cli: add --stdin and --edit flags to jj commit

CHANGELOG.md

@@ -39,6 +39,13 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   directly as positional arguments, such as
   `jj bisect --range=..main -- cargo check --all-targets`.
 
+* `jj commit` now accepts `--stdin` to read the commit message from stdin,
+  matching the behavior of `jj describe`. This allows passing multi-line
+  messages without shell escaping issues.
+
+* `jj commit` now accepts `--edit` to open an editor after providing a message
+  via `--stdin` or `-m`, enabling two-stage message refinement.
+
 ### Fixed bugs
 
 * `jj metaedit --author-timestamp` twice with the same value no longer

cli/src/commands/commit.rs

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use std::io;
+use std::io::Read as _;
+
 use clap_complete::ArgValueCandidates;
 use clap_complete::ArgValueCompleter;
 use indoc::writedoc;
@@ -61,8 +64,25 @@ pub(crate) struct CommitArgs {
     )]
     tool: Option<String>,
     /// The change description to use (don't open editor)
-    #[arg(long = "message", short, value_name = "MESSAGE")]
+    #[arg(
+        long = "message",
+        short,
+        value_name = "MESSAGE",
+        conflicts_with = "stdin"
+    )]
     message_paragraphs: Vec<String>,
+    /// Read the change description from stdin
+    ///
+    /// Diff selection runs before we read stdin, so console-based diff editors
+    /// remain usable.
+    #[arg(long)]
+    stdin: bool,
+    /// Open an editor
+    ///
+    /// Forces an editor to open when using `--stdin` or `--message` to
+    /// allow the message to be edited afterwards.
+    #[arg(long)]
+    edit: bool,
     /// Put these paths in the first commit
     #[arg(
         value_name = "FILESETS",
@@ -167,18 +187,37 @@ new working-copy commit.
         commit_builder.set_author(new_author);
     }
 
-    let description = if !args.message_paragraphs.is_empty() {
-        let mut description = join_message_paragraphs(&args.message_paragraphs);
-        if !description.is_empty() {
+    let provided_description = if args.stdin {
+        let mut buffer = String::new();
+        io::stdin().read_to_string(&mut buffer)?;
+        Some(buffer)
+    } else if !args.message_paragraphs.is_empty() {
+        Some(join_message_paragraphs(&args.message_paragraphs))
+    } else {
+        None
+    };
+
+    let description = if let Some(mut description) = provided_description {
+        commit_builder.set_description(&description);
+        if args.edit || !description.is_empty() {
             // The first trailer would become the first line of the description.
             // Also, a commit with no description is treated in a special way in jujutsu: it
             // can be discarded as soon as it's no longer the working copy. Adding a
-            // trailer to an empty description would break that logic.
-            commit_builder.set_description(description);
+            // trailer to an empty description would break that logic unless the user
+            // explicitly opens the editor to review it.
             description = add_trailers(ui, &tx, &commit_builder)?;
         }
-        description
+        if args.edit {
+            commit_builder.set_description(&description);
+            let temp_commit = commit_builder.write_hidden()?;
+            let intro = "";
+            let template = description_template(ui, &tx, intro, &temp_commit)?;
+            edit_description(&text_editor, &template)?
+        } else {
+            description
+        }
     } else {
+        // No description provided, must use editor
         let description = add_trailers(ui, &tx, &commit_builder)?;
         commit_builder.set_description(description);
         let temp_commit = commit_builder.write_hidden()?;

cli/tests/test_commit_command.rs

@@ -568,18 +568,14 @@ fn test_commit_trailers() {
     ");
 
     let editor0 = std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap();
-    insta::assert_snapshot!(
-        format!("-----\n{editor0}-----\n"), @r#"
-    -----
+    insta::assert_snapshot!(editor0, @r#"
 
+Reviewed-by: [email protected]
 
-    Reviewed-by: [email protected]
-
-    JJ: Change ID: zsuskuln
-    JJ:
-    JJ: Lines starting with "JJ:" (like this one) will be removed.
-    -----
-    "#);
+JJ: Change ID: zsuskuln
+JJ:
+JJ: Lines starting with "JJ:" (like this one) will be removed.
+"#);
 
     let output = work_dir.run_jj(["log", "--no-graph", "-r@-", "-Tdescription"]);
     insta::assert_snapshot!(output, @r"
@@ -588,6 +584,92 @@ fn test_commit_trailers() {
     ");
 }
 
+#[test]
+fn test_commit_with_description_from_stdin() {
+    let test_env = TestEnvironment::default();
+    test_env.run_jj_in(".", ["git", "init", "repo"]).success();
+    let work_dir = test_env.work_dir("repo");
+
+    work_dir.write_file("file1", "foo\n");
+    let output = work_dir
+        .run_jj_with(|cmd| {
+            cmd.args(["commit", "--stdin"])
+                .write_stdin("Multi-line\n\ncommit message")
+        })
+        .success();
+    insta::assert_snapshot!(output);
+
+    let output = work_dir.run_jj(["log", "--no-graph", "-r@-", "-Tdescription"]);
+    insta::assert_snapshot!(output);
+}
+
+#[test]
+fn test_commit_with_empty_description_from_stdin() {
+    let test_env = TestEnvironment::default();
+    test_env.run_jj_in(".", ["git", "init", "repo"]).success();
+    let work_dir = test_env.work_dir("repo");
+
+    work_dir.write_file("file1", "foo\n");
+    let output = work_dir
+        .run_jj_with(|cmd| cmd.args(["commit", "--stdin"]).write_stdin(""))
+        .success();
+    insta::assert_snapshot!(get_log_output(&work_dir));
+    insta::assert_snapshot!(output);
+}
+
+#[test]
+fn test_commit_with_description_from_stdin_and_edit() {
+    let mut test_env = TestEnvironment::default();
+    let edit_script = test_env.set_up_fake_editor();
+    test_env.run_jj_in(".", ["git", "init", "repo"]).success();
+    let work_dir = test_env.work_dir("repo");
+
+    work_dir.write_file("file1", "foo\n");
+    std::fs::write(&edit_script, ["write\nedited message"].join("\0")).unwrap();
+    work_dir
+        .run_jj_with(|cmd| {
+            cmd.args(["commit", "--stdin", "--edit"])
+                .write_stdin("from stdin")
+        })
+        .success();
+
+    let output = work_dir.run_jj(["log", "--no-graph", "-r@-", "-Tdescription"]);
+    insta::assert_snapshot!(output);
+}
+
+#[test]
+fn test_commit_stdin_conflicts_with_message() {
+    let test_env = TestEnvironment::default();
+    test_env.run_jj_in(".", ["git", "init", "repo"]).success();
+    let work_dir = test_env.work_dir("repo");
+
+    let output = work_dir.run_jj_with(|cmd| {
+        cmd.args(["commit", "--stdin", "-m", "message"])
+            .write_stdin("stdin")
+    });
+    insta::assert_snapshot!(output);
+}
+
+#[test]
+fn test_commit_stdin_with_interactive() {
+    let mut test_env = TestEnvironment::default();
+    let diff_script = test_env.set_up_fake_diff_editor();
+    test_env.run_jj_in(".", ["git", "init", "repo"]).success();
+    let work_dir = test_env.work_dir("repo");
+
+    work_dir.write_file("file1", "foo\n");
+    std::fs::write(&diff_script, "dump JJ-INSTRUCTIONS instrs").unwrap();
+    let output = work_dir
+        .run_jj_with(|cmd| {
+            cmd.args(["commit", "--stdin", "--interactive"])
+                .write_stdin("from stdin")
+        })
+        .success();
+    insta::assert_snapshot!(output);
+    let log_output = work_dir.run_jj(["log", "--no-graph", "-r@-", "-Tdescription"]);
+    insta::assert_snapshot!(log_output);
+}
+
 #[must_use]
 fn get_log_output(work_dir: &TestWorkDir) -> CommandOutput {
     let template = r#"commit_id.short() ++ " " ++ description"#;