diff --git a/TODO.md b/TODO.md
index 98e472b..794ba60 100644
--- a/TODO.md
+++ b/TODO.md
@@ -139,8 +139,8 @@ These items **must** be completed to have a usable system. Without them, users c
   - Link pages via `prevPageId`/`nextPageId`
   - Initialise `PageActivity` records with zero counts
 
-- [ ] **P0-C2:** Implement `hippocampus/Ingest.ts` (minimal version)
-  - Entry point: `ingestText(text, modelProfile, vectorStore, metadataStore, keyPair)`
+- [x] **P0-C2:** Implement `hippocampus/Ingest.ts` (minimal version)
+  - Entry point: `ingestText(text, { modelProfile, embeddingRunner, vectorStore, metadataStore, keyPair, ... })`
   - Chunk text via `Chunker`
   - Batch embed chunks via `EmbeddingRunner`
   - Persist vectors to `VectorStore`
diff --git a/hippocampus/Ingest.ts b/hippocampus/Ingest.ts
index 0f3fba2..e8257bf 100644
--- a/hippocampus/Ingest.ts
+++ b/hippocampus/Ingest.ts
@@ -1,4 +1,5 @@
-import type { Book, ModelProfile, MetadataStore, VectorStore } from "../core/types";
+import type { Book, MetadataStore, VectorStore } from "../core/types";
+import type { ModelProfile } from "../core/ModelProfile";
 import { hashText } from "../core/crypto/hash";
 import type { KeyPair } from "../core/crypto/sign";
 import { EmbeddingRunner } from "../embeddings/EmbeddingRunner";
diff --git a/hippocampus/PageBuilder.ts b/hippocampus/PageBuilder.ts
index cd79464..d03e9e3 100644
--- a/hippocampus/PageBuilder.ts
+++ b/hippocampus/PageBuilder.ts
@@ -1,5 +1,4 @@
 import type { Hash, Page } from "../core/types";
-import type { KeyPair } from "../core/crypto/sign";
 import { hashBinary, hashText } from "../core/crypto/hash";
 import { signData } from "../core/crypto/sign";
 
@@ -43,10 +42,10 @@ export async function buildPage(options: BuildPageOptions): Promise<Page> {
   const contentHash = await hashText(content);
   const pageId = contentHash;
 
-  const rawVector = embedding.buffer.slice(
-    embedding.byteOffset,
-    embedding.byteOffset + embedding.byteLength,
-  );
+  // Copy into a new ArrayBuffer-backed view so we never pass a SharedArrayBuffer
+  // into WebCrypto (and keep TypeScript happy).
+  const rawVector = new Uint8Array(embedding.byteLength);
+  rawVector.set(new Uint8Array(embedding.buffer, embedding.byteOffset, embedding.byteLength));
   const vectorHash = await hashBinary(rawVector);
 
   const unsignedPage = {
diff --git a/tests/hippocampus/PageBuilder.test.ts b/tests/hippocampus/PageBuilder.test.ts
index 3498f6a..5559b9a 100644
--- a/tests/hippocampus/PageBuilder.test.ts
+++ b/tests/hippocampus/PageBuilder.test.ts
@@ -6,7 +6,7 @@ import { generateKeyPair } from "../../core/crypto/sign";
 import { verifySignature } from "../../core/crypto/verify";
 import { hashBinary, hashText } from "../../core/crypto/hash";
 
-function canonicalizePageForSigning(page: Omit<Page, "signature">) {
+function canonicalizePageForSigning(page: Page) {
   return JSON.stringify({
     pageId: page.pageId,
     content: page.content,
@@ -44,9 +44,10 @@ describe("buildPage", () => {
     expect(page.pageId).toBe(expectedContentHash);
     expect(page.contentHash).toBe(expectedContentHash);
 
-    const rawVector = embedding.buffer.slice(
+    const rawVector = new Uint8Array(
+      embedding.buffer,
       embedding.byteOffset,
-      embedding.byteOffset + embedding.byteLength,
+      embedding.byteLength,
     );
     const expectedVectorHash = await hashBinary(rawVector);
     expect(page.vectorHash).toBe(expectedVectorHash);