feat(display): configurable tool preview length -- show full paths by default (#3841)

Tool call previews (paths, commands, queries) were hardcoded to truncate
at 35-40 chars across CLI spinners, completion lines, and gateway progress
messages. Users could not see full file paths in tool output.

New config option: display.tool_preview_length (default 0 = no limit).
Set a positive number to truncate at that length.

Changes:
- display.py: module-level _tool_preview_max_len with getter/setter;
  build_tool_preview() and get_cute_tool_message() _trunc/_path respect it
- cli.py: reads config at startup, spinner widget respects config
- gateway/run.py: reads config per-message, progress callback respects config
- run_agent.py: removed redundant 30-char quiet-mode spinner truncation
- config.py: added display.tool_preview_length to DEFAULT_CONFIG

Reported by kriskaminski

agent/display.py

@@ -17,6 +17,23 @@ _RESET = "\033[0m"
 
 logger = logging.getLogger(__name__)
 
+# =========================================================================
+# Configurable tool preview length (0 = no limit)
+# Set once at startup by CLI or gateway from display.tool_preview_length config.
+# =========================================================================
+_tool_preview_max_len: int = 0  # 0 = unlimited
+
+
+def set_tool_preview_max_len(n: int) -> None:
+    """Set the global max length for tool call previews. 0 = no limit."""
+    global _tool_preview_max_len
+    _tool_preview_max_len = max(int(n), 0) if n else 0
+
+
+def get_tool_preview_max_len() -> int:
+    """Return the configured max preview length (0 = unlimited)."""
+    return _tool_preview_max_len
+
 
 # =========================================================================
 # Skin-aware helpers (lazy import to avoid circular deps)
@@ -94,8 +111,14 @@ def _oneline(text: str) -> str:
     return " ".join(text.split())
 
 
-def build_tool_preview(tool_name: str, args: dict, max_len: int = 40) -> str | None:
-    """Build a short preview of a tool call's primary argument for display."""
+def build_tool_preview(tool_name: str, args: dict, max_len: int | None = None) -> str | None:
+    """Build a short preview of a tool call's primary argument for display.
+
+    *max_len* controls truncation.  ``None`` (default) defers to the global
+    ``_tool_preview_max_len`` set via config; ``0`` means unlimited.
+    """
+    if max_len is None:
+        max_len = _tool_preview_max_len
     if not args:
         return None
     primary_args = {
@@ -190,7 +213,7 @@ def build_tool_preview(tool_name: str, args: dict, max_len: int = 40) -> str | N
     preview = _oneline(str(value))
     if not preview:
         return None
-    if len(preview) > max_len:
+    if max_len > 0 and len(preview) > max_len:
         preview = preview[:max_len - 3] + "..."
     return preview
 
@@ -484,10 +507,14 @@ def get_cute_tool_message(
 
     def _trunc(s, n=40):
         s = str(s)
+        if _tool_preview_max_len == 0:
+            return s  # no limit
         return (s[:n-3] + "...") if len(s) > n else s
 
     def _path(p, n=35):
         p = str(p)
+        if _tool_preview_max_len == 0:
+            return p  # no limit
         return ("..." + p[-(n-3):]) if len(p) > n else p
 
     def _wrap(line: str) -> str:

cli.py

@@ -449,6 +449,14 @@ try:
 except Exception:
     pass  # Skin engine is optional — default skin used if unavailable
 
+# Initialize tool preview length from config
+try:
+    from agent.display import set_tool_preview_max_len
+    _tpl = CLI_CONFIG.get("display", {}).get("tool_preview_length", 0)
+    set_tool_preview_max_len(int(_tpl) if _tpl else 0)
+except Exception:
+    pass
+
 # Neuter AsyncHttpxClientWrapper.__del__ before any AsyncOpenAI clients are
 # created.  The SDK's __del__ schedules aclose() on asyncio.get_running_loop()
 # which, during CLI idle time, finds prompt_toolkit's event loop and tries to
@@ -4782,8 +4790,10 @@ class HermesCLI:
             from agent.display import get_tool_emoji
             emoji = get_tool_emoji(function_name)
             label = preview or function_name
-            if len(label) > 50:
-                label = label[:47] + "..."
+            from agent.display import get_tool_preview_max_len
+            _pl = get_tool_preview_max_len()
+            if _pl > 0 and len(label) > _pl:
+                label = label[:_pl - 3] + "..."
             self._spinner_text = f"{emoji} {label}"
             self._invalidate()
 

gateway/run.py

@@ -4941,6 +4941,14 @@ class GatewayRunner:
         from hermes_cli.tools_config import _get_platform_tools
         enabled_toolsets = sorted(_get_platform_tools(user_config, platform_key))
 
+        # Apply tool preview length config (0 = no limit)
+        try:
+            from agent.display import set_tool_preview_max_len
+            _tpl = user_config.get("display", {}).get("tool_preview_length", 0)
+            set_tool_preview_max_len(int(_tpl) if _tpl else 0)
+        except Exception:
+            pass
+
         # Tool progress mode from config.yaml: "all", "new", "verbose", "off"
         # Falls back to env vars for backward compatibility.
         # YAML 1.1 parses bare `off` as boolean False — normalise before
@@ -4986,9 +4994,11 @@ class GatewayRunner:
                 return
             
             if preview:
-                # Truncate preview to keep messages clean
-                if len(preview) > 80:
-                    preview = preview[:77] + "..."
+                # Truncate preview unless config says unlimited
+                from agent.display import get_tool_preview_max_len
+                _pl = get_tool_preview_max_len()
+                if _pl > 0 and len(preview) > _pl:
+                    preview = preview[:_pl - 3] + "..."
                 msg = f"{emoji} {tool_name}: \"{preview}\""
             else:
                 msg = f"{emoji} {tool_name}..."

hermes_cli/config.py

@@ -285,6 +285,7 @@ DEFAULT_CONFIG = {
         "show_cost": False,       # Show $ cost in the status bar (off by default)
         "skin": "default",
         "tool_progress_command": False,  # Enable /verbose command in messaging gateway
+        "tool_preview_length": 0,  # Max chars for tool call previews (0 = no limit, show full paths/commands)
     },
 
     # Privacy settings

run_agent.py

@@ -5662,8 +5662,6 @@ class AIAgent:
                     face = random.choice(KawaiiSpinner.KAWAII_WAITING)
                     emoji = _get_tool_emoji(function_name)
                     preview = _build_tool_preview(function_name, function_args) or function_name
-                    if len(preview) > 30:
-                        preview = preview[:27] + "..."
                     spinner = KawaiiSpinner(f"{face} {emoji} {preview}", spinner_type='dots', print_fn=self._print_fn)
                     spinner.start()
                 _spinner_result = None