diff --git a/lib/crates/fabro-acp/src/command.rs b/lib/crates/fabro-acp/src/command.rs
index 834c0daab..0244654e6 100644
--- a/lib/crates/fabro-acp/src/command.rs
+++ b/lib/crates/fabro-acp/src/command.rs
@@ -37,11 +37,7 @@ impl AcpCommand {
 
     #[must_use]
     pub fn to_shell_command(&self) -> String {
-        std::iter::once(self.program.to_string_lossy().into_owned())
-            .chain(self.args.iter().cloned())
-            .map(|part| fabro_sandbox::shell_quote(&part))
-            .collect::<Vec<_>>()
-            .join(" ")
+        render_command(&self.program, &self.args)
     }
 }
 
@@ -123,11 +119,15 @@ fn parse_acp_command(raw: &str) -> Result<AcpCommand, AcpCommandError> {
         return Err(AcpCommandError::UnsupportedTransport);
     };
 
+    let program = stdio.command;
+    let args = stdio.args;
+    let display = render_command(&program, &args);
+
     Ok(AcpCommand {
-        display: raw.to_string(),
-        program: stdio.command,
-        args:    stdio.args,
-        env:     stdio
+        display,
+        program,
+        args,
+        env: stdio
             .env
             .into_iter()
             .map(|env| (env.name, env.value))
@@ -135,6 +135,14 @@ fn parse_acp_command(raw: &str) -> Result<AcpCommand, AcpCommandError> {
     })
 }
 
+fn render_command(program: &Path, args: &[String]) -> String {
+    std::iter::once(program.to_string_lossy().into_owned())
+        .chain(args.iter().cloned())
+        .map(|part| fabro_sandbox::shell_quote(&part))
+        .collect::<Vec<_>>()
+        .join(" ")
+}
+
 fn reject_non_stdio_json_transport(raw: &str) -> Result<(), AcpCommandError> {
     let trimmed = raw.trim_start();
     if !trimmed.starts_with('{') {
@@ -228,6 +236,20 @@ mod tests {
         assert_eq!(command.env().get("MODE").map(String::as_str), Some("test"));
     }
 
+    #[test]
+    fn json_stdio_acp_command_display_omits_env_contents() {
+        let raw = r#"{"type":"stdio","name":"fake","command":"agent","args":["--flag","two words"],"env":[{"name":"OPENAI_API_KEY","value":"secret-key"}]}"#;
+        let command = resolve_acp_command(Provider::OpenAi, Some(raw)).unwrap();
+
+        assert_eq!(
+            command.env().get("OPENAI_API_KEY").map(String::as_str),
+            Some("secret-key")
+        );
+        assert_eq!(command.to_string(), "agent --flag 'two words'");
+        assert!(!command.to_string().contains("secret-key"));
+        assert!(!command.to_string().contains("OPENAI_API_KEY"));
+    }
+
     #[test]
     fn non_stdio_acp_command_is_rejected() {
         let raw = r#"{"type":"http","name":"remote","url":"https://example.test/acp"}"#;
diff --git a/lib/crates/fabro-workflow/src/handler/llm/acp.rs b/lib/crates/fabro-workflow/src/handler/llm/acp.rs
index aecbea6c7..f43379147 100644
--- a/lib/crates/fabro-workflow/src/handler/llm/acp.rs
+++ b/lib/crates/fabro-workflow/src/handler/llm/acp.rs
@@ -337,11 +337,12 @@ fn acp_error_to_workflow(error: AcpError) -> Error {
 #[cfg(test)]
 mod tests {
     use std::collections::HashMap;
-    use std::sync::Arc;
+    use std::sync::{Arc, Mutex};
 
     use fabro_agent::{LocalSandbox, Sandbox, shell_quote};
     use fabro_graphviz::graph::{AttrValue, Node};
     use fabro_model::Provider;
+    use fabro_types::EventBody;
     use tokio_util::sync::CancellationToken;
 
     use super::AgentAcpBackend;
@@ -504,6 +505,71 @@ mod tests {
         assert!(matches!(err, crate::error::Error::Cancelled));
     }
 
+    #[tokio::test]
+    async fn acp_started_event_omits_json_command_env_values() {
+        let tempdir = tempfile::tempdir().unwrap();
+        let script_path = tempdir.path().join("fake_acp_agent.py");
+        tokio::fs::write(&script_path, fake_agent_script())
+            .await
+            .unwrap();
+
+        let raw_command = serde_json::json!({
+            "type": "stdio",
+            "name": "fake",
+            "command": "python3",
+            "args": [script_path.to_string_lossy()],
+            "env": [
+                {"name": "OPENAI_API_KEY", "value": "secret-key"}
+            ],
+        })
+        .to_string();
+        let mut node = Node::new("work");
+        node.attrs.insert(
+            "provider".to_string(),
+            AttrValue::String("openai".to_string()),
+        );
+        node.attrs
+            .insert("backend".to_string(), AttrValue::String("acp".to_string()));
+        node.attrs
+            .insert("acp_command".to_string(), AttrValue::String(raw_command));
+
+        let backend = AgentAcpBackend::new_from_env("fake-acp".to_string(), Provider::OpenAi);
+        let sandbox: Arc<dyn Sandbox> = Arc::new(LocalSandbox::new(tempdir.path().to_path_buf()));
+        let emitter = Arc::new(Emitter::default());
+        let events = Arc::new(Mutex::new(Vec::new()));
+        emitter.on_event({
+            let events = Arc::clone(&events);
+            move |event| events.lock().unwrap().push(event.clone())
+        });
+
+        backend
+            .run(
+                &node,
+                "write hello",
+                &Context::new(),
+                None,
+                &emitter,
+                &sandbox,
+                None,
+                CancellationToken::new(),
+            )
+            .await
+            .unwrap();
+
+        let events = events.lock().unwrap();
+        let command = events
+            .iter()
+            .find_map(|event| match &event.body {
+                EventBody::AgentAcpStarted(props) => Some(props.command.as_str()),
+                _ => None,
+            })
+            .expect("ACP started event should be emitted");
+        assert!(command.contains("python3"));
+        assert!(command.contains("fake_acp_agent.py"));
+        assert!(!command.contains("OPENAI_API_KEY"));
+        assert!(!command.contains("secret-key"));
+    }
+
     fn fake_agent_script() -> &'static str {
         r#"
 import json