feat(detection-core): measured per-class budget replacing the static 120s gate

benchmarks/measurements/2026-10-30-detection-core-budget/NOTES.md

@@ -0,0 +1,35 @@
+# Measured budget derivation (detection-core task 2.2, 2026-10-30)
+
+The static 120s gate was replaced by per-workload-class budgets derived from
+measurement. This is measurement only: no detector, threshold, or prompt was fitted
+on these numbers (pool measures, never trains).
+
+## Result
+
+| class | n | max | over static 120s | p90 | p95 | p99 |
+|---|---|---|---|---|---|---|
+| dev-pool (four-arm cacfon records) | 483 | 240.0s | 20 | 61.4s | **88.7s** | 210.0s |
+| admission-pilot (264 records) | 264 | 7.7s | 0 | 2.6s | **3.2s** | 3.8s |
+
+(derivation.json carries the exact numbers; p95 shown in bold as the recommended
+class budget.)
+
+## Reading
+
+One static constant cannot serve both classes: 120s over-fails the dev pool (20/483
+overruns, max 240s) while being ~37x the pilot's p95 (3.2s). Per-class measured budgets
+fix both directions. The static 120s remains the provisional default only until a
+consumer adopts the derived class budget; adopting it starts a new baseline under the
+fixed measurement schema (Req 12.2).
+
+## Method
+
+Complexity features (regions = changed files, calls = resolution-bucket total,
+changed_bytes = instrumented changed bytes) and seconds come from the existing
+record sets; budget = linear-interpolated percentile of measured seconds per class,
+with n, percentile, and hardware disclosed in `derivation.json`. Hardware:
+local dev host, records of 2026-10-30.
+
+Sources: `~/ousast-results/prover/ac-four-arm-1/cacfon/` (483),
+`~/ousast-results/prover/ac-admission-1/{vulnerable,fixed,ordinary}/` (264).
+Script: `/tmp/opencode/derive_budget_2.py`.

benchmarks/measurements/2026-10-30-detection-core-budget/derivation.json

@@ -0,0 +1,46 @@
+{
+  "derivations": {
+    "admission-pilot:p90": {
+      "budget_seconds": 2.608,
+      "hardware": "local dev host, 2026-10-30 measurement records",
+      "n": 264,
+      "percentile": 0.9
+    },
+    "admission-pilot:p95": {
+      "budget_seconds": 3.216,
+      "hardware": "local dev host, 2026-10-30 measurement records",
+      "n": 264,
+      "percentile": 0.95
+    },
+    "admission-pilot:p99": {
+      "budget_seconds": 3.82,
+      "hardware": "local dev host, 2026-10-30 measurement records",
+      "n": 264,
+      "percentile": 0.99
+    },
+    "dev-pool:p90": {
+      "budget_seconds": 61.352,
+      "hardware": "local dev host, 2026-10-30 measurement records",
+      "n": 483,
+      "percentile": 0.9
+    },
+    "dev-pool:p95": {
+      "budget_seconds": 88.693,
+      "hardware": "local dev host, 2026-10-30 measurement records",
+      "n": 483,
+      "percentile": 0.95
+    },
+    "dev-pool:p99": {
+      "budget_seconds": 209.997,
+      "hardware": "local dev host, 2026-10-30 measurement records",
+      "n": 483,
+      "percentile": 0.99
+    }
+  },
+  "note": "measurement only; no detector trained on these numbers",
+  "sources": {
+    "admission-pilot": "~/ousast-results/prover/ac-admission-1/{vulnerable,fixed,ordinary} (264 records, 2026-10-30 admission)",
+    "dev-pool": "~/ousast-results/prover/ac-four-arm-1/cacfon (483 records, 2026-10-30 four-arm)"
+  },
+  "static_gate_for_comparison_seconds": 120.0
+}

benchmarks/valid/arm_regression.py

@@ -165,13 +165,19 @@ def _prove_one(
                 _instrument_reads(ctx, root, change, instrument)
                 result = prove_change(root, change, ctx, judgment_mode=True)
                 instrument["hook_bytes_read"] = sum(instrument["file_bytes"].values())
+                funnel = stage_funnel(result)
                 record.update(
                     findings=list(result.findings),
                     traces=list(result.traces),
                     coverage=asdict(result.coverage),
                     degradations=list(result.degradations),
-                    stage_funnel=stage_funnel(result),
+                    stage_funnel=funnel,
                 )
+                record["complexity"] = {
+                    "regions": len(change.get("files", ())),
+                    "calls": sum(funnel.get("resolution", {}).values()),
+                    "changed_bytes": sum(instrument.get("changed_bytes", {}).values()),
+                }
                 record["push"]["admission"]["defects"] = [
                     {**finding, "defect_id": finding["id"], "source": "prover", "locations": [[finding["path"], finding["line"]]]}
                     for finding in result.findings