Enum SlugError 

pub enum SlugError {
    IdTooLong {
        input: String,
        length: usize,
        max: usize,
    },
    TitleEmpty {
        input: String,
    },
    TitleHasInvalidChars {
        input: String,
        invalid_chars: Vec<char>,
        proposed_slug: String,
    },
    TitleHasControlChars {
        input: String,
        control_chars: Vec<char>,
        proposed_slug: String,
    },
}

Error cases for title→slug derivation. title_to_slug itself is total — any title produces a slug (residual cases like all-emoji collapse to a deterministic short-hash id) — so it never returns these variants directly. The strict mutation-entry gate validate_and_derive_slug returns them when the input would have fallen back to the hash slug or would have had characters dropped; enforce_id_length returns Self::IdTooLong when the derived mem--slug exceeds the read-path length cap.

Loader and parse paths continue to call title_to_slug so pre-gate entities created with the old permissive pipeline remain readable.

Variants

IdTooLong

The derived mem--slug id exceeds ENTITY_ID_MAX_LEN. The read-path validator rejects ids past this length, so without this guard a title that the write path accepts produces an entity that is silently unreachable on read.

The bound is on the composed id (<mem>--<slug>), which is also the on-disk filename — so the budget is mem-name-dependent and the same title can be valid in a short-named mem and rejected in a longer-named one. input echoes that composed id (not the title) so it agrees with length: the payload measures one quantity, the id, end to end. max is ENTITY_ID_MAX_LEN so the agent can shorten by the exact delta. F2 + F4.

Fields

input: String

The composed <mem>--<slug> id whose length exceeded the cap. Echoed as the input wire field so input and length describe the same measured quantity.

length: usize

max: usize

TitleEmpty

Strict mutation-entry rejection: the title is empty, whitespace-only, or composed exclusively of pipeline-separator characters (hyphens) so the slug pipeline would have collapsed it to a hash-fallback id. Recovery: supply a non-empty title with at least one alphanumeric character. F4.

Fields

input: String

TitleHasInvalidChars

Strict mutation-entry rejection: one or more characters in the title would have been dropped by the slug pipeline (anything that isn’t Unicode alphanumeric, whitespace, or hyphen after NFC + case-fold). invalid_chars lists each distinct offending character in source order; proposed_slug is the slug the permissive pipeline would have produced, suitable for a mechanical retry against a sanitised title. F10 + F19.

Fields

input: String

invalid_chars: Vec<char>

proposed_slug: String

TitleHasControlChars

Strict mutation-entry rejection: the title contains control characters (newline, tab, other C0/C1 controls). These are Unicode whitespace, so the slug pipeline silently folds them to hyphens and accepts the title — but they survive verbatim into the stored # H1 heading, which then splits across lines so every read truncates the title at the first control char (search and memstead_entity see only the prefix). Refused up front with the same named-offenders + proposed_slug recovery shape the invalid-char guard uses. control_chars lists each distinct offender in source order; proposed_slug is the slug the pipeline would produce, for a mechanical retry with a single-line title. F8.

Fields

input: String

control_chars: Vec<char>

proposed_slug: String

Implementations

impl SlugError

pub fn reason(&self) -> &'static str

Stable discriminator for the structured-details reason field on the INVALID_TITLE wire envelope. Each surface (MCP, CLI) reads this when building the response payload.

Trait Implementations

impl Debug for SlugError

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

Formats the value using the given formatter.

impl Display for SlugError

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

Formats the value using the given formatter.

impl Error for SlugError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.