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# frozen_string_literal: true
module Dispatch
module Adapter
class Claude < Base
# Parses the `anthropic-ratelimit-unified-*` HTTP response headers that
# Anthropic sends back on every API call.
#
# These headers are the most up-to-date quota signal available — they are
# attached to every streaming and non-streaming response without any
# additional requests. The per-window utilization values are floats in
# the range 0.0–1.0 (e.g. 0.073 = 7.3% used).
#
# Example headers:
#
# anthropic-ratelimit-unified-status: allowed
# anthropic-ratelimit-unified-representative-claim: five_hour
# anthropic-ratelimit-unified-fallback: available
# anthropic-ratelimit-unified-fallback-percentage: 0.5
# anthropic-ratelimit-unified-overage-status: rejected
# anthropic-ratelimit-unified-5h-status: allowed
# anthropic-ratelimit-unified-5h-reset: 1774933200
# anthropic-ratelimit-unified-5h-utilization: 0.07
# anthropic-ratelimit-unified-5h-surpassed-threshold: false
# anthropic-ratelimit-unified-7d-status: allowed
# anthropic-ratelimit-unified-7d-utilization: 0.53
# anthropic-ratelimit-unified-7d-reset: 1774933200
# anthropic-ratelimit-unified-7d_sonnet-status: allowed
# anthropic-ratelimit-unified-7d_sonnet-utilization: 0.12
# anthropic-ratelimit-unified-7d_opus-utilization: 0.34
#
# Reference: reverse-engineered by the community via proxy captures and
# subsequently confirmed via Anthropic's leaked source map (2026-03-31).
module RateLimitHeaders
# Per-window information.
WindowInfo = Struct.new(
:window_id, # String — "5h", "7d", "7d_sonnet", "7d_opus"
:utilization, # Float 0.0–1.0 — exact fraction of quota consumed
:status, # String — "allowed" | "exceeded" | "rate_limited"
:reset_at, # Time | nil — when this window resets
:surpassed_threshold, # Boolean | nil — true once the quota limit is crossed
keyword_init: true
)
# Top-level summary of all rate-limit windows on a single response.
Info = Struct.new(
:status, # String — overall: "allowed" | "exceeded" | "rate_limited"
:representative_claim, # String | nil — which window is the binding constraint
:fallback, # String | nil — "available" | "unavailable"
:fallback_percentage, # Float | nil — e.g. 0.5
:overage_status, # String | nil — "approved" | "rejected"
:windows, # Hash{String => WindowInfo} — keyed by window_id
:captured_at, # Time — when these headers were read
:raw_headers, # Hash{String => String} — all unified headers, for debugging
keyword_init: true
) do
# Convenience: utilization for the representative (binding) window.
def binding_utilization
return nil unless representative_claim
win = windows[representative_claim] ||
windows[representative_claim.tr("-", "_")]
win&.utilization
end
# True iff any window reports exceeded or rate_limited status.
def limited?
status == "exceeded" ||
status == "rate_limited" ||
windows.any? { |_, w| w.status != "allowed" }
end
# Human-readable one-liner for debugging.
def summary
parts = windows.map do |wid, w|
pct = w.utilization ? format("%.1f%%", w.utilization * 100) : "?"
reset_str = w.reset_at ? " (resets #{w.reset_at.strftime("%H:%M")})" : ""
"#{wid}: #{pct}#{reset_str} [#{w.status}]"
end
parts.unshift("representative=#{representative_claim}") if representative_claim
parts.unshift("status=#{status}") if status
parts.join(", ")
end
# Serializable hash suitable for JSON logging.
def to_log_hash
{
captured_at: captured_at&.iso8601(3),
status: status,
representative_claim: representative_claim,
fallback: fallback,
fallback_percentage: fallback_percentage,
overage_status: overage_status,
windows: windows.transform_values do |w|
{
utilization: w.utilization,
status: w.status,
reset_at: w.reset_at&.iso8601,
surpassed_threshold: w.surpassed_threshold
}
end,
raw_headers: raw_headers
}
end
end
# Header prefix for all unified rate-limit headers.
HEADER_PREFIX = "anthropic-ratelimit-unified-"
# Known window IDs in the headers.
WINDOW_IDS = %w[5h 7d 7d_sonnet 7d_opus].freeze
module_function
# Parse unified rate-limit headers from a Net::HTTP response.
#
# @param response [Net::HTTPResponse] (or any object that responds to #[])
# @return [Info, nil] nil if no unified headers are present
def parse(response)
raw = extract_raw_headers(response)
return nil if raw.empty?
windows = {}
WINDOW_IDS.each do |wid|
win = parse_window(raw, wid)
windows[wid] = win if win
end
Info.new(
status: raw["status"],
representative_claim: raw["representative-claim"],
fallback: raw["fallback"],
fallback_percentage: raw["fallback-percentage"]&.then(&:to_f),
overage_status: raw["overage-status"],
windows: windows,
captured_at: Time.now,
raw_headers: raw
)
end
# ── Private helpers ─────────────────────────────────────────────────
# Extract all headers whose name starts with the unified prefix.
# Returns a Hash with the prefix stripped from the key.
def extract_raw_headers(response)
result = {}
# Net::HTTPResponse supports each_header (yields lowercase keys)
if response.respond_to?(:each_header)
response.each_header do |name, value|
next unless name.start_with?(HEADER_PREFIX)
short_key = name[(HEADER_PREFIX.length)..]
result[short_key] = value
end
elsif response.respond_to?(:to_hash)
# Fallback for stub/mock objects
response.to_hash.each do |name, values|
downcased = name.downcase
next unless downcased.start_with?(HEADER_PREFIX)
short_key = downcased[(HEADER_PREFIX.length)..]
result[short_key] = Array(values).first.to_s
end
end
result
end
# Parse per-window fields from the raw header map.
# Window keys use hyphens in headers but we normalise to match WINDOW_IDS
# which use underscores for compound names (7d_sonnet, 7d_opus).
def parse_window(raw, wid)
# Header keys use hyphens; WINDOW_IDS use underscores for compound names.
hyphen_id = wid.tr("_", "-")
utilization = raw["#{hyphen_id}-utilization"]&.then(&:to_f)
status = raw["#{hyphen_id}-status"]
reset_epoch = raw["#{hyphen_id}-reset"]
surpassed = raw["#{hyphen_id}-surpassed-threshold"]
# Also check underscore form (some headers use them for 7d_sonnet etc.)
if utilization.nil? && hyphen_id != wid
utilization ||= raw["#{wid}-utilization"]&.then(&:to_f)
status ||= raw["#{wid}-status"]
reset_epoch ||= raw["#{wid}-reset"]
surpassed ||= raw["#{wid}-surpassed-threshold"]
end
# Skip the window entirely if there are no keys for it.
return nil if utilization.nil? && status.nil?
reset_at = reset_epoch ? Time.at(reset_epoch.to_i) : nil
surpassed_bool = surpassed.nil? ? nil : (surpassed.downcase == "true")
WindowInfo.new(
window_id: wid,
utilization: utilization,
status: status || "unknown",
reset_at: reset_at,
surpassed_threshold: surpassed_bool
)
end
end
end
end
end
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