test: expand slash command autocomplete coverage (PR #645 follow-up)

- Fix failing test: use display_text/display_meta_text instead of str()
  on prompt_toolkit FormattedText objects
- Add regression guard: EXPECTED_COMMANDS set ensures no command
  silently disappears from the shared dict
- Add edge case tests: non-slash input, empty input, partial vs exact
  match trailing space, builtin display_meta content
- Add skill provider tests: None provider, exception swallowing,
  description truncation at 50 chars, missing description fallback,
  exact-match trailing space on skill commands
- Total: 15 tests (up from 4)

tests/hermes_cli/test_commands.py

@@ -6,6 +6,15 @@ from prompt_toolkit.document import Document
 from hermes_cli.commands import COMMANDS, SlashCommandCompleter
 
 
+# All commands that must be present in the shared COMMANDS dict.
+EXPECTED_COMMANDS = {
+    "/help", "/tools", "/toolsets", "/model", "/prompt", "/personality",
+    "/clear", "/history", "/new", "/reset", "/retry", "/undo", "/save",
+    "/config", "/cron", "/skills", "/platforms", "/verbose", "/compress",
+    "/usage", "/insights", "/paste", "/reload-mcp", "/quit",
+}
+
+
 def _completions(completer: SlashCommandCompleter, text: str):
     return list(
         completer.get_completions(
@@ -17,11 +26,22 @@ def _completions(completer: SlashCommandCompleter, text: str):
 
 class TestCommands:
     def test_shared_commands_include_cli_specific_entries(self):
+        """Entries that previously only existed in cli.py are now in the shared dict."""
         assert COMMANDS["/paste"] == "Check clipboard for an image and attach it"
         assert COMMANDS["/reload-mcp"] == "Reload MCP servers from config.yaml"
 
+    def test_all_expected_commands_present(self):
+        """Regression guard — every known command must appear in the shared dict."""
+        assert set(COMMANDS.keys()) == EXPECTED_COMMANDS
+
+    def test_every_command_has_nonempty_description(self):
+        for cmd, desc in COMMANDS.items():
+            assert isinstance(desc, str) and len(desc) > 0, f"{cmd} has empty description"
+
 
 class TestSlashCommandCompleter:
+    # -- basic prefix completion -----------------------------------------
+
     def test_builtin_prefix_completion_uses_shared_registry(self):
         completions = _completions(SlashCommandCompleter(), "/re")
         texts = {item.text for item in completions}
@@ -30,11 +50,33 @@ class TestSlashCommandCompleter:
         assert "retry" in texts
         assert "reload-mcp" in texts
 
+    def test_builtin_completion_display_meta_shows_description(self):
+        completions = _completions(SlashCommandCompleter(), "/help")
+        assert len(completions) == 1
+        assert completions[0].display_meta_text == "Show this help message"
+
+    # -- exact-match trailing space --------------------------------------
+
     def test_exact_match_completion_adds_trailing_space(self):
         completions = _completions(SlashCommandCompleter(), "/help")
 
         assert [item.text for item in completions] == ["help "]
 
+    def test_partial_match_does_not_add_trailing_space(self):
+        completions = _completions(SlashCommandCompleter(), "/hel")
+
+        assert [item.text for item in completions] == ["help"]
+
+    # -- non-slash input returns nothing ---------------------------------
+
+    def test_no_completions_for_non_slash_input(self):
+        assert _completions(SlashCommandCompleter(), "help") == []
+
+    def test_no_completions_for_empty_input(self):
+        assert _completions(SlashCommandCompleter(), "") == []
+
+    # -- skill commands via provider ------------------------------------
+
     def test_skill_commands_are_completed_from_provider(self):
         completer = SlashCommandCompleter(
             skill_commands_provider=lambda: {
@@ -46,5 +88,57 @@ class TestSlashCommandCompleter:
 
         assert len(completions) == 1
         assert completions[0].text == "gif-search"
-        assert str(completions[0].display) == "/gif-search"
-        assert "⚡ Search for GIFs across providers" == str(completions[0].display_meta)
+        assert completions[0].display_text == "/gif-search"
+        assert completions[0].display_meta_text == "⚡ Search for GIFs across providers"
+
+    def test_skill_exact_match_adds_trailing_space(self):
+        completer = SlashCommandCompleter(
+            skill_commands_provider=lambda: {
+                "/gif-search": {"description": "Search for GIFs"},
+            }
+        )
+
+        completions = _completions(completer, "/gif-search")
+
+        assert len(completions) == 1
+        assert completions[0].text == "gif-search "
+
+    def test_no_skill_provider_means_no_skill_completions(self):
+        """Default (None) provider should not blow up or add completions."""
+        completer = SlashCommandCompleter()
+        completions = _completions(completer, "/gif")
+        # /gif doesn't match any builtin command
+        assert completions == []
+
+    def test_skill_provider_exception_is_swallowed(self):
+        """A broken provider should not crash autocomplete."""
+        completer = SlashCommandCompleter(
+            skill_commands_provider=lambda: (_ for _ in ()).throw(RuntimeError("boom")),
+        )
+        # Should return builtin matches only, no crash
+        completions = _completions(completer, "/he")
+        texts = {item.text for item in completions}
+        assert "help" in texts
+
+    def test_skill_description_truncated_at_50_chars(self):
+        long_desc = "A" * 80
+        completer = SlashCommandCompleter(
+            skill_commands_provider=lambda: {
+                "/long-skill": {"description": long_desc},
+            }
+        )
+        completions = _completions(completer, "/long")
+        assert len(completions) == 1
+        meta = completions[0].display_meta_text
+        # "⚡ " prefix + 50 chars + "..."
+        assert meta == f"⚡ {'A' * 50}..."
+
+    def test_skill_missing_description_uses_fallback(self):
+        completer = SlashCommandCompleter(
+            skill_commands_provider=lambda: {
+                "/no-desc": {},
+            }
+        )
+        completions = _completions(completer, "/no-desc")
+        assert len(completions) == 1
+        assert "Skill command" in completions[0].display_meta_text