fix(eve): bound Slack approval callback payloads

.changeset/bound-slack-approval-callbacks.md

@@ -0,0 +1,5 @@
+---
+"eve": patch
+---
+
+Keep Slack tool approval callbacks responsive for large inputs by omitting duplicated input details from fallback text. The approval card still shows the truncated input preview.

packages/eve/src/public/channels/slack/defaults.test.ts

@@ -1,7 +1,8 @@
 import { describe, expect, it, vi } from "vitest";
 
 import type { SessionContext } from "#public/definitions/callback-context.js";
-import { defaultEvents } from "#public/channels/slack/defaults.js";
+import { defaultEvents, defaultInputRequestedHandler } from "#public/channels/slack/defaults.js";
+import { HITL_ACTION_PREFIX } from "#public/channels/slack/hitl.js";
 import type { SlackChannelState, SlackEventContext } from "#public/channels/slack/slackChannel.js";
 
 function sessionContext(
@@ -51,6 +52,72 @@ function authRequiredEvent(
   };
 }
 
+describe("defaultInputRequestedHandler", () => {
+  it("bounds callback payloads independently of the full approval input", async () => {
+    const { channel, post } = buildChannelStub();
+    const handler = defaultInputRequestedHandler();
+
+    for (const inputLength of [5_000, 50_000]) {
+      await handler(
+        {
+          requests: [
+            {
+              action: {
+                callId: "call_cloud_agent",
+                input: {
+                  prompt: `cloud-agent-prompt ${"x".repeat(inputLength)} tail-sentinel`,
+                },
+                kind: "tool-call",
+                toolName: "spawn-cloud-agent",
+              },
+              display: "confirmation",
+              kind: "tool-approval",
+              options: [
+                { id: "approve", label: "Approve" },
+                { id: "cancel", label: "Cancel" },
+              ],
+              prompt: "Approve tool call: spawn-cloud-agent",
+              requestId: "approval_cloud_agent",
+            },
+          ],
+          sequence: 0,
+          stepIndex: 0,
+          turnId: "t1",
+        },
+        channel,
+        sessionCtx,
+      );
+    }
+
+    const callbackSizes = post.mock.calls.map(([message]) => {
+      const renderedMessage = JSON.stringify(message);
+      expect(renderedMessage.split("cloud-agent-prompt").length - 1).toBe(1);
+      expect(renderedMessage).not.toContain("tail-sentinel");
+
+      const callbackBody = new URLSearchParams({
+        payload: JSON.stringify({
+          actions: [
+            {
+              action_id: `${HITL_ACTION_PREFIX}approval_cloud_agent:button:1`,
+              value: "approve",
+            },
+          ],
+          channel: { id: "C123" },
+          message,
+          team: { id: "T01" },
+          type: "block_actions",
+          user: { id: "U01" },
+        }),
+      }).toString();
+      return new TextEncoder().encode(callbackBody).byteLength;
+    });
+
+    expect(callbackSizes).toHaveLength(2);
+    expect(callbackSizes[1]).toBe(callbackSizes[0]);
+    expect(callbackSizes[0]).toBeLessThanOrEqual(6_000);
+  });
+});
+
 describe("defaultEvents authorization.required", () => {
   it("posts a public status and delivers the challenge ephemerally to the triggering user", async () => {
     const { channel, post, postEphemeral } = buildChannelStub({ triggeringUserId: "U777" });

packages/eve/src/public/channels/slack/hitl.test.ts

@@ -363,7 +363,7 @@ describe("renderInputRequestBlocks", () => {
 });
 
 describe("formatInputRequestFallbackText", () => {
-  it("includes approval tool input in Slack fallback text", () => {
+  it("keeps approval tool input out of Slack fallback text", () => {
     const text = formatInputRequestFallbackText(
       makeRequest({
         action: {
@@ -386,9 +386,7 @@ describe("formatInputRequestFallbackText", () => {
       }),
     );
 
-    expect(text).toContain("Approve tool call: mongodb-mutate");
-    expect(text).toContain('"collection": "orgs"');
-    expect(text).toContain('"_id": "48gtnni64rxqtaoh"');
+    expect(text).toBe("Approve tool call: mongodb-mutate");
   });
 
   it("leaves non-approval fallback text unchanged", () => {

packages/eve/src/public/channels/slack/hitl.ts

@@ -197,12 +197,11 @@ export function renderInputRequestBlocks(request: InputRequest): unknown[] {
 
 /**
  * Creates the fallback text for one HITL request. Slack clients use this
- * outside the rich Block Kit surface, so include the same approval details
- * that appear in the blocks.
+ * outside the rich Block Kit surface. Keep it concise because Slack includes
+ * this text alongside the full block list in interaction callbacks.
  */
 export function formatInputRequestFallbackText(request: InputRequest): string {
-  const details = formatToolInputDetails(request);
-  return details === undefined ? request.prompt : `${request.prompt}\n${details}`;
+  return request.prompt;
 }
 
 /**

packages/eve/src/public/channels/slack/slackChannel.test.ts

@@ -516,7 +516,7 @@ describe("slackChannel() default event handlers", () => {
     };
     expect(body).toMatchObject({
       channel: "C01",
-      text: 'Approve tool call: mongodb-mutate\n*Tool input*\n```\n{\n  "operation": "deleteMany"\n}\n```',
+      text: "Approve tool call: mongodb-mutate",
       thread_ts: "1700000000.000001",
     });