feat(wire): native Google/Gemini wire codec (#317)

src/compress-tools.ts

@@ -610,3 +610,82 @@ export const ABSORB_TOOL_OPENAI = {
     parameters: ABSORB_PARAMETERS,
   },
 };
+
+// Gemini native format: flat `{ name, description, parameters }` function
+// declarations (no `{type:"function"}` wrapper), injected as
+// `tools[].functionDeclarations`.
+export const COMPRESS_TOOL_GOOGLE = {
+  name: COMPRESS_TOOL_NAME,
+  description: COMPRESS_TOOL.description,
+  // `anyOf` is rejected by older API revisions, so `content` declares the
+  // object form; a JSON-encoded string of that array is still accepted by
+  // parseCompressInput, and the line form (a summary whose first line is
+  // 'm00150–m00220 optional topic') is documented in the description.
+  parameters: {
+    type: "object",
+    properties: {
+      topic: {
+        type: "string",
+        description: "Optional short title for the compressed range",
+      },
+      content: {
+        type: "array",
+        description:
+          "One or more ranges to compress into separate summary blocks. Object form: {startId,endId,summary,topic?}. A JSON-encoded string of that array is also accepted; in the line form the summary begins with its own first line 'm00150–m00220 optional topic', the rest being the summary markdown verbatim. REQUIRED — compress without content is invalid.",
+        items: {
+          type: "object",
+          properties: {
+            topic: { type: "string" },
+            startId: {
+              type: "string",
+              description: "mNNNNN ref at the start of the range",
+            },
+            endId: {
+              type: "string",
+              description: "mNNNNN ref at the end of the range",
+            },
+            summary: {
+              type: "string",
+              description: "Self-contained summary replacing the range",
+            },
+          },
+          required: ["startId", "endId", "summary"],
+        },
+      },
+    },
+    required: ["content"],
+  },
+};
+
+export const DECOMPRESS_TOOL_GOOGLE = {
+  name: DECOMPRESS_TOOL_NAME,
+  description: DECOMPRESS_TOOL_OPENAI.function.description,
+  parameters: DECOMPRESS_TOOL_OPENAI.function.parameters,
+};
+
+export const SEARCH_CONTEXT_TOOL_GOOGLE = {
+  name: SEARCH_CONTEXT_TOOL_NAME,
+  description: SEARCH_CONTEXT_TOOL_OPENAI.function.description,
+  parameters: SEARCH_CONTEXT_TOOL_OPENAI.function.parameters,
+};
+
+export const ACP_STATUS_TOOL_GOOGLE = {
+  name: ACP_STATUS_TOOL_NAME,
+  description: ACP_STATUS_TOOL_OPENAI.function.description,
+  parameters: ACP_STATUS_TOOL_OPENAI.function.parameters,
+};
+
+/** All ACP tools in Gemini flat format, matching ACP_TOOL_NAMES. */
+export const ACP_TOOLS_GOOGLE = [
+  COMPRESS_TOOL_GOOGLE,
+  DECOMPRESS_TOOL_GOOGLE,
+  SEARCH_CONTEXT_TOOL_GOOGLE,
+  ACP_STATUS_TOOL_GOOGLE,
+] as const;
+
+/** Opt-in absorb tool in Gemini flat format (config.absorb.enabled). */
+export const ABSORB_TOOL_GOOGLE = {
+  name: ABSORB_TOOL_NAME,
+  description: ABSORB_TOOL_DESCRIPTION,
+  parameters: ABSORB_PARAMETERS,
+};

src/wire/bili-message.ts

@@ -34,10 +34,20 @@ export interface BiliMessage extends CoreMessage {
     /** Responses API: the original input item (for input_image, or a raw
      *  function_call / function_call_output we pass through). */
     rawResponsesItem?: unknown;
+    /** Google/Gemini: the original content parts of this message, in wire
+     *  order (inlineData/fileData, executableCode, functionCall/Response ids,
+     *  thought parts and unknown future part types). coreToGoogle rebuilds
+     *  the content from these when present, so parts the core does not model
+     *  survive a round-trip. */
+    rawGoogleParts?: unknown[];
     /** Anthropic thinking signature. Anthropic verifies thinking+signature
      *  pairs; without it the request is rejected. Stored alongside the
      *  reasoning text so coreToAnthropic can reattach it. */
     thinkingSignature?: string;
+    /** Google/Gemini thought signature (thoughtSignature). Gemini 3 validates
+     *  the signature of every replayed thought part, so a reasoning core
+     *  carries it here for coreToGoogle to reattach. */
+    googleThoughtSignature?: string;
     /** OpenAI reasoning_content (chain-of-thought from DeepSeek-R1, GLM-4.6
      *  thinking, Qwen-QwQ). These models require reasoning_content be echoed
      *  back on subsequent requests or the API returns HTTP 400; stored so

src/wire/formats.ts

@@ -1,4 +1,4 @@
-export const WIRE_FORMATS = ["anthropic", "openai", "responses"] as const;
+export const WIRE_FORMATS = ["anthropic", "openai", "responses", "google"] as const;
 export type WireFormat = (typeof WIRE_FORMATS)[number];
 
 export function isWireFormat(value: unknown): value is WireFormat {
@@ -16,6 +16,9 @@ export function isWireFormat(value: unknown): value is WireFormat {
 export function detectWireFormat(payload: unknown): WireFormat | undefined {
   if (payload === null || typeof payload !== "object") return undefined;
   const p = payload as Record<string, unknown>;
+  // Gemini native carries the conversation in `contents`; no other dialect
+  // does, and it never has `input`/`messages`, so the check is unambiguous.
+  if (Array.isArray(p.contents)) return "google";
   if (Array.isArray(p.input)) return "responses";
   const messages = p.messages;
   if (!Array.isArray(messages)) return undefined;