diff --git a/src/gflow_cli/mcp/server.py b/src/gflow_cli/mcp/server.py
index 218aab4cb..7a4cecdb5 100644
--- a/src/gflow_cli/mcp/server.py
+++ b/src/gflow_cli/mcp/server.py
@@ -126,6 +126,27 @@ def _configure_utf8_pipes() -> None:
 _SPEND_TOOLS = ("gflow_generate_image", "gflow_generate_video")
 
 
+def _apply_mcp_lease_wait_default() -> None:
+    """Make profile contention wait instead of hard-failing (reliability).
+
+    The CLI's fail-fast default (``GFLOW_CLI_LEASE_WAIT_SECONDS=0``, see
+    ``config.py``) is correct for a one-shot terminal command: a human is
+    watching and can just retry. An MCP client has no such human in the
+    loop — two tool calls landing close together on the same profile (a
+    retry after a slow response, or two agents sharing a profile) would
+    otherwise hard-fail with ``ProfileLockedError`` instead of the caller's
+    request simply running after the one already in flight. `setdefault`
+    only takes effect for a caller who has not already set the var, and
+    `get_settings()` is process-cached (`@lru_cache`), so this MUST run
+    before anything in this process calls it — hence first line of every
+    `run_*` entry point, before `_register_surfaces()`.
+
+    180s covers a typical single image/video generation with headroom
+    without hanging an MCP client indefinitely on a genuinely stuck holder.
+    """
+    os.environ.setdefault("GFLOW_CLI_LEASE_WAIT_SECONDS", "180")
+
+
 def no_spend_active() -> bool:
     """True when no-spend mode is requested (#496).
 
@@ -304,6 +325,7 @@ async def run_stdio() -> None:
     import anyio
     from mcp.server.stdio import stdio_server
 
+    _apply_mcp_lease_wait_default()
     _configure_utf8_pipes()
 
     # Capture the REAL stdout for the JSON-RPC channel BEFORE redirecting
@@ -350,6 +372,7 @@ async def run_http(host: str = "127.0.0.1", port: int = 8000) -> None:
         host: Bind address. Defaults to localhost-only for security.
         port: Port number. Defaults to 8000.
     """
+    _apply_mcp_lease_wait_default()
     _configure_utf8_pipes()
 
     token = _daemon_token()
@@ -385,6 +408,7 @@ async def run_sse(host: str = "127.0.0.1", port: int = 8000) -> None:
         host: Bind address. Defaults to localhost-only for security.
         port: Port number. Defaults to 8000.
     """
+    _apply_mcp_lease_wait_default()
     _configure_utf8_pipes()
 
     token = _daemon_token()
diff --git a/tests/mcp/test_server.py b/tests/mcp/test_server.py
index a95d18bb6..36e750399 100644
--- a/tests/mcp/test_server.py
+++ b/tests/mcp/test_server.py
@@ -11,6 +11,7 @@
 from __future__ import annotations
 
 import asyncio
+import os
 from typing import Any
 from unittest.mock import patch
 
@@ -567,6 +568,7 @@ async def fake_stdio_server(stdout=None):
 
         with (
             patch("gflow_cli.mcp.server.server") as mock_server,
+            patch("gflow_cli.mcp.server._apply_mcp_lease_wait_default"),
             patch("gflow_cli.mcp.server._configure_utf8_pipes"),
             patch("gflow_cli.mcp.server._redirect_stdout_to_stderr"),
             patch("gflow_cli.mcp.server.sys.stdout", MagicMock()),
@@ -600,6 +602,7 @@ async def test_run_http_starts_streamable_http_on_mcp_path(self) -> None:
 
         with (
             patch("gflow_cli.mcp.server.server") as mock_server,
+            patch("gflow_cli.mcp.server._apply_mcp_lease_wait_default"),
             patch("gflow_cli.mcp.server._configure_utf8_pipes"),
             patch("gflow_cli.mcp.server._serve", new_callable=AsyncMock) as mock_serve,
         ):
@@ -629,6 +632,7 @@ async def test_run_sse_configures_and_starts(self) -> None:
 
         with (
             patch("gflow_cli.mcp.server.server") as mock_server,
+            patch("gflow_cli.mcp.server._apply_mcp_lease_wait_default"),
             patch("gflow_cli.mcp.server._configure_utf8_pipes"),
             patch("gflow_cli.mcp.server._serve", new_callable=AsyncMock) as mock_serve,
         ):
@@ -639,6 +643,26 @@ async def test_run_sse_configures_and_starts(self) -> None:
             mock_serve.assert_awaited_once_with(app, host="127.0.0.1", port=9999)
 
 
+class TestMcpLeaseWaitDefault:
+    """The MCP server should wait out profile contention instead of the CLI's
+    fail-fast default — no human is watching an MCP call to just retry it."""
+
+    def test_sets_default_when_unset(self, monkeypatch: pytest.MonkeyPatch) -> None:
+        from gflow_cli.mcp.server import _apply_mcp_lease_wait_default
+
+        monkeypatch.delenv("GFLOW_CLI_LEASE_WAIT_SECONDS", raising=False)
+        _apply_mcp_lease_wait_default()
+        assert os.environ["GFLOW_CLI_LEASE_WAIT_SECONDS"] == "180"
+
+    def test_never_overrides_an_explicit_value(self, monkeypatch: pytest.MonkeyPatch) -> None:
+        """A user/operator override (including an explicit fail-fast `0`) wins."""
+        from gflow_cli.mcp.server import _apply_mcp_lease_wait_default
+
+        monkeypatch.setenv("GFLOW_CLI_LEASE_WAIT_SECONDS", "0")
+        _apply_mcp_lease_wait_default()
+        assert os.environ["GFLOW_CLI_LEASE_WAIT_SECONDS"] == "0"
+
+
 def test_mcp_retryable_matches_cli() -> None:
     """§6.5 (S24): the MCP error envelope's retryable flag must derive from the
     same shared classification the CLI JSON surface uses — no drift lists."""