diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 0fc1453..14fcfc7 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -103,7 +103,7 @@ repos:
           - requests
           - gatelock @ git+https://github.com/kuhyx/utils@gatelock-v0.4.0#subdirectory=gatelock
           - crdt-sync @ git+https://github.com/kuhyx/utils@crdt-sync-v0.1.0#subdirectory=crdt-sync
-          - mcp
+          - mcp>=1.9,<2
           - pydantic
         # Test suites intentionally use patterns (protected-access, magic-value
         # comparisons) that don't belong in the source-code 10/10 gate.
diff --git a/pyproject.toml b/pyproject.toml
index e4d7e2f..b6768f9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,7 +15,7 @@ dependencies = [
 # so the systemd/CLI system-python path stays dependency-light and never has
 # to import the MCP SDK.
 [project.optional-dependencies]
-mcp = ["mcp>=1.9"]
+mcp = ["mcp>=1.9,<2"]
 
 # Without this, setuptools' flat-layout auto-discovery treats the Flutter
 # app/ directory as a second top-level package and refuses to build.
diff --git a/requirements.txt b/requirements.txt
index 99e388d..6d8ecc9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,7 +5,7 @@ codespell>=2.2.0
 coverage>=7.4.0
 crdt-sync @ git+https://github.com/kuhyx/utils@crdt-sync-v0.1.0#subdirectory=crdt-sync
 gatelock @ git+https://github.com/kuhyx/utils@gatelock-v0.4.0#subdirectory=gatelock
-mcp>=1.9
+mcp>=1.9,<2
 mypy>=1.8.0
 pre-commit>=3.6.0
 pydantic>=2