CB-303 part 2: context_cap turn budget

bridged/src/main/java/dev/ltms/bridged/Bridged.java

@@ -65,7 +65,13 @@ public final class Bridged {
 
         // CB-301: authoritative session registry + lifecycle FSM on top of WorkerService.
         // CB-301-ext: worktree provisioning seam, optionally rooted at a configured directory.
-        SessionManager sessions = new SessionManager(workers, new GitWorktrees(cfg.worktreeRoot()));
+        // CB-303 part 2: context cap is opt-in and disabled (0) when absent/null.
+        int contextCap = 0;
+        if (cfg.lifecycle() != null && cfg.lifecycle().contextCap() != null
+                && cfg.lifecycle().contextCap() > 0) {
+            contextCap = cfg.lifecycle().contextCap();
+        }
+        SessionManager sessions = new SessionManager(workers, new GitWorktrees(cfg.worktreeRoot()), contextCap);
 
         // CB-303 part 1: idle-ttl reaper — only when configured, defaults to disabled.
         SessionReaper reaper = null;

bridged/src/main/java/dev/ltms/bridged/session/SessionManager.java

@@ -40,23 +40,35 @@ public final class SessionManager implements TurnListener {
     private final SecureRandom nonceRandom = new SecureRandom();
     private final AtomicLong nonceSeq = new AtomicLong();
     private final LongSupplier nowNanos;
+    private final int contextCap;
 
     /** Backward-compatible constructor: shared-tree sessions, production git seam. */
     public SessionManager(WorkerService workerService) {
-        this(workerService, new GitWorktrees(), System::nanoTime);
+        this(workerService, new GitWorktrees(), System::nanoTime, 0);
     }
 
     /** Backward-compatible constructor with an injectable worktree seam. */
     public SessionManager(WorkerService workerService, Worktrees worktrees) {
-        this(workerService, worktrees, System::nanoTime);
+        this(workerService, worktrees, System::nanoTime, 0);
     }
 
     /** Test constructor with an injectable clock. */
     public SessionManager(WorkerService workerService, Worktrees worktrees, LongSupplier nowNanos) {
+        this(workerService, worktrees, nowNanos, 0);
+    }
+
+    /** Production constructor with a configured context turn cap. */
+    public SessionManager(WorkerService workerService, Worktrees worktrees, int contextCap) {
+        this(workerService, worktrees, System::nanoTime, contextCap);
+    }
+
+    public SessionManager(WorkerService workerService, Worktrees worktrees, LongSupplier nowNanos,
+                          int contextCap) {
         this.workerService = workerService;
         this.worktrees = worktrees;
         this.presence = new PresenceBridge(this);
         this.nowNanos = nowNanos;
+        this.contextCap = contextCap;
     }
 
     /**
@@ -208,16 +220,40 @@ public final class SessionManager implements TurnListener {
         transitionByTerminal(terminalId, WorkerSession.State.SPAWNING, WorkerSession.State.READY);
     }
 
-    /** Lifecycle hook: a message was delivered into the worker — it is now busy on a turn. */
+    /**
+     * Lifecycle hook: a message was delivered into the worker — it is now busy on a turn.
+     * The turn count is bumped and the activity timestamp is refreshed. A {@code DONE} session
+     * can be re-delivered for multi-turn reuse until it is released.
+     */
     @Override
     public void onDelivered(String target) {
-        transitionByTerminal(target, WorkerSession.State.READY, WorkerSession.State.BUSY);
+        WorkerSession current = findByTerminal(target);
+        if (current == null) return;
+        if (current.state() != WorkerSession.State.READY && current.state() != WorkerSession.State.DONE) {
+            return;
+        }
+        long now = nowNanos.getAsLong();
+        WorkerSession updated = current.withState(WorkerSession.State.BUSY).bumpTurn(now);
+        if (replace(current, updated)) {
+            log.debug("session transitioned terminal={} pane={} {} -> BUSY turn={}",
+                    target, current.paneId(), current.state(), updated.turnCount());
+        }
     }
 
     /** Lifecycle hook: the worker's delegated turn completed successfully. */
     @Override
     public void onTurnComplete(String target) {
-        transitionByTerminal(target, WorkerSession.State.BUSY, WorkerSession.State.DONE);
+        WorkerSession current = findByTerminal(target);
+        if (current == null || current.state() != WorkerSession.State.BUSY) return;
+        long now = nowNanos.getAsLong();
+        WorkerSession updated = current.withState(WorkerSession.State.DONE).withActivity(now);
+        if (replace(current, updated)) {
+            log.debug("session transitioned terminal={} pane={} BUSY -> DONE turn={}",
+                    target, current.paneId(), updated.turnCount());
+        }
+        if (contextCap > 0 && updated.turnCount() >= contextCap) {
+            release(current.paneId());
+        }
     }
 
     /** Lifecycle hook: the worker's delegated turn failed. */