fix(dispatcher+watcher): never auto-dispatch into dedicated sessions

Observed: tasks from filesecure/.agent-queue/inbox and SecuScan/
.agent-queue/inbox were being routed into ccl-1-conformvault and
ccl-2-scanyze whenever those sessions happened to be idle. Those are
the operator's manual interactive Claude sessions, not dispatch
targets — the auto-dispatch was (a) hijacking a Claude instance the
operator was using and (b) triggering /exit via the watcher's
completion path when the side-task finished, kicking the operator out
mid-conversation.

findFreeSession was iterating Pool.Dedicated before the autonomous
pool, so any idle dedicated session was the first candidate.

- Dispatcher.findFreeSession: remove the Dedicated loop entirely.
  Auto-dispatch is now pool-only (ccl-auto-11..20).
- Watcher.completeSession: defense-in-depth — even if a dedicated
  session ever ends up in "working" state, it is no longer /exit'd;
  just marked idle. Pool /exit behaviour unchanged (context recycle).
- Tests: new TestFindFreeSessionSkipsDedicated proves the routing;
  3 existing tests rewritten to use the autonomous pool instead of
  relying on Dedicated as a fake pool.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/dispatcher/dispatcher_test.go

@@ -85,20 +85,19 @@ func TestModelForPriority(t *testing.T) {
 // TestFindFreeSessionSkipsFailed verifies that recently-failed sessions are skipped.
 func TestFindFreeSessionSkipsFailed(t *testing.T) {
 	tc := newMockTmux()
+	tc.sessions["sess-0"] = true
 	tc.sessions["sess-1"] = true
-	tc.sessions["sess-2"] = true
 
 	s := state.New("")
+	s.SetFailed("sess-0")
 	s.SetIdle("sess-1")
-	s.SetFailed("sess-2")
 
 	d := &Dispatcher{
 		tmux:  tc,
 		state: s,
 		config: &config.Config{
 			Pool: config.PoolConfig{
-				Dedicated:  []config.DedicatedSession{{Name: "sess-1"}, {Name: "sess-2"}},
-				Autonomous: config.AutonomousConfig{Max: 0},
+				Autonomous: config.AutonomousConfig{Prefix: "sess-", Max: 2},
 			},
 		},
 		logger: log.Default(),
@@ -113,28 +112,57 @@ func TestFindFreeSessionSkipsFailed(t *testing.T) {
 // TestFindFreeSessionMissingTmux skips sessions not in tmux.
 func TestFindFreeSessionMissingTmux(t *testing.T) {
 	tc := newMockTmux()
-	// sess-1 missing from tmux, sess-2 present and idle.
-	tc.sessions["sess-2"] = true
+	// sess-0 missing from tmux, sess-1 present and idle.
+	tc.sessions["sess-1"] = true
 
 	s := state.New("")
+	s.SetIdle("sess-0")
 	s.SetIdle("sess-1")
-	s.SetIdle("sess-2")
 
 	d := &Dispatcher{
 		tmux:  tc,
 		state: s,
 		config: &config.Config{
 			Pool: config.PoolConfig{
-				Dedicated:  []config.DedicatedSession{{Name: "sess-1"}, {Name: "sess-2"}},
-				Autonomous: config.AutonomousConfig{Max: 0},
+				Autonomous: config.AutonomousConfig{Prefix: "sess-", Max: 2},
 			},
 		},
 		logger: log.Default(),
 	}
 
 	got := d.findFreeSession()
-	if got != "sess-2" {
-		t.Errorf("expected sess-2, got %q", got)
+	if got != "sess-1" {
+		t.Errorf("expected sess-1, got %q", got)
+	}
+}
+
+// TestFindFreeSessionSkipsDedicated verifies that dedicated sessions are
+// NEVER returned by the auto-dispatch path, even when idle. Those host the
+// operator's manual interactive work and must stay untouched.
+func TestFindFreeSessionSkipsDedicated(t *testing.T) {
+	tc := newMockTmux()
+	tc.sessions["ccl-1-conformvault"] = true
+	tc.sessions["sess-0"] = true
+
+	s := state.New("")
+	s.SetIdle("ccl-1-conformvault")
+	s.SetIdle("sess-0")
+
+	d := &Dispatcher{
+		tmux:  tc,
+		state: s,
+		config: &config.Config{
+			Pool: config.PoolConfig{
+				Dedicated:  []config.DedicatedSession{{Name: "ccl-1-conformvault"}},
+				Autonomous: config.AutonomousConfig{Prefix: "sess-", Max: 1},
+			},
+		},
+		logger: log.Default(),
+	}
+
+	got := d.findFreeSession()
+	if got != "sess-0" {
+		t.Errorf("expected pool sess-0 (dedicated must be skipped), got %q", got)
 	}
 }
 
@@ -149,20 +177,19 @@ func TestDispatchProject(t *testing.T) {
 	os.WriteFile(taskPath, []byte(taskContent), 0644)
 
 	tc := newMockTmux()
-	tc.sessions["free-sess"] = true
+	tc.sessions["pool-0"] = true
 	// Return ❯ prompt on first CapturePaneTail call (Claude is ready).
-	tc.paneOutput["free-sess"] = "❯ "
+	tc.paneOutput["pool-0"] = "❯ "
 
 	s := state.New("")
-	s.SetIdle("free-sess")
+	s.SetIdle("pool-0")
 
 	d := &Dispatcher{
 		tmux:  tc,
 		state: s,
 		config: &config.Config{
 			Pool: config.PoolConfig{
-				Dedicated:  []config.DedicatedSession{{Name: "free-sess", Project: dir}},
-				Autonomous: config.AutonomousConfig{Max: 0},
+				Autonomous: config.AutonomousConfig{Prefix: "pool-", Max: 1},
 			},
 		},
 		logger: log.Default(),
@@ -170,7 +197,7 @@ func TestDispatchProject(t *testing.T) {
 
 	d.dispatchProject(inbox)
 
-	if st := s.GetSession("free-sess"); st == nil || st.State != "working" {
+	if st := s.GetSession("pool-0"); st == nil || st.State != "working" {
 		t.Errorf("expected session working after dispatch, got %v", st)
 	}