diff --git a/.github/workflows/dart.yml b/.github/workflows/dart.yml
index c7cbd3a65..12c7e3787 100644
--- a/.github/workflows/dart.yml
+++ b/.github/workflows/dart.yml
@@ -55,7 +55,15 @@ jobs:
       - name: Set up nix
         uses: $/.github/actions/setup-nix
       - name: Generate production bindings and dry-run publish
-        run: nix develop .#dart -c ./payjoin-ffi/dart/contrib/prepare-publish.sh "$RUNNER_TEMP/payjoin-pub"
+        run: |
+          # Pull requests may change payjoin or payjoin-mailroom without a
+          # version bump, so they stage those crates from the checkout.
+          # Releases stage against crates.io, as consumers build them.
+          flags=()
+          if [[ $GITHUB_EVENT_NAME == pull_request ]]; then
+            flags+=(--core-from-revision)
+          fi
+          nix develop .#dart -c ./payjoin-ffi/dart/contrib/prepare-publish.sh "${flags[@]}" "$RUNNER_TEMP/payjoin-pub"
       # The release workflow publishes this exact stage, so it is archived
       # rather than regenerated in the publish job.
       - name: Archive the staged package
diff --git a/payjoin-ffi/dart/CONTRIBUTING.md b/payjoin-ffi/dart/CONTRIBUTING.md
index 2c84f7811..455284441 100644
--- a/payjoin-ffi/dart/CONTRIBUTING.md
+++ b/payjoin-ffi/dart/CONTRIBUTING.md
@@ -82,11 +82,12 @@ validates the archive with a publish dry run
    is seeded from `Cargo-recent.lock` and resolved against that revision,
    so consumers build the versions CI tested. A dependency fix reaches
    Dart consumers through `Cargo-recent.lock` and a new release. Staging
-   fetches the pinned commit from GitHub, so it must be pushed. When a
-   `payjoin` or `payjoin-mailroom` version that `payjoin-ffi` or
-   `payjoin-test-utils` requires is not on crates.io yet, staging takes
-   it from the same revision and writes an `UNPUBLISHED_CORE` marker,
-   which `contrib/publish.sh` refuses. Both the publish dry run and
+   fetches the pinned commit from GitHub, so it must be pushed. The
+   `payjoin` and `payjoin-mailroom` crates come from crates.io, except
+   with `--core-from-revision`, which pull requests use since they may
+   change those crates without a version bump. That option takes them
+   from the same revision and writes an `UNPUBLISHED_CORE` marker, which
+   `contrib/publish.sh` refuses. Both the publish dry run and
    publication use the staged package. For local checks:
 
    ```shell
diff --git a/payjoin-ffi/dart/contrib/prepare-publish.sh b/payjoin-ffi/dart/contrib/prepare-publish.sh
index bdda75c38..a6511a411 100755
--- a/payjoin-ffi/dart/contrib/prepare-publish.sh
+++ b/payjoin-ffi/dart/contrib/prepare-publish.sh
@@ -1,7 +1,12 @@
 #!/usr/bin/env bash
 set -euo pipefail
+core_from_revision=false
+if [[ ${1:-} == --core-from-revision ]]; then
+    core_from_revision=true
+    shift
+fi
 [ "$#" -eq 1 ] || {
-    echo "usage: prepare-publish.sh <new-package-dir>" >&2
+    echo "usage: prepare-publish.sh [--core-from-revision] <new-package-dir>" >&2
     exit 1
 }
 # Resolve before changing directories; the destination must not exist.
@@ -39,48 +44,31 @@ grep -Fq "rev = \"$revision\"" "$stage/native/Cargo.toml" || {
 
 # payjoin-ffi and payjoin-test-utils come from the pinned revision, but the
 # release crates they require, payjoin and payjoin-mailroom, come from
-# crates.io. Between a version bump of one of those and its crates.io
-# release, the lock below could not resolve it. Take such a crate from the
-# pinned revision instead so pull requests can still stage, and leave a
+# crates.io. A pull request can change those crates without a version bump,
+# so its payjoin-ffi may not build against what crates.io has. With
+# --core-from-revision, take them from the pinned revision too, and leave a
 # marker that publish.sh refuses: a published package must build against
 # crates its consumers can get from crates.io.
-source "$REPO_ROOT/contrib/release/crates.sh"
-# crates.io answers 404 for a version it does not have. Any other failure,
-# such as a rate limit or an outage, must stop here rather than read as
-# unpublished, or a release run would stage a package publish.sh refuses.
-crates_io_status() {
-    curl -sL --retry 3 -o /dev/null -w '%{http_code}' \
-        -H "User-Agent: rust-payjoin release tooling" \
-        "https://crates.io/api/v1/crates/$1/$2" || true
-}
-siblings="$(sibling_deps payjoin-ffi && sibling_deps payjoin-test-utils)"
-[[ $siblings == *payjoin$'\t'* ]] || {
-    echo "Could not read the payjoin version payjoin-ffi requires" >&2
-    exit 1
-}
-while IFS=$'\t' read -r dep req; do
-    version="${req#^}"
-    version="${version#=}"
-    status="$(crates_io_status "$dep" "$version")"
-    case $status in
-        200) continue ;;
-        404) ;;
-        *)
-            echo "Could not check $dep $version on crates.io (HTTP $status)" >&2
-            exit 1
-            ;;
-    esac
-    echo "==> $dep $version is not on crates.io; staging it from $revision"
-    cat >>"$stage/native/Cargo.toml" <<EOF
+if [[ $core_from_revision == true ]]; then
+    source "$REPO_ROOT/contrib/release/crates.sh"
+    siblings="$(sibling_deps payjoin-ffi && sibling_deps payjoin-test-utils)"
+    [[ $siblings == *payjoin$'\t'* ]] || {
+        echo "Could not read the payjoin version payjoin-ffi requires" >&2
+        exit 1
+    }
+    while IFS=$'\t' read -r dep _; do
+        echo "==> Staging $dep from $revision"
+        cat >>"$stage/native/Cargo.toml" <<EOF
 
-# Added by prepare-publish.sh: $dep $version is not on crates.io yet.
+# Added by prepare-publish.sh --core-from-revision.
 [patch.crates-io.$dep]
 git = "https://github.com/payjoin/rust-payjoin.git"
 rev = "$revision"
 EOF
-    printf '%s %s comes from %s, not crates.io\n' "$dep" "$version" \
-        "$revision" >>"$stage/UNPUBLISHED_CORE"
-done < <(sort -u <<<"$siblings")
+        printf '%s comes from %s, not crates.io\n' "$dep" "$revision" \
+            >>"$stage/UNPUBLISHED_CORE"
+    done < <(sort -u <<<"$siblings")
+fi
 
 # Ship the dependency graph this release was tested against; hook/build.dart
 # builds it with --locked. Seeding from the maintained lockfile keeps every