Files
hermes-agent/tests/tools/test_skill_improvements.py
Teknium f6ada27d1c feat(skills): size limits for agent writes + fuzzy matching for patch (#4414)
* feat(skills): add content size limits for agent-created skills

Agent writes via skill_manage (create/edit/patch/write_file) are now
constrained to prevent unbounded growth:

- SKILL.md and supporting files: 100,000 character limit
- Supporting files: additional 1 MiB byte limit
- Patches on oversized hand-placed skills that reduce the size are
  allowed (shrink path), but patches that grow beyond the limit are
  rejected

Hand-placed skills and hub-installed skills have NO hard limit —
they load and function normally regardless of size. Hub installs
get a warning in the log if SKILL.md exceeds 100k chars.

This mirrors the memory system's char_limit pattern. Without this,
the agent auto-grows skills indefinitely through iterative patches
(hermes-agent-dev reached 197k chars / 72k tokens — 40x larger than
the largest skill in the entire skills.sh ecosystem).

Constants: MAX_SKILL_CONTENT_CHARS (100k), MAX_SKILL_FILE_BYTES (1MiB)
Tests: 14 new tests covering all write paths and edge cases

* feat(skills): add fuzzy matching to skill patch

_patch_skill now uses the same 8-strategy fuzzy matching engine
(tools/fuzzy_match.py) as the file patch tool. Handles whitespace
normalization, indentation differences, escape sequences, and
block-anchor matching. Eliminates exact-match failures when agents
patch skills with minor formatting mismatches.
2026-04-01 04:19:19 -07:00

175 lines
5.5 KiB
Python

"""Tests for skill fuzzy patching via tools.fuzzy_match."""
import json
import os
from pathlib import Path
from unittest.mock import patch
import pytest
from tools.skill_manager_tool import (
_create_skill,
_patch_skill,
_write_file,
skill_manage,
)
SKILL_CONTENT = """\
---
name: test-skill
description: A test skill for unit testing.
---
# Test Skill
Step 1: Do the thing.
Step 2: Do another thing.
Step 3: Final step.
"""
# ---------------------------------------------------------------------------
# Fuzzy patching
# ---------------------------------------------------------------------------
class TestFuzzyPatchSkill:
@pytest.fixture(autouse=True)
def setup_skills(self, tmp_path, monkeypatch):
skills_dir = tmp_path / "skills"
skills_dir.mkdir()
monkeypatch.setattr("tools.skill_manager_tool.SKILLS_DIR", skills_dir)
monkeypatch.setenv("HERMES_HOME", str(tmp_path))
self.skills_dir = skills_dir
def test_exact_match_still_works(self):
_create_skill("test-skill", SKILL_CONTENT)
result = _patch_skill("test-skill", "Step 1: Do the thing.", "Step 1: Done!")
assert result["success"] is True
content = (self.skills_dir / "test-skill" / "SKILL.md").read_text()
assert "Step 1: Done!" in content
def test_whitespace_trimmed_match(self):
"""Patch with extra leading whitespace should still find the target."""
skill = """\
---
name: ws-skill
description: Whitespace test
---
# Commands
def hello():
print("hi")
"""
_create_skill("ws-skill", skill)
# Agent sends patch with no leading whitespace (common LLM behaviour)
result = _patch_skill("ws-skill", "def hello():\n print(\"hi\")", "def hello():\n print(\"hello world\")")
assert result["success"] is True
content = (self.skills_dir / "ws-skill" / "SKILL.md").read_text()
assert 'print("hello world")' in content
def test_indentation_flexible_match(self):
"""Patch where only indentation differs should succeed."""
skill = """\
---
name: indent-skill
description: Indentation test
---
# Steps
1. First step
2. Second step
3. Third step
"""
_create_skill("indent-skill", skill)
# Agent sends with different indentation
result = _patch_skill(
"indent-skill",
"1. First step\n2. Second step",
"1. Updated first\n2. Updated second"
)
assert result["success"] is True
content = (self.skills_dir / "indent-skill" / "SKILL.md").read_text()
assert "Updated first" in content
def test_multiple_matches_blocked_without_replace_all(self):
"""Multiple fuzzy matches should return an error without replace_all."""
skill = """\
---
name: dup-skill
description: Duplicate test
---
# Steps
word word word
"""
_create_skill("dup-skill", skill)
result = _patch_skill("dup-skill", "word", "replaced")
assert result["success"] is False
assert "match" in result["error"].lower()
def test_replace_all_with_fuzzy(self):
skill = """\
---
name: dup-skill
description: Duplicate test
---
# Steps
word word word
"""
_create_skill("dup-skill", skill)
result = _patch_skill("dup-skill", "word", "replaced", replace_all=True)
assert result["success"] is True
content = (self.skills_dir / "dup-skill" / "SKILL.md").read_text()
assert "word" not in content
assert "replaced" in content
def test_no_match_returns_preview(self):
_create_skill("test-skill", SKILL_CONTENT)
result = _patch_skill("test-skill", "this does not exist anywhere", "replacement")
assert result["success"] is False
assert "file_preview" in result
def test_fuzzy_patch_on_supporting_file(self):
"""Fuzzy matching should also work on supporting files."""
_create_skill("test-skill", SKILL_CONTENT)
ref_content = " function hello() {\n console.log('hi');\n }"
_write_file("test-skill", "references/code.js", ref_content)
# Patch with stripped indentation
result = _patch_skill(
"test-skill",
"function hello() {\nconsole.log('hi');\n}",
"function hello() {\nconsole.log('hello world');\n}",
file_path="references/code.js"
)
assert result["success"] is True
content = (self.skills_dir / "test-skill" / "references" / "code.js").read_text()
assert "hello world" in content
def test_patch_preserves_frontmatter_validation(self):
"""Fuzzy matching should still run frontmatter validation on SKILL.md."""
_create_skill("test-skill", SKILL_CONTENT)
# Try to destroy the frontmatter via patch
result = _patch_skill("test-skill", "---\nname: test-skill", "BROKEN")
assert result["success"] is False
assert "structure" in result["error"].lower() or "frontmatter" in result["error"].lower()
def test_skill_manage_patch_uses_fuzzy(self):
"""The dispatcher should route to the fuzzy-matching patch."""
_create_skill("test-skill", SKILL_CONTENT)
raw = skill_manage(
action="patch",
name="test-skill",
old_string=" Step 1: Do the thing.", # extra leading space
new_string="Step 1: Updated.",
)
result = json.loads(raw)
# Should succeed via line-trimmed or indentation-flexible matching
assert result["success"] is True