diff --git a/apps/hub/src/index.ts b/apps/hub/src/index.ts
index 1c27b2cd..e2ffe56a 100644
--- a/apps/hub/src/index.ts
+++ b/apps/hub/src/index.ts
@@ -169,6 +169,7 @@ import {
 import {
   deliveryWorkbenchRequiredForWorkflowName,
   isAutomatableWorkflowName,
+  isConversationalWorkflowName,
   validateTriggerFieldsAtCreate,
   workflowCatalogEntry,
   workflowDisplayName,
@@ -1483,11 +1484,16 @@ export async function createHub(config: HubConfig) {
 
   // The one "is this a conversational agent?" ruling, shared by every
   // picker that offers agents to a person and by a routine's `"agent"`-kind
-  // trigger-field validation below: automatable catalog workflows
-  // (routines material) and workbench-host anchor definitions (chat's own
-  // plumbing, never a person-facing agent) belong in neither.
+  // trigger-field validation below: a catalog workflow whose entry says
+  // `conversational: false` (routine/automation material — Echo, "Last 30
+  // days research report", …) and workbench-host anchor definitions
+  // (chat's own plumbing, never a person-facing agent) belong in neither.
+  // `isConversationalWorkflowName`, not `isAutomatableWorkflowName`: a
+  // non-automatable utility workflow (Echo, the research report a routine
+  // delivers) is still not conversational, and the old automatable-only
+  // check let both leak into every agent picker (CL-6649).
   const isConversationalAgentDefinition = (definition: { name: string }) =>
-    !isAutomatableWorkflowName(definition.name) &&
+    isConversationalWorkflowName(definition.name) &&
     !isWorkbenchHostDefinitionName(definition.name);
 
   // A second, narrower ruling layered on top of the ruling above, for
diff --git a/packages/chat-ui/src/invite-agent-dialog.tsx b/packages/chat-ui/src/invite-agent-dialog.tsx
index cc55eacb..dd91c88f 100644
--- a/packages/chat-ui/src/invite-agent-dialog.tsx
+++ b/packages/chat-ui/src/invite-agent-dialog.tsx
@@ -21,6 +21,7 @@ import {
 import { Users, WarningCircle } from "@corbits/icons";
 import { useEffect, useState } from "react";
 
+import { humanizeSlug } from "@corbits/chat/display-name";
 import {
   ChatApiError,
   describeChatError,
@@ -151,31 +152,53 @@ export function InviteAgentDialog({
             />
           ) : (
             <ul className="chat-invitable-list">
-              {state.items.map((definition) => (
-                <li
-                  key={definition.id}
-                  className="chat-invitable-item"
-                  data-testid="invitable-definition"
-                >
-                  <span>{definition.description ?? definition.name}</span>
-                  <Button
-                    variant="outline"
-                    size="sm"
-                    disabled={invitingId !== null}
-                    onClick={() => void handleInvite(definition.id)}
+              {state.items.map((definition) => {
+                // `description` carries the definition's real display
+                // name (set at creation), never a summary sentence — see
+                // `InvitableDefinition`'s own doc comment — so the
+                // fallback below is "no display name was ever set", not
+                // "no description exists". `name` is the immutable slug
+                // and never belongs in the title slot on its own.
+                const displayName =
+                  definition.description ?? humanizeSlug(definition.name);
+                return (
+                  <li
+                    key={definition.id}
+                    className="chat-invitable-item"
+                    data-testid="invitable-definition"
                   >
-                    {invitingId === definition.id
-                      ? CHAT_STRINGS.inviteAgentInviting
-                      : CHAT_STRINGS.inviteAgentAction}
-                  </Button>
-                </li>
-              ))}
+                    <span className="chat-invitable-item-name">
+                      {displayName}
+                    </span>
+                    <Button
+                      variant="outline"
+                      size="sm"
+                      disabled={invitingId !== null}
+                      onClick={() => void handleInvite(definition.id)}
+                    >
+                      {invitingId === definition.id
+                        ? CHAT_STRINGS.inviteAgentInviting
+                        : CHAT_STRINGS.inviteAgentAction}
+                    </Button>
+                  </li>
+                );
+              })}
               {jimmyMissing && (
                 <li
                   className="chat-invitable-item"
                   data-testid="quick-create-jimmy"
                 >
-                  <span>{JIMMY_QUICK_CREATE.description}</span>
+                  <span className="chat-invitable-item-info">
+                    <span className="chat-invitable-item-name">
+                      {JIMMY_QUICK_CREATE.name}
+                      <span className="chat-invitable-item-attribution">
+                        {CHAT_STRINGS.inviteAgentFirstPartyAttribution}
+                      </span>
+                    </span>
+                    <span className="chat-invitable-item-description">
+                      {JIMMY_QUICK_CREATE.description}
+                    </span>
+                  </span>
                   <Button
                     variant="outline"
                     size="sm"
diff --git a/packages/chat-ui/src/strings.ts b/packages/chat-ui/src/strings.ts
index 9fd8e26e..a157773c 100644
--- a/packages/chat-ui/src/strings.ts
+++ b/packages/chat-ui/src/strings.ts
@@ -108,6 +108,7 @@ export const CHAT_STRINGS = {
   inviteAgentQuickCreateAction: "Add",
   inviteAgentQuickCreating: "Adding…",
   inviteAgentQuickCreateError: "Couldn't add Jimmy — try again.",
+  inviteAgentFirstPartyAttribution: "by Corbits",
   forkThreadAction: "Fork",
   forkThreadError: "Couldn't fork that message into a thread — try again.",
   replyInThreadAction: "Reply in thread",
diff --git a/packages/chat-ui/src/styles.css b/packages/chat-ui/src/styles.css
index b3e2cf62..1e381ac7 100644
--- a/packages/chat-ui/src/styles.css
+++ b/packages/chat-ui/src/styles.css
@@ -3322,6 +3322,31 @@
   font-size: 0.875rem;
 }
 
+.chat-invitable-item-info {
+  display: flex;
+  flex-direction: column;
+  gap: 0.125rem;
+  min-width: 0;
+}
+
+.chat-invitable-item-name {
+  font-weight: 600;
+}
+
+.chat-invitable-item-attribution {
+  margin-left: 0.375rem;
+  font-weight: 400;
+  color: var(--muted-foreground);
+}
+
+.chat-invitable-item-description {
+  color: var(--muted-foreground);
+  font-size: 0.8125rem;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
 /* Guided-dialog stepper chrome: uppercase step label over a thin segmented
    rail, filled in the host's accent as the flow advances, with one calm
    guidance sentence underneath. Mirrors the onboarding wizard rail's visual
diff --git a/packages/chat-ui/test/invite-agent-dialog.test.tsx b/packages/chat-ui/test/invite-agent-dialog.test.tsx
index dc3b4cb3..745adb3e 100644
--- a/packages/chat-ui/test/invite-agent-dialog.test.tsx
+++ b/packages/chat-ui/test/invite-agent-dialog.test.tsx
@@ -91,6 +91,24 @@ describe("InviteAgentDialog's Jimmy quick-create row", () => {
     expect(row?.textContent).toContain(JIMMY_QUICK_CREATE.description);
   });
 
+  // CL-6649: the row used to render only `JIMMY_QUICK_CREATE.description`
+  // ("Searches Giphy and replies with a GIF") — Jimmy's own name never
+  // appeared at all. The name must lead, with the description as a
+  // secondary line and a first-party attribution alongside the name.
+  test("renders Jimmy's name prominently, attributed to Corbits, with the description as a secondary line", async () => {
+    const el = await mount({
+      invitable: () => [{ id: "wfd_echo", name: "echo" }],
+      onInvite: async () => undefined,
+      onOpenChange: () => undefined,
+    });
+    const row = el.querySelector('[data-testid="quick-create-jimmy"]');
+    const name = row?.querySelector(".chat-invitable-item-name");
+    const description = row?.querySelector(".chat-invitable-item-description");
+    expect(name?.textContent).toContain(JIMMY_QUICK_CREATE.name);
+    expect(name?.textContent).toContain("by Corbits");
+    expect(description?.textContent).toBe(JIMMY_QUICK_CREATE.description);
+  });
+
   test("is absent once the tenant's invitable list already includes Jimmy", async () => {
     const el = await mount({
       invitable: () => [{ id: "wfd_jimmy", name: JIMMY_QUICK_CREATE.handle }],
diff --git a/packages/chat/src/routes.ts b/packages/chat/src/routes.ts
index 99527db0..ebecaa35 100644
--- a/packages/chat/src/routes.ts
+++ b/packages/chat/src/routes.ts
@@ -2685,11 +2685,38 @@ export function createChatRoutes(deps: CreateChatRoutesDeps): Hono<TenantEnv> {
     async (c) => {
       const tenant = c.get("tenant");
       const workbenchId = c.req.param("id");
-      if (!(await workbenchInTenant(deps.store, tenant.id, workbenchId))) {
+      const existing = await deps.store.getWorkbenchSettings(
+        tenant.id,
+        workbenchId,
+      );
+      if (
+        existing === undefined &&
+        !(await workbenchInTenant(deps.store, tenant.id, workbenchId))
+      ) {
         return c.json(ErrorEnvelope("not_found", "workbench not found"), 404);
       }
+
+      // A definition already in the room isn't invitable — resolve each
+      // current agent participant's address back to its definitionId so
+      // the listing never re-offers someone already present (CL-6649).
+      const presentDefinitionIds = new Set(
+        (
+          await Promise.all(
+            (existing !== undefined ? participantsOf(existing.settings) : [])
+              .filter((participant) => isAgentAddress(participant.address))
+              .map((participant) =>
+                deps.platform.resolveDefinitionIdByAddress(participant.address),
+              ),
+          )
+        ).filter((id): id is string => id !== undefined),
+      );
+
       const items = await deps.platform.listInvitableDefinitions(tenant.id);
-      return c.json({ items: items.filter(deps.isInvitableDefinition) });
+      return c.json({
+        items: items
+          .filter(deps.isInvitableDefinition)
+          .filter((item) => !presentDefinitionIds.has(item.id)),
+      });
     },
   );
 
diff --git a/packages/chat/test/routes.test.ts b/packages/chat/test/routes.test.ts
index 203786af..61a48103 100644
--- a/packages/chat/test/routes.test.ts
+++ b/packages/chat/test/routes.test.ts
@@ -2363,6 +2363,41 @@ describe("GET /workbenches/:id/invitable", () => {
     expect(body.items).toEqual([{ id: "wfd_echo", name: "echo" }]);
   });
 
+  // CL-6649: a definition already invited into the room isn't invitable
+  // again — the dialog must never re-offer someone already present.
+  test("excludes a definition whose agent is already a participant", async () => {
+    const deps = buildDeps({
+      platform: fakePlatform({
+        invitable: [
+          { id: "wfd_echo", name: "echo" },
+          { id: "wfd_myra", name: "assistant", description: "Myra" },
+        ],
+        resolveDefinitionIdByAddress: async (address) =>
+          address === "ins_invited1@acme.example" ? "wfd_echo" : undefined,
+      }),
+    });
+    const app = mountAs(createChatRoutes(deps), "prn_alice");
+    const { body: workbench } = await createWorkbench(app, {
+      kind: "workbench",
+    });
+    await app.request(`/workbenches/${workbench.id}/invite`, {
+      method: "POST",
+      headers: { "content-type": "application/json" },
+      body: JSON.stringify({ definitionId: "wfd_echo" }),
+    });
+
+    const response = await app.request(
+      `/workbenches/${workbench.id}/invitable`,
+    );
+    expect(response.status).toBe(200);
+    const body = (await response.json()) as {
+      items: { id: string; name: string; description?: string }[];
+    };
+    expect(body.items).toEqual([
+      { id: "wfd_myra", name: "assistant", description: "Myra" },
+    ]);
+  });
+
   test("a denied grant is rejected", async () => {
     const deps = buildDeps({
       requireGrant: () => async (c) =>
diff --git a/packages/workflow-catalog/test/catalog.test.ts b/packages/workflow-catalog/test/catalog.test.ts
index 7eaa1735..2b5a7ff2 100644
--- a/packages/workflow-catalog/test/catalog.test.ts
+++ b/packages/workflow-catalog/test/catalog.test.ts
@@ -116,6 +116,18 @@ describe("workflow catalog", () => {
       expect(isConversationalWorkflowName("wfd_deadbeef")).toBe(true);
     });
 
+    // CL-6649: `echo` and `last-30-days-research` are both non-automatable
+    // AND non-conversational — the exact combination that let a picker
+    // gated on `!isAutomatableWorkflowName` alone (rather than
+    // `isConversationalWorkflowName`) mistake a routine's delivery
+    // workflow, and the Echo wiring check, for an invitable chat agent.
+    test("a non-automatable utility is still non-conversational (the CL-6649 trap)", () => {
+      for (const name of ["echo", "last-30-days-research"]) {
+        expect(isAutomatableWorkflowName(name)).toBe(false);
+        expect(isConversationalWorkflowName(name)).toBe(false);
+      }
+    });
+
     test("every catalog entry declares a conversational flag", () => {
       for (const entry of WORKFLOW_CATALOG) {
         expect(typeof entry.conversational).toBe("boolean");
diff --git a/scripts/e2e/chat.test.ts b/scripts/e2e/chat.test.ts
index 94010743..d7802a9b 100644
--- a/scripts/e2e/chat.test.ts
+++ b/scripts/e2e/chat.test.ts
@@ -685,29 +685,17 @@ describe.skipIf(databaseUrl === undefined)("chat e2e", () => {
   }, 90_000);
 
   test("inviting the echo agent launches its own run, joins the workbench, and receives @mentions", async () => {
-    const invitableRes = await api(
-      "GET",
-      `/api/tenants/${tenantId}/chat/workbenches/${workbenchId}/invitable`,
-      undefined,
-      user1.cookies,
-    );
-    expectStatus("list invitable definitions", invitableRes, 200);
-    const invitable = arrayField(
-      invitableRes.data,
-      "items",
-      "list invitable definitions",
-    ) as { id: string; name: string }[];
-    const echoDefinition = invitable.find((item) => item.name === "echo");
-    if (echoDefinition === undefined) {
-      throw new Error(
-        `no invitable definition named "echo": ${JSON.stringify(invitable)}`,
-      );
-    }
+    // Echo is a non-conversational wiring check (`conversational: false`
+    // in the workflow catalog, CL-6649) — the invite dialog's own
+    // listing correctly excludes it, so this test resolves its
+    // definition id directly by name rather than through that filtered
+    // listing.
+    const echoId = await echoDefinitionId();
 
     const invited = await api(
       "POST",
       `/api/tenants/${tenantId}/chat/workbenches/${workbenchId}/invite`,
-      { definitionId: echoDefinition.id },
+      { definitionId: echoId },
       user1.cookies,
     );
     expectStatus("invite echo agent", invited, 201);
@@ -717,7 +705,7 @@ describe.skipIf(databaseUrl === undefined)("chat e2e", () => {
       "invite echo agent",
     );
     expect(stringField(invited.data, "definitionId", "invite echo agent")).toBe(
-      echoDefinition.id,
+      echoId,
     );
     const invitedLocalPart = invitedAddress.split("@")[0];
     if (invitedLocalPart === undefined || invitedLocalPart === "") {
@@ -786,26 +774,19 @@ describe.skipIf(databaseUrl === undefined)("chat e2e", () => {
     expect(fresh.length).toBeGreaterThan(0);
   }, 90_000);
 
+  // Echo is a non-conversational wiring check (`conversational: false` in
+  // the workflow catalog, CL-6649) — it never appears in the invite
+  // dialog's own (correctly filtered) listing, so its definition id is
+  // resolved directly by name instead.
   async function echoDefinitionId(): Promise<string> {
-    const invitableRes = await api(
+    const byNameRes = await api(
       "GET",
-      `/api/tenants/${tenantId}/chat/workbenches/${workbenchId}/invitable`,
+      `/api/tenants/${tenantId}/agent-definitions/by-name/echo`,
       undefined,
       user1.cookies,
     );
-    expectStatus("list invitable definitions", invitableRes, 200);
-    const invitable = arrayField(
-      invitableRes.data,
-      "items",
-      "list invitable definitions",
-    ) as { id: string; name: string }[];
-    const echoDefinition = invitable.find((item) => item.name === "echo");
-    if (echoDefinition === undefined) {
-      throw new Error(
-        `no invitable definition named "echo": ${JSON.stringify(invitable)}`,
-      );
-    }
-    return echoDefinition.id;
+    expectStatus("resolve echo definition by name", byNameRes, 200);
+    return stringField(byNameRes.data, "id", "resolve echo definition by name");
   }
 
   test("a chat auto-invites the echo agent and delivers un-mentioned messages to it", async () => {