release(v4.0.0): Shade GA — V3.x consolidation + audit prep

V3.1 → V3.12 consolidated and tagged for the first GA release. Wire
format unchanged from 0.4.x — 4.0 peers interoperate with 0.4.x peers
byte-for-byte. The version bump is semantic: audit-cycle complete,
opt-in surface fully exposed, threat model refreshed for every new
surface.

Highlights:
- All 24 @shade/* packages bumped to 4.0.0 in lockstep.
- CHANGELOG 4.0.0 section is the canonical manifest of what landed.
- THREAT-MODEL extended (§10 fingerprint gates, §11 WebRTC P2P, §12
  Web-Worker boundary) + residual-risks table refreshed.
- OpenAPI now covers all 27 routes: prekey, transfer, KT, inbox,
  bridge, observer, /metrics, /healthz, /ready.
- MIGRATION 0.3.x → 4.0 documented + smoke-tested against
  shade migrate-storage on a real SQLite DB.
- docs/audit/REVIEW-BUNDLE.md + SCOPE.md ready for external reviewer.
- scripts/soak.ts harness for the GA-stable 2-week soak window.
- All V*.md plans archived under docs/archive/ with Status: Done.
- Voice/Video carved out into V5.0; 4.0 audit focuses on the frozen
  non-realtime stack.

Tests: TS 1000/1000 + Kotlin 11/11 cross-platform vectors green.
Docker: gt.zyon.no/stian/shade-prekey:4.0.0 builds and reports
  version 4.0.0 on /health.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shade-key-transparency/tests/witness.test.ts

@@ -0,0 +1,223 @@
+import { describe, expect, test } from 'bun:test';
+import { SubtleCryptoProvider } from '@shade/crypto-web';
+import {
+  KTLogManager,
+  LightWitness,
+  MemoryKTLogStore,
+  computeBundleHash,
+  computeLogId,
+  signSth,
+  sthToWire,
+} from '../src/index.js';
+import {
+  KTLogIdMismatchError,
+  KTSplitViewError,
+  KTStaleSTHError,
+  KTVerificationError,
+} from '../src/errors.js';
+import { toBase64, fromBase64 } from '../src/util.js';
+
+const crypto = new SubtleCryptoProvider();
+
+async function setup() {
+  const kp = await crypto.generateEd25519KeyPair();
+  const store = new MemoryKTLogStore();
+  const mgr = await KTLogManager.create({
+    crypto,
+    store,
+    signingPrivateKey: kp.privateKey,
+    signingPublicKey: kp.publicKey,
+  });
+  return { kp, mgr };
+}
+
+function fakeBundle(seed: number) {
+  return {
+    identitySigningKey: new Uint8Array(32).fill(seed),
+    identityDHKey: new Uint8Array(32).fill(seed + 1),
+    signedPreKey: {
+      keyId: 1,
+      publicKey: new Uint8Array(32).fill(seed + 2),
+      signature: new Uint8Array(64).fill(seed + 3),
+    },
+  };
+}
+
+describe('LightWitness', () => {
+  test('observes valid STH and stores it', async () => {
+    const { kp, mgr } = await setup();
+    await mgr.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sth = await mgr.publishSTH();
+
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: kp.publicKey,
+      fetcher: {
+        async fetchLatestSTH() {
+          return sthToWire(sth, toBase64);
+        },
+        async fetchConsistencyProof() {
+          return { proof: [] };
+        },
+      },
+    });
+    const polled = await witness.pollOnce();
+    expect(polled.treeSize).toBe(1);
+    expect(witness.compare(sth)).toBe('agree');
+  });
+
+  test('rejects STH whose log_id does not match pinned key', async () => {
+    const { mgr } = await setup();
+    const wrong = await crypto.generateEd25519KeyPair();
+    await mgr.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sth = await mgr.publishSTH();
+
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: wrong.publicKey, // pinned to wrong key
+      fetcher: {
+        async fetchLatestSTH() {
+          return sthToWire(sth, toBase64);
+        },
+        async fetchConsistencyProof() {
+          return { proof: [] };
+        },
+      },
+    });
+    await expect(witness.pollOnce()).rejects.toBeInstanceOf(KTLogIdMismatchError);
+  });
+
+  test('rejects STH older than maxStaleMs', async () => {
+    const { kp, mgr } = await setup();
+    await mgr.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sth = await mgr.publishSTH(1000); // far in the past
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: kp.publicKey,
+      fetcher: {
+        async fetchLatestSTH() {
+          return sthToWire(sth, toBase64);
+        },
+        async fetchConsistencyProof() {
+          return { proof: [] };
+        },
+      },
+      maxStaleMs: 1000,
+      now: () => 10_000_000,
+    });
+    await expect(witness.pollOnce()).rejects.toBeInstanceOf(KTStaleSTHError);
+  });
+
+  test('detects split-view at same tree_size', async () => {
+    const { kp, mgr } = await setup();
+    await mgr.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sth1 = await mgr.publishSTH();
+
+    // Forge another signed STH with same tree_size but different rootHash
+    const tamperedRoot = new Uint8Array(sth1.rootHash);
+    tamperedRoot[0] ^= 0xff;
+    const sth2 = await signSth(crypto, kp.privateKey, {
+      treeSize: sth1.treeSize,
+      timestampMs: sth1.timestampMs,
+      rootHash: tamperedRoot,
+      indexRoot: sth1.indexRoot,
+      logId: computeLogId(kp.publicKey),
+    });
+
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: kp.publicKey,
+      fetcher: {
+        async fetchLatestSTH() {
+          return sthToWire(sth1, toBase64);
+        },
+        async fetchConsistencyProof() {
+          return { proof: [] };
+        },
+      },
+    });
+    await witness.observe(sth1);
+    await expect(witness.observe(sth2)).rejects.toBeInstanceOf(KTSplitViewError);
+  });
+
+  test('verifies consistency between two successive STHs', async () => {
+    const { kp, mgr } = await setup();
+    await mgr.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sth1 = await mgr.publishSTH();
+    await mgr.recordRegister('bob', computeBundleHash(fakeBundle(0x20)));
+    const sth2 = await mgr.publishSTH();
+
+    const consistency = await mgr.buildConsistencyProof(sth1.treeSize);
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: kp.publicKey,
+      fetcher: {
+        async fetchLatestSTH() {
+          return sthToWire(sth2, toBase64);
+        },
+        async fetchConsistencyProof() {
+          return { proof: consistency.proof.map(toBase64) };
+        },
+      },
+    });
+    await witness.observe(sth1);
+    await witness.observe(sth2);
+    expect(witness.compare(sth2)).toBe('agree');
+  });
+
+  test('rejects STH where log re-wrote history (consistency proof fails)', async () => {
+    const { kp, mgr } = await setup();
+    await mgr.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sth1 = await mgr.publishSTH();
+
+    // Build a forked log where leaf 0 is different.
+    const forkStore = new MemoryKTLogStore();
+    const forkMgr = await KTLogManager.create({
+      crypto,
+      store: forkStore,
+      signingPrivateKey: kp.privateKey,
+      signingPublicKey: kp.publicKey,
+    });
+    await forkMgr.recordRegister('mallory', computeBundleHash(fakeBundle(0xee)));
+    await forkMgr.recordRegister('bob', computeBundleHash(fakeBundle(0x20)));
+    const forkedSth2 = await forkMgr.publishSTH();
+    const forkedConsistency = await forkMgr.buildConsistencyProof(sth1.treeSize);
+
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: kp.publicKey,
+      fetcher: {
+        async fetchLatestSTH() {
+          return sthToWire(forkedSth2, toBase64);
+        },
+        async fetchConsistencyProof() {
+          return { proof: forkedConsistency.proof.map(toBase64) };
+        },
+      },
+    });
+    await witness.observe(sth1);
+    await expect(witness.observe(forkedSth2)).rejects.toBeInstanceOf(KTVerificationError);
+  });
+
+  test('compare returns "unknown" for tree_size we have not seen', async () => {
+    const { kp, mgr } = await setup();
+    await mgr.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sth = await mgr.publishSTH();
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: kp.publicKey,
+      fetcher: {
+        async fetchLatestSTH() {
+          return sthToWire(sth, toBase64);
+        },
+        async fetchConsistencyProof() {
+          return { proof: [] };
+        },
+      },
+    });
+    expect(witness.compare(sth)).toBe('unknown');
+  });
+});
+
+// Make TS happy about unused fromBase64
+void fromBase64;