Ask your agent: “Add agent-first-slug to my project and use it to slugify titles for URL path segments.”

Start by choosing the target surface: a local filesystem path segment, a URL path segment, or a legacy slug format you need to preserve. The examples below show complete config values so the behavior is visible at the call site.

Install

cargo add agent-first-slug

Default Unicode Slugs

use agent_first_slug::{slugify, SlugConfig};

let config = SlugConfig::default();

assert_eq!(slugify("Hello", &config)?.slug, "hello");
assert_eq!(slugify("Hello World", &config)?.slug, "hello-world");
assert_eq!(slugify("Hello,  world!!!", &config)?.slug, "hello-world");
assert_eq!(slugify("-- already -- spaced --", &config)?.slug, "already-spaced");
assert_eq!(slugify("!!!", &config)?.slug, "");
# Ok::<(), agent_first_slug::SlugError>(())

Unicode letters and numbers are preserved by default:

use agent_first_slug::{slugify, SlugConfig};

let config = SlugConfig::default();

assert_eq!(
    slugify("現在的Nobody，未來的Somebody！", &config)?.slug,
    "現在的nobody-未來的somebody"
);
assert_eq!(
    slugify("牙好，胃口就好，身体倍儿棒，吃嘛嘛香。", &config)?.slug,
    "牙好-胃口就好-身体倍儿棒-吃嘛嘛香"
);
assert_eq!(slugify("お元気ですか？", &config)?.slug, "お元気ですか");
# Ok::<(), agent_first_slug::SlugError>(())

Local Filesystem Path Segment

Use this when the slug will be one segment in a local path. Slugify each segment separately; do not pass a full path through one slug call.

Requirements for this target:

Reject empty output unless the caller provides a fallback.
Reject /, \\, Unicode whitespace, and control characters.
Reject . and .. to avoid current-directory and parent-directory meanings.
Prefer replacing dots unless the caller explicitly wants dots in filenames.
Choose ASCII-only if the path must be portable across legacy filesystems or tools.

use agent_first_slug::{
    slugify, AllowedCharacterSet, DotHandlingPolicy, EmptyOutputPolicy, SlugConfig,
    SlugValidationPolicy, TransliterationPolicy,
};

let config = SlugConfig {
    replacement_delimiter: '-',
    lowercase_enabled: true,
    max_slug_chars: None,
    allowed_character_set: AllowedCharacterSet::UnicodeAlphanumericCharacters,
    dot_handling_policy: DotHandlingPolicy::ReplaceAllDots,
    transliteration_policy: TransliterationPolicy::None,
    validation_policy: SlugValidationPolicy::LocalPathSegment,
    empty_output_policy: EmptyOutputPolicy::UseFallbackSlug("fallback".to_string()),
};

assert_eq!(slugify("Ubuntu 16.04", &config)?.slug, "ubuntu-16-04");
assert_eq!(slugify("你好，世界", &config)?.slug, "你好-世界");
assert_eq!(slugify("!!!", &config)?.slug, "fallback");
# Ok::<(), agent_first_slug::SlugError>(())

ASCII-only path segment with fallback:

use agent_first_slug::{
    slugify, AllowedCharacterSet, DotHandlingPolicy, EmptyOutputPolicy, SlugConfig,
    SlugValidationPolicy, TransliterationPolicy,
};

let config = SlugConfig {
    replacement_delimiter: '-',
    lowercase_enabled: true,
    max_slug_chars: None,
    allowed_character_set: AllowedCharacterSet::AsciiAlphanumericCharacters,
    dot_handling_policy: DotHandlingPolicy::ReplaceAllDots,
    transliteration_policy: TransliterationPolicy::None,
    validation_policy: SlugValidationPolicy::LocalPathSegment,
    empty_output_policy: EmptyOutputPolicy::UseFallbackSlug("fallback".to_string()),
};

assert_eq!(slugify("Hello 世界", &config)?.slug, "hello");
assert_eq!(slugify("Ubuntu 16.04", &config)?.slug, "ubuntu-16-04");
assert_eq!(slugify("你好，世界", &config)?.slug, "fallback");
# Ok::<(), agent_first_slug::SlugError>(())

URL Path Segment

Use this when the slug will be one segment in a URL path. The returned slug is raw UTF-8; percent-encode it or use a URL library’s path-segment API when building the final URL.

Requirements for this target:

Reject empty output unless the caller provides a fallback.
Reject /, ?, #, raw %, Unicode whitespace, controls, and \\.
Reject . and .. for route safety.
Preserve dots between decimal digits if version numbers matter.
Do not manually concatenate unescaped slugs into URLs.

use agent_first_slug::{
    slugify, AllowedCharacterSet, DotHandlingPolicy, EmptyOutputPolicy, SlugConfig,
    SlugValidationPolicy, TransliterationPolicy,
};

let config = SlugConfig {
    replacement_delimiter: '-',
    lowercase_enabled: true,
    max_slug_chars: None,
    allowed_character_set: AllowedCharacterSet::UnicodeLettersAndDecimalDigits,
    dot_handling_policy: DotHandlingPolicy::PreserveDotsBetweenDecimalDigits,
    transliteration_policy: TransliterationPolicy::None,
    validation_policy: SlugValidationPolicy::UrlPathSegment,
    empty_output_policy: EmptyOutputPolicy::KeepEmptySlug,
};

assert_eq!(slugify("Ubuntu 16.04", &config)?.slug, "ubuntu-16.04");
assert_eq!(slugify("T.U.S.F.G.E.3.0.8", &config)?.slug, "t-u-s-f-g-e-3.0.8");
assert_eq!(slugify(".18 increased ! ", &config)?.slug, "18-increased");
assert_eq!(slugify("お元気ですか？", &config)?.slug, "お元気ですか");
# Ok::<(), agent_first_slug::SlugError>(())

Dot Handling

use agent_first_slug::{slugify, DotHandlingPolicy, SlugConfig};

let replace_all_dots = SlugConfig {
    dot_handling_policy: DotHandlingPolicy::ReplaceAllDots,
    ..SlugConfig::default()
};
let preserve_all_dots = SlugConfig {
    dot_handling_policy: DotHandlingPolicy::PreserveAllDots,
    ..SlugConfig::default()
};
let preserve_version_dots = SlugConfig {
    dot_handling_policy: DotHandlingPolicy::PreserveDotsBetweenDecimalDigits,
    ..SlugConfig::default()
};

assert_eq!(slugify("Ubuntu 16.04", &replace_all_dots)?.slug, "ubuntu-16-04");
assert_eq!(slugify("A.B..C", &preserve_all_dots)?.slug, "a.b..c");
assert_eq!(slugify("T.U.S.F.G.E.3.0.8", &preserve_version_dots)?.slug, "t-u-s-f-g-e-3.0.8");
# Ok::<(), agent_first_slug::SlugError>(())

Transliteration

Transliteration is caller-provided, so legacy behavior can be expressed without a named preset in the library.

use agent_first_slug::{
    slugify, AllowedCharacterSet, SlugConfig, TransliterationPolicy,
};

static MAP: &[(&str, &str)] = &[("Æ", "AE"), ("東京", "Tokyo")];
let config = SlugConfig {
    allowed_character_set: AllowedCharacterSet::AsciiAlphanumericCharacters,
    transliteration_policy: TransliterationPolicy::StaticReplacementMap(MAP),
    ..SlugConfig::default()
};

assert_eq!(slugify("Æther 東京", &config)?.slug, "aether-tokyo");
# Ok::<(), agent_first_slug::SlugError>(())

Truncation And Empty Output

max_slug_chars counts Unicode scalar values and runs after lowercasing; any trailing delimiter the cut exposes is then stripped. Empty handling runs after truncation, and a fallback is inserted verbatim — it is validated but is not lowercased or truncated.

use agent_first_slug::{slugify, EmptyOutputPolicy, SlugConfig};

let truncated = SlugConfig {
    max_slug_chars: Some(8),
    ..SlugConfig::default()
};
let fallback_after_truncation = SlugConfig {
    max_slug_chars: Some(0),
    empty_output_policy: EmptyOutputPolicy::UseFallbackSlug("fallback".to_string()),
    ..SlugConfig::default()
};

assert_eq!(slugify("Long Example", &truncated)?.slug, "long-exa");
assert_eq!(slugify("Long Example", &fallback_after_truncation)?.slug, "fallback");
# Ok::<(), agent_first_slug::SlugError>(())

Validation Only

use agent_first_slug::{validate_slug, SlugError, SlugValidationPolicy};

assert_eq!(validate_slug("safe-name", SlugValidationPolicy::LocalPathSegment), Ok(()));
assert_eq!(
    validate_slug("a/b", SlugValidationPolicy::LocalPathSegment),
    Err(SlugError::PathSegmentSeparator { character: '/' })
);
assert_eq!(
    validate_slug("a?b", SlugValidationPolicy::UrlPathSegment),
    Err(SlugError::UrlPathSegmentReservedCharacter { character: '?' })
);

Agent-First Slug