Controlled historical/current comparison

The separate paired experiment compares the unmodified historical runtime at 52ac47542a05c0a1263f78a14c04a5c2e6b761f3 with the current production standalone node. It measures a declared set of production changes on one observed Linux environment. It does not replace the August 30 native calibration, rerun the historical full invariant proof, or by itself complete Phase 1. Here, "current" means the candidate revision recorded by each run, not every later repository revision. The retained functional completion and extension results keep those populations and measured source identities separate.

Both arms use the maintained Echo guest. The bootstrap verifies that its component.rs and logic.rs sources are identical across the two revisions. Each arm uses its own ABI-compatible Component Model artifact; both exact components and release executables are retained. The old CLI is an actual historical binary, not the current compatibility facade.

The fixed semantic input and output are the 25 UTF-8 bytes phase0 targeted warm echo. Both arms grant ten billion fuel, 16 MiB memory, 1000 ms wall time and 16384 log bytes, with two cells and three queue slots. Each process prepares one component once, then executes a contiguous sequential population. Full mode collects seven independent pairs with 40 leading warmup calls and 400 measured calls per arm. Smoke mode uses one pair with two warmup and four measured calls and always remains incomplete. Order alternates between control first and candidate first. No observed timing determines selection, and no outlier is removed.

The deliberate treatment includes typed versus dynamic dispatch, the guest ABI, routing, admission, context, log handling and resource accounting. The historical binary has two runtime workers; the current node has two invocation workers and one control worker. The historical cache allows one entry and the current cache allows four, but each observed arm must retain exactly one prepared entry, with fresh stores and no live activation owners after every call. The current arm checks each terminal receipt against retained status and releases its preparation before clean node shutdown. Parent receipts independently record process identity, exit, reaping, closed output readers and removal of temporary data.

Host, kernel, CPU, cgroup/virtualization observations, allocator environment, toolchain, target and effective release recipe must match across the paired processes. Instantaneous load is retained and may vary. The source revisions, executables and components are individually bound rather than falsely required to be identical. A full run requires clean source for both arms. Dirty smoke evidence can validate the machinery but cannot qualify the comparison.

Collect and replay

Build the historical control with the maintained bootstrap helper, supplying pristine historical source and a fresh external build directory. The helper retains the build receipt, logs, release recipe, lockfile, guest sources and staged measurement inputs. It does not change the historical checkout. Use the pinned repository toolchain and invoke the helper with its two positional paths:

bash tools/build_phase1_historical_control.sh \
  /path/to/pristine-historical-checkout /path/to/fresh-historical-control-build

Run the separate smoke profile first:

python3 tools/run_phase1_paired.py --profile smoke \
  --control-source /path/to/pristine-historical-checkout \
  --control-build-dir /path/to/historical-control-build \
  --output target/phase1-paired/smoke-review

--profile full selects the fixed seven-pair population. Builds use the retained release recipe in both profiles. The runner bounds process lifetime and output, preserves unsuccessful attempts, and supervises process groups. Its watchdog does not claim it can forcibly stop arbitrary started operating-system work.

Replay the original suite, then independently regenerate and validate statistics:

python3 tools/validate_phase1_paired.py --suite target/phase1-paired/run/suite.json
python3 tools/aggregate_phase1_paired.py \
  --suite target/phase1-paired/run/suite.json \
  --output target/phase1-paired/run/replayed.json
python3 tools/validate_phase1_paired.py --aggregate target/phase1-paired/run/replayed.json

Keep the relative directory layout when archiving. The aggregate binds its suite; the suite binds every raw report, metadata file, source copy, executable and parent receipt by SHA-256 and byte count. JSON schema shape validation is additional to semantic replay. Neither rehashing a changed sample nor changing an aggregate value can satisfy replay without preserving all cross-file associations and fixed controls.

Read the observations

Each metric names its control and candidate boundaries. Preparation measures the actual preparation API after engine construction, once per process. Current collector revisions call prepare_from_repository and record preparation_scope: repository-acquisition-including-verified-refill, including the checked repository refill. The historical arm still uses its original direct-artifact preparation API. Earlier retained candidate archives keep their original boundary and exact source; they do not acquire this new scope on replay. The separate #100 current/current diagnostic instead warms through its first real RPC, as described in measurement scopes. Warm backend setup, guest call, host calls, reclamation, classification, reusable proof and backend total have separately retained intervals. The guest-call interval includes automatic canonical post-return in both runtimes. Host-call time is a subset of guest-call time. The named post-return interval measures subsequent host accounting; it does not time canonical post-return itself.

Semantic invocation elapsed is a wider-path contrast: the historical prepared envelope through terminal outcome and cell disposition versus the current persistent loopback RPC through terminal receipt. It is labelled separately from backend intervals. Startup segments have different exclusions and remain unmatched. Historical summed cleanup, current gaps between named intervals and legacy residuals are never summed into a fabricated comparable cleanup metric. In particular, backend_total_micros excludes repository acquisition and activation materialization; those occur before backend execution begins.

Each pair retains per-arm distributions and median/p95/p99 differences. Across pairs, summaries use independent process representatives and report variability and lower/equal/higher counts. A zero control produces an explicit undefined percentage, not infinity. Seven descriptive pairs do not establish statistical significance, a universal performance limit, or an isolated causal cost for any one change.

Instrumentation is part of the observed experiment. The historical collector retains a growing sample vector; the current collector streams bounded JSON. Their probes and serialization affect spacing between calls and possible cache or thermal state. Process RSS therefore includes different diagnostic retention and cannot establish an isolated runtime memory saving. Current RPC, retained status and telemetry work also differ from the historical direct runner. The original strict Phase 0 comparison continues to report incompatible historical inputs or environments as not_comparable; this paired method does not relax it.