From aa82e90aec06509c0b837eacc1b2096edf855518 Mon Sep 17 00:00:00 2001
From: "sentry-junior[bot]"
 <264270552+sentry-junior[bot]@users.noreply.github.com>
Date: Wed, 3 Jun 2026 15:33:54 +0000
Subject: [PATCH] fix(mrkdwn): convert Slack angle-bracket links to Markdown
 for markdown block
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The body is delivered as a Slack `markdown` block, which expects standard
Markdown links ([label](url)). Using Slack mrkdwn angle-bracket syntax
(<URL>) collides with bold markers and produces malformed output like
**<https://url**> where the closing ** is absorbed inside the angle
brackets and Slack parses https://url** as the URL.

Normalize in three passes:
1. Repair malformed bold-wrapped angle autolinks: **<URL**> → [URL](URL)
2. Convert Slack labeled links: <URL|label> → [label](URL)
3. Convert remaining angle autolinks: <URL> → [URL](URL)

Refs: https://sentry.slack.com/archives/C03USURCFBJ/p1780496988280239

Co-authored-by: David Cramer <david@sentry.io>
---
 packages/junior/src/chat/slack/mrkdwn.ts      | 19 ++++++++
 .../junior/tests/unit/misc/output.test.ts     | 46 +++++++++++++++++++
 2 files changed, 65 insertions(+)

diff --git a/packages/junior/src/chat/slack/mrkdwn.ts b/packages/junior/src/chat/slack/mrkdwn.ts
index be155b4d1..85af040df 100644
--- a/packages/junior/src/chat/slack/mrkdwn.ts
+++ b/packages/junior/src/chat/slack/mrkdwn.ts
@@ -58,6 +58,25 @@ export function ensureBlockSpacing(text: string): string {
 export function renderSlackMrkdwn(text: string): string {
   let normalized = text.replace(/\r\n?/g, "\n").replace(/[ \t]+$/gm, "");
   normalized = ensureBlockSpacing(normalized);
+  // The body is sent as a Slack `markdown` block, which expects standard
+  // Markdown links ([label](url)), not Slack mrkdwn angle-bracket syntax
+  // (<URL> / <URL|label>). Convert to explicit Markdown links so the block
+  // renders them correctly and bold markers (**) can never collide with the
+  // angle brackets and corrupt the URL.
+  //
+  // Pass 1: repair malformed bold-wrapped angle autolinks produced by the
+  // model: **<https://url**> → [https://url](https://url)
+  normalized = normalized.replace(
+    /\*\*<(https?:\/\/[^*>\s]+)\*\*>/g,
+    "[$1]($1)",
+  );
+  // Pass 2: Slack labeled links → Markdown: <https://url|label> → [label](https://url)
+  normalized = normalized.replace(
+    /<(https?:\/\/[^|>\s]+)\|([^>]+)>/g,
+    "[$2]($1)",
+  );
+  // Pass 3: remaining angle autolinks → explicit Markdown links: <https://url> → [https://url](https://url)
+  normalized = normalized.replace(/<(https?:\/\/[^>\s]+)>/g, "[$1]($1)");
   return normalized.replace(/\n{3,}/g, "\n\n").trim();
 }
 
diff --git a/packages/junior/tests/unit/misc/output.test.ts b/packages/junior/tests/unit/misc/output.test.ts
index 507aacd8e..221ed2025 100644
--- a/packages/junior/tests/unit/misc/output.test.ts
+++ b/packages/junior/tests/unit/misc/output.test.ts
@@ -15,6 +15,52 @@ describe("renderSlackMrkdwn", () => {
       "one\n\n- item a\n- item b\n\ntwo",
     );
   });
+
+  it("converts Slack angle-bracket URL to explicit Markdown link", () => {
+    expect(
+      renderSlackMrkdwn("See <https://example.com> for details."),
+    ).toBe("See [https://example.com](https://example.com) for details.");
+  });
+
+  it("converts Slack labeled links to Markdown format", () => {
+    expect(
+      renderSlackMrkdwn("<https://github.com/org/repo/pull/1|PR #1>"),
+    ).toBe("[PR #1](https://github.com/org/repo/pull/1)");
+  });
+
+  it("resolves bold+angle-bracket collision that broke GitHub PR links", () => {
+    // The model generated **<https://url**> — closing ** absorbed inside the
+    // angle brackets. Pass 1 catches this and converts to [url](url).
+    expect(
+      renderSlackMrkdwn(
+        "**<https://github.com/getsentry/sentry/pull/116765**>",
+      ),
+    ).toBe(
+      "[https://github.com/getsentry/sentry/pull/116765](https://github.com/getsentry/sentry/pull/116765)",
+    );
+  });
+
+  it("converts multiple angle-bracket URLs in one message", () => {
+    expect(
+      renderSlackMrkdwn(
+        "PR1: <https://github.com/org/repo/pull/1> and PR2: <https://github.com/org/repo/pull/2>",
+      ),
+    ).toBe(
+      "PR1: [https://github.com/org/repo/pull/1](https://github.com/org/repo/pull/1) and PR2: [https://github.com/org/repo/pull/2](https://github.com/org/repo/pull/2)",
+    );
+  });
+
+  it("leaves Markdown links unchanged", () => {
+    expect(
+      renderSlackMrkdwn("**[PR #123](https://github.com/org/repo/pull/123)**"),
+    ).toBe("**[PR #123](https://github.com/org/repo/pull/123)**");
+  });
+
+  it("leaves plain bold text unchanged", () => {
+    expect(renderSlackMrkdwn("**Root cause** is here.")).toBe(
+      "**Root cause** is here.",
+    );
+  });
 });
 
 describe("buildSlackOutputMessage", () => {