diff --git a/server/src/cursor/tools/dispatch/mod.rs b/server/src/cursor/tools/dispatch/mod.rs
index eb4ea88..53ce5c1 100644
--- a/server/src/cursor/tools/dispatch/mod.rs
+++ b/server/src/cursor/tools/dispatch/mod.rs
@@ -51,6 +51,9 @@ pub(super) async fn start(
         return local::subagents_disabled(call);
     }
 
+    let normalized_call = normalize_block_until_ms(call)?;
+    let call = normalized_call.as_ref().unwrap_or(call);
+
     match normalized(&call.name).as_str() {
         "shell" | "read" | "delete" | "grep" | "glob" | "readlints" | "task" | "callmcptool"
         | "fetchmcpresource" | "getmcptools" => exec::start(runtime, call, context).await,
@@ -64,6 +67,55 @@ pub(super) async fn start(
     }
 }
 
+fn normalize_block_until_ms(call: &ToolCall) -> Result<Option<ToolCall>> {
+    if !matches!(normalized(&call.name).as_str(), "shell" | "awaitshell") {
+        return Ok(None);
+    }
+    let Some(value) = call.arguments.get("block_until_ms") else {
+        return Ok(None);
+    };
+
+    let integer = if let Some(value) = value.as_i64() {
+        value
+    } else {
+        let value = value.as_f64().ok_or_else(|| {
+            Error::Protocol(format!("{} block_until_ms must be an integer", call.name))
+        })?;
+        if !value.is_finite() || value.fract() != 0.0 {
+            return Err(Error::Protocol(format!(
+                "{} block_until_ms must be an integer",
+                call.name
+            )));
+        }
+        if value < i64::MIN as f64 || value > i64::MAX as f64 {
+            return Err(Error::Protocol(format!(
+                "{} block_until_ms is out of range",
+                call.name
+            )));
+        }
+        value as i64
+    };
+
+    if integer < 0 {
+        return Err(Error::Protocol(format!(
+            "{} block_until_ms is out of range",
+            call.name
+        )));
+    }
+
+    if value.as_i64().is_some() {
+        return Ok(None);
+    }
+
+    let mut normalized_call = call.clone();
+    normalized_call
+        .arguments
+        .as_object_mut()
+        .ok_or_else(|| Error::Protocol(format!("{} arguments must be a JSON object", call.name)))?
+        .insert("block_until_ms".into(), serde_json::Value::from(integer));
+    Ok(Some(normalized_call))
+}
+
 fn is_mcp_auth(call: &ToolCall) -> bool {
     normalized(&call.name) == "callmcptool"
         && call
@@ -89,3 +141,65 @@ pub(super) fn normalized(name: &str) -> String {
         .flat_map(char::to_lowercase)
         .collect()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn tool(name: &str, arguments: serde_json::Value) -> ToolCall {
+        ToolCall {
+            index: 0,
+            call_id: "call-1".into(),
+            model_call_id: "model-call-1".into(),
+            name: name.into(),
+            arguments_text: arguments.to_string(),
+            arguments,
+        }
+    }
+
+    #[test]
+    fn shell_accepts_integer_valued_float_timeout() {
+        let call = tool("Shell", serde_json::json!({
+            "command": "echo ok",
+            "block_until_ms": 45_000.0
+        }));
+
+        let call = normalize_block_until_ms(&call).unwrap().unwrap();
+
+        assert_eq!(call.arguments["block_until_ms"].as_i64(), Some(45_000));
+    }
+
+    #[test]
+    fn await_shell_accepts_integer_valued_scientific_timeout() {
+        let arguments = serde_json::from_str(r#"{"shell_id":"1","block_until_ms":3e4}"#).unwrap();
+        let call = tool("AwaitShell", arguments);
+
+        let call = normalize_block_until_ms(&call).unwrap().unwrap();
+
+        assert_eq!(call.arguments["block_until_ms"].as_u64(), Some(30_000));
+    }
+
+    #[test]
+    fn shell_rejects_fractional_timeout() {
+        let call = tool("Shell", serde_json::json!({
+            "command": "echo ok",
+            "block_until_ms": 30_000.5
+        }));
+
+        let error = normalize_block_until_ms(&call).unwrap_err();
+
+        assert_eq!(error.to_string(), "protocol error: Shell block_until_ms must be an integer");
+    }
+
+    #[test]
+    fn await_shell_rejects_negative_timeout_instead_of_defaulting() {
+        let call = tool("AwaitShell", serde_json::json!({
+            "shell_id": "1",
+            "block_until_ms": -1
+        }));
+
+        let error = normalize_block_until_ms(&call).unwrap_err();
+
+        assert_eq!(error.to_string(), "protocol error: AwaitShell block_until_ms is out of range");
+    }
+}