feat(#1466): add sessions table + turn_stats.session_id capture for per-session stats

hive-ag3nt/src/events.rs

@@ -618,6 +618,15 @@ pub struct Bus {
     /// behavior. Atomic so the consumer can take-and-clear without a
     /// lock.
     skip_continue_once: Arc<AtomicBool>,
+    /// Current fresh-claude-session id (FK to `sessions.id`). Set by the
+    /// bin loop after minting a session row on a fresh start; stamped onto
+    /// every `turn_stats` row until the next fresh session. `None` before
+    /// the first fresh turn or when the stats db is unavailable.
+    session_id: Arc<Mutex<Option<i64>>>,
+    /// One-shot: `run_claude` flips this true when it suppresses
+    /// `--continue` (a fresh session). The bin loop takes-and-clears it
+    /// after the turn to decide whether to mint a new `sessions` row.
+    fresh_session: Arc<AtomicBool>,
     /// Per-turn tool-call counter. Reset by the bin loop between
     /// turns via `take_tool_calls`. Populated by `observe_stream` as
     /// the stdout pump parses each stream-json line. Powers the
@@ -691,6 +700,8 @@ impl Bus {
             last_cost_usage: Arc::new(Mutex::new(None)),
             rate_limited: Arc::new(AtomicBool::new(was_rate_limited)),
             skip_continue_once: Arc::new(AtomicBool::new(false)),
+            session_id: Arc::new(Mutex::new(None)),
+            fresh_session: Arc::new(AtomicBool::new(false)),
             tool_calls: Arc::new(Mutex::new(std::collections::HashMap::new())),
             last_turn_ended_unix: Arc::new(AtomicI64::new(0)),
             api_context_window: Arc::new(Mutex::new(None)),
@@ -727,6 +738,39 @@ impl Bus {
         self.skip_continue_once.swap(false, Ordering::SeqCst)
     }
 
+    /// Mark that the current turn started a fresh claude session.
+    /// `run_claude` calls this when it suppresses `--continue`.
+    pub fn mark_fresh_session(&self) {
+        self.fresh_session.store(true, Ordering::SeqCst);
+    }
+
+    /// Take + clear the fresh-session one-shot. The bin loop calls this
+    /// after the turn to decide whether to mint a new `sessions` row.
+    #[must_use]
+    pub fn take_fresh_session(&self) -> bool {
+        self.fresh_session.swap(false, Ordering::SeqCst)
+    }
+
+    /// Currently-active session id (FK to `sessions.id`), or `None`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the internal lock is poisoned.
+    #[must_use]
+    pub fn current_session_id(&self) -> Option<i64> {
+        *self.session_id.lock().unwrap()
+    }
+
+    /// Set the active session id after minting a `sessions` row on a
+    /// fresh start.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the internal lock is poisoned.
+    pub fn set_session_id(&self, id: Option<i64>) {
+        *self.session_id.lock().unwrap() = id;
+    }
+
     /// Currently-selected claude model name. Read on every turn so a
     /// `/model <name>` flip takes effect on the next turn.
     ///