fix: add session-heartbeat and session-end CLI commands for hooks

- Add top-level `session-heartbeat` command (silent, touches session file)
- Add top-level `session-end` command (silent, removes session file)
- Add `Heartbeat` variant to SessionCommands enum
- Required by global Claude Code hooks in ~/.claude/settings.json

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/blue-cli/src/main.rs

@@ -133,6 +133,14 @@ enum Commands {
         #[arg(long)]
         tool: Option<String>,
     },
+
+    /// Session heartbeat (silent, used by hooks)
+    #[command(name = "session-heartbeat")]
+    SessionHeartbeat,
+
+    /// Session end (silent, used by hooks)
+    #[command(name = "session-end")]
+    SessionEnd,
 }
 
 #[derive(Subcommand)]
@@ -328,6 +336,9 @@ enum SessionCommands {
 
     /// Show session status
     Status,
+
+    /// Record session heartbeat (used by hooks)
+    Heartbeat,
 }
 
 #[derive(Subcommand)]
@@ -533,6 +544,24 @@ async fn main() -> Result<()> {
         Some(Commands::Guard { path, tool }) => {
             handle_guard_command(&path, tool.as_deref()).await?;
         }
+        Some(Commands::SessionHeartbeat) => {
+            // Silent heartbeat - touch session file if it exists
+            let cwd = std::env::current_dir()?;
+            let session_file = cwd.join(".blue").join("session");
+            if session_file.exists() {
+                if let Ok(content) = std::fs::read_to_string(&session_file) {
+                    let _ = std::fs::write(&session_file, content);
+                }
+            }
+        }
+        Some(Commands::SessionEnd) => {
+            // Silent session end - remove session file if it exists
+            let cwd = std::env::current_dir()?;
+            let session_file = cwd.join(".blue").join("session");
+            if session_file.exists() {
+                let _ = std::fs::remove_file(&session_file);
+            }
+        }
     }
 
     Ok(())
@@ -1253,6 +1282,20 @@ async fn handle_session_command(command: SessionCommands) -> Result<()> {
                 }
             }
         }
+
+        SessionCommands::Heartbeat => {
+            // Silent heartbeat - just touch the session file to update activity
+            let cwd = std::env::current_dir()?;
+            let session_file = cwd.join(".blue").join("session");
+
+            if session_file.exists() {
+                // Touch file by reading and writing back (updates mtime)
+                if let Ok(content) = std::fs::read_to_string(&session_file) {
+                    let _ = std::fs::write(&session_file, content);
+                }
+            }
+            // Silent success - no output for hooks
+        }
     }
 
     Ok(())