[ty] Allow overriding rules for specific files (#18648)

Cargo.lock

@@ -1952,6 +1952,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7d31b8b7a99f71bdff4235faf9ce9eada0ad3562c8fbeb7d607d9f41a6ec569d"
 dependencies = [
  "indexmap",
+ "serde",
 ]
 
 [[package]]
@@ -3949,6 +3950,7 @@ dependencies = [
  "globset",
  "insta",
  "notify",
+ "ordermap",
  "pep440_rs",
  "rayon",
  "regex",

crates/ruff_db/src/diagnostic/mod.rs

@@ -668,6 +668,73 @@ pub enum DiagnosticId {
 
     /// A glob pattern doesn't follow the expected syntax.
     InvalidGlob,
+
+    /// An `include` glob without any patterns.
+    ///
+    /// ## Why is this bad?
+    /// An `include` glob without any patterns won't match any files. This is probably a mistake and
+    /// either the `include` should be removed or a pattern should be added.
+    ///
+    /// ## Example
+    /// ```toml
+    /// [src]
+    /// include = []
+    /// ```
+    ///
+    /// Use instead:
+    ///
+    /// ```toml
+    /// [src]
+    /// include = ["src"]
+    /// ```
+    ///
+    /// or remove the `include` option.
+    EmptyInclude,
+
+    /// An override configuration is unnecessary because it applies to all files.
+    ///
+    /// ## Why is this bad?
+    /// An overrides section that applies to all files is probably a mistake and can be rolled-up into the root configuration.
+    ///
+    /// ## Example
+    /// ```toml
+    /// [[overrides]]
+    /// [overrides.rules]
+    /// unused-reference = "ignore"
+    /// ```
+    ///
+    /// Use instead:
+    ///
+    /// ```toml
+    /// [rules]
+    /// unused-reference = "ignore"
+    /// ```
+    ///
+    /// or
+    ///
+    /// ```toml
+    /// [[overrides]]
+    /// include = ["test"]
+    ///
+    /// [overrides.rules]
+    /// unused-reference = "ignore"
+    /// ```
+    UnnecessaryOverridesSection,
+
+    /// An `overrides` section in the configuration that doesn't contain any overrides.
+    ///
+    /// ## Why is this bad?
+    /// An `overrides` section without any configuration overrides is probably a mistake.
+    /// It is either a leftover after removing overrides, or a user forgot to add any overrides,
+    /// or used an incorrect syntax to do so (e.g. used `rules` instead of `overrides.rules`).
+    ///
+    /// ## Example
+    /// ```toml
+    /// [[overrides]]
+    /// include = ["test"]
+    /// # no `[overrides.rules]`
+    /// ```
+    UselessOverridesSection,
 }
 
 impl DiagnosticId {
@@ -703,6 +770,9 @@ impl DiagnosticId {
             DiagnosticId::RevealedType => "revealed-type",
             DiagnosticId::UnknownRule => "unknown-rule",
             DiagnosticId::InvalidGlob => "invalid-glob",
+            DiagnosticId::EmptyInclude => "empty-include",
+            DiagnosticId::UnnecessaryOverridesSection => "unnecessary-overrides-section",
+            DiagnosticId::UselessOverridesSection => "useless-overrides-section",
         }
     }
 

crates/ruff_db/src/lib.rs

@@ -59,6 +59,13 @@ pub fn max_parallelism() -> NonZeroUsize {
         })
 }
 
+/// Trait for types that can provide Rust documentation.
+///
+/// Use `derive(RustDoc)` to automatically implement this trait for types that have a static string documentation.
+pub trait RustDoc {
+    fn rust_doc() -> &'static str;
+}
+
 #[cfg(test)]
 mod tests {
     use std::sync::{Arc, Mutex};

crates/ruff_graph/src/db.rs

@@ -92,7 +92,7 @@ impl Db for ModuleDb {
         !file.path(self).is_vendored_path()
     }
 
-    fn rule_selection(&self) -> &RuleSelection {
+    fn rule_selection(&self, _file: File) -> &RuleSelection {
         &self.rule_selection
     }
 

crates/ruff_macros/src/lib.rs

@@ -16,6 +16,7 @@ mod map_codes;
 mod newtype_index;
 mod rule_code_prefix;
 mod rule_namespace;
+mod rust_doc;
 mod violation_metadata;
 
 #[proc_macro_derive(OptionsMetadata, attributes(option, doc, option_group))]
@@ -27,6 +28,15 @@ pub fn derive_options_metadata(input: TokenStream) -> TokenStream {
         .into()
 }
 
+#[proc_macro_derive(RustDoc)]
+pub fn derive_rust_doc(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+
+    rust_doc::derive_impl(input)
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
+}
+
 #[proc_macro_derive(CombineOptions)]
 pub fn derive_combine_options(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);

crates/ruff_macros/src/rust_doc.rs

@@ -0,0 +1,62 @@
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{Attribute, DeriveInput, Error, Lit, LitStr, Meta};
+
+pub(crate) fn derive_impl(input: DeriveInput) -> syn::Result<TokenStream> {
+    let docs = get_docs(&input.attrs)?;
+
+    let name = input.ident;
+
+    let (impl_generics, ty_generics, where_clause) = &input.generics.split_for_impl();
+
+    Ok(quote! {
+        #[automatically_derived]
+        impl #impl_generics ruff_db::RustDoc for #name #ty_generics #where_clause {
+            fn rust_doc() -> &'static str {
+                #docs
+            }
+        }
+    })
+}
+/// Collect all doc comment attributes into a string
+fn get_docs(attrs: &[Attribute]) -> syn::Result<String> {
+    let mut explanation = String::new();
+    for attr in attrs {
+        if attr.path().is_ident("doc") {
+            if let Some(lit) = parse_attr(["doc"], attr) {
+                let value = lit.value();
+                // `/// ` adds
+                let line = value.strip_prefix(' ').unwrap_or(&value);
+                explanation.push_str(line);
+                explanation.push('\n');
+            } else {
+                return Err(Error::new_spanned(attr, "unimplemented doc comment style"));
+            }
+        }
+    }
+    Ok(explanation)
+}
+
+fn parse_attr<'a, const LEN: usize>(
+    path: [&'static str; LEN],
+    attr: &'a Attribute,
+) -> Option<&'a LitStr> {
+    if let Meta::NameValue(name_value) = &attr.meta {
+        let path_idents = name_value
+            .path
+            .segments
+            .iter()
+            .map(|segment| &segment.ident);
+
+        if path_idents.eq(path) {
+            if let syn::Expr::Lit(syn::ExprLit {
+                lit: Lit::Str(lit), ..
+            }) = &name_value.value
+            {
+                return Some(lit);
+            }
+        }
+    }
+
+    None
+}

crates/ty/docs/configuration.md

@@ -151,6 +151,116 @@ typeshed = "/path/to/custom/typeshed"
 
 ---
 
+## `overrides`
+
+Configuration override that applies to specific files based on glob patterns.
+
+An override allows you to apply different rule configurations to specific
+files or directories. Multiple overrides can match the same file, with
+later overrides take precedence.
+
+### Precedence
+
+- Later overrides in the array take precedence over earlier ones
+- Override rules take precedence over global rules for matching files
+
+### Examples
+
+```toml
+# Relax rules for test files
+[[tool.ty.overrides]]
+include = ["tests/**", "**/test_*.py"]
+
+[tool.ty.overrides.rules]
+possibly-unresolved-reference = "warn"
+
+# Ignore generated files but still check important ones
+[[tool.ty.overrides]]
+include = ["generated/**"]
+exclude = ["generated/important.py"]
+
+[tool.ty.overrides.rules]
+possibly-unresolved-reference = "ignore"
+```
+
+
+#### `exclude`
+
+A list of file and directory patterns to exclude from this override.
+
+Patterns follow a syntax similar to `.gitignore`.
+Exclude patterns take precedence over include patterns within the same override.
+
+If not specified, defaults to `[]` (excludes no files).
+
+**Default value**: `null`
+
+**Type**: `list[str]`
+
+**Example usage** (`pyproject.toml`):
+
+```toml
+[[tool.ty.overrides]]
+exclude = [
+    "generated",
+    "*.proto",
+    "tests/fixtures/**",
+    "!tests/fixtures/important.py"  # Include this one file
+]
+```
+
+---
+
+#### `include`
+
+A list of file and directory patterns to include for this override.
+
+The `include` option follows a similar syntax to `.gitignore` but reversed:
+Including a file or directory will make it so that it (and its contents)
+are affected by this override.
+
+If not specified, defaults to `["**"]` (matches all files).
+
+**Default value**: `null`
+
+**Type**: `list[str]`
+
+**Example usage** (`pyproject.toml`):
+
+```toml
+[[tool.ty.overrides]]
+include = [
+    "src",
+    "tests",
+]
+```
+
+---
+
+#### `rules`
+
+Rule overrides for files matching the include/exclude patterns.
+
+These rules will be merged with the global rules, with override rules
+taking precedence for matching files. You can set rules to different
+severity levels or disable them entirely.
+
+**Default value**: `{...}`
+
+**Type**: `dict[RuleName, "ignore" | "warn" | "error"]`
+
+**Example usage** (`pyproject.toml`):
+
+```toml
+[[tool.ty.overrides]]
+include = ["src"]
+
+[tool.ty.overrides.rules]
+possibly-unresolved-reference = "ignore"
+```
+
+---
+
 ## `src`
 
 #### `exclude`
@@ -214,6 +324,45 @@ exclude = [
 
 ---
 
+#### `include`
+
+A list of files and directories to check. The `include` option
+follows a similar syntax to `.gitignore` but reversed:
+Including a file or directory will make it so that it (and its contents)
+are type checked.
+
+- `./src/` matches only a directory
+- `./src` matches both files and directories
+- `src` matches a file or directory named `src`
+- `*` matches any (possibly empty) sequence of characters (except `/`).
+- `**` matches zero or more path components.
+  This sequence **must** form a single path component, so both `**a` and `b**` are invalid and will result in an error.
+  A sequence of more than two consecutive `*` characters is also invalid.
+- `?` matches any single character except `/`
+- `[abc]` matches any character inside the brackets. Character sequences can also specify ranges of characters, as ordered by Unicode,
+  so e.g. `[0-9]` specifies any character between `0` and `9` inclusive. An unclosed bracket is invalid.
+
+Unlike `exclude`, all paths are anchored relative to the project root (`src` only
+matches `<project_root>/src` and not `<project_root>/test/src`).
+
+`exclude` takes precedence over `include`.
+
+**Default value**: `null`
+
+**Type**: `list[str]`
+
+**Example usage** (`pyproject.toml`):
+
+```toml
+[tool.ty.src]
+include = [
+    "src",
+    "tests",
+]
+```
+
+---
+
 #### `respect-ignore-files`
 
 Whether to automatically exclude files that are ignored by `.ignore`,

crates/ty/src/args.rs

@@ -205,14 +205,17 @@ impl CheckCommand {
             src: Some(SrcOptions {
                 respect_ignore_files,
                 exclude: self.exclude.map(|excludes| {
-                    excludes
+                    RangedValue::cli(
-                        .iter()
+                        excludes
-                        .map(|exclude| RelativeExcludePattern::cli(exclude))
+                            .iter()
-                        .collect()
+                            .map(|exclude| RelativeExcludePattern::cli(exclude))
+                            .collect(),
+                    )
                 }),
                 ..SrcOptions::default()
             }),
             rules,
+            ..Options::default()
         };
         // Merge with options passed in via --config
         options.combine(self.config.into_options().unwrap_or_default())

crates/ty/tests/cli/config_option.rs

@@ -128,7 +128,7 @@ fn cli_config_args_later_overrides_earlier() -> anyhow::Result<()> {
 #[test]
 fn cli_config_args_invalid_option() -> anyhow::Result<()> {
     let case = CliTest::with_file("test.py", r"print(1)")?;
-    assert_cmd_snapshot!(case.command().arg("--config").arg("bad-option=true"), @r###"
+    assert_cmd_snapshot!(case.command().arg("--config").arg("bad-option=true"), @r"
     success: false
     exit_code: 2
     ----- stdout -----
@@ -138,13 +138,13 @@ fn cli_config_args_invalid_option() -> anyhow::Result<()> {
       |
     1 | bad-option=true
       | ^^^^^^^^^^
-    unknown field `bad-option`, expected one of `environment`, `src`, `rules`, `terminal`
+    unknown field `bad-option`, expected one of `environment`, `src`, `rules`, `terminal`, `overrides`
 
 
     Usage: ty <COMMAND>
 
     For more information, try '--help'.
-    "###);
+    ");
 
     Ok(())
 }

crates/ty/tests/cli/file_selection.rs

@@ -639,7 +639,7 @@ fn invalid_include_pattern() -> anyhow::Result<()> {
     2 | [src]
     3 | include = [
     4 |     "src/**test/"
-      |     ^^^^^^^^^^^^^ Too many stars at position 5 in glob: `src/**test/`
+      |     ^^^^^^^^^^^^^ Too many stars at position 5
     5 | ]
       |
     "#);
@@ -676,7 +676,7 @@ fn invalid_include_pattern_concise_output() -> anyhow::Result<()> {
     ----- stderr -----
     WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
     ty failed
-      Cause: error[invalid-glob] ty.toml:4:5: Invalid include pattern: Too many stars at position 5 in glob: `src/**test/`
+      Cause: error[invalid-glob] ty.toml:4:5: Invalid include pattern: Too many stars at position 5
     ");
 
     Ok(())
@@ -717,7 +717,7 @@ fn invalid_exclude_pattern() -> anyhow::Result<()> {
     2 | [src]
     3 | exclude = [
     4 |     "../src"
-      |     ^^^^^^^^ The parent directory operator (`..`) at position 1 is not allowed in glob: `../src`
+      |     ^^^^^^^^ The parent directory operator (`..`) at position 1 is not allowed
     5 | ]
       |
     "#);

crates/ty/tests/cli/rule_selection.rs

@@ -290,3 +290,613 @@ fn cli_unknown_rules() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+/// Basic override functionality: override rules for specific files
+#[test]
+fn overrides_basic() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "error"
+            unresolved-reference = "error"
+
+            [[tool.ty.overrides]]
+            include = ["tests/**"]
+
+            [tool.ty.overrides.rules]
+            division-by-zero = "warn"
+            unresolved-reference = "ignore"
+            "#,
+        ),
+        (
+            "main.py",
+            r#"
+            y = 4 / 0  # division-by-zero: error (global)
+            x = 1
+            prin(x)    # unresolved-reference: error (global)
+            "#,
+        ),
+        (
+            "tests/test_main.py",
+            r#"
+            y = 4 / 0  # division-by-zero: warn (override)
+            x = 1
+            prin(x)    # unresolved-reference: ignore (override)
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    error[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> main.py:2:5
+      |
+    2 | y = 4 / 0  # division-by-zero: error (global)
+      |     ^^^^^
+    3 | x = 1
+    4 | prin(x)    # unresolved-reference: error (global)
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    error[unresolved-reference]: Name `prin` used when not defined
+     --> main.py:4:1
+      |
+    2 | y = 4 / 0  # division-by-zero: error (global)
+    3 | x = 1
+    4 | prin(x)    # unresolved-reference: error (global)
+      | ^^^^
+      |
+    info: rule `unresolved-reference` was selected in the configuration file
+
+    warning[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> tests/test_main.py:2:5
+      |
+    2 | y = 4 / 0  # division-by-zero: warn (override)
+      |     ^^^^^
+    3 | x = 1
+    4 | prin(x)    # unresolved-reference: ignore (override)
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    Found 3 diagnostics
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    "###);
+
+    Ok(())
+}
+
+/// Multiple overrides: later overrides take precedence
+#[test]
+fn overrides_precedence() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "error"
+
+            # First override: all test files
+            [[tool.ty.overrides]]
+            include = ["tests/**"]
+            [tool.ty.overrides.rules]
+            division-by-zero = "warn"
+
+            # Second override: specific test file (takes precedence)
+            [[tool.ty.overrides]]
+            include = ["tests/important.py"]
+            [tool.ty.overrides.rules]
+            division-by-zero = "ignore"
+            "#,
+        ),
+        (
+            "tests/test_main.py",
+            r#"
+            y = 4 / 0  # division-by-zero: warn (first override)
+            "#,
+        ),
+        (
+            "tests/important.py",
+            r#"
+            y = 4 / 0  # division-by-zero: ignore (second override)
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    warning[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> tests/test_main.py:2:5
+      |
+    2 | y = 4 / 0  # division-by-zero: warn (first override)
+      |     ^^^^^
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    Found 1 diagnostic
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    ");
+
+    Ok(())
+}
+
+/// Override with exclude patterns
+#[test]
+fn overrides_exclude() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "error"
+
+            [[tool.ty.overrides]]
+            include = ["tests/**"]
+            exclude = ["tests/important.py"]
+            [tool.ty.overrides.rules]
+            division-by-zero = "warn"
+            "#,
+        ),
+        (
+            "tests/test_main.py",
+            r#"
+            y = 4 / 0  # division-by-zero: warn (override applies)
+            "#,
+        ),
+        (
+            "tests/important.py",
+            r#"
+            y = 4 / 0  # division-by-zero: error (override excluded)
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    error[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> tests/important.py:2:5
+      |
+    2 | y = 4 / 0  # division-by-zero: error (override excluded)
+      |     ^^^^^
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    warning[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> tests/test_main.py:2:5
+      |
+    2 | y = 4 / 0  # division-by-zero: warn (override applies)
+      |     ^^^^^
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    Found 2 diagnostics
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    ");
+
+    Ok(())
+}
+
+/// Override without rules inherits global rules
+#[test]
+fn overrides_inherit_global() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "warn"
+            unresolved-reference = "error"
+
+            [[tool.ty.overrides]]
+            include = ["tests/**"]
+
+            [tool.ty.overrides.rules]
+            # Override only division-by-zero, unresolved-reference should inherit from global
+            division-by-zero = "ignore"
+            "#,
+        ),
+        (
+            "main.py",
+            r#"
+            y = 4 / 0  # division-by-zero: warn (global)
+            prin(y)    # unresolved-reference: error (global)
+            "#,
+        ),
+        (
+            "tests/test_main.py",
+            r#"
+            y = 4 / 0  # division-by-zero: ignore (overridden)
+            prin(y)    # unresolved-reference: error (inherited from global)
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r#"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    warning[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> main.py:2:5
+      |
+    2 | y = 4 / 0  # division-by-zero: warn (global)
+      |     ^^^^^
+    3 | prin(y)    # unresolved-reference: error (global)
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    error[unresolved-reference]: Name `prin` used when not defined
+     --> main.py:3:1
+      |
+    2 | y = 4 / 0  # division-by-zero: warn (global)
+    3 | prin(y)    # unresolved-reference: error (global)
+      | ^^^^
+      |
+    info: rule `unresolved-reference` was selected in the configuration file
+
+    error[unresolved-reference]: Name `prin` used when not defined
+     --> tests/test_main.py:3:1
+      |
+    2 | y = 4 / 0  # division-by-zero: ignore (overridden)
+    3 | prin(y)    # unresolved-reference: error (inherited from global)
+      | ^^^^
+      |
+    info: rule `unresolved-reference` was selected in the configuration file
+
+    Found 3 diagnostics
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    "#);
+
+    Ok(())
+}
+
+/// ty warns about invalid glob patterns in override include patterns
+#[test]
+fn overrides_invalid_include_glob() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "error"
+
+            [[tool.ty.overrides]]
+            include = ["tests/[invalid"]  # Invalid glob: unclosed bracket
+            [tool.ty.overrides.rules]
+            division-by-zero = "warn"
+            "#,
+        ),
+        (
+            "test.py",
+            r#"
+            y = 4 / 0
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r#"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    ty failed
+      Cause: error[invalid-glob]: Invalid include pattern
+     --> pyproject.toml:6:12
+      |
+    5 | [[tool.ty.overrides]]
+    6 | include = ["tests/[invalid"]  # Invalid glob: unclosed bracket
+      |            ^^^^^^^^^^^^^^^^ unclosed character class; missing ']'
+    7 | [tool.ty.overrides.rules]
+    8 | division-by-zero = "warn"
+      |
+    "#);
+
+    Ok(())
+}
+
+/// ty warns about invalid glob patterns in override exclude patterns
+#[test]
+fn overrides_invalid_exclude_glob() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "error"
+
+            [[tool.ty.overrides]]
+            include = ["tests/**"]
+            exclude = ["***/invalid"]     # Invalid glob: triple asterisk
+            [tool.ty.overrides.rules]
+            division-by-zero = "warn"
+            "#,
+        ),
+        (
+            "test.py",
+            r#"
+            y = 4 / 0
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r#"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    ty failed
+      Cause: error[invalid-glob]: Invalid exclude pattern
+     --> pyproject.toml:7:12
+      |
+    5 | [[tool.ty.overrides]]
+    6 | include = ["tests/**"]
+    7 | exclude = ["***/invalid"]     # Invalid glob: triple asterisk
+      |            ^^^^^^^^^^^^^ Too many stars at position 1
+    8 | [tool.ty.overrides.rules]
+    9 | division-by-zero = "warn"
+      |
+    "#);
+
+    Ok(())
+}
+
+/// ty warns when an overrides section has neither include nor exclude
+#[test]
+fn overrides_missing_include_exclude() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "error"
+
+            [[tool.ty.overrides]]
+            # Missing both include and exclude - should warn
+            [tool.ty.overrides.rules]
+            division-by-zero = "warn"
+            "#,
+        ),
+        (
+            "test.py",
+            r#"
+            y = 4 / 0
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r#"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    warning[unnecessary-overrides-section]: Unnecessary `overrides` section
+     --> pyproject.toml:5:1
+      |
+    3 | division-by-zero = "error"
+    4 |
+    5 | [[tool.ty.overrides]]
+      | ^^^^^^^^^^^^^^^^^^^^^ This overrides section applies to all files
+    6 | # Missing both include and exclude - should warn
+    7 | [tool.ty.overrides.rules]
+      |
+    info: It has no `include` or `exclude` option restricting the files
+    info: Restrict the files by adding a pattern to `include` or `exclude`...
+    info: or remove the `[[overrides]]` section and merge the configuration into the root `[rules]` table if the configuration should apply to all files
+
+    warning[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> test.py:2:5
+      |
+    2 | y = 4 / 0
+      |     ^^^^^
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    Found 2 diagnostics
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    "#);
+
+    Ok(())
+}
+
+/// ty warns when an overrides section has an empty include array
+#[test]
+fn overrides_empty_include() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "error"
+
+            [[tool.ty.overrides]]
+            include = []  # Empty include - won't match any files
+            [tool.ty.overrides.rules]
+            division-by-zero = "warn"
+            "#,
+        ),
+        (
+            "test.py",
+            r#"
+            y = 4 / 0
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r#"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    warning[empty-include]: Empty include matches no files
+     --> pyproject.toml:6:11
+      |
+    5 | [[tool.ty.overrides]]
+    6 | include = []  # Empty include - won't match any files
+      |           ^^ This `include` list is empty
+    7 | [tool.ty.overrides.rules]
+    8 | division-by-zero = "warn"
+      |
+    info: Remove the `include` option to match all files or add a pattern to match specific files
+
+    error[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> test.py:2:5
+      |
+    2 | y = 4 / 0
+      |     ^^^^^
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    Found 2 diagnostics
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    "#);
+
+    Ok(())
+}
+
+/// ty warns when an overrides section has no actual overrides
+#[test]
+fn overrides_no_actual_overrides() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "error"
+
+            [[tool.ty.overrides]]
+            include = ["*.py"]  # Has patterns but no rule overrides
+            # Missing [tool.ty.overrides.rules] section entirely
+            "#,
+        ),
+        (
+            "test.py",
+            r#"
+            y = 4 / 0
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r#"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    warning[useless-overrides-section]: Useless `overrides` section
+     --> pyproject.toml:5:1
+      |
+    3 |   division-by-zero = "error"
+    4 |
+    5 | / [[tool.ty.overrides]]
+    6 | | include = ["*.py"]  # Has patterns but no rule overrides
+      | |__________________^ This overrides section configures no rules
+    7 |   # Missing [tool.ty.overrides.rules] section entirely
+      |
+    info: It has no `rules` table
+    info: Add a `[overrides.rules]` table...
+    info: or remove the `[[overrides]]` section if there's nothing to override
+
+    error[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> test.py:2:5
+      |
+    2 | y = 4 / 0
+      |     ^^^^^
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    Found 2 diagnostics
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    "#);
+
+    Ok(())
+}
+
+/// ty warns about unknown rules specified in an overrides section
+#[test]
+fn overrides_unknown_rules() -> anyhow::Result<()> {
+    let case = CliTest::with_files([
+        (
+            "pyproject.toml",
+            r#"
+            [tool.ty.rules]
+            division-by-zero = "error"
+
+            [[tool.ty.overrides]]
+            include = ["tests/**"]
+
+            [tool.ty.overrides.rules]
+            division-by-zero = "warn"
+            division-by-zer = "error"  # incorrect rule name
+            "#,
+        ),
+        (
+            "main.py",
+            r#"
+            y = 4 / 0
+            "#,
+        ),
+        (
+            "tests/test_main.py",
+            r#"
+            y = 4 / 0
+            "#,
+        ),
+    ])?;
+
+    assert_cmd_snapshot!(case.command(), @r#"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    warning[unknown-rule]: Unknown lint rule `division-by-zer`
+      --> pyproject.toml:10:1
+       |
+     8 | [tool.ty.overrides.rules]
+     9 | division-by-zero = "warn"
+    10 | division-by-zer = "error"  # incorrect rule name
+       | ^^^^^^^^^^^^^^^
+       |
+
+    error[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> main.py:2:5
+      |
+    2 | y = 4 / 0
+      |     ^^^^^
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    warning[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
+     --> tests/test_main.py:2:5
+      |
+    2 | y = 4 / 0
+      |     ^^^^^
+      |
+    info: rule `division-by-zero` was selected in the configuration file
+
+    Found 3 diagnostics
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    "#);
+
+    Ok(())
+}

crates/ty_ide/src/db.rs

@@ -120,7 +120,7 @@ pub(crate) mod tests {
             !file.path(self).is_vendored_path()
         }
 
-        fn rule_selection(&self) -> &RuleSelection {
+        fn rule_selection(&self, _file: File) -> &RuleSelection {
             &self.rule_selection
         }
 

crates/ty_project/Cargo.toml

@@ -30,6 +30,7 @@ crossbeam = { workspace = true }
 globset = { workspace = true }
 notify = { workspace = true }
 pep440_rs = { workspace = true, features = ["version-ranges"] }
+ordermap = { workspace = true, features = ["serde"] }
 rayon = { workspace = true }
 regex = { workspace = true }
 regex-automata = { workspace = true }

crates/ty_project/src/combine.rs

@@ -1,5 +1,6 @@
 use std::{collections::HashMap, hash::BuildHasher};
 
+use ordermap::OrderMap;
 use ruff_db::system::SystemPathBuf;
 use ruff_python_ast::PythonVersion;
 use ty_python_semantic::{PythonPath, PythonPlatform};
@@ -111,6 +112,18 @@ where
     }
 }
 
+impl<K, V, S> Combine for OrderMap<K, V, S>
+where
+    K: Eq + std::hash::Hash,
+    S: BuildHasher,
+{
+    fn combine_with(&mut self, other: Self) {
+        for (k, v) in other {
+            self.entry(k).or_insert(v);
+        }
+    }
+}
+
 /// Implements [`Combine`] for a value that always returns `self` when combined with another value.
 macro_rules! impl_noop_combine {
     ($name:ident) => {
@@ -150,6 +163,7 @@ impl_noop_combine!(String);
 #[cfg(test)]
 mod tests {
     use crate::combine::Combine;
+    use ordermap::OrderMap;
     use std::collections::HashMap;
 
     #[test]
@@ -188,4 +202,24 @@ mod tests {
             ]))
         );
     }
+
+    #[test]
+    fn combine_order_map() {
+        let a: OrderMap<u32, _> = OrderMap::from_iter([(1, "a"), (2, "a"), (3, "a")]);
+        let b: OrderMap<u32, _> = OrderMap::from_iter([(0, "b"), (2, "b"), (5, "b")]);
+
+        assert_eq!(None.combine(Some(b.clone())), Some(b.clone()));
+        assert_eq!(Some(a.clone()).combine(None), Some(a.clone()));
+        assert_eq!(
+            Some(a).combine(Some(b)),
+            // The value from `a` takes precedence
+            Some(OrderMap::from_iter([
+                (1, "a"),
+                (2, "a"),
+                (3, "a"),
+                (0, "b"),
+                (5, "b")
+            ]))
+        );
+    }
 }

crates/ty_project/src/db.rs

@@ -1,6 +1,7 @@
 use std::panic::{AssertUnwindSafe, RefUnwindSafe};
 use std::sync::Arc;
 
+use crate::metadata::settings::file_settings;
 use crate::{DEFAULT_LINT_REGISTRY, DummyReporter};
 use crate::{Project, ProjectMetadata, Reporter};
 use ruff_db::diagnostic::Diagnostic;
@@ -162,8 +163,9 @@ impl SemanticDb for ProjectDatabase {
         project.is_file_open(self, file)
     }
 
-    fn rule_selection(&self) -> &RuleSelection {
+    fn rule_selection(&self, file: File) -> &RuleSelection {
-        self.project().rules(self)
+        let settings = file_settings(self, file);
+        settings.rules(self)
     }
 
     fn lint_registry(&self) -> &LintRegistry {
@@ -340,7 +342,7 @@ pub(crate) mod tests {
             !file.path(self).is_vendored_path()
         }
 
-        fn rule_selection(&self) -> &RuleSelection {
+        fn rule_selection(&self, _file: ruff_db::files::File) -> &RuleSelection {
             self.project().rules(self)
         }
 

crates/ty_project/src/glob.rs

@@ -58,6 +58,12 @@ impl IncludeExcludeFilter {
     }
 }
 
+impl std::fmt::Display for IncludeExcludeFilter {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "include={}, exclude={}", &self.include, &self.exclude)
+    }
+}
+
 #[derive(Copy, Clone, Eq, PartialEq)]
 pub(crate) enum GlobFilterCheckMode {
     /// The paths are checked top-to-bottom and inclusion is determined

crates/ty_project/src/glob/exclude.rs

@@ -6,6 +6,7 @@
 //! * `/src/**` excludes all files and directories inside a directory named `src` but not `src` itself.
 //! * `!src` allows a file or directory named `src` anywhere in the path
 
+use std::fmt::Formatter;
 use std::sync::Arc;
 
 use globset::{Candidate, GlobBuilder, GlobSet, GlobSetBuilder};
@@ -63,6 +64,12 @@ impl ExcludeFilter {
     }
 }
 
+impl std::fmt::Display for ExcludeFilter {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_list().entries(&self.ignore.globs).finish()
+    }
+}
+
 pub(crate) struct ExcludeFilterBuilder {
     ignore: GitignoreBuilder,
 }
@@ -150,8 +157,8 @@ impl Gitignore {
 
 impl std::fmt::Debug for Gitignore {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("Gitignore")
+        f.debug_tuple("Gitignore")
-            .field("globs", &self.globs)
+            .field(&self.globs)
             .finish_non_exhaustive()
     }
 }
@@ -230,13 +237,18 @@ impl GitignoreBuilder {
     /// Adds a gitignore like glob pattern to this builder.
     ///
     /// If the pattern could not be parsed as a glob, then an error is returned.
-    fn add(&mut self, mut pattern: &str) -> Result<&mut GitignoreBuilder, globset::Error> {
+    fn add(
+        &mut self,
+        pattern: &AbsolutePortableGlobPattern,
+    ) -> Result<&mut GitignoreBuilder, globset::Error> {
         let mut glob = IgnoreGlob {
-            original: pattern.to_string(),
+            original: pattern.relative().to_string(),
             is_allow: false,
             is_only_dir: false,
         };
 
+        let mut pattern = pattern.absolute();
+
         // File names starting with `!` are escaped with a backslash. Strip the backslash.
         // This is not a negated pattern!
         if pattern.starts_with("\\!") {

crates/ty_project/src/glob/include.rs

@@ -2,6 +2,7 @@ use globset::{Glob, GlobBuilder, GlobSet, GlobSetBuilder};
 use regex_automata::dfa;
 use regex_automata::dfa::Automaton;
 use ruff_db::system::SystemPath;
+use std::fmt::Formatter;
 use std::path::{MAIN_SEPARATOR, MAIN_SEPARATOR_STR};
 use tracing::warn;
 
@@ -92,12 +93,18 @@ impl IncludeFilter {
 
 impl std::fmt::Debug for IncludeFilter {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("IncludeFilder")
+        f.debug_tuple("IncludeFilter")
-            .field("original_patterns", &self.original_patterns)
+            .field(&self.original_patterns)
             .finish_non_exhaustive()
     }
 }
 
+impl std::fmt::Display for IncludeFilter {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_list().entries(&self.original_patterns).finish()
+    }
+}
+
 impl PartialEq for IncludeFilter {
     fn eq(&self, other: &Self) -> bool {
         self.original_patterns == other.original_patterns
@@ -127,35 +134,35 @@ impl IncludeFilterBuilder {
         &mut self,
         input: &AbsolutePortableGlobPattern,
     ) -> Result<&mut Self, globset::Error> {
-        let mut glob = &**input;
+        let mut glob_pattern = input.absolute();
 
         let mut only_directory = false;
 
         // A pattern ending with a `/` should only match directories. E.g. `src/` only matches directories
         // whereas `src` matches both files and directories.
         // We need to remove the `/` to ensure that a path missing the trailing `/` matches.
-        if let Some(after) = input.strip_suffix('/') {
+        if let Some(after) = glob_pattern.strip_suffix('/') {
             // Escaped `/` or `\` aren't allowed. `portable_glob::parse` will error
             only_directory = true;
-            glob = after;
+            glob_pattern = after;
         }
 
         // If regex ends with `/**`, only push that one glob and regex
         // Otherwise, push two regex, one for `/**` and one for without
-        let glob = GlobBuilder::new(glob)
+        let glob = GlobBuilder::new(glob_pattern)
             .literal_separator(true)
             // No need to support Windows-style paths, so the backslash can be used a escape.
             .backslash_escape(true)
             .build()?;
-        self.original_pattern.push(input.to_string());
+        self.original_pattern.push(input.relative().to_string());
 
         // `lib` is the same as `lib/**`
         // Add a glob that matches `lib` exactly, change the glob to `lib/**`.
-        if input.ends_with("**") {
+        if glob_pattern.ends_with("**") {
             self.push_prefix_regex(&glob);
             self.set.add(glob);
         } else {
-            let prefix_glob = GlobBuilder::new(&format!("{glob}/**"))
+            let prefix_glob = GlobBuilder::new(&format!("{glob_pattern}/**"))
                 .literal_separator(true)
                 // No need to support Windows-style paths, so the backslash can be used a escape.
                 .backslash_escape(true)

crates/ty_project/src/glob/portable.rs

@@ -8,6 +8,7 @@
 //! [Source](https://github.com/astral-sh/uv/blob/main/crates/uv-globfilter/src/portable_glob.rs)
 
 use ruff_db::system::SystemPath;
+use std::error::Error as _;
 use std::ops::Deref;
 use std::{fmt::Write, path::MAIN_SEPARATOR};
 use thiserror::Error;
@@ -65,14 +66,12 @@ impl<'a> PortableGlobPattern<'a> {
                 }
                 if star_run >= 3 {
                     return Err(PortableGlobError::TooManyStars {
-                        glob: glob.to_string(),
                         // We don't update pos for the stars.
                         pos,
                     });
                 } else if star_run == 2 {
                     if chars.peek().is_some_and(|(_, c)| *c != '/') {
                         return Err(PortableGlobError::TooManyStars {
-                            glob: glob.to_string(),
                             // We don't update pos for the stars.
                             pos,
                         });
@@ -83,10 +82,7 @@ impl<'a> PortableGlobPattern<'a> {
                 start_or_slash = false;
             } else if c == '.' {
                 if start_or_slash && matches!(chars.peek(), Some((_, '.'))) {
-                    return Err(PortableGlobError::ParentDirectory {
+                    return Err(PortableGlobError::ParentDirectory { pos });
-                        pos,
-                        glob: glob.to_string(),
-                    });
                 }
                 start_or_slash = false;
             } else if c == '/' {
@@ -99,7 +95,6 @@ impl<'a> PortableGlobPattern<'a> {
                         break;
                     } else {
                         return Err(PortableGlobError::InvalidCharacterRange {
-                            glob: glob.to_string(),
                             pos,
                             invalid: InvalidChar(c),
                         });
@@ -111,24 +106,17 @@ impl<'a> PortableGlobPattern<'a> {
                     Some((pos, '/' | '\\')) => {
                         // For cross-platform compatibility, we don't allow forward slashes or
                         // backslashes to be escaped.
-                        return Err(PortableGlobError::InvalidEscapee {
+                        return Err(PortableGlobError::InvalidEscapee { pos });
-                            glob: glob.to_string(),
-                            pos,
-                        });
                     }
                     Some(_) => {
                         // Escaped character
                     }
                     None => {
-                        return Err(PortableGlobError::TrailingEscape {
+                        return Err(PortableGlobError::TrailingEscape { pos });
-                            glob: glob.to_string(),
-                            pos,
-                        });
                     }
                 }
             } else {
                 return Err(PortableGlobError::InvalidCharacter {
-                    glob: glob.to_string(),
                     pos,
                     invalid: InvalidChar(c),
                 });
@@ -160,12 +148,18 @@ impl<'a> PortableGlobPattern<'a> {
             // Patterns that don't contain any `/`, e.g. `.venv` are unanchored patterns
             // that match anywhere.
             if !self.chars().any(|c| c == '/') {
-                return AbsolutePortableGlobPattern(self.to_string());
+                return AbsolutePortableGlobPattern {
+                    absolute: self.to_string(),
+                    relative: self.pattern.to_string(),
+                };
             }
         }
 
         if pattern.starts_with('/') {
-            return AbsolutePortableGlobPattern(pattern.to_string());
+            return AbsolutePortableGlobPattern {
+                absolute: pattern.to_string(),
+                relative: self.pattern.to_string(),
+            };
         }
 
         let mut rest = pattern;
@@ -206,9 +200,15 @@ impl<'a> PortableGlobPattern<'a> {
         output.push_str(rest);
         if negated {
             // If the pattern is negated, we need to keep the leading `!`.
-            AbsolutePortableGlobPattern(format!("!{output}"))
+            AbsolutePortableGlobPattern {
+                absolute: format!("!{output}"),
+                relative: self.pattern.to_string(),
+            }
         } else {
-            AbsolutePortableGlobPattern(output)
+            AbsolutePortableGlobPattern {
+                absolute: output,
+                relative: self.pattern.to_string(),
+            }
         }
     }
 }
@@ -225,53 +225,48 @@ impl Deref for PortableGlobPattern<'_> {
 ///
 /// E.g., `./src/**` becomes `/root/src/**` when anchored to `/root`.
 #[derive(Debug, Eq, PartialEq, Hash)]
-pub(crate) struct AbsolutePortableGlobPattern(String);
+pub(crate) struct AbsolutePortableGlobPattern {
+    absolute: String,
+    relative: String,
+}
 
-impl Deref for AbsolutePortableGlobPattern {
+impl AbsolutePortableGlobPattern {
-    type Target = str;
+    /// Returns the absolute path of this glob pattern.
+    pub(crate) fn absolute(&self) -> &str {
+        &self.absolute
+    }
 
-    fn deref(&self) -> &Self::Target {
+    /// Returns the relative path of this glob pattern.
-        &self.0
+    pub(crate) fn relative(&self) -> &str {
+        &self.relative
     }
 }
 
 #[derive(Debug, Error)]
 pub(crate) enum PortableGlobError {
     /// Shows the failing glob in the error message.
-    #[error(transparent)]
+    #[error("{desc}", desc=.0.description())]
     GlobError(#[from] globset::Error),
 
-    #[error(
+    #[error("The parent directory operator (`..`) at position {pos} is not allowed")]
-        "The parent directory operator (`..`) at position {pos} is not allowed in glob: `{glob}`"
+    ParentDirectory { pos: usize },
-    )]
-    ParentDirectory { glob: String, pos: usize },
 
     #[error(
-        "Invalid character `{invalid}` at position {pos} in glob: `{glob}`. hint: Characters can be escaped with a backslash"
+        "Invalid character `{invalid}` at position {pos}. hint: Characters can be escaped with a backslash"
     )]
-    InvalidCharacter {
+    InvalidCharacter { pos: usize, invalid: InvalidChar },
-        glob: String,
-        pos: usize,
-        invalid: InvalidChar,
-    },
 
-    #[error(
+    #[error("Path separators can't be escaped, invalid character at position {pos}")]
-        "Path separators can't be escaped, invalid character at position {pos} in glob: `{glob}`"
+    InvalidEscapee { pos: usize },
-    )]
-    InvalidEscapee { glob: String, pos: usize },
 
-    #[error("Invalid character `{invalid}` in range at position {pos} in glob: `{glob}`")]
+    #[error("Invalid character `{invalid}` in range at position {pos}")]
-    InvalidCharacterRange {
+    InvalidCharacterRange { pos: usize, invalid: InvalidChar },
-        glob: String,
-        pos: usize,
-        invalid: InvalidChar,
-    },
 
-    #[error("Too many stars at position {pos} in glob: `{glob}`")]
+    #[error("Too many stars at position {pos}")]
-    TooManyStars { glob: String, pos: usize },
+    TooManyStars { pos: usize },
 
-    #[error("Trailing backslash at position {pos} in glob: `{glob}`")]
+    #[error("Trailing backslash at position {pos}")]
-    TrailingEscape { glob: String, pos: usize },
+    TrailingEscape { pos: usize },
 }
 
 #[derive(Copy, Clone, Debug)]
@@ -303,57 +298,57 @@ mod tests {
 
         assert_snapshot!(
             parse_err(".."),
-            @"The parent directory operator (`..`) at position 1 is not allowed in glob: `..`"
+            @"The parent directory operator (`..`) at position 1 is not allowed"
         );
         assert_snapshot!(
             parse_err("licenses/.."),
-            @"The parent directory operator (`..`) at position 10 is not allowed in glob: `licenses/..`"
+            @"The parent directory operator (`..`) at position 10 is not allowed"
         );
         assert_snapshot!(
             parse_err("licenses/LICEN!E.txt"),
-            @"Invalid character `!` at position 15 in glob: `licenses/LICEN!E.txt`. hint: Characters can be escaped with a backslash"
+            @"Invalid character `!` at position 15. hint: Characters can be escaped with a backslash"
         );
         assert_snapshot!(
             parse_err("licenses/LICEN[!C]E.txt"),
-            @"Invalid character `!` in range at position 15 in glob: `licenses/LICEN[!C]E.txt`"
+            @"Invalid character `!` in range at position 15"
         );
         assert_snapshot!(
             parse_err("licenses/LICEN[C?]E.txt"),
-            @"Invalid character `?` in range at position 16 in glob: `licenses/LICEN[C?]E.txt`"
+            @"Invalid character `?` in range at position 16"
         );
         assert_snapshot!(
             parse_err("******"),
-            @"Too many stars at position 1 in glob: `******`"
+            @"Too many stars at position 1"
         );
         assert_snapshot!(
             parse_err("licenses/**license"),
-            @"Too many stars at position 10 in glob: `licenses/**license`"
+            @"Too many stars at position 10"
         );
         assert_snapshot!(
             parse_err("licenses/***/licenses.csv"),
-            @"Too many stars at position 10 in glob: `licenses/***/licenses.csv`"
+            @"Too many stars at position 10"
         );
         assert_snapshot!(
             parse_err(r"**/@test"),
-            @"Invalid character `@` at position 4 in glob: `**/@test`. hint: Characters can be escaped with a backslash"
+            @"Invalid character `@` at position 4. hint: Characters can be escaped with a backslash"
         );
         // Escapes are not allowed in strict PEP 639 mode
         assert_snapshot!(
             parse_err(r"public domain/Gulliver\\’s Travels.txt"),
-            @r"Invalid character ` ` at position 7 in glob: `public domain/Gulliver\\’s Travels.txt`. hint: Characters can be escaped with a backslash"
+            @r"Invalid character ` ` at position 7. hint: Characters can be escaped with a backslash"
         );
         assert_snapshot!(
             parse_err(r"**/@test"),
-            @"Invalid character `@` at position 4 in glob: `**/@test`. hint: Characters can be escaped with a backslash"
+            @"Invalid character `@` at position 4. hint: Characters can be escaped with a backslash"
         );
         // Escaping slashes is not allowed.
         assert_snapshot!(
             parse_err(r"licenses\\MIT.txt"),
-            @r"Path separators can't be escaped, invalid character at position 9 in glob: `licenses\\MIT.txt`"
+            @r"Path separators can't be escaped, invalid character at position 9"
         );
         assert_snapshot!(
             parse_err(r"licenses\/MIT.txt"),
-            @r"Path separators can't be escaped, invalid character at position 9 in glob: `licenses\/MIT.txt`"
+            @r"Path separators can't be escaped, invalid character at position 9"
         );
     }
 
@@ -388,8 +383,8 @@ mod tests {
     #[track_caller]
     fn assert_absolute_path(pattern: &str, relative_to: impl AsRef<SystemPath>, expected: &str) {
         let pattern = PortableGlobPattern::parse(pattern, true).unwrap();
-        let absolute = pattern.into_absolute(relative_to);
+        let pattern = pattern.into_absolute(relative_to);
-        assert_eq!(&*absolute, expected);
+        assert_eq!(pattern.absolute(), expected);
     }
 
     #[test]

crates/ty_project/src/metadata/settings.rs

@@ -1,9 +1,10 @@
 use std::sync::Arc;
 
-use ruff_db::diagnostic::DiagnosticFormat;
+use ruff_db::{diagnostic::DiagnosticFormat, files::File};
 use ty_python_semantic::lint::RuleSelection;
 
-use crate::glob::IncludeExcludeFilter;
+use crate::metadata::options::InnerOverrideOptions;
+use crate::{Db, combine::Combine, glob::IncludeExcludeFilter};
 
 /// The resolved [`super::Options`] for the project.
 ///
@@ -23,6 +24,13 @@ pub struct Settings {
     pub(super) rules: Arc<RuleSelection>,
     pub(super) terminal: TerminalSettings,
     pub(super) src: SrcSettings,
+
+    /// Settings for configuration overrides that apply to specific file patterns.
+    ///
+    /// Each override can specify include/exclude patterns and rule configurations
+    /// that apply to matching files. Multiple overrides can match the same file,
+    /// with later overrides taking precedence.
+    pub(super) overrides: Vec<Override>,
 }
 
 impl Settings {
@@ -41,6 +49,10 @@ impl Settings {
     pub fn terminal(&self) -> &TerminalSettings {
         &self.terminal
     }
+
+    pub fn overrides(&self) -> &[Override] {
+        &self.overrides
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
@@ -54,3 +66,138 @@ pub struct SrcSettings {
     pub respect_ignore_files: bool,
     pub files: IncludeExcludeFilter,
 }
+
+/// A single configuration override that applies to files matching specific patterns.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Override {
+    /// File pattern filter to determine which files this override applies to.
+    pub(super) files: IncludeExcludeFilter,
+
+    /// The raw options as specified in the configuration (minus `include` and `exclude`.
+    /// Necessary to merge multiple overrides if necessary.
+    pub(super) options: Arc<InnerOverrideOptions>,
+
+    /// Pre-resolved rule selection for this override alone.
+    /// Used for efficient lookup when only this override matches a file.
+    pub(super) settings: Arc<OverrideSettings>,
+}
+
+impl Override {
+    /// Returns whether this override applies to the given file path.
+    pub fn matches_file(&self, path: &ruff_db::system::SystemPath) -> bool {
+        use crate::glob::{GlobFilterCheckMode, IncludeResult};
+
+        matches!(
+            self.files
+                .is_file_included(path, GlobFilterCheckMode::Adhoc),
+            IncludeResult::Included
+        )
+    }
+}
+
+/// Resolves the settings for a given file.
+#[salsa::tracked(returns(ref))]
+pub(crate) fn file_settings(db: &dyn Db, file: File) -> FileSettings {
+    let settings = db.project().settings(db);
+
+    let path = match file.path(db) {
+        ruff_db::files::FilePath::System(path) => path,
+        ruff_db::files::FilePath::SystemVirtual(_) | ruff_db::files::FilePath::Vendored(_) => {
+            return FileSettings::Global;
+        }
+    };
+
+    let mut matching_overrides = settings
+        .overrides()
+        .iter()
+        .filter(|over| over.matches_file(path));
+
+    let Some(first) = matching_overrides.next() else {
+        // If the file matches no override, it uses the global settings.
+        return FileSettings::Global;
+    };
+
+    let Some(second) = matching_overrides.next() else {
+        tracing::debug!("Applying override for file `{path}`: {}", first.files);
+        // If the file matches only one override, return that override's settings.
+        return FileSettings::File(Arc::clone(&first.settings));
+    };
+
+    let mut filters = tracing::enabled!(tracing::Level::DEBUG)
+        .then(|| format!("({}), ({})", first.files, second.files));
+
+    let mut overrides = vec![Arc::clone(&first.options), Arc::clone(&second.options)];
+
+    for over in matching_overrides {
+        use std::fmt::Write;
+
+        if let Some(filters) = &mut filters {
+            let _ = write!(filters, ", ({})", over.files);
+        }
+
+        overrides.push(Arc::clone(&over.options));
+    }
+
+    if let Some(filters) = &filters {
+        tracing::debug!("Applying multiple overrides for file `{path}`: {filters}");
+    }
+
+    merge_overrides(db, overrides, ())
+}
+
+/// Merges multiple override options, caching the result.
+///
+/// Overrides often apply to multiple files. This query ensures that we avoid
+/// resolving the same override combinations multiple times.
+///
+/// ## What's up with the `()` argument?
+///
+/// This is to make Salsa happy because it requires that queries with only a single argument
+/// take a salsa-struct as argument, which isn't the case here. The `()` enables salsa's
+/// automatic interning for the arguments.
+#[salsa::tracked]
+fn merge_overrides(db: &dyn Db, overrides: Vec<Arc<InnerOverrideOptions>>, _: ()) -> FileSettings {
+    let mut overrides = overrides.into_iter().rev();
+    let mut merged = (*overrides.next().unwrap()).clone();
+
+    for option in overrides {
+        merged.combine_with((*option).clone());
+    }
+
+    merged
+        .rules
+        .combine_with(db.project().metadata(db).options().rules.clone());
+
+    let Some(rules) = merged.rules else {
+        return FileSettings::Global;
+    };
+
+    // It's okay to ignore the errors here because the rules are eagerly validated
+    // during `overrides.to_settings()`.
+    let rules = rules.to_rule_selection(db, &mut Vec::new());
+    FileSettings::File(Arc::new(OverrideSettings { rules }))
+}
+
+/// The resolved settings for a file.
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub enum FileSettings {
+    /// The file uses the global settings.
+    Global,
+
+    /// The file has specific override settings.
+    File(Arc<OverrideSettings>),
+}
+
+impl FileSettings {
+    pub fn rules<'a>(&'a self, db: &'a dyn Db) -> &'a RuleSelection {
+        match self {
+            FileSettings::Global => db.project().settings(db).rules(),
+            FileSettings::File(override_settings) => &override_settings.rules,
+        }
+    }
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct OverrideSettings {
+    pub(super) rules: RuleSelection,
+}

crates/ty_project/src/metadata/value.rs

@@ -407,6 +407,12 @@ impl RelativeIncludePattern {
     }
 }
 
+impl std::fmt::Display for RelativeIncludePattern {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
 #[derive(
     Debug,
     Clone,
@@ -456,3 +462,9 @@ impl RelativeExcludePattern {
         Ok(pattern.into_absolute(relative_to))
     }
 }
+
+impl std::fmt::Display for RelativeExcludePattern {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}

crates/ty_python_semantic/src/db.rs

@@ -7,7 +7,8 @@ use ruff_db::{Db as SourceDb, Upcast};
 pub trait Db: SourceDb + Upcast<dyn SourceDb> {
     fn is_file_open(&self, file: File) -> bool;
 
-    fn rule_selection(&self) -> &RuleSelection;
+    /// Resolves the rule selection for a given file.
+    fn rule_selection(&self, file: File) -> &RuleSelection;
 
     fn lint_registry(&self) -> &LintRegistry;
 }
@@ -126,7 +127,7 @@ pub(crate) mod tests {
             !file.path(self).is_vendored_path()
         }
 
-        fn rule_selection(&self) -> &RuleSelection {
+        fn rule_selection(&self, _file: File) -> &RuleSelection {
             &self.rule_selection
         }
 

crates/ty_python_semantic/src/lint.rs

@@ -32,7 +32,7 @@ pub struct LintMetadata {
     pub line: u32,
 }
 
-#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
 #[cfg_attr(
     feature = "serde",
     derive(serde::Serialize, serde::Deserialize),

crates/ty_python_semantic/src/python_platform.rs

@@ -1,10 +1,12 @@
 use std::fmt::{Display, Formatter};
 
+use ruff_macros::RustDoc;
+
 /// The target platform to assume when resolving types.
 #[derive(Debug, Clone, PartialEq, Eq)]
 #[cfg_attr(
     feature = "serde",
-    derive(serde::Serialize, serde::Deserialize),
+    derive(serde::Serialize, serde::Deserialize, RustDoc),
     serde(rename_all = "kebab-case")
 )]
 pub enum PythonPlatform {
@@ -57,6 +59,7 @@ impl Default for PythonPlatform {
 #[cfg(feature = "schemars")]
 mod schema {
     use crate::PythonPlatform;
+    use ruff_db::RustDoc;
     use schemars::_serde_json::Value;
     use schemars::JsonSchema;
     use schemars::r#gen::SchemaGenerator;
@@ -121,6 +124,10 @@ mod schema {
 
                     ..SubschemaValidation::default()
                 })),
+                metadata: Some(Box::new(Metadata {
+                    description: Some(<PythonPlatform as RustDoc>::rust_doc().to_string()),
+                    ..Metadata::default()
+                })),
 
                 ..SchemaObject::default()
             })

crates/ty_python_semantic/src/suppression.rs

@@ -290,7 +290,10 @@ impl<'a> CheckSuppressionsContext<'a> {
     }
 
     fn is_lint_disabled(&self, lint: &'static LintMetadata) -> bool {
-        !self.db.rule_selection().is_enabled(LintId::of(lint))
+        !self
+            .db
+            .rule_selection(self.file)
+            .is_enabled(LintId::of(lint))
     }
 
     fn report_lint(
@@ -315,7 +318,7 @@ impl<'a> CheckSuppressionsContext<'a> {
         range: TextRange,
         message: fmt::Arguments,
     ) {
-        let Some(severity) = self.db.rule_selection().severity(LintId::of(lint)) else {
+        let Some(severity) = self.db.rule_selection(self.file).severity(LintId::of(lint)) else {
             return;
         };
 

crates/ty_python_semantic/src/types/context.rs

@@ -401,7 +401,7 @@ impl<'db, 'ctx> LintDiagnosticGuardBuilder<'db, 'ctx> {
         let lint_id = LintId::of(lint);
         // Skip over diagnostics if the rule
         // is disabled.
-        let (severity, source) = ctx.db.rule_selection().get(lint_id)?;
+        let (severity, source) = ctx.db.rule_selection(ctx.file).get(lint_id)?;
         // If we're not in type checking mode,
         // we can bail now.
         if ctx.is_in_no_type_check() {

crates/ty_python_semantic/tests/corpus.rs

@@ -260,7 +260,7 @@ impl ty_python_semantic::Db for CorpusDb {
         !file.path(self).is_vendored_path()
     }
 
-    fn rule_selection(&self) -> &RuleSelection {
+    fn rule_selection(&self, _file: File) -> &RuleSelection {
         &self.rule_selection
     }
 

crates/ty_test/src/db.rs

@@ -90,7 +90,7 @@ impl SemanticDb for Db {
         !file.path(self).is_vendored_path()
     }
 
-    fn rule_selection(&self) -> &RuleSelection {
+    fn rule_selection(&self, _file: File) -> &RuleSelection {
         &self.rule_selection
     }
 

fuzz/fuzz_targets/ty_check_invalid_syntax.rs

@@ -18,8 +18,8 @@ use ruff_python_parser::{Mode, ParseOptions, parse_unchecked};
 use ty_python_semantic::lint::LintRegistry;
 use ty_python_semantic::types::check_types;
 use ty_python_semantic::{
-    Db as SemanticDb, Program, ProgramSettings, PythonPlatform, SearchPathSettings,
+    Db as SemanticDb, Program, ProgramSettings, PythonPlatform, PythonVersionWithSource,
-    default_lint_registry, lint::RuleSelection, PythonVersionWithSource,
+    SearchPathSettings, default_lint_registry, lint::RuleSelection,
 };
 
 /// Database that can be used for testing.
@@ -95,7 +95,7 @@ impl SemanticDb for TestDb {
         !file.path(self).is_vendored_path()
     }
 
-    fn rule_selection(&self) -> &RuleSelection {
+    fn rule_selection(&self, _file: File) -> &RuleSelection {
         &self.rule_selection
     }
 

ty.schema.json

@@ -14,6 +14,16 @@
         }
       ]
     },
+    "overrides": {
+      "description": "Override configurations for specific file patterns.\n\nEach override specifies include/exclude patterns and rule configurations that apply to matching files. Multiple overrides can match the same file, with later overrides taking precedence.",
+      "type": [
+        "array",
+        "null"
+      ],
+      "items": {
+        "$ref": "#/definitions/OverrideOptions"
+      }
+    },
     "rules": {
       "description": "Configures the enabled rules and their severity.\n\nSee [the rules documentation](https://ty.dev/rules) for a list of all available rules.\n\nValid severities are:\n\n* `ignore`: Disable the rule. * `warn`: Enable the rule and create a warning diagnostic. * `error`: Enable the rule and create an error diagnostic. ty will exit with a non-zero code if any error diagnostics are emitted.",
       "anyOf": [
@@ -147,7 +157,45 @@
         }
       ]
     },
+    "OverrideOptions": {
+      "type": "object",
+      "properties": {
+        "exclude": {
+          "description": "A list of file and directory patterns to exclude from this override.\n\nPatterns follow a syntax similar to `.gitignore`. Exclude patterns take precedence over include patterns within the same override.\n\nIf not specified, defaults to `[]` (excludes no files).",
+          "type": [
+            "array",
+            "null"
+          ],
+          "items": {
+            "type": "string"
+          }
+        },
+        "include": {
+          "description": "A list of file and directory patterns to include for this override.\n\nThe `include` option follows a similar syntax to `.gitignore` but reversed: Including a file or directory will make it so that it (and its contents) are affected by this override.\n\nIf not specified, defaults to `[\"**\"]` (matches all files).",
+          "type": [
+            "array",
+            "null"
+          ],
+          "items": {
+            "type": "string"
+          }
+        },
+        "rules": {
+          "description": "Rule overrides for files matching the include/exclude patterns.\n\nThese rules will be merged with the global rules, with override rules taking precedence for matching files. You can set rules to different severity levels or disable them entirely.",
+          "anyOf": [
+            {
+              "$ref": "#/definitions/Rules"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        }
+      },
+      "additionalProperties": false
+    },
     "PythonPlatform": {
+      "description": "The target platform to assume when resolving types.\n",
       "anyOf": [
         {
           "type": "string"
@@ -882,7 +930,7 @@
           }
         },
         "include": {
-          "description": "A list of files and directories to check. The `include` option follows a similar syntax to `.gitignore` but reversed: Including a file or directory will make it so that it (and its contents) are type checked.\n\n- `./src/` matches only a directory - `./src` matches both files and directories - `src` matches files or directories named `src` anywhere in the tree (e.g. `./src` or `./tests/src`) - `*` matches any (possibly empty) sequence of characters (except `/`). - `**` matches zero or more path components. This sequence **must** form a single path component, so both `**a` and `b**` are invalid and will result in an error. A sequence of more than two consecutive `*` characters is also invalid. - `?` matches any single character except `/` - `[abc]` matches any character inside the brackets. Character sequences can also specify ranges of characters, as ordered by Unicode, so e.g. `[0-9]` specifies any character between `0` and `9` inclusive. An unclosed bracket is invalid.\n\nUnlike `exclude`, all paths are anchored relative to the project root (`src` only matches `<project_root>/src` and not `<project_root>/test/src`).\n\n`exclude` take precedence over `include`.",
+          "description": "A list of files and directories to check. The `include` option follows a similar syntax to `.gitignore` but reversed: Including a file or directory will make it so that it (and its contents) are type checked.\n\n- `./src/` matches only a directory - `./src` matches both files and directories - `src` matches a file or directory named `src` - `*` matches any (possibly empty) sequence of characters (except `/`). - `**` matches zero or more path components. This sequence **must** form a single path component, so both `**a` and `b**` are invalid and will result in an error. A sequence of more than two consecutive `*` characters is also invalid. - `?` matches any single character except `/` - `[abc]` matches any character inside the brackets. Character sequences can also specify ranges of characters, as ordered by Unicode, so e.g. `[0-9]` specifies any character between `0` and `9` inclusive. An unclosed bracket is invalid.\n\nUnlike `exclude`, all paths are anchored relative to the project root (`src` only matches `<project_root>/src` and not `<project_root>/test/src`).\n\n`exclude` takes precedence over `include`.",
           "type": [
             "array",
             "null"