Module: PostHog::MCP::RequestScope Private

Defined in:
lib/posthog/mcp/request_scope.rb

Overview

This module is part of a private API. You should avoid using this module if possible, as it may be removed or be changed in the future.

Request-scoped hand-off from the Streamable HTTP transport to the server extension. The mcp gem re-parses the JSON body between StreamableHTTPTransport#handle_request and Server#handle_json, so the HTTP headers cannot travel with the request object; this is the one place the integration relies on ambient state.

Uses fiber storage (Fiber[], Ruby 3.2+), which is per fiber, isolated per Ractor, and inherited by fibers/threads a tool spawns. Falls back to fiber-local Thread.current[] on Ruby 3.0/3.1.

Constant Summary collapse

KEY =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

:posthog_mcp_request_scope
FIBER_STORAGE =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

Fiber.respond_to?(:[]) && Fiber.respond_to?(:[]=)
HEADER_ENV_KEYS =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future.

Rack env keys for the headers the integration reads, by header name.

{
  'user-agent' => 'HTTP_USER_AGENT',
  'x-anthropic-client' => 'HTTP_X_ANTHROPIC_CLIENT',
  'mcp-session-id' => 'HTTP_MCP_SESSION_ID',
  'mcp-protocol-version' => 'HTTP_MCP_PROTOCOL_VERSION'
}.freeze

Class Method Summary collapse

Class Method Details

.current ⇒ Hash?

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns {headers:, transport:, mint:, session_id:} for the in-flight HTTP request, plus actor: once Instrumentation has resolved identity for it. session_id is the $session_id Instrumentation settled on before running the tool body, and actor the identity it resolved, so a custom event captured inside the tool is attributed to this request - to the right session and the right person - even while another request on the same server is in flight. actor is absent until the request resolves identity, which is what tells Analytics it has none to use.

Returns:

  • (Hash, nil) —

    {headers:, transport:, mint:, session_id:} for the in-flight HTTP request, plus actor: once Instrumentation has resolved identity for it. session_id is the $session_id Instrumentation settled on before running the tool body, and actor the identity it resolved, so a custom event captured inside the tool is attributed to this request - to the right session and the right person - even while another request on the same server is in flight. actor is absent until the request resolves identity, which is what tells Analytics it has none to use.



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# File 'lib/posthog/mcp/request_scope.rb', line 37

def current
  FIBER_STORAGE ? Fiber[KEY] : Thread.current[KEY]
end

.current=(value) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/posthog/mcp/request_scope.rb', line 41

def current=(value)
  if FIBER_STORAGE
    Fiber[KEY] = value
  else
    Thread.current[KEY] = value
  end
end

.headers_from_env(env) ⇒ Hash{String => String}

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns the headers Instrumentation reads, lowercase.

Parameters:

  • headers (Hash{String => String}) —

    lowercase header names

  • transport (Symbol) —

    :http for the Streamable HTTP transport, :other for a transport that publishes no headers (stdio, a custom dispatcher)

  • env (Hash) —

    a Rack env

Returns:

  • (Hash{String => String}) —

    the headers Instrumentation reads, lowercase



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# File 'lib/posthog/mcp/request_scope.rb', line 54

def headers_from_env(env)
  return {} unless env.is_a?(Hash)

  HEADER_ENV_KEYS.each_with_object({}) do |(name, env_key), acc|
    value = env[env_key]
    acc[name] = value if value.is_a?(String) && !value.empty?
  end
end

.with(headers:, transport: :http) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/posthog/mcp/request_scope.rb', line 63

def with(headers:, transport: :http)
  previous = current
  self.current = { headers: headers, transport: transport, mint: nil, session_id: nil }
  yield current
ensure
  self.current = previous
end