feat(agents-runtime): Sandbox primitive + native (Seatbelt/bwrap) and E2B remote providers#4369
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feat(agents-runtime): Sandbox primitive + native (Seatbelt/bwrap) and E2B remote providers#4369msfstef wants to merge 18 commits into
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Introduce the Sandbox interface and an unrestrictedSandbox provider as the
plumbing for host-isolation work. No default behavior change — all built-in
entities (Horton, Worker) explicitly construct unrestrictedSandbox so they
behave identically to before. See plans/sandbox-design.md.
- New: packages/agents-runtime/src/sandbox/{types,unrestricted}.ts and the
public /sandbox subpath aggregator.
- Tool factories (bash, read, write, edit, fetch_url) now take Sandbox
instead of a workingDirectory string. They delegate FS/exec/fetch to it.
- bash no longer forwards process.env to children. Scrubbed env
(PATH/HOME/USER/LANG/TERM) only. Closes env-var exfil via "echo \$KEY".
- bash description string stops claiming a sandbox that wasn't there.
- read/write/edit add realpath-based path resolution via resolveSafePath
to block symlink-escape from the workspace.
- The standalone fetchUrlTool export is removed; callers must construct
via createFetchUrlTool(sandbox).
- Horton/Worker construct unrestrictedSandbox per wake and dispose in a
finally block. Conformance tests updated to the new signatures.
Tests: 48 new tests across sandbox-unrestricted, sandbox-tool-refactor,
and sandbox-tool-symlink-safety. Existing test suites for bash/write/edit
updated for the new tool signatures. Full agents-runtime suite + agents
suite green; typecheck clean across runtime, agents, and conformance-tests.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
… (PR 6b)
Adds nativeSandbox(), a Sandbox provider that wraps Anthropic's
sandbox-runtime library to enforce host isolation through OS-level
primitives (Seatbelt on macOS, bubblewrap on Linux/WSL2).
Architecture:
- New dependency: @anthropic-ai/sandbox-runtime@0.0.52 (Apache-2.0, pinned).
- src/sandbox/native.ts: implements Sandbox over SandboxManager. Translates
our config (workingDirectory, allowedHosts, extraReadPaths) into the
library's config shape so customers never see the library's API.
- Lazy initialization: SandboxManager is only set up on the first exec()
call. readFile / writeFile / mkdir / fetch are enforced at the TS layer
(path canonicalization + deny overlay; hostname allowlist for fetch).
No proxy startup cost for handlers that don't spawn subprocesses.
- Refcount + single-instance enforcement: one workingDirectory can be
actively exec'd through the OS sandbox at a time in one Node process.
Concurrent exec from a conflicting workingDirectory throws
SandboxError({kind: 'unavailable'}).
- Default deny overlay covers ~/.ssh, ~/.aws, ~/.config/{gcloud,op,gh},
~/.kube, ~/.docker, ~/.netrc, ~/.npmrc, ~/.pgpass, ~/.huggingface,
and ~/Library/Application Support. Documented as incomplete in
plans/sandbox-design.md §5.2; the v2 fix is a curated read-allowlist.
- name: 'native:macos-seatbelt' on Darwin, 'native:linux-bwrap-only'
elsewhere — makes the bwrap-only Linux limitation legible in logs.
- Throws SandboxError({kind: 'unavailable'}) on unsupported platforms
(Windows) with an actionable error pointing to unrestrictedSandbox or
remoteSandbox.
Tests (test/sandbox-native.test.ts):
- Identity, FS policy (deny overlay, allowed reads/writes), fetch policy.
- Lifecycle: re-construction after dispose, concurrent-exec rejection.
- Real OS sandbox integration tests (skipped on unsupported platforms):
basic echo, /etc/sudoers blocked, writes inside cwd allowed.
No default change for Horton/Worker — they still use unrestrictedSandbox.
PR 6d will flip the default and add the Horton home-as-cwd fix.
Also: write-tool test updated to compare canonical (realpath-resolved)
paths in readSet, matching PR 6a's symlink-safety semantics.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Adds remoteSandbox(), a Sandbox provider that delegates host isolation to a
remote workspace (microVM/container) at a SaaS provider. v1 ships an E2B
adapter; additional providers (Vercel, Daytona) are mechanical to add via
the RemoteSandboxClient interface.
Architecture:
- src/sandbox/remote/types.ts: RemoteSandboxClient interface — the narrow
contract each provider adapter implements (exec, readFile, writeFile,
mkdir, kill).
- src/sandbox/remote/e2b.ts: createE2BClient and adaptE2B. Dynamically
imports the 'e2b' package so it remains an *optional peer dependency*.
Customers using the remote provider install e2b separately; no install
cost for everyone else.
- src/sandbox/remote.ts: provider-neutral remoteSandbox factory and the
RemoteSandbox class implementing the Sandbox interface. FS paths are
VM-rooted (default cwd '/work'). Writes outside the working directory
are rejected at the TS layer. dispose() calls client.kill() once;
subsequent operations throw SandboxError({kind:'runtime'}).
The 'client' opt accepts a pre-constructed RemoteSandboxClient, used by
tests (a fake client tracks all calls and serves an in-memory FS) and by
customers who want to wrap the provider SDK with retry/observability
before handing it to us.
sandbox.fetch() runs in the host Node process with a TS-level hostname
allowlist — *not* inside the VM. Documented caveat: to route outbound
traffic through the VM, use sandbox.exec('curl ...'). v1.1 may add a
VM-routed fetch.
Tests (test/sandbox-remote.test.ts, 9 cases):
- Identity (name reflects provider).
- exec delegation with default + override cwd.
- writeFile/readFile roundtrip; writeFile outside cwd rejected.
- mkdir delegation, including recursive walk.
- fetch hostname allowlist rejection.
- dispose calls kill exactly once even on repeat.
- Unknown provider name throws SandboxError({kind:'unavailable'}).
No real e2b account/SDK is needed for the test suite — all tests use the
in-memory fake client.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…(PR 6d) Wires the native sandbox in as the default for built-in entities (Horton, Worker) on macOS and Linux. Behavior change: LLM-driven bash/read/write/ edit/fetch_url tools now run inside Seatbelt (macOS) or bubblewrap (Linux) by default, with the env-scrubbing + symlink-safety from PR 6a and the default deny overlay from PR 6b. - New: src/sandbox/default.ts — chooseDefaultSandbox(workingDirectory, env?) helper. Picks nativeSandbox when SandboxManager.isSupportedPlatform() returns true; otherwise unrestrictedSandbox. - Panic-revert env switch: ELECTRIC_AGENTS_UNRESTRICTED=1 (also accepts 'true'/'yes'/'on', case-insensitive) forces unrestrictedSandbox on any platform. Documented as the emergency lever when the native engine misbehaves; not promoted in customer-facing docs. - Horton and Worker handlers replace their direct unrestrictedSandbox construction with a chooseDefaultSandbox call. No other change to the handler logic; the try/finally dispose pattern from PR 6a stays. Tests (test/sandbox-default.test.ts, 5 cases): - Native chosen on supported platforms. - ELECTRIC_AGENTS_UNRESTRICTED=1 forces unrestricted. - Case-insensitive truthy values (true, yes, on) all force unrestricted. - Unrestricted picked when isNativeSupported() returns false (Windows shape via the testing override). - ELECTRIC_AGENTS_UNRESTRICTED=0 does NOT trigger the panic switch. The agents-desktop home-as-cwd fix (main.ts:1939 'app.getPath(home)' fallback) is deferred to a separate, smaller desktop PR — it's a UX change with its own implications. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…egatives Closes two test-coverage gaps that surfaced during PR 6a-6d review. sandbox-conformance.test.ts (20 cases): - Parameterizes a single set of scenarios over unrestricted, native (real OS sandbox, gated by SandboxManager.isSupportedPlatform), and remote (driven by an in-memory fake matching RemoteSandboxClient). - Asserts the cross-provider contract: writeFile+readFile roundtrip, exec returns an exitCode, dispose is safe, name/workingDirectory exposed, readFile ENOENT propagates. - Encodes the *deliberate* semantic difference: writeFile outside cwd rejects for native/remote (policy-bearing providers) but succeeds for unrestricted (which delegates to node:fs — path security lives in the tool layer's resolveSafePath helper). - Symlink-escape sub-suite for non-remote providers documents that unrestricted does not block symlinks at the sandbox layer (tool layer handles it) while native does. sandbox-native-os.test.ts (5 cases, real OS sandbox only): - bash does not inherit arbitrary parent env vars (closes the __SANDBOX_OS_TEST_SECRET__ exfil path via the OS sandbox). - bash cannot write outside the working directory at the OS level. - bash cannot follow a symlink whose target is in the default deny overlay. Comments explicitly note the v1 denylist's limitation: symlinks to arbitrary /tmp paths *are* readable (option 1 in plans/sandbox-design.md §5.2); only paths inside the deny set are blocked. v2 read-allowlist would change this. - bash with no allowedHosts cannot reach the network (verifies https://1.1.1.1 is refused). - readFile through the TS adapter denies known credential paths under home (~/.ssh, ~/.aws, ~/.config/gcloud). Coverage gap honest-status after this commit: - remoteSandbox against the real E2B SDK is still untested (needs an account). adaptE2B's type translations could drift without us noticing. - Linux bwrap path is not exercised in CI by this machine (macOS dev env). - Horton/Worker full integration through a fake LLM is blocked by the pre-existing better-sqlite3 missing-module error in packages/agents. Test totals: 78 sandbox tests, all green. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The e2b peer dep added in PR 6c was missing from the lockfile (an earlier checkout reverted the install change). This commit lands the lock entries for e2b@2.21.0 and its transitive deps so a fresh pnpm install resolves consistently. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Three integration adjustments after rebasing on origin/main: - Delete packages/agents-runtime/test/tool-path-symlink.test.ts. This was a characterization test from #4354 that documents pre-fix symlink-escape behavior with an explicit "update when realpath resolution lands" note. PR 6a's resolveSafePath helper is that fix; the file's expectations are now contradicted by sandbox-tool-symlink-safety.test.ts. - Trim packages/agents-runtime/test/bash-tool.test.ts: the two characterization tests from #4354 that documented the bash env-leak bug are removed. PR 6a fixed that bug; sandbox-tool-refactor.test.ts has the corresponding assertion ('does not forward arbitrary process.env to children'). The first test in the file (cwd + HOME exposure) stays. - Migrate packages/agents-runtime/test/fetch-url-ssrf.test.ts to the new createFetchUrlTool(sandbox, opts) signature. The assertions still hold for unrestrictedSandbox (NetPolicy SSRF protection is deferred); the test is now explicit about that scope. - Remove the @ts-expect-error directive on the dynamic e2b import in src/sandbox/remote/e2b.ts. With e2b now in the lockfile, TS resolves the package and the directive is unused. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Codecov Report❌ Patch coverage is Additional details and impacted files@@ Coverage Diff @@
## main #4369 +/- ##
==========================================
+ Coverage 55.84% 60.63% +4.78%
==========================================
Files 245 302 +57
Lines 24847 30248 +5401
Branches 6878 8137 +1259
==========================================
+ Hits 13876 18340 +4464
- Misses 10957 11891 +934
- Partials 14 17 +3
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…proxy
Previously sandbox.fetch() on nativeSandbox enforced its hostname policy
via a manual `Set<string>.has(url.hostname)` exact-match check that
duplicated (badly) what `@anthropic-ai/sandbox-runtime`'s HTTP proxy
already does for subprocess egress.
The two pathways now share one policy enforcer (the library's proxy)
with consistent semantics:
- Wildcard patterns (e.g. `*.example.com`)
- IP canonicalization (e.g. `2852039166` → `169.254.169.254`)
- Denied-domains taking precedence over allowed
- Control-character host rejection
- IPv6 zone-ID payload rejection
Implementation:
- Add `undici` as a direct dependency for `ProxyAgent`.
- On `ensureInitialized`, read `SandboxManager.getProxyPort()` and build
a `ProxyAgent('http://127.0.0.1:PORT')` dispatcher.
- `sandbox.fetch()` passes `{ dispatcher }` to global fetch so undici
routes the request through the same proxy that gates `bash`-emitted
egress.
- A 403 with `x-srt-denied` header or undici proxy-refusal error is
translated to `SandboxError({kind: 'policy'})` so callers still see a
consistent policy-rejection shape.
- `dispatcher.close()` runs in `dispose()` to release sockets.
Linux Unix-socket gap documented: `getLinuxHttpSocketPath()` returns
a Unix socket on Linux which `ProxyAgent` does not consume directly.
For now sandbox.fetch on Linux falls back to direct (non-proxy)
network access. exec-driven egress on Linux still routes through the
proxy correctly via the bind-mounted unix socket. A custom undici
dispatcher targeting the unix socket would close this; tracked for a
follow-up.
Tests (test/sandbox-native-proxy-fetch.test.ts, 3 cases):
- Allowed host through the proxy reaches a local HTTP server.
- Disallowed host is refused with SandboxError({kind:'policy'}).
- Wildcard patterns in allowedHosts (e.g. '*.example.com') are accepted
by the library's validator and config — confirming we no longer
shadow the matcher with our own naïve exact-match check.
Existing tests in sandbox-native.test.ts now exercise the proxy
rejection path end-to-end (a real undici/proxy round-trip), not a
synthetic Set.has() check.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…e kill
Two CI-surfaced bugs:
1. **nativeSandbox crashed on Linux runners without `bubblewrap` installed.**
`SandboxManager.isSupportedPlatform()` returns true on any Linux but
the actual `initialize()` call throws when bwrap isn't on PATH. Tests
gated on `isSupportedPlatform()` ran on the Linux runner and exploded
instead of skipping.
Fix: in the nativeSandbox factory and in chooseDefaultSandbox, call
`SandboxManager.checkDependencies()` and surface a missing dependency
as `SandboxError({kind: 'unavailable'})` *before* `initialize()`.
The test gates (sandbox-native, sandbox-native-os,
sandbox-native-proxy-fetch, sandbox-conformance, sandbox-default)
also use `checkDependencies()` so they skip cleanly on hosts where
the runtime tools aren't installed.
chooseDefaultSandbox now falls back to unrestrictedSandbox on a
Linux host without bwrap rather than throwing — keeps the "default
to native, panic to unrestricted" contract from PR 6d intact even
when the native engine is unusable.
2. **timeoutMs test hung on Linux until vitest's 5s default fired.**
`spawn('sh', ['-c', 'sleep 5'])` then `child.kill('SIGTERM')` kills
`sh` immediately but leaves `sleep` orphaned, still holding the
stdio pipes — the `close` event waits for the grandchild to finish
naturally. macOS happened to terminate the tree differently so the
bug only surfaced on the Ubuntu runner.
Fix: spawn with `detached: true` to create a new process group, then
send the signal to `-pid` so the whole tree dies. SIGTERM first,
escalating to SIGKILL after 500ms if anything is still hanging on.
Applied symmetrically in unrestricted.ts and native.ts.
Also: adds the missing changeset entry (`Check Changeset` CI failure).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The factory's eager `checkDependencies()` (added in the previous commit to surface 'unavailable' clearly to users) means that ALL tests in sandbox-native.test.ts crash on a host without bubblewrap, not just the ones that actually exec under the OS sandbox. The CI Linux runner exposed this — the inner `identity`, `filesystem policy`, `fetch policy`, and `lifecycle` describes were previously running on the lazy assumption and need the outer gate now. Coverage of the same TS-policy assertions remains on unsupported hosts via sandbox-conformance.test.ts's unrestricted + fake-remote providers, which are gated per-provider. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…+ AbortSignal
Additive interface changes — no rename of exec, no namespacing. Brings the
adapter contract in line with the May 2026 industry LCD (Vercel/Cloudflare/
E2B/Daytona/ComputeSDK) so future adapters and tools can rely on a broader
filesystem surface.
- types.ts: add readdir/exists/remove/stat to Sandbox, DirEntry/FileStat,
signal?:AbortSignal on SandboxExecOpts.
- unrestricted/native: implement new methods. AbortSignal escalates SIGTERM
then SIGKILL through the existing kill-tree path. FS errors normalized to
SandboxError('runtime') at the adapter boundary so conformance assertions
are stable across providers.
- remote + RemoteSandboxClient: extend contract; E2B adapter prefers
files.list/exists/remove/getInfo when available and falls back to shell
commands (BusyBox/GNU stat compatible) for older SDK shapes.
- write tool: switch read-before-write existence probe to sandbox.exists()
rather than ENOENT detection on readFile.
- conformance: scenarios for exists/stat/readdir/remove/remove-recursive and
an exec(AbortSignal) abort case (skipped semantically for the in-memory
remote fake).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Review pass on the previous commit flagged that throwing on policy-denied paths in exists() drifts from the 2026 LCD semantics shared by Vercel, Cloudflare, and E2B — they all treat exists() as a safe-probe that returns false in both the missing and denied cases. Flipping native to match; unrestricted has no policy boundary so its behavior is unchanged. Also adds SandboxExecResult.aborted so callers can disambiguate caller-side AbortSignal cancellation from naturally-delivered signals and from timeoutMs expiry — the OS signal field is unreliable for that purpose under musl / on Alpine builds. E2B shell fallbacks hardened: readdir now uses `find -print0` to be newline-safe and preserves the file/dir/symlink distinction via `%y`; stat() validates a 3-field output structure before parsing instead of unioning two mutually-incompatible formats; failure paths synthesize classified errno codes (ENOENT/EACCES/EIO) so SandboxError messages are never blank. Conformance gains four cases: stat on missing path, remove on missing path, remove on non-empty dir without recursive, and a pre-aborted exec that returns immediately. The mid-flight abort test now asserts the new aborted boolean. Remote (fake) is skipIf'd on abort cases since the fake client has no abort plumbing. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…licy)
Two interface additions that line the Sandbox contract up with the 2026
LCD (Vercel/Cloudflare/E2B publish both as first-class methods).
- types.ts: NetworkPolicy discriminated union (allow-all/deny-all/allowlist),
getUrl({port, protocol}) and updateNetworkPolicy(policy) on Sandbox.
- unrestricted: getUrl returns loopback URL; updateNetworkPolicy records
policy without enforcement (documented no-op — unrestricted has no
boundary).
- native: getUrl returns loopback (Seatbelt + bwrap both leave 127.0.0.1
reachable from inside). updateNetworkPolicy wires SandboxManager
.updateConfig() — the library API confirmed at sandbox-manager.d.ts:36
exposes mid-session reconfiguration of the MITM proxy's allowedDomains.
NativeSandboxOpts.allowedHosts is preserved but deprecated in favor of
initialNetworkPolicy; the latter wins when both supplied.
- remote: TS-side allowedHosts Set replaced with a NetworkPolicy state
machine; updateNetworkPolicy reconfigures the host-process gate and
logs once that VM-side egress is not reconfigured (E2B doesn't expose
the necessary API). getUrl delegates to a new optional client.getUrl()
hook so the contract remains pluggable.
- RemoteSandboxClient: add optional getUrl({port, protocol}); falls back
to SandboxError('unavailable') when absent.
- conformance: add ProviderCapabilities descriptor (supportsAbort/
supportsRealGetUrl/enforcesNetworkPolicy) so per-provider quirks become
declarative instead of name-string branching. Two new scenarios:
getUrl returns a port-bearing URL (or rejects unavailable), and
updateNetworkPolicy(deny-all) flips subsequent fetch to policy-rejected.
Abort-skip predicates migrated to capability checks.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
A fourth sandbox provider that runs each Sandbox instance inside a
dedicated Docker container. Targets local development and self-hosted
deployments where neither macOS Seatbelt nor a paid microVM provider is
appropriate. Built on dockerode (added as an optional peer dependency).
Hardening
---------
The HostConfig is hardcoded and not overrideable from DockerSandboxOpts:
- CapDrop: ['ALL'], CapAdd: [] — no caps means mount/chroot/su fail
- SecurityOpt: ['no-new-privileges:true']
- Privileged: false
- PidsLimit / Memory / NanoCpus — sensible defaults, opt-out via opts.resources
- Ulimits: nofile=2048, nproc=1024
- IpcMode: 'none'
- AutoRemove: true (ephemeral)
- NetworkMode: 'none' by default; switches to 'bridge' only when an
allowlist or exposedPorts is set
- Default image pinned by digest (node:20-alpine multi-arch manifest)
- extraMounts entries enforce readOnly: true at the type level and
reject any hostPath matching /docker\.sock$/ at runtime so the docker
socket cannot be exposed back to sandboxed code.
ReadonlyRootfs is intentionally *not* enabled by default — dockerode's
putArchive operates at the storage-driver layer and gets rejected on a
read-only rootfs even when the target is a tmpfs/volume. Operators who
want it must drive all writes via sandbox.exec.
Filesystem
----------
src/sandbox/docker/fs.ts provides putFile/getFile via dockerode's
putArchive/getArchive (small in-memory tar writer, no extra dep) and
exec-based readdir/exists/remove/stat. readdir does three POSIX
`find -type X -print0` passes so it works on both GNU find and BusyBox
(alpine) — newline-safe via NUL delimiting.
Network
-------
src/sandbox/docker/proxy.ts ships a minimal HTTP/HTTPS forward proxy
(~150 LoC, node:http + CONNECT) with a dynamic allowlist that
updateNetworkPolicy mutates in place. Container env is set with
HTTP_PROXY=http://host.docker.internal:<port> so tools that respect
proxy env vars (curl, python requests, undici with ProxyAgent, browser
clients) route through it. Programs that bypass HTTP_PROXY (raw TCP,
Node's built-in fetch without explicit setGlobalDispatcher) leak
through Docker's NAT — documented gap; v2 needs a sidecar netns / nft
filter for full sealing.
Lifecycle
---------
One long-lived container per Sandbox instance (PID 1 = sleep keepalive).
Each exec uses container.exec() with stream demux. timeoutMs and
AbortSignal both wire to a kill-everything-but-PID-1 helper that
enumerates /proc and SIGKILLs to side-step a dockerode stream-close
race. dispose() removes the container even if AutoRemove already fired.
Testing
-------
- test/helpers/docker-probe.ts: top-level await isDockerAvailable() so
describe.skipIf works at import time. Tests skip cleanly with a
warning when the daemon is unreachable.
- test/sandbox-docker.test.ts: 13 integration tests against real
Docker — roundtrip, hardening (caps, docker.sock, mount, chroot),
timeouts, AbortSignal, port forwarding, policy enforcement at the
proxy boundary, leftover-container sweep. Runs in <10s on a warm
machine.
- test/sandbox-docker-smoke.test.ts: ad-hoc smoke probes that exercise
CapEff/CapPrm/CapBnd ≡ 0, container /etc/passwd isolation, /Users
invisibility, raw-CONNECT proxy allow vs deny.
All 132 sandbox tests pass on macOS + OrbStack.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…cker
Add `KNOWN_ADAPTERS` const to the public sandbox barrel and assert in the
conformance suite that every slug is exercised by exactly one provider —
adding a new adapter without registering it in the conformance suite
will now fail CI.
Wire the docker adapter into the cross-provider conformance loop with
a `dockerAvailable`-gated `enabled` flag. The describe gating relies on
the existing top-level await probe at `test/helpers/docker-probe.ts`
(skips clean on machines without Docker, no CI workflow change needed —
Ubuntu runners have Docker pre-installed, macOS doesn't and skips
gracefully).
Replace remaining provider-name string equality checks (`provider.name
=== 'remote (fake)'`, `=== 'unrestricted'`) with two declarative axes
on `ProviderFactory`:
- `adapter: KnownAdapter` — KNOWN_ADAPTERS slug, used by the symlink
test branch and the unrestricted-no-policy branch
- `outsideKind: 'host-tempdir' | 'etc-passwd'` — controls which path
the "writeFile outside the working directory" probe uses, replacing
the brittle name match
73 conformance scenarios now run against the docker provider (in ~12s
on a warm machine, OrbStack on M-series). All 151 sandbox tests pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…low-all
Address the high-severity findings from the final security review.
Docker read-side policy (R1)
----------------------------
readdir, stat, and readFile now call assertReadable() to enforce the
workingDirectory boundary, matching native's behavior. Previously
docker.readdir('/etc') would silently succeed and enumerate the
container's filesystem — only writeFile / mkdir / remove were gated.
exists() also goes through the new isReadable() helper but returns
false on denial (safe-probe semantics, consistent with the rest of
the adapter set).
Proxy SSRF guards (R2)
----------------------
The docker allowlist proxy now refuses CONNECT and plain-HTTP requests
to literal RFC1918 (10/8, 172.16/12, 192.168/16, 100.64/10 CGNAT),
loopback (127/8), unspecified (0/8), link-local + cloud metadata
(169.254/16, 169.254.169.254 AWS/GCP), IPv6 loopback (::1), and IPv6
link-local / unique-local (fe80::, fc::, fd::). The guard runs after
the hostname allowlist and rejects regardless of the policy decision —
even if a user explicitly allows 169.254.169.254 they cannot reach it.
Plain-HTTP proxying now overrides the caller-supplied Host header with
the target's authority, so an attacker can no longer split an
allowlisted absolute URL from a different vhost via the Host header.
proxy-authorization and proxy-connection hop-by-hop headers are also
stripped before forwarding.
Port bindings bind to 127.0.0.1 only (was 0.0.0.0) so dev-machine
sandboxes don't expose services across the LAN.
Native allow-all (correctness)
------------------------------
The upstream @anthropic-ai/sandbox-runtime config validator rejects
bare '*' in network.allowedDomains as "too broad". Our previous
policyToAllowedDomains returned ['*'] for mode:'allow-all', which would
have silently broken init. Throw SandboxError('unavailable') with a
pointer to unrestrictedSandbox instead.
New conformance — sandbox-docker.test.ts:
- "read-side methods enforce the working directory boundary": asserts
readFile / readdir / stat throw policy and exists() returns false
for /etc paths.
New smoke — sandbox-docker-smoke.test.ts: even when explicitly allowed,
CONNECT to 169.254.169.254, 127.0.0.1, and 10.0.0.1 all return 403.
149 + 2 new tests pass; conformance still green across all 4 adapters.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The underlying SandboxManager from @anthropic-ai/sandbox-runtime is a
process-global singleton: two nativeSandbox instances with different
working directories conflict and throw SandboxError('unavailable'). The
agents-runtime hosts many agent entities concurrently, each with its own
working directory, so this constraint is incompatible with the product.
dockerSandbox now covers the strong-isolation use case (no singleton,
multi-instance safe). unrestrictedSandbox + tool-layer policy (env
scrubbing, symlink resolution, fetch SSRF guards) covers the dev case.
- Delete src/sandbox/native.ts and the three native test files.
- Drop 'native' from KNOWN_ADAPTERS; drop nativeSandbox /
NativeSandboxOpts / ChooseDefaultSandboxOpts exports.
- Simplify chooseDefaultSandbox to always return unrestrictedSandbox.
Remove the ELECTRIC_AGENTS_UNRESTRICTED env var — it only existed to
revert from native to unrestricted, which is now the default.
- Drop the native provider entry from the conformance suite; the
KNOWN_ADAPTERS round-trip assertion now covers unrestricted/remote/docker.
- Drop @anthropic-ai/sandbox-runtime from dependencies; regenerate
pnpm-lock.yaml.
- Update sandbox-design.md and the changeset to reflect the new lineup.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Adds the
Sandboxprimitive to the agents runtime and ships three providers:unrestrictedSandbox— explicit pass-through overnode:fs/child_process. The name is the warning.nativeSandbox— wraps@anthropic-ai/sandbox-runtime(Apache-2.0) for Seatbelt on macOS and bubblewrap on Linux/WSL2. Default deny overlay for~/.ssh,~/.aws,~/.config/{gcloud,op,gh},~/.kube,~/.docker,~/.netrc,~/.npmrc,~/.pgpass,~/.huggingface,~/Library/Application Support. Lazy-initialized: pure FS/fetch policy without spinning up proxy servers.remoteSandbox({provider: 'e2b'})— adapter for E2B's npm SDK, loaded as an optional peer dependency. TheRemoteSandboxClientinterface makes it mechanical to add Vercel/Daytona/etc.Built-in entities (Horton, Worker) now default to native sandboxing on macOS/Linux via a new
chooseDefaultSandbox(workingDirectory, env?)helper.ELECTRIC_AGENTS_UNRESTRICTED=1is the documented panic-revert env switch.Folded into PR 6a are three behavior-relevant security fixes:
process.envto children (closes$ANTHROPIC_API_KEYexfil)Design doc:
plans/sandbox-design.md. Investigation that motivated this:plans/sandboxing-investigation.md.Commits in this branch
2acaa5695— PR 6a:Sandboxinterface +unrestrictedSandbox+ tool refactor + env scrub + symlink fixes1bd193cab— PR 6b:nativeSandboxvia@anthropic-ai/sandbox-runtime7da404428— PR 6c:remoteSandbox+ E2B adaptered0a231e8— PR 6d:chooseDefaultSandbox+ Horton/Worker default to nativec6a9ffc54— Cross-provider conformance suite + real-OS negative tests fornativeSandboxWhat this primitive is and is not
Targets host isolation for LLM-driven tool calls (escape of cwd, env-var exfil, arbitrary network egress, symlink traversal). Explicitly does not address prompt-injection-driven misuse of legitimate tools — that's a separate
ToolGateprimitive on its own schedule (seeplans/sandboxing-investigation.md).Documented gaps (in §10 of the design doc):
'native:linux-bwrap-only'makes this legible in logs. FuturenativeSandboxStrongtier with Codex-derived helper is the escalation.sandbox-execis officially deprecated; lazy-init + startup smoke test catches profile drift.sandbox.fetch()onremoteSandboxruns in the host Node process, not inside the VM. To route through the VM, usesandbox.exec('curl ...').Test plan
Local (this branch, macOS): 78 sandbox tests green, including 5 real-OS Seatbelt negative tests (
sandbox-native-os.test.ts) verifying env scrubbing, network deny, write blocking, deny-overlay symlink blocking. 20 cross-provider conformance tests pin the contract across providers. typecheck clean onagents-runtime,agents,agents-server-conformance-tests.remoteSandbox({provider: 'e2b'})against a real E2B account (theadaptE2Btranslation isn't unit-tested against the real SDK)better-sqlite3builds viapnpm approve-buildssopackages/agentstest suite runs (pre-existing pnpm 10 issue, blocks horton/worker integration tests)ELECTRIC_AGENTS_UNRESTRICTED=1in dev loop falls back to unrestricted as expecteddrizzle-orm/postgres-jsimport inruntime-dsl.test.tsif you want that suite green too (not from this branch)Known unrelated test failures on
mainpackages/agents-runtime/test/runtime-dsl.test.ts— fails to importdrizzle-orm/postgres-jsfrom agents-server. Pre-existing.packages/agents/test/*— fails onbetter-sqlite3missing native module. Pre-existing pnpm 10 build-script gating; not introduced by this branch.Both confirmed pre-existing via
git stash && pnpm test && git stash pop.🤖 Generated with Claude Code