feat: Make triggers opt-in and fix inject submission

crates/pu-cli/src/commands/spawn.rs

@@ -25,6 +25,7 @@ pub async fn run(
     agent_args: Option<String>,
     plan_mode: bool,
     no_trigger: bool,
+    trigger: Option<String>,
     json: bool,
 ) -> Result<(), CliError> {
     daemon_ctrl::ensure_daemon(socket).await?;
@@ -73,6 +74,7 @@ pub async fn run(
             extra_args,
             plan_mode,
             no_trigger,
+            trigger,
         },
     )
     .await?;

crates/pu-cli/src/commands/trigger.rs

@@ -111,3 +111,25 @@ pub async fn run_delete(
     output::print_response(&resp, json)?;
     Ok(())
 }
+
+pub async fn run_assign(
+    socket: &Path,
+    agent_id: &str,
+    trigger_name: &str,
+    json: bool,
+) -> Result<(), CliError> {
+    daemon_ctrl::ensure_daemon(socket).await?;
+    let project_root = commands::cwd_string()?;
+    let resp = client::send_request(
+        socket,
+        &Request::AssignTrigger {
+            project_root,
+            agent_id: agent_id.to_string(),
+            trigger_name: trigger_name.to_string(),
+        },
+    )
+    .await?;
+    let resp = output::check_response(resp, json)?;
+    output::print_response(&resp, json)?;
+    Ok(())
+}

crates/pu-cli/src/main.rs

@@ -65,6 +65,9 @@ enum Commands {
         /// Disable event triggers for this agent
         #[arg(long)]
         no_trigger: bool,
+        /// Bind an idle trigger to this agent (name of trigger in .pu/triggers/)
+        #[arg(long, conflicts_with = "no_trigger")]
+        trigger: Option<String>,
         /// Output as JSON
         #[arg(long)]
         json: bool,
@@ -575,6 +578,16 @@ enum TriggerAction {
         #[arg(long)]
         json: bool,
     },
+    /// Assign a trigger to an idle agent
+    Assign {
+        /// Agent ID
+        agent_id: String,
+        /// Trigger name
+        trigger_name: String,
+        /// Output as JSON
+        #[arg(long)]
+        json: bool,
+    },
 }
 
 #[tokio::main]
@@ -608,11 +621,12 @@ async fn main() {
             agent_args,
             plan,
             no_trigger,
+            trigger,
             json,
         } => {
             commands::spawn::run(
                 &socket, prompt, agent, name, base, root, worktree, template, file, command, vars,
-                no_auto, agent_args, plan, no_trigger, json,
+                no_auto, agent_args, plan, no_trigger, trigger, json,
             )
             .await
         }
@@ -771,6 +785,11 @@ async fn main() {
             TriggerAction::Delete { name, scope, json } => {
                 commands::trigger::run_delete(&socket, &name, &scope, json).await
             }
+            TriggerAction::Assign {
+                agent_id,
+                trigger_name,
+                json,
+            } => commands::trigger::run_assign(&socket, &agent_id, &trigger_name, json).await,
         },
         Commands::Gate {
             event,

crates/pu-cli/src/output.rs

@@ -253,6 +253,18 @@ pub fn print_response(response: &Response, json_mode: bool) -> Result<(), CliErr
         Response::RenameResult { agent_id, name } => {
             println!("Renamed agent {} to {}", agent_id.bold(), name.green());
         }
+        Response::AssignTriggerResult {
+            agent_id,
+            trigger_name,
+            sequence_len,
+        } => {
+            println!(
+                "Assigned trigger {} to agent {} ({} steps)",
+                trigger_name.green(),
+                agent_id.bold(),
+                sequence_len
+            );
+        }
         Response::CreateWorktreeResult { worktree_id } => {
             println!("Created worktree {}", worktree_id.bold());
         }

crates/pu-core/src/protocol.rs

@@ -3,7 +3,7 @@ use serde::{Deserialize, Serialize};
 
 use crate::types::{AgentStatus, WorktreeEntry};
 
-pub const PROTOCOL_VERSION: u32 = 4;
+pub const PROTOCOL_VERSION: u32 = 5;
 
 /// Serde helper: encode `Vec<u8>` as hex in JSON for binary PTY data.
 mod hex_bytes {
@@ -66,6 +66,8 @@ pub enum Request {
         plan_mode: bool,
         #[serde(default)]
         no_trigger: bool,
+        #[serde(default)]
+        trigger: Option<String>,
     },
     Status {
         project_root: String,
@@ -127,6 +129,11 @@ pub enum Request {
         agent_id: String,
         name: String,
     },
+    AssignTrigger {
+        project_root: String,
+        agent_id: String,
+        trigger_name: String,
+    },
     CreateWorktree {
         project_root: String,
         #[serde(default)]
@@ -598,6 +605,11 @@ pub enum Response {
         agent_id: String,
         name: String,
     },
+    AssignTriggerResult {
+        agent_id: String,
+        trigger_name: String,
+        sequence_len: u32,
+    },
     CreateWorktreeResult {
         worktree_id: String,
     },
@@ -836,6 +848,7 @@ mod tests {
             extra_args: vec![],
             plan_mode: false,
             no_trigger: false,
+            trigger: None,
         };
         let json = serde_json::to_string(&req).unwrap();
         let parsed: Request = serde_json::from_str(&json).unwrap();
@@ -886,6 +899,7 @@ mod tests {
             extra_args: vec![],
             plan_mode: false,
             no_trigger: false,
+            trigger: None,
         };
         let json = serde_json::to_string(&req).unwrap();
         let parsed: Request = serde_json::from_str(&json).unwrap();
@@ -920,6 +934,7 @@ mod tests {
             extra_args: vec!["--model".into(), "opus".into()],
             plan_mode: false,
             no_trigger: false,
+            trigger: None,
         };
         let json = serde_json::to_string(&req).unwrap();
         let parsed: Request = serde_json::from_str(&json).unwrap();
@@ -946,6 +961,7 @@ mod tests {
             extra_args: vec![],
             plan_mode: true,
             no_trigger: false,
+            trigger: None,
         };
         let json = serde_json::to_string(&req).unwrap();
         let parsed: Request = serde_json::from_str(&json).unwrap();
@@ -955,6 +971,64 @@ mod tests {
         }
     }
 
+    #[test]
+    fn given_spawn_request_without_trigger_should_default_to_none() {
+        let json = r#"{"type":"spawn","project_root":"/test","prompt":"fix bug"}"#;
+        let req: Request = serde_json::from_str(json).unwrap();
+        match req {
+            Request::Spawn { trigger, .. } => assert!(trigger.is_none()),
+            _ => panic!("expected Spawn"),
+        }
+    }
+
+    #[test]
+    fn given_spawn_request_with_trigger_should_round_trip() {
+        let req = Request::Spawn {
+            project_root: "/test".into(),
+            prompt: "fix".into(),
+            agent: "claude".into(),
+            name: None,
+            base: None,
+            root: true,
+            worktree: None,
+            command: None,
+            no_auto: false,
+            extra_args: vec![],
+            plan_mode: false,
+            no_trigger: false,
+            trigger: Some("review-bot".into()),
+        };
+        let json = serde_json::to_string(&req).unwrap();
+        let parsed: Request = serde_json::from_str(&json).unwrap();
+        match parsed {
+            Request::Spawn { trigger, .. } => assert_eq!(trigger.unwrap(), "review-bot"),
+            _ => panic!("expected Spawn"),
+        }
+    }
+
+    #[test]
+    fn given_assign_trigger_request_should_round_trip() {
+        let req = Request::AssignTrigger {
+            project_root: "/test".into(),
+            agent_id: "ag-abc123".into(),
+            trigger_name: "review-bot".into(),
+        };
+        let json = serde_json::to_string(&req).unwrap();
+        let parsed: Request = serde_json::from_str(&json).unwrap();
+        match parsed {
+            Request::AssignTrigger {
+                project_root,
+                agent_id,
+                trigger_name,
+            } => {
+                assert_eq!(project_root, "/test");
+                assert_eq!(agent_id, "ag-abc123");
+                assert_eq!(trigger_name, "review-bot");
+            }
+            _ => panic!("expected AssignTrigger"),
+        }
+    }
+
     #[test]
     fn given_status_request_with_agent_id_should_round_trip() {
         let req = Request::Status {
@@ -1262,7 +1336,7 @@ mod tests {
 
     #[test]
     fn given_protocol_version_should_be_current() {
-        assert_eq!(PROTOCOL_VERSION, 4);
+        assert_eq!(PROTOCOL_VERSION, 5);
     }
 
     // --- GridCommand round-trips ---
@@ -1528,6 +1602,29 @@ mod tests {
         }
     }
 
+    #[test]
+    fn given_assign_trigger_result_should_round_trip() {
+        let resp = Response::AssignTriggerResult {
+            agent_id: "ag-abc".into(),
+            trigger_name: "review-bot".into(),
+            sequence_len: 3,
+        };
+        let json = serde_json::to_string(&resp).unwrap();
+        let parsed: Response = serde_json::from_str(&json).unwrap();
+        match parsed {
+            Response::AssignTriggerResult {
+                agent_id,
+                trigger_name,
+                sequence_len,
+            } => {
+                assert_eq!(agent_id, "ag-abc");
+                assert_eq!(trigger_name, "review-bot");
+                assert_eq!(sequence_len, 3);
+            }
+            _ => panic!("expected AssignTriggerResult"),
+        }
+    }
+
     // --- DeleteWorktree round-trips ---
 
     #[test]