Files

Nikketryhard 6a07786c4e feat: implement headless LS authentication via state sync

Reverse-engineered the UnifiedStateSyncUpdate protocol:
- initial_state field is bytes (not string), contains serialized Topic proto
- Map key for OAuth is 'oauthTokenInfoSentinelKey'
- Row.value is base64-encoded OAuthTokenInfo protobuf
- OAuthTokenInfo includes access_token, token_type, expiry (Timestamp)
- Set far-future expiry (2099) to prevent token expiry errors

Also fixed:
- PushUnifiedStateSyncUpdate returns proper empty proto response
- Stream keep-alive avoids sending empty envelopes (LS rejects nil updates)
- uss-enterprisePreferences topic handled (empty initial state)

2026-02-15 21:40:35 -06:00

4.3 KiB

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Standalone LS for Proxy Isolation

Status: ✅ FULLY IMPLEMENTED (incl. headless mode + MITM)

Two modes available:

Normal standalone (default) — steals config from running Antigravity, optional UID isolation
Headless (--headless) — fully independent, no running Antigravity required

Headless Mode

Pass --headless to the proxy. This:

Generates its own CSRF token (random UUID)
Passes -extension_server_port=0 to the LS (disables extension server callbacks)
Passes -standalone=true to the LS binary (built-in standalone flag)
Uses HTTPS_PROXY env var for MITM (no iptables/sudo required)
No /proc scanning, no dependency on running Antigravity

# Headless (no Antigravity needed)
RUST_LOG=info ./target/release/antigravity-proxy --headless

# With MITM disabled
./target/release/antigravity-proxy --headless --no-mitm

Normal Standalone Mode

The default mode (disable with --no-standalone):

Discovers extension_server_port and csrf_token from the real LS (via /proc/PID/cmdline)
Picks a random free port
Builds init metadata protobuf (via proto::build_init_metadata())
Spawns the LS binary with correct args and env vars
Feeds init metadata via stdin, then closes it
Waits for TCP readiness (retry loop)
Kills the child on proxy shutdown (via Drop)

UID Isolation (MITM mode)

When scripts/mitm-redirect.sh install has been run:

The antigravity-ls system user exists
iptables redirects that UID's port-443 traffic → MITM proxy port
The proxy spawns the LS via sudo -n -u antigravity-ls
Environment variables (SSL_CERT_FILE, etc.) are passed via /usr/bin/env
A combined CA bundle (system CAs + MITM CA) is written to /tmp/antigravity-mitm-combined-ca.pem
Only the standalone LS traffic is intercepted — no impact on other software

LS Binary Flags (Reference)

From language_server_linux_x64 --help:

Flag	Default	Description
`-standalone`	`false`	Whether to run in standalone mode
`-extension_server_port`	`0`	Extension server port. If 0, not used
`-csrf_token`	`""`	CSRF token for RPC auth
`-server_port`	`42100`	Port for LS ↔ extension
`-enable_lsp`	`false`	Enable LSP protocol
`-cloud_code_endpoint`	`""`	CCPA API URL
`-parent_pipe_path`	`""`	Monitors parent process liveness

Key Technical Details

Init metadata protobuf field 34 = detect_and_use_proxy (1=ENABLED)
Model IDs: M18=Flash, M8=Pro-High, M7=Pro-Low, M26=Opus4.6, M12=Opus4.5
LS binary: /usr/share/antigravity/resources/app/extensions/antigravity/bin/language_server_linux_x64
API endpoint: daily-cloudcode-pa.googleapis.com/v1internal:streamGenerateContent?alt=sse

Test Results (2026-02-15)

Endpoint	Result
`GET /health`	OK
`GET /v1/models`	OK, 5 models
`GET /v1/sessions`	OK
`GET /v1/quota`	OK, real plan/credits
`GET /v1/usage`	OK, real MITM tokens
`POST /v1/responses` (sync)	OK
`POST /v1/responses` (stream)	OK, full SSE event set
`POST /v1/responses` (multi-turn)	OK, context preserved
`POST /v1/responses` (tools)	OK, function calls captured
`POST /v1/responses` (images)	OK, MITM injection
`POST /v1/chat/completions`	OK
`POST /v1/gemini`	OK
`GET/POST /v1/search`	OK, grounding + citations
MITM interception	OK, TLS decrypt + parse
MITM request modification	OK, tools/images/params
MITM usage capture	OK, per-model token counts
MITM error capture	OK, instant client feedback
UID isolation	OK, no side effects

4.3 KiB Raw Blame History