feat(antigravity): add experimental native Messages provider

Cargo.toml

@@ -46,6 +46,10 @@ ratatui = "0.29"
 crossterm = "0.28"
 jiff = { version = "0.2", default-features = false, features = ["std", "tz-system", "tzdb-zoneinfo"] }
 tiktoken-rs = { version = "0.12", default-features = false }
+jsonschema = { version = "=0.59.0", default-features = false, features = ["idna"] }
+
+[target.'cfg(unix)'.dependencies]
+libc = "=0.2.186"
 
 [dev-dependencies]
 tokio = { version = "1", features = ["test-util"] }

README.md

@@ -105,6 +105,33 @@ The opt-in Images API returns base64 image data and consumes the signed-in accou
 Run `claude-code-proxy models` for the current catalog or
 `claude-code-proxy models --full` for every dynamic Cursor alias.
 
+An additional **experimental, default-off native Antigravity Argon adapter** supports
+only `antigravity/gemini-4-argon-low`, `antigravity/gemini-4-argon-medium`, and
+`antigravity/gemini-4-argon-high`. It does not run or import credentials from `agy`.
+Its default HTTP User-Agent is `claude-code-proxy/<package version>`. An explicit
+provider-specific override affects only native generation/project discovery,
+not OAuth; it is compatibility metadata, not verified official-client identity.
+Use a fresh session for every model/tier/profile change. Real Google OAuth,
+entitlement, native tool round trips and all three tiers remain live-validation
+gates; offline tests are not evidence of account access. See the
+[Antigravity limitations](docs/src/content/docs/reference/compatibility-and-limitations.md#experimental-native-antigravity-argon)
+and [configuration](docs/src/content/docs/reference/configuration.md#experimental-antigravity)
+before explicitly enabling it. Existing provider defaults and aliases are unchanged.
+
+Antigravity login defaults to automatic browser/loopback completion. On Unix,
+`claude-code-proxy antigravity auth login --manual` instead prints a browser URL
+and accepts the **code displayed by the completion page** through visible input in
+your local foreground terminal. The code is sensitive: keep your screen,
+scrollback and recordings private. Short codes are fully visible; longer input
+shows its end with a `<` marker and total character count. A known terminal width
+of at least 10 columns is required; changing width cancels. It does not open a
+browser or callback listener.
+The explicitly configured OAuth client must permit
+`https://antigravity.google/oauth-callback`; a loopback-only client may not work.
+Cancel on browser errors or no displayed code; there is no automatic fallback.
+Never paste a code/token into chat, shell arguments or logs. See the configuration
+reference for PKCE/state distinctions, terminal bounds and unverified live gates.
+
 > [!WARNING]
 > The proxy accepts local requests without client authentication. It binds to
 > `127.0.0.1` by default. Protect any non-loopback listener with a firewall or

docs/src/content/docs/reference/command-reference.md

@@ -70,6 +70,7 @@ claude-code-proxy <provider> auth <action>
 | `kimi` | Device code | Unsupported | User, expiry, scope, storage | Delete proxy credential |
 | `grok` | Browser PKCE | Device code | Expiry and storage | Delete proxy credential |
 | `cursor` | Browser polling flow | Unsupported | Source, claims, expiry | Delete proxy credential |
+| `antigravity` (experimental) | Browser PKCE; opt-in Unix `--manual` paste-back | Unsupported | Safe local readiness, optional `--json` | Delete only Antigravity credential |
 
 Examples:
 
@@ -80,7 +81,54 @@ claude-code-proxy kimi auth status
 claude-code-proxy cursor auth logout
 ```
 
-A missing credential makes `auth status` exit with status 1. Other provider command failures exit with status 2. Successful commands exit with status 0.
+For existing providers, a missing credential makes `auth status` exit with status 1. Other provider command failures exit with status 2. Successful commands exit with status 0.
+
+Antigravity auth commands work even while inference is disabled:
+
+```sh
+claude-code-proxy antigravity auth status --json
+claude-code-proxy antigravity auth login
+claude-code-proxy antigravity auth login --manual
+claude-code-proxy antigravity auth logout
+```
+
+Configure your explicit OAuth client ID before login; see
+[Antigravity configuration](/reference/configuration/#experimental-antigravity).
+Without `--manual`, browser opening and the ephemeral loopback callback are
+unchanged. Experimental `--manual` is Unix-only: it requires terminal stdin and a
+foreground controlling terminal, prints the authorization URL there, and opens
+neither a browser nor a callback listener. The configured client must permit the
+exact hosted redirect `https://antigravity.google/oauth-callback`.
+
+Open the URL in your browser, select the intended account, then copy the **code
+displayed by the completion page** into the visible local terminal prompt. The
+code is sensitive: keep screens, scrollback, screenshots and recordings private.
+The input row shows a character count; short codes fit in full, while `<` marks
+that only the end of longer input is visible. All entered characters remain part
+of the completion, up to the unchanged 8192-byte limit. A known terminal width of
+at least 10 columns is required; changing width cancels rather than risking
+incorrect wrapped editing. Output modes that translate carriage returns or letter
+case are refused, not silently changed.
+The page removes `code` from its address bar; copying that address afterward does not
+supply the code. Cancel if the browser reports an error (such as
+`redirect_uri_mismatch`) or displays no code. There is no automatic callback,
+client or endpoint fallback. Never put a code in command arguments, chat or logs.
+
+Input is limited to 8192 printable ASCII bytes and 180 seconds, with at most
+three empty-entry reprompts under the same deadline. Backspace edits; Enter
+submits; Ctrl-C/Ctrl-D cancel. Pipes and non-Unix manual mode are rejected before
+URL emission. Bare codes rely on server-enforced fresh S256 PKCE, **not returned
+state validation**; a complete redirect URL, if separately available with its
+code intact, additionally requires an exact matching state and redirect target.
+See configuration for security and terminal-restoration limitations.
+
+`status --json` is Antigravity-only and emits schema version 1, `provider:
+antigravity`, plus the safe provider descriptor documented under
+[model discovery](/reference/http-api/#get-v1models). A successfully emitted
+report exits 0 even for missing/invalid/unready credentials. Inspection performs
+no network, refresh, directory creation or writes. CLI readiness describes this
+CLI's configuration, not a different running proxy, and never proves live access.
+Auth invocation failures exit nonzero. No existing provider gains a `--json` flag.
 
 Logout removes the local proxy-owned credential. It does not call the provider to revoke a refresh token.