Render links reliably in Slack messages

README.md

@@ -299,7 +299,7 @@ agent-slack message edit "#general" "Updated text" --workspace "myteam" --ts "17
 agent-slack message delete "#general" --workspace "myteam" --ts "1770165109.628379"
 ```
 
-`message edit` and ordinary `message send` calls convert bullet/numbered lists to Slack native rich text. `message send --blocks` uses the supplied blocks instead, while `message send --attach` sends its initial comment as plain text without automatic list conversion. Inside auto-converted lists, inline mentions, broadcasts, emoji shortcodes, `<#C...>` channel references, and Slack manual links such as `<https://example.com/pull/42|PR #42>` are preserved as Slack elements. CommonMark links such as `[PR #42](https://example.com/pull/42)` are not converted into labeled link elements.
+`message edit` and ordinary `message send` calls normalize links and convert bullet/numbered lists to Slack native rich text. `message send --blocks` uses the supplied blocks instead, while `message send --attach` sends its initial comment as plain text without automatic list conversion. Links may be bare HTTP(S) URLs or use Markdown (`[PR #42](https://example.com/pull/42)`) or Slack (`<https://example.com/pull/42|PR #42>`) syntax. Inside auto-converted lists, links, inline mentions, broadcasts, emoji shortcodes, and `<#C...>` channel references become Slack elements.
 
 Send options for `message send`:
 

skills/agent-slack/SKILL.md

@@ -37,7 +37,7 @@ Named `later remind --in` values such as `tomorrow` or `monday` also use the exe
 
 Use `--no-unfurl` with `message send` or `message compose` when the user wants Slack link and media previews suppressed. It cannot be combined with `message send --attach`.
 
-Ordinary `message send` and `message edit` calls auto-convert lists. `message send --blocks` and `message edit --blocks` use supplied Block Kit blocks, while `message send --attach` sends its initial comment without automatic list conversion. Inside auto-converted lists, use Slack's `<URL|label>` syntax because CommonMark `[label](URL)` links are not converted into labeled link elements.
+Ordinary `message send` and `message edit` calls normalize bare HTTP(S), `[label](URL)`, and `<URL|label>` links and auto-convert lists. `message send --blocks` and `message edit --blocks` use supplied Block Kit blocks, while `message send --attach` sends its initial comment without automatic list conversion.
 
 Slack-native drafts (`message draft list|create|update|delete`) manage drafts that appear in the user's Slack client; `create` posts nothing. `create` and `update` accept repeatable `--attach <path>`; on `update` the files are added to the draft's existing attachments rather than replacing them. They use undocumented session endpoints and require browser-style auth (xoxc/xoxd).
 

src/slack/format-outbound.ts

@@ -1,3 +1,5 @@
+import { markdownLinksToSlackMrkdwn } from "./markdown-inline.ts";
+
 /**
  * Prepare user-authored text for Slack's `chat.postMessage` / `chat.update`.
  *
@@ -8,18 +10,23 @@
  *    `<!here>` / `<!channel>` / `<!everyone>`
  *
  * Humans (and LLMs piping text into the CLI) commonly write `@U123` and
- * raw `&`/`<`/`>` — this helper normalizes that to what Slack expects,
- * while leaving already-well-formed Slack tokens intact.
+ * `[label](https://example.com)` links as well as raw `&`/`<`/`>` — this
+ * helper normalizes those to what Slack expects, while leaving
+ * already-well-formed Slack tokens intact.
  */
 export function formatOutboundSlackText(text: string): string {
   if (!text) {
     return "";
   }
 
+  // Slack does not understand CommonMark links in message text. Normalize the
+  // common inline form while leaving images, escaped links, and code alone.
+  let out = markdownLinksToSlackMrkdwn(text);
+
   // Protect already-formatted Slack tokens so `<`/`>` inside them aren't escaped.
   const stash: string[] = [];
-  let out = text.replace(
-    /<(?:@[UWB][A-Z0-9]+(?:\|[^>]*)?|#[CG][A-Z0-9]+(?:\|[^>]*)?|!subteam\^[A-Z0-9]+(?:\|[^>]*)?|![a-zA-Z]+(?:\|[^>]*)?|(?:https?:\/\/|mailto:)[^>]+)>/g,
+  out = out.replace(
+    /<(?:@[UWB][A-Z0-9]+(?:\|[^>]*)?|#[CG][A-Z0-9]+(?:\|[^>]*)?|!subteam\^[A-Z0-9]+(?:\|[^>]*)?|![a-zA-Z]+(?:\|[^>]*)?|(?:[Hh][Tt][Tt][Pp][Ss]?:\/\/|[Mm][Aa][Ii][Ll][Tt][Oo]:)[^>]+)>/g,
     (m) => {
       stash.push(m);
       return `\u0000${stash.length - 1}\u0000`;