Module locator 

Locator: the one grammar for referring to content across events and sessions. The part crates/kernel/spec/Locator.lean specifies this module. Two schemes only:

cas:b3-<hex64>[#(L|B)<a>-<b>] | file:<address>@<hex40>[#(L|B)<a>-<b>]

Invariants owned here:

• fail-closed: whatever is not exactly the grammar is E_LOCATOR_INVALID; unknown schemes and unknown algorithm tags are errors, never fallbacks.
• canonical echo: parse additionally requires Display(parsed) == raw, which closes every non-canonical spelling (uppercase hex, leading zeros, + signs) with one rule.
• secret: never parses here: SecretRef has a separate parser by design, so a read path can never redeem a credential.
• range semantics: L is 1-based closed (editor precedent), B is 0-based closed (HTTP Range precedent); from <= to always.

B3Hash lives here because b3- is part of this grammar; the event chain and CAS reuse the same type (one hash function library-wide).

Structs

B3Hash

BLAKE3 digest, 32 bytes; displayed as 64 lowercase hex digits.

GitOid

Git object id, 40 lowercase hex digits (SHA-1 repositories; other lengths are rejected; SHA-256 repositories are not accepted).

Enums

Locator

The two-scheme reference grammar.

Range

Sub-content range. Lines is 1-based closed; Bytes is 0-based closed.