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-transport/tests/kt-split-view-e2e.test.ts

@@ -0,0 +1,176 @@
+/**
+ * Acceptance test for V3.12 §"End-to-end test: split-view detection".
+ *
+ * Scenario:
+ *   - One legitimate STH-signing key (the operator's pinned key).
+ *   - Two divergent log views A and B, both signed by the same key
+ *     (simulating a malicious server that hands different responses to
+ *     different clients).
+ *   - Two clients (Bob, Charlie) each fetch alice's bundle, but each is
+ *     served from a different view.
+ *   - A `LightWitness` cross-pollinates the two clients' STHs.
+ *   - The witness must reject the second STH at the same tree_size with
+ *     a `KTSplitViewError`.
+ *
+ * Also asserts the *positive* path: when both clients see the same view,
+ * no error is raised.
+ */
+
+import { describe, expect, test } from 'bun:test';
+import { SubtleCryptoProvider } from '@shade/crypto-web';
+import {
+  KTLogManager,
+  KTSplitViewError,
+  LightWitness,
+  MemoryKTLogStore,
+  computeBundleHash,
+  computeLogId,
+} from '@shade/key-transparency';
+
+const crypto = new SubtleCryptoProvider();
+
+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('Split-view E2E', () => {
+  test('two divergent views at the same tree_size are caught by witness', async () => {
+    const operator = await crypto.generateEd25519KeyPair();
+
+    // View A — alice has the *real* identity (seed 0x10)
+    const viewA = await KTLogManager.create({
+      crypto,
+      store: new MemoryKTLogStore(),
+      signingPrivateKey: operator.privateKey,
+      signingPublicKey: operator.publicKey,
+    });
+    await viewA.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sthA = await viewA.publishSTH();
+
+    // View B — alice has a *malicious* identity (seed 0xff)
+    const viewB = await KTLogManager.create({
+      crypto,
+      store: new MemoryKTLogStore(),
+      signingPrivateKey: operator.privateKey,
+      signingPublicKey: operator.publicKey,
+    });
+    await viewB.recordRegister('alice', computeBundleHash(fakeBundle(0xff)));
+    const sthB = await viewB.publishSTH();
+
+    // Both STHs claim tree_size = 1 with the same logId, but with
+    // different rootHash + indexRoot. This is what a split-view attack
+    // looks like on the wire.
+    expect(sthA.treeSize).toBe(sthB.treeSize);
+    expect(Buffer.from(sthA.logId).toString('hex')).toBe(
+      Buffer.from(sthB.logId).toString('hex'),
+    );
+    expect(Buffer.from(sthA.rootHash).toString('hex')).not.toBe(
+      Buffer.from(sthB.rootHash).toString('hex'),
+    );
+
+    // Bob has been served STH A; Charlie has been served STH B.
+    // They share a witness (gossip-style):
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: operator.publicKey,
+      fetcher: {
+        async fetchLatestSTH() {
+          throw new Error('not used in this test');
+        },
+        async fetchConsistencyProof() {
+          return { proof: [] };
+        },
+      },
+    });
+
+    await witness.observe(sthA);
+    expect(witness.compare(sthA)).toBe('agree');
+    expect(witness.compare(sthB)).toBe('split-view');
+    await expect(witness.observe(sthB)).rejects.toBeInstanceOf(KTSplitViewError);
+  });
+
+  test('positive path: same view → no false alarm', async () => {
+    const operator = await crypto.generateEd25519KeyPair();
+    const view = await KTLogManager.create({
+      crypto,
+      store: new MemoryKTLogStore(),
+      signingPrivateKey: operator.privateKey,
+      signingPublicKey: operator.publicKey,
+    });
+    await view.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sth1 = await view.publishSTH();
+    await view.recordRegister('bob', computeBundleHash(fakeBundle(0x20)));
+    const sth2 = await view.publishSTH();
+
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: operator.publicKey,
+      fetcher: {
+        async fetchLatestSTH() {
+          throw new Error('not used');
+        },
+        async fetchConsistencyProof(from, to) {
+          const result = await view.buildHistoricalConsistencyProof(from, to);
+          return { proof: result.map((b) => Buffer.from(b).toString('base64')) };
+        },
+      },
+    });
+    await witness.observe(sth1);
+    await witness.observe(sth2);
+    expect(witness.compare(sth2)).toBe('agree');
+  });
+
+  test('rewriting history (forked log at tree_size 1) fails consistency from sth1 → sth2', async () => {
+    const operator = await crypto.generateEd25519KeyPair();
+    const real = await KTLogManager.create({
+      crypto,
+      store: new MemoryKTLogStore(),
+      signingPrivateKey: operator.privateKey,
+      signingPublicKey: operator.publicKey,
+    });
+    await real.recordRegister('alice', computeBundleHash(fakeBundle(0x10)));
+    const sth1 = await real.publishSTH();
+
+    // Build a divergent log that pretends 'mallory' was the first leaf,
+    // not 'alice'. The forked tree's STH at size 2 must NOT pass a
+    // consistency proof against sth1.
+    const fork = await KTLogManager.create({
+      crypto,
+      store: new MemoryKTLogStore(),
+      signingPrivateKey: operator.privateKey,
+      signingPublicKey: operator.publicKey,
+    });
+    await fork.recordRegister('mallory', computeBundleHash(fakeBundle(0xee)));
+    await fork.recordRegister('bob', computeBundleHash(fakeBundle(0x20)));
+    const forkedSth2 = await fork.publishSTH();
+    const forkedConsistency = await fork.buildConsistencyProof(sth1.treeSize);
+
+    const witness = new LightWitness({
+      crypto,
+      logPublicKey: operator.publicKey,
+      fetcher: {
+        async fetchLatestSTH() {
+          throw new Error('not used');
+        },
+        async fetchConsistencyProof() {
+          return { proof: forkedConsistency.proof.map((b) => Buffer.from(b).toString('base64')) };
+        },
+      },
+    });
+    await witness.observe(sth1);
+    await expect(witness.observe(forkedSth2)).rejects.toThrow();
+
+    // sanity: logId pinning still valid
+    expect(Buffer.from(forkedSth2.logId).toString('hex')).toBe(
+      Buffer.from(computeLogId(operator.publicKey)).toString('hex'),
+    );
+  });
+});