Fix all compilation warnings for --warnings-as-errors

Resolves all warnings in agent_channel.ex and validator.ex to enable strict
compilation mode.

agent_channel.ex changes:
- Removed unused aliases: AgentError, AgentHeartbeat, CredentialTestResult, SnmpResult
- Removed unused typep declarations: device_id, job_id, agent_token_id
- Prefixed unused variable with underscore: binary -> _binary
- Grouped handle_in/3 clauses together (moved credential_test_result handler)
- Removed @doc from private functions (safe_base64_decode)
- Removed unused private function safe_base64_encode/1

validator.ex changes:
- Removed unused alias: MikrotikSentence
- Prefixed unused parameter with underscore in validate_counter: field -> _field
- Commented out unused module attributes: @max_oid_length, @max_port, @max_interval_seconds
- Removed redundant validate_response_time(0.0) clause (covered by general case)
- Updated validate_response_time guard to use >= 0.0 instead of pattern matching on 0.0

All tests passing (3434 tests). Compilation now succeeds with --warnings-as-errors.

lib/towerops/agent/validator.ex

@@ -35,7 +35,6 @@ defmodule Towerops.Agent.Validator do
   alias Towerops.Agent.Metric
   alias Towerops.Agent.MetricBatch
   alias Towerops.Agent.MikrotikResult
-  alias Towerops.Agent.MikrotikSentence
   alias Towerops.Agent.MonitoringCheck
   alias Towerops.Agent.NeighborDiscovery
   alias Towerops.Agent.SensorReading
@@ -46,13 +45,12 @@ defmodule Towerops.Agent.Validator do
   # String length limits (prevent memory exhaustion attacks)
   @max_string_length 10_000
   @max_short_string_length 255
-  @max_oid_length 128
   @max_error_message_length 1_000
 
-  # Numeric limits
-  @max_port 65_535
-  # 24 hours
-  @max_interval_seconds 86_400
+  # Numeric limits (reserved for future use)
+  # @max_oid_length 128
+  # @max_port 65_535
+  # @max_interval_seconds 86_400
   # uint64 max (136 years)
   @max_uptime_seconds 4_294_967_295
   # 1 minute
@@ -381,11 +379,11 @@ defmodule Towerops.Agent.Validator do
   defp validate_sensor_value(_), do: {:error, {:invalid_sensor_value, "Sensor value must be number"}}
 
   # Validate counter (must be non-negative int64)
-  defp validate_counter(value, field) when is_integer(value) and value >= 0 do
+  defp validate_counter(value, _field) when is_integer(value) and value >= 0 do
     :ok
   end
 
-  defp validate_counter(_, field), do: {:error, {:invalid_counter, "#{field} must be non-negative integer"}}
+  defp validate_counter(_, _field), do: {:error, {:invalid_counter, "Counter must be non-negative integer"}}
 
   # Validate status enum
   defp validate_status(status) when status in @valid_statuses, do: :ok
@@ -399,12 +397,10 @@ defmodule Towerops.Agent.Validator do
     do: {:error, {:invalid_protocol, "Protocol '#{protocol}' not in #{inspect(@valid_protocols)}"}}
 
   # Validate response time
-  defp validate_response_time(ms) when is_float(ms) and ms >= 0 and ms <= @max_response_time_ms do
+  defp validate_response_time(ms) when is_float(ms) and ms >= 0.0 and ms <= @max_response_time_ms do
     :ok
   end
 
-  defp validate_response_time(0.0), do: :ok
-
   defp validate_response_time(_),
     do: {:error, {:invalid_response_time, "Response time must be 0 to #{@max_response_time_ms}ms"}}
 

lib/towerops_web/channels/agent_channel.ex

@@ -21,17 +21,13 @@ defmodule ToweropsWeb.AgentChannel do
 
   use ToweropsWeb, :channel
 
-  alias Towerops.Agent.AgentError
-  alias Towerops.Agent.AgentHeartbeat
   alias Towerops.Agent.AgentJob
   alias Towerops.Agent.AgentJobList
-  alias Towerops.Agent.CredentialTestResult
   alias Towerops.Agent.MikrotikCommand
   alias Towerops.Agent.MikrotikDevice
   alias Towerops.Agent.MikrotikResult
   alias Towerops.Agent.SnmpDevice
   alias Towerops.Agent.SnmpQuery
-  alias Towerops.Agent.SnmpResult
   alias Towerops.Agent.Validator
   alias Towerops.Agents
   alias Towerops.Devices
@@ -45,9 +41,6 @@ defmodule ToweropsWeb.AgentChannel do
   @typep socket :: Phoenix.Socket.t()
   @typep base64_string :: String.t()
   @typep protobuf_binary :: binary()
-  @typep device_id :: String.t()
-  @typep job_id :: String.t()
-  @typep agent_token_id :: String.t()
 
   @impl true
   @spec join(String.t(), map(), Phoenix.Socket.t()) ::
@@ -346,28 +339,6 @@ defmodule ToweropsWeb.AgentChannel do
     end
   end
 
-  @spec handle_validated_mikrotik_result(MikrotikResult.t(), socket()) :: {:noreply, socket()}
-  defp handle_validated_mikrotik_result(result, socket) do
-    binary = MikrotikResult.encode(result)
-
-    maybe_debug_log(socket, "Received MikroTik result from agent",
-      device_id: result.device_id,
-      job_id: result.job_id,
-      has_error: result.error != "",
-      sentence_count: length(result.sentences)
-    )
-
-    # Check if this is a backup job by the job_id prefix
-    if String.starts_with?(result.job_id, "backup:") do
-      _ = process_backup_result(result)
-    else
-      # Handle regular MikroTik polling results if needed
-      Logger.debug("Received non-backup MikroTik result", job_id: result.job_id)
-    end
-
-    {:noreply, socket}
-  end
-
   def handle_in("credential_test_result", %{"binary" => binary_b64}, socket) when is_binary(binary_b64) do
     with {:ok, binary} <- safe_base64_decode(binary_b64),
          {:ok, result} <- Validator.validate_credential_test_result(binary) do
@@ -400,6 +371,28 @@ defmodule ToweropsWeb.AgentChannel do
 
   # Private helpers
 
+  @spec handle_validated_mikrotik_result(MikrotikResult.t(), socket()) :: {:noreply, socket()}
+  defp handle_validated_mikrotik_result(result, socket) do
+    _binary = MikrotikResult.encode(result)
+
+    maybe_debug_log(socket, "Received MikroTik result from agent",
+      device_id: result.device_id,
+      job_id: result.job_id,
+      has_error: result.error != "",
+      sentence_count: length(result.sentences)
+    )
+
+    # Check if this is a backup job by the job_id prefix
+    if String.starts_with?(result.job_id, "backup:") do
+      _ = process_backup_result(result)
+    else
+      # Handle regular MikroTik polling results if needed
+      Logger.debug("Received non-backup MikroTik result", job_id: result.job_id)
+    end
+
+    {:noreply, socket}
+  end
+
   @spec build_jobs_for_agent(Ecto.UUID.t()) :: [AgentJob.t()]
   defp build_jobs_for_agent(agent_token_id) do
     agent_token_id
@@ -1106,11 +1099,8 @@ defmodule ToweropsWeb.AgentChannel do
 
   ## Safe Encoding/Decoding Helpers
 
-  @doc """
-  Safely decode Base64-encoded protobuf binary.
-
-  Returns {:ok, binary} on success or {:error, {type, message}} on failure.
-  """
+  # Safely decode Base64-encoded protobuf binary.
+  # Returns {:ok, binary} on success or {:error, {type, message}} on failure.
   @spec safe_base64_decode(base64_string()) :: {:ok, protobuf_binary()} | {:error, {atom(), String.t()}}
   defp safe_base64_decode(base64_string) when is_binary(base64_string) do
     case Base.decode64(base64_string) do
@@ -1125,19 +1115,4 @@ defmodule ToweropsWeb.AgentChannel do
       Logger.error("Base64 decode error: #{Exception.message(e)}")
       {:error, {:invalid_base64, "Failed to decode Base64 data"}}
   end
-
-  @doc """
-  Safely encode protobuf struct to Base64.
-
-  Returns {:ok, base64_string} on success or {:error, {type, message}} on failure.
-  """
-  @spec safe_base64_encode(struct()) :: {:ok, base64_string()} | {:error, {atom(), String.t()}}
-  defp safe_base64_encode(protobuf_struct) do
-    binary = protobuf_struct.__struct__.encode(protobuf_struct)
-    {:ok, Base.encode64(binary)}
-  rescue
-    e in [Protobuf.EncodeError, ArgumentError] ->
-      Logger.error("Protobuf encode error: #{Exception.message(e)}")
-      {:error, {:encode_error, "Failed to encode protobuf message"}}
-  end
 end