fix: hydrate Slack thread root files (#1479) (thanks @travisirby)

CHANGELOG.md

@@ -40,6 +40,7 @@ Docs: https://docs.clawd.bot
 - Agents/TUI: honor user-pinned auth profiles during cooldown and preserve search picker ranking. (#1432) Thanks @tobiasbischoff.
 - Docs: fix gog auth services example to include docs scope. (#1454) Thanks @zerone0x.
 - Slack: read thread replies for message reads when threadId is provided (replies-only). (#1450) Thanks @rodrigouroz.
+- Slack: hydrate thread root attachments for replies and include multi-file context. (#1479) Thanks @travisirby.
 - macOS: prefer linked channels in gateway summary to avoid false “not linked” status.
 - Providers: improve GitHub Copilot integration (enterprise support, base URL, and auth flow alignment).
 

src/slack/monitor/media.ts

@@ -5,17 +5,28 @@ import { fetchRemoteMedia } from "../../media/fetch.js";
 import { saveMediaBuffer } from "../../media/store.js";
 import type { SlackFile } from "../types.js";
 
-export async function resolveSlackMedia(params: {
+export type SlackResolvedMedia = {
-  files?: SlackFile[];
-  token: string;
-  maxBytes: number;
-}): Promise<{
   path: string;
   contentType?: string;
   placeholder: string;
-} | null> {
+};
+
+export function resolveSlackFilePlaceholder(files?: SlackFile[]): string | undefined {
+  if (!files || files.length === 0) return undefined;
+  const named = files.find((file) => file?.name?.trim());
+  if (named?.name) return `[Slack file: ${named.name}]`;
+  return "[Slack file]";
+}
+
+export async function resolveSlackMediaList(params: {
+  files?: SlackFile[];
+  token: string;
+  maxBytes: number;
+}): Promise<SlackResolvedMedia[]> {
   const files = params.files ?? [];
+  const resolved: SlackResolvedMedia[] = [];
   for (const file of files) {
+    if (file.size && file.size > params.maxBytes) continue;
     const url = file.url_private_download ?? file.url_private;
     if (!url) continue;
     try {
@@ -37,22 +48,23 @@ export async function resolveSlackMedia(params: {
         params.maxBytes,
       );
       const label = fetched.fileName ?? file.name;
-      return {
+      resolved.push({
         path: saved.path,
         contentType: saved.contentType,
         placeholder: label ? `[Slack file: ${label}]` : "[Slack file]",
-      };
+      });
     } catch {
       // Ignore download failures and fall through to the next file.
     }
   }
-  return null;
+  return resolved;
 }
 
 export type SlackThreadStarter = {
-  text: string;
+  text?: string;
   userId?: string;
   ts?: string;
+  files?: SlackFile[];
 };
 
 const THREAD_STARTER_CACHE = new Map<string, SlackThreadStarter>();
@@ -71,14 +83,18 @@ export async function resolveSlackThreadStarter(params: {
       ts: params.threadTs,
       limit: 1,
       inclusive: true,
-    })) as { messages?: Array<{ text?: string; user?: string; ts?: string }> };
+    })) as {
+      messages?: Array<{ text?: string; user?: string; ts?: string; files?: SlackFile[] }>;
+    };
     const message = response?.messages?.[0];
     const text = (message?.text ?? "").trim();
-    if (!message || !text) return null;
+    const hasFiles = Boolean(message?.files && message.files.length > 0);
+    if (!message || (!text && !hasFiles)) return null;
     const starter: SlackThreadStarter = {
-      text,
+      text: text || undefined,
       userId: message.user,
       ts: message.ts,
+      files: message.files,
     };
     THREAD_STARTER_CACHE.set(cacheKey, starter);
     return starter;

src/slack/monitor/message-handler/prepare.thread-media.test.ts

@@ -0,0 +1,188 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("../media.js", async () => {
+  const actual = await vi.importActual<typeof import("../media.js")>("../media.js");
+  return {
+    ...actual,
+    resolveSlackMediaList: vi.fn(),
+    resolveSlackThreadStarter: vi.fn(),
+  };
+});
+
+import type { App } from "@slack/bolt";
+
+import type { ClawdbotConfig } from "../../../config/config.js";
+import type { RuntimeEnv } from "../../../runtime.js";
+import type { ResolvedSlackAccount } from "../../accounts.js";
+import type { SlackMessageEvent } from "../../types.js";
+import { createSlackMonitorContext } from "../context.js";
+import { resolveSlackMediaList, resolveSlackThreadStarter } from "../media.js";
+import { prepareSlackMessage } from "./prepare.js";
+
+const account: ResolvedSlackAccount = {
+  accountId: "default",
+  enabled: true,
+  botTokenSource: "config",
+  appTokenSource: "config",
+  config: {},
+} as ResolvedSlackAccount;
+
+const createContext = () => {
+  const slackCtx = createSlackMonitorContext({
+    cfg: {
+      agents: { defaults: { model: "anthropic/claude-opus-4-5", workspace: "/tmp/clawd" } },
+      channels: { slack: { enabled: true } },
+    } as ClawdbotConfig,
+    accountId: "default",
+    botToken: "token",
+    app: { client: {} } as App,
+    runtime: {} as RuntimeEnv,
+    botUserId: "B1",
+    teamId: "T1",
+    apiAppId: "A1",
+    historyLimit: 0,
+    sessionScope: "per-sender",
+    mainKey: "main",
+    dmEnabled: true,
+    dmPolicy: "open",
+    allowFrom: [],
+    groupDmEnabled: true,
+    groupDmChannels: [],
+    defaultRequireMention: true,
+    groupPolicy: "open",
+    useAccessGroups: false,
+    reactionMode: "off",
+    reactionAllowlist: [],
+    replyToMode: "off",
+    threadHistoryScope: "thread",
+    threadInheritParent: false,
+    slashCommand: {
+      enabled: false,
+      name: "clawd",
+      sessionPrefix: "slack:slash",
+      ephemeral: true,
+    },
+    textLimit: 4000,
+    ackReactionScope: "off",
+    mediaMaxBytes: 1024,
+    removeAckAfterReply: false,
+  });
+  slackCtx.resolveChannelName = async () => ({ name: "general", type: "channel" });
+  slackCtx.resolveUserName = async () => ({ name: "Alice" });
+  return slackCtx;
+};
+
+const mediaMock = vi.mocked(resolveSlackMediaList);
+const starterMock = vi.mocked(resolveSlackThreadStarter);
+
+beforeEach(() => {
+  mediaMock.mockReset();
+  starterMock.mockReset();
+  mediaMock.mockResolvedValue([]);
+  starterMock.mockResolvedValue(null);
+});
+
+describe("prepareSlackMessage thread media", () => {
+  it("hydrates root files for thread replies without attachments", async () => {
+    const ctx = createContext();
+    starterMock.mockResolvedValueOnce({
+      text: "",
+      userId: "U2",
+      ts: "171234.000",
+      files: [{ name: "root.pdf" }],
+    });
+    mediaMock.mockResolvedValueOnce([]).mockResolvedValueOnce([
+      {
+        path: "/tmp/root.pdf",
+        contentType: "application/pdf",
+        placeholder: "[Slack file: root.pdf]",
+      },
+    ]);
+
+    const message: SlackMessageEvent = {
+      type: "message",
+      channel: "C1",
+      channel_type: "channel",
+      text: "",
+      user: "U1",
+      ts: "171234.111",
+      thread_ts: "171234.000",
+    } as SlackMessageEvent;
+
+    const prepared = await prepareSlackMessage({
+      ctx,
+      account,
+      message,
+      opts: { source: "message", wasMentioned: true },
+    });
+
+    expect(prepared).not.toBeNull();
+    expect(prepared?.ctxPayload.RawBody).toBe("[Slack file: root.pdf]");
+    expect(prepared?.ctxPayload.MediaPath).toBe("/tmp/root.pdf");
+    expect(prepared?.ctxPayload.MediaPaths).toEqual(["/tmp/root.pdf"]);
+  });
+
+  it("emits MediaPaths for multiple attachments", async () => {
+    const ctx = createContext();
+    mediaMock.mockResolvedValueOnce([
+      {
+        path: "/tmp/a.png",
+        contentType: "image/png",
+        placeholder: "[Slack file: a.png]",
+      },
+      {
+        path: "/tmp/b.pdf",
+        contentType: "application/pdf",
+        placeholder: "[Slack file: b.pdf]",
+      },
+    ]);
+
+    const message: SlackMessageEvent = {
+      type: "message",
+      channel: "C1",
+      channel_type: "channel",
+      text: "hi",
+      user: "U1",
+      ts: "171234.111",
+      files: [{ name: "a.png" }, { name: "b.pdf" }],
+    } as SlackMessageEvent;
+
+    const prepared = await prepareSlackMessage({
+      ctx,
+      account,
+      message,
+      opts: { source: "message", wasMentioned: true },
+    });
+
+    expect(prepared?.ctxPayload.MediaPath).toBe("/tmp/a.png");
+    expect(prepared?.ctxPayload.MediaPaths).toEqual(["/tmp/a.png", "/tmp/b.pdf"]);
+    expect(prepared?.ctxPayload.MediaTypes).toEqual(["image/png", "application/pdf"]);
+    expect(prepared?.ctxPayload.MediaUrls).toEqual(["/tmp/a.png", "/tmp/b.pdf"]);
+  });
+
+  it("keeps file-only messages when downloads fail", async () => {
+    const ctx = createContext();
+    mediaMock.mockResolvedValueOnce([]);
+
+    const message: SlackMessageEvent = {
+      type: "message",
+      channel: "C1",
+      channel_type: "channel",
+      text: "",
+      user: "U1",
+      ts: "171234.111",
+      files: [{ name: "doc.txt" }],
+    } as SlackMessageEvent;
+
+    const prepared = await prepareSlackMessage({
+      ctx,
+      account,
+      message,
+      opts: { source: "message", wasMentioned: true },
+    });
+
+    expect(prepared).not.toBeNull();
+    expect(prepared?.ctxPayload.RawBody).toBe("[Slack file: doc.txt]");
+    expect(prepared?.ctxPayload.MediaPath).toBeUndefined();
+  });
+});

src/slack/monitor/message-handler/prepare.ts

@@ -39,7 +39,11 @@ import { resolveSlackAllowListMatch, resolveSlackUserAllowed } from "../allow-li
 import { resolveSlackEffectiveAllowFrom } from "../auth.js";
 import { resolveSlackChannelConfig } from "../channel-config.js";
 import { normalizeSlackChannelType, type SlackMonitorContext } from "../context.js";
-import { resolveSlackMedia, resolveSlackThreadStarter } from "../media.js";
+import {
+  resolveSlackFilePlaceholder,
+  resolveSlackMediaList,
+  resolveSlackThreadStarter,
+} from "../media.js";
 
 import type { PreparedSlackMessage } from "./types.js";
 
@@ -290,11 +294,7 @@ export async function prepareSlackMessage(params: {
     ctx.logger.info({ channel: message.channel, reason: "no-mention" }, "skipping channel message");
     if (ctx.historyLimit > 0) {
       const pendingText = (message.text ?? "").trim();
-      const fallbackFile = message.files?.[0]?.name
+      const fallbackFile = resolveSlackFilePlaceholder(message.files) ?? "";
-        ? `[Slack file: ${message.files[0].name}]`
-        : message.files?.length
-          ? "[Slack file]"
-          : "";
       const pendingBody = pendingText || fallbackFile;
       if (pendingBody) {
         recordPendingHistoryEntry({
@@ -313,13 +313,80 @@ export async function prepareSlackMessage(params: {
     return null;
   }
 
-  const media = await resolveSlackMedia({
+  const roomLabel = channelName ? `#${channelName}` : `#${message.channel}`;
+  const envelopeOptions = resolveEnvelopeFormatOptions(ctx.cfg);
+
+  const mediaList = await resolveSlackMediaList({
     files: message.files,
     token: ctx.botToken,
     maxBytes: ctx.mediaMaxBytes,
   });
-  const rawBody = (message.text ?? "").trim() || media?.placeholder || "";
+  const messageFilePlaceholder = resolveSlackFilePlaceholder(message.files);
+
+  let threadStarter: Awaited<ReturnType<typeof resolveSlackThreadStarter>> = null;
+  let threadStarterBody: string | undefined;
+  let threadLabel: string | undefined;
+  let threadStarterMediaList: Awaited<ReturnType<typeof resolveSlackMediaList>> = [];
+  if (isThreadReply && threadTs) {
+    threadStarter = await resolveSlackThreadStarter({
+      channelId: message.channel,
+      threadTs,
+      client: ctx.app.client,
+    });
+    if (threadStarter?.text) {
+      const starterUser = threadStarter.userId
+        ? await ctx.resolveUserName(threadStarter.userId)
+        : null;
+      const starterName = starterUser?.name ?? threadStarter.userId ?? "Unknown";
+      const starterWithId = `${threadStarter.text}\n[slack message id: ${
+        threadStarter.ts ?? threadTs
+      } channel: ${message.channel}]`;
+      threadStarterBody = formatThreadStarterEnvelope({
+        channel: "Slack",
+        author: starterName,
+        timestamp: threadStarter.ts ? Math.round(Number(threadStarter.ts) * 1000) : undefined,
+        body: starterWithId,
+        envelope: envelopeOptions,
+      });
+      const snippet = threadStarter.text.replace(/\s+/g, " ").slice(0, 80);
+      threadLabel = `Slack thread ${roomLabel}${snippet ? `: ${snippet}` : ""}`;
+    } else {
+      threadLabel = `Slack thread ${roomLabel}`;
+    }
+
+    if (!message.files?.length && threadStarter?.files?.length) {
+      threadStarterMediaList = await resolveSlackMediaList({
+        files: threadStarter.files,
+        token: ctx.botToken,
+        maxBytes: ctx.mediaMaxBytes,
+      });
+      if (threadStarterMediaList.length > 0) {
+        logVerbose(
+          `slack: hydrated thread starter files (${threadStarterMediaList.length}) from root message`,
+        );
+      }
+    }
+  }
+
+  const threadStarterFilePlaceholder =
+    !message.files?.length && threadStarter?.files?.length
+      ? resolveSlackFilePlaceholder(threadStarter.files)
+      : undefined;
+
+  const effectiveMediaList = mediaList.length > 0 ? mediaList : threadStarterMediaList;
+  const effectiveMedia = effectiveMediaList[0];
+
+  const rawBody =
+    (message.text ?? "").trim() ||
+    messageFilePlaceholder ||
+    threadStarterFilePlaceholder ||
+    effectiveMedia?.placeholder ||
+    "";
   if (!rawBody) return null;
+  const mediaPaths = effectiveMediaList.map((entry) => entry.path);
+  const mediaTypes = effectiveMediaList
+    .map((entry) => entry.contentType)
+    .filter(Boolean) as string[];
 
   const ackReaction = resolveAckReaction(cfg, route.agentId);
   const ackReactionValue = ackReaction ?? "";
@@ -353,7 +420,6 @@ export async function prepareSlackMessage(params: {
         )
       : null;
 
-  const roomLabel = channelName ? `#${channelName}` : `#${message.channel}`;
   const preview = rawBody.replace(/\s+/g, " ").slice(0, 160);
   const inboundLabel = isDirectMessage
     ? `Slack DM from ${senderName}`
@@ -380,7 +446,6 @@ export async function prepareSlackMessage(params: {
   const storePath = resolveStorePath(ctx.cfg.session?.store, {
     agentId: route.agentId,
   });
-  const envelopeOptions = resolveEnvelopeFormatOptions(ctx.cfg);
   const previousTimestamp = readSessionUpdatedAt({
     storePath,
     sessionKey: route.sessionKey,
@@ -431,33 +496,6 @@ export async function prepareSlackMessage(params: {
   ].filter((entry): entry is string => Boolean(entry));
   const groupSystemPrompt =
     systemPromptParts.length > 0 ? systemPromptParts.join("\n\n") : undefined;
-
-  let threadStarterBody: string | undefined;
-  let threadLabel: string | undefined;
-  if (isThreadReply && threadTs) {
-    const starter = await resolveSlackThreadStarter({
-      channelId: message.channel,
-      threadTs,
-      client: ctx.app.client,
-    });
-    if (starter?.text) {
-      const starterUser = starter.userId ? await ctx.resolveUserName(starter.userId) : null;
-      const starterName = starterUser?.name ?? starter.userId ?? "Unknown";
-      const starterWithId = `${starter.text}\n[slack message id: ${starter.ts ?? threadTs} channel: ${message.channel}]`;
-      threadStarterBody = formatThreadStarterEnvelope({
-        channel: "Slack",
-        author: starterName,
-        timestamp: starter.ts ? Math.round(Number(starter.ts) * 1000) : undefined,
-        body: starterWithId,
-        envelope: envelopeOptions,
-      });
-      const snippet = starter.text.replace(/\s+/g, " ").slice(0, 80);
-      threadLabel = `Slack thread ${roomLabel}${snippet ? `: ${snippet}` : ""}`;
-    } else {
-      threadLabel = `Slack thread ${roomLabel}`;
-    }
-  }
-
   const ctxPayload = finalizeInboundContext({
     Body: combinedBody,
     RawBody: rawBody,
@@ -483,9 +521,12 @@ export async function prepareSlackMessage(params: {
     ThreadLabel: threadLabel,
     Timestamp: message.ts ? Math.round(Number(message.ts) * 1000) : undefined,
     WasMentioned: isRoomish ? effectiveWasMentioned : undefined,
-    MediaPath: media?.path,
+    MediaPath: effectiveMedia?.path,
-    MediaType: media?.contentType,
+    MediaType: effectiveMedia?.contentType,
-    MediaUrl: media?.path,
+    MediaUrl: effectiveMedia?.path,
+    MediaPaths: mediaPaths.length > 0 ? mediaPaths : undefined,
+    MediaUrls: mediaPaths.length > 0 ? mediaPaths : undefined,
+    MediaTypes: mediaTypes.length > 0 ? mediaTypes : undefined,
     CommandAuthorized: commandAuthorized,
     OriginatingChannel: "slack" as const,
     OriginatingTo: slackTo,