0754 — Benchmark runs share configuration and output

Context

Manager still rebuilt Compose images per repetition, translated role settings through a second set of Compose commands, and created a directory separate from the checker’s timestamp directory. Native runtime defaults also lived inside the lifecycle method instead of the caller’s run configuration.

Decision

• Build Compose images once before repetitions. Reuse the invocation’s Compose project and images while recreating its containers and volumes between repetitions.
• Manager constructs one role argument list. Native invokes the binary; Compose invokes that binary in the service container. Only filesystem paths differ. Compose declares infrastructure, not scenario arguments.
• Manager chooses each run directory once. Checker requires that directory through -run-dir, writes its verdict and report there, and retains measurements under its records directory. It creates no timestamp directory. Existing run indexes remain under results//runs.jsonl.
• Native roles inherit Go runtime environment settings. Manager injects no GOMAXPROCS, GOGC, or GOMEMLIMIT defaults. A comparison requiring the former 4/400/2GiB settings supplies them explicitly; fingerprints record the supplied environment and role logs report the effective runtime.
• Keep 0753’s shared role lifecycle, supplied native database ownership, CPU measurements, and failure cleanup. The fixed startup pause is outside this deduplication.

Consequences

Repetitions use the same build, scenario settings have one translation, and logs and verdicts identify the same output directory. Standalone checker invocations must supply a run directory. Historical results and frozen publication commands are unchanged. This supersedes [0753]‘s native runtime preset and establishes the single output directory for its lifecycle.