v2.1.0

Upgrade notes

• UPGRADE: a forked child that cannot load a config now raises under the
  default on_init_failure="fail" (minor, qfg-6vno.23). A forked child whose lazy re-initialization fails
  under the default on_init_failure="fail" now raises, matching a fresh boot and sdk-ruby
  (init-failure design B.3 "Fork"; qfg-6vno.23). Before, a recycled worker
  that came up during a delivery outage blocked up to init_timeout_ms on its
  first getter and then silently served code defaults. Now that first content
  read (get, get_string, enabled, keys, ...) raises QuonfigInitError,
  and every later one raises the same error without a new fetch until the
  background update channel installs a config. *_details getters return
  reason="ERROR", error_code="PROVIDER_NOT_READY" instead of raising;
  should_log, with_context, refresh and the health accessors never
  raise it. continue and wait are unchanged, an explicit init() in the
  child still raises as before, and the parent is never touched. This is a
  behavior change on the default mode, approved as minor under Decision 1
  (qfg-6vno.16).
  Decided by Jeff 2026-10-22; this changes init-failure handling, not who
  matches a rule, so no prod corpus scan applies.

• UPGRADE: size caps on delivery payloads (minor, qfg-6vno.20.4; supervisor
  contract "Rule — size caps", qfg-6vno.8). One SSE event is capped at 4 MiB
  (4,194,304 bytes), counting every line of the event, so a multi-line data:
  sum is capped too. An oversized event is not a frame: the connection is a
  failed attempt (backoff grows, never connected, the fallback poller takes
  over), and a later keepalive-only connection does not report connected
  until an envelope installs. A 200 body from /api/v2/configs is capped at
  16 MiB (16,777,216 bytes): a Content-Length over it fails before reading,
  otherwise reading stops at the cap + 1, and the leg fails like a 5xx
  (nothing installed, no ETag stored). Each logs one WARN per oversized
  episode naming the source host and the cap; repeats are DEBUG. The caps are
  constants, not options.

Changed (minor)

• A raise from a user callback is a callback error, not a worker restart
  (minor, qfg-6vno.29; supervisor contract Test 5). A caught raise from
  on_config_update or on_sse_connection_state_change is counted in the
  test-only _chaos_diagnostics()["callback_errors"]
  (quonfig_sdk_callback_errors_total{callback}, callback in
  on_config_update / on_connection_state_change) and no longer bumps the
  Layer 1 restart counter. Both are logged at ERROR with the traceback; an
  on_sse_connection_state_change raise was logged at WARNING without one.
  The diagnostics hook is not public API.

Fixed

• The SSE parser no longer rescans the carried unterminated tail on every
  chunk, so one large event parses in linear time instead of quadratic
  (qfg-6vno.20.4).

• Getters no longer raise on malformed input (minor, error-path behavior
  change, qfg-6vno.14). A context namespace that is not a mapping (e.g.
  contexts={"user": None}) is ignored instead of raising TypeError from
  every getter; a config whose criterion has a non-string propertyName is
  skipped at decode with a WARN (like a malformed weight) instead of raising
  AttributeError for that key; and a telemetry failure (e.g. a context key
  whose __str__ raises) can no longer escape a plain getter. Plain getters
  return the default, *_details keep returning their normal result.

Tests

• The chaos harness reads every asserted value from the SDK: connection_state(),
  fallback_poller_active() and a test-only _chaos_diagnostics() hook (SSE
  connect attempts, Layer 1 restarts, SSE worker liveness; not public API). It no
  longer invents a reconnecting state, reports the layer-2 restart counter
  SKIPPED (the poller has no restart supervisor), fails on an unknown inject or
  process action, and implements the scenario 00 init-failure vocabulary. Chaos
  and failover pins move to ITD v2026.10.21.1, and CI fails when the three ITD
  refs differ (qfg-6vno.5, qfg-6vno.7).
• The chaos probe reads sdkMetric('quonfig_sdk_callback_errors_total', callback=...) from the SDK, and all ITD pins move to v2026.10.22.2 (size
  caps Test 10, callback-error Test 5, scenario 10 on the new counter, regex
  corpus cases) (qfg-6vno.29).