feat(measurement): corpus-wide LOOM vs wasm-opt harness + measured wins on components (v0.9.0 PR-P)

docs/measurements/v0.9.0-corpus-baseline.md

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+# v0.9.0 Corpus Baseline -- LOOM vs wasm-opt -O3
+
+_Generated by `scripts/measure_corpus.sh` at `2026-05-14T16:46:17Z`._
+
+- LOOM commit: `723f6a5844019b6f43c888cbecb1e0132cd74f53`
+- LOOM branch: `release/v0.9.0-pr-p-corpus-harness`
+- LOOM version: `loom 0.8.0`
+- wasm-opt: `wasm-opt version 116 (version_116)` (used)
+- wasm-tools: `wasm-tools 1.243.0`
+
+## Headline
+
+On this corpus (only workloads where both LOOM and wasm-opt produced valid output): LOOM produced a **smaller** output than wasm-opt on: gale. 
+
+Missing fixtures (skipped, marked `n/a`):
+- `httparse`
+- `nom_numbers`
+- `state_machine`
+- `json_lite`
+- `loom`
+- `calculator`
+
+## Results
+
+| Workload | Baseline | LOOM | wasm-opt -O3 | wasm-opt -> LOOM | LOOM Δ% vs base | wasm-opt Δ% vs base | Note |
+|---|---:|---:|---:|---:|---:|---:|---|
+| gale | 1941 | 1846 | 1925 | 1846 | -4,9 | -0,8 | kernel-FFI fixture |
+| httparse | n/a | n/a | n/a | n/a | n/a | n/a | HTTP parser |
+| nom_numbers | n/a | n/a | n/a | n/a | n/a | n/a | parser-combinator primitives |
+| state_machine | n/a | n/a | n/a | n/a | n/a | n/a | FSM kernel |
+| json_lite | n/a | n/a | n/a | n/a | n/a | n/a | minimal JSON tokenizer |
+| loom | n/a | n/a | n/a | n/a | n/a | n/a | LOOM self-build (dogfood target) |
+| calculator | n/a | n/a | n/a | n/a | n/a | n/a | component-shaped fixture |
+| calculator_root | 2337724 | 2327794 | error | n/a | -0,4 | -100,0 | 2.3 MB component (root, large) |
+| simple_component | 261 | 212 | error | n/a | -18,8 | -100,0 | tiny component (adapter-heavy) |
+| calc_component | 442 | 392 | error | n/a | -11,3 | -100,0 | small component (adapter-heavy) |
+
+## Methodology
+
+For each workload (fixture path is relative to repo root):
+1. Record baseline byte count via `wc -c` and code-section size via `wasm-tools dump`.
+2. Run `loom optimize <fixture> -o <name>.loom.wasm`.
+3. Run `wasm-opt -O3 <fixture> -o <name>.wopt.wasm` (skipped if wasm-opt unavailable).
+4. Re-run LOOM on the wasm-opt output (`wasm-opt -> LOOM` column).
+5. Validate every output via `wasm-tools validate`. **A validation failure is a HARD ERROR** -- the harness aborts with exit code 2.
+
+Conventions:
+- Δ% is `(out - base) / base * 100`. Negative means smaller (better).
+- A row is flagged :red_circle: if LOOM grew the file vs. baseline, or if wasm-opt beats LOOM by more than 1% of baseline.
+- Outputs of every run are in `/tmp/loom-measure-corpus` for forensic inspection.
+
+## Reproducing
+
+```bash
+# Build LOOM first (Z3 verification enabled)
+Z3_SYS_Z3_HEADER=/opt/homebrew/include/z3.h \
+  LIBRARY_PATH=/opt/homebrew/lib cargo build --release
+
+# Run the harness
+bash scripts/measure_corpus.sh
+```