diff --git a/packages/rust/Cargo.toml b/packages/rust/Cargo.toml
index 91b439190..256b6403e 100644
--- a/packages/rust/Cargo.toml
+++ b/packages/rust/Cargo.toml
@@ -19,8 +19,14 @@ repository.workspace = true
 # `tests/` is the integration suite -- excluded so test files never ship in the
 # published `.crate` (enforced by the `packaging` gate in CI). Inline unit tests
 # stay (they are `#[cfg(test)]` modules inside `src/`, not separate files).
+# The fragment dirs are repo inputs -- one file per change, assembled into
+# nothing and read by no crate consumer. They need naming here because cargo
+# ships whatever is not excluded; npm and maturin drop theirs structurally, via
+# an allowlist and the wheel layout respectively.
 exclude = [
     "tests/",
+    "changelog.d/",
+    "migrations.d/",
     "docs/.vitepress",
     "docs/.claude",
     "docs/tests",
diff --git a/packages/rust/changelog.d/2026-08-20-crate-excludes-fragment-dirs.md b/packages/rust/changelog.d/2026-08-20-crate-excludes-fragment-dirs.md
new file mode 100644
index 000000000..6febda98c
--- /dev/null
+++ b/packages/rust/changelog.d/2026-08-20-crate-excludes-fragment-dirs.md
@@ -0,0 +1,9 @@
+**Fixed** — the published `.crate` archive no longer ships `changelog.d/` and
+`migrations.d/`. `[package].exclude` named `tests/` and the VitePress tooling
+under `docs/` but not the fragment dirs, and cargo ships whatever is not
+excluded, so every release carried 60 fragment files no crate consumer reads —
+more than half the archive's entries (119 files → 59).
+
+No API, CLI or behavior change; the crate is smaller and its file list now
+matches the npm package (an allowlist) and the wheel (maturin's layout), which
+already dropped their fragments structurally.
diff --git a/packages/rust/tests/crate_contents.rs b/packages/rust/tests/crate_contents.rs
new file mode 100644
index 000000000..6b80c17a9
--- /dev/null
+++ b/packages/rust/tests/crate_contents.rs
@@ -0,0 +1,89 @@
+//! What the published `.crate` archive ships.
+//!
+//! `changelog.d/` and `migrations.d/` are repo *inputs* -- one fragment file
+//! per change, assembled by nothing and read by no consumer of the crate.
+//! The npm `files` allowlist and maturin's wheel layout keep them out of
+//! their artifacts structurally; cargo ships everything not named in
+//! `[package].exclude`, so the crate needs the patterns spelled out.
+//!
+//! Asserted against `cargo package --list` -- the archive's own manifest --
+//! rather than against the `exclude` patterns, so a pattern that parses but
+//! matches nothing still fails here.
+
+use std::process::Command;
+
+/// Every path `cargo package` would write into the `.crate` archive.
+///
+/// `--allow-dirty` because the question is what the *working tree* would
+/// ship: without it cargo refuses outright the moment a packaged file is
+/// uncommitted, so editing `exclude` and re-running would abort before
+/// listing anything -- failing for a reason that has nothing to do with the
+/// assertions below.
+fn packaged_paths() -> Vec<String> {
+    let output = Command::new(env!("CARGO"))
+        .args([
+            "package",
+            "--manifest-path",
+            concat!(env!("CARGO_MANIFEST_DIR"), "/Cargo.toml"),
+            "--list",
+            "--allow-dirty",
+        ])
+        .output()
+        .expect("cargo package --list should run");
+
+    assert!(
+        output.status.success(),
+        "cargo package --list failed: {}",
+        String::from_utf8_lossy(&output.stderr)
+    );
+
+    String::from_utf8(output.stdout)
+        .expect("cargo package --list emits utf-8")
+        .lines()
+        .map(str::to_string)
+        .collect()
+}
+
+/// Archive paths under `prefix`.
+fn shipped_under(prefix: &str) -> Vec<String> {
+    packaged_paths()
+        .into_iter()
+        .filter(|path| path.starts_with(prefix))
+        .collect()
+}
+
+/// Guards the two assertions below against a vacuous pass: a `--list` that
+/// silently returned nothing would otherwise satisfy every "does not ship"
+/// check in this file.
+#[test]
+fn crate_archive_ships_the_library_source() {
+    let paths = packaged_paths();
+
+    assert!(
+        paths.iter().any(|p| p == "src/lib.rs"),
+        "expected src/lib.rs in the archive, got {} paths: {paths:?}",
+        paths.len()
+    );
+}
+
+#[test]
+fn crate_archive_omits_changelog_fragments() {
+    let shipped = shipped_under("changelog.d/");
+
+    assert!(
+        shipped.is_empty(),
+        "changelog fragments are repo inputs and must not ship; \
+         add `changelog.d/` to [package].exclude. Shipped: {shipped:?}"
+    );
+}
+
+#[test]
+fn crate_archive_omits_migration_fragments() {
+    let shipped = shipped_under("migrations.d/");
+
+    assert!(
+        shipped.is_empty(),
+        "migration fragments are repo inputs and must not ship; \
+         add `migrations.d/` to [package].exclude. Shipped: {shipped:?}"
+    );
+}