slack bridge: attribute inbound human messages with the sender's name

cli/src/slack-bridge.test.ts

@@ -1,7 +1,7 @@
 import { test, describe } from "node:test";
 import { strict as assert } from "node:assert";
 import { parse as parseYaml } from "yaml";
-import { routeSlackMessage, slackToPlain } from "./slack/inbound.js";
+import { routeSlackMessage, slackToPlain, prefixAuthor } from "./slack/inbound.js";
 import { slackAppManifest } from "./slack/manifest.js";
 import { formatReceivedMessage, RECEIVED_MESSAGE_HEADER } from "./slack/announce.js";
 
@@ -11,19 +11,24 @@ const reasonOf = (d: ReturnType<typeof routeSlackMessage>) => (d.action === "ign
 describe("routeSlackMessage", () => {
   test("delivers a human message in a mapped channel to the right agent", () => {
     const d = routeSlackMessage({ type: "message", channel: "C123", user: "U1", text: "focus on the lodash PR" }, MAPPING, "UBOT");
-    assert.deepEqual(d, { action: "deliver", slug: "dependabot-scout", text: "focus on the lodash PR", files: [] });
+    assert.deepEqual(d, { action: "deliver", slug: "dependabot-scout", text: "focus on the lodash PR", files: [], user: "U1" });
   });
 
   test("delivers a file_share with attachments even when the text is empty", () => {
     const files = [{ id: "F1", name: "screenshot.png", mimetype: "image/png", url_private: "https://files.slack.com/F1" }];
     const d = routeSlackMessage({ type: "message", subtype: "file_share", channel: "C123", user: "U1", text: "", files }, MAPPING);
-    assert.deepEqual(d, { action: "deliver", slug: "dependabot-scout", text: "", files });
+    assert.deepEqual(d, { action: "deliver", slug: "dependabot-scout", text: "", files, user: "U1" });
   });
 
   test("delivers a file_share with text and attachments together", () => {
     const files = [{ id: "F2", name: "ticket.pdf", mimetype: "application/pdf", url_private: "https://files.slack.com/F2" }];
     const d = routeSlackMessage({ type: "message", subtype: "file_share", channel: "C123", user: "U1", text: "read this", files }, MAPPING);
-    assert.deepEqual(d, { action: "deliver", slug: "dependabot-scout", text: "read this", files });
+    assert.deepEqual(d, { action: "deliver", slug: "dependabot-scout", text: "read this", files, user: "U1" });
+  });
+
+  test("carries the Slack sender id so the bridge can attribute the message", () => {
+    const d = routeSlackMessage({ type: "message", channel: "C123", user: "UDREW", text: "who am I" }, MAPPING);
+    assert.equal(d.action === "deliver" ? d.user : undefined, "UDREW");
   });
 
   test("ignores the bot's own messages (no loops)", () => {
@@ -46,6 +51,17 @@ describe("routeSlackMessage", () => {
   });
 });
 
+describe("prefixAuthor", () => {
+  test("labels a message with its resolved Slack author", () => {
+    assert.equal(prefixAuthor("focus on the lodash PR", "Drew"), "From Drew (Slack):\nfocus on the lodash PR");
+  });
+
+  test("returns the text unchanged when no name resolved", () => {
+    assert.equal(prefixAuthor("hello", undefined), "hello");
+    assert.equal(prefixAuthor("hello", "   "), "hello");
+  });
+});
+
 describe("formatReceivedMessage", () => {
   test("marks the injected prompt as a received message and italicizes the body", () => {
     const out = formatReceivedMessage("Good morning, review the open Dependabot PRs.");

cli/src/slack/bridge.ts

@@ -2,7 +2,7 @@ import { existsSync, statSync, openSync, readSync, closeSync } from "node:fs";
 import { join } from "node:path";
 import { SocketModeClient } from "@slack/socket-mode";
 import { SlackClient } from "./client.js";
-import { routeSlackMessage, ChannelMapping } from "./inbound.js";
+import { routeSlackMessage, prefixAuthor, ChannelMapping } from "./inbound.js";
 import { formatTranscriptLines, formatCodexRolloutLines, TERMINAL_STOP_REASONS } from "./format.js";
 import { loadAgentsConfig } from "../agents/config.js";
 import { agentIdentity } from "../agents/identity.js";
@@ -197,6 +197,17 @@ export async function runSlackBridge(opts: BridgeOptions): Promise<void> {
   // track recent relays here and drop the matching echo. Keyed by slug.
   const recentRelays = new Map<string, { text: string; ts: number }[]>();
   const RELAY_ECHO_TTL_MS = 90_000;
+  // Resolve a Slack user id to a display name once and reuse it, so the agent
+  // sees who is steering it on every inbound message without an API call per
+  // message. A failed lookup is not cached, so a transient error can recover.
+  const userNameCache = new Map<string, string>();
+  const resolveUserNameCached = async (userId: string): Promise<string | undefined> => {
+    const hit = userNameCache.get(userId);
+    if (hit) return hit;
+    const name = await client.resolveUserName(userId);
+    if (name) userNameCache.set(userId, name);
+    return name;
+  };
   const consumeRelayEcho = (slug: string, mirrored: string): boolean => {
     const list = recentRelays.get(slug);
     if (!list?.length) return false;
@@ -647,15 +658,21 @@ export async function runSlackBridge(opts: BridgeOptions): Promise<void> {
     const prompt = formatPromptWithAttachments(decision.text, downloaded);
     if (!prompt) return; // text empty AND every attachment failed -> nothing to relay
 
+    // Prefix the sender so the agent can see who is steering it. Only human
+    // messages reach here (bot posts are dropped upstream), so this never
+    // double-labels an agent's own "From <Agent>:" line.
+    const authorName = decision.user ? await resolveUserNameCached(decision.user) : undefined;
+    const authored = prefixAuthor(prompt, authorName);
+
     // Mark this relay so the daemon does not echo it back to the channel
     // (it already appears there as that person's Slack message). Recorded
     // before the paste so the marker is in place before UserPromptSubmit.
     recordAnnounceSuppress(agentIdentity(decision.slug).sessionId);
     // Also remember it for the in-process Codex rollout-echo guard above.
     const relays = recentRelays.get(decision.slug) ?? [];
-    relays.push({ text: prompt, ts: Date.now() });
+    relays.push({ text: authored, ts: Date.now() });
     recentRelays.set(decision.slug, relays);
-    pasteTmuxPrompt(decision.slug, prompt); // tmux session name == slug
+    pasteTmuxPrompt(decision.slug, authored); // tmux session name == slug
 
     // Post a 👀 ack and light the working pill on it, ONLY if the agent
     // isn't already mid-turn. The eyes give the channel a visible

cli/src/slack/client.ts

@@ -65,6 +65,20 @@ export class SlackClient {
     });
   }
 
+  /// Resolve a Slack user id to a human-readable name (display name preferred,
+  /// then real name, then the handle). Returns undefined if the lookup fails so
+  /// callers can fall back gracefully.
+  async resolveUserName(userId: string): Promise<string | undefined> {
+    try {
+      const r = await this.web.users.info({ user: userId });
+      const u = r.user as any;
+      const p = u?.profile ?? {};
+      return p.display_name || p.real_name || u?.real_name || u?.name || undefined;
+    } catch {
+      return undefined;
+    }
+  }
+
   /// Resolve "#name" / "name" to a channel id. Ids (C…/G…) are returned as-is.
   async resolveChannelId(nameOrId: string): Promise<string | undefined> {
     if (/^[CG][A-Z0-9]+$/.test(nameOrId)) return nameOrId;

cli/src/slack/inbound.ts

@@ -27,7 +27,18 @@ export interface SlackMessageEvent {
 
 export type InboundDecision =
   | { action: "ignore"; reason: string }
-  | { action: "deliver"; slug: string; text: string; files: SlackFile[] };
+  | { action: "deliver"; slug: string; text: string; files: SlackFile[]; user?: string };
+
+/// Prefix an inbound message with its Slack author so the agent can see who is
+/// steering it. Agent-to-agent posts go through the bot token and are dropped
+/// as bot messages before they reach here, so this only labels human messages
+/// and never double-prefixes an agent's own "From <Agent>:" line. With no
+/// resolved name the text is returned unchanged.
+export function prefixAuthor(text: string, authorName?: string): string {
+  const name = authorName?.trim();
+  if (!name) return text;
+  return `From ${name} (Slack):\n${text}`;
+}
 
 /// Convert Slack mrkdwn to plain text for the agent: unwrap links/mentions and
 /// unescape HTML entities Slack adds.
@@ -66,5 +77,5 @@ export function routeSlackMessage(
   const files = event.files ?? [];
   if (!text && files.length === 0) return { action: "ignore", reason: "empty" };
 
-  return { action: "deliver", slug, text, files };
+  return { action: "deliver", slug, text, files, user: event.user };
 }