diff --git a/lib/towerops/agent/validator.ex b/lib/towerops/agent/validator.ex
index 80c602c0..2c7fba91 100644
--- a/lib/towerops/agent/validator.ex
+++ b/lib/towerops/agent/validator.ex
@@ -191,15 +191,28 @@ defmodule Towerops.Agent.Validator do
       {:error, {:decode_error, "Invalid protobuf message format"}}
   end
 
-  # Validate semantic version format (empty string allowed for backward compat)
+  # Validate version format - accepts either semantic version or RFC 3339 timestamp
+  # Empty string allowed for backward compat
   defp validate_version(""), do: :ok
 
   defp validate_version(version) when is_binary(version) do
-    if String.match?(version, ~r/^\d+\.\d+\.\d+(-[a-zA-Z0-9.]+)?$/) and
-         String.length(version) <= @max_short_string_length do
-      :ok
-    else
-      {:error, {:invalid_version, "Version must be semver format (e.g., 1.2.3)"}}
+    cond do
+      # Semantic version format (backward compatibility with old agents)
+      # Pattern: X.Y.Z or X.Y.Z-suffix
+      String.match?(version, ~r/^\d+\.\d+\.\d+(-[a-zA-Z0-9.]+)?$/) ->
+        if String.length(version) <= @max_short_string_length,
+          do: :ok,
+          else: {:error, {:invalid_version, "Version too long"}}
+
+      # RFC 3339 timestamp format (new agents with compile timestamp)
+      # Pattern: YYYY-MM-DDTHH:MM:SSZ
+      String.match?(version, ~r/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z$/) ->
+        if String.length(version) <= @max_short_string_length,
+          do: :ok,
+          else: {:error, {:invalid_version, "Version too long"}}
+
+      true ->
+        {:error, {:invalid_version, "Version must be semver format (e.g., 1.2.3) or RFC 3339 timestamp"}}
     end
   end
 
diff --git a/test/towerops/agent/validator_test.exs b/test/towerops/agent/validator_test.exs
index f5229ff4..e45f9a89 100644
--- a/test/towerops/agent/validator_test.exs
+++ b/test/towerops/agent/validator_test.exs
@@ -535,6 +535,55 @@ defmodule Towerops.Agent.ValidatorTest do
       assert {:ok, _} = Validator.validate_heartbeat(binary)
     end
 
+    test "accepts RFC 3339 timestamp version format" do
+      heartbeat = %AgentHeartbeat{
+        version: "2025-02-09T15:30:45Z",
+        hostname: "agent01",
+        uptime_seconds: 100,
+        ip_address: ""
+      }
+
+      binary = AgentHeartbeat.encode(heartbeat)
+      assert {:ok, validated} = Validator.validate_heartbeat(binary)
+      assert validated.version == "2025-02-09T15:30:45Z"
+    end
+
+    test "accepts RFC 3339 timestamp with different date/time" do
+      heartbeat = %AgentHeartbeat{
+        version: "2026-12-31T23:59:59Z",
+        hostname: "agent02",
+        uptime_seconds: 200,
+        ip_address: ""
+      }
+
+      binary = AgentHeartbeat.encode(heartbeat)
+      assert {:ok, _} = Validator.validate_heartbeat(binary)
+    end
+
+    test "rejects RFC 3339 timestamp without Z suffix" do
+      heartbeat = %AgentHeartbeat{
+        version: "2025-02-09T15:30:45",
+        hostname: "agent01",
+        uptime_seconds: 100,
+        ip_address: ""
+      }
+
+      binary = AgentHeartbeat.encode(heartbeat)
+      assert {:error, {:invalid_version, _}} = Validator.validate_heartbeat(binary)
+    end
+
+    test "rejects RFC 3339 timestamp with offset instead of Z" do
+      heartbeat = %AgentHeartbeat{
+        version: "2025-02-09T15:30:45+00:00",
+        hostname: "agent01",
+        uptime_seconds: 100,
+        ip_address: ""
+      }
+
+      binary = AgentHeartbeat.encode(heartbeat)
+      assert {:error, {:invalid_version, _}} = Validator.validate_heartbeat(binary)
+    end
+
     test "rejects version with spaces" do
       heartbeat = %AgentHeartbeat{
         version: "1.2 .3",