Qualify the complete build runner on native Machines #809

Parent

Build runner spec (#798)

What to build

Qualify the assembled feature through the existing release process and close the evidence gaps that require real Machines. Earlier tickets own their own regression tests; this ticket proves their composition and packaging, not a deferred generic test suite or a new execution engine.

Acceptance criteria

• Run the user-visible Dockerfile and Railpack workflows from packaged musl CLI/daemon artifacts on real Machines. Cover local default, explicit remote target, automatic remote selection and local override; remote operation must not require a local Docker daemon. Test the tools actually provisioned by the product, not a manually prepared developer-only stack.
• Build and Deploy a Railpack application across native AMD64 and native ARM64 Machines, inspecting complete source content and destination-selected variants, then running the application with external-registry fallback disabled. Include an incomplete peer and prove it cannot supply an absent variant. Exercise both recipes' single-platform output and the deliberate multiple-platform Dockerfile refusal.
• Verify the composition of fixed source, separate private variables/provider-once behavior, Service image dependencies, exact-image identity across requested-tag reuse, all-Builds-before-application-mutation, per-Machine transfer outcomes, ordinary/Data Loss Confirmation, and prepare-once Deploy. Cover changed platform requirements without automatic rebuilding or application relocation.
• Exercise admitted and queued cancellation/disconnect, daemon restart, timeout and resource policy through packaged tools, including truthful unknown termination and safe subsequent reuse. Demonstrate persistent cache across builder recreation and deliberate cache clearing without unrelated Docker-data loss. Reuse lower-rung evidence rather than duplicating every policy permutation on real Machines.
• Use the existing rung-5 release qualification process and register any new rung-4 informing binaries correctly. Record exact artifact/tool versions, native hardware/platform observations, runnable commands, completed/failed/unattempted cases and evidence links. Update product-path evidence only for tests that exist and pass; the retained prototype and emulated ARM64 never count as release Authority.
• Document the actual supported Compose options, recipe/location defaults, registry-free delivery, host limits/cache controls, cancellation/queue behavior and explicit v1 refusals alongside the user-facing workflow. Do not claim Cloud/polling/provider support, full Compose compatibility, hard disk quotas, or hardened untrusted multi-tenant execution.
• Confirm the final implementation still exposes capture and execute rather than leaking per-platform, upload or cleanup orchestration into callers. Remove temporary busy refusals and any now-unused transition paths left by earlier slices. Rust fixes follow the required implementation and incremental four-axis-review workflow; documentation/qualification scripts alone do not trigger a Rust review gate.

Blocked by

• #806 — Deploy Railpack images across mixed-architecture Machines
• #807 — Queue and cancel Builds on one Machine
• #808 — Enforce build resource and cache policy on the execution host