1 files changed, 86 insertions, 0 deletions
diff --git a/crates/fidget-spinner-cli/src/mcp/protocol.rs b/crates/fidget-spinner-cli/src/mcp/protocol.rs
new file mode 100644
index 0000000..1f24f37
--- /dev/null
+++ b/crates/fidget-spinner-cli/src/mcp/protocol.rs
@@ -0,0 +1,86 @@
+use std::path::PathBuf;
+
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+use crate::mcp::telemetry::ServerTelemetry;
+
+pub(crate) const PROTOCOL_VERSION: &str = "2025-11-25";
+pub(crate) const SERVER_NAME: &str = "fidget-spinner";
+pub(crate) const HOST_STATE_ENV: &str = "FIDGET_SPINNER_MCP_HOST_STATE";
+pub(crate) const FORCE_ROLLOUT_ENV: &str = "FIDGET_SPINNER_MCP_TEST_FORCE_ROLLOUT_KEY";
+pub(crate) const CRASH_ONCE_ENV: &str = "FIDGET_SPINNER_MCP_TEST_HOST_CRASH_ONCE_KEY";
+pub(crate) const TRANSIENT_ONCE_ENV: &str = "FIDGET_SPINNER_MCP_TEST_WORKER_TRANSIENT_ONCE_KEY";
+pub(crate) const TRANSIENT_ONCE_MARKER_ENV: &str =
+    "FIDGET_SPINNER_MCP_TEST_WORKER_TRANSIENT_ONCE_MARKER";
+
+#[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
+pub(crate) struct SessionSeed {
+    pub initialize_params: Option<Value>,
+    pub initialized: bool,
+}
+
+#[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
+pub(crate) struct HostStateSeed {
+    pub session: SessionSeed,
+    pub telemetry: ServerTelemetry,
+    pub next_request_id: u64,
+    pub binding: Option<ProjectBindingSeed>,
+    pub worker_generation: u64,
+    pub force_rollout_consumed: bool,
+    pub crash_once_consumed: bool,
+}
+
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub(crate) struct ProjectBindingSeed {
+    pub requested_path: PathBuf,
+    pub project_root: PathBuf,
+}
+
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Ord, PartialEq, PartialOrd, Serialize)]
+#[serde(transparent)]
+pub(crate) struct HostRequestId(pub u64);
+
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+#[serde(tag = "kind", rename_all = "snake_case")]
+pub(crate) enum WorkerRequest {
+    Execute {
+        id: HostRequestId,
+        operation: WorkerOperation,
+    },
+}
+
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+#[serde(tag = "kind", rename_all = "snake_case")]
+pub(crate) enum WorkerOperation {
+    CallTool { name: String, arguments: Value },
+    ReadResource { uri: String },
+}
+
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub(crate) struct WorkerResponse {
+    pub id: HostRequestId,
+    pub outcome: WorkerOutcome,
+}
+
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+#[serde(tag = "status", rename_all = "snake_case")]
+pub(crate) enum WorkerOutcome {
+    Success {
+        result: Value,
+    },
+    Fault {
+        fault: crate::mcp::fault::FaultRecord,
+    },
+}
+
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub(crate) struct BinaryFingerprint {
+    pub length_bytes: u64,
+    pub modified_unix_nanos: u128,
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct WorkerSpawnConfig {
+    pub executable: PathBuf,
+}