M6 — Lease expiration + budget + result_chunk + middleware gems + ship

[nficano]

Goal

Lease expiration + budget + progress + result_chunk + middleware gems + ship — the v1.1 finish line.

Scope

• Arcp::Lease::LeaseConstraints (ISO-8601 UTC Z only; Time#utc? guard)
• Arcp::Runtime::LeaseManager#evaluate checks expires_at via Process.clock_gettime(Process::CLOCK_MONOTONIC) on every authority op
• Arcp::Errors::LeaseExpired (retryable: false)
• Arcp::Lease::CostBudget capability parser (CCY:amount grammar) + per-currency counters using BigDecimal
• Decrement on metric { name: cost.*, unit: <ccy>, value: }; try_decrement straight-line (no Async suspension)
• Arcp::Errors::BudgetExhausted (retryable: false)
• progress body — Arcp::Job::Event::Progress
• result_chunk body — Arcp::Job::Event::ResultChunk
• JobContext#stream_result returns an Async::Queue whose each yields ResultChunk bodies
• Reject inline + chunked mix per §8.4
• Trace attrs arcp.lease.expires_at, arcp.budget.remaining
• Samples: samples/lease_expires_at/, samples/cost_budget/, samples/progress/, samples/result_chunk/
• Side gems tagged 1.1.0: arcp-rack, arcp-falcon, arcp-rails, arcp-otel
• docs/concepts/leases.md, docs/guides/{budgets,result-streaming}.md
• CHANGELOG.md v1.1 entry; MIGRATION-v1.1.md final
• Mutation testing (mutant) nightly job: MSI ≥ 95% on lib/arcp/envelope.rb, lib/arcp/session/capability_set.rb, lib/arcp/lease/cost_budget.rb
• Tag arcp 1.1.0; publish to RubyGems

Spec §

§8.4, §9.5, §9.6, §11, §12

Gate

bundle exec rake conformance reports every §4–§12 row passing for v1.0 + v1.1. README + MIGRATION-v1.1.md ship. All 18 samples runnable via ruby samples/<name>/run.rb exiting 0.