diff --git a/agent/agent_runtime_helpers.py b/agent/agent_runtime_helpers.py
index 7a9a0961a75..b98fe4b44e7 100644
--- a/agent/agent_runtime_helpers.py
+++ b/agent/agent_runtime_helpers.py
@@ -1869,6 +1869,77 @@ def copy_reasoning_content_for_api(agent, source_msg: dict, api_msg: dict) -> No
 
 
 
+def _iter_pool_sockets(client: Any):
+    """Yield raw sockets reachable from an OpenAI/httpx client pool.
+
+    httpcore 1.x stores the concrete HTTP11/HTTP2 connection under
+    ``conn._connection``; older versions exposed stream attributes directly
+    on the pool entry. Keep the traversal defensive because these are private
+    transport internals and vary across httpx/httpcore releases.
+    """
+    try:
+        http_client = getattr(client, "_client", None)
+        if http_client is None:
+            return
+        transport = getattr(http_client, "_transport", None)
+        if transport is None:
+            return
+        pool = getattr(transport, "_pool", None)
+        if pool is None:
+            return
+        connections = (
+            getattr(pool, "_connections", None)
+            or getattr(pool, "_pool", None)
+            or []
+        )
+    except Exception:
+        return
+
+    seen: set[int] = set()
+    for conn in list(connections):
+        candidates = [conn]
+        inner = getattr(conn, "_connection", None)
+        if inner is not None:
+            candidates.append(inner)
+        for candidate in candidates:
+            stream = (
+                getattr(candidate, "_network_stream", None)
+                or getattr(candidate, "_stream", None)
+            )
+            if stream is None:
+                continue
+            sock = getattr(stream, "_sock", None)
+            if sock is None:
+                get_extra_info = getattr(stream, "get_extra_info", None)
+                if callable(get_extra_info):
+                    try:
+                        sock = get_extra_info("socket")
+                    except Exception:
+                        sock = None
+            if sock is None:
+                wrapped = getattr(stream, "stream", None)
+                if wrapped is not None:
+                    sock = getattr(wrapped, "_sock", None)
+            if sock is None:
+                # anyio-backed streams expose the raw socket through
+                # SocketAttribute.raw_socket when available.
+                wrapped = getattr(stream, "_stream", None)
+                extra = getattr(wrapped, "extra", None)
+                if callable(extra):
+                    try:
+                        from anyio.abc import SocketAttribute
+                        sock = extra(SocketAttribute.raw_socket)
+                    except Exception:
+                        sock = None
+            if sock is None:
+                continue
+            marker = id(sock)
+            if marker in seen:
+                continue
+            seen.add(marker)
+            yield sock
+
+
 def cleanup_dead_connections(agent) -> bool:
     """Detect and clean up dead TCP connections on the primary client.
 
@@ -1882,36 +1953,8 @@ def cleanup_dead_connections(agent) -> bool:
     if client is None:
         return False
     try:
-        http_client = getattr(client, "_client", None)
-        if http_client is None:
-            return False
-        transport = getattr(http_client, "_transport", None)
-        if transport is None:
-            return False
-        pool = getattr(transport, "_pool", None)
-        if pool is None:
-            return False
-        connections = (
-            getattr(pool, "_connections", None)
-            or getattr(pool, "_pool", None)
-            or []
-        )
         dead_count = 0
-        for conn in list(connections):
-            # Check for connections that are idle but have closed sockets
-            stream = (
-                getattr(conn, "_network_stream", None)
-                or getattr(conn, "_stream", None)
-            )
-            if stream is None:
-                continue
-            sock = getattr(stream, "_sock", None)
-            if sock is None:
-                sock = getattr(stream, "stream", None)
-                if sock is not None:
-                    sock = getattr(sock, "_sock", None)
-            if sock is None:
-                continue
+        for sock in _iter_pool_sockets(client):
             # Probe socket health with a non-blocking recv peek
             import socket as _socket
             try:
@@ -2087,36 +2130,7 @@ def force_close_tcp_sockets(client: Any) -> int:
 
     closed = 0
     try:
-        http_client = getattr(client, "_client", None)
-        if http_client is None:
-            return 0
-        transport = getattr(http_client, "_transport", None)
-        if transport is None:
-            return 0
-        pool = getattr(transport, "_pool", None)
-        if pool is None:
-            return 0
-        # httpx uses httpcore connection pools; connections live in
-        # _connections (list) or _pool (list) depending on version.
-        connections = (
-            getattr(pool, "_connections", None)
-            or getattr(pool, "_pool", None)
-            or []
-        )
-        for conn in list(connections):
-            stream = (
-                getattr(conn, "_network_stream", None)
-                or getattr(conn, "_stream", None)
-            )
-            if stream is None:
-                continue
-            sock = getattr(stream, "_sock", None)
-            if sock is None:
-                sock = getattr(stream, "stream", None)
-                if sock is not None:
-                    sock = getattr(sock, "_sock", None)
-            if sock is None:
-                continue
+        for sock in _iter_pool_sockets(client):
             try:
                 sock.shutdown(_socket.SHUT_RDWR)
             except OSError:
@@ -2154,5 +2168,6 @@ __all__ = [
     "cleanup_dead_connections",
     "extract_api_error_context",
     "apply_pending_steer_to_tool_results",
+    "_iter_pool_sockets",
     "force_close_tcp_sockets",
 ]
diff --git a/agent/chat_completion_helpers.py b/agent/chat_completion_helpers.py
index 2e0caebcbe3..c68f2271f5b 100644
--- a/agent/chat_completion_helpers.py
+++ b/agent/chat_completion_helpers.py
@@ -92,17 +92,36 @@ def interruptible_api_call(agent, api_kwargs: dict):
     """
     result = {"response": None, "error": None}
     request_client_holder = {"client": None}
+    request_client_lock = threading.Lock()
+
+    def _set_request_client(client):
+        with request_client_lock:
+            request_client_holder["client"] = client
+        return client
+
+    def _take_request_client():
+        with request_client_lock:
+            client = request_client_holder.get("client")
+            request_client_holder["client"] = None
+            return client
+
+    def _close_request_client_once(reason: str) -> None:
+        request_client = _take_request_client()
+        if request_client is not None:
+            agent._close_request_openai_client(request_client, reason=reason)
 
     def _call():
         try:
             if agent.api_mode == "codex_responses":
-                request_client_holder["client"] = agent._create_request_openai_client(
-                    reason="codex_stream_request",
-                    api_kwargs=api_kwargs,
+                request_client = _set_request_client(
+                    agent._create_request_openai_client(
+                        reason="codex_stream_request",
+                        api_kwargs=api_kwargs,
+                    )
                 )
                 result["response"] = agent._run_codex_stream(
                     api_kwargs,
-                    client=request_client_holder["client"],
+                    client=request_client,
                     on_first_delta=getattr(agent, "_codex_on_first_delta", None),
                 )
             elif agent.api_mode == "anthropic_messages":
@@ -131,17 +150,17 @@ def interruptible_api_call(agent, api_kwargs: dict):
                     raise
                 result["response"] = normalize_converse_response(raw_response)
             else:
-                request_client_holder["client"] = agent._create_request_openai_client(
-                    reason="chat_completion_request",
-                    api_kwargs=api_kwargs,
+                request_client = _set_request_client(
+                    agent._create_request_openai_client(
+                        reason="chat_completion_request",
+                        api_kwargs=api_kwargs,
+                    )
                 )
-                result["response"] = request_client_holder["client"].chat.completions.create(**api_kwargs)
+                result["response"] = request_client.chat.completions.create(**api_kwargs)
         except Exception as e:
             result["error"] = e
         finally:
-            request_client = request_client_holder.get("client")
-            if request_client is not None:
-                agent._close_request_openai_client(request_client, reason="request_complete")
+            _close_request_client_once("request_complete")
 
     # ── Stale-call timeout (mirrors streaming stale detector) ────────
     # Non-streaming calls return nothing until the full response is
@@ -192,9 +211,7 @@ def interruptible_api_call(agent, api_kwargs: dict):
                     agent._anthropic_client.close()
                     agent._rebuild_anthropic_client()
                 else:
-                    rc = request_client_holder.get("client")
-                    if rc is not None:
-                        agent._close_request_openai_client(rc, reason="stale_call_kill")
+                    _close_request_client_once("stale_call_kill")
             except Exception:
                 pass
             agent._touch_activity(
@@ -218,9 +235,7 @@ def interruptible_api_call(agent, api_kwargs: dict):
                     agent._anthropic_client.close()
                     agent._rebuild_anthropic_client()
                 else:
-                    request_client = request_client_holder.get("client")
-                    if request_client is not None:
-                        agent._close_request_openai_client(request_client, reason="interrupt_abort")
+                    _close_request_client_once("interrupt_abort")
             except Exception:
                 pass
             raise InterruptedError("Agent interrupted during API call")
@@ -1257,6 +1272,24 @@ def interruptible_streaming_api_call(agent, api_kwargs: dict, *, on_first_delta=
 
     result = {"response": None, "error": None, "partial_tool_names": []}
     request_client_holder = {"client": None, "diag": None}
+    request_client_lock = threading.Lock()
+
+    def _set_request_client(client):
+        with request_client_lock:
+            request_client_holder["client"] = client
+        return client
+
+    def _take_request_client():
+        with request_client_lock:
+            client = request_client_holder.get("client")
+            request_client_holder["client"] = None
+            return client
+
+    def _close_request_client_once(reason: str) -> None:
+        request_client = _take_request_client()
+        if request_client is not None:
+            agent._close_request_openai_client(request_client, reason=reason)
+
     first_delta_fired = {"done": False}
     deltas_were_sent = {"yes": False}  # Track if any deltas were fired (for fallback)
     # Wall-clock timestamp of the last real streaming chunk.  The outer
@@ -1313,9 +1346,11 @@ def interruptible_streaming_api_call(agent, api_kwargs: dict, *, on_first_delta=
                 pool=_conn_cap,
             ),
         }
-        request_client_holder["client"] = agent._create_request_openai_client(
-            reason="chat_completion_stream_request",
-            api_kwargs=stream_kwargs,
+        request_client = _set_request_client(
+            agent._create_request_openai_client(
+                reason="chat_completion_stream_request",
+                api_kwargs=stream_kwargs,
+            )
         )
         # Reset stale-stream timer so the detector measures from this
         # attempt's start, not a previous attempt's last chunk.
@@ -1326,7 +1361,7 @@ def interruptible_streaming_api_call(agent, api_kwargs: dict, *, on_first_delta=
         # ``request_client_holder["diag"]`` for closure access.
         _diag = agent._stream_diag_init()
         request_client_holder["diag"] = _diag
-        stream = request_client_holder["client"].chat.completions.create(**stream_kwargs)
+        stream = request_client.chat.completions.create(**stream_kwargs)
 
         # Capture rate limit headers from the initial HTTP response.
         # The OpenAI SDK Stream object exposes the underlying httpx
@@ -1765,12 +1800,7 @@ def interruptible_streaming_api_call(agent, api_kwargs: dict, *, on_first_delta=
                             mid_tool_call=True,
                             diag=request_client_holder.get("diag"),
                         )
-                        stale = request_client_holder.get("client")
-                        if stale is not None:
-                            agent._close_request_openai_client(
-                                stale, reason="stream_mid_tool_retry_cleanup"
-                            )
-                            request_client_holder["client"] = None
+                        _close_request_client_once("stream_mid_tool_retry_cleanup")
                         try:
                             agent._replace_primary_openai_client(
                                 reason="stream_mid_tool_retry_pool_cleanup"
@@ -1821,12 +1851,7 @@ def interruptible_streaming_api_call(agent, api_kwargs: dict, *, on_first_delta=
                                 diag=request_client_holder.get("diag"),
                             )
                             # Close the stale request client before retry
-                            stale = request_client_holder.get("client")
-                            if stale is not None:
-                                agent._close_request_openai_client(
-                                    stale, reason="stream_retry_cleanup"
-                                )
-                                request_client_holder["client"] = None
+                            _close_request_client_once("stream_retry_cleanup")
                             # Also rebuild the primary client to purge
                             # any dead connections from the pool.
                             try:
@@ -1894,9 +1919,7 @@ def interruptible_streaming_api_call(agent, api_kwargs: dict, *, on_first_delta=
             result["error"] = e
             return
         finally:
-            request_client = request_client_holder.get("client")
-            if request_client is not None:
-                agent._close_request_openai_client(request_client, reason="stream_request_complete")
+            _close_request_client_once("stream_request_complete")
 
     # Provider-configured stale timeout takes priority over env default.
     _cfg_stale = get_provider_stale_timeout(agent.provider, agent.model)
@@ -1966,9 +1989,7 @@ def interruptible_streaming_api_call(agent, api_kwargs: dict, *, on_first_delta=
                 f"Reconnecting..."
             )
             try:
-                rc = request_client_holder.get("client")
-                if rc is not None:
-                    agent._close_request_openai_client(rc, reason="stale_stream_kill")
+                _close_request_client_once("stale_stream_kill")
             except Exception:
                 pass
             # Rebuild the primary client too — its connection pool
@@ -1990,9 +2011,7 @@ def interruptible_streaming_api_call(agent, api_kwargs: dict, *, on_first_delta=
                     agent._anthropic_client.close()
                     agent._rebuild_anthropic_client()
                 else:
-                    request_client = request_client_holder.get("client")
-                    if request_client is not None:
-                        agent._close_request_openai_client(request_client, reason="stream_interrupt_abort")
+                    _close_request_client_once("stream_interrupt_abort")
             except Exception:
                 pass
             raise InterruptedError("Agent interrupted during streaming API call")
diff --git a/hermes_cli/kanban_db.py b/hermes_cli/kanban_db.py
index d557354238c..7a30b70987f 100644
--- a/hermes_cli/kanban_db.py
+++ b/hermes_cli/kanban_db.py
@@ -951,6 +951,58 @@ CREATE INDEX IF NOT EXISTS idx_notify_task           ON kanban_notify_subs(task_
 
 _INITIALIZED_PATHS: set[str] = set()
 _INIT_LOCK = threading.RLock()
+_SQLITE_HEADER = b"SQLite format 3\x00"
+
+
+def _looks_like_tls_record_at(data: bytes, offset: int) -> bool:
+    """Return True for a TLS record header at ``data[offset:]``."""
+    if len(data) < offset + 5:
+        return False
+    content_type = data[offset]
+    major = data[offset + 1]
+    minor = data[offset + 2]
+    length = int.from_bytes(data[offset + 3:offset + 5], "big")
+    return (
+        content_type in {0x14, 0x15, 0x16, 0x17}
+        and major == 0x03
+        and minor in {0x00, 0x01, 0x02, 0x03, 0x04}
+        and 0 < length <= 18432
+    )
+
+
+def _validate_sqlite_header(path: Path) -> None:
+    """Fail early with an actionable error for non-SQLite Kanban DB files.
+
+    ``sqlite3.connect()`` creates missing and zero-byte files, so those are
+    allowed. Existing non-empty files must have the SQLite header before we
+    hand them to SQLite/WAL setup. This keeps corrupted page-0 failures from
+    being collapsed into a generic PRAGMA error and lets the gateway's corrupt
+    board handling identify the board by fingerprint.
+    """
+    try:
+        stat = path.stat()
+    except FileNotFoundError:
+        return
+    except OSError:
+        return
+    if stat.st_size == 0:
+        return
+    try:
+        with path.open("rb") as handle:
+            head = handle.read(64)
+    except OSError:
+        return
+    if head.startswith(_SQLITE_HEADER):
+        return
+    signature = ""
+    if head.startswith(b"SQLit") and _looks_like_tls_record_at(head, 5):
+        signature = " (TLS record header detected at byte offset 5)"
+    elif _looks_like_tls_record_at(head, 0):
+        signature = " (TLS record header detected at byte offset 0)"
+    raise sqlite3.DatabaseError(
+        "file is not a database: invalid SQLite header for "
+        f"{path}{signature}; first_32={head[:32].hex(' ')}"
+    )
 
 
 def connect(
@@ -981,6 +1033,7 @@ def connect(
     else:
         path = kanban_db_path(board=board)
     path.parent.mkdir(parents=True, exist_ok=True)
+    _validate_sqlite_header(path)
     resolved = str(path.resolve())
     conn = sqlite3.connect(str(path), isolation_level=None, timeout=30)
     try:
diff --git a/tests/hermes_cli/test_kanban_db.py b/tests/hermes_cli/test_kanban_db.py
index 64ed630db1c..435ef41001a 100644
--- a/tests/hermes_cli/test_kanban_db.py
+++ b/tests/hermes_cli/test_kanban_db.py
@@ -48,6 +48,27 @@ def test_init_creates_expected_tables(kanban_home):
     assert {"tasks", "task_links", "task_comments", "task_events"} <= names
 
 
+def test_connect_rejects_tls_record_in_sqlite_header(tmp_path, monkeypatch):
+    """Kanban should classify TLS-looking page-0 clobbers before WAL setup."""
+    home = tmp_path / ".hermes"
+    home.mkdir()
+    monkeypatch.setenv("HERMES_HOME", str(home))
+    monkeypatch.delenv("HERMES_KANBAN_DB", raising=False)
+    monkeypatch.delenv("HERMES_KANBAN_HOME", raising=False)
+    monkeypatch.setattr(Path, "home", lambda: tmp_path)
+
+    corrupt = home / "kanban.db"
+    corrupt.write_bytes(b"SQLit" + bytes.fromhex("17 03 03 00 13") + b"x" * 32)
+
+    with pytest.raises(sqlite3.DatabaseError) as exc_info:
+        kb.connect(board="default")
+
+    msg = str(exc_info.value)
+    assert "file is not a database" in msg
+    assert "TLS record header detected at byte offset 5" in msg
+    assert "53 51 4c 69 74 17 03 03 00 13" in msg
+
+
 def test_connect_migrates_legacy_db_before_optional_column_indexes(tmp_path):
     """Legacy DBs missing additive indexed columns must migrate cleanly.
 
diff --git a/tests/run_agent/test_create_openai_client_reuse.py b/tests/run_agent/test_create_openai_client_reuse.py
index 0eac567ae6c..13d95a46634 100644
--- a/tests/run_agent/test_create_openai_client_reuse.py
+++ b/tests/run_agent/test_create_openai_client_reuse.py
@@ -16,6 +16,7 @@ with ``APIConnectionError('Connection error.')`` whose cause was
 That is the exact scenario this test reproduces at object level without a
 network, so it runs in CI on every PR.
 """
+from types import SimpleNamespace
 from unittest.mock import MagicMock, patch
 
 from run_agent import AIAgent
@@ -186,3 +187,32 @@ def test_replace_primary_openai_client_survives_repeated_rebuilds():
         "Some _create_openai_client calls returned the same object across "
         "a teardown — rebuild is not producing fresh clients"
     )
+
+
+def test_force_close_tcp_sockets_descends_httpcore_1_connection_wrapper():
+    """httpcore 1.x stores the real stream below conn._connection."""
+    from agent.agent_runtime_helpers import force_close_tcp_sockets
+
+    class FakeSocket:
+        def __init__(self):
+            self.shutdown_calls = 0
+            self.close_calls = 0
+
+        def shutdown(self, _how):
+            self.shutdown_calls += 1
+
+        def close(self):
+            self.close_calls += 1
+
+    sock = FakeSocket()
+    stream = SimpleNamespace(_sock=sock)
+    http11 = SimpleNamespace(_network_stream=stream)
+    pool_entry = SimpleNamespace(_connection=http11)
+    pool = SimpleNamespace(_connections=[pool_entry])
+    transport = SimpleNamespace(_pool=pool)
+    http_client = SimpleNamespace(_transport=transport)
+    openai_client = SimpleNamespace(_client=http_client)
+
+    assert force_close_tcp_sockets(openai_client) == 1
+    assert sock.shutdown_calls == 1
+    assert sock.close_calls == 1
diff --git a/tests/run_agent/test_openai_client_lifecycle.py b/tests/run_agent/test_openai_client_lifecycle.py
index 72d92fd15e1..35a8ec7a084 100644
--- a/tests/run_agent/test_openai_client_lifecycle.py
+++ b/tests/run_agent/test_openai_client_lifecycle.py
@@ -1,5 +1,6 @@
 import sys
 import threading
+import time
 import types
 from types import SimpleNamespace
 
@@ -64,6 +65,7 @@ def _build_agent(shared_client=None):
     agent.stream_delta_callback = None
     agent._stream_callback = None
     agent.reasoning_callback = None
+    agent.status_callback = None
     return agent
 
 
@@ -93,6 +95,24 @@ def test_retry_after_api_connection_error_recreates_request_client(monkeypatch):
     assert second_request.close_calls >= 1
 
 
+def test_stale_non_stream_close_is_single_owner(monkeypatch):
+    def slow_responder(**kwargs):
+        time.sleep(0.1)
+        raise _connection_error()
+
+    request_client = FakeRequestClient(slow_responder)
+    factory = OpenAIFactory([request_client])
+    monkeypatch.setattr(run_agent, "OpenAI", factory)
+
+    agent = _build_agent()
+    agent._compute_non_stream_stale_timeout = lambda _messages: 0.01
+
+    with pytest.raises(APIConnectionError):
+        agent._interruptible_api_call({"model": agent.model, "messages": []})
+
+    assert request_client.close_calls == 1
+
+
 def test_closed_shared_client_is_recreated_before_request(monkeypatch):
     stale_shared = FakeSharedClient(lambda **kwargs: (_ for _ in ()).throw(AssertionError("stale shared client used")))
     stale_shared._client.is_closed = True