slice 7 escrow: agent contract test + CHANGELOG/REPORT/CLAUDE (v0.9.0)

Agent half of slice-7 close-out finalized: cross-repo wire-contract test
(escrowUploadRequest mirrors the hub), v0.9.0 CHANGELOG entry + REPORT + CLAUDE
version line. No secrets.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

cmd/felhom-agent/escrow_contract_test.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"encoding/json"
+	"reflect"
+	"sort"
+	"testing"
+)
+
+// TestEscrowUploadContract pins the agent→hub escrow wire shape. It MUST match the hub's ingest
+// struct (felhom-hub api.escrowUploadRequest). Cross-repo, no shared module — this is the agent
+// half of the contract guard; the hub has the mirror in its own test.
+func TestEscrowUploadContract(t *testing.T) {
+	b, _ := json.Marshal(escrowUploadRequest{BlobB64: "x", KeyFingerprint: "y", Posture: "z", CreatedAt: "t"})
+	var m map[string]any
+	if err := json.Unmarshal(b, &m); err != nil {
+		t.Fatal(err)
+	}
+	got := make([]string, 0, len(m))
+	for k := range m {
+		got = append(got, k)
+	}
+	sort.Strings(got)
+	want := []string{"blob_b64", "created_at", "key_fingerprint", "posture"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("escrow wire contract drift: got %v want %v (must match the hub ingest struct)", got, want)
+	}
+}