Merge remote-tracking branch 'origin/master' into fix/subagent-depth-budget

# Conflicts:
#	docs/persistence-catalog.md

docs/architecture.md

@@ -55,9 +55,9 @@ Waterfall events behave like around-middleware: a listener delegates by calling
 
 ## Default Loop Lifecycle
 
-The shipped loop drains work from prompt through checkpoint. Every pause is a service call or event available to plugins.
+The shipped loop drains prompt-to-checkpoint work through plugin-visible services and events.
 
-A **session** is an append-only event log. A **turn** drains queued input until the model stops asking for tools and no plugin requests continuation. A **step** is one model request plus the tool executions caused by that response. In the flow below ([sequence companion](agent-lifecycle.md)), quoted names are durable session events and event names are extension points.
+A **session** is an append-only log. Each ordinary **turn** claims one queued `send()` item; injection claims none. A claimed `send()` successor awaits the preceding claimed ordinary turn's checkpoint but may share its `running` interval ([decision](../.agents/notes/implemented/simplification/2026-07-17-one-send-one-turn.md)). A turn ends when model and plugins stop it. A **step** is one model request plus tools. Below ([sequence companion](agent-lifecycle.md)), quotes mark durable events; other names are extension points.
 
 Startup resolves identity. No id mints `<config-id>-session-<uuid>`; `sessionId` resumes or creates; `resumeSessionId` requires history. Resume reconstructs durable session metadata before publication, so lineage, seed boundaries, and delegation depth survive restart. Active failures emit `agent-loop/config-start-failed(sessionId, error)`, so front doors reject work; teardown stays silent.
 
@@ -69,13 +69,13 @@ choose declarative identity and fresh/resume path
   -> enter session + agent -> session/created -> agent/created
   -> enable driving -> agent/session-start(source) -> start driver
 forever:
-  wait for queued messages
+  wait for a queued message
   emit agent/status(running)
   TURN:
     'turn/start'
-    each queued message -> agent/prompt-submit
+    claimed message -> agent/prompt-submit
       allowed prompt -> 'user/message' plus injected context
-    every prompt blocked -> 'turn/end'(rejected)
+      blocked prompt -> 'prompt/blocked' -> 'turn/end'(rejected)
     STEP loop:
       drain steering
       assemble system prompt and tool schemas