From 58f6823e425df013874f79fb5c029a28b93e5c80 Mon Sep 17 00:00:00 2001
From: Sam Bonifacio <sam@bonifacio.name>
Date: Wed, 6 Aug 2025 23:56:12 +1000
Subject: [PATCH] fix(fzf): improve exit code handling with centralized error
 processing

- Extract fzf error handling into reusable _handle_fzf_error() helper
- Distinguish between exit code 1 (no matches) and actual errors
- Return consistent dict structure: {"matches": []} vs {"error": "..."}
- Apply to both multiline and standard filter modes
- Update test to expect empty matches instead of error for no results
---
 mcp_fd_server.py        | 22 ++++++++++++++--------
 tests/test_fd_server.py |  5 +++--
 2 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/mcp_fd_server.py b/mcp_fd_server.py
index 4a192fa..280b849 100755
--- a/mcp_fd_server.py
+++ b/mcp_fd_server.py
@@ -180,6 +180,18 @@ def _suggest_fuzzy_terms(regex_pattern: str) -> str:
     return fuzzy
 
 
+def _handle_fzf_error(exc: subprocess.CalledProcessError, warnings: list[str]) -> dict[str, Any]:
+    """Handle fzf CalledProcessError, returning appropriate result dict."""
+    # fzf returns exit code 1 when no matches found - this is not an error
+    if exc.returncode == 1:
+        return {"matches": []}  # No matches found, return empty list
+
+    error_result: dict[str, Any] = {"error": str(exc)}
+    if warnings:
+        error_result["warnings"] = warnings
+    return error_result
+
+
 # ---------------------------------------------------------------------------
 # FastMCP server instance
 # ---------------------------------------------------------------------------
@@ -355,10 +367,7 @@ def filter_files(
                             matches.append(chunk.decode("utf-8", errors="replace"))
 
         except subprocess.CalledProcessError as exc:
-            error_result: dict[str, Any] = {"error": str(exc)}
-            if warnings:
-                error_result["warnings"] = warnings
-            return error_result
+            return _handle_fzf_error(exc, warnings)
     else:
         # Standard mode - file paths only
         fd_cmd: list[str] = [fd_bin, *shlex.split(fd_flags), pattern, search_path]
@@ -374,10 +383,7 @@ def filter_files(
             fd_proc.wait()
             matches = [_normalize_path(p) for p in out.splitlines() if p]
         except subprocess.CalledProcessError as exc:
-            error_result: dict[str, Any] = {"error": str(exc)}
-            if warnings:
-                error_result["warnings"] = warnings
-            return error_result
+            return _handle_fzf_error(exc, warnings)
 
     if first and matches:
         matches = matches[:1]
diff --git a/tests/test_fd_server.py b/tests/test_fd_server.py
index 76b136b..ddf5d00 100644
--- a/tests/test_fd_server.py
+++ b/tests/test_fd_server.py
@@ -521,8 +521,9 @@ def test_fd_flag_handling(tmp_path: Path):
 
         result = mcp_fd_server.filter_files("nomatch")
 
-        # Should handle empty results gracefully
-        assert "error" in result
+        # Should handle empty results gracefully (fzf exit code 1 = no matches, not error)
+        assert "matches" in result
+        assert result["matches"] == []
 
 
 def test_multiline_support(tmp_path: Path):