Genswarms Browser Use

Genswarms.Browser — using the browser object

Wiring

# Allowlist mode (fail-closed, default)
%{name: :browser, handler: Genswarms.Browser, config: %{
  mode: :allowlist,
  allowlist_path: "config/browser_allowlist.txt",  # one host per line — fail-closed
  head_chars: 2000,          # compact reply size
  session_ttl_ms: 120_000
  # renderer/resolver/fetcher injectable for tests; default renderer drives
  # the `agent-browser` CLI (must be on PATH); curl via GENSWARMS_CURL_BIN/PATH
}}

# Denylist mode (allow-any except blocklist; requires IP-filtering proxy)
%{name: :browser, handler: Genswarms.Browser, config: %{
  mode: :denylist,
  blocklist_path: "config/browser_blocklist.txt",  # one host per line to deny
  proxy_url: "http://proxy.internal:8080",  # required: deployment-provided IP-filtering egress proxy
  head_chars: 2000,
  session_ttl_ms: 120_000
}}

Runtime grants (allow_sync — 0.2.0)

Trusted objects may extend the allow set live, without a restart:

config: %{
  # …allowlist/denylist config as above, plus:
  grant_sources: [:rally],        # ONLY these senders may allow_sync; absent/[] = disabled
  grants_store: MyApp.Store       # optional: load_grants/0 + save_grant/2 (persistence)
}

• A grant source sends {"action":"allow_sync","hosts":["docs.example.com"], "meta":{…}} → reply {"ok":true,"added":N,"skipped":K,"total":M}. meta is opaque provenance, passed to the store untouched.
• Every host re-passes the package's sanity floor on receipt AND on boot load (bare dotted DNS names only — IP literals, localhost, .local/.internal are skipped and counted). Curate harder upstream: the floor is a backstop, not a policy. The render-time SSRF gate still applies to granted hosts.
• Boot allowset = allowlist file ∪ stored grants; a raising store falls back to the file-only floor. A store WRITE failure keeps the grant in memory (lost on restart, logged loudly). The store is called directly — a store wired against a stale contract (wrong arity) fails loudly, never silently.
• Kill switch: an EMPTY/unreadable allowlist file means nothing is reachable — stored AND runtime grants are suppressed (persisted, noted in the reply, but inactive) until the floor is restored and the object restarts. Emptying the file during an incident actually stops browsing.
• Denylist mode: grants are accepted + persisted (ready for a mode flip) but don't change reachability — the reply carries a note.
• Any other sender gets {"error":"unauthorized"}. The action is deliberately absent from interface/0 — agents are never told it exists; don't add agent slots to grant_sources.
• Each applied grant emits a :browser_grant display event.
• Revocation: delete the store row and restart (the object holds the union in memory).

The containment model (don't weaken it)

Allowlist mode (default — fail-closed)

• Only https:// URLs on allowlisted hosts are fetched/rendered.
• Re-gate on settle: a client-side redirect landing OFF the allowlist destroys the session (never reused) — pinned by checks/browser_regate_settle.
• Compact replies by default: head of main body + nav-link index + size. The agent asks {"full":true} only to have the full body written to ITS OWN workspace file (it greps there) — the page never re-enters conversation context. This is the context-bloat fix; don't return full pages inline.

Denylist mode (allow-any except blocklist)

• Allows https:// URLs to any public host except those in blocklist_path.
• Requires IP-filtering egress proxy (proxy_url config): the proxy must intercept and deny requests to internal / reserved IPs (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 127.0.0.0/8, etc.) to prevent sub-resource SSRF (agent-initiated fetch of internal databases, cloud metadata, etc.). The proxy is YOUR responsibility.
• Compact replies work identically: agent gets head + nav index, can request full body to its workspace file.

Gotchas

• render_failed {:open_failed, ""} → the agent-browser CLI is not on PATH (the default renderer shells out to it). Inject a renderer or install it.
• Denylist mode without proxy: traffic to internal IPs is NOT blocked by the browser itself — a missing or misconfigured proxy will expose your internal networks. Test your proxy (e.g. curl -x http://proxy:8080 http://192.168.1.1) before enabling denylist mode in production.
• Display telemetry rides the :genswarms_objects, :display_wire app env (default [:genswarms, :display]) — set it to your host's wire name if your EventFeed listens elsewhere.