Guards for the three cross-field invariants (source timeout vs lease TTL,
stall window vs max TTFT, probe TTL vs slowest timeout) only ran inside
from_env, so the from_settings path could build a GatewaySettings that
violates the class's own documented invariants. Design moves all of them
plus a non-empty sources check into __post_init__ as _validate_* methods,
matching the existing frozen dataclasses in types.py.
Covers two defects left by PR#1: probe_ttl_s was never moved, and an empty
sources tuple leaked a bare 'max() arg is an empty sequence'.
VT migration abandoned (v1.0 scope becomes two projects), Q1 resolved
to Gitea PyPI, Q6 resolved as judge exemption (unwired zero-consumer
eval scaffolding), migration docs annotated with implementation errata,
and the reference/ read-only rule clarified for the worktree workflow.
AIMD ceiling now respects per-source max_concurrency and the pacer is
assembled explicitly in the client; MIN_CALLS parses as strict int;
acceptance doc corrects source-5 attempt count to 549; design and
migration notes aligned with implemented 429/stall/suppression
semantics and AIMD constants documented.
Round 8 forensics caught the healthy source circuit-opened by five
random empty completions (~20% ambient failure rate makes a 5-streak
land every ~3000 attempts), blacking out the only good source for 60s.
When the window holds min_calls samples below the failure-rate
threshold, a streak is noise and no longer opens the gate; cold-start
and low-traffic semantics are unchanged and sudden death of a warm
source is still caught by the rate channel.
Round 6 hit account-level rate throttling the concurrency AIMD cannot
absorb: at 26 req/min the gateway still returned 16% 429s and each one
burned a third of the retry budget. Retry-After-guided 429s now back
off without consuming attempts (gRPC pushback semantics); the retry
loop gains a per-call ceiling using the same dual-condition stall
verdict as quota-wait (local window exceeded AND no global progress).
Round 5 left three residual failure classes; ladder exhaustion (3.2%
of structured calls with a single re-ask) and 429 leakage (5.8%, AIMD
oscillating above the sustainable point) are addressable: re-ask
default goes 1 to 2 (conservative vs instructor's 3) and the AIMD cut
factor drops to 0.5.
Round 3 showed unconditional yield-after-two-failures pushes the third
attempt onto known-bad sources in heterogeneous pools (83% vs 10%
expected success). OutcomeAwareSelector now exposes health(); a failed
source only yields when some untried candidate scores at least half its
health. Health-blind selectors keep the unconditional rule.
P6 round 2 showed routing convergence turns account-level 429s into
the binding constraint (62% throttle rate at full concurrency). Each
source now carries a local AIMD limit: multiplicative cut on 429,
additive growth on success. Over-limit picks queue via the existing
quota-wait poll instead of burning retry budget or tripping the
circuit-open verdict.
Records the human decision to test against the real gateway with real
data instead of building a mock gateway, six execution scenarios with
fault-source mixing, hard invariants scored from our own telemetry,
and the corpus inventory pulled from the lab server.
Classify empty completions as transient per human ruling (fixes flaky
real-gateway smoke and prevents caching empty responses), rename the
factory injection parameter gate to breaker per the frozen design,
rewrite the probe-entry cleanup without except BaseException, declare
python-dotenv explicitly, add a mid-backoff cancellation test, and
record all implementation errata in the design and architecture docs.
Also note that the seven architecture amendments predate the plan,
tighten T12 to independent implementation layers, and add fallback
guidance for read-only reference protocol imports.
Correct the section 6.1 reason enum against actual CHS code, make
retry_after_s a non-optional float, add structured_data to LLMResponse
extensions, finalize the structured parameter type, document SSE
missing-done semantics and watchdog thinking-token liveness, add the
StructuredMW layer to the default onion order, and register
middleware/structured.py in the module map.
iomgaa