Agents: sanitize OpenRouter Gemini thoughtSignature

CHANGELOG.md

@@ -143,6 +143,7 @@
 ### Fixes
 - Packaging: include `dist/memory/**` in the npm tarball (fixes `ERR_MODULE_NOT_FOUND` for `dist/memory/index.js`).
 - Agents: persist sub-agent registry across gateway restarts and resume announce flow safely. (#831) — thanks @roshanasingh4.
+- Agents: strip invalid Gemini thought signatures from OpenRouter history to avoid 400s. (#841)
 
 ## 2026.1.12-1
 

src/agents/pi-embedded-helpers.test.ts

@@ -0,0 +1,755 @@
+import type { AgentMessage } from "@mariozechner/pi-agent-core";
+import type { AssistantMessage } from "@mariozechner/pi-ai";
+import { describe, expect, it } from "vitest";
+import type { ClawdbotConfig } from "../config/config.js";
+import {
+  buildBootstrapContextFiles,
+  classifyFailoverReason,
+  DEFAULT_BOOTSTRAP_MAX_CHARS,
+  formatAssistantErrorText,
+  isAuthErrorMessage,
+  isBillingErrorMessage,
+  isCloudCodeAssistFormatError,
+  isCompactionFailureError,
+  isContextOverflowError,
+  isFailoverErrorMessage,
+  isMessagingToolDuplicate,
+  normalizeTextForComparison,
+  resolveBootstrapMaxChars,
+  sanitizeGoogleTurnOrdering,
+  sanitizeSessionMessagesImages,
+  sanitizeToolCallId,
+  stripThoughtSignatures,
+} from "./pi-embedded-helpers.js";
+import {
+  DEFAULT_AGENTS_FILENAME,
+  type WorkspaceBootstrapFile,
+} from "./workspace.js";
+
+const makeFile = (
+  overrides: Partial<WorkspaceBootstrapFile>,
+): WorkspaceBootstrapFile => ({
+  name: DEFAULT_AGENTS_FILENAME,
+  path: "/tmp/AGENTS.md",
+  content: "",
+  missing: false,
+  ...overrides,
+});
+describe("buildBootstrapContextFiles", () => {
+  it("keeps missing markers", () => {
+    const files = [makeFile({ missing: true, content: undefined })];
+    expect(buildBootstrapContextFiles(files)).toEqual([
+      {
+        path: DEFAULT_AGENTS_FILENAME,
+        content: "[MISSING] Expected at: /tmp/AGENTS.md",
+      },
+    ]);
+  });
+
+  it("skips empty or whitespace-only content", () => {
+    const files = [makeFile({ content: "   \n  " })];
+    expect(buildBootstrapContextFiles(files)).toEqual([]);
+  });
+
+  it("truncates large bootstrap content", () => {
+    const head = `HEAD-${"a".repeat(600)}`;
+    const tail = `${"b".repeat(300)}-TAIL`;
+    const long = `${head}${tail}`;
+    const files = [makeFile({ name: "TOOLS.md", content: long })];
+    const warnings: string[] = [];
+    const maxChars = 200;
+    const expectedTailChars = Math.floor(maxChars * 0.2);
+    const [result] = buildBootstrapContextFiles(files, {
+      maxChars,
+      warn: (message) => warnings.push(message),
+    });
+    expect(result?.content).toContain(
+      "[...truncated, read TOOLS.md for full content...]",
+    );
+    expect(result?.content.length).toBeLessThan(long.length);
+    expect(result?.content.startsWith(long.slice(0, 120))).toBe(true);
+    expect(result?.content.endsWith(long.slice(-expectedTailChars))).toBe(true);
+    expect(warnings).toHaveLength(1);
+    expect(warnings[0]).toContain("TOOLS.md");
+    expect(warnings[0]).toContain("limit 200");
+  });
+
+  it("keeps content under the default limit", () => {
+    const long = "a".repeat(DEFAULT_BOOTSTRAP_MAX_CHARS - 10);
+    const files = [makeFile({ content: long })];
+    const [result] = buildBootstrapContextFiles(files);
+    expect(result?.content).toBe(long);
+    expect(result?.content).not.toContain(
+      "[...truncated, read AGENTS.md for full content...]",
+    );
+  });
+});
+
+describe("resolveBootstrapMaxChars", () => {
+  it("returns default when unset", () => {
+    expect(resolveBootstrapMaxChars()).toBe(DEFAULT_BOOTSTRAP_MAX_CHARS);
+  });
+
+  it("uses configured value when valid", () => {
+    const cfg = {
+      agents: { defaults: { bootstrapMaxChars: 12345 } },
+    } as ClawdbotConfig;
+    expect(resolveBootstrapMaxChars(cfg)).toBe(12345);
+  });
+
+  it("falls back when invalid", () => {
+    const cfg = {
+      agents: { defaults: { bootstrapMaxChars: -1 } },
+    } as ClawdbotConfig;
+    expect(resolveBootstrapMaxChars(cfg)).toBe(DEFAULT_BOOTSTRAP_MAX_CHARS);
+  });
+});
+
+describe("isContextOverflowError", () => {
+  it("matches known overflow hints", () => {
+    const samples = [
+      "request_too_large",
+      "Request exceeds the maximum size",
+      "context length exceeded",
+      "Maximum context length",
+      "prompt is too long: 208423 tokens > 200000 maximum",
+      "Context overflow: Summarization failed",
+      "413 Request Entity Too Large",
+    ];
+    for (const sample of samples) {
+      expect(isContextOverflowError(sample)).toBe(true);
+    }
+  });
+
+  it("ignores unrelated errors", () => {
+    expect(isContextOverflowError("rate limit exceeded")).toBe(false);
+  });
+});
+
+describe("isCompactionFailureError", () => {
+  it("matches compaction overflow failures", () => {
+    const samples = [
+      'Context overflow: Summarization failed: 400 {"message":"prompt is too long"}',
+      "auto-compaction failed due to context overflow",
+      "Compaction failed: prompt is too long",
+    ];
+    for (const sample of samples) {
+      expect(isCompactionFailureError(sample)).toBe(true);
+    }
+  });
+
+  it("ignores non-compaction overflow errors", () => {
+    expect(isCompactionFailureError("Context overflow: prompt too large")).toBe(
+      false,
+    );
+    expect(isCompactionFailureError("rate limit exceeded")).toBe(false);
+  });
+});
+
+describe("isBillingErrorMessage", () => {
+  it("matches credit / payment failures", () => {
+    const samples = [
+      "Your credit balance is too low to access the Anthropic API.",
+      "insufficient credits",
+      "Payment Required",
+      "HTTP 402 Payment Required",
+      "plans & billing",
+      "billing: please upgrade your plan",
+    ];
+    for (const sample of samples) {
+      expect(isBillingErrorMessage(sample)).toBe(true);
+    }
+  });
+
+  it("ignores unrelated errors", () => {
+    expect(isBillingErrorMessage("rate limit exceeded")).toBe(false);
+    expect(isBillingErrorMessage("invalid api key")).toBe(false);
+    expect(isBillingErrorMessage("context length exceeded")).toBe(false);
+  });
+});
+
+describe("isAuthErrorMessage", () => {
+  it("matches credential validation errors", () => {
+    const samples = [
+      'No credentials found for profile "anthropic:claude-cli".',
+      "No API key found for profile openai.",
+    ];
+    for (const sample of samples) {
+      expect(isAuthErrorMessage(sample)).toBe(true);
+    }
+  });
+
+  it("ignores unrelated errors", () => {
+    expect(isAuthErrorMessage("rate limit exceeded")).toBe(false);
+    expect(isAuthErrorMessage("billing issue detected")).toBe(false);
+  });
+});
+
+describe("isFailoverErrorMessage", () => {
+  it("matches auth/rate/billing/timeout", () => {
+    const samples = [
+      "invalid api key",
+      "429 rate limit exceeded",
+      "Your credit balance is too low",
+      "request timed out",
+      "invalid request format",
+    ];
+    for (const sample of samples) {
+      expect(isFailoverErrorMessage(sample)).toBe(true);
+    }
+  });
+});
+
+describe("classifyFailoverReason", () => {
+  it("returns a stable reason", () => {
+    expect(classifyFailoverReason("invalid api key")).toBe("auth");
+    expect(classifyFailoverReason("no credentials found")).toBe("auth");
+    expect(classifyFailoverReason("no api key found")).toBe("auth");
+    expect(classifyFailoverReason("429 too many requests")).toBe("rate_limit");
+    expect(classifyFailoverReason("resource has been exhausted")).toBe(
+      "rate_limit",
+    );
+    expect(
+      classifyFailoverReason(
+        '{"type":"error","error":{"type":"overloaded_error","message":"Overloaded"}}',
+      ),
+    ).toBe("rate_limit");
+    expect(classifyFailoverReason("invalid request format")).toBe("format");
+    expect(classifyFailoverReason("credit balance too low")).toBe("billing");
+    expect(classifyFailoverReason("deadline exceeded")).toBe("timeout");
+    expect(classifyFailoverReason("string should match pattern")).toBe(
+      "format",
+    );
+    expect(classifyFailoverReason("bad request")).toBeNull();
+  });
+
+  it("classifies OpenAI usage limit errors as rate_limit", () => {
+    expect(
+      classifyFailoverReason(
+        "You have hit your ChatGPT usage limit (plus plan)",
+      ),
+    ).toBe("rate_limit");
+  });
+});
+
+describe("isCloudCodeAssistFormatError", () => {
+  it("matches format errors", () => {
+    const samples = [
+      "INVALID_REQUEST_ERROR: string should match pattern",
+      "messages.1.content.1.tool_use.id",
+      "tool_use.id should match pattern",
+      "invalid request format",
+    ];
+    for (const sample of samples) {
+      expect(isCloudCodeAssistFormatError(sample)).toBe(true);
+    }
+  });
+
+  it("ignores unrelated errors", () => {
+    expect(isCloudCodeAssistFormatError("rate limit exceeded")).toBe(false);
+  });
+});
+
+describe("formatAssistantErrorText", () => {
+  const makeAssistantError = (errorMessage: string): AssistantMessage =>
+    ({
+      stopReason: "error",
+      errorMessage,
+    }) as AssistantMessage;
+
+  it("returns a friendly message for context overflow", () => {
+    const msg = makeAssistantError("request_too_large");
+    expect(formatAssistantErrorText(msg)).toContain("Context overflow");
+  });
+
+  it("returns a friendly message for Anthropic role ordering", () => {
+    const msg = makeAssistantError(
+      'messages: roles must alternate between "user" and "assistant"',
+    );
+    expect(formatAssistantErrorText(msg)).toContain(
+      "Message ordering conflict",
+    );
+  });
+
+  it("returns a friendly message for Anthropic overload errors", () => {
+    const msg = makeAssistantError(
+      '{"type":"error","error":{"details":null,"type":"overloaded_error","message":"Overloaded"},"request_id":"req_123"}',
+    );
+    expect(formatAssistantErrorText(msg)).toBe(
+      "The AI service is temporarily overloaded. Please try again in a moment.",
+    );
+  });
+});
+
+describe("sanitizeToolCallId", () => {
+  it("keeps valid tool call IDs", () => {
+    expect(sanitizeToolCallId("call_abc-123")).toBe("call_abc-123");
+  });
+
+  it("replaces invalid characters with underscores", () => {
+    expect(sanitizeToolCallId("call_abc|item:456")).toBe("call_abc_item_456");
+  });
+
+  it("returns default for empty IDs", () => {
+    expect(sanitizeToolCallId("")).toBe("default_tool_id");
+  });
+});
+
+describe("sanitizeGoogleTurnOrdering", () => {
+  it("prepends a synthetic user turn when history starts with assistant", () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          { type: "toolCall", id: "call_1", name: "exec", arguments: {} },
+        ],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = sanitizeGoogleTurnOrdering(input);
+    expect(out[0]?.role).toBe("user");
+    expect(out[1]?.role).toBe("assistant");
+  });
+
+  it("is a no-op when history starts with user", () => {
+    const input = [{ role: "user", content: "hi" }] satisfies AgentMessage[];
+    const out = sanitizeGoogleTurnOrdering(input);
+    expect(out).toBe(input);
+  });
+});
+
+describe("sanitizeSessionMessagesImages", () => {
+  it("removes empty assistant text blocks but preserves tool calls", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "" },
+          { type: "toolCall", id: "call_1", name: "read", arguments: {} },
+        ],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(1);
+    const content = (out[0] as { content?: unknown }).content;
+    expect(Array.isArray(content)).toBe(true);
+    expect(content).toHaveLength(1);
+    expect((content as Array<{ type?: string }>)[0]?.type).toBe("toolCall");
+  });
+
+  it("sanitizes tool ids for assistant blocks and tool results when enabled", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          { type: "toolUse", id: "call_abc|item:123", name: "test", input: {} },
+          {
+            type: "toolCall",
+            id: "call_abc|item:456",
+            name: "exec",
+            arguments: {},
+          },
+        ],
+      },
+      {
+        role: "toolResult",
+        toolUseId: "call_abc|item:123",
+        content: [{ type: "text", text: "ok" }],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test", {
+      sanitizeToolCallIds: true,
+    });
+
+    const assistant = out[0] as { content?: Array<{ id?: string }> };
+    expect(assistant.content?.[0]?.id).toBe("call_abc_item_123");
+    expect(assistant.content?.[1]?.id).toBe("call_abc_item_456");
+
+    const toolResult = out[1] as { toolUseId?: string };
+    expect(toolResult.toolUseId).toBe("call_abc_item_123");
+  });
+
+  it("filters whitespace-only assistant text blocks", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "   " },
+          { type: "text", text: "ok" },
+        ],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(1);
+    const content = (out[0] as { content?: unknown }).content;
+    expect(Array.isArray(content)).toBe(true);
+    expect(content).toHaveLength(1);
+    expect((content as Array<{ text?: string }>)[0]?.text).toBe("ok");
+  });
+
+  it("drops assistant messages that only contain empty text", async () => {
+    const input = [
+      { role: "user", content: "hello" },
+      { role: "assistant", content: [{ type: "text", text: "" }] },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(1);
+    expect(out[0]?.role).toBe("user");
+  });
+
+  it("drops empty assistant error messages", async () => {
+    const input = [
+      { role: "user", content: "hello" },
+      { role: "assistant", stopReason: "error", content: [] },
+      { role: "assistant", stopReason: "error" },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(1);
+    expect(out[0]?.role).toBe("user");
+  });
+
+  it("leaves non-assistant messages unchanged", async () => {
+    const input = [
+      { role: "user", content: "hello" },
+      {
+        role: "toolResult",
+        toolCallId: "tool-1",
+        content: [{ type: "text", text: "result" }],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(2);
+    expect(out[0]?.role).toBe("user");
+    expect(out[1]?.role).toBe("toolResult");
+  });
+
+  it("keeps tool call + tool result IDs unchanged by default", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          {
+            type: "toolCall",
+            id: "call_123|fc_456",
+            name: "read",
+            arguments: { path: "package.json" },
+          },
+        ],
+      },
+      {
+        role: "toolResult",
+        toolCallId: "call_123|fc_456",
+        toolName: "read",
+        content: [{ type: "text", text: "ok" }],
+        isError: false,
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    const assistant = out[0] as unknown as { role?: string; content?: unknown };
+    expect(assistant.role).toBe("assistant");
+    expect(Array.isArray(assistant.content)).toBe(true);
+    const toolCall = (
+      assistant.content as Array<{ type?: string; id?: string }>
+    ).find((b) => b.type === "toolCall");
+    expect(toolCall?.id).toBe("call_123|fc_456");
+
+    const toolResult = out[1] as unknown as {
+      role?: string;
+      toolCallId?: string;
+    };
+    expect(toolResult.role).toBe("toolResult");
+    expect(toolResult.toolCallId).toBe("call_123|fc_456");
+  });
+
+  it("sanitizes tool call + tool result IDs when enabled", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          {
+            type: "toolCall",
+            id: "call_123|fc_456",
+            name: "read",
+            arguments: { path: "package.json" },
+          },
+        ],
+      },
+      {
+        role: "toolResult",
+        toolCallId: "call_123|fc_456",
+        toolName: "read",
+        content: [{ type: "text", text: "ok" }],
+        isError: false,
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test", {
+      sanitizeToolCallIds: true,
+    });
+
+    const assistant = out[0] as unknown as { role?: string; content?: unknown };
+    expect(assistant.role).toBe("assistant");
+    expect(Array.isArray(assistant.content)).toBe(true);
+    const toolCall = (
+      assistant.content as Array<{ type?: string; id?: string }>
+    ).find((b) => b.type === "toolCall");
+    expect(toolCall?.id).toBe("call_123_fc_456");
+
+    const toolResult = out[1] as unknown as {
+      role?: string;
+      toolCallId?: string;
+    };
+    expect(toolResult.role).toBe("toolResult");
+    expect(toolResult.toolCallId).toBe("call_123_fc_456");
+  });
+
+  it("drops assistant blocks after a tool call when enforceToolCallLast is enabled", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "before" },
+          { type: "toolCall", id: "call_1", name: "read", arguments: {} },
+          { type: "thinking", thinking: "after", thinkingSignature: "sig" },
+          { type: "text", text: "after text" },
+        ],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test", {
+      enforceToolCallLast: true,
+    });
+    const assistant = out[0] as { content?: Array<{ type?: string }> };
+    expect(assistant.content?.map((b) => b.type)).toEqual(["text", "toolCall"]);
+  });
+
+  it("keeps assistant blocks after a tool call when enforceToolCallLast is disabled", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "before" },
+          { type: "toolCall", id: "call_1", name: "read", arguments: {} },
+          { type: "thinking", thinking: "after", thinkingSignature: "sig" },
+          { type: "text", text: "after text" },
+        ],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+    const assistant = out[0] as { content?: Array<{ type?: string }> };
+    expect(assistant.content?.map((b) => b.type)).toEqual([
+      "text",
+      "toolCall",
+      "thinking",
+      "text",
+    ]);
+  });
+});
+
+describe("normalizeTextForComparison", () => {
+  it("lowercases text", () => {
+    expect(normalizeTextForComparison("Hello World")).toBe("hello world");
+  });
+
+  it("trims whitespace", () => {
+    expect(normalizeTextForComparison("  hello  ")).toBe("hello");
+  });
+
+  it("collapses multiple spaces", () => {
+    expect(normalizeTextForComparison("hello    world")).toBe("hello world");
+  });
+
+  it("strips emoji", () => {
+    expect(normalizeTextForComparison("Hello 👋 World 🌍")).toBe("hello world");
+  });
+
+  it("handles mixed normalization", () => {
+    expect(normalizeTextForComparison("  Hello 👋   WORLD  🌍  ")).toBe(
+      "hello world",
+    );
+  });
+});
+
+describe("stripThoughtSignatures", () => {
+  it("returns non-array content unchanged", () => {
+    expect(stripThoughtSignatures("hello")).toBe("hello");
+    expect(stripThoughtSignatures(null)).toBe(null);
+    expect(stripThoughtSignatures(undefined)).toBe(undefined);
+    expect(stripThoughtSignatures(123)).toBe(123);
+  });
+
+  it("removes msg_-prefixed thought_signature from content blocks", () => {
+    const input = [
+      { type: "text", text: "hello", thought_signature: "msg_abc123" },
+      { type: "thinking", thinking: "test", thought_signature: "AQID" },
+    ];
+    const result = stripThoughtSignatures(input);
+
+    expect(result).toHaveLength(2);
+    expect(result[0]).toEqual({ type: "text", text: "hello" });
+    expect(result[1]).toEqual({
+      type: "thinking",
+      thinking: "test",
+      thought_signature: "AQID",
+    });
+    expect("thought_signature" in result[0]).toBe(false);
+    expect("thought_signature" in result[1]).toBe(true);
+  });
+
+  it("preserves blocks without thought_signature", () => {
+    const input = [
+      { type: "text", text: "hello" },
+      { type: "toolCall", id: "call_1", name: "read", arguments: {} },
+    ];
+    const result = stripThoughtSignatures(input);
+
+    expect(result).toEqual(input);
+  });
+
+  it("handles mixed blocks with and without thought_signature", () => {
+    const input = [
+      { type: "text", text: "hello", thought_signature: "msg_abc" },
+      { type: "toolCall", id: "call_1", name: "read", arguments: {} },
+      { type: "thinking", thinking: "hmm", thought_signature: "msg_xyz" },
+    ];
+    const result = stripThoughtSignatures(input);
+
+    expect(result).toEqual([
+      { type: "text", text: "hello" },
+      { type: "toolCall", id: "call_1", name: "read", arguments: {} },
+      { type: "thinking", thinking: "hmm" },
+    ]);
+  });
+
+  it("handles empty array", () => {
+    expect(stripThoughtSignatures([])).toEqual([]);
+  });
+
+  it("handles null/undefined blocks in array", () => {
+    const input = [null, undefined, { type: "text", text: "hello" }];
+    const result = stripThoughtSignatures(input);
+    expect(result).toEqual([null, undefined, { type: "text", text: "hello" }]);
+  });
+
+  it("strips non-base64 thought signatures when configured for Gemini", () => {
+    const input = [
+      { type: "text", text: "hello", thought_signature: "msg_abc123" },
+      { type: "thinking", thinking: "ok", thought_signature: "c2ln" },
+      { type: "toolCall", id: "call_1", thoughtSignature: '{"id":1}' },
+      { type: "toolCall", id: "call_2", thoughtSignature: "c2ln" },
+    ];
+
+    const result = stripThoughtSignatures(input, {
+      allowBase64Only: true,
+      includeCamelCase: true,
+    });
+
+    expect(result).toEqual([
+      { type: "text", text: "hello" },
+      { type: "thinking", thinking: "ok", thought_signature: "c2ln" },
+      { type: "toolCall", id: "call_1" },
+      { type: "toolCall", id: "call_2", thoughtSignature: "c2ln" },
+    ]);
+  });
+});
+
+describe("sanitizeSessionMessagesImages - thought_signature stripping", () => {
+  it("strips msg_-prefixed thought_signature from assistant message content blocks", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "hello", thought_signature: "msg_abc123" },
+          {
+            type: "thinking",
+            thinking: "reasoning",
+            thought_signature: "AQID",
+          },
+        ],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(1);
+    const content = (out[0] as { content?: unknown[] }).content;
+    expect(content).toHaveLength(2);
+    expect("thought_signature" in ((content?.[0] ?? {}) as object)).toBe(false);
+    expect(
+      (content?.[1] as { thought_signature?: unknown })?.thought_signature,
+    ).toBe("AQID");
+  });
+});
+
+describe("isMessagingToolDuplicate", () => {
+  it("returns false for empty sentTexts", () => {
+    expect(isMessagingToolDuplicate("hello world", [])).toBe(false);
+  });
+
+  it("returns false for short texts", () => {
+    expect(isMessagingToolDuplicate("short", ["short"])).toBe(false);
+  });
+
+  it("detects exact duplicates", () => {
+    expect(
+      isMessagingToolDuplicate("Hello, this is a test message!", [
+        "Hello, this is a test message!",
+      ]),
+    ).toBe(true);
+  });
+
+  it("detects duplicates with different casing", () => {
+    expect(
+      isMessagingToolDuplicate("HELLO, THIS IS A TEST MESSAGE!", [
+        "hello, this is a test message!",
+      ]),
+    ).toBe(true);
+  });
+
+  it("detects duplicates with emoji variations", () => {
+    expect(
+      isMessagingToolDuplicate("Hello! 👋 This is a test message!", [
+        "Hello! This is a test message!",
+      ]),
+    ).toBe(true);
+  });
+
+  it("detects substring duplicates (LLM elaboration)", () => {
+    expect(
+      isMessagingToolDuplicate(
+        'I sent the message: "Hello, this is a test message!"',
+        ["Hello, this is a test message!"],
+      ),
+    ).toBe(true);
+  });
+
+  it("detects when sent text contains block reply (reverse substring)", () => {
+    expect(
+      isMessagingToolDuplicate("Hello, this is a test message!", [
+        'I sent the message: "Hello, this is a test message!"',
+      ]),
+    ).toBe(true);
+  });
+
+  it("returns false for non-matching texts", () => {
+    expect(
+      isMessagingToolDuplicate("This is completely different content.", [
+        "Hello, this is a test message!",
+      ]),
+    ).toBe(false);
+  });
+});

src/agents/pi-embedded-helpers/bootstrap.ts

@@ -9,26 +9,65 @@ import type { EmbeddedContextFile } from "./types.js";
 
 type ContentBlockWithSignature = {
   thought_signature?: unknown;
+  thoughtSignature?: unknown;
   [key: string]: unknown;
 };
 
+type ThoughtSignatureSanitizeOptions = {
+  allowBase64Only?: boolean;
+  includeCamelCase?: boolean;
+};
+
+function isBase64Signature(value: string): boolean {
+  const trimmed = value.trim();
+  if (!trimmed) return false;
+  const compact = trimmed.replace(/\s+/g, "");
+  if (!/^[A-Za-z0-9+/=_-]+$/.test(compact)) return false;
+  const isUrl = compact.includes("-") || compact.includes("_");
+  try {
+    const buf = Buffer.from(compact, isUrl ? "base64url" : "base64");
+    if (buf.length === 0) return false;
+    const encoded = buf.toString(isUrl ? "base64url" : "base64");
+    const normalize = (input: string) => input.replace(/=+$/g, "");
+    return normalize(encoded) === normalize(compact);
+  } catch {
+    return false;
+  }
+}
+
 /**
  * Strips Claude-style thought_signature fields from content blocks.
  *
  * Gemini expects thought signatures as base64-encoded bytes, but Claude stores message ids
  * like "msg_abc123...". We only strip "msg_*" to preserve any provider-valid signatures.
  */
-export function stripThoughtSignatures<T>(content: T): T {
+export function stripThoughtSignatures<T>(
+  content: T,
+  options?: ThoughtSignatureSanitizeOptions,
+): T {
   if (!Array.isArray(content)) return content;
+  const allowBase64Only = options?.allowBase64Only ?? false;
+  const includeCamelCase = options?.includeCamelCase ?? false;
+  const shouldStripSignature = (value: unknown): boolean => {
+    if (!allowBase64Only) {
+      return typeof value === "string" && value.startsWith("msg_");
+    }
+    return typeof value !== "string" || !isBase64Signature(value);
+  };
   return content.map((block) => {
     if (!block || typeof block !== "object") return block;
     const rec = block as ContentBlockWithSignature;
-    const signature = rec.thought_signature;
+    const stripSnake = shouldStripSignature(rec.thought_signature);
-    if (typeof signature !== "string" || !signature.startsWith("msg_")) {
+    const stripCamel = includeCamelCase
+      ? shouldStripSignature(rec.thoughtSignature)
+      : false;
+    if (!stripSnake && !stripCamel) {
       return block;
     }
-    const { thought_signature: _signature, ...rest } = rec;
+    const next = { ...rec };
-    return rest;
+    if (stripSnake) delete next.thought_signature;
+    if (stripCamel) delete next.thoughtSignature;
+    return next;
   }) as T;
 }
 

src/agents/pi-embedded-helpers/google.ts

@@ -23,6 +23,7 @@ export { sanitizeGoogleTurnOrdering };
 type GeminiToolCallBlock = {
   type?: unknown;
   thought_signature?: unknown;
+  thoughtSignature?: unknown;
   id?: unknown;
   toolCallId?: unknown;
   name?: unknown;
@@ -118,7 +119,8 @@ export function downgradeGeminiHistory(messages: AgentMessage[]): AgentMessage[]
         const blockRecord = block as GeminiToolCallBlock;
         const type = blockRecord.type;
         if (type === "toolCall" || type === "functionCall" || type === "toolUse") {
-          const hasSignature = Boolean(blockRecord.thought_signature);
+          const signature = blockRecord.thought_signature ?? blockRecord.thoughtSignature;
+          const hasSignature = Boolean(signature);
           if (!hasSignature) {
             const id =
               typeof blockRecord.id === "string"

src/agents/pi-embedded-helpers/images.ts

@@ -34,6 +34,10 @@ export async function sanitizeSessionMessagesImages(
     sanitizeToolCallIds?: boolean;
     enforceToolCallLast?: boolean;
     preserveSignatures?: boolean;
+    sanitizeThoughtSignatures?: {
+      allowBase64Only?: boolean;
+      includeCamelCase?: boolean;
+    };
   },
 ): Promise<AgentMessage[]> {
   // We sanitize historical session messages because Anthropic can reject a request
@@ -82,7 +86,7 @@ export async function sanitizeSessionMessagesImages(
       if (Array.isArray(content)) {
         const strippedContent = options?.preserveSignatures
           ? content // Keep signatures for Antigravity Claude
-          : stripThoughtSignatures(content); // Strip for Gemini
+          : stripThoughtSignatures(content, options?.sanitizeThoughtSignatures); // Strip for Gemini
 
         const filteredContent = strippedContent.filter((block) => {
           if (!block || typeof block !== "object") return true;

src/agents/pi-embedded-runner.google-sanitize-thinking.test.ts

@@ -145,6 +145,44 @@ describe("sanitizeSessionHistory (google thinking)", () => {
     expect(assistant.content?.[1]?.text).toBe("internal note");
   });
 
+  it("strips non-base64 thought signatures for OpenRouter Gemini", async () => {
+    const sessionManager = SessionManager.inMemory();
+    const input = [
+      {
+        role: "user",
+        content: "hi",
+      },
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "hello", thought_signature: "msg_abc123" },
+          { type: "thinking", thinking: "ok", thought_signature: "c2ln" },
+          { type: "toolCall", id: "call_1", thoughtSignature: "{\"id\":1}" },
+          { type: "toolCall", id: "call_2", thoughtSignature: "c2ln" },
+        ],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionHistory({
+      messages: input,
+      modelApi: "openrouter",
+      provider: "openrouter",
+      modelId: "google/gemini-1.5-pro",
+      sessionManager,
+      sessionId: "session:openrouter-gemini",
+    });
+
+    const assistant = out.find((msg) => (msg as { role?: string }).role === "assistant") as {
+      content?: Array<{ type?: string; thought_signature?: string; thoughtSignature?: string }>;
+    };
+    expect(assistant.content).toEqual([
+      { type: "text", text: "hello" },
+      { type: "thinking", thinking: "ok", thought_signature: "c2ln" },
+      { type: "toolCall", id: "call_1" },
+      { type: "toolCall", id: "call_2", thoughtSignature: "c2ln" },
+    ]);
+  });
+
   it("downgrades only unsigned thinking blocks when mixed with signed ones", async () => {
     const sessionManager = SessionManager.inMemory();
     const input = [

src/agents/pi-embedded-runner/compact.ts

@@ -308,6 +308,7 @@ export async function compactEmbeddedPiSession(params: {
               messages: session.messages,
               modelApi: model.api,
               modelId,
+              provider,
               sessionManager,
               sessionId: params.sessionId,
             });

src/agents/pi-embedded-runner/google.ts

@@ -185,17 +185,26 @@ export async function sanitizeSessionHistory(params: {
   messages: AgentMessage[];
   modelApi?: string | null;
   modelId?: string;
+  provider?: string;
   sessionManager: SessionManager;
   sessionId: string;
 }): Promise<AgentMessage[]> {
   const isAntigravityClaudeModel = isAntigravityClaude(params.modelApi, params.modelId);
+  const provider = (params.provider ?? "").toLowerCase();
+  const modelId = (params.modelId ?? "").toLowerCase();
+  const isOpenRouterGemini =
+    (provider === "openrouter" || provider === "opencode") && modelId.includes("gemini");
+  const isGeminiLike = isGoogleModelApi(params.modelApi) || isOpenRouterGemini;
   const sanitizedImages = await sanitizeSessionMessagesImages(params.messages, "session:history", {
     sanitizeToolCallIds: shouldSanitizeToolCallIds(params.modelApi),
     enforceToolCallLast: params.modelApi === "anthropic-messages",
     preserveSignatures: params.modelApi === "google-antigravity" && isAntigravityClaudeModel,
+    sanitizeThoughtSignatures: isOpenRouterGemini
+      ? { allowBase64Only: true, includeCamelCase: true }
+      : undefined,
   });
   const repairedTools = sanitizeToolUseResultPairing(sanitizedImages);
-  const shouldDowngradeGemini = isGoogleModelApi(params.modelApi) && !isAntigravityClaudeModel;
+  const shouldDowngradeGemini = isGeminiLike && !isAntigravityClaudeModel;
   // Gemini rejects unsigned thinking blocks; downgrade them before send to avoid INVALID_ARGUMENT.
   const downgradedThinking = shouldDowngradeGemini
     ? downgradeGeminiThinkingBlocks(repairedTools)

src/agents/pi-embedded-runner/run/attempt.ts

@@ -323,6 +323,7 @@ export async function runEmbeddedAttempt(
           messages: activeSession.messages,
           modelApi: params.model.api,
           modelId: params.modelId,
+          provider: params.provider,
           sessionManager,
           sessionId: params.sessionId,
         });