Commits of agents carry a co-author trailer naming the model

A git wrapper (docker/git-coauthor -> /usr/local/lib/codecraft/bin/git) adds
--trailer "$CODECRAFT_COMMIT_TRAILER" right after the commit subcommand; the
agent shell puts it first on PATH and sets the trailer in the script itself
(works inside the sandbox, which clears the environment). Default text:
"Co-Authored-By: {model} ({provider}) via CodeCraft" (server.commit_trailer,
Settings -> General; empty = off). Git skips duplicates (amend, model wrote it).

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

server/src/config.rs

@@ -307,8 +307,13 @@ pub struct ServerConfig {
     /// Bearer token for GET /metrics (Prometheus); empty = /metrics disabled.
     #[serde(skip_serializing_if = "String::is_empty")]
     pub metrics_token: String,
+    /// Trailer added to every git commit an agent makes ({model}, {provider}, {model_id});
+    /// empty = off.
+    pub commit_trailer: String,
 }
 
+pub const DEFAULT_COMMIT_TRAILER: &str = "Co-Authored-By: {model} ({provider}) via CodeCraft";
+
 impl Default for ServerConfig {
     fn default() -> Self {
         Self {
@@ -327,6 +332,7 @@ impl Default for ServerConfig {
             max_upload_mb: 500,
             update_url: "https://git.familie-zink.org/api/v1/repos/zink/codecraft/releases/latest".into(),
             metrics_token: String::new(),
+            commit_trailer: DEFAULT_COMMIT_TRAILER.into(),
         }
     }
 }

server/src/tools/bash.rs

@@ -135,7 +135,7 @@ impl Tool for Bash {
 /// The bash command for a script, sandboxed for non-admin users.
 pub fn shell_command(ctx: &ToolCtx, command: &str) -> std::result::Result<Command, ToolOutput> {
     // stderr of every command (not just the last one) goes into the output.
-    let script = format!("exec 2>&1\n{command}");
+    let script = format!("exec 2>&1\n{}{command}", commit_attribution(ctx));
     Ok(match &ctx.sandbox {
         Some(spec) => {
             if !crate::sandbox::available() {
@@ -161,6 +161,36 @@ pub fn shell_command(ctx: &ToolCtx, command: &str) -> std::result::Result<Comman
     })
 }
 
+/// Directory with the git wrapper that adds the co-author trailer to commits.
+fn git_wrapper_dir() -> String {
+    std::env::var("CODECRAFT_GIT_WRAPPER").unwrap_or_else(|_| "/usr/local/lib/codecraft/bin".into())
+}
+
+/// Shell lines that make `git commit` in this command carry the co-author trailer of
+/// the session's model (see docker/git-coauthor). Set in the script itself, so it
+/// works inside the sandbox (which clears the environment) too.
+fn commit_attribution(ctx: &ToolCtx) -> String {
+    let template = ctx.app.config().server.commit_trailer.clone();
+    let dir = git_wrapper_dir();
+    if template.trim().is_empty() || !std::path::Path::new(&dir).join("git").exists() {
+        return String::new();
+    }
+    let Ok(session) = ctx.app.session(&ctx.session_id) else { return String::new() };
+    let (provider, model_id) = session.model.split_once('/').unwrap_or(("", session.model.as_str()));
+    let name = ctx.app.registry().resolve(&session.model).ok().and_then(|(_, m)| m.name).filter(|n| !n.trim().is_empty()).unwrap_or_else(|| model_id.to_string());
+    let trailer = commit_trailer(&template, &name, provider, model_id);
+    format!("export PATH={}:\"$PATH\" CODECRAFT_COMMIT_TRAILER={}\n", shell_quote(&dir), shell_quote(&trailer))
+}
+
+/// The trailer text for a model ("Co-Authored-By: DeepSeek V4.1 Flash (opencode-go) via CodeCraft").
+pub fn commit_trailer(template: &str, model: &str, provider: &str, model_id: &str) -> String {
+    template.replace("{model}", model).replace("{provider}", provider).replace("{model_id}", model_id).replace(['\n', '\r'], " ").trim().to_string()
+}
+
+fn shell_quote(s: &str) -> String {
+    format!("'{}'", s.replace('\'', "'\\''"))
+}
+
 fn tail(s: &str, max: usize) -> String {
     if s.len() <= max {
         return s.to_string();
@@ -171,3 +201,18 @@ fn tail(s: &str, max: usize) -> String {
     }
     s[start..].to_string()
 }
+
+#[cfg(test)]
+mod commit_tests {
+    use super::*;
+
+    #[test]
+    fn commit_trailer_text() {
+        assert_eq!(
+            commit_trailer(crate::config::DEFAULT_COMMIT_TRAILER, "DeepSeek V4.1 Flash", "opencode-go", "deepseek-v4.1-flash"),
+            "Co-Authored-By: DeepSeek V4.1 Flash (opencode-go) via CodeCraft"
+        );
+        assert_eq!(commit_trailer("By {model_id}\nx", "M", "p", "m-1"), "By m-1 x");
+        assert_eq!(shell_quote("it's"), "'it'\\''s'");
+    }
+}