fix(sandbox): PR-B fold-ins — allow read ~/.claude + skip wrap under test mock

Live PI231 verification of d0dcd28 surfaced two real-runtime issues:

1. ~/.claude was denyRead, but claude CLI MUST read its own OAuth
   credentials file to authenticate. Result: 100% of anthropic requests
   on sandboxed PI231 failed with "Not logged in · Please run /login".
   Live transcript:
     {"event":"fallback_hop_error", "provider":"anthropic",
      "error":"Not logged in · Please run /login"}

   The cross-tenant risk for ~/.claude was a false security trade-off:
   (a) ~/.claude is the spawn's OWN auth, not cross-tenant material
       (all OLP clients share the same Anthropic OAuth — the file is
       not multi-tenant secret)
   (b) Real protection for the model accidentally exfiltrating creds
       via tool_use is Phase 6c's --system-prompt suppressing tool
       descriptions; sandbox-runtime can only blanket-deny a path, not
       distinguish "claude reads creds" from "model emits Read tool"
   Fix: remove ~/.claude from denyRead. Keep ~/.olp, ~/.ssh, ~/.config,
   ~/.codex (all genuinely cross-tenant).
   Suite 44a (cat ~/.olp/keys.json MUST fail) unchanged — still proves
   the core acceptance.
   Suite 44c added (regression guard): in-sandbox cat ~/.claude/.credentials.json
   MUST succeed when the file exists.

2. anthropic.mjs::_spawnAndStream called wrapSpawn() unconditionally,
   including when a test had set __setSpawnImpl(mockFn). The wrap
   rewrites bin to '/bin/sh -c <wrapped-string>' which breaks every HTTP
   integration test that asserts on spawn args. Result on PI231 (sandbox
   active): 16 production-shape tests failed because their mocks were
   never called with the expected bin/args.
   Fix: skip wrapSpawn when spawnImpl !== defaultSpawn (mock active).
   Mocks don't exec, so isolation is meaningless there anyway. Real-CLI
   spawns (production + Suite 44) still get wrapped.

Tests: 813 → 813 (44c is also PI231-gated, skips on Mac with file
absent; the fold-in does not change Mac test count).

Authority:
- @anthropic-ai/sandbox-runtime v0.0.52 — wrapWithSandbox() shell-string
  return shape is the proximate cause of (2)
- Live PI231 2026-05-28 transcript: /v1/chat/completions returning
  content=null + "Not logged in" from anthropic; OLP_E2E_SANDBOX=1 npm
  test showing 16 prior pass tests now fail
- ADR 0014 § 4.1 PR-B acceptance criteria — the negative test (44a)
  continues to pass; the false-positive denyRead (~/.claude) is corrected

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/providers/anthropic.mjs

@@ -928,15 +928,26 @@ async function* _spawnAndStream(irRequest, authContext, spawnImpl) {
   // ADR 0009 Amendment 1 § unchanged spawn args: only the spawn execution is
   // wrapped — bin/args/env/NDJSON parsing are all unchanged from pre-PR-B.
   //
+  // 2026-05-28 PR-B fold-in: skip sandbox wrap when a custom spawnImpl is in
+  // use (test mode — __setSpawnImpl was called). Test mocks do not actually
+  // exec a binary, so sandbox isolation provides no protection there; the
+  // wrap only obscures the original bin/args from the mock's assertions and
+  // breaks every HTTP integration test that uses __setSpawnImpl + asserts
+  // on spawn args. wrapSpawn is for real-CLI spawns; Suite 44 exercises that
+  // path directly without going through this provider.
+  //
   // Authority: @anthropic-ai/sandbox-runtime v0.0.52 wrapWithSandbox() API,
   //   ADR 0014 § PR-B, spike-anthropic.mjs (PI231 2026-05-28).
-  const wrapped = await wrapSpawn({
-    bin,
-    args,
-    env,
-    cwd: undefined, // let manager assign ephemeral cwd
-    allowedDomains: ['api.anthropic.com', 'statsig.anthropic.com'],
-  });
+  const usingMockSpawn = spawnImpl !== defaultSpawn;
+  const wrapped = usingMockSpawn
+    ? { bin, args, env, cwd: undefined, sandboxed: false }
+    : await wrapSpawn({
+        bin,
+        args,
+        env,
+        cwd: undefined, // let manager assign ephemeral cwd
+        allowedDomains: ['api.anthropic.com', 'statsig.anthropic.com'],
+      });
 
   // OCP server.mjs:542: spawn(CLAUDE, cliArgs, { env, stdio: ["pipe", "pipe", "pipe"] })
   const proc = spawnImpl(wrapped.bin, wrapped.args, {

lib/sandbox/manager.mjs

@@ -167,12 +167,30 @@ export async function bootstrapSandbox(opts = {}) {
   // denyRead: Absolute literal Linux paths per ADR 0014 § Pitfalls #2.
   // No ~ or glob — ripgrep glob expansion is not used here to stay safe on
   // both Linux (bwrap) and macOS (sandbox-exec profile).
+  //
+  // 2026-05-28 PR-B fold-in: ~/.claude is NOT in denyRead. It contains the
+  // spawn's own OAuth credentials — claude CLI must read its own auth file
+  // to function. Denying read here causes "Not logged in" failures even
+  // though the operator has valid credentials present.
+  //
+  // The cross-tenant risk for ~/.claude is mitigated by Phase 6c's
+  // --system-prompt flag (ADR 0009 Amendment 1): the system prompt is
+  // fully replaced, suppressing the default tool descriptions that would
+  // otherwise tell the model it has Read/Bash. Without tool descriptions,
+  // the model is highly unlikely to emit tool_use even under prompt
+  // injection. Sandbox's contribution here is protecting OTHER auth
+  // material (other clients' OLP keys, SSH identity, other providers'
+  // tokens) — files claude CLI does NOT legitimately need.
+  //
+  // If we ever switch to a CLI that requires reading credentials.json
+  // AND also legitimately offers tool execution that surfaces those files
+  // (no known case today), this trade-off needs revisiting.
   const denyRead = [
-    join(home, '.olp'),       // OLP API keys + config
-    join(home, '.claude'),    // Claude OAuth credentials
-    join(home, '.ssh'),       // SSH identity material
+    join(home, '.olp'),       // OLP API keys + config — cross-tenant
+    join(home, '.ssh'),       // SSH identity material — lateral movement
     join(home, '.config'),    // Generic config dir (may contain tokens)
-    join(home, '.codex'),     // Codex config (PR-C will wrap codex)
+    join(home, '.codex'),     // Codex config — other-provider auth (PR-C will wrap codex)
+    // NOT denied: ~/.claude — this spawn's own auth, breaks claude CLI if denied
   ];
 
   // allowWrite: ephemeral spawn workspace only. mkdirSync at bootstrap.

test-features.mjs

@@ -18222,6 +18222,11 @@ describe('Suite 43 — Phase 7 PR-B: lib/sandbox/manager.mjs', () => {
 
 const _RUN_SANDBOX_E2E = Boolean(process.env.OLP_E2E_SANDBOX);
 
+// Suite 44c (fold-in 2026-05-28) needs `join`. statSync already imported at
+// the Suite 17 boundary above. We just need a local `join` alias here since
+// the file-top `join` was bound as `_pathJoinForSetup`.
+const join = _pathJoinForSetup;
+
 describe('Suite 44 — sandbox negative security test (PI231 only)', { skip: !_RUN_SANDBOX_E2E }, () => {
 
   before(async () => {
@@ -18325,4 +18330,48 @@ describe('Suite 44 — sandbox negative security test (PI231 only)', { skip: !_R
     assert.ok(stdout.includes('SANDBOX_PROOF'),
       `stdout must contain SANDBOX_PROOF; got: ${stdout.slice(0, 100)}`);
   });
+
+  it('44c: in-sandbox spawn CAN read ~/.claude/.credentials.json (regression guard for fold-in 2026-05-28)', async () => {
+    // Phase 7 PR-B fold-in (commit pending): ~/.claude removed from denyRead.
+    // The spawn's own OAuth file MUST be readable, otherwise claude CLI fails
+    // with "Not logged in" — and live PI231 verification produces empty
+    // response bodies via the anthropic fallback path.
+    //
+    // The cross-tenant protection for ~/.claude relies on Phase 6c
+    // --system-prompt suppressing tool descriptions, not on sandbox denyRead.
+    // See manager.mjs comment block above denyRead for full rationale.
+    const { spawn: realSpawn } = await import('node:child_process');
+    const credPath = join(homedir(), '.claude', '.credentials.json');
+
+    // If the credentials file isn't present (e.g. dev machine without OAuth),
+    // this test is meaningless — skip the assertion but log.
+    let credStat;
+    try { credStat = statSync(credPath); } catch { credStat = null; }
+    if (!credStat) {
+      // No OAuth file present; cannot test read. Pass with note.
+      assert.ok(true, `No ${credPath} on this host — skipping read-allowed verification`);
+      return;
+    }
+
+    const wrapped = await wrapSpawn({
+      bin: 'cat',
+      args: [credPath],
+      env: { ...process.env },
+      cwd: undefined,
+      allowedDomains: [],
+    });
+
+    const { exitCode } = await new Promise((resolve) => {
+      const child = realSpawn(wrapped.bin, wrapped.args, {
+        env: wrapped.env,
+        cwd: wrapped.cwd,
+        stdio: ['ignore', 'pipe', 'pipe'],
+      });
+      child.on('exit', code => resolve({ exitCode: code }));
+    });
+
+    assert.equal(exitCode, 0,
+      `cat ${credPath} inside sandbox exited with code ${exitCode} — sandbox is denying read on a path the spawn legitimately needs. ` +
+      `~/.claude must NOT be in denyRead per the 2026-05-28 fold-in.`);
+  });
 });