diff --git a/.github/workflows/deed-conformance.yml b/.github/workflows/deed-conformance.yml
index 7744b8b65..3385905dd 100644
--- a/.github/workflows/deed-conformance.yml
+++ b/.github/workflows/deed-conformance.yml
@@ -26,6 +26,8 @@ on:
       - '.github/workflows/deed-conformance.yml'
       - 'scripts/uuid-v8.js'
       - 'scripts/tests/bun/**'
+      - 'tools/uuid-v8/**'
+      - 'scripts/tests/rust/**'
   pull_request:
     paths:
       - '**.deed'
@@ -33,6 +35,8 @@ on:
       - '.github/workflows/deed-conformance.yml'
       - 'scripts/uuid-v8.js'
       - 'scripts/tests/bun/**'
+      - 'tools/uuid-v8/**'
+      - 'scripts/tests/rust/**'
   workflow_call:
     inputs:
       require-files:
@@ -80,6 +84,11 @@ jobs:
       - name: uuid-v8 generator against an independent sha256sum oracle (#u8 = profile C)
         if: github.repository == 'hyperpolymath/standards'
         run: bash scripts/tests/bun/uuid-v8-gen-test.sh
+      - name: uuid-v8 Rust generator (tools/uuid-v8) against the same oracle, the bun generator and check-uuid-v8.sh
+        if: github.repository == 'hyperpolymath/standards'
+        run: |
+          cargo test --quiet --locked --manifest-path tools/uuid-v8/Cargo.toml
+          bash scripts/tests/rust/uuid-v8-rs-test.sh
       - name: lint every committed deed
         env:
           REQUIRE_FILES: ${{ inputs.require-files || false }}
diff --git a/scripts/tests/rust/uuid-v8-rs-test.sh b/scripts/tests/rust/uuid-v8-rs-test.sh
new file mode 100755
index 000000000..bdb1d67ed
--- /dev/null
+++ b/scripts/tests/rust/uuid-v8-rs-test.sh
@@ -0,0 +1,83 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: MPL-2.0
+#
+# Proves tools/uuid-v8 (the shared Rust ESTATE-UUID-V8 generator, ADR-008)
+# emits the same ids as the independent oracle in
+# scripts/tests/bun/uuid-v8-gen-test.sh (sha256sum and shell nibble
+# arithmetic), the same ids as scripts/uuid-v8.js when bun is present, and ids
+# that check-uuid-v8.sh --strict accepts.
+#
+# Lives below scripts/tests/ so run-shell-test-suite.sh (maxdepth 1) does not
+# discover it; deed-conformance.yml runs it next to the bun generator test.
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/../../.." && pwd)"
+MANIFEST="$ROOT/tools/uuid-v8/Cargo.toml"
+CHECK="$ROOT/scripts/check-uuid-v8.sh"
+WORK="$(mktemp -d)"; trap 'rm -rf "$WORK"' EXIT
+pass=0; fail=0
+
+cargo build --quiet --release --locked --manifest-path "$MANIFEST"
+GEN="$ROOT/tools/uuid-v8/target/release/uuid-v8"
+
+# Record one assertion: check <label> <command...>; runs the command errexit-safe.
+check() {
+  local label=$1; shift
+  if "$@"; then pass=$((pass+1)); echo "  ok    $label"; else fail=$((fail+1)); echo "  FAIL  $label"; fi
+}
+
+# Independent profile C: first 16 bytes of SHA-256(domain:name), version and variant set by hand.
+oracle_c() {
+  local h v
+  h=$(printf '%s:%s' "$1" "$2" | sha256sum | cut -c1-32)
+  v=$(( (0x${h:16:1} & 0x3) | 0x8 ))
+  h="${h:0:12}8${h:13:3}$(printf '%x' "$v")${h:17:15}"
+  printf '%s-%s-%s-%s-%s\n' "${h:0:8}" "${h:8:4}" "${h:12:4}" "${h:16:4}" "${h:20:12}"
+}
+
+CASES='gv-clade-index|github.com/hyperpolymath/standards
+berrywiki-import|Main Page
+d|
+d|a:b c
+echidna-goal|é✓'
+
+echo "profile C matches the independent oracle"
+while IFS='|' read -r d n; do
+  want=$(oracle_c "$d" "$n"); got=$("$GEN" c "$d" "$n")
+  check "c $d:$n -> $want" [ "$got" = "$want" ]
+done <<<"$CASES"
+got=$("$GEN" deed "gv-clade-index:github.com/hyperpolymath/standards")
+check "deed body splits on the FIRST colon" [ "$got" = "$(oracle_c gv-clade-index github.com/hyperpolymath/standards)" ]
+
+if command -v bun >/dev/null 2>&1; then
+  echo "profile C agrees with scripts/uuid-v8.js"
+  while IFS='|' read -r d n; do
+    check "rust = bun for $d:$n" [ "$("$GEN" c "$d" "$n")" = "$(bun "$ROOT/scripts/uuid-v8.js" c "$d" "$n")" ]
+  done <<<"$CASES"
+else
+  echo "  skip  bun not installed: rust/bun agreement not checked"
+fi
+
+echo "profile C rejects bad domains"
+for d in "" "a:b" "a b"; do
+  rc=0; "$GEN" c "$d" x >/dev/null 2>&1 || rc=$?
+  check "domain '$d' is rejected" [ "$rc" -eq 1 ]
+done
+rc=0; "$GEN" bogus >/dev/null 2>&1 || rc=$?
+check "bad usage exits 2" [ "$rc" -eq 2 ]
+
+echo "profile T"
+before=$(( $(date +%s%3N) - 1000 ))
+t=$("$GEN" t)
+after=$(( $(date +%s%3N) + 1000 ))
+check "version nibble is 8 ($t)" [ "${t:14:1}" = 8 ]
+check "variant is 10" grep -qE '^[89ab]$' <<<"${t:19:1}"
+ms=$(( 0x${t:0:8}${t:9:4} ))
+check "timestamp is now (unix ms)" test "$ms" -ge "$before" -a "$ms" -le "$after"
+check "two calls differ" [ "$t" != "$("$GEN" t)" ]
+
+echo "the strict checker accepts every generated id"
+{ "$GEN" t; "$GEN" c gv-clade-index github.com/o/n; } > "$WORK/ids.txt"
+check "check-uuid-v8.sh --strict passes" "$CHECK" --strict "$WORK"
+
+echo "PASS=$pass FAIL=$fail"
+[ "$fail" -eq 0 ]
diff --git a/tools/uuid-v8/Cargo.lock b/tools/uuid-v8/Cargo.lock
new file mode 100644
index 000000000..aea842cc5
--- /dev/null
+++ b/tools/uuid-v8/Cargo.lock
@@ -0,0 +1,267 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "block-buffer"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
+dependencies = [
+ "generic-array",
+]
+
+[[package]]
+name = "bumpalo"
+version = "3.20.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72f5acc6cb2ba439de613abc23857ec3d78374d8ed5ac84e9d11336e87da8649"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e7648175b45a9a48536d676f68d918270699102aa8dab5496df06904c914600"
+
+[[package]]
+name = "cpufeatures"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59ed5838eebb26a2bb2e58f6d5b5316989ae9d08bab10e0e6d103e656d1b0280"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "crypto-common"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78c8292055d1c1df0cce5d180393dc8cce0abec0a7102adb6c7b1eef6016d60a"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
+[[package]]
+name = "digest"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
+[[package]]
+name = "estate-uuid-v8"
+version = "0.1.0"
+dependencies = [
+ "sha2",
+ "uuid",
+]
+
+[[package]]
+name = "futures-core"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92d699e522242e69e3003b94ecc1f960f3a5e015aa7c5d7486e65ad01dd94f5e"
+
+[[package]]
+name = "futures-task"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cd417de3d1d015fc3bfd2b1ea46dfc7bab72ef86f1cc7cc9c78e728b34a6d1fd"
+
+[[package]]
+name = "futures-util"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d50a92467f8ba5dd6e3ee5d4bd04d73ab2e4e1c44474a0674821dfce14b79bc"
+dependencies = [
+ "futures-core",
+ "futures-task",
+ "pin-project-lite",
+ "slab",
+]
+
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
+[[package]]
+name = "getrandom"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "300e883d756b2e4ec94e02791f39b04b522276138852cfc41d9fb7e904106099"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "r-efi",
+]
+
+[[package]]
+name = "js-sys"
+version = "0.3.106"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7883d941dae510fb2d978fc3fe018c71c9e2892fd38854de3e8b92c2e5ad9cc5"
+dependencies = [
+ "cfg-if",
+ "futures-util",
+ "wasm-bindgen",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.190"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce5d3ddc6d3fa000eb1536d85e147bfe31aacaba692ed6a876f95cb7c855be78"
+
+[[package]]
+name = "once_cell"
+version = "1.21.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
+
+[[package]]
+name = "pin-project-lite"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.107"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "985e7ec9bb745e6ce6535b544d84d6cd6f7ad8bd711c398938ae983b91a766d9"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.47"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fbf4db142a473a8d80c26bbf18454ed458bf8d26c8219c331daecfdbd079001"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "r-efi"
+version = "6.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8dcc9c7d52a811697d2151c701e0d08956f92b0e24136cf4cf27b57a6a0d9bf"
+
+[[package]]
+name = "rustversion"
+version = "1.0.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf54715a573b99ac80df0bc206da022bcd442c974952c7b9720069370852e21f"
+
+[[package]]
+name = "sha2"
+version = "0.10.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7507d819769d01a365ab707794a4084392c824f54a7a6a7862f8c3d0892b283"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
+[[package]]
+name = "slab"
+version = "0.4.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c790de23124f9ab44544d7ac05d60440adc586479ce501c1d6d7da3cd8c9cf5"
+
+[[package]]
+name = "syn"
+version = "3.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d78c8dee4c7bf0e14673097256fed6142ce9d3b85a408189d07482442145823b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "typenum"
+version = "1.20.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6f5e870be6c3b371b77fe0ee0bafb859fa4964b4404c27de1d380043c4dda20"
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2c754d6c33795a1c324727428e5a7dedb5b06195f9890bdbcba760d3e246563"
+
+[[package]]
+name = "uuid"
+version = "1.28.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7cc1186384beb7dd8eedea376413fd654937285ea6c9cfbb928dc3043ea4b606"
+dependencies = [
+ "getrandom",
+ "js-sys",
+ "wasm-bindgen",
+]
+
+[[package]]
+name = "version_check"
+version = "0.9.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
+
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.129"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9bb54f33acc68fd454578d9820b0bde1a1a3d17aa17bb7b6595806d02886d409"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+ "rustversion",
+ "wasm-bindgen-macro",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.129"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e29d0c35b16e224a7eeb5cd2d25e3e1968fbd65604117b44d3b789d00ee8535"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.129"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f501a8bc3719dba86ef8ae4728879c08001bea749eb1333ac5b91e040e2a6b7"
+dependencies = [
+ "bumpalo",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.129"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "23f0c9c52aa7cd7d77769a4cfe2a9adb1b331f489a41d912ce14513d5ab995c6"
+dependencies = [
+ "unicode-ident",
+]
diff --git a/tools/uuid-v8/Cargo.toml b/tools/uuid-v8/Cargo.toml
new file mode 100644
index 000000000..d3169ce85
--- /dev/null
+++ b/tools/uuid-v8/Cargo.toml
@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: MPL-2.0
+[package]
+name = "estate-uuid-v8"
+version = "0.1.0"
+edition = "2021"
+license = "MPL-2.0"
+description = "ESTATE-UUID-V8 (ADR-008): profile T (time-ordered) and profile C (SHA-256 of domain:name) identifiers."
+repository = "https://github.com/hyperpolymath/standards"
+publish = false
+
+[lib]
+name = "estate_uuid_v8"
+path = "src/lib.rs"
+
+[[bin]]
+name = "uuid-v8"
+path = "src/main.rs"
+
+[dependencies]
+sha2 = "0.10"
+uuid = { version = "1.25", features = ["v7"] }
diff --git a/tools/uuid-v8/README.adoc b/tools/uuid-v8/README.adoc
new file mode 100644
index 000000000..f666f858e
--- /dev/null
+++ b/tools/uuid-v8/README.adoc
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: MPL-2.0
+= estate-uuid-v8
+
+The shared Rust implementation of the ESTATE-UUID-V8 generators in
+link:../../docs/decisions/ADR-008-uuid-v8-estate-standard.adoc[ADR-008]
+(phase P1, "shared profile T and C generators per estate language"). It
+produces the same ids as `scripts/uuid-v8.js`.
+
+[cols="1,3,2",options="header"]
+|===
+| Function | Produces | Use for
+| `profile_t()` | A library v7 with its version nibble set to `8`. Time-ordered, and strictly increasing within one process. | Records and events.
+| `profile_c(domain, name)` / `profile_c_bytes(domain, bytes)` | Bytes 0..15 of SHA-256(`domain ":" name`), version `8`, variant `10`. | Content ids. The name is often a value's JCS form.
+| `from_deed_body("domain:name")` | Profile C from a deed `#u8` body, split on the first `:`. | Deeds.
+| `from_v7(id)` | The profile T alias of a stored v7 id (the P2 nibble flip). | Reading old ids.
+|===
+
+`domain` must be registered, unique within the repository, non-empty
+printable ASCII (`0x21..=0x7e`), and free of `:`. A v8 value does not say
+which profile produced it, so the field holding it declares the profile.
+
+== Use
+
+[source,toml]
+----
+[dependencies]
+estate-uuid-v8 = { git = "https://github.com/hyperpolymath/standards", rev = "<commit>" }
+----
+
+Pin a commit, as with every estate git dependency. Profile T needs the
+`uuid` crate's v7 randomness, so on `wasm32-unknown-unknown` the caller
+supplies its own fallback.
+
+The command-line front end behaves like `scripts/uuid-v8.js`:
+`uuid-v8 t`, `uuid-v8 c <domain> <name>`, `uuid-v8 deed <domain:name>`.
+
+== Tests
+
+`cargo test` checks profile C against vectors from the independent
+`sha256sum` oracle in `scripts/tests/bun/uuid-v8-gen-test.sh`. It also
+checks the profile T layout, order and timestamp, and the domain rules.
+`scripts/tests/rust/uuid-v8-rs-test.sh` runs the binary against the same
+oracle, compares it with `scripts/uuid-v8.js` when bun is installed, and
+passes the output through `check-uuid-v8.sh --strict`. Both run in
+`deed-conformance.yml`.
diff --git a/tools/uuid-v8/src/lib.rs b/tools/uuid-v8/src/lib.rs
new file mode 100644
index 000000000..36bbffe7e
--- /dev/null
+++ b/tools/uuid-v8/src/lib.rs
@@ -0,0 +1,219 @@
+// SPDX-License-Identifier: MPL-2.0
+//! ESTATE-UUID-V8 generators (ADR-008,
+//! `docs/decisions/ADR-008-uuid-v8-estate-standard.adoc`): the shared Rust
+//! implementation of both profiles, matching `scripts/uuid-v8.js`.
+//!
+//! * **Profile T** — time-ordered. A library v7 with its version nibble set to
+//!   `8`, the only bit operation ADR-008 permits. Within one process the
+//!   `uuid` crate's shared v7 context keeps successive ids strictly
+//!   increasing, and the nibble flip preserves that order.
+//! * **Profile C** — content-derived. Bytes 0..15 of SHA-256(`domain ":" name`)
+//!   with the version nibble set to `8` and the variant bits to `10`. `domain`
+//!   is a registered, repository-unique, non-empty printable-ASCII string
+//!   without `:`, so the first `:` of the preimage always ends it. `name` is
+//!   unconstrained. Profile C ids are reproducible and not secret.
+//!
+//! A v8 value does not say which profile produced it; the field that holds it
+//! declares `profile T` or `profile C` in its type, schema or contract.
+
+use std::fmt;
+
+use sha2::{Digest, Sha256};
+use uuid::Uuid;
+
+/// Why an identifier could not be produced.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Error {
+    /// A profile C domain that is empty, contains `:`, or has a byte outside
+    /// printable ASCII (`0x21..=0x7e`).
+    InvalidDomain(String),
+    /// A deed `#u8` body with no `:` separating domain and name.
+    DeedBodyWithoutColon(String),
+    /// [`from_v7`] was given an id whose version is not 7.
+    NotVersion7(Uuid),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::InvalidDomain(d) => write!(
+                f,
+                "profile C domain must be non-empty printable ASCII without \":\" (got {d:?})"
+            ),
+            Error::DeedBodyWithoutColon(b) => write!(f, "#u8 body has no \":\" (got {b:?})"),
+            Error::NotVersion7(id) => write!(f, "expected a version 7 UUID (got {id})"),
+        }
+    }
+}
+
+impl std::error::Error for Error {}
+
+/// A fresh profile T id: a library v7 with its version nibble set to 8.
+pub fn profile_t() -> Uuid {
+    let mut bytes = *Uuid::now_v7().as_bytes();
+    set_version_8(&mut bytes);
+    Uuid::from_bytes(bytes)
+}
+
+/// The profile T alias of an existing v7 id (ADR-008 phase P2: "every v7 read
+/// is aliased to profile T by the nibble flip").
+pub fn from_v7(id: Uuid) -> Result<Uuid, Error> {
+    if id.get_version_num() != 7 {
+        return Err(Error::NotVersion7(id));
+    }
+    let mut bytes = *id.as_bytes();
+    set_version_8(&mut bytes);
+    Ok(Uuid::from_bytes(bytes))
+}
+
+/// The profile C id of (`domain`, `name`).
+pub fn profile_c(domain: &str, name: &str) -> Result<Uuid, Error> {
+    profile_c_bytes(domain, name.as_bytes())
+}
+
+/// The profile C id of (`domain`, `name`) for a name given as bytes, such as
+/// a value's JCS (RFC 8785) canonical form.
+pub fn profile_c_bytes(domain: &str, name: &[u8]) -> Result<Uuid, Error> {
+    validate_domain(domain)?;
+    let digest = Sha256::new()
+        .chain_update(domain.as_bytes())
+        .chain_update(b":")
+        .chain_update(name)
+        .finalize();
+    let mut bytes = [0u8; 16];
+    bytes.copy_from_slice(&digest[..16]);
+    set_version_8(&mut bytes);
+    bytes[8] = (bytes[8] & 0x3f) | 0x80; // variant 10
+    Ok(Uuid::from_bytes(bytes))
+}
+
+/// The profile C id named by a deed `#u8` body (`"domain:name"`). The body
+/// splits on its first `:`.
+pub fn from_deed_body(body: &str) -> Result<Uuid, Error> {
+    match body.split_once(':') {
+        Some((domain, name)) => profile_c(domain, name),
+        None => Err(Error::DeedBodyWithoutColon(body.to_owned())),
+    }
+}
+
+/// Check that `domain` is a valid profile C domain.
+pub fn validate_domain(domain: &str) -> Result<(), Error> {
+    let ok = !domain.is_empty()
+        && domain
+            .bytes()
+            .all(|b| (0x21..=0x7e).contains(&b) && b != b':');
+    if ok {
+        Ok(())
+    } else {
+        Err(Error::InvalidDomain(domain.to_owned()))
+    }
+}
+
+fn set_version_8(bytes: &mut [u8; 16]) {
+    bytes[6] = (bytes[6] & 0x0f) | 0x80;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::time::{SystemTime, UNIX_EPOCH};
+    use uuid::Variant;
+
+    /// Expected values from the independent oracle in
+    /// `scripts/tests/bun/uuid-v8-gen-test.sh` (sha256sum and shell nibble
+    /// arithmetic), not from this code.
+    const ORACLE: &[(&str, &str, &str)] = &[
+        (
+            "gv-clade-index",
+            "github.com/hyperpolymath/standards",
+            "b32d6be4-73ba-873e-9d61-e57f43c75cd1",
+        ),
+        (
+            "berrywiki-import",
+            "Main Page",
+            "c2be2559-9f9e-8131-aa58-1b0158cc2645",
+        ),
+        ("d", "", "394e0f7e-2f80-8af2-b682-28464ce30d58"),
+        ("d", "a:b c", "ca23a717-72b1-8d99-94c5-e32a4fda7acd"),
+        ("echidna-goal", "é✓", "939052b9-3381-8187-9199-1960e0a527a4"),
+    ];
+
+    #[test]
+    fn profile_c_matches_the_independent_oracle() {
+        for (domain, name, want) in ORACLE {
+            let got = profile_c(domain, name).unwrap();
+            assert_eq!(got.to_string(), *want, "{domain}:{name}");
+            assert_eq!(got.get_version_num(), 8);
+            assert_eq!(got.get_variant(), Variant::RFC4122);
+            assert_eq!(profile_c_bytes(domain, name.as_bytes()).unwrap(), got);
+        }
+    }
+
+    #[test]
+    fn deed_body_splits_on_the_first_colon() {
+        assert_eq!(
+            from_deed_body("d:a:b c").unwrap().to_string(),
+            "ca23a717-72b1-8d99-94c5-e32a4fda7acd"
+        );
+        assert!(matches!(
+            from_deed_body("no-colon"),
+            Err(Error::DeedBodyWithoutColon(_))
+        ));
+    }
+
+    #[test]
+    fn bad_domains_are_rejected() {
+        for domain in ["", "a:b", "a b", "tab\there", "é"] {
+            assert!(
+                matches!(profile_c(domain, "x"), Err(Error::InvalidDomain(_))),
+                "{domain:?} must be rejected"
+            );
+        }
+        assert!(validate_domain("!~").is_ok(), "0x21 and 0x7e are allowed");
+    }
+
+    #[test]
+    fn profile_t_is_version_8_variant_10_and_now() {
+        let now_ms = || {
+            SystemTime::now()
+                .duration_since(UNIX_EPOCH)
+                .unwrap()
+                .as_millis() as u64
+        };
+        let before = now_ms() - 1000;
+        let id = profile_t();
+        let after = now_ms() + 1000;
+        assert_eq!(id.get_version_num(), 8);
+        assert_eq!(id.get_variant(), Variant::RFC4122);
+        let b = id.as_bytes();
+        let ms = b[..6]
+            .iter()
+            .fold(0u64, |acc, &x| (acc << 8) | u64::from(x));
+        assert!((before..=after).contains(&ms), "timestamp {ms} is not now");
+    }
+
+    #[test]
+    fn profile_t_is_strictly_increasing_in_process() {
+        let ids: Vec<Uuid> = (0..10_000).map(|_| profile_t()).collect();
+        assert!(ids.windows(2).all(|w| w[0] < w[1]));
+    }
+
+    #[test]
+    fn from_v7_flips_only_the_version_nibble() {
+        let v7 = Uuid::now_v7();
+        let t = from_v7(v7).unwrap();
+        assert_eq!(t.get_version_num(), 8);
+        let (a, b) = (v7.as_bytes(), t.as_bytes());
+        for i in 0..16 {
+            if i == 6 {
+                assert_eq!(a[i] & 0x0f, b[i] & 0x0f);
+            } else {
+                assert_eq!(a[i], b[i]);
+            }
+        }
+        let v4 = Uuid::from_bytes([
+            0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x47, 0x77, 0x88, 0, 0, 0, 0, 0, 0, 0,
+        ]);
+        assert!(matches!(from_v7(v4), Err(Error::NotVersion7(_))));
+    }
+}
diff --git a/tools/uuid-v8/src/main.rs b/tools/uuid-v8/src/main.rs
new file mode 100644
index 000000000..e83c22dd8
--- /dev/null
+++ b/tools/uuid-v8/src/main.rs
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: MPL-2.0
+//! `uuid-v8` — command-line front end to `estate_uuid_v8`, with the same
+//! interface and exit codes as `scripts/uuid-v8.js`:
+//!
+//!   uuid-v8 t                   # profile T: time-ordered
+//!   uuid-v8 c <domain> <name>   # profile C: SHA-256(domain ":" name)
+//!   uuid-v8 deed <domain:name>  # profile C from a deed #u8 body
+
+use std::process::ExitCode;
+
+use estate_uuid_v8::{from_deed_body, profile_c, profile_t};
+
+fn main() -> ExitCode {
+    let args: Vec<String> = std::env::args().skip(1).collect();
+    let args: Vec<&str> = args.iter().map(String::as_str).collect();
+    let result = match args.as_slice() {
+        ["t"] => Ok(profile_t()),
+        ["c", domain, name] => profile_c(domain, name),
+        ["deed", body] => from_deed_body(body),
+        _ => {
+            eprintln!("usage: uuid-v8 t | c <domain> <name> | deed <domain:name>");
+            return ExitCode::from(2);
+        }
+    };
+    match result {
+        Ok(id) => {
+            println!("{id}");
+            ExitCode::SUCCESS
+        }
+        Err(e) => {
+            eprintln!("uuid-v8: {e}");
+            ExitCode::from(1)
+        }
+    }
+}