Struct FallowConfig 

pub struct FallowConfig {

    pub schema: Option<String>,
    pub extends: Vec<String>,
    pub entry: Vec<String>,
    pub ignore_patterns: Vec<String>,
    pub framework: Vec<ExternalPluginDef>,
    pub workspaces: Option<WorkspaceConfig>,
    pub ignore_dependencies: Vec<String>,
    pub ignore_exports: Vec<IgnoreExportRule>,
    pub duplicates: DuplicatesConfig,
    pub health: HealthConfig,
    pub rules: RulesConfig,
    pub boundaries: BoundaryConfig,
    pub production: bool,
    pub plugins: Vec<String>,
    pub dynamically_loaded: Vec<String>,
    pub overrides: Vec<ConfigOverride>,
    pub codeowners: Option<String>,
    pub public_packages: Vec<String>,
    pub regression: Option<RegressionConfig>,
}

User-facing configuration loaded from .fallowrc.json or fallow.toml.

Examples

use fallow_config::FallowConfig;

// Default config has sensible defaults
let config = FallowConfig::default();
assert!(config.entry.is_empty());
assert!(!config.production);

// Deserialize from JSON
let config: FallowConfig = serde_json::from_str(r#"{
    "entry": ["src/main.ts"],
    "production": true
}"#).unwrap();
assert_eq!(config.entry, vec!["src/main.ts"]);
assert!(config.production);

Fields

schema: Option<String>

JSON Schema reference (ignored during deserialization).

extends: Vec<String>

Base config files to extend from.

Supports three resolution strategies:

• Relative paths: "./base.json" — resolved relative to the config file.
• npm packages: "npm:@co/config" — resolved by walking up node_modules/. Package resolution checks package.json exports/main first, then falls back to standard config file names. Subpaths are supported (e.g., npm:@co/config/strict.json).
• HTTPS URLs: "https://example.com/fallow-base.json" — fetched remotely. Only HTTPS is supported (no plain HTTP). URL-sourced configs may extend other URLs or npm: packages, but not relative paths. Only JSON/JSONC format is supported for remote configs. Timeout is configurable via FALLOW_EXTENDS_TIMEOUT_SECS (default: 5s).

Base configs are loaded first, then this config’s values override them. Later entries in the array override earlier ones.

Note: npm: resolution uses node_modules/ directory walk-up and is incompatible with Yarn Plug’n’Play (PnP), which has no node_modules/. URL extends fetch on every run (no caching). For reliable CI, prefer npm: for private or critical configs.

entry: Vec<String>

Additional entry point glob patterns.

ignore_patterns: Vec<String>

Glob patterns to ignore from analysis.

framework: Vec<ExternalPluginDef>

Custom framework definitions (inline plugin definitions).

workspaces: Option<WorkspaceConfig>

Workspace overrides.

ignore_dependencies: Vec<String>

Dependencies to ignore (always considered used and always considered available).

Listed dependencies are excluded from both unused dependency and unlisted dependency detection. Useful for runtime-provided packages like bun:sqlite or implicitly available dependencies.

ignore_exports: Vec<IgnoreExportRule>

Export ignore rules.

duplicates: DuplicatesConfig

Duplication detection settings.

health: HealthConfig

Complexity health metrics settings.

rules: RulesConfig

Per-issue-type severity rules.

boundaries: BoundaryConfig

Architecture boundary enforcement configuration.

production: bool

Production mode: exclude test/dev files, only start/build scripts.

plugins: Vec<String>

Paths to external plugin files or directories containing plugin files.

Supports TOML, JSON, and JSONC formats.

In addition to these explicit paths, fallow automatically discovers:

• *.toml, *.json, *.jsonc files in .fallow/plugins/
• fallow-plugin-*.{toml,json,jsonc} files in the project root

dynamically_loaded: Vec<String>

Glob patterns for files that are dynamically loaded at runtime (plugin directories, locale files, etc.). These files are treated as always-used and will never be flagged as unused.

overrides: Vec<ConfigOverride>

Per-file rule overrides matching oxlint’s overrides pattern.

codeowners: Option<String>

Path to a CODEOWNERS file for --group-by owner.

When unset, fallow auto-probes CODEOWNERS, .github/CODEOWNERS, .gitlab/CODEOWNERS, and docs/CODEOWNERS. Set this to use a non-standard location.

public_packages: Vec<String>

Workspace package name patterns that are public libraries. Exports from these packages are not flagged as unused.

regression: Option<RegressionConfig>

Regression detection baseline embedded in config. Stores issue counts from a known-good state for CI regression checks. Populated by --save-regression-baseline (no path), read by --fail-on-regression.

Implementations

impl FallowConfig

pub fn load(path: &Path) -> Result<Self, Report>

Load config from a fallow config file (TOML or JSON/JSONC).

The format is detected from the file extension:

• .toml → TOML
• .json → JSON (with JSONC comment stripping)

Supports extends for config inheritance. Extended configs are loaded and deep-merged before this config’s values are applied.

Errors

Returns an error when the config file cannot be read, merged, or deserialized.

pub fn find_config_path(start: &Path) -> Option<PathBuf>

Find the config file path without loading it. Searches the same locations as find_and_load.

pub fn find_and_load(start: &Path) -> Result<Option<(Self, PathBuf)>, String>

Find and load config, searching from start up to the project root.

Errors

Returns an error if a config file is found but cannot be read or parsed.

pub fn json_schema() -> Value

Generate JSON Schema for the configuration format.

impl FallowConfig

pub fn resolve( self, root: PathBuf, output: OutputFormat, threads: usize, no_cache: bool, quiet: bool, ) -> ResolvedConfig

Resolve into a fully resolved config with compiled globs.

Trait Implementations

impl Debug for FallowConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for FallowConfig

fn default() -> FallowConfig

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for FallowConfig

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl JsonSchema for FallowConfig

fn schema_name() -> Cow<'static, str>

The name of the generated JSON Schema.

fn schema_id() -> Cow<'static, str>

Returns a string that uniquely identifies the schema produced by this type.

fn json_schema(generator: &mut SchemaGenerator) -> Schema

Generates a JSON Schema for this type.

fn inline_schema() -> bool

Whether JSON Schemas generated for this type should be included directly in parent schemas, rather than being re-used where possible using the $ref keyword.

impl Serialize for FallowConfig

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.