feat(antigravity): Claude CCA wire fidelity

docs-site/src/content/docs/guides/providers.md

@@ -115,7 +115,7 @@ ocx logout <provider>
 | `kimi` | `openai-chat` | `https://api.kimi.com/coding/v1` | Kimi K2.7/K2.6/K2.5 coding models. |
 | `nous` | `openai-chat` | `https://inference-api.nousresearch.com/v1` | Nous Research subscription gateway (same backend Hermes Agent uses). Device-grant login against `portal.nousresearch.com`; the access token is the per-request inference JWT. Mixed paid + `:free` model catalog (`tencent/hy3:free`, `stepfun/step-3.7-flash:free`, ...) discovered live from the signed-in account. Refresh tokens are single-use and rotated on every refresh. |
 | `kiro` | `kiro` | `https://runtime.us-east-1.kiro.dev` | Initial login imports the installed, signed-in `kiro-cli` session (on Unix, install with `curl -fsSL https://cli.kiro.dev/install` &#124; `bash`; on Windows PowerShell, use `irm 'https://cli.kiro.dev/install.ps1'` &#124; `iex`; then run `kiro-cli login`). **Add account** logs `kiro-cli` out, starts a fresh browser login that switches the account used by `kiro-cli`, and stores account-scoped profile metadata. Existing OpenCodex accounts are preserved, and cancellation or failure restores the previous `kiro-cli` session. |
-| `google-antigravity` | `google` | `https://daily-cloudcode-pa.googleapis.com` | Google OAuth over the Cloud Code Assist wire. Live discovery uses CCA's authenticated `v1internal:fetchAvailableModels` endpoint and publishes the agent models available to the signed-in account; the maintained catalog remains the fallback. |
+| `google-antigravity` | `google` | `https://daily-cloudcode-pa.googleapis.com` | Google OAuth over the Cloud Code Assist wire. Live discovery uses CCA's authenticated `v1internal:fetchAvailableModels` endpoint and publishes the agent models available to the signed-in account; the maintained catalog remains the fallback. See [Claude on Antigravity](#claude-on-antigravity-cloud-code-assist) below. |
 | `cursor` | `cursor` | `https://api2.cursor.sh` | Experimental PKCE login, live HTTP/2 transport with an opt-in HTTP/1.1 compatibility path, and account-filtered model discovery. |
 | `github-copilot` | `openai-chat` | `https://api.githubcopilot.com` | Experimental. GitHub device flow + `copilot_internal` exchange (VS Code OAuth client). Requires an active Copilot subscription; not an official third-party API. |
 
@@ -153,6 +153,23 @@ cat accounts.json | ocx account import google-antigravity --format cockpit-tools
 
 Inline JSON and extra positional arguments are rejected. Keep exported files private and delete or store them securely after import.
 
+### Claude on Antigravity (Cloud Code Assist)
+
+The `google-antigravity` provider routes Claude models through Google's Cloud Code Assist (Antigravity)
+wire rather than Anthropic's native API. opencodex translates requests and responses at the Gemini
+format envelope: tool use/result pairing follows Anthropic semantics (including stable `functionCall.id`
+/ `functionResponse.id` fields), and Claude thinking blocks keep their `thoughtSignature` values across
+turns.
+
+CCA Claude models reject histories that end with an assistant (model) turn — upstream treats that as
+prefill. opencodex strips trailing model turns when safe and appends a `(continue)` user nudge when the
+history would otherwise end on model output (for example after context compaction or interrupted-turn
+replay). Histories that already end on a user message or tool result are left unchanged.
+
+Antigravity exposes only SSE transport. Unary (non-streaming) callers still go through the same
+`parseStream` path; plain JSON bodies without `data:` framing are rejected as truncated SSE rather
+than parsed as a separate JSON response format.
+
 ### OAuth reliability
 
 opencodex coordinates token refresh and Codex pool routing so concurrent requests do not race the

src/adapters/google-antigravity-hosts.ts

@@ -0,0 +1,26 @@
+const DAILY_ANTIGRAVITY_HOST = "https://daily-cloudcode-pa.googleapis.com";
+const PROD_ANTIGRAVITY_HOST = "https://cloudcode-pa.googleapis.com";
+
+/**
+ * Return the configured Antigravity endpoint and, for Google's known daily/prod hosts
+ * only, its daily/production peer. Custom baseUrl values stay single-host.
+ */
+export function antigravityHostCandidates(configuredBase: string): string[] {
+  const configured = configuredBase.replace(/\/+$/, "");
+  if (configured === DAILY_ANTIGRAVITY_HOST) {
+    return [DAILY_ANTIGRAVITY_HOST, PROD_ANTIGRAVITY_HOST];
+  }
+  if (configured === PROD_ANTIGRAVITY_HOST) {
+    return [PROD_ANTIGRAVITY_HOST, DAILY_ANTIGRAVITY_HOST];
+  }
+  return [configured];
+}
+
+/** OAuth bearer requests must not use a cleartext host, even if generic baseUrl config allows http. */
+export function isAntigravityHttpsHost(host: string): boolean {
+  try {
+    return new URL(host).protocol === "https:";
+  } catch {
+    return false;
+  }
+}

src/adapters/google-antigravity-tools.ts

@@ -0,0 +1,94 @@
+import type {
+  OcxAssistantMessage,
+  OcxMessage,
+  OcxToolCall,
+  OcxToolResultMessage,
+} from "../types";
+
+function isAssistantToolCall(message: OcxMessage): message is OcxAssistantMessage {
+  return message.role === "assistant";
+}
+
+function isToolResult(message: OcxMessage): message is OcxToolResultMessage {
+  return message.role === "toolResult";
+}
+
+/**
+ * Repair incomplete tool exchanges before assigning provider-visible ids.
+ *
+ * CCA translates Gemini function calls and responses into Anthropic tool blocks,
+ * which requires both sides of every exchange. A result is valid only when its
+ * call appeared earlier in the history, and a call is valid only when a result
+ * appears later. Filtering the history first also prevents orphan results from
+ * reserving ids in the request-scoped allocator.
+ *
+ * The allocator maps one raw id to one wire id, so a second complete exchange
+ * that reuses the same raw id would serialize as a colliding pair. Keep only
+ * the first matched occurrence per raw id.
+ */
+export function repairGoogleToolPairs(messages: readonly OcxMessage[]): OcxMessage[] {
+  const pendingCalls = new Map<string, Array<{ messageIndex: number; partIndex: number }>>();
+  const seenRawCallIds = new Set<string>();
+  const matchedCallParts = new Set<string>();
+  const matchedResultIndexes = new Set<number>();
+
+  const enqueueCall = (id: string, messageIndex: number, partIndex: number) => {
+    if (seenRawCallIds.has(id)) return;
+    seenRawCallIds.add(id);
+    const queue = pendingCalls.get(id) ?? [];
+    queue.push({ messageIndex, partIndex });
+    pendingCalls.set(id, queue);
+  };
+
+  for (let messageIndex = 0; messageIndex < messages.length; messageIndex++) {
+    const message = messages[messageIndex]!;
+    if (isAssistantToolCall(message)) {
+      message.content.forEach((part, partIndex) => {
+        if (part.type !== "toolCall") return;
+        enqueueCall((part as OcxToolCall).id, messageIndex, partIndex);
+      });
+      continue;
+    }
+    if (!isToolResult(message)) continue;
+    const queue = pendingCalls.get(message.toolCallId);
+    const slot = queue?.shift();
+    if (!slot) continue;
+    matchedCallParts.add(`${slot.messageIndex}:${slot.partIndex}`);
+    matchedResultIndexes.add(messageIndex);
+  }
+
+  const repaired: OcxMessage[] = [];
+  for (const [messageIndex, message] of messages.entries()) {
+    if (isToolResult(message)) {
+      if (matchedResultIndexes.has(messageIndex)) repaired.push(message);
+      continue;
+    }
+    if (!isAssistantToolCall(message)) {
+      repaired.push(message);
+      continue;
+    }
+
+    const content = message.content.filter((part, partIndex) =>
+      part.type !== "toolCall" || matchedCallParts.has(`${messageIndex}:${partIndex}`));
+    if (content.length > 0) {
+      repaired.push(content.length === message.content.length ? message : { ...message, content });
+    }
+  }
+  return repaired;
+}
+
+/**
+ * Claude interprets a final model turn as a prefilled assistant response.
+ * CCA expects the next turn to be generated instead, except when that model
+ * turn is the entire conversation and must remain as the initial context.
+ */
+export function stripTrailingClaudePrefill(contents: unknown[]): boolean {
+  let strippedModelTail = false;
+  while (contents.length >= 2) {
+    const last = contents[contents.length - 1];
+    if (typeof last !== "object" || last === null || (last as { role?: unknown }).role !== "model") break;
+    contents.pop();
+    strippedModelTail = true;
+  }
+  return strippedModelTail;
+}

src/adapters/google-errors.ts

@@ -15,6 +15,12 @@ function googleErrorDetail(payloadText: string): { message?: string; status?: st
   };
 }
 
+const ANTIGRAVITY_GEO_BLOCKED_MARKER = "user location is not supported for the api use";
+
+export function isAntigravityGeoBlockedBody(payloadText: string): boolean {
+  return payloadText.toLowerCase().includes(ANTIGRAVITY_GEO_BLOCKED_MARKER);
+}
+
 function classifyGoogle(label: string, status: number | undefined, enumStatus: string | undefined, text: string): string {
   const lower = `${enumStatus ?? ""} ${text}`.toLowerCase();
   const quotaExhausted =
@@ -29,6 +35,7 @@ function classifyGoogle(label: string, status: number | undefined, enumStatus: s
   if (status === 401 || enumStatus === "UNAUTHENTICATED" || lower.includes("unauthenticated") || lower.includes("invalid authentication") || lower.includes("expired")) {
     return `${label} authentication failed`;
   }
+  if (isAntigravityGeoBlockedBody(lower)) return `${label} location not supported`;
   if (status === 403 || enumStatus === "PERMISSION_DENIED" || lower.includes("permission denied") || lower.includes("access denied")) {
     return `${label} access denied`;
   }