diff --git a/docs/guide_mma.md b/docs/guide_mma.md
index 72592b02..6e6f3be0 100644
--- a/docs/guide_mma.md
+++ b/docs/guide_mma.md
@@ -99,28 +99,35 @@ class TrackDAG:
 
 **`get_ready_tasks()`**: Returns tickets where `status == 'todo'` AND all `depends_on` have `status == 'completed'`. Missing dependencies are treated as NOT completed (fail-safe).
 
-**`has_cycle()`**: Classic DFS cycle detection using visited set + recursion stack:
+**`has_cycle()`**: Iterative DFS cycle detection using an explicit stack of `(node_id, is_backtracking)` tuples plus a `path` set (no recursion):
 
 ```python
 def has_cycle(self) -> bool:
-    visited = set()
-    rec_stack = set()
-    def is_cyclic(ticket_id):
-        if ticket_id in rec_stack: return True    # Back edge = cycle
-        if ticket_id in visited: return False      # Already explored
-        visited.add(ticket_id)
-        rec_stack.add(ticket_id)
-        for neighbor in ticket.depends_on:
-            if is_cyclic(neighbor): return True
-        rec_stack.remove(ticket_id)
+    with get_monitor().scope("dag_has_cycle"):
+        visited = set()
+        for start_ticket in self.tickets:
+            if start_ticket.id in visited:
+                continue
+            stack = [(start_ticket.id, False)]  # (id, is_backtracking)
+            path  = set()
+            while stack:
+                node_id, is_backtracking = stack.pop()
+                if is_backtracking:
+                    path.remove(node_id)
+                    continue
+                if node_id in path:    return True      # back-edge -> cycle
+                if node_id in visited: continue
+                visited.add(node_id)
+                path.add(node_id)
+                stack.append((node_id, True))           # post-visit marker
+                ticket = self.ticket_map.get(node_id)
+                if ticket:
+                    for neighbor_id in ticket.depends_on:
+                        stack.append((neighbor_id, False))
         return False
-    for ticket in self.tickets:
-        if ticket.id not in visited:
-            if is_cyclic(ticket.id): return True
-    return False
 ```
 
-**`topological_sort()`**: Calls `has_cycle()` first — raises `ValueError` if cycle found. Standard DFS post-order topological sort. Returns list of ticket ID strings in dependency order.
+**`topological_sort()`**: **Kahn's algorithm** (BFS-based, in-degree counter), not DFS post-order. Cycle detection is implicit — if `len(result) < len(self.tickets)` after the BFS drain, a `ValueError("Dependency cycle detected")` is raised. Returns a list of ticket ID strings in dependency order.
 
 ### ExecutionEngine
 
@@ -132,10 +139,10 @@ class ExecutionEngine:
 ```
 
 **`tick()`** — the heartbeat. On each call:
-1. Queries `dag.get_ready_tasks()` for eligible tickets.
-2. If `auto_queue` is enabled: non-`step_mode` tasks are automatically promoted to `in_progress`.
-3. `step_mode` tasks remain in `todo` until `approve_task()` is called.
-4. Returns the list of ready tasks.
+1. Calls `dag.cascade_blocks()` to propagate `blocked` status from any blocked ticket to its transitive `todo` dependents.
+2. Returns `dag.get_ready_tasks()` — the list of tickets that are `todo` with all dependencies `completed`.
+
+**`tick()` does NOT promote tickets to `in_progress`**. The auto-promotion (`status = "in_progress"`) happens in the **caller** — `ConductorEngine.run()` at `src/multi_agent_conductor.py` — not in `tick()`. `auto_queue` is therefore a parameter that the `ConductorEngine` consults in its own loop; `ExecutionEngine.tick()` itself only returns the ready list. Step-mode approval also happens in `ConductorEngine.run()` via `approve_task()`; the engine never moves a `todo` ticket on its own.
 
 **`approve_task(task_id)`**: Manually transitions `todo` → `in_progress` if all dependencies are met.
 
@@ -174,22 +181,34 @@ The Tier 2 orchestrator. Owns the execution loop that drives tickets through the
 
 ```python
 class ConductorEngine:
-    def __init__(self, track: Track, event_queue=None, auto_queue=False):
+    def __init__(
+        self,
+        track: Track,
+        event_queue: Optional[events.AsyncEventQueue] = None,
+        auto_queue: bool = False,
+        max_workers: int = 4,
+    ):
         self.track = track
         self.event_queue = event_queue
         self.tier_usage = {
             "Tier 1": {"input": 0, "output": 0, "model": "gemini-3.1-pro-preview", "tool_preset": None, "persona": None},
-            "Tier 2": {"input": 0, "output": 0, "model": "gemini-3-flash-preview", "tool_preset": None, "persona": None},
-            "Tier 3": {"input": 0, "output": 0, "model": "gemini-2.5-flash-lite", "tool_preset": None, "persona": None},
-            "Tier 4": {"input": 0, "output": 0, "model": "gemini-2.5-flash-lite", "tool_preset": None, "persona": None},
+            "Tier 2": {"input": 0, "output": 0, "model": "gemini-3-flash-preview",  "tool_preset": None, "persona": None},
+            "Tier 3": {"input": 0, "output": 0, "model": "gemini-2.5-flash-lite",   "tool_preset": None, "persona": None},
+            "Tier 4": {"input": 0, "output": 0, "model": "gemini-2.5-flash-lite",   "tool_preset": None, "persona": None},
         }
-        self.dag = TrackDAG(self.track.tickets)
+        self.dag    = TrackDAG(self.track.tickets)
         self.engine = ExecutionEngine(self.dag, auto_queue=auto_queue)
-        self.pool = WorkerPool(max_workers=max_workers)
-        self._abort_events: dict[str, threading.Event] = {}
-        self._pause_event: threading.Event = threading.Event()
+        self.pool   = WorkerPool(max_workers=max_workers)
+        self._workers_lock   = threading.Lock()
+        self._active_workers: dict[str, threading.Thread] = {}
+        self._abort_events:   dict[str, threading.Event]    = {}
+        self._pause_event:    threading.Event               = threading.Event()
+        self._tier_usage_lock = threading.Lock()
+        self._dirty:          bool = True
 ```
 
+`max_workers` is **NOT** read from `config.toml` by `ConductorEngine` itself — it is supplied by the caller. The 3 call sites in `AppController` (at `src/app_controller.py:4132-4133`, `4145-4146`, `4223-4224`) all read `config.toml` → `[mma].max_workers` and pass it in. The default in the constructor signature is 4.
+
 **Per-tier `tier_usage` schema** (each tier entry):
 
 | Key | Type | Purpose |