diff --git a/TODO.md b/TODO.md
deleted file mode 100644
index d47e83e45e..0000000000
--- a/TODO.md
+++ /dev/null
@@ -1,149 +0,0 @@
-# TODO: Remaining Parser and Explain Issues
-
-## Current State
-
-- **Tests passing:** ~6,066 (88.9%)
-- **Tests skipped:** ~758 (11.1%)
-- **Parser errors:** 7 remaining
-
-## Recently Fixed (Latest Session)
-
-### Lexer Improvements
-- ✅ Dollar-quoted strings (`$$...$$`)
-- ✅ Hex P notation floats (`0x123p4`, `-0x1P1023`)
-- ✅ Backtick escaping (`` `ta``ble` ``)
-- ✅ BOM (byte order mark) character handling
-- ✅ Dollar signs in identifiers (`$alias$name$`)
-
-### Parser Improvements
-- ✅ SYSTEM DROP FORMAT SCHEMA CACHE
-- ✅ EXPLAIN AST options (`EXPLAIN AST optimize=0 SELECT ...`)
-- ✅ WITH scalar expression without alias (`WITH 1 SELECT 1`)
-- ✅ DROP USER with @ hostname (`test_user@localhost`, `test_user@'192.168.23.15'`)
-- ✅ KEY keyword as implicit alias (`view(select 'foo.com' key)`)
-- ✅ Complex UNION with parentheses (`((SELECT 1) UNION ALL SELECT 2)`)
-
-## Previously Fixed (parser layer)
-
-- ✅ SELECT ALL syntax (`SELECT ALL 'a'`)
-- ✅ FILTER clause on aggregate functions (`argMax() FILTER(WHERE ...)`)
-- ✅ DROP SETTINGS PROFILE (`DROP SETTINGS PROFILE IF EXISTS ...`)
-- ✅ CREATE NAMED COLLECTION (`CREATE NAMED COLLECTION ... AS ...`)
-- ✅ WITH column AS alias syntax (`WITH number AS k SELECT k`)
-- ✅ SHOW TABLES NOT LIKE (`SHOW TABLES NOT LIKE '%'`)
-- ✅ SHOW CREATE QUOTA (`SHOW CREATE QUOTA default`)
-- ✅ LIMIT BY with second LIMIT (`LIMIT 1 BY * LIMIT 1`)
-- ✅ WITH TOTALS HAVING clause (`SELECT count() WITH TOTALS HAVING x != 0`)
-- ✅ COLLATE in column definitions (`varchar(255) COLLATE binary NOT NULL`)
-- ✅ SETTINGS with keyword assignments (`SETTINGS limit=5`)
-- ✅ TTL GROUP BY SET clause (`TTL d + interval 1 second GROUP BY x SET y = max(y)`)
-- ✅ DROP ROW POLICY ON wildcard (`DROP ROW POLICY ... ON default.*`)
-- ✅ INSERT FROM INFILE COMPRESSION (`FROM INFILE '...' COMPRESSION 'gz'`)
-- ✅ FROM before SELECT syntax (`FROM numbers(1) SELECT number`)
-- ✅ Parenthesized SELECT at statement level (`(SELECT 1)`)
-- ✅ EXISTS table syntax (`EXISTS db.table`)
-- ✅ DROP TABLE FORMAT (`DROP TABLE IF EXISTS t FORMAT Null`)
-
-## Previously Fixed (explain layer)
-
-- ✅ TableJoin output - removed join type keywords
-- ✅ Table function aliases (e.g., `remote('127.1') AS t1`)
-- ✅ Table identifier aliases (e.g., `system.one AS xxx`)
-- ✅ Array/tuple cast formatting for `::` syntax
-- ✅ SETTINGS placement with FORMAT clause
-- ✅ Concat operator `||` flattening into single `concat` function
-- ✅ Window function (OVER clause) support
-- ✅ Float literal formatting
-- ✅ Aliased expression handling for binary/unary/function/identifier
-- ✅ PARTITION BY support in CREATE TABLE
-- ✅ Server error message stripping from expected output
-- ✅ DROP TABLE with multiple tables (e.g., `DROP TABLE t1, t2, t3`)
-- ✅ Negative integer/float literals (e.g., `-1` → `Literal Int64_-1`)
-- ✅ Empty tuple in ORDER BY (e.g., `ORDER BY ()` → `Function tuple` with empty `ExpressionList`)
-- ✅ String escape handling (lexer now unescapes `\'`, `\\`, `\n`, `\t`, `\0`, etc.)
-
-## Remaining Parser Issues (7 total)
-
-### Multi-line SQL (Test Framework Limitation)
-These are valid SQL split across multiple lines. Our test framework only reads the first line:
-- Incomplete CASE expressions (`SELECT CASE number`, `SELECT CASE`, `SELECT "number", CASE "number"`)
-
-### QUALIFY Clause with ^ Operator
-Window function filtering with caret operator:
-```sql
-SELECT '{}'::JSON x QUALIFY x.^c0 = 1;
-```
-
-### Parenthesized ALTER
-Multiple ALTER operations in parentheses:
-```sql
-ALTER TABLE t22 (DELETE WHERE ...), (MODIFY SETTING ...), (UPDATE ... WHERE ...);
-```
-
-### INSERT with JSON Data
-JSON data after FORMAT clause:
-```sql
-INSERT INTO FUNCTION null() SELECT * FROM input('x Int') ... FORMAT JSONEachRow {"x": 1};
-```
-
-### EXCEPT in Nested Expressions
-`* EXCEPT` within nested function calls:
-```sql
-SELECT untuple((expr, * EXCEPT b));
-```
-
-## Parser Issues (High Priority)
-
-### CREATE TABLE with INDEX Clause
-```sql
-CREATE TABLE t (x Array(String), INDEX idx1 x TYPE bloom_filter(0.025)) ENGINE=MergeTree;
-```
-
-### SETTINGS Inside Function Arguments
-```sql
-SELECT * FROM icebergS3(s3_conn, filename='test', SETTINGS key='value');
-```
-
-### CREATE TABLE with Column TTL
-```sql
-CREATE TABLE t (c Int TTL expr()) ENGINE=MergeTree;
-```
-
-## Parser Issues (Medium Priority)
-
-### CREATE DICTIONARY
-```sql
-CREATE DICTIONARY d0 (c1 UInt64) PRIMARY KEY c1 LAYOUT(FLAT()) SOURCE(...);
-```
-
-### QUALIFY Clause
-```sql
-SELECT x QUALIFY row_number() OVER () = 1;
-```
-
-### GROUPING SETS
-```sql
-SELECT ... GROUP BY GROUPING SETS ((a), (b));
-```
-
-### CREATE TABLE ... AS SELECT
-```sql
-CREATE TABLE src ENGINE=Memory AS SELECT 1;
-```
-
-## Testing Notes
-
-Run tests with timeout:
-```bash
-go test ./parser -timeout 5s -v
-```
-
-Count test results:
-```bash
-go test ./parser -v 2>&1 | grep -E 'PASS:|SKIP:' | wc -l
-```
-
-View parser failures:
-```bash
-go test ./parser -v 2>&1 | grep "TODO: Parser does not yet support" | head -20
-```
diff --git a/parser/testdata/README.md b/parser/testdata/README.md
new file mode 100644
index 0000000000..a782a6fc7f
--- /dev/null
+++ b/parser/testdata/README.md
@@ -0,0 +1,11 @@
+# Test Data
+
+The `query.sql` files in this directory are sourced from the [ClickHouse](https://github.com/ClickHouse/ClickHouse) repository's test suite.
+
+## License
+
+The `query.sql` files are licensed under the [Apache License 2.0](https://www.apache.org/licenses/LICENSE-2.0), the same license as ClickHouse.
+
+The `explain.txt` and `explain_*.txt` files contain output generated by running ClickHouse's `EXPLAIN AST` command on the corresponding queries.
+
+All other files in this repository are subject to the repository's main license.