Module: Legion::MCP::TierRouter

Extended by:
Logging::Helper
Defined in:
lib/legion/mcp/tier_router.rb

Constant Summary collapse

CONFIDENCE_TIER0 = 
0.8
CONFIDENCE_TIER1 = 
0.6

Class Method Summary collapse

Class Method Details

.execute_tool_chain(tool_chain, params, request_id: nil) ⇒ Object 



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# File 'lib/legion/mcp/tier_router.rb', line 117

def execute_tool_chain(tool_chain, params, request_id: nil)
  tool_chain.map do |tool_name|
    tool_class = find_tool_class(tool_name)
    raise ArgumentError, "unknown tool: #{tool_name}" unless tool_class

    mcp_log :info, 'tier_router.tool_call.start',
            request_id: request_id, tool_name: tool_name, params: Utils.summarize_params(params)

    result = if params.empty?
               tool_class.call
             else
               tool_class.call(**params.transform_keys(&:to_sym))
             end

    mcp_log :info, 'tier_router.tool_call.complete',
            request_id: request_id, tool_name: tool_name, result: Utils.summarize_result(result)

    result
  rescue StandardError => e
    handle_exception(e, level: :warn, operation: 'legion.mcp.tier_router.execute_tool_chain')
    mcp_log :warn, 'tier_router.tool_call.failed',
            request_id: request_id, tool_name: tool_name, error: e.message
    raise
  end
end

.find_tool_class(tool_name) ⇒ Object 



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# File 'lib/legion/mcp/tier_router.rb', line 176

def find_tool_class(tool_name)
  return nil unless defined?(Legion::MCP::Server)

  Legion::MCP::Server.tool_registry.find do |klass|
    klass.respond_to?(:tool_name) && klass.tool_name == tool_name
  end
end

.generate_response(results, pattern) ⇒ Object 



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# File 'lib/legion/mcp/tier_router.rb', line 143

def generate_response(results, pattern)
  template = pattern[:response_template]

  if template && transformer_available?
    begin
      client = Legion::Extensions::Transformer::Client.new
      rendered = client.transform(transformation: template, payload: { results: results })
      return rendered[:result] if rendered[:success]
    rescue StandardError => e
      handle_exception(e, level: :debug, operation: 'legion.mcp.tier_router.generate_response')
    end
  end

  results.size == 1 ? results.first : results
end

.mcp_log(level, event, **fields) ⇒ Object 



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# File 'lib/legion/mcp/tier_router.rb', line 18

def mcp_log(level, event, **fields)
  log.public_send(level, "[mcp] #{event} #{Utils.format_fields(fields)}")
end

.normalize_intent(intent) ⇒ Object 



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# File 'lib/legion/mcp/tier_router.rb', line 113

def normalize_intent(intent)
  intent.to_s.strip.downcase.gsub(/\s+/, ' ')
end

.route(intent:, params: {}, context: {}) ⇒ Object

rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/MethodLength, Metrics/PerceivedComplexity



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# File 'lib/legion/mcp/tier_router.rb', line 22

def route(intent:, params: {}, context: {}) # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/MethodLength, Metrics/PerceivedComplexity
  start_time = ::Process.clock_gettime(::Process::CLOCK_MONOTONIC)
  normalized = normalize_intent(intent)
  intent_hash = Digest::SHA256.hexdigest(normalized)
  request_id = Utils.request_id_from(context, params) || "route_#{intent_hash[0, 8]}"

  mcp_log :info, 'tier_router.start',
          request_id: request_id, intent_hash: intent_hash[0, 12],
          intent: Utils.summarize_text(intent),
          params: Utils.summarize_params(params),
          context_keys: context.respond_to?(:keys) ? context.keys.map(&:to_s) : []

  ContextGuard.record_request(intent_hash)

  pattern = Patterns::Store.lookup(intent_hash, request_id: request_id)
  lookup_source = :exact

  unless pattern
    pattern = try_semantic_lookup(normalized, request_id: request_id)
    lookup_source = pattern ? :semantic : :miss
  end

  mcp_log :info, 'tier_router.lookup',
          request_id: request_id, source: lookup_source,
          confidence: pattern&.dig(:confidence)&.round(3),
          tool_chain: Array(pattern&.dig(:tool_chain))

  unless pattern
    mcp_log :info, 'tier_router.decision',
            request_id: request_id, tier: 2, reason: 'no matching pattern'
    return tier2_response('no matching pattern')
  end

  # After semantic lookup, track against the matched pattern's hash, not the incoming intent hash
  matched_hash = pattern[:intent_hash] || intent_hash
  confidence = pattern[:confidence] || 0.0

  if confidence < CONFIDENCE_TIER1
    mcp_log :info, 'tier_router.decision',
            request_id: request_id, tier: 2, reason: 'low confidence',
            confidence: confidence.round(3), tool_chain: Array(pattern[:tool_chain])
    return tier2_response('low confidence')
  end

  if confidence < CONFIDENCE_TIER0
    mcp_log :info, 'tier_router.decision',
            request_id: request_id, tier: 1,
            reason: 'confidence below tier 0 threshold',
            confidence: confidence.round(3), tool_chain: Array(pattern[:tool_chain])
    return tier1_response(pattern, 'confidence below tier 0 threshold')
  end

  guard_result = ContextGuard.check(pattern, params, context)
  mcp_log :info, 'tier_router.guard',
          request_id: request_id, passed: guard_result[:passed], reason: guard_result[:reason]
  unless guard_result[:passed]
    mcp_log :info, 'tier_router.decision',
            request_id: request_id, tier: 1, reason: guard_result[:reason], confidence: confidence.round(3)
    return tier1_response(pattern, guard_result[:reason])
  end

  begin
    mcp_log :info, 'tier_router.execute',
            request_id: request_id, tool_chain: Array(pattern[:tool_chain]),
            params: Utils.summarize_params(params)

    results = execute_tool_chain(pattern[:tool_chain], params, request_id: request_id)
    response = generate_response(results, pattern)
    Patterns::Store.record_hit(matched_hash, request_id: request_id)
    Patterns::Store.learn_response_template(matched_hash, results.first, request_id: request_id) if results.size == 1

    elapsed_ms = ((::Process.clock_gettime(::Process::CLOCK_MONOTONIC) - start_time) * 1000).round(2)
    mcp_log :info, 'tier_router.complete',
            request_id: request_id, tier: 0, latency_ms: elapsed_ms,
            confidence: pattern[:confidence]&.round(3),
            response: Utils.summarize_result(response)
    {
      tier:               0,
      response:           response,
      latency_ms:         elapsed_ms,
      pattern_confidence: pattern[:confidence]
    }
  rescue StandardError => e
    handle_exception(e, level: :warn, operation: 'legion.mcp.tier_router.route')
    mcp_log :warn, 'tier_router.execute.failed',
            request_id: request_id, error: e.message, tool_chain: Array(pattern[:tool_chain])
    Patterns::Store.record_miss(matched_hash, request_id: request_id)
    tier1_response(pattern, "tool chain failed: #{e.message}")
  end
end

.tier1_response(pattern, reason) ⇒ Object 



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# File 'lib/legion/mcp/tier_router.rb', line 188

def tier1_response(pattern, reason)
  { tier: 1, response: nil, pattern: pattern, reason: reason }
end

.tier2_response(reason) ⇒ Object 



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# File 'lib/legion/mcp/tier_router.rb', line 192

def tier2_response(reason)
  { tier: 2, response: nil, reason: reason }
end

.transformer_available? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/legion/mcp/tier_router.rb', line 184

def transformer_available?
  defined?(Legion::Extensions::Transformer::Client)
end

.try_semantic_lookup(normalized_intent, request_id: nil) ⇒ Object 



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# File 'lib/legion/mcp/tier_router.rb', line 159

def try_semantic_lookup(normalized_intent, request_id: nil)
  return nil unless defined?(Legion::MCP::EmbeddingIndex) && Legion::MCP::EmbeddingIndex.populated?

  embedder = Legion::MCP::EmbeddingIndex.instance_variable_get(:@embedder)
  return nil unless embedder

  intent_vector = embedder.call(normalized_intent)
  return nil unless intent_vector

  Patterns::Store.lookup_semantic(intent_vector, request_id: request_id)
rescue StandardError => e
  handle_exception(e, level: :debug, operation: 'legion.mcp.tier_router.try_semantic_lookup')
  mcp_log :debug, 'tier_router.semantic_lookup.failed',
          request_id: request_id, error: e.message
  nil
end