fix(setup): add missing SLACK_HOME_CHANNEL prompt to _setup_slack()

_setup_slack() was the only platform setup function that did not prompt
for a home channel. All four sibling setups (_setup_telegram,
_setup_discord, _setup_mattermost, _setup_bluebubbles) close with an
identical home-channel block, and setup_gateway() already checks for
SLACK_HOME_CHANNEL presence at the end of the wizard — but the value
was never collected, leaving cron delivery and cross-platform
notifications silently broken for Slack after a fresh hermes setup run.

Add the standard home-channel prompt at the end of _setup_slack(),
symmetric with the Discord implementation. Add two unit tests that
verify the prompt is saved when provided and skipped when left blank.

hermes_cli/setup.py

@@ -2047,6 +2047,16 @@ def _setup_slack():
         print_warning("⚠️  No Slack allowlist set - unpaired users will be denied by default.")
         print_info("   Set SLACK_ALLOW_ALL_USERS=true or GATEWAY_ALLOW_ALL_USERS=true only if you intentionally want open workspace access.")
 
+    print()
+    print_info("📬 Home Channel: where Hermes delivers cron job results,")
+    print_info("   cross-platform messages, and notifications.")
+    print_info("   To get a channel ID: open the channel in Slack, then right-click")
+    print_info("   the channel name → Copy link — the ID starts with C (e.g. C01ABC2DE3F).")
+    print_info("   You can also set this later by typing /set-home in a Slack channel.")
+    home_channel = prompt("Home channel ID (leave empty to set later with /set-home)")
+    if home_channel:
+        save_env_value("SLACK_HOME_CHANNEL", home_channel.strip())
+
 
 def _write_slack_manifest_and_instruct():
     """Generate the Slack manifest, write it under HERMES_HOME, and print

tests/hermes_cli/test_setup.py

@@ -613,3 +613,35 @@ def test_offer_launch_chat_falls_back_to_module(monkeypatch):
         setup_mod._offer_launch_chat()
 
     assert exec_calls == [(sys.executable, [sys.executable, "-m", "hermes_cli.main", "chat"])]
+
+
+def test_setup_slack_saves_home_channel(monkeypatch):
+    """_setup_slack() saves SLACK_HOME_CHANNEL when the user provides one."""
+    saved = {}
+    prompts = iter(["xoxb-test-token", "xapp-test-token", "", "C01ABC2DE3F"])
+
+    monkeypatch.setattr(setup_mod, "get_env_value", lambda key: "")
+    monkeypatch.setattr(setup_mod, "save_env_value", lambda k, v: saved.update({k: v}))
+    monkeypatch.setattr(setup_mod, "prompt", lambda *_a, **_kw: next(prompts))
+    monkeypatch.setattr(setup_mod, "prompt_yes_no", lambda *_a, **_kw: False)
+    monkeypatch.setattr(setup_mod, "_write_slack_manifest_and_instruct", lambda: None)
+
+    setup_mod._setup_slack()
+
+    assert saved.get("SLACK_HOME_CHANNEL") == "C01ABC2DE3F"
+
+
+def test_setup_slack_home_channel_empty_not_saved(monkeypatch):
+    """_setup_slack() does not save SLACK_HOME_CHANNEL when left blank."""
+    saved = {}
+    prompts = iter(["xoxb-test-token", "xapp-test-token", "", ""])
+
+    monkeypatch.setattr(setup_mod, "get_env_value", lambda key: "")
+    monkeypatch.setattr(setup_mod, "save_env_value", lambda k, v: saved.update({k: v}))
+    monkeypatch.setattr(setup_mod, "prompt", lambda *_a, **_kw: next(prompts))
+    monkeypatch.setattr(setup_mod, "prompt_yes_no", lambda *_a, **_kw: False)
+    monkeypatch.setattr(setup_mod, "_write_slack_manifest_and_instruct", lambda: None)
+
+    setup_mod._setup_slack()
+
+    assert "SLACK_HOME_CHANNEL" not in saved