diff --git a/bun.lock b/bun.lock
index 877eeb8c..856999ac 100644
--- a/bun.lock
+++ b/bun.lock
@@ -444,6 +444,7 @@
         "@corbits/agent-runtime": "workspace:*",
         "@corbits/approvals": "workspace:*",
         "@corbits/commands": "workspace:*",
+        "@corbits/error-sink": "workspace:*",
         "@corbits/folded-runs": "workspace:*",
         "@corbits/memory": "github:corbitsdev/corbits-memory#9e6f213fa2c002b531d3f6af1aa0abd737b8afe3",
         "@corbits/turn-artifacts": "workspace:*",
@@ -3483,8 +3484,6 @@
 
     "@typescript-eslint/eslint-plugin/ignore": ["ignore@7.0.6", "", {}, "sha512-BAg6QkE8W+TuQLrrw0Ugr7HegXduRuuj8/ti2kSOc+jz1dmx8/WNcjr6XGnq5YpDWxFwwaavqD0+jIUOKelTsw=="],
 
-    "@workbench/hub/@corbits/mailbox": ["@corbits/mailbox@github:corbitsdev/corbits-mailbox#caa5214", { "dependencies": { "@hono/standard-validator": "0.2.3", "@standard-community/standard-json": "0.3.5", "@standard-community/standard-openapi": "0.2.9", "arktype": "2.1.29", "hono-openapi": "1.3.1" }, "peerDependencies": { "@intx/log": "^0.2.2", "@intx/mime": "^0.2.2", "@intx/types": "^0.2.2", "drizzle-orm": "^0.45.2", "hono": "^4.12.0", "postgres": "^3.4.0" } }, "corbitsdev-corbits-mailbox-caa5214", "sha512-z8DRBFgA4ukM8p29COeaMjfKZYe5jAUF4OBMiaIQFuW592+DGD/y6Ws6SjGlXmR9azkHNWh8oTzjlWlRP24vsQ=="],
-
     "@workbench/hub/@corbits/memory": ["@corbits/memory@github:corbitsdev/corbits-memory#9e6f213", { "dependencies": { "@intx/agent": "0.2.2", "@intx/authz": "0.2.2", "@intx/hub-api": "0.2.2", "@intx/log": "0.2.2", "@intx/workflow": "0.2.2", "arktype": "^2.1.29", "drizzle-orm": "^0.45.1", "hono": "^4.9.0", "hono-openapi": "^1.3.1", "postgres": "^3.4.7" } }, "corbitsdev-corbits-memory-9e6f213", "sha512-utnM4ZT2zmslcPXYWAAqxlDNLcpGsXFiTOtj8h7+OXnhCP0Eaw8yl25+yCTyHpvt3jcdeG4h5uFsSj7ou0BZCA=="],
 
     "ajv-formats/ajv": ["ajv@8.20.0", "", { "dependencies": { "fast-deep-equal": "^3.1.3", "fast-uri": "^3.0.1", "json-schema-traverse": "^1.0.0", "require-from-string": "^2.0.2" } }, "sha512-Thbli+OlOj+iMPYFBVBfJ3OmCAnaSyNn4M1vz9T6Gka5Jt9ba/HIR56joy65tY6kx/FCF5VXNB819Y7/GUrBGA=="],
diff --git a/packages/chat/package.json b/packages/chat/package.json
index cc34917e..b600582f 100644
--- a/packages/chat/package.json
+++ b/packages/chat/package.json
@@ -29,6 +29,7 @@
     "@corbits/agent-runtime": "workspace:*",
     "@corbits/approvals": "workspace:*",
     "@corbits/commands": "workspace:*",
+    "@corbits/error-sink": "workspace:*",
     "@corbits/folded-runs": "workspace:*",
     "@corbits/memory": "github:corbitsdev/corbits-memory#9e6f213fa2c002b531d3f6af1aa0abd737b8afe3",
     "@corbits/turn-artifacts": "workspace:*",
diff --git a/packages/chat/src/workbench-service.ts b/packages/chat/src/workbench-service.ts
index 8d8e6dc9..a26a4205 100644
--- a/packages/chat/src/workbench-service.ts
+++ b/packages/chat/src/workbench-service.ts
@@ -8,6 +8,7 @@
 // full `ChatPlatform`/`ChatStore`.
 import { generateId } from "@intx/hub-common";
 import { getLogger } from "@intx/log";
+import { reportError } from "@corbits/error-sink";
 import { InferenceResolutionError } from "@corbits/folded-runs";
 import { workbenchTemplate } from "@corbits/workflow-catalog";
 import { encodeParts } from "./codec";
@@ -1216,14 +1217,22 @@ async function dispatchTurnBatch(
           requestMessageIds: messageIds,
         });
       } catch (err) {
+        const refId = reportError(err, {
+          operation: "chat.dispatchTurn",
+          tenantId,
+          roomId: workbenchId,
+          agentId: agentAddress,
+          extra: { messageIds },
+        });
         fanoutLog.error(
           "Asking {agentAddress} for a turn failed for workbench " +
-            "{workbenchId}'s message(s) {messageIds}; posting an " +
-            "undelivered notice in its voice: {err}",
+            "{workbenchId}'s message(s) {messageIds} (ref {refId}); " +
+            "posting an undelivered notice in its voice: {err}",
           {
             agentAddress,
             workbenchId,
             messageIds,
+            refId,
             err,
           },
         );
@@ -1232,6 +1241,7 @@ async function dispatchTurnBatch(
           workbenchId,
           agentAddress,
           cause: err,
+          refId,
         });
       }
     }),
@@ -1351,9 +1361,16 @@ async function postUndeliveredNotice(
     readonly workbenchId: string;
     readonly agentAddress: string;
     readonly cause: unknown;
+    /** The `reportError` refId for the cause the caller already logged —
+     * a person can quote this to support instead of the notice reading
+     * as unexplainable silence. */
+    readonly refId: string;
   },
 ): Promise<void> {
   try {
+    const notice = isCredentialDispatchFailure(input.cause)
+      ? CREDENTIAL_UNDELIVERED_NOTICE
+      : RETRYABLE_UNDELIVERED_NOTICE;
     await postRoomMessage(deps, {
       tenantId: input.tenantId,
       workbenchId: input.workbenchId,
@@ -1362,9 +1379,7 @@ async function postUndeliveredNotice(
       parts: [
         {
           kind: "text",
-          text: isCredentialDispatchFailure(input.cause)
-            ? CREDENTIAL_UNDELIVERED_NOTICE
-            : RETRYABLE_UNDELIVERED_NOTICE,
+          text: `${notice} (ref ${input.refId})`,
           turnFailed: true,
         },
       ],
diff --git a/packages/chat/test/workbench-service.test.ts b/packages/chat/test/workbench-service.test.ts
index c80fdeb9..a2069aef 100644
--- a/packages/chat/test/workbench-service.test.ts
+++ b/packages/chat/test/workbench-service.test.ts
@@ -370,6 +370,15 @@ describe("message fan-out", () => {
       expect(text).toContain("send it again");
       expect(text).not.toContain("model key");
     });
+
+    // CL-6644: a dispatch failure that never surfaces a logged cause is
+    // unfixable by anyone who cannot read the code — the notice must
+    // carry a `reportError` refId a person can quote to support, and
+    // that refId must be the one the caller actually logged.
+    test("carries a reportError refId a person can quote to support", async () => {
+      const text = await noticeTextFor(new Error("sidecar unavailable"));
+      expect(text).toMatch(/\(ref [^)]+\)$/);
+    });
   });
 
   test("a message to a chat delivers to its agent without a mention", async () => {