feat(cli): add helpers::git_run with stderr capture + context bail

crates/relicario-cli/src/helpers.rs

@@ -55,6 +55,37 @@ pub fn git_command(repo: &Path, args: &[&str]) -> Command {
     cmd
 }
 
+/// Run `git <args>` in `repo` with the same hardening as `git_command`,
+/// capturing stdout/stderr and reproducing them on failure so the caller
+/// sees git's exact diagnostic instead of just a verb.
+///
+/// `context` should be a short caller-supplied label like `"commit add: <id>"`
+/// or `"sync: git push"`; it prefixes the bail message so the failing call is
+/// identifiable from the error alone.
+///
+/// Trade-off vs. `git_command(...).status()`: this captures the child's stderr
+/// (so live progress disappears during long-running fetches/pushes) but the
+/// captured chunk is replayed verbatim on failure. The win is that
+/// non-interactive callers (tests, hooks, CI, redirected stdout) finally see
+/// pre-receive rejections, signing-key prompts, and dirty-tree complaints
+/// instead of one-line "git X failed" bails. Use `git_command` directly when
+/// live streaming is required.
+pub fn git_run(repo: &Path, args: &[&str], context: &str) -> Result<()> {
+    let output = git_command(repo, args)
+        .output()
+        .with_context(|| format!("{context}: failed to spawn git"))?;
+    if !output.status.success() {
+        if !output.stdout.is_empty() {
+            eprint!("{}", String::from_utf8_lossy(&output.stdout));
+        }
+        if !output.stderr.is_empty() {
+            eprint!("{}", String::from_utf8_lossy(&output.stderr));
+        }
+        bail!("{context}: git failed ({})", output.status);
+    }
+    Ok(())
+}
+
 /// Format a Unix-seconds timestamp as an ISO-8601 UTC string.
 /// Audit M11: replaces the old `now_iso8601` helper that actually returned
 /// a numeric string.
@@ -220,6 +251,24 @@ mod tests {
         assert_eq!(sanitize_for_commit("emoji \u{1F4AA}"), "emoji \u{1F4AA}");
     }
 
+    #[test]
+    fn git_run_bails_with_context_on_failure() {
+        // Empty tempdir — `git status` will fail with "not a git repository".
+        let tmp = TempDir::new().unwrap();
+        let err = git_run(tmp.path(), &["status"], "test_ctx").unwrap_err();
+        let msg = format!("{err}");
+        assert!(msg.contains("test_ctx"), "context not in error: {msg}");
+        assert!(msg.contains("git failed"), "missing failure marker: {msg}");
+    }
+
+    #[test]
+    fn git_run_succeeds_for_a_zero_exit_command() {
+        // `git --version` always succeeds and is independent of cwd.
+        let tmp = TempDir::new().unwrap();
+        git_run(tmp.path(), &["--version"], "version probe")
+            .expect("git --version should succeed");
+    }
+
     #[test]
     fn humanize_age_buckets() {
         assert_eq!(humanize_age(0), "just now");