new: skip the git-init question inside existing repositories

src/new/git.rs

@@ -28,6 +28,23 @@ pub fn ensure_repository(dir: &Path, init: bool) -> Result<bool, Box<dyn std::er
     }
 }
 
+/// Whether `dir` sits inside a git work tree (its own or a parent's), in the
+/// spirit of `git rev-parse --is-inside-work-tree` (like
+/// [`crate::new::origin::GitOrigin::detect`]). Fail-soft: when `git` cannot
+/// be run or the probe fails, `dir` counts as outside — the caller keeps the
+/// behavior it would have without the probe, and the scaffold-time
+/// repository discovery in [`ensure_repository`] has the final word anyway.
+pub fn inside_work_tree(dir: &Path) -> bool {
+    let Ok(output) = std::process::Command::new("git")
+        .args(["rev-parse", "--is-inside-work-tree"])
+        .current_dir(dir)
+        .output()
+    else {
+        return false;
+    };
+    output.status.success() && String::from_utf8_lossy(&output.stdout).trim() == "true"
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -61,4 +78,22 @@ mod tests {
         assert!(!ensure_repository(&sub, true).unwrap());
         assert!(!sub.join(".git").exists());
     }
+
+    /// The probe answers like `git rev-parse --is-inside-work-tree`:
+    /// outside any repository it says no, inside one (at any depth, as a
+    /// skeleton mode scaffold would probe through its parent directory) it
+    /// says yes without touching the tree.
+    #[test]
+    fn inside_work_tree_follows_the_parent_repository() {
+        let dir = tempdir().unwrap();
+        assert!(!inside_work_tree(dir.path()));
+
+        git2::Repository::init(dir.path()).unwrap();
+        assert!(inside_work_tree(dir.path()));
+
+        let sub = dir.path().join("sub");
+        std::fs::create_dir(&sub).unwrap();
+        assert!(inside_work_tree(&sub));
+        assert!(!sub.join(".git").exists());
+    }
 }

src/new/questions.rs

@@ -23,6 +23,7 @@ use std::path::PathBuf;
 use indicatif::MultiProgress;
 
 use crate::new::detect::{self, Detection};
+use crate::new::git;
 use crate::new::options::{self, NewCli, NewOptions, SourceDir, SourceFormat, TemplateId};
 use crate::new::origin::GitOrigin;
 use crate::new::templates::{self, ProbeResult, ScaffoldOutcome};
@@ -467,8 +468,21 @@ async fn run_wizard(mut cli: NewCli) -> Result<NewOptions, Box<dyn Error>> {
         }
     }
 
-    // 14. Git init.
+    // 14. Git init — asked only when a git init would actually happen
+    //     (outside any repository, without `--no-git`). Inside an existing
+    //     git work tree there is nothing to initialize: the question is
+    //     skipped, the run assumes No and the scaffold logs its usual skip
+    //     (the .gitignore files are written regardless). The probe looks at
+    //     the packaged directory — or, for a skeleton, at the directory it
+    //     would be created in.
+    let probe_dir = cli.source.clone().unwrap_or_else(|| cwd.clone());
+    let inside_repo = cli.git && git::inside_work_tree(&probe_dir);
+    if git_init_answer(!cli.git, inside_repo).is_some() {
+        // `--no-git` already declined, or there is nothing to initialize.
+        cli.git = false;
+    } else {
         cli.git = prompt::confirm("Initialize a git repository?", cli.git)?;
+    }
 
     // Resolve through the same pipeline as the non-interactive path: one
     // source of truth for defaults and validation.
@@ -826,6 +840,16 @@ fn orig_origin_choices(origin: Option<&GitOrigin>) -> Vec<(String, &'static str)
     choices
 }
 
+/// The git-init answer when the question must not be asked: `Some(false)`
+/// both for `--no-git` (already declined) and inside an existing git work
+/// tree (nothing to initialize — the scaffold logs the skip and writes the
+/// `.gitignore` files anyway). `None` asks the wizard question, i.e.
+/// whenever a git init would actually happen (fresh skeleton or packaged
+/// directory outside any repository).
+fn git_init_answer(no_git: bool, inside_repo: bool) -> Option<bool> {
+    (no_git || inside_repo).then_some(false)
+}
+
 /// A `debian/watch` template for GitHub/GitLab-hosted projects; `None` when
 /// the homepage is not one of those hosts (the wizard skips the question).
 pub fn watch_template(homepage: Option<&str>) -> Option<String> {
@@ -1250,6 +1274,19 @@ mod tests {
         assert!(!summary_text(&opts(Tid::Go), Some("1.98.0")).contains("rust-toolchain"));
     }
 
+    /// The git-init question is only asked when a git init would actually
+    /// happen: inside an existing work tree it is skipped with the assumed
+    /// No (with or without `--no-git`), and `--no-git` has already answered
+    /// it on its own.
+    #[test]
+    fn git_init_question_decision() {
+        assert_eq!(git_init_answer(false, true), Some(false));
+        assert_eq!(git_init_answer(true, true), Some(false));
+        assert_eq!(git_init_answer(true, false), Some(false));
+        // Outside any repository without --no-git: the wizard asks.
+        assert_eq!(git_init_answer(false, false), None);
+    }
+
     #[test]
     fn answer_validators() {
         assert!(validate_revision_answer("1").is_ok());