diff --git a/contracts/cultmesh/authority-route-vectors.json b/contracts/cultmesh/authority-route-vectors.json
new file mode 100644
index 00000000..76ec61f2
--- /dev/null
+++ b/contracts/cultmesh/authority-route-vectors.json
@@ -0,0 +1,44 @@
+{
+  "nowUnixMilliseconds": 1800000000000,
+  "odinRoot": {
+    "keyId": "odin-vector",
+    "x": "shJLGtmRrW6D87VQKv0xYQekLIfEkeN7dVawwpmIKWM=",
+    "y": "iR6Gx3aVCghzSyo7TqXqr+1397L73KDNZuzN2cZ55IE="
+  },
+  "route": {
+    "verseId": "aetheria",
+    "authorityRuntimeId": "aetheria-daemon",
+    "endpoint": "wss://provider.example/mesh",
+    "protocolIds": [
+      "cultmesh.content.v1",
+      "cultmesh.documents.v1"
+    ],
+    "priority": 7,
+    "generation": "vector-generation-1",
+    "certificate": {
+      "providerKey": {
+        "keyId": "provider-vector",
+        "x": "6XIvgx3W1q7lJFEV0yYbeKWNFgssq54BHBuh9gCwcH8=",
+        "y": "oi1FiKraueLic+VemzOx18MNwG6thmZMUWeqNw6vNOk="
+      },
+      "odinKeyId": "odin-vector",
+      "issuedAtUnixMilliseconds": 1799999940000,
+      "expiresAtUnixMilliseconds": 1800003600000,
+      "signature": "ZHuELFuCNNfbJt1T2mx1D9ZHXyxBedacDetmryMYhWKQxfROncltymkmL5KXl+1h8tDK6NytJCGy+7mYlb/DMA=="
+    }
+  },
+  "sessionProof": {
+    "request": {
+      "schemaVersion": "cultmesh.session_open.v2",
+      "messageId": "vector-message-1",
+      "sourceRuntimeId": "vector-consumer",
+      "verseId": "aetheria",
+      "authorityRuntimeId": "aetheria-daemon",
+      "protocolId": "cultmesh.documents.v1",
+      "routeGeneration": "vector-generation-1",
+      "clientNonce": "VczqjH8NdBaOb+rh8xb6P0xZjWD1el2ReNB8Vbp52ko="
+    },
+    "providerKeyId": "provider-vector",
+    "providerSignature": "6kGxSu/pwcR4lzh/7Av9nhblVIwIwVFzB7kY34vVvkpaFAbAxt8mWqIyZDTftE28G1g+NL4Ea41C3QsuImmkaA=="
+  }
+}
diff --git a/packages/cultnet-ts/package.json b/packages/cultnet-ts/package.json
index 2f4b74f1..d34278f5 100644
--- a/packages/cultnet-ts/package.json
+++ b/packages/cultnet-ts/package.json
@@ -14,6 +14,11 @@
       "types": "./dist/contracts.d.ts",
       "require": "./dist/contracts.js",
       "default": "./dist/contracts.js"
+    },
+    "./authority": {
+      "types": "./dist/cultmesh-authority.d.ts",
+      "require": "./dist/cultmesh-authority.js",
+      "default": "./dist/cultmesh-authority.js"
     }
   },
   "files": [
diff --git a/packages/cultnet-ts/src/cultmesh-authority.ts b/packages/cultnet-ts/src/cultmesh-authority.ts
new file mode 100644
index 00000000..c579f347
--- /dev/null
+++ b/packages/cultnet-ts/src/cultmesh-authority.ts
@@ -0,0 +1,192 @@
+// The one TypeScript implementation of CultMesh route verification.
+//
+// Browser-safe by construction: only `crypto.subtle`, `TextEncoder`, `atob`,
+// `btoa`, `URL`, `DataView` and `Uint8Array`. No `node:` import. The browser
+// WebSocket client and the Node realtime consumer verify the same route bytes
+// through the same functions; the C# reference is
+// `src/GameCult.Mesh/CultMeshAuthorityProof.cs`.
+
+import type { CultMeshSessionOpenMessage } from "./contracts";
+
+export interface CultMeshAuthorityIdentity {
+  verseId: string;
+  authorityRuntimeId: string;
+}
+
+export interface CultMeshAuthorityRouteView extends CultMeshAuthorityIdentity {
+  endpoint: string;
+  protocolId?: string;
+  protocolIds?: readonly string[];
+  priority?: number;
+  generation: string;
+  certificate?: CultMeshAuthorityRouteCertificate;
+}
+
+export interface CultMeshP256PublicKey {
+  keyId: string;
+  x: string;
+  y: string;
+}
+
+export interface CultMeshAuthorityRouteCertificate {
+  providerKey: CultMeshP256PublicKey;
+  odinKeyId: string;
+  issuedAtUnixMilliseconds: number;
+  expiresAtUnixMilliseconds: number;
+  signature: string;
+}
+
+export type CultMeshAuthorityTrustMode = "authenticated-remote" | "local-development";
+
+export interface CultMeshAuthorityTrustPolicy {
+  mode: CultMeshAuthorityTrustMode;
+  odinRoots?: readonly CultMeshP256PublicKey[];
+  now?: () => number;
+}
+
+export async function verifyAuthorityRoute(
+  route: CultMeshAuthorityRouteView,
+  trust: CultMeshAuthorityTrustPolicy,
+): Promise<void> {
+  const certificate = route.certificate;
+  if (!certificate) {
+    if (trust.mode === "local-development" && isLoopbackEndpoint(route.endpoint)) return;
+    throw new Error("Remote CultMesh routes require an Odin-signed authority certificate.");
+  }
+  if (!isProtectedEndpoint(route.endpoint) && !(trust.mode === "local-development" && isLoopbackEndpoint(route.endpoint))) {
+    throw new Error("Authenticated remote CultMesh routes require TLS or QUIC channel protection.");
+  }
+  const now = trust.now?.() ?? Date.now();
+  if (now < certificate.issuedAtUnixMilliseconds || now >= certificate.expiresAtUnixMilliseconds) {
+    throw new Error("The Odin route certificate is not currently valid.");
+  }
+  const root = trust.odinRoots?.find(candidate => candidate.keyId === certificate.odinKeyId);
+  if (!root) throw new Error(`Odin key '${certificate.odinKeyId}' is not trusted by this consumer.`);
+  if (!await verifyP256(root, canonicalRoute(route), certificate.signature)) {
+    throw new Error("The Odin route certificate signature is invalid.");
+  }
+}
+
+/** Verifies the provider's session proof over the accepted handshake. */
+export function verifyProviderSessionProof(
+  request: CultMeshSessionOpenMessage,
+  endpoint: string,
+  providerKey: CultMeshP256PublicKey,
+  signatureBase64: string,
+): Promise<boolean> {
+  return verifyP256(providerKey, canonicalSession(request, endpoint), signatureBase64);
+}
+
+export function canonicalRoute(route: CultMeshAuthorityRouteView): Uint8Array {
+  const certificate = route.certificate!;
+  return canonicalFields(
+    "gamecult.cultmesh.route-certificate.v1",
+    route.verseId,
+    route.authorityRuntimeId,
+    route.endpoint,
+    [...(route.protocolIds ?? [route.protocolId ?? "cultmesh.documents.v1"])].sort().join(""),
+    String(route.priority ?? 0),
+    route.generation,
+    certificate.providerKey.keyId,
+    certificate.providerKey.x,
+    certificate.providerKey.y,
+    certificate.odinKeyId,
+    String(certificate.issuedAtUnixMilliseconds),
+    String(certificate.expiresAtUnixMilliseconds),
+  );
+}
+
+export function canonicalSession(request: CultMeshSessionOpenMessage, endpoint: string): Uint8Array {
+  return canonicalFields(
+    "gamecult.cultmesh.session-proof.v1",
+    request.clientNonce,
+    request.messageId,
+    request.sourceRuntimeId,
+    request.verseId,
+    request.authorityRuntimeId,
+    request.protocolId,
+    endpoint,
+    request.routeGeneration,
+  );
+}
+
+export function canonicalFields(...values: string[]): Uint8Array {
+  const encoder = new TextEncoder();
+  const encoded = values.map(value => encoder.encode(value));
+  const total = encoded.reduce((sum, value) => sum + 4 + value.byteLength, 0);
+  const result = new Uint8Array(total);
+  const view = new DataView(result.buffer);
+  let offset = 0;
+  for (const value of encoded) {
+    view.setUint32(offset, value.byteLength, false);
+    offset += 4;
+    result.set(value, offset);
+    offset += value.byteLength;
+  }
+  return result;
+}
+
+export async function verifyP256(
+  key: CultMeshP256PublicKey,
+  payload: Uint8Array,
+  signatureBase64: string,
+): Promise<boolean> {
+  try {
+    const x = base64ToBytes(key.x);
+    const y = base64ToBytes(key.y);
+    const signature = base64ToBytes(signatureBase64);
+    if (x.byteLength !== 32 || y.byteLength !== 32 || signature.byteLength !== 64) return false;
+    const raw = new Uint8Array(65);
+    raw[0] = 4;
+    raw.set(x, 1);
+    raw.set(y, 33);
+    const publicKey = await crypto.subtle.importKey(
+      "raw",
+      raw.slice().buffer as ArrayBuffer,
+      { name: "ECDSA", namedCurve: "P-256" },
+      false,
+      ["verify"],
+    );
+    return await crypto.subtle.verify(
+      { name: "ECDSA", hash: "SHA-256" },
+      publicKey,
+      signature.slice().buffer as ArrayBuffer,
+      payload.slice().buffer as ArrayBuffer,
+    );
+  } catch {
+    return false;
+  }
+}
+
+export function isLoopbackEndpoint(value: string): boolean {
+  try {
+    const host = new URL(value).hostname.replace(/^\[|\]$/g, "").toLowerCase();
+    return host === "localhost" || host === "127.0.0.1" || host === "::1";
+  } catch {
+    return false;
+  }
+}
+
+/** The C# rule (`CultMeshAuthorityProof.cs`, `IsProtected`): wss, https, or any scheme containing "quic". */
+export function isProtectedEndpoint(value: string): boolean {
+  let scheme: string;
+  try {
+    scheme = new URL(value).protocol.slice(0, -1).toLowerCase();
+  } catch {
+    return false;
+  }
+  return scheme === "wss" || scheme === "https" || scheme.includes("quic");
+}
+
+export function bytesToBase64(bytes: Uint8Array): string {
+  let binary = "";
+  for (let offset = 0; offset < bytes.length; offset += 0x8000) {
+    binary += String.fromCharCode(...bytes.subarray(offset, offset + 0x8000));
+  }
+  return btoa(binary);
+}
+
+export function base64ToBytes(value: string): Uint8Array {
+  const binary = atob(value);
+  return Uint8Array.from(binary, character => character.charCodeAt(0));
+}
diff --git a/packages/cultnet-ts/src/index.ts b/packages/cultnet-ts/src/index.ts
index 140526c5..e9260122 100644
--- a/packages/cultnet-ts/src/index.ts
+++ b/packages/cultnet-ts/src/index.ts
@@ -62,6 +62,24 @@ export {
   type GhostlightVariableMap,
   type GhostlightWorldState,
 } from "./contracts";
+export {
+  base64ToBytes,
+  bytesToBase64,
+  canonicalFields,
+  canonicalRoute,
+  canonicalSession,
+  isLoopbackEndpoint,
+  isProtectedEndpoint,
+  verifyAuthorityRoute,
+  verifyP256,
+  verifyProviderSessionProof,
+  type CultMeshAuthorityIdentity,
+  type CultMeshAuthorityRouteCertificate,
+  type CultMeshAuthorityRouteView,
+  type CultMeshAuthorityTrustMode,
+  type CultMeshAuthorityTrustPolicy,
+  type CultMeshP256PublicKey,
+} from "./cultmesh-authority";
 export { encodeFrame, LengthPrefixedMessageFramer } from "./framing";
 export { CultNetPeer, createTcpFramedCultNetPeer, type CultNetPeerEvents, type CultNetPeerSchemaCatalogRequestOptions, type CultNetPeerShardCatalogRequestOptions, type TcpFramedCultNetPeerOptions } from "./peer";
 export {
diff --git a/packages/cultnet-ts/test/cultmesh-authority.test.ts b/packages/cultnet-ts/test/cultmesh-authority.test.ts
new file mode 100644
index 00000000..cb3a62da
--- /dev/null
+++ b/packages/cultnet-ts/test/cultmesh-authority.test.ts
@@ -0,0 +1,238 @@
+// The shared CultMesh route verifier, pinned rule by rule.
+//
+// Routes here are signed with `node:crypto` and verified through the shared
+// module. The transcript bytes themselves are pinned by
+// `contracts/cultmesh/authority-route-vectors.json`, which the C# reference
+// writes (`CultMeshAuthorityProofTests.AuthorityRouteVectorsAreSharedWithTypeScript`
+// under CULTMESH_WRITE_VECTORS=1); a fixture authored on this side alone would
+// only agree with itself.
+
+import test from "node:test";
+import assert from "node:assert/strict";
+import { generateKeyPairSync, sign, type KeyObject } from "node:crypto";
+import { readFileSync } from "node:fs";
+import { join } from "node:path";
+
+import type { CultMeshSessionOpenMessage } from "../src/contracts";
+import {
+  base64ToBytes,
+  bytesToBase64,
+  canonicalRoute,
+  canonicalSession,
+  isLoopbackEndpoint,
+  isProtectedEndpoint,
+  verifyAuthorityRoute,
+  verifyP256,
+  verifyProviderSessionProof,
+  type CultMeshAuthorityRouteView,
+  type CultMeshP256PublicKey,
+} from "../src/cultmesh-authority";
+
+const NOW = 1_800_000_000_000;
+const VECTORS_PATH = join(__dirname, "..", "..", "..", "..", "contracts", "cultmesh", "authority-route-vectors.json");
+
+interface Vectors {
+  nowUnixMilliseconds: number;
+  odinRoot: CultMeshP256PublicKey;
+  route: CultMeshAuthorityRouteView;
+  sessionProof: {
+    request: CultMeshSessionOpenMessage;
+    providerKeyId: string;
+    providerSignature: string;
+  };
+}
+
+function keyPair(keyId: string): { privateKey: KeyObject; publicKey: CultMeshP256PublicKey } {
+  const pair = generateKeyPairSync("ec", { namedCurve: "P-256" });
+  const jwk = pair.publicKey.export({ format: "jwk" });
+  return {
+    privateKey: pair.privateKey,
+    publicKey: {
+      keyId,
+      x: Buffer.from(jwk.x!, "base64url").toString("base64"),
+      y: Buffer.from(jwk.y!, "base64url").toString("base64"),
+    },
+  };
+}
+
+function signP1363(privateKey: KeyObject, payload: Uint8Array): string {
+  return sign("sha256", payload, { key: privateKey, dsaEncoding: "ieee-p1363" }).toString("base64");
+}
+
+function signedRoute(endpoint = "wss://provider.example/mesh") {
+  const odin = keyPair("odin-root-1");
+  const provider = keyPair("provider-1");
+  const unsigned: CultMeshAuthorityRouteView = {
+    verseId: "sample.counter",
+    authorityRuntimeId: "sample.counter-daemon",
+    endpoint,
+    protocolId: "cultmesh.documents.v1",
+    protocolIds: ["cultmesh.documents.v1"],
+    priority: 0,
+    generation: "signed-generation-1",
+    certificate: {
+      providerKey: provider.publicKey,
+      odinKeyId: odin.publicKey.keyId,
+      issuedAtUnixMilliseconds: NOW - 60_000,
+      expiresAtUnixMilliseconds: NOW + 3_600_000,
+      signature: "",
+    },
+  };
+  const route: CultMeshAuthorityRouteView = {
+    ...unsigned,
+    certificate: { ...unsigned.certificate!, signature: signP1363(odin.privateKey, canonicalRoute(unsigned)) },
+  };
+  return { route, odin, provider };
+}
+
+function request(clientNonce = "nonce-a"): CultMeshSessionOpenMessage {
+  return {
+    schemaVersion: "cultmesh.session_open.v2",
+    messageId: "message-1",
+    sourceRuntimeId: "consumer-1",
+    verseId: "sample.counter",
+    authorityRuntimeId: "sample.counter-daemon",
+    protocolId: "cultmesh.documents.v1",
+    routeGeneration: "signed-generation-1",
+    clientNonce,
+  };
+}
+
+const remoteTrust = (odinRoot: CultMeshP256PublicKey, now: number = NOW) =>
+  ({ mode: "authenticated-remote" as const, odinRoots: [odinRoot], now: () => now });
+
+test("a signed remote route verifies against its Odin root", async () => {
+  const { route, odin } = signedRoute();
+  await verifyAuthorityRoute(route, remoteTrust(odin.publicKey));
+});
+
+test("an unsigned remote route is refused in both trust modes", async () => {
+  const { route } = signedRoute();
+  const unsigned = { ...route, certificate: undefined };
+  await assert.rejects(verifyAuthorityRoute(unsigned, { mode: "authenticated-remote" }), /Odin-signed authority certificate/);
+  await assert.rejects(verifyAuthorityRoute(unsigned, { mode: "local-development" }), /Odin-signed authority certificate/);
+});
+
+test("an unsigned loopback route is accepted only under local-development", async () => {
+  const { route } = signedRoute("ws://127.0.0.1:4050/mesh");
+  const unsigned = { ...route, certificate: undefined };
+  await verifyAuthorityRoute(unsigned, { mode: "local-development" });
+  await assert.rejects(verifyAuthorityRoute(unsigned, { mode: "authenticated-remote" }), /Odin-signed authority certificate/);
+});
+
+test("a certified route on an unprotected scheme is refused unless it is loopback under local-development", async () => {
+  const remote = signedRoute("ws://provider.example/mesh");
+  await assert.rejects(verifyAuthorityRoute(remote.route, remoteTrust(remote.odin.publicKey)), /channel protection/);
+  const loopback = signedRoute("ws://localhost:4050/mesh");
+  await assert.rejects(verifyAuthorityRoute(loopback.route, remoteTrust(loopback.odin.publicKey)), /channel protection/);
+  await verifyAuthorityRoute(loopback.route, { ...remoteTrust(loopback.odin.publicKey), mode: "local-development" });
+});
+
+test("the validity window is half-open: issuedAt inclusive, expiresAt exclusive", async () => {
+  const { route, odin } = signedRoute();
+  const certificate = route.certificate!;
+  await verifyAuthorityRoute(route, remoteTrust(odin.publicKey, certificate.issuedAtUnixMilliseconds));
+  await verifyAuthorityRoute(route, remoteTrust(odin.publicKey, certificate.expiresAtUnixMilliseconds - 1));
+  await assert.rejects(
+    verifyAuthorityRoute(route, remoteTrust(odin.publicKey, certificate.expiresAtUnixMilliseconds)),
+    /not currently valid/,
+  );
+  await assert.rejects(
+    verifyAuthorityRoute(route, remoteTrust(odin.publicKey, certificate.issuedAtUnixMilliseconds - 1)),
+    /not currently valid/,
+  );
+});
+
+test("an Odin root the consumer does not trust is refused before any signature check", async () => {
+  const { route } = signedRoute();
+  const stranger = keyPair("odin-root-1");
+  await assert.rejects(verifyAuthorityRoute(route, { mode: "authenticated-remote", odinRoots: [], now: () => NOW }), /is not trusted/);
+  await assert.rejects(
+    verifyAuthorityRoute(route, { mode: "authenticated-remote", odinRoots: [{ ...stranger.publicKey, keyId: "other-root" }], now: () => NOW }),
+    /is not trusted/,
+  );
+  await assert.rejects(verifyAuthorityRoute(route, remoteTrust(stranger.publicKey)), /signature is invalid/);
+});
+
+test("a mutated endpoint invalidates the Odin signature", async () => {
+  const { route, odin } = signedRoute();
+  await assert.rejects(
+    verifyAuthorityRoute({ ...route, endpoint: "wss://evil.example/mesh" }, remoteTrust(odin.publicKey)),
+    /signature is invalid/,
+  );
+});
+
+test("a signature that is not 64 P1363 bytes is refused", async () => {
+  const { route, odin } = signedRoute();
+  const bytes = base64ToBytes(route.certificate!.signature);
+  for (const wrong of [bytes.subarray(0, 63), new Uint8Array([...bytes, 0])]) {
+    await assert.rejects(
+      verifyAuthorityRoute(
+        { ...route, certificate: { ...route.certificate!, signature: bytesToBase64(wrong) } },
+        remoteTrust(odin.publicKey),
+      ),
+      /signature is invalid/,
+    );
+  }
+  assert.equal(await verifyP256(odin.publicKey, canonicalRoute(route), "not base64!"), false);
+});
+
+test("the provider session proof binds the nonce, the endpoint and the certified key", async () => {
+  const { route, provider } = signedRoute();
+  const open = request();
+  const signature = signP1363(provider.privateKey, canonicalSession(open, route.endpoint));
+  assert.equal(await verifyProviderSessionProof(open, route.endpoint, provider.publicKey, signature), true);
+  assert.equal(await verifyProviderSessionProof(request("nonce-b"), route.endpoint, provider.publicKey, signature), false);
+  assert.equal(await verifyProviderSessionProof(open, "wss://evil.example/mesh", provider.publicKey, signature), false);
+  assert.equal(await verifyProviderSessionProof(open, route.endpoint, keyPair("provider-1").publicKey, signature), false);
+});
+
+test("isProtectedEndpoint is the C# rule: wss, https, or any scheme containing quic", () => {
+  for (const accepted of ["wss://provider.example/mesh", "https://provider.example/content", "cultmesh-state+quic://provider.example:4433"]) {
+    assert.equal(isProtectedEndpoint(accepted), true, accepted);
+  }
+  for (const refused of ["ws://provider.example/mesh", "cultnet+tcp://provider.example:3076", "not a url"]) {
+    assert.equal(isProtectedEndpoint(refused), false, refused);
+  }
+});
+
+test("isLoopbackEndpoint recognises localhost, 127.0.0.1 and ::1 only", () => {
+  for (const loopback of ["ws://localhost:4050/mesh", "ws://127.0.0.1:4050/mesh", "ws://[::1]:4050/mesh", "wss://LOCALHOST/mesh"]) {
+    assert.equal(isLoopbackEndpoint(loopback), true, loopback);
+  }
+  for (const remote of ["ws://192.0.2.10:4050/mesh", "wss://provider.example/mesh", "ws://127.0.0.2/mesh", "not a url"]) {
+    assert.equal(isLoopbackEndpoint(remote), false, remote);
+  }
+});
+
+test("base64 helpers round-trip across the 32 KiB chunk boundary", () => {
+  const bytes = new Uint8Array(70_000).map((_, index) => index % 251);
+  assert.deepEqual(base64ToBytes(bytesToBase64(bytes)), bytes);
+});
+
+test("the C# reference vectors verify through the shared module", async () => {
+  const vectors = JSON.parse(readFileSync(VECTORS_PATH, "utf8")) as Vectors;
+  const trust = { mode: "authenticated-remote" as const, odinRoots: [vectors.odinRoot], now: () => vectors.nowUnixMilliseconds };
+  await verifyAuthorityRoute(vectors.route, trust);
+  await assert.rejects(verifyAuthorityRoute({ ...vectors.route, priority: 8 }, trust), /signature is invalid/);
+  await assert.rejects(
+    verifyAuthorityRoute({ ...vectors.route, protocolIds: [...vectors.route.protocolIds!, "cultmesh.realtime.v1"] }, trust),
+    /signature is invalid/,
+  );
+
+  const proof = vectors.sessionProof;
+  assert.equal(proof.providerKeyId, vectors.route.certificate!.providerKey.keyId);
+  assert.equal(
+    await verifyProviderSessionProof(proof.request, vectors.route.endpoint, vectors.route.certificate!.providerKey, proof.providerSignature),
+    true,
+  );
+  assert.equal(
+    await verifyProviderSessionProof({ ...proof.request, clientNonce: "replayed" }, vectors.route.endpoint, vectors.route.certificate!.providerKey, proof.providerSignature),
+    false,
+  );
+});
+
+test("the shared module keeps the browser-safe surface: no node: import", () => {
+  const source = readFileSync(join(__dirname, "..", "..", "src", "cultmesh-authority.ts"), "utf8");
+  assert.doesNotMatch(source, /from "node:|require\("node:/);
+});
diff --git a/tests/GameCult.Mesh.Tests/CultMeshAuthorityProofTests.cs b/tests/GameCult.Mesh.Tests/CultMeshAuthorityProofTests.cs
index 42f02297..44c078cc 100644
--- a/tests/GameCult.Mesh.Tests/CultMeshAuthorityProofTests.cs
+++ b/tests/GameCult.Mesh.Tests/CultMeshAuthorityProofTests.cs
@@ -1,10 +1,12 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Net;
 using System.Net.Http;
 using System.Security.Cryptography;
 using System.Text;
+using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
 using FluentAssertions;
@@ -225,6 +227,132 @@ public sealed class CultMeshAuthorityProofTests
         handler.RequestUri.Query.Should().Contain("chunkHash=").And.Contain("recordKey=");
     }
 
+    // Shared-vector check with `packages/cultnet-ts/src/cultmesh-authority.ts`.
+    // The C# reference signs a route and a session proof with fixed keys and
+    // writes them when CULTMESH_WRITE_VECTORS=1; otherwise it asserts the
+    // committed file still verifies here. The TypeScript test verifies the same
+    // file, so both runtimes are pinned to the same transcript bytes.
+    [Test]
+    public void AuthorityRouteVectorsAreSharedWithTypeScript()
+    {
+        var path = Path.Combine(RepoRoot(), "contracts", "cultmesh", "authority-route-vectors.json");
+        using var odin = ECDsa.Create();
+        odin.ImportFromPem(VectorOdinPrivateKeyPem);
+        using var provider = ECDsa.Create();
+        provider.ImportFromPem(VectorProviderPrivateKeyPem);
+        var odinPublic = CultMeshEcdsaP256PublicKey.From("odin-vector", odin);
+        var providerPublic = CultMeshEcdsaP256PublicKey.From("provider-vector", provider);
+        var request = new GameCult.Networking.CultMeshSessionOpenMessage
+        {
+            MessageId = "vector-message-1",
+            SourceRuntimeId = "vector-consumer",
+            VerseId = "aetheria",
+            AuthorityRuntimeId = "aetheria-daemon",
+            ProtocolId = CultMeshProtocols.Documents.Value,
+            RouteGeneration = "vector-generation-1",
+            ClientNonce = Convert.ToBase64String(SHA256.HashData(Encoding.UTF8.GetBytes("vector-nonce")))
+        };
+
+        if (Environment.GetEnvironmentVariable("CULTMESH_WRITE_VECTORS") == "1")
+        {
+            var signedRoute = CultMeshAuthorityProof.CreateSignedRoute(
+                "aetheria", "aetheria-daemon", "wss://provider.example/mesh",
+                new[] { CultMeshProtocols.Documents.Value, CultMeshProtocols.Content.Value }, 7, "vector-generation-1",
+                providerPublic, odinPublic.KeyId, Now.AddMinutes(-1), Now.AddHours(1), odin);
+            var signer = new CultMeshSessionProofSigner(signedRoute, provider);
+            Directory.CreateDirectory(Path.GetDirectoryName(path)!);
+            File.WriteAllText(path, JsonSerializer.Serialize(new
+            {
+                nowUnixMilliseconds = Now.ToUnixTimeMilliseconds(),
+                odinRoot = new { keyId = odinPublic.KeyId, x = odinPublic.X, y = odinPublic.Y },
+                route = new
+                {
+                    verseId = "aetheria",
+                    authorityRuntimeId = signedRoute.AuthorityRuntimeId,
+                    endpoint = signedRoute.Endpoint,
+                    protocolIds = signedRoute.ProtocolIds,
+                    priority = signedRoute.Priority,
+                    generation = signedRoute.Generation,
+                    certificate = new
+                    {
+                        providerKey = new { keyId = providerPublic.KeyId, x = providerPublic.X, y = providerPublic.Y },
+                        odinKeyId = signedRoute.Certificate!.OdinKeyId,
+                        issuedAtUnixMilliseconds = signedRoute.Certificate.IssuedAtUnixMilliseconds,
+                        expiresAtUnixMilliseconds = signedRoute.Certificate.ExpiresAtUnixMilliseconds,
+                        signature = signedRoute.Certificate.Signature
+                    }
+                },
+                sessionProof = new
+                {
+                    request = new
+                    {
+                        schemaVersion = request.SchemaVersion,
+                        messageId = request.MessageId,
+                        sourceRuntimeId = request.SourceRuntimeId,
+                        verseId = request.VerseId,
+                        authorityRuntimeId = request.AuthorityRuntimeId,
+                        protocolId = request.ProtocolId,
+                        routeGeneration = request.RouteGeneration,
+                        clientNonce = request.ClientNonce
+                    },
+                    providerKeyId = signer.ProviderKeyId,
+                    providerSignature = signer.Sign(request)
+                }
+            }, new JsonSerializerOptions
+            {
+                WriteIndented = true,
+                Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping
+            }) + "\n");
+        }
+
+        using var vectors = JsonDocument.Parse(File.ReadAllText(path));
+        var rootElement = vectors.RootElement;
+        var routeElement = rootElement.GetProperty("route");
+        var certificateElement = routeElement.GetProperty("certificate");
+        var route = new CultMeshAuthorityRoute(
+            routeElement.GetProperty("authorityRuntimeId").GetString()!,
+            routeElement.GetProperty("endpoint").GetString()!,
+            routeElement.GetProperty("protocolIds").EnumerateArray().Select(value => value.GetString()!).ToArray(),
+            routeElement.GetProperty("priority").GetInt32(),
+            routeElement.GetProperty("generation").GetString(),
+            new CultMeshRouteCertificate(
+                providerPublic,
+                certificateElement.GetProperty("odinKeyId").GetString()!,
+                certificateElement.GetProperty("issuedAtUnixMilliseconds").GetInt64(),
+                certificateElement.GetProperty("expiresAtUnixMilliseconds").GetInt64(),
+                certificateElement.GetProperty("signature").GetString()!));
+        var trust = new CultMeshAuthorityTrustPolicy(CultMeshAuthorityTrustMode.AuthenticatedRemote, new[] { odinPublic });
+        var now = DateTimeOffset.FromUnixTimeMilliseconds(rootElement.GetProperty("nowUnixMilliseconds").GetInt64());
+        var verseId = routeElement.GetProperty("verseId").GetString()!;
+
+        trust.Validate(verseId, route, now);
+        var proofElement = rootElement.GetProperty("sessionProof");
+        var accepted = Accepted(request, proofElement.GetProperty("providerSignature").GetString()!);
+        accepted.ProviderKeyId = proofElement.GetProperty("providerKeyId").GetString()!;
+        CultMeshAuthorityProof.VerifySessionProof(request, accepted, verseId, route, trust, now).Should().BeTrue();
+    }
+
+    private static string RepoRoot()
+    {
+        var directory = new DirectoryInfo(TestContext.CurrentContext.TestDirectory);
+        while (directory != null && !File.Exists(Path.Combine(directory.FullName, "CultLib.sln")))
+            directory = directory.Parent;
+        return directory?.FullName ?? throw new InvalidOperationException("CultLib.sln was not found above the test directory.");
+    }
+
+    // Fixed test keys. They sign only the committed vector and prove nothing else.
+    private const string VectorOdinPrivateKeyPem = @"-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgHY0//QOheSwARzXE
+iX/nGqSD7XFAy530QQqKeXPNxMChRANCAASyEksa2ZGtboPztVAq/TFhB6Qsh8SR
+43t1VrDCmYgpY4kehsd2lQoIc0sqO06l6q/td/ey+9ygzWbszdnGeeSB
+-----END PRIVATE KEY-----";
+
+    private const string VectorProviderPrivateKeyPem = @"-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgVC+9X4t+1HAiIxP4
+TEuAuBAY+3ryKK8SaitB0TqsPQqhRANCAATpci+DHdbWruUkURXTJht4pY0WCyyr
+ngEcG6H2ALBwf6ItRYiq2rni4nPlXpszsdfDDcBurYZmTFFnqjcOrzTp
+-----END PRIVATE KEY-----";
+
     private static CultMeshAuthorityRoute SignedRoute(ECDsa odin, ECDsa provider) =>
         CultMeshAuthorityProof.CreateSignedRoute(
             "aetheria",