[Makisuo]

Adds a property-based fuzzer for the query builder under tests/fuzz/ (fast-check). The rest of this stack fixes what it found, one bug per PR.

Oracles (none of them trust the builder):

• Literal round-trip (literals.fuzz.test.ts): a random value of 25 column types reaches the database as a reference row (JSON, or IEEE bits for Float64) and through the builder, as a comparison literal and as a SELECT-list param. Both must decode back to the value. Strings lean on quotes, backslashes, __PARAM_, $1, NUL and odd Unicode.
• Queries vs a reference model (queries.fuzz.test.ts): random plans (joins, nested AND/OR/NOT, LIKE/BETWEEN/IN, grouping, having, ordering, paging, subqueries) run on the core fixture on Postgres (PGlite) and on ClickHouse under both join_use_nulls, and must match model.ts, a JS evaluator with SQL three-valued logic. A plan reporting single-tenant must have read one org's rows.
• Compile properties (compile.fuzz.test.ts, no database): valid plans compile deterministically, leak no undefined/NaN/__PARAM_, and number Postgres placeholders correctly; any JS value in a value position is refused with a QueryBuilderError, never thrown.

Workflow: bun run test runs a few-second budget; bun run fuzz with FUZZ_SCALE/FUZZ_RUNS for soaks. A failure prints the shrunk input, its SQL, the server reply and a FUZZ_SEED=… FUZZ_PATH=… replay command; pin it in regressions.ts. Open bugs live in known-issues.ts with a reason and a matcher; FUZZ_STRICT=<id> re-enables one. Documented in docs/testing.md.

Verification: bun run typecheck, bun run test; 50× soak against ClickHouse 25.8 + PGlite (30k queries vs the model, 30k compiled plans, 50k hostile values, ~100k literal round-trips) green with the found bugs recorded as known issues. Locally string-predicates fails on 25.8 (hasAllTokens is newer), as on main.

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Stack (merge bottom-up):

1. test(fuzz): property-based fuzzer for the query builder #39 test(fuzz): property-based fuzzer for the query builder
2. fix(clickhouse): write number literals that read back exactly #40 fix(clickhouse): write number literals that read back exactly
3. fix: parenthesise an arithmetic expression passed as an argument #41 fix: parenthesise an arithmetic expression passed as an argument
4. fix: fail with QueryBuilderError instead of throwing on unusable values #42 fix: fail with QueryBuilderError instead of throwing on unusable values
5. fix: bare select() over a subquery or union selects every alias #43 fix: bare select() over a subquery or union selects every alias
6. fix(clickhouse): cast array and map comparison literals to the column type #44 fix(clickhouse): cast array and map comparison literals to the column type
7. fix(postgres): type the two placeholders Postgres would mistype #45 fix(postgres): type the two placeholders Postgres would mistype

🤖 Generated with Claude Code

Summary by CodeRabbit

• Testing
  • Added randomized checks for query generation, compilation, and literal-value handling across PostgreSQL and ClickHouse.
  • Tests compare database results with expected outcomes and check query behavior, including tenant scoping.
  • Added controls for run length, replaying failures, and strict handling of known issues.
• Documentation
  • Added guidance for running fuzz tests and replaying failures.

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• tests/fuzz/harness.ts

📝 Walkthrough

The pull request adds a property-based fuzz testing framework for ClickHouse and PostgreSQL. It generates literals and query plans, compiles and runs queries, and compares outcomes with reference checks. It also adds commands, run controls, pinned regression inputs, known-issue handling, and testing documentation.

Changes: Cross-dialect fuzz testing

Layer / File(s)	Summary
Plan generators and reference model tests/core-cases.ts, tests/fuzz/plan.ts, tests/fuzz/values.ts, tests/fuzz/model.ts	The shared fixture rows are exported. New generators create typed plans and literal values. The reference model evaluates expressions, conditions, joins, aggregates, sorting, and paging for PostgreSQL and ClickHouse.
Query construction and database runners tests/fuzz/build.ts, tests/fuzz/contexts.ts, tests/fuzz/db.ts	Generated plans are translated into query-builder calls and compiled for the selected dialect. Database runners execute queries against PGlite or ClickHouse and return tagged outcomes.
Property harness and regression inputs tests/fuzz/harness.ts, tests/fuzz/known-issues.ts, tests/fuzz/regressions.ts	The harness configures runs, executes pinned and generated inputs, and reports shrunk failures with replay commands. Known-issue predicates classify selected inputs, and pinned plans, literals, and hostile values supply regression cases.
Literal, plan, and compilation properties tests/fuzz/literals.fuzz.test.ts, tests/fuzz/queries.fuzz.test.ts, tests/fuzz/compile.fuzz.test.ts	The suites check literal round trips, compare database query results with the reference model, and test compilation determinism, parameter handling, tenant scope, and hostile values.
Fuzz command and documentation package.json, docs/testing.md	The package adds a fuzz script and fast-check development dependency. The testing guide describes fuzz suites, run controls, failure replay, pinned regressions, and strict mode.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Other

Sequence Diagram(s)

sequenceDiagram
  participant QueryProperty
  participant matchesModel
  participant evaluate
  participant compilePlan
  participant run
  QueryProperty->>matchesModel: generated plan and target
  matchesModel->>evaluate: evaluate plan against reference data
  matchesModel->>compilePlan: compile plan for target dialect
  matchesModel->>run: execute compiled query
  run-->>matchesModel: decoded rows or database outcome
  matchesModel->>matchesModel: compare rows and check tenant scope

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Possibly related issues

• clickhouse-http: string parameters are sent unescaped, so newlines fail and backslashes change the value #38 — The fuzz suites exercise literal values in comparison and SELECT-parameter paths, which overlap with the reported ClickHouse handling of bound strings and arrays. The pull request adds tests for these paths but does not state that it fixes the reported behavior.

Merge Risk: 🔵 Low · up to 8e83a

This PR adds fuzz tests and a fuzz command with no production behavior change. The printed replay command can match no tests for property names with parentheses or brackets, which makes reproducing a fuzz failure harder. It is safe to merge, and escaping the name would fix it.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely identifies the main change: adding a property-based fuzzing test suite for the query builder.
Docstring Coverage		No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 13 files. (2 skipped: 2 unsupported.)

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Actionable comments posted: 1

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

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Inline comments:
Review comments at @tests/fuzz/harness.ts:
- Line 144: Update the replay-command construction in the `replay` assignment to
escape regex metacharacters in `name` before passing it to Vitest’s `-t` option,
and single-quote the escaped pattern so shell metacharacters are not expanded.

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📒 Files selected for processing: 15

• docs/testing.md
• package.json
• tests/core-cases.ts
• tests/fuzz/build.ts
• tests/fuzz/compile.fuzz.test.ts
• tests/fuzz/contexts.ts
• tests/fuzz/db.ts
• tests/fuzz/harness.ts
• tests/fuzz/known-issues.ts
• tests/fuzz/literals.fuzz.test.ts
• tests/fuzz/model.ts
• tests/fuzz/plan.ts
• tests/fuzz/queries.fuzz.test.ts
• tests/fuzz/regressions.ts
• tests/fuzz/values.ts

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