diff --git a/.github/workflows/quality.yml b/.github/workflows/quality.yml
index 882bd3d..a8cc614 100644
--- a/.github/workflows/quality.yml
+++ b/.github/workflows/quality.yml
@@ -19,7 +19,7 @@ jobs:
         include:
           - os: ubuntu-24.04
             timeout: timeout
-          - os: macos-14
+          - os: macos-15
             timeout: gtimeout
     runs-on: ${{ matrix.os }}
     timeout-minutes: 5
@@ -27,7 +27,7 @@ jobs:
       - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803
         with:
           persist-credentials: false
-      - if: matrix.os == 'macos-14'
+      - if: matrix.os == 'macos-15'
         run: brew install coreutils
         timeout-minutes: 2
       - run: ${{ matrix.timeout }} -k 5 120 rustup toolchain install 1.95 --profile minimal
@@ -38,14 +38,14 @@ jobs:
       - run: ${{ matrix.timeout }} -k 5 270 cargo +1.95 nextest run --locked
       - run: ${{ matrix.timeout }} -k 5 60 cargo +1.95 test --manifest-path fixtures/handoff/Cargo.toml --locked --tests
       - run: ${{ matrix.timeout }} -k 5 60 cargo +1.95 test --manifest-path examples/spendcheck/Cargo.toml --locked --tests
-      - if: matrix.os == 'macos-14'
+      - if: matrix.os == 'macos-15'
         run: shasum -a256 target/debug/allstack > target/debug/allstack.sha256
-      - if: matrix.os == 'macos-14'
+      - if: matrix.os == 'macos-15'
         run: git rev-parse HEAD > target/debug/allstack.commit
-      - if: matrix.os == 'macos-14'
+      - if: matrix.os == 'macos-15'
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f
         with:
-          name: allstack-macos-14
+          name: allstack-macos-15
           path: |
             target/debug/allstack
             target/debug/allstack.sha256
diff --git a/src/domain.rs b/src/domain.rs
index f0c76ca..4f9420f 100644
--- a/src/domain.rs
+++ b/src/domain.rs
@@ -362,3 +362,27 @@ pub fn spec_path_valid(path: &str) -> bool {
             .split('/')
             .all(|part| !part.is_empty() && part != ".." && !part.starts_with('.'))
 }
+
+/// The managed commit message. The run marker joins the message's closing
+/// trailer block, because git reads trailers only from the last paragraph and a
+/// repository may require its own (`Release-note:`, `Signed-off-by:`).
+pub fn managed_commit_message(message: &str, run_id: &str) -> String {
+    let message = message.trim_end();
+    let marker = format!("Allstack-Run: {run_id}");
+    let closes_with_trailers = message
+        .rsplit_once("\n\n")
+        .is_some_and(|(_, last)| last.lines().all(is_trailer));
+    if closes_with_trailers {
+        format!("{message}\n{marker}")
+    } else {
+        format!("{message}\n\n{marker}")
+    }
+}
+
+fn is_trailer(line: &str) -> bool {
+    line.split_once(": ").is_some_and(|(key, value)| {
+        !key.is_empty()
+            && !value.trim().is_empty()
+            && key.chars().all(|c| c.is_ascii_alphanumeric() || c == '-')
+    })
+}
diff --git a/src/infrastructure/runtime.rs b/src/infrastructure/runtime.rs
index eb4f78c..a581102 100644
--- a/src/infrastructure/runtime.rs
+++ b/src/infrastructure/runtime.rs
@@ -9,7 +9,9 @@ use super::{
 };
 use crate::{
     application::ports::{Platform, Start},
-    domain::{Policy, Publication, Run, Stage, Verification, WorkflowSelection},
+    domain::{
+        Policy, Publication, Run, Stage, Verification, WorkflowSelection, managed_commit_message,
+    },
 };
 use anyhow::{Context, Result, ensure};
 use serde_json::{Value, json};
@@ -316,7 +318,8 @@ impl Platform for Runtime {
         if count == 1 {
             args.push("--amend");
         }
-        args.extend(["-m", message, "-m", &marker]);
+        let full_message = managed_commit_message(message, &run.id);
+        args.extend(["-m", &full_message]);
         git::call(&self.state, &self.repo, &args)?;
         git::clean(&self.state, &self.repo)?;
         git::call(&self.state, &self.repo, &["rev-parse", "HEAD"])
diff --git a/tests/domain.rs b/tests/domain.rs
index 225b19f..54ceb06 100644
--- a/tests/domain.rs
+++ b/tests/domain.rs
@@ -1,5 +1,26 @@
 mod common;
-use allstack::domain::{Event, Host, Policy, Stage, validate_transition};
+use allstack::domain::{Event, Host, Policy, Stage, managed_commit_message, validate_transition};
+
+#[test]
+fn the_run_marker_joins_the_closing_trailer_block() {
+    let message = "feat(x): add y\n\nBody.\n\nRelease-note: Users can y.\n";
+    assert_eq!(
+        managed_commit_message(message, "run-1"),
+        "feat(x): add y\n\nBody.\n\nRelease-note: Users can y.\nAllstack-Run: run-1"
+    );
+}
+
+#[test]
+fn the_run_marker_starts_its_own_block_after_prose_or_a_bare_subject() {
+    assert_eq!(
+        managed_commit_message("fix: add y\n\nA body line.", "run-1"),
+        "fix: add y\n\nA body line.\n\nAllstack-Run: run-1"
+    );
+    assert_eq!(
+        managed_commit_message("fix: add y", "run-1"),
+        "fix: add y\n\nAllstack-Run: run-1"
+    );
+}
 
 #[test]
 fn stale_host_and_unknown_action_cannot_execute() {
diff --git a/tests/workspace.rs b/tests/workspace.rs
index a9f0107..611218c 100644
--- a/tests/workspace.rs
+++ b/tests/workspace.rs
@@ -49,7 +49,8 @@ impl Fixture {
                 .map(String::from)
                 .collect(),
             cwd: self.repo.clone(),
-            seconds: 10,
+            // The large-checkout case stages 10,010 files in one call.
+            seconds: 60,
             environment: BTreeMap::new(),
             input: None,
             directory: self.state.join("process"),