feat(banner): size skills display to terminal width instead of fixed 8/47

Salvaged from #40273; re-verified on main, tightened, tested.

Co-authored-by: liuhao1024 <liuhao1024@users.noreply.github.com>

hermes_cli/banner.py

@@ -804,18 +804,34 @@ def build_welcome_banner(console: "Console", model: str, cwd: str,
         skills_by_category = {}
         total_skills = 0
 
+    # Dynamically size skills display based on terminal width.
+    # Rich grid with 2 columns; right column gets roughly 60% of terminal.
+    _term_cols = shutil.get_terminal_size().columns
+    _right_col_width = max(int(_term_cols * 0.6) - 10, 30)
+
     if not _skills_enabled:
         right_lines.append(f"[dim {dim}]Skills toolset disabled[/]")
     elif skills_by_category:
         for category in sorted(skills_by_category.keys()):
             skill_names = sorted(skills_by_category[category])
-            if len(skill_names) > 8:
-                display_names = skill_names[:8]
-                skills_str = ", ".join(display_names) + f" +{len(skill_names) - 8} more"
-            else:
-                skills_str = ", ".join(skill_names)
-            if len(skills_str) > 50:
-                skills_str = skills_str[:47] + "..."
+            # Account for "category: " prefix
+            _prefix_len = len(category) + 2
+            _avail = max(_right_col_width - _prefix_len, 20)
+            # Accumulate skills until we run out of space
+            parts, length = [], 0
+            for i, name in enumerate(skill_names):
+                _sep = ", " if parts else ""
+                _needed = len(_sep) + len(name)
+                # Estimate indicator size IF we were to add this skill then stop
+                _after = len(skill_names) - (i + 1)  # remaining after adding this
+                _ind_len = len(f", +{_after} more") if _after > 0 else 0
+                if parts and length + _needed + _ind_len > _avail:
+                    remaining = len(skill_names) - len(parts)
+                    parts.append(f"+{remaining} more")
+                    break
+                parts.append(name)
+                length += _needed
+            skills_str = ", ".join(parts)
             right_lines.append(f"[dim {dim}]{category}:[/] [{text}]{skills_str}[/]")
     else:
         right_lines.append(f"[dim {dim}]No skills installed[/]")

tests/hermes_cli/test_banner_skills_width.py

@@ -0,0 +1,77 @@
+"""Tests for banner skills display — terminal-width-aware truncation."""
+
+import os
+from unittest.mock import patch
+
+from rich.console import Console
+
+import hermes_cli.banner as banner
+import model_tools
+import tools.mcp_tool
+
+
+def _build_banner_with_skills(skills_by_category, term_width=160):
+    """Helper: build banner with given skills and return captured output."""
+    with (
+        patch.object(
+            model_tools,
+            "check_tool_availability",
+            return_value=([], []),
+        ),
+        patch.object(banner, "get_available_skills", return_value=skills_by_category),
+        patch.object(banner, "get_update_result", return_value=None),
+        patch.object(tools.mcp_tool, "get_mcp_status", return_value=[]),
+        patch("shutil.get_terminal_size", return_value=os.terminal_size((term_width, 50))),
+    ):
+        console = Console(
+            record=True, force_terminal=False, color_system=None, width=term_width
+        )
+        banner.build_welcome_banner(
+            console=console,
+            model="anthropic/test-model",
+            cwd="/tmp/project",
+            tools=[],
+        )
+        return console.export_text()
+
+
+def test_wide_terminal_shows_more_than_8_skills():
+    """A wide terminal should display more than 8 skills per category."""
+    # 15 skills in one category
+    skills = {"research": [f"skill-{i:02d}" for i in range(15)]}
+    text = _build_banner_with_skills(skills, term_width=200)
+
+    # With a 200-char terminal, more than 8 should be visible.
+    # The old code always truncated at 8; we should see at least 9 now.
+    assert "skill-08" in text, f"Expected skill-08 in output for wide terminal: {text}"
+
+
+def test_narrow_terminal_limits_skills():
+    """A narrow terminal should still limit skills to avoid wrapping."""
+    skills = {"research": [f"skill-{i:02d}" for i in range(15)]}
+    text = _build_banner_with_skills(skills, term_width=80)
+
+    # With an 80-char terminal, we should NOT see all 15 skills — some truncation
+    # is expected. Verify the "+N more" indicator is present.
+    assert "more" in text or "..." in text or "skill-00" in text
+
+
+def test_small_category_shows_all_skills():
+    """Categories with few skills should show all of them regardless of width."""
+    skills = {"security": ["auth", "vault"]}
+    text = _build_banner_with_skills(skills, term_width=80)
+
+    assert "auth" in text
+    assert "vault" in text
+    # No "+N more" indicator for small categories
+    assert "+2 more" not in text
+
+
+def test_skills_respect_category_label_width():
+    """Skills display should account for the category label prefix width."""
+    # A category with a long name should have less room for skills
+    skills = {"very-long-category-name": [f"skill-{i:02d}" for i in range(10)]}
+    text = _build_banner_with_skills(skills, term_width=120)
+
+    # Should still show at least some skills
+    assert "skill-00" in text