Adding clang format and lint

.clang-format

@@ -0,0 +1,20 @@
+---
+Language: Cpp
+BasedOnStyle: Google
+Standard: c++11
+ColumnLimit: 120
+IndentWidth: 4
+ContinuationIndentWidth: 4
+TabWidth: 4
+UseTab: Never
+AccessModifierOffset: -4
+AllowShortFunctionsOnASingleLine: Empty
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLoopsOnASingleLine: false
+BreakBeforeBraces: Attach
+DerivePointerAlignment: false
+PointerAlignment: Left
+SortIncludes: CaseSensitive
+IncludeBlocks: Regroup
+NamespaceIndentation: None
+...

.clang-tidy

@@ -0,0 +1,24 @@
+---
+Checks: >
+  -*,
+  bugprone-*,
+  clang-analyzer-*,
+  performance-*,
+  portability-*,
+  readability-braces-around-statements,
+  readability-const-return-type,
+  readability-container-size-empty,
+  readability-duplicate-include,
+  readability-misleading-indentation,
+  readability-redundant-member-init,
+  readability-redundant-string-cstr,
+  readability-redundant-string-init,
+  readability-simplify-boolean-expr,
+  readability-static-accessed-through-instance
+WarningsAsErrors: ''
+HeaderFilterRegex: '(^|.*/)(include|src|tests)/.*'
+FormatStyle: file
+CheckOptions:
+  - key: readability-braces-around-statements.ShortStatementLines
+    value: '1'
+...

CONTRIBUTING.md

@@ -0,0 +1,55 @@
+# Contributing
+
+## Code style
+
+This project uses LLVM tooling for formatting and lightweight linting:
+
+- `clang-format` reads `.clang-format`.
+- `clang-tidy` reads `.clang-tidy`.
+
+The formatting style is based on Google C++ style with a 4-space indent and a
+120-column limit. New and modified C++ code should follow the local naming
+patterns already used by the public API:
+
+- types and public API classes: `PascalCase`
+- public member functions: `PascalCase`
+- free functions used as internal helpers: `PascalCase` when matching existing
+  code, otherwise descriptive lower-case names are preferred for new private
+  helpers
+- variables, data members, and parameters: `snake_case`
+- private data members: trailing underscore, for example `db_`
+- constants and enum values: existing project style, for example `kText`
+- macros: `UPPER_SNAKE_CASE`
+
+Do not reformat vendored third-party sources:
+
+- `src/sqlite3.c`
+- `src/internal/sqlite3.h`
+- `src/internal/date.h`
+
+## Formatting changed files
+
+Run `clang-format` only on project-owned C++ files that you changed:
+
+```console
+clang-format -i include/database.h src/database.cc tests/database_test.cc
+```
+
+To inspect formatting without modifying files:
+
+```console
+clang-format --dry-run --Werror include/database.h src/database.cc tests/database_test.cc
+```
+
+## Linting
+
+After configuring CMake with compile commands enabled, run `clang-tidy` on the
+files you changed:
+
+```console
+cmake -S . -B build -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
+clang-tidy src/database.cc -p build
+```
+
+Keep lint fixes focused on the code touched by the current change. Avoid broad
+style-only rewrites unless the change is explicitly scoped as a formatting PR.

README.md

@@ -19,6 +19,7 @@ A C++ wrapper for SQLite that provides compile-time checked CRUD operations for
 - [Raw SQL](#raw-sql)
 - [Build instructions](#build-instructions)
 - [Dependencies](#dependencies)
+- [Contributing](#contributing)
 
 ## Motivation
 
@@ -391,3 +392,8 @@ You can also open the generated `build/sqlite-cpp-reflection.sln` in Visual Stud
 - A C++11-compatible compiler
 - GoogleTest for tests, fetched by CMake
 - SQLite, vendored in `src/sqlite3.c` and `src/internal/sqlite3.h`
+
+## Contributing
+
+Formatting and linting rules are documented in [CONTRIBUTING.md](CONTRIBUTING.md). The repository includes
+`.clang-format` and `.clang-tidy` so contributors can format and lint changed C++ files consistently.