feat(difftool): add difftool subcommand

git-branchless-opts/Cargo.toml

@@ -11,3 +11,4 @@ clap = { version = "4.3.19", features = ["derive"] }
 clap_mangen = "0.2.12"
 itertools = "0.11.0"
 lib = { package = "git-branchless-lib", version = "0.7.0", path = "../git-branchless-lib" }
+scm-record = { version = "0.1.0", path = "../scm-record", features = ["scm-diff-editor"] }

git-branchless-opts/src/lib.rs

@@ -426,6 +426,10 @@ pub enum Command {
     /// report.
     BugReport,
 
+    /// Use the partial commit selector UI as a Git-compatible difftool; see
+    /// git-difftool(1) for more information on Git difftools.
+    Difftool(scm_record::scm_diff_editor::Opts),
+
     /// Run internal garbage collection.
     Gc,
 

git-branchless/Cargo.toml

@@ -50,6 +50,9 @@ path-slash = "0.2.1"
 rayon = "1.7.0"
 regex = "1.9.1"
 rusqlite = { version = "0.29.0", features = ["bundled"] }
+scm-record = { version = "0.1.0", path = "../scm-record", features = [
+  "scm-diff-editor",
+] }
 thiserror = "1.0.44"
 tracing = "0.1.37"
 tracing-chrome = "0.6.0"
@@ -117,6 +120,3 @@ name = "test_undo"
 
 [[test]]
 name = "test_wrap"
-
-
-

git-branchless/src/commands/mod.rs

@@ -12,6 +12,7 @@ mod wrap;
 use git_branchless_invoke::CommandContext;
 use lib::core::rewrite::MergeConflictRemediation;
 
+use lib::util::ExitCode;
 use lib::{core::gc, util::EyreExitOr};
 
 use git_branchless_opts::{
@@ -43,6 +44,17 @@ fn command_main(ctx: CommandContext, opts: Opts) -> EyreExitOr<()> {
 
         Command::BugReport => bug_report::bug_report(&effects, &git_run_info)?,
 
+        Command::Difftool(opts) => {
+            let result = scm_record::scm_diff_editor::scm_diff_editor_main(opts);
+            match result {
+                Ok(()) | Err(scm_record::scm_diff_editor::Error::Cancelled) => Ok(()),
+                Err(err) => {
+                    eprintln!("Error: {err}");
+                    Err(ExitCode(1))
+                }
+            }
+        }
+
         Command::Switch { switch_options } => {
             git_branchless_navigation::switch(&effects, &git_run_info, &switch_options)?
         }

git-branchless/tests/test_init.rs

@@ -693,6 +693,9 @@ fn test_install_man_pages() -> eyre::Result<()> {
     git\-branchless\-bug\-report(1)
     Gather information about recent operations to upload as part of a bug report
     .TP
+    git\-branchless\-difftool(1)
+    Use the partial commit selector UI as a Git\-compatible difftool; see git\-difftool(1) for more information on Git difftools
+    .TP
     git\-branchless\-gc(1)
     Run internal garbage collection
     .TP