From c4034e7caf2191d77dcac260446c5451a74b8849 Mon Sep 17 00:00:00 2001
From: T0mSIlver <paraddiz3@gmail.com>
Date: Sat, 27 Jun 2026 00:40:42 +0000
Subject: [PATCH] fix(grep): honor head_limit values above 100
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The head_limit clamp read 'if head_limit < limit and head_limit > 0',
so any value >= 100 was discarded and the cap stayed at 100 — the model
could never raise the limit despite the schema saying it shows all
results. Honor any positive head_limit, document that output is capped
at the first 100 lines when head_limit is omitted, and add a regression
test.
---
 src/fastcontext/agent/tool/grep.py |  7 +++----
 tests/test_tool.py                 | 26 ++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/src/fastcontext/agent/tool/grep.py b/src/fastcontext/agent/tool/grep.py
index 4ee161f..abfa330 100644
--- a/src/fastcontext/agent/tool/grep.py
+++ b/src/fastcontext/agent/tool/grep.py
@@ -55,7 +55,7 @@ class GrepTool(Tool):
             "head_limit": {
                 "type": "number",
                 "minimum": 0,
-                "description": 'Limit output to first N lines/entries, equivalent to "| head -N". Works across all output modes: content (limits output lines), files_with_matches (limits file paths), count (limits count entries). When unspecified, shows all results from ripgrep.',
+                "description": 'Limit output to first N lines/entries, equivalent to "| head -N". Works across all output modes: content (limits output lines), files_with_matches (limits file paths), count (limits count entries). When unspecified, results are capped at the first 100 lines.',
             },
             "multiline": {
                 "type": "boolean",
@@ -104,9 +104,8 @@ async def call(self, parameters: str, **kwargs) -> str:
             return "No matches found"
 
         limit = 100
-        if head_limit is not None:
-            if head_limit < limit and head_limit > 0:
-                limit = head_limit
+        if head_limit is not None and head_limit > 0:
+            limit = head_limit
 
         lines = output.splitlines()
         if len(lines) > limit:
diff --git a/tests/test_tool.py b/tests/test_tool.py
index aa1c311..adc2223 100644
--- a/tests/test_tool.py
+++ b/tests/test_tool.py
@@ -1,11 +1,37 @@
 import asyncio
 import json
+import tempfile
+from pathlib import Path
 
 from fastcontext.agent.tool.glob import GlobTool
 from fastcontext.agent.tool.grep import GrepTool
 from fastcontext.agent.tool.read import ReadTool
 
 
+def test_grep_head_limit():
+    """head_limit must be honored for values above the default 100-line cap,
+    and fall back to 100 when unspecified."""
+    grep = GrepTool()
+    with tempfile.TemporaryDirectory() as cwd:
+        # 250 matching lines, single file, so output exceeds any tested limit.
+        (Path(cwd) / "haystack.txt").write_text("\n".join("MATCH" for _ in range(250)), encoding="utf-8")
+
+        def lines_for(params):
+            out = asyncio.run(grep.call(json.dumps(params), cwd=cwd))
+            return out.splitlines()
+
+        # Above the default cap: previously clamped to 100, must now be honored.
+        # Truncated output = first `limit` lines + one "Results truncated" note.
+        out = lines_for({"pattern": "MATCH", "output_mode": "content", "head_limit": 150})
+        assert len(out) == 151, f"expected 150 lines + note, got {len(out)}"
+        assert "truncated to first 150" in out[-1]
+
+        # Unspecified: 100-line default cap still applies.
+        out = lines_for({"pattern": "MATCH", "output_mode": "content"})
+        assert len(out) == 101, f"expected 100 lines + note, got {len(out)}"
+        assert "truncated to first 100" in out[-1]
+
+
 def test_grep_tool():
     grep = GrepTool()
     params = {