Tell agents about stored git credentials; give Claude Code the user's git config

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/src/gitcreds.rs

@@ -53,6 +53,35 @@ pub fn identity_env(app: &App, user_id: &str) -> Vec<(String, String)> {
     env
 }
 
+/// What an agent needs to know about the stored git access (no secrets): git already has the
+/// credentials, so it must not look for them. None when nothing is stored.
+pub fn prompt_section(app: &App, user_id: &str) -> Option<String> {
+    render_prompt(&app.store.user_setting(user_id, "git").unwrap_or_default())
+}
+
+fn render_prompt(s: &GitSettings) -> Option<String> {
+    let creds: Vec<&GitCredential> = s.credentials.iter().filter(|c| !c.host.trim().is_empty() && !c.token.is_empty()).collect();
+    if creds.is_empty() {
+        return None;
+    }
+    let mut t = String::from("\n# Git access\nThe user has stored git credentials for these hosts (HTTPS):\n");
+    for c in &creds {
+        t.push_str(&format!("- {} (user {})\n", c.host.trim(), c.username.trim()));
+    }
+    t.push_str(
+        "git uses them automatically through its credential helper: `git clone`, `fetch`, `pull` and `push` with an https:// URL of these hosts just work, no login or token needed. \
+         Do NOT ask the user for a token and do NOT search the environment, config files, `gh`, SSH keys or the keychain for credentials – they are not there, and the command line shows none because git keeps them in its credential store. \
+         Use https:// remote URLs (SSH keys are not set up). \
+         For a REST API of such a host (pull requests, issues, releases) take the token straight from git without printing it, e.g. \
+         `curl -s -H \"Authorization: token $(printf 'protocol=https\\nhost=HOST\\n\\n' | git credential fill | sed -n 's/^password=//p')\" https://HOST/api/...` \
+         (GitHub: `Authorization: Bearer`). Never echo the token or write it into files, commits or your answer.\n",
+    );
+    if !s.name.trim().is_empty() || !s.email.trim().is_empty() {
+        t.push_str(&format!("Commits are made as {} <{}> automatically.\n", s.name.trim(), s.email.trim()));
+    }
+    Some(t)
+}
+
 pub fn home_of(app: &App, user: &User) -> PathBuf {
     app.data_dir().join("users").join(&user.username).join("home")
 }
@@ -159,6 +188,19 @@ pub fn merge(old: &GitSettings, mut new: GitSettings) -> GitSettings {
 mod tests {
     use super::*;
 
+    #[test]
+    fn prompt_names_hosts_but_never_tokens() {
+        assert!(render_prompt(&GitSettings::default()).is_none());
+        let settings = GitSettings { name: "Ann".into(), email: "ann@x.org".into(), credentials: vec![GitCredential { host: "git.x.org".into(), username: "ann".into(), token: "s3cret-token".into(), protocol: String::new() }] };
+        let p = render_prompt(&settings).unwrap();
+        println!("{p}");
+        assert!(p.contains("git.x.org (user ann)") && p.contains("git credential fill") && p.contains("Ann <ann@x.org>"));
+        assert!(!p.contains("s3cret-token"));
+        // Entries without a token are not offered.
+        let none = GitSettings { credentials: vec![GitCredential { host: "h".into(), username: "u".into(), ..Default::default() }], ..Default::default() };
+        assert!(render_prompt(&none).is_none());
+    }
+
     #[test]
     fn keeps_masked_tokens() {
         let old = GitSettings { credentials: vec![GitCredential { host: "git.x".into(), username: "me".into(), token: "secret".into(), protocol: String::new() }], ..Default::default() };