diff --git a/src/commands/git_ai_handlers.rs b/src/commands/git_ai_handlers.rs
index 99c153e9..a62c5e8c 100644
--- a/src/commands/git_ai_handlers.rs
+++ b/src/commands/git_ai_handlers.rs
@@ -782,6 +782,47 @@ fn handle_checkpoint(args: &[String]) {
 
     let checkpoint_start = std::time::Instant::now();
     let agent_tool = agent_run_result.as_ref().map(|r| r.agent_id.tool.clone());
+
+    let external_files: Vec<String> = agent_run_result
+        .as_ref()
+        .and_then(|r| {
+            let paths = if r.checkpoint_kind == CheckpointKind::Human {
+                r.will_edit_filepaths.as_ref()
+            } else {
+                r.edited_filepaths.as_ref()
+            };
+            paths.map(|p| {
+                let repo_workdir = repo.workdir().ok();
+                p.iter()
+                    .filter_map(|path| {
+                        let workdir = repo_workdir.as_ref()?;
+                        let path_buf = if std::path::Path::new(path).is_absolute() {
+                            std::path::PathBuf::from(path)
+                        } else {
+                            workdir.join(path)
+                        };
+                        if repo.path_is_in_workdir(&path_buf) {
+                            None
+                        } else {
+                            let abs = if std::path::Path::new(path).is_absolute() {
+                                path.clone()
+                            } else {
+                                workdir.join(path).to_string_lossy().to_string()
+                            };
+                            Some(abs)
+                        }
+                    })
+                    .collect::<Vec<_>>()
+            })
+        })
+        .unwrap_or_default();
+
+    let external_agent_base = if !external_files.is_empty() {
+        agent_run_result.as_ref().cloned()
+    } else {
+        None
+    };
+
     commands::git_hook_handlers::ensure_repo_level_hooks_for_checkpoint(&repo);
     let checkpoint_result = commands::checkpoint::run(
         &repo,
@@ -793,30 +834,100 @@ fn handle_checkpoint(args: &[String]) {
         agent_run_result,
         false,
     );
+    let local_checkpoint_failed = checkpoint_result.is_err();
     match checkpoint_result {
         Ok((_, files_edited, _)) => {
             let elapsed = checkpoint_start.elapsed();
             log_performance_for_checkpoint(files_edited, elapsed, checkpoint_kind);
             eprintln!("Checkpoint completed in {:?}", elapsed);
-
-            // Flush logs and metrics after checkpoint (skip for human checkpoints)
-            if checkpoint_kind != CheckpointKind::Human {
-                observability::spawn_background_flush();
-            }
         }
         Err(e) => {
             let elapsed = checkpoint_start.elapsed();
             eprintln!("Checkpoint failed after {:?} with error {}", elapsed, e);
             let context = serde_json::json!({
                 "function": "checkpoint",
-                "agent": agent_tool.unwrap_or_default(),
+                "agent": agent_tool.clone().unwrap_or_default(),
                 "duration": elapsed.as_millis(),
                 "checkpoint_kind": format!("{:?}", checkpoint_kind)
             });
             observability::log_error(&e, Some(context));
-            std::process::exit(0);
         }
     }
+
+    if !external_files.is_empty()
+        && let Some(base_result) = external_agent_base
+    {
+        let (repo_files, orphan_files) = group_files_by_repository(&external_files, None);
+
+        if !orphan_files.is_empty() {
+            eprintln!(
+                "Warning: {} cross-repo file(s) are not in any git repository and will be skipped",
+                orphan_files.len()
+            );
+        }
+
+        for (repo_workdir, (ext_repo, repo_file_paths)) in repo_files {
+            if !config.is_allowed_repository(&Some(ext_repo.clone())) {
+                continue;
+            }
+
+            let ext_user_name = match ext_repo.config_get_str("user.name") {
+                Ok(Some(name)) if !name.trim().is_empty() => name,
+                _ => "unknown".to_string(),
+            };
+
+            let mut modified = base_result.clone();
+            modified.repo_working_dir = Some(repo_workdir.to_string_lossy().to_string());
+            if base_result.checkpoint_kind == CheckpointKind::Human {
+                modified.will_edit_filepaths = Some(repo_file_paths);
+                modified.edited_filepaths = None;
+            } else {
+                modified.edited_filepaths = Some(repo_file_paths);
+                modified.will_edit_filepaths = None;
+            }
+
+            commands::git_hook_handlers::ensure_repo_level_hooks_for_checkpoint(&ext_repo);
+            match commands::checkpoint::run(
+                &ext_repo,
+                &ext_user_name,
+                checkpoint_kind,
+                false,
+                false,
+                false,
+                Some(modified),
+                false,
+            ) {
+                Ok((_, files_edited, _)) => {
+                    eprintln!(
+                        "Cross-repo checkpoint for {} completed ({} files)",
+                        repo_workdir.display(),
+                        files_edited
+                    );
+                }
+                Err(e) => {
+                    eprintln!(
+                        "Cross-repo checkpoint for {} failed: {}",
+                        repo_workdir.display(),
+                        e
+                    );
+                    let context = serde_json::json!({
+                        "function": "checkpoint",
+                        "repo": repo_workdir.to_string_lossy(),
+                        "checkpoint_kind": format!("{:?}", checkpoint_kind)
+                    });
+                    observability::log_error(&e, Some(context));
+                }
+            }
+        }
+    }
+
+    if checkpoint_kind != CheckpointKind::Human {
+        observability::spawn_background_flush();
+    }
+
+    if local_checkpoint_failed {
+        std::process::exit(0);
+    }
 }
 
 fn handle_ai_blame(args: &[String]) {
diff --git a/tests/multi_repo_workspace.rs b/tests/multi_repo_workspace.rs
index 0e2f49f5..774c9990 100644
--- a/tests/multi_repo_workspace.rs
+++ b/tests/multi_repo_workspace.rs
@@ -7,6 +7,12 @@
 //! 2. Grouping files by their containing repository
 //! 3. Handling submodules correctly (should be ignored in favor of parent repo)
 //! 4. Edge cases with nested git directories
+//! 5. Cross-repo checkpoints: AI edits from one repo to files in another repo
+
+#[macro_use]
+mod repos;
+use repos::test_file::ExpectedLineExt;
+use repos::test_repo::TestRepo;
 
 use git_ai::error::GitAiError;
 use git_ai::git::repository::{
@@ -910,3 +916,128 @@ fn test_repository_isolation() {
 
     cleanup_tmp_dir(&workspace);
 }
+
+#[test]
+fn test_cross_repo_checkpoint_creates_working_log_in_target_repo() {
+    let repo1 = TestRepo::new();
+    let repo2 = TestRepo::new();
+
+    let mut file = repo2.filename("test.txt");
+    file.set_contents(lines!["Line 1", "Line 2", "Line 3"]);
+    repo2.stage_all_and_commit("Initial commit").unwrap();
+
+    fs::write(
+        repo2.path().join("test.txt"),
+        "Line 1\nLine 2\nLine 3\nAI Line 1\nAI Line 2\n",
+    )
+    .unwrap();
+
+    let repo2_file_abs = repo2.canonical_path().join("test.txt");
+    let abs_path_str = repo2_file_abs.to_str().unwrap();
+
+    repo2
+        .git_ai_from_working_dir(
+            &repo1.canonical_path(),
+            &["checkpoint", "mock_ai", abs_path_str],
+        )
+        .unwrap();
+
+    let working_log = repo2.current_working_logs();
+    let ai_files = working_log.all_ai_touched_files().unwrap_or_default();
+    assert!(
+        !ai_files.is_empty(),
+        "Cross-repo checkpoint should create working log entries in the target repo (repo2), but found none. \
+         This means the checkpoint from repo1's working directory failed to write to repo2's working log."
+    );
+}
+
+#[test]
+fn test_cross_repo_checkpoint_ai_attribution_on_commit() {
+    let repo1 = TestRepo::new();
+    let repo2 = TestRepo::new();
+
+    let mut file = repo2.filename("test.txt");
+    file.set_contents(lines!["Line 1", "Line 2", "Line 3"]);
+    repo2.stage_all_and_commit("Initial commit").unwrap();
+
+    fs::write(
+        repo2.path().join("test.txt"),
+        "Line 1\nLine 2\nLine 3\nAI Line 1\nAI Line 2\n",
+    )
+    .unwrap();
+
+    let repo2_file_abs = repo2.canonical_path().join("test.txt");
+    let abs_path_str = repo2_file_abs.to_str().unwrap();
+
+    repo2
+        .git_ai_from_working_dir(
+            &repo1.canonical_path(),
+            &["checkpoint", "mock_ai", abs_path_str],
+        )
+        .unwrap();
+
+    let commit = repo2.stage_all_and_commit("AI edits from repo1").unwrap();
+
+    assert!(
+        !commit.authorship_log.attestations.is_empty(),
+        "Cross-repo AI edits should be attributed to AI, not human. \
+         The checkpoint was run from repo1's working directory for a file in repo2, \
+         but the commit in repo2 shows no AI attestations."
+    );
+}
+
+#[test]
+fn test_cross_repo_checkpoint_preserves_local_repo_checkpoint() {
+    let repo1 = TestRepo::new();
+    let repo2 = TestRepo::new();
+
+    let mut file1 = repo1.filename("local.txt");
+    file1.set_contents(lines!["Local 1", "Local 2"]);
+    repo1
+        .stage_all_and_commit("Initial commit in repo1")
+        .unwrap();
+
+    let mut file2 = repo2.filename("remote.txt");
+    file2.set_contents(lines!["Remote 1", "Remote 2"]);
+    repo2
+        .stage_all_and_commit("Initial commit in repo2")
+        .unwrap();
+
+    fs::write(
+        repo1.path().join("local.txt"),
+        "Local 1\nLocal 2\nAI local line\n",
+    )
+    .unwrap();
+    fs::write(
+        repo2.path().join("remote.txt"),
+        "Remote 1\nRemote 2\nAI remote line\n",
+    )
+    .unwrap();
+
+    let repo1_file_abs = repo1.canonical_path().join("local.txt");
+    let repo2_file_abs = repo2.canonical_path().join("remote.txt");
+
+    repo1
+        .git_ai_from_working_dir(
+            &repo1.canonical_path(),
+            &[
+                "checkpoint",
+                "mock_ai",
+                repo1_file_abs.to_str().unwrap(),
+                repo2_file_abs.to_str().unwrap(),
+            ],
+        )
+        .unwrap();
+
+    let repo1_commit = repo1.stage_all_and_commit("AI edits in repo1").unwrap();
+    assert!(
+        !repo1_commit.authorship_log.attestations.is_empty(),
+        "Local repo (repo1) should still have AI attestations when cross-repo files are also checkpointed"
+    );
+
+    let repo2_commit = repo2.stage_all_and_commit("AI edits in repo2").unwrap();
+    assert!(
+        !repo2_commit.authorship_log.attestations.is_empty(),
+        "Cross-repo (repo2) should also have AI attestations"
+    );
+}