V48 Gate 3 (implementation-only): deposit host selection — InlineHost (dev) / VercelSandboxHost (prod)

Closes the prod-host loose end: resolveDepositPipelineHost now selects the Host implementation. selectDepositHostKind (pure, tested) honors an explicit BITCODE_PIPELINE_HOST, else routes a Vercel serverless runtime (no git/FS) to the sandbox host and a local/dev runtime to the in-process InlineHost. The sandbox path constructs VercelSandboxHost via loadVercelSandboxFactory() (the @vercel/sandbox SDK) with Vercel auth (OIDC-preferred, else access token). resolveDepositPipelineHost is now async; the route awaits it.

Both implement the same primitive, so provisioning is identical downstream: the host clones the full checkout, readWorkspaceSources materializes the verbatim source into the inventory, and measurement reads it — on either host.

selectDepositHostKind unit tests (explicit override, Vercel→sandbox, local→inline); provisioning + route suites 8/8; tsc clean. Prod deposit now rides the sandbox host (its infra — @vercel/sandbox + VERCEL_* creds + git in the sandbox image — is deployment config). Known follow-on: the sandbox workspace reads files per-call (readFileToBuffer); batch via tar for large repos.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: geraldarthurdavis

uapi/app/api/deposit/synthesize-options/route.ts

@@ -207,7 +207,7 @@ export async function POST(request: Request) {
     // in-process; the Vercel Sandbox host in prod). The static-analysis measurement
     // reads the real full source (inventory.sources); bounded samples feed the
     // prompts. This is the host's job — the dispatching request does not clone.
-    const host = resolveDepositPipelineHost();
+    const host = await resolveDepositPipelineHost();
     await emitStatus(
       `Provisioning ${repositoryFullName}@${reference} on the ${host.capabilities.hostKind} host…`,
     );

uapi/lib/deposit-source-provisioning.ts

@@ -16,6 +16,8 @@
 
 import {
   InlineHost,
+  VercelSandboxHost,
+  loadVercelSandboxFactory,
   readWorkspaceSources,
   type BitcodePipelineHost,
   type HostSourceFile,
@@ -58,12 +60,46 @@ function pickSamples(sources: HostSourceFile[]): { path: string; excerpt: string
     .map((path) => ({ path, excerpt: (byPath.get(path) || '').slice(0, MAX_SAMPLE_CHARS) }));
 }
 
+export type DepositHostKind = 'inline' | 'vercel-sandbox';
+
+/**
+ * Select the deposit Host kind. Explicit `BITCODE_PIPELINE_HOST` wins; otherwise a
+ * Vercel serverless runtime (no git binary / ephemeral FS) MUST use the sandbox host,
+ * while a local/dev runtime (the persistent Node server has git + a filesystem) uses
+ * the in-process InlineHost. Pure + testable.
+ */
+export function selectDepositHostKind(env: NodeJS.ProcessEnv = process.env): DepositHostKind {
+  const explicit = env.BITCODE_PIPELINE_HOST?.trim().toLowerCase();
+  if (explicit === 'inline' || explicit === 'vercel-sandbox') return explicit;
+  return env.VERCEL ? 'vercel-sandbox' : 'inline';
+}
+
+/** Vercel auth for sandbox creation: prefer OIDC; otherwise pass the access token. */
+function vercelSandboxCreateOptions() {
+  if (process.env.VERCEL_OIDC_TOKEN) return {};
+  return {
+    token: process.env.VERCEL_TOKEN,
+    teamId: process.env.VERCEL_TEAM_ID,
+    projectId: process.env.VERCEL_PROJECT_ID,
+  };
+}
+
 /**
- * Resolve the deposit pipeline Host. In-process (InlineHost) today; the Vercel
- * Sandbox host in prod once wired. The deposit run is the harness run, so the host
- * provisions the source — the dispatching request does not.
+ * Resolve the deposit pipeline Host. The deposit run is the harness run, so the Host
+ * provisions the source — the dispatching request does not. InlineHost runs in-process
+ * (dev); VercelSandboxHost provisions a durable sandbox (prod) because a serverless
+ * function cannot clone. Both implement the same primitive, so provisioning is
+ * identical downstream.
  */
-export function resolveDepositPipelineHost(): BitcodePipelineHost {
+export async function resolveDepositPipelineHost(): Promise<BitcodePipelineHost> {
+  if (selectDepositHostKind() === 'vercel-sandbox') {
+    const sandboxFactory = await loadVercelSandboxFactory();
+    return new VercelSandboxHost({
+      sandboxFactory,
+      runtime: 'node22',
+      createOptions: vercelSandboxCreateOptions(),
+    });
+  }
   return new InlineHost();
 }
 

uapi/tests/lib/depositSourceProvisioning.test.ts

@@ -1,7 +1,10 @@
 /**
  * @jest-environment node
  */
-import { provisionDepositSourceInventory } from '@/lib/deposit-source-provisioning';
+import {
+  provisionDepositSourceInventory,
+  selectDepositHostKind,
+} from '@/lib/deposit-source-provisioning';
 import type { BitcodeHostWorkspace, BitcodePipelineHost } from '@bitcode/pipeline-hosts';
 
 const FILES: Record<string, string> = {
@@ -75,3 +78,16 @@ describe('provisionDepositSourceInventory', () => {
     expect(isDisposed()).toBe(true);
   });
 });
+
+describe('selectDepositHostKind', () => {
+  it('honors an explicit BITCODE_PIPELINE_HOST', () => {
+    expect(selectDepositHostKind({ BITCODE_PIPELINE_HOST: 'inline' } as any)).toBe('inline');
+    expect(selectDepositHostKind({ BITCODE_PIPELINE_HOST: 'vercel-sandbox' } as any)).toBe('vercel-sandbox');
+    expect(selectDepositHostKind({ BITCODE_PIPELINE_HOST: ' Vercel-Sandbox ' } as any)).toBe('vercel-sandbox');
+  });
+
+  it('uses the sandbox on Vercel (no git/FS) and inline locally', () => {
+    expect(selectDepositHostKind({ VERCEL: '1' } as any)).toBe('vercel-sandbox');
+    expect(selectDepositHostKind({} as any)).toBe('inline');
+  });
+});