({ doc: document, extensions: [sql({ dialect: PostgreSQL })] });
+    ensureSyntaxTree(state, document.length, 5_000);
+
+    const context = getSqlCompletionContext(document, cursor, { databaseType: "postgres", editorState: state });
+    expect(context.prefix).toBe("customer_");
+    expect(context.referencedTables.map((table) => table.name)).toEqual(["current_table"]);
+  });
+});
diff --git a/apps/desktop/src/lib/sql/sqlCompletion.ts b/apps/desktop/src/lib/sql/sqlCompletion.ts
index 3ded3d5232..f70cc9fa41 100644
--- a/apps/desktop/src/lib/sql/sqlCompletion.ts
+++ b/apps/desktop/src/lib/sql/sqlCompletion.ts
@@ -2211,10 +2211,10 @@ function activeSqlCompletionStatementSpan(sql: string, cursor: number, options:
 
 function currentSqlLikeLineBlockSpan(sql: string, cursor: number, activeStatementSpan: SqlSemanticSpan): SqlSemanticSpan | null {
   const safeCursor = Math.max(0, Math.min(cursor, sql.length));
-  const beforeCursor = sql.slice(0, safeCursor);
+  const beforeCursor = sql.slice(activeStatementSpan.start, safeCursor);
   const lines = beforeCursor.split(/\r?\n/);
   let start: number | null = null;
-  let offset = 0;
+  let offset = activeStatementSpan.start;
 
   for (const line of lines) {
     const trimmed = line.trimStart();
@@ -2223,14 +2223,16 @@ function currentSqlLikeLineBlockSpan(sql: string, cursor: number, activeStatemen
       if (/^(select|with)\b/i.test(trimmed)) start = offset + indentation;
       if (/^(get|post|put|delete|patch|head)\s+\//i.test(trimmed)) start = null;
     }
-    offset += line.length + 1;
+    offset += line.length;
+    offset += sql[offset] === "\r" && sql[offset + 1] === "\n" ? 2 : 1;
   }
 
   if (start == null) return null;
   if (activeStatementSpan.start > start) return null;
 
-  const blockEnd = currentLineBlockEnd(sql, safeCursor, start);
-  return { start, end: blockEnd == null ? activeStatementSpan.end : Math.min(activeStatementSpan.end, blockEnd) };
+  const statementSql = sql.slice(activeStatementSpan.start, activeStatementSpan.end);
+  const blockEnd = currentLineBlockEnd(statementSql, safeCursor - activeStatementSpan.start, start - activeStatementSpan.start);
+  return { start, end: blockEnd == null ? activeStatementSpan.end : Math.min(activeStatementSpan.end, activeStatementSpan.start + blockEnd) };
 }
 
 // Equal-length masking of string/comment characters, so parenthesis depth and