fix(slack): Preserve hyperlink URLs in assistant context

packages/junior/src/chat/message-text.ts

@@ -0,0 +1,39 @@
+import type { FormattedContent } from "chat";
+
+interface AstNode {
+  type: string;
+  value?: string;
+  url?: string;
+  children?: AstNode[];
+}
+
+/** Extract plain text from a message AST, preserving hyperlink URLs as `[text](url)`. */
+export function extractTextPreservingLinks(ast: FormattedContent): string {
+  return visitNode(ast as AstNode).trim();
+}
+
+const BLOCK_TYPES = new Set([
+  "root",
+  "paragraph",
+  "list",
+  "listItem",
+  "blockquote",
+  "heading",
+]);
+
+function visitNode(node: AstNode): string {
+  if (
+    node.type === "text" ||
+    node.type === "inlineCode" ||
+    node.type === "code"
+  )
+    return node.value ?? "";
+  if (node.type === "link") {
+    const childText = (node.children ?? []).map(visitNode).join("");
+    return childText === node.url
+      ? node.url
+      : `[${childText}](${node.url ?? ""})`;
+  }
+  const separator = BLOCK_TYPES.has(node.type) ? "\n" : "";
+  return (node.children ?? []).map(visitNode).join(separator);
+}

packages/junior/src/chat/runtime/reply-executor.ts

@@ -1,4 +1,5 @@
 import type { Message, SentMessage, Thread } from "chat";
+import { extractTextPreservingLinks } from "@/chat/message-text";
 import type { SlackAdapter } from "@chat-adapter/slack";
 import { botConfig } from "@/chat/config";
 import { isExplicitChannelPostIntent } from "@/chat/services/channel-intent";
@@ -143,10 +144,13 @@ export function createReplyToThread(deps: ReplyExecutorDeps) {
         modelId: botConfig.modelId,
       },
       async () => {
-        const userText = stripLeadingBotMention(message.text, {
-          stripLeadingSlackMentionToken:
-            options.explicitMention || Boolean(message.isMention),
-        });
+        const userText = stripLeadingBotMention(
+          extractTextPreservingLinks(message.formatted),
+          {
+            stripLeadingSlackMentionToken:
+              options.explicitMention || Boolean(message.isMention),
+          },
+        );
         const explicitChannelPostIntent = isExplicitChannelPostIntent(userText);
 
         const preparedState =

packages/junior/src/chat/runtime/slack-runtime.ts

@@ -1,5 +1,6 @@
 import type { Message, Thread } from "chat";
 import { getSubscribedReplyPreflightDecision } from "@/chat/services/subscribed-decision";
+import { extractTextPreservingLinks } from "@/chat/message-text";
 import { isRetryableTurnError } from "@/chat/runtime/turn";
 import type { ErrorReference } from "@/chat/logging";
 import { getSlackErrorObservabilityAttributes } from "@/chat/runtime/thread-context";
@@ -347,7 +348,7 @@ export function createSlackTurnRuntime<
         const threadId = deps.getThreadId(thread, message);
         const channelId = deps.getChannelId(thread, message);
         const runId = deps.getRunId(thread, message);
-        const rawUserText = message.text;
+        const rawUserText = extractTextPreservingLinks(message.formatted);
         const userText = deps.stripLeadingBotMention(rawUserText, {
           stripLeadingSlackMentionToken: Boolean(message.isMention),
         });

packages/junior/src/chat/runtime/thread-context.ts

@@ -21,7 +21,7 @@ export function stripLeadingBotMention(
 
   let next = text;
   if (options.stripLeadingSlackMentionToken) {
-    next = next.replace(/^\s*<@[^>]+>[\s,:-]*/, "").trim();
+    next = next.replace(/^\s*@[A-Z][A-Z0-9_]+\b[\s,:-]*/i, "").trim();
   }
 
   const mentionByNameRe = new RegExp(

packages/junior/src/chat/services/conversation-memory.ts

@@ -1,4 +1,5 @@
 import type { Message, Thread } from "chat";
+import { extractTextPreservingLinks } from "@/chat/message-text";
 import { botConfig } from "@/chat/config";
 import { completeText } from "@/chat/pi/client";
 import type {
@@ -390,7 +391,9 @@ export const generateThreadTitle =
 function createConversationMessageFromSdkMessage(
   entry: Message,
 ): ConversationMessage | null {
-  const rawText = normalizeConversationText(entry.text);
+  const rawText = normalizeConversationText(
+    extractTextPreservingLinks(entry.formatted),
+  );
   if (!rawText) {
     return null;
   }

packages/junior/tests/fixtures/slack-harness.ts

@@ -1,10 +1,11 @@
-import type {
-  Adapter,
-  Author,
-  Channel,
-  Message,
-  SentMessage,
-  Thread,
+import {
+  type Adapter,
+  type Author,
+  type Channel,
+  type Message,
+  type SentMessage,
+  type Thread,
+  parseMarkdown,
 } from "chat";
 
 // ── Helpers ──────────────────────────────────────────────────────────
@@ -15,6 +16,16 @@ function parseChannelFromThreadId(threadId: string): string | undefined {
   return undefined;
 }
 
+/** Convert Slack mrkdwn syntax to standard markdown for AST parsing. */
+function slackTextToMarkdown(text: string): string {
+  return text
+    .replace(/<@([A-Z0-9_]+)\|([^<>]+)>/g, "@$2")
+    .replace(/<@([A-Z0-9_]+)>/g, "@$1")
+    .replace(/<#[A-Z0-9_]+\|([^<>]+)>/g, "#$1")
+    .replace(/<(https?:\/\/[^|<>]+)\|([^<>]+)>/g, "[$2]($1)")
+    .replace(/<(https?:\/\/[^<>]+)>/g, "$1");
+}
+
 // ── Test Author ──────────────────────────────────────────────────────
 
 const defaultAuthor: Author = {
@@ -52,7 +63,7 @@ export function createTestMessage(args: {
     isMention: args.isMention,
     attachments: args.attachments ?? [],
     metadata: { dateSent: new Date(), edited: false },
-    formatted: { type: "root", children: [] },
+    formatted: parseMarkdown(slackTextToMarkdown(args.text ?? "hello")),
     raw: args.raw ?? {
       ...(inferredChannel ? { channel: inferredChannel } : {}),
       ...(inferredTs ? { ts: inferredTs, thread_ts: inferredTs } : {}),

packages/junior/tests/integration/slack/message-content-behavior.test.ts

@@ -103,7 +103,49 @@ describe("Slack behavior: message content", () => {
     await slackRuntime.handleNewMention(thread, message);
 
     expect(calls).toHaveLength(1);
-    expect(calls[0]?.prompt).toContain("message <@U_ONCALL> after deploy");
+    expect(calls[0]?.prompt).toContain("message @U_ONCALL after deploy");
+  });
+
+  it("preserves hyperlink URLs from Slack mrkdwn in user content", async () => {
+    const calls: CapturedCall[] = [];
+
+    const { slackRuntime } = createTestChatRuntime({
+      services: {
+        replyExecutor: {
+          generateAssistantReply: async (prompt) => {
+            calls.push({ prompt });
+            return {
+              text: "Done.",
+              diagnostics: {
+                assistantMessageCount: 1,
+                modelId: "fake-agent-model",
+                outcome: "success",
+                toolCalls: [],
+                toolErrorCount: 0,
+                toolResultCount: 0,
+                usedPrimaryText: true,
+              },
+            };
+          },
+        },
+      },
+    });
+
+    const thread = createTestThread({ id: "slack:C_BEHAVIOR:1700005004.000" });
+    const message = createTestMessage({
+      id: "m-content-links",
+      text: "<@U_APP> check <https://github.com/foo/bar/pull/1|this PR> please",
+      isMention: true,
+      threadId: thread.id,
+      author: { userId: "U_TESTER" },
+    });
+
+    await slackRuntime.handleNewMention(thread, message);
+
+    expect(calls).toHaveLength(1);
+    expect(calls[0]?.prompt).toContain(
+      "[this PR](https://github.com/foo/bar/pull/1)",
+    );
   });
 
   it("does not invoke the agent for self-authored mention messages", async () => {

packages/junior/tests/unit/slack/slack-runtime.test.ts

@@ -273,7 +273,7 @@ describe("createSlackTurnRuntime", () => {
       await runtime.handleSubscribedMessage(thread, message);
 
       expect(deps.stripLeadingBotMention).toHaveBeenCalledWith(
-        "<@U123> stripped text",
+        "@U123 stripped text",
         { stripLeadingSlackMentionToken: true },
       );
       expect(deps.prepareTurnState).toHaveBeenCalledWith(