Fix native replay numeric fidelity and retire unused startup dependency

v3-ungated/README.md

@@ -47,9 +47,14 @@ have an `error_code` and no score. Do not treat those as safe classifications.
 | Cohort | Assessed / available | Detections or alerts |
 |---|---:|---|
 | AgentDojo-Traj | 1,159 / 1,220 | 85/352 positives detected (24.1% recall); 20/868 benign cases flagged (2.3% FPR) |
-| Private historical regression | 415 / 610 | 1 false alert |
+| Private historical replay cohort | 415 / 415 | 1 false alert |
 | Private later workload sample | 600 / 1,207 | 3 clear false alerts, 1 uncertain low-impact alert |
 
+The historical source pool contains 610 unique saved calls. Context was reliably
+reconstructed for 415, forming the replay cohort above; the other 195 were
+excluded before scoring because their context remains unresolved. They are not
+runtime skips or successful safe predictions.
+
 The original collected false-positive subset has 539 saved cases, of which 409
 were reconstructed and assessed: Claude Code 0/128 alerts; Codex 1/281. The expanded
 historical panel above includes these cases. These cohorts are not additive.

v3-ungated/evaluation.json

@@ -21,7 +21,10 @@
     "total": 415,
     "assessed": 415,
     "skipped": 0,
-    "alerts": 1
+    "alerts": 1,
+    "source_pool_total": 610,
+    "excluded_before_replay": 195,
+    "exclusion_reason": "original context could not be reliably reconstructed"
   },
   "private_original_flagged_no_risk": {
     "saved": 539,

v3-ungated/native/cmd/merlin/main.go

@@ -2,15 +2,39 @@ package main
 
 import (
 	"bufio"
+	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"os"
 	"time"
 
 	"github.com/kontext-security/merlin/native/stepsafety"
 )
 
+type replayRow struct {
+	ID    string           `json:"id"`
+	Input stepsafety.Input `json:"input"`
+}
+
+func decodeRow(data []byte) (replayRow, error) {
+	var row replayRow
+	decoder := json.NewDecoder(bytes.NewReader(data))
+	decoder.UseNumber()
+	if err := decoder.Decode(&row); err != nil {
+		return row, err
+	}
+	var trailing any
+	if err := decoder.Decode(&trailing); err != io.EOF {
+		if err == nil {
+			err = fmt.Errorf("multiple JSON values on one input line")
+		}
+		return row, err
+	}
+	return row, nil
+}
+
 // Merlin only evaluates these inputs; it never executes the supplied tool calls.
 func main() {
 	ctx := context.Background()
@@ -24,11 +48,8 @@ func main() {
 	scan.Buffer(make([]byte, 65536), 4*1024*1024)
 	output := json.NewEncoder(os.Stdout)
 	for scan.Scan() {
-		var row struct {
-			ID    string           `json:"id"`
-			Input stepsafety.Input `json:"input"`
-		}
-		if err := json.Unmarshal(scan.Bytes(), &row); err != nil {
+		row, err := decodeRow(scan.Bytes())
+		if err != nil {
 			fmt.Fprintln(os.Stderr, "Invalid input JSON:", err)
 			os.Exit(1)
 		}

v3-ungated/native/stepsafety/agreement.go

@@ -10,6 +10,7 @@ import (
 	"golang.org/x/text/cases"
 	"golang.org/x/text/language"
 	"io"
+	"io/fs"
 	"math"
 	"strings"
 	"unicode"
@@ -29,8 +30,8 @@ var agreementModel struct {
 	SparseThreshold    float64          `json:"sparse_threshold"`
 }
 
-func loadAgreementAssets() error {
-	f, err := nativeAssets.Open("model/native/agreement.json.gz")
+func loadAgreementAssets(assets fs.FS) error {
+	f, err := assets.Open("model/native/agreement.json.gz")
 	if err != nil {
 		return err
 	}

v3-ungated/native/stepsafety/native_backend.go

@@ -36,13 +36,7 @@ func newNativeBackend(ctx context.Context, cfg Config) (*nativeBackend, error) {
 	nativeOnce.Do(func() {
 		go func() {
 			defer close(nativeReady)
-			nativeShared.model, nativeShared.tokenizer, nativeShared.err = loadNativeAssets(context.Background())
-			if nativeShared.err == nil {
-				nativeShared.err = loadAgreementAssets()
-				if nativeShared.err == nil {
-					nativeShared.err = loadRequestGateAssets()
-				}
-			}
+			nativeShared.model, nativeShared.tokenizer, nativeShared.err = loadNativeRuntime(context.Background(), nativeAssets)
 		}()
 	})
 	select {
@@ -56,14 +50,27 @@ func newNativeBackend(ctx context.Context, cfg Config) (*nativeBackend, error) {
 	}
 }
 
-func loadNativeAssets(ctx context.Context) (*nativeModel, *tokenizer, error) {
-	names, err := fs.Glob(nativeAssets, "model/native/weights.*.gz")
+// loadNativeRuntime loads only assets used by ungated inference. The retired
+// request-intent asset is retained for historical provenance, never startup.
+func loadNativeRuntime(ctx context.Context, assets fs.FS) (*nativeModel, *tokenizer, error) {
+	model, tok, err := loadNativeAssets(ctx, assets)
+	if err != nil {
+		return nil, nil, err
+	}
+	if err := loadAgreementAssets(assets); err != nil {
+		return nil, nil, err
+	}
+	return model, tok, nil
+}
+
+func loadNativeAssets(ctx context.Context, assets fs.FS) (*nativeModel, *tokenizer, error) {
+	names, err := fs.Glob(assets, "model/native/weights.*.gz")
 	if err != nil || len(names) != 5 {
 		return nil, nil, errors.New("missing embedded native weights")
 	}
 	readers := make([]io.Reader, 0, len(names))
 	for _, name := range names {
-		f, err := nativeAssets.Open(name)
+		f, err := assets.Open(name)
 		if err != nil {
 			return nil, nil, err
 		}
@@ -83,7 +90,7 @@ func loadNativeAssets(ctx context.Context) (*nativeModel, *tokenizer, error) {
 	if err != nil {
 		return nil, nil, err
 	}
-	f, err := nativeAssets.Open("model/native/tokenizer.json.gz")
+	f, err := assets.Open("model/native/tokenizer.json.gz")
 	if err != nil {
 		return nil, nil, err
 	}

v3-ungated/release_manifest.json

@@ -10,16 +10,16 @@
       "size": 271
     },
     "README.md": {
-      "sha256": "5d4285e2dd08af2d9a449889780ab2cf55c8ba13c1d8154aae04c734b2b04128",
-      "size": 4424
+      "sha256": "ddf197582c7f06225cec0e4e171898449e5040b40e524b87addbf53f3c38ae29",
+      "size": 4709
     },
     "evaluation.json": {
-      "sha256": "186ec26dd500b5f8791283a619200450c0f10e523ce3faca92a296f6acec1562",
-      "size": 1517
+      "sha256": "697e6e9e0b5dbdad78a002bfea07c0771a02a46195994f687a76c7d59750454d",
+      "size": 1662
     },
     "native/cmd/merlin/main.go": {
-      "sha256": "0a9bbc83520ef46b1b3fc031f16fb2315f7a94d73e8dfef0d78374e64e466376",
-      "size": 1414
+      "sha256": "2771e870f89ddbebcdd6e1ef8a8b9020392907f7ce18808e51d64014ea9b1ee4",
+      "size": 1828
     },
     "native/go.mod": {
       "sha256": "97ffbb6542f80e9cbc14bf46354388a7ba0ce18a1ad4822b64c750b7eda7abe4",
@@ -30,8 +30,8 @@
       "size": 312
     },
     "native/stepsafety/agreement.go": {
-      "sha256": "a19ce6cba08771b455741ba7d2622334636c50b7ffde44fc98341c767f1d2363",
-      "size": 3798
+      "sha256": "b93a6d46e014178b2389511e4cb3c2b7bf404edbd9dc257dc186b608659f69ac",
+      "size": 3813
     },
     "native/stepsafety/context.go": {
       "sha256": "616f619ec4ff787d810085e1566836d13e5106ec6ee42a086411999329dd1563",
@@ -106,8 +106,8 @@
       "size": 454
     },
     "native/stepsafety/native_backend.go": {
-      "sha256": "e94731e7b57cd0bdac1b045dd76f10fcf8690a5bec67ef2b5f1b97d7141f97b1",
-      "size": 3611
+      "sha256": "95ba17ffef0d6f59bb04a8e650230ffab72fca3687ab52ab9ee03d459d879607",
+      "size": 3902
     },
     "native/stepsafety/native_linear_arm64.go": {
       "sha256": "2a510eb9fc849bdf59d4e13fc9288dc14bca41034fb307f76f84ab30d49cb53b",