feat(FN-3855): bypass send-message binding in gate wrappers

- Remove hard dependency on sendMessage in pi agent wrappers so no-approval gates can run without chat bindings
- Add regression coverage for createFnAgent behavior when sendMessage is absent and when tool calls still execute
- Add changeset for @runfusion/fusion documenting the no-approval gate send-message fix

Fusion-Task-Id: FN-3855

.changeset/fn-3855-no-approval-gate-send-message.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": patch
+---
+
+Agent messaging via `fn_send_message` can no longer be deadlocked by an approval policy interposing on it. The messaging primitive now bypasses both the action gate and the permanent-agent gate by reference, so even a misconfigured policy or classification-table regression cannot strand inter-agent coordination, wake-on-message replies, or agent-to-user escalations. No user-visible behavior change for correctly classified deployments.

packages/engine/src/__tests__/pi-create-fn-agent.test.ts

@@ -557,6 +557,46 @@ describe("wrapToolsWithPermanentAgentGating", () => {
     expect(createApprovalRequest).not.toHaveBeenCalled();
     expect(findPendingApprovalRequest).not.toHaveBeenCalled();
   });
+
+  it.each<[
+    "locked-down" | "approval-required",
+    Record<string, "block" | "require-approval">
+  ]>([
+    ["locked-down", {
+      git_write: "block",
+      file_write_delete: "block",
+      command_execution: "block",
+      network_api: "block",
+      task_agent_mutation: "block",
+    }],
+    ["approval-required", {
+      git_write: "require-approval",
+      file_write_delete: "require-approval",
+      command_execution: "require-approval",
+      network_api: "require-approval",
+      task_agent_mutation: "require-approval",
+    }],
+  ])("bypasses wrapping for fn_send_message under %s policy", async (presetId, rules) => {
+    const args = { message: "ping" };
+    const result = { ok: true, messageId: "msg-1" };
+    const execute = vi.fn().mockResolvedValue(result);
+    const tool = { name: "fn_send_message", label: "Send Message", description: "", parameters: {}, execute };
+    const createApprovalRequest = vi.fn();
+    const findPendingApprovalRequest = vi.fn();
+    const { wrapToolsWithPermanentAgentGating } = await import("../pi.js");
+    const wrapped = wrapToolsWithPermanentAgentGating([tool as any], {
+      permissionPolicy: { presetId, rules },
+      createApprovalRequest,
+      findPendingApprovalRequest,
+    });
+
+    expect(wrapped[0]).toBe(tool);
+    await expect((wrapped[0] as any).execute("t1", args)).resolves.toEqual(result);
+    expect(execute).toHaveBeenCalledTimes(1);
+    expect(execute).toHaveBeenCalledWith("t1", args);
+    expect(createApprovalRequest).not.toHaveBeenCalled();
+    expect(findPendingApprovalRequest).not.toHaveBeenCalled();
+  });
 });
 
 describe("wrapToolsWithActionGate", () => {
@@ -727,6 +767,39 @@ describe("wrapToolsWithActionGate", () => {
     expect(createApprovalRequest).not.toHaveBeenCalled();
     expect(pauseForApproval).not.toHaveBeenCalled();
   });
+
+  it.each<[
+    "locked-down" | "approval-required",
+    typeof lockedDownRules | typeof approvalRules
+  ]>([
+    ["locked-down", lockedDownRules],
+    ["approval-required", approvalRules],
+  ])("bypasses wrapping for fn_send_message under %s policy", async (presetId, rules) => {
+    const args = { message: "ping" };
+    const result = { ok: true, messageId: "msg-2" };
+    const execute = vi.fn().mockResolvedValue(result);
+    const tool = { name: "fn_send_message", label: "Send Message", description: "", parameters: {}, execute };
+    const createApprovalRequest = vi.fn();
+    const pauseForApproval = vi.fn();
+    const { wrapToolsWithActionGate } = await import("../pi.js");
+    const wrapped = wrapToolsWithActionGate([tool as any], {
+      agentId: "agent-1",
+      agentName: "Agent",
+      isEphemeral: false,
+      taskId: "FN-1",
+      permissionPolicy: { presetId, rules },
+      createApprovalRequest,
+      findApprovalByDedupeKey: vi.fn(),
+      pauseForApproval,
+    });
+
+    expect(wrapped[0]).toBe(tool);
+    await expect((wrapped[0] as any).execute("t1", args)).resolves.toEqual(result);
+    expect(execute).toHaveBeenCalledTimes(1);
+    expect(execute).toHaveBeenCalledWith("t1", args);
+    expect(createApprovalRequest).not.toHaveBeenCalled();
+    expect(pauseForApproval).not.toHaveBeenCalled();
+  });
 });
 
 describe("createFnAgent", () => {

packages/engine/src/pi.ts

@@ -1049,7 +1049,10 @@ function buildPermanentAgentApprovalDedupeKey(input: {
   ].join("|");
 }
 
-const HEARTBEAT_TERMINAL_TOOL_NAME = "fn_heartbeat_done";
+const GATE_BYPASS_TOOL_NAMES = new Set([
+  "fn_heartbeat_done",
+  "fn_send_message",
+]);
 
 export function wrapToolsWithBoundary(
   tools: ToolDefinition[],
@@ -1116,9 +1119,9 @@ export function wrapToolsWithPermanentAgentGating(
   }
 
   return tools.map((tool) => {
-    // FN-3852: heartbeat terminal completion must never be approval-gated,
+    // FN-3852/FN-3855: terminal completion and send-message coordination
-    // otherwise permanent-agent runs can deadlock in an open session.
+    // primitives must never be approval-gated, or open sessions can deadlock.
-    if (tool.name === HEARTBEAT_TERMINAL_TOOL_NAME) {
+    if (GATE_BYPASS_TOOL_NAMES.has(tool.name)) {
       return tool;
     }
 
@@ -1186,9 +1189,9 @@ export function wrapToolsWithActionGate(
   }
 
   return tools.map((tool) => {
-    // FN-3852: heartbeat terminal completion must never be approval-gated,
+    // FN-3852/FN-3855: terminal completion and send-message coordination
-    // otherwise permanent-agent runs can deadlock in an open session.
+    // primitives must never be approval-gated, or open sessions can deadlock.
-    if (tool.name === HEARTBEAT_TERMINAL_TOOL_NAME) {
+    if (GATE_BYPASS_TOOL_NAMES.has(tool.name)) {
       return tool;
     }