diff --git a/docs/Architecture-Build-Spec.md b/docs/Architecture-Build-Spec.md
index a6f8bc6..69b5669 100644
--- a/docs/Architecture-Build-Spec.md
+++ b/docs/Architecture-Build-Spec.md
@@ -159,13 +159,21 @@ come back to something. Components throughout this document refer to them.
   arrive is a safe point, with one exception: switching is refused while intents
   are unresolved (A2). That keeps every pending intent owned by the active work
   item, so boot reconciliation (A3) stays single-item.
-- **The operator can always switch; the agent may switch on its own in one case.**
-  When the active work item is waiting on the operator (an open gate, a pending
-  question, or a halt in `AWAIT_INPUT`) and other work items are ready, the agent
-  switches to one of them and posts a notice naming both items and why it chose
-  that one. An alert must not sit for hours behind an unanswered prompt. The agent
-  never switches away from an item that is working. The item it left stays
-  waiting; switching answers nothing on its behalf.
+- **The operator can always switch; the agent may switch on its own in two cases,**
+  when other work items are ready:
+  - *The active item is waiting on the operator* (an open gate, a pending question,
+    or a halt in `AWAIT_INPUT`). An alert must not sit for hours behind an
+    unanswered prompt. The item it left stays waiting; switching answers nothing
+    on its behalf.
+  - *The active item has closed* (completed or abandoned). Ready work should not
+    sit behind an idle agent until the operator notices.
+
+  Either way, it posts a notice naming both items and why it chose that one. The
+  agent never switches away from an item that is working.
+- **A parked item is ready when the agent can act on it without the operator:** it
+  has not started yet (a duty finding, a ticket), or intake arrived while it was
+  parked that answers what it was waiting for (an approval, an answer, a review
+  comment). An item still waiting on the operator, with nothing new, is not ready.
 - **The model chooses which ready item to switch to.** This is one of the few
   judgments it is trusted with outright, because choosing grants nothing: every
   item still meets its own gates, and a poor choice costs time, not safety.
@@ -456,7 +464,7 @@ by replaying the operational trail:
   |---|---|
   | `state.transition` | `from`, `to`, `project` |
   | `intent.begin` / `intent.commit` / `intent.abort` | `intent_id`, `kind` |
-  | `work_item.switch` | `from`, `to`, `reason`, `chosen_by` (`model` / `fallback` / `operator`) |
+  | `work_item.switch` | `from` (parked or closed item, or `null`), `to`, `reason`, `chosen_by` (`model` / `fallback` / `operator`) |
   | `gate.open` / `gate.approve` / `gate.reject` | `gate`, `rev`, `channel` |
   | `boot.reconcile` | `action`, per-intent verdicts |
   | `schema.migrate` | `from_version`, `to_version` |
@@ -890,8 +898,9 @@ PR_OPEN
 
 ### B2. Requirements
 
-- **One active project at a time** (park-and-switch, 0.2). Operator selects it;
-  other projects stay parked at their last position and resume where they left off.
+- **One active project at a time** (park-and-switch, 0.2). The operator selects it,
+  or the agent switches on its own under 0.2's rules; other projects stay parked at
+  their last position and resume where they left off.
 - **Operator commands** (over transport): `use <project>`, `approve`,
   `reject <feedback>`, `start milestone <n>`, `status`, `stop` (A4), plus free
   text during planning (forwarded to the agent as answers).