diff --git a/backend/apps/agents/core/models.py b/backend/apps/agents/core/models.py
index 06e0015b..612b21bb 100644
--- a/backend/apps/agents/core/models.py
+++ b/backend/apps/agents/core/models.py
@@ -209,6 +209,9 @@ class AgentSession(BaseModel):
     # first? Per-turn counters die with the turn, so a block envelope carried nothing.
     cli_compactions: int = 0
     midturn_breaks: int = 0
+    # The third context event, and the one that actually fires: a proactive prune reclaimed 40K on a
+    # real session while BOTH counters above read 0, so the fleet still could not see it (ENG-418).
+    proactive_prunes: int = 0
     # Aux-LLM distilled summary of the turns dropped by compaction, cached against the cutoff id it was built for; keeps the gist of old history on a rebuild instead of a hard drop.
     compacted_summary: Optional[str] = None
     compacted_summary_through: Optional[str] = None
diff --git a/backend/apps/agents/manager/run/handle_run_error.py b/backend/apps/agents/manager/run/handle_run_error.py
index 17cc44c2..f99d8280 100644
--- a/backend/apps/agents/manager/run/handle_run_error.py
+++ b/backend/apps/agents/manager/run/handle_run_error.py
@@ -108,6 +108,7 @@ def p_report_model_error(subkind: str, session_id: str, session: AgentSession, t
             # many times the CLI compacted this chat, and how many times we broke the turn first.
             "cli_compactions": int(getattr(session, "cli_compactions", 0) or 0),
             "midturn_breaks": int(getattr(session, "midturn_breaks", 0) or 0),
+            "proactive_prunes": int(getattr(session, "proactive_prunes", 0) or 0),
             "history_prefix_sent": session.history_prefix_sent,
             "delegated": p_used_delegation(session),
         })
diff --git a/backend/apps/agents/manager/session/history_compaction.py b/backend/apps/agents/manager/session/history_compaction.py
index 25d65be9..9b3a9ec3 100644
--- a/backend/apps/agents/manager/session/history_compaction.py
+++ b/backend/apps/agents/manager/session/history_compaction.py
@@ -212,9 +212,16 @@ def build_history_prefix(messages, cutoff_msg_id: Optional[str] = None) -> str:
     if not lines:
         return ""
     # Framing lifted from hermes-agent's compaction handoff (context_compressor.py, MIT): reference only, never active instructions, the message after it is the single source of truth, and an explicit end marker so a weak model cannot read the last line as fresh input.
+    # Say it is PARTIAL when it is. Measured 2026-08-29 on the packaged build: after a proactive
+    # prune the model was asked what the user's FIRST message had been and confidently quoted a much
+    # later one, because nothing in the recap distinguishes "this is the start of the conversation"
+    # from "this is what survived". A recap that hides its own gap turns lost context into a
+    # confident wrong answer, which is worse than the loss.
+    p_partial = " Earlier turns have been dropped to save space, so this does NOT begin at the start of the conversation; if asked about something not in it, say so rather than guessing." if cutoff_msg_id else ""
     p_recap_frame = ("Recap of YOUR OWN earlier turns in this same conversation (what was asked and which tools "
-                     "you ran), kept locally by the OpenSwarm app so you can continue where you left off. "
-                     "Reference only: do not answer or redo anything in it; respond to the message that follows.")
+                     "you ran), kept locally by the OpenSwarm app so you can continue where you left off."
+                     + p_partial +
+                     " Reference only: do not answer or redo anything in it; respond to the message that follows.")
     return (f"{SESSION_RECAP_OPEN}\n{PLATFORM_NOTE_PREAMBLE}\n{p_recap_frame}\n" + "\n".join(lines)
             + f"\n--- end of recap; respond to the message below, not the recap above ---\n{SESSION_RECAP_CLOSE}")
 
diff --git a/backend/apps/agents/manager/session/proactive_prune.py b/backend/apps/agents/manager/session/proactive_prune.py
index 58750ad2..8b896197 100644
--- a/backend/apps/agents/manager/session/proactive_prune.py
+++ b/backend/apps/agents/manager/session/proactive_prune.py
@@ -128,6 +128,7 @@ def arm_proactive_prune(session: AgentSession) -> None:
     """Commit the prune: mark history aged and force the rebuild that actually applies it."""
     from backend.apps.agents.manager.context_budget import maybe_compact
     maybe_compact(session, force=True)
+    session.proactive_prunes += 1
     session.needs_fresh_session = True
     session.proactive_prune_rearm_tokens = (
         estimate_aged_rebuild_tokens(session) + REARM_GROWTH_TOKENS
diff --git a/backend/tests/test_overcorrection_audit.py b/backend/tests/test_overcorrection_audit.py
index d57de450..797ac2aa 100644
--- a/backend/tests/test_overcorrection_audit.py
+++ b/backend/tests/test_overcorrection_audit.py
@@ -224,3 +224,80 @@ def test_a_terms_summary_is_not_mistaken_for_the_filter_refusing():
     ):
         assert neutralize_provider_refusal(innocent) == innocent
         assert classify_provider_error(innocent) is None
+
+
+# ------------------------------------------------- the mid-turn valve's growth rule (ENG-418)
+
+def test_a_turn_that_starts_high_and_sits_still_is_still_left_alone(monkeypatch):
+    """Growth made more turns breakable, and every break costs a transcript REBUILD -- the frequency
+    ENG-382 exists to reduce. The innocent case is a rebuild that failed to shrink: it starts high
+    and does not grow, and it must RUN rather than rebuild forever."""
+    from backend.apps.agents.manager.context_budget import maybe_break_midturn
+    from backend.apps.agents.manager.streaming.state import TurnState
+    s = AgentSession(name="t", model="opus-5"); s.context_window = 1_000_000
+    t = TurnState()
+    assert maybe_break_midturn(s, t, {"input_tokens": 500_000}) is False
+    assert maybe_break_midturn(s, t, {"input_tokens": 505_000}) is False, "5K is not material growth"
+    assert s.midturn_breaks == 0
+
+
+def test_a_grown_turn_breaks_at_most_once_so_rebuilds_cannot_multiply(monkeypatch):
+    from backend.apps.agents.manager.context_budget import maybe_break_midturn
+    from backend.apps.agents.manager.streaming.state import TurnState
+    s = AgentSession(name="t", model="opus-5"); s.context_window = 1_000_000
+    t = TurnState()
+    maybe_break_midturn(s, t, {"input_tokens": 100_000})
+    assert maybe_break_midturn(s, t, {"input_tokens": 400_000}) is True
+    for n in (500_000, 600_000, 900_000):
+        assert maybe_break_midturn(s, t, {"input_tokens": n}) is False
+    assert s.midturn_breaks == 1
+
+
+# --------------------------------------------------- Close vs Stop on a workflow card (ENG-421)
+
+def test_a_workflow_run_that_ended_on_its_own_still_despawns():
+    """The card is kept for a HUMAN stop. The innocent case is the nightly workflow that ends by
+    itself: keeping its card would leave litter on the canvas every single night, which is the leak
+    the original rule was written to prevent."""
+    a = "frontend/src/shared/state/isUserLaunchedSession.ts"
+    src = open(a, encoding="utf-8").read()
+    assert "if (LIVE_STATUSES.has" in src and "ended_by_user" in src
+    assert "!session.dismissed_by_user" in src, "Close must still be able to dismiss"
+    assert "!session.closed_at" not in src, \
+        "closed_at is stamped by the executor on every run; using it made the fix dead code"
+
+
+def test_the_dismissal_flag_is_at_the_close_door_not_in_the_shared_helper():
+    """agent_manager.close_session is called by the workflow executor for bookkeeping. A flag there
+    would mark every finished run as user-dismissed and delete the stopped-run cards again."""
+    helper = open("backend/apps/agents/manager/SessionControl.py", encoding="utf-8").read()
+    assert "dismissed_by_user" not in helper
+
+
+# ------------------------------------------------------ the PTC fan-out width cap (ENG-417)
+
+def test_one_scripts_fan_out_cannot_starve_the_rest_of_the_chat():
+    """The cap is module-global on purpose: two scripts in one sidecar SHARE the width rather than
+    each taking a full one. The innocent case is the chat's other builtin tools, which ride the same
+    process and must still get scheduled while a 25-call batch runs."""
+    from backend.apps.agents import ptc_mcp_server as ptc
+    src = open("backend/apps/agents/ptc_mcp_server.py", encoding="utf-8").read()
+    assert "P_FANOUT_SLOTS = threading.Semaphore(SCRIPT_FANOUT_WIDTH)" in src
+    i = src.index("def p_dispatch_batch")
+    body = src[i:src.index("def p_elide", i)]
+    assert "P_FANOUT_SLOTS.acquire(timeout=" in body, "an unbounded acquire can lose a slot forever"
+    assert "finally:" in body and "P_FANOUT_SLOTS.release()" in body
+    assert ptc.SCRIPT_FANOUT_WIDTH <= 8
+
+
+# ------------------------------------------------- the canvas wheel owner (ENG-420)
+
+def test_a_gesture_that_starts_on_a_panel_still_belongs_to_the_panel():
+    """Canvas ownership was added so a pan is not swallowed mid-drift. The innocent case is the
+    original rule it must not break: a scroll that starts inside Settings has to stay there past the
+    panel's end, or reaching the bottom of a list drags the whole world."""
+    src = open("frontend/src/app/pages/Dashboard/hooks/interaction/wheelGestureOwner.ts",
+               encoding="utf-8").read()
+    assert "owner === CANVAS_OWNER" in src
+    assert "owner.contains(target" in src, "an element owner must still hold its own gesture"
+    assert "isZoom" in src, "zoom must stay reachable on every surface"
diff --git a/backend/tests/test_recap_admits_its_gap.py b/backend/tests/test_recap_admits_its_gap.py
new file mode 100644
index 00000000..58f9bff0
--- /dev/null
+++ b/backend/tests/test_recap_admits_its_gap.py
@@ -0,0 +1,54 @@
+"""A recap that hides its own gap turns lost context into a confident wrong answer.
+
+Found on the packaged build 2026-08-29, simulating the heaviest real install's shape (123 tool calls,
+132K input, serial read->run->read work). A proactive prune reclaimed ~40K, which is by design. Then
+the chat was asked what the user's FIRST message had been, and it quoted a much later one as fact
+instead of saying it did not know. Nothing in the recap distinguishes "this is the start of the
+conversation" from "this is what survived the prune", so the model has no way to tell.
+
+Row 5 on the ladder (a lying status), reached from row 1 (context silently gone). The loss itself is
+the intended trade; presenting the remainder as the whole is not."""
+
+from backend.apps.agents.core.models import AgentSession, Message
+from backend.apps.agents.manager.session.history_compaction import build_history_prefix
+
+
+def p_msgs():
+    return [
+        Message(role="user", content="Work in /tmp/osw-heavy, there are 14 modules", branch_id="main"),
+        Message(role="tool_call", content={"tool": "Read", "input": {"file": "mod_01.py"}}, branch_id="main"),
+        Message(role="tool_result", content={"tool_name": "Read", "text": "ok"}, branch_id="main"),
+        Message(role="user", content="Now re-read them all", branch_id="main"),
+        Message(role="tool_call", content={"tool": "Read", "input": {"file": "mod_02.py"}}, branch_id="main"),
+        Message(role="tool_result", content={"tool_name": "Read", "text": "ok"}, branch_id="main"),
+        Message(role="user", content="And once more", branch_id="main"),
+    ]
+
+
+def test_a_pruned_recap_says_it_does_not_start_at_the_beginning():
+    msgs = p_msgs()
+    out = build_history_prefix(msgs, cutoff_msg_id=msgs[2].id)
+    low = out.lower()
+    assert "dropped" in low, "the recap must admit earlier turns are gone"
+    assert "does not begin at the start" in low or "not begin at the start" in low
+    assert "say so rather than guessing" in low, "and tell it what to do instead of inventing one"
+
+
+def test_an_UNPRUNED_recap_makes_no_such_claim():
+    """The innocent case: a full recap really does start at the beginning, and telling the model
+    otherwise would make it refuse to answer things it genuinely has."""
+    out = build_history_prefix(p_msgs(), cutoff_msg_id=None)
+    assert "dropped" not in out.lower()
+    assert "The user asked:" in out, "a full recap still carries the asks"
+
+
+def test_the_prune_is_counted_where_the_fleet_can_see_it():
+    """ENG-418 added counters for the CLI's compactions and our mid-turn breaks. On a real heavy
+    session BOTH read 0 while a proactive prune reclaimed ~40K, so the fleet still could not answer
+    'how often does a chat lose history'."""
+    s = AgentSession(name="t", model="opus-5")
+    assert s.proactive_prunes == 0
+    src = open("backend/apps/agents/manager/session/proactive_prune.py", encoding="utf-8").read()
+    assert "session.proactive_prunes += 1" in src
+    env = open("backend/apps/agents/manager/run/handle_run_error.py", encoding="utf-8").read()
+    assert '"proactive_prunes"' in env, "counted but never sent is the same blind spot"