From 72a3915e8158ddace778b1eac03b11612954d21a Mon Sep 17 00:00:00 2001
From: Matt McKay <mmcky@users.noreply.github.com>
Date: Mon, 25 May 2026 15:45:55 +1000
Subject: [PATCH 1/2] refactor: consolidate VALID_CATEGORIES; delete dead
 prompt_loader
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Addresses §4.1 + §4.2 of TECHNICAL-REVIEW.md.

Before: the 8-category list was defined in four places that could drift
silently — `cli.ALL_CATEGORIES` (list), `GitHubHandler.VALID_CATEGORIES`
(set), `PromptLoader.VALID_CATEGORIES` (list), and the keys of
`reviewer.RULE_EVALUATION_ORDER` (dict). Plus a duplicate hardcoded list
inside `review_lecture_smart`. Test coverage only verified that two of
those four matched.

After: one tuple in the new `style_checker/categories.py` module that
every other call site imports. RULE_EVALUATION_ORDER still owns the
per-category rule ordering, but a new test asserts its keys are exactly
`VALID_CATEGORIES` in the same order — drift fails CI loudly.

prompt_loader.py was dead production code: only tests imported the
PromptLoader class. The runtime (`reviewer.create_single_rule_prompt`)
loads prompts directly. Deleting the module + its test removes the
fourth source-of-truth for the category list and ~230 lines of
unmaintained code, with no behavior change.

Files touched:
  + style_checker/categories.py        (new, 22 lines — the single source)
  - style_checker/prompt_loader.py     (deleted, was ~230 lines, unused at runtime)
  - tests/test_prompt_loader.py        (deleted, tested the deleted class)
  M style_checker/cli.py               (import VALID_CATEGORIES; drop ALL_CATEGORIES alias)
  M style_checker/github_handler.py    (drop class-attr; import VALID_CATEGORIES)
  M style_checker/reviewer.py          (drop hardcoded list in review_lecture_smart)
  M tests/test_cli.py                  (import VALID_CATEGORIES from canonical location)
  M tests/test_parsing.py              (drop fixture's class-attr setup)
  M tests/test_reviewer.py             (import from categories; add drift-detection test)

Test suite: 85 passed (was 91; net -6 from prompt_loader test deletion
+ 1 new RULE_EVALUATION_ORDER consistency test).
---
 style_checker/categories.py     |  21 +++
 style_checker/cli.py            |  14 +-
 style_checker/github_handler.py |  12 +-
 style_checker/prompt_loader.py  | 231 --------------------------------
 style_checker/reviewer.py       |  18 +--
 tests/test_cli.py               |   9 +-
 tests/test_parsing.py           |  11 +-
 tests/test_prompt_loader.py     |  77 -----------
 tests/test_reviewer.py          |  33 +++--
 9 files changed, 66 insertions(+), 360 deletions(-)
 create mode 100644 style_checker/categories.py
 delete mode 100644 style_checker/prompt_loader.py
 delete mode 100644 tests/test_prompt_loader.py

diff --git a/style_checker/categories.py b/style_checker/categories.py
new file mode 100644
index 0000000..dceefab
--- /dev/null
+++ b/style_checker/categories.py
@@ -0,0 +1,21 @@
+"""
+Single source of truth for the style-rule category names.
+
+Every category here must have a corresponding `{name}-rules.md` file in
+`style_checker/rules/` and a matching entry in
+`reviewer.RULE_EVALUATION_ORDER`. The consistency between this tuple and
+`RULE_EVALUATION_ORDER.keys()` is enforced by a test in `tests/test_reviewer.py`.
+"""
+
+# Ordered — index is the default category processing order used by
+# `StyleReviewer.review_lecture_smart`.
+VALID_CATEGORIES = (
+    "writing",
+    "math",
+    "code",
+    "jax",
+    "figures",
+    "references",
+    "links",
+    "admonitions",
+)
diff --git a/style_checker/cli.py b/style_checker/cli.py
index 8ccb4a7..b6c07f0 100644
--- a/style_checker/cli.py
+++ b/style_checker/cli.py
@@ -22,16 +22,10 @@
 from datetime import datetime
 
 from style_checker import __version__
+from style_checker.categories import VALID_CATEGORIES
 from style_checker.reviewer import StyleReviewer
 
 
-# All available categories (matches reviewer.RULE_EVALUATION_ORDER keys)
-ALL_CATEGORIES = [
-    "writing", "math", "code", "jax",
-    "figures", "references", "links", "admonitions",
-]
-
-
 def display_width(s: str) -> int:
     """Calculate terminal display width, accounting for wide/emoji characters."""
     w = 0
@@ -278,13 +272,13 @@ def main():
     # Parse categories
     if args.categories:
         categories = [c.strip() for c in args.categories.split(",")]
-        invalid = [c for c in categories if c not in ALL_CATEGORIES]
+        invalid = [c for c in categories if c not in VALID_CATEGORIES]
         if invalid:
             print(f"Error: invalid categories: {', '.join(invalid)}", file=sys.stderr)
-            print(f"Valid categories: {', '.join(ALL_CATEGORIES)}", file=sys.stderr)
+            print(f"Valid categories: {', '.join(VALID_CATEGORIES)}", file=sys.stderr)
             sys.exit(1)
     else:
-        categories = list(ALL_CATEGORIES)
+        categories = list(VALID_CATEGORIES)
 
     # API key
     api_key = args.api_key or os.environ.get("ANTHROPIC_API_KEY")
diff --git a/style_checker/github_handler.py b/style_checker/github_handler.py
index 3281c42..47af966 100644
--- a/style_checker/github_handler.py
+++ b/style_checker/github_handler.py
@@ -11,16 +11,12 @@
 from github import Github, GithubException
 from datetime import datetime
 
+from .categories import VALID_CATEGORIES
+
 
 class GitHubHandler:
     """Handles GitHub API interactions for PR and issue management"""
 
-    # Valid category names (must match files in style_checker/rules/)
-    VALID_CATEGORIES = {
-        'writing', 'math', 'code', 'jax',
-        'figures', 'references', 'links', 'admonitions'
-    }
-
     def __init__(self, token: str, repository: str):
         """
         Initialize GitHub handler
@@ -79,10 +75,10 @@ def extract_lecture_from_comment(self, comment_body: str) -> Optional[Tuple[str,
                     
                     # Validate categories
                     if categories != ['all']:
-                        invalid = [c for c in categories if c not in self.VALID_CATEGORIES]
+                        invalid = [c for c in categories if c not in VALID_CATEGORIES]
                         if invalid:
                             print(f"⚠️  Invalid categories: {', '.join(invalid)}")
-                            print(f"   Valid categories: {', '.join(sorted(self.VALID_CATEGORIES))}")
+                            print(f"   Valid categories: {', '.join(sorted(VALID_CATEGORIES))}")
                             return None
                 else:
                     categories = ['all']  # Default to all categories
diff --git a/style_checker/prompt_loader.py b/style_checker/prompt_loader.py
deleted file mode 100644
index 0414abf..0000000
--- a/style_checker/prompt_loader.py
+++ /dev/null
@@ -1,231 +0,0 @@
-"""
-Simple utility to load markdown prompt templates by category.
-
-Loads concise instruction prompts from prompts/ and detailed rules from rules/,
-then combines them for the LLM.
-"""
-
-from pathlib import Path
-import re
-from typing import List, Optional
-
-
-class PromptLoader:
-    """Loads category-specific style guide prompts and rules from markdown files."""
-    
-    VALID_CATEGORIES = [
-        "writing", "math", "code", "jax",
-        "figures", "references", "links", "admonitions"
-    ]
-    
-    def __init__(self, prompts_dir: Optional[Path] = None, rules_dir: Optional[Path] = None):
-        """
-        Initialize the prompt loader.
-        
-        Args:
-            prompts_dir: Directory containing prompt markdown files.
-                        Defaults to style_checker/prompts/
-            rules_dir: Directory containing rule markdown files.
-                      Defaults to style_checker/rules/
-        """
-        if prompts_dir is None:
-            prompts_dir = Path(__file__).parent / "prompts"
-        if rules_dir is None:
-            rules_dir = Path(__file__).parent / "rules"
-        
-        self.prompts_dir = Path(prompts_dir)
-        self.rules_dir = Path(rules_dir)
-        
-        if not self.prompts_dir.exists():
-            raise FileNotFoundError(
-                f"Prompts directory not found: {self.prompts_dir}"
-            )
-        if not self.rules_dir.exists():
-            raise FileNotFoundError(
-                f"Rules directory not found: {self.rules_dir}"
-            )
-    
-    def load_prompt(self, categories: List[str], lecture_content: str) -> str:
-        """
-        Load and combine prompts + rules for specified categories.
-        
-        Approach:
-        1. Load concise instruction prompt
-        2. Load detailed rules
-        3. Combine: prompt + rules + lecture_content
-        
-        Args:
-            categories: List of category names (e.g., ["writing", "math"])
-            lecture_content: The lecture markdown content to review
-        
-        Returns:
-            Complete prompt with instructions, rules, and lecture content
-        
-        Raises:
-            ValueError: If invalid category specified
-            FileNotFoundError: If prompt or rules file not found
-        """
-        # Validate categories
-        invalid = [c for c in categories if c not in self.VALID_CATEGORIES]
-        if invalid:
-            raise ValueError(
-                f"Invalid categories: {invalid}. "
-                f"Valid options: {self.VALID_CATEGORIES}"
-            )
-        
-        # For single category, use simple combination
-        if len(categories) == 1:
-            return self._load_single_category(categories[0], lecture_content)
-        
-        # For multiple categories, combine them
-        return self._combine_categories(categories, lecture_content)
-    
-    def _load_single_category(self, category: str, lecture_content: str) -> str:
-        """
-        Load prompt and rules for a single category.
-        
-        - prompt file: category-prompt.md
-        - rules file: category-rules.md
-        """
-        # Load prompt (instruction template)
-        prompt_file = self.prompts_dir / f"{category}-prompt.md"
-        if not prompt_file.exists():
-            raise FileNotFoundError(f"Prompt file not found: {prompt_file}")
-        
-        with open(prompt_file, 'r') as f:
-            prompt = f.read()
-        
-        # Debug: Check prompt version
-        if category == "writing":
-            # Check for version comment
-            version_match = re.search(r'<!-- Prompt Version: ([\d.]+)', prompt)
-            if version_match:
-                version = version_match.group(1)
-                print(f"    ✓ Using writing prompt v{version}")
-            elif "SEQUENTIAL RULE EVALUATION" in prompt:
-                print("    ✓ Using UPDATED writing prompt (SEQUENTIAL RULE EVALUATION)")
-            else:
-                print("    ⚠️  Using OLD writing prompt (missing SEQUENTIAL RULE EVALUATION)")
-        
-        # Load rules (detailed specifications)
-        rules_file = self.rules_dir / f"{category}-rules.md"
-        if not rules_file.exists():
-            raise FileNotFoundError(f"Rules file not found: {rules_file}")
-        
-        with open(rules_file, 'r') as f:
-            rules = f.read()
-        
-        # Combine: prompt + rules + lecture
-        full_prompt = f"""{prompt}
-
-## Style Guide Database
-
-{rules}
-
-## Lecture to Review
-
-{lecture_content}
-"""
-        return full_prompt
-    
-    def _combine_categories(self, categories: List[str], lecture_content: str) -> str:
-        """
-        Combine multiple category prompts and rules into one.
-        
-        Creates a unified prompt that checks multiple categories while keeping
-        the structure similar to single-category reviews.
-        """
-        cat_list = ", ".join(categories)
-        
-        # Start with a combined header
-        combined_prompt = f"""# QuantEcon Multi-Category Style Checker
-
-You are an expert technical writing editor specializing in QuantEcon lecture materials. 
-
-Your task is to review a lecture document for violations in these categories: **{cat_list}**
-
-## Instructions
-
-1. **Focus on the specified categories only**: {cat_list}
-
-2. **Read the entire lecture carefully** to understand the context.
-
-3. **Check systematically** against all rules in the categories below.
-
-4. **For each violation found**, provide:
-   - **Rule Code and Title**: e.g., `qe-writing-001: One sentence per paragraph`
-   - **Location**: Line number or section where the violation occurs
-   - **Current**: Quote the problematic text exactly
-   - **Issue**: Brief explanation of why this violates the rule
-   - **Suggested Fix**: Specific corrected version
-
-5. **Prioritize actionable feedback**:
-   - Focus on `rule` category violations first (clearly actionable)
-   - Include `style` category suggestions when they significantly impact quality
-   - For style suggestions, explain your reasoning clearly
-
-6. **Group by category** in your output for clarity
-
-## Output Format
-
-Provide a comprehensive review with violations grouped by category:
-
-```markdown
-# Style Review for [filename]
-
-## Summary
-- Total violations: [number]
-- By category: Writing([n]), Math([n]), Code([n]), etc.
-
-## Violations by Category
-
-### Writing Issues
-[violations...]
-
-### Math Issues
-[violations...]
-
-[etc for each category checked...]
-
-## Overall Assessment
-[Brief summary]
-```
-
----
-
-"""
-        
-        # Load and append each category's rules
-        for category in categories:
-            rules_file = self.rules_dir / f"{category}-rules.md"
-            
-            if not rules_file.exists():
-                continue
-            
-            with open(rules_file, 'r') as f:
-                rules = f.read()
-            
-            combined_prompt += f"## {category.title()} Rules\n\n{rules}\n\n---\n\n"
-        
-        # Add lecture content
-        combined_prompt += f"""## Lecture to Review
-
-{lecture_content}
-"""
-        
-        return combined_prompt
-
-
-def load_prompt(categories: List[str], lecture_content: str) -> str:
-    """
-    Convenience function to load prompts.
-    
-    Args:
-        categories: List of category names (e.g., ["writing", "math"])
-        lecture_content: The lecture markdown content to review
-    
-    Returns:
-        Complete prompt ready for LLM
-    """
-    loader = PromptLoader()
-    return loader.load_prompt(categories, lecture_content)
diff --git a/style_checker/reviewer.py b/style_checker/reviewer.py
index 444af28..6a41874 100644
--- a/style_checker/reviewer.py
+++ b/style_checker/reviewer.py
@@ -13,6 +13,7 @@
 
 import anthropic
 
+from .categories import VALID_CATEGORIES
 from .fix_applier import apply_fixes, validate_fix_quality
 
 
@@ -575,24 +576,15 @@ def review_lecture_smart(
         Returns:
             Dictionary with all violations found across all categories
         """
-        # Define all categories to check (matches files in style_checker/rules/)
-        all_categories = [
-            'writing',
-            'math',
-            'code',
-            'jax',
-            'figures',
-            'references',
-            'links',
-            'admonitions'
-        ]
-        
+        # Single source of truth for the category list lives in categories.py.
+        all_categories = list(VALID_CATEGORIES)
+
         print(f"\n🤖 Starting AI-powered review using single-rule evaluation...")
         print(f"📊 Lecture: {lecture_name}")
         print(f"\n📦 Processing {len(all_categories)} categories:")
         for category in all_categories:
             print(f"   • {category}")
-        
+
         # Delegate to review_lecture_single_rule which handles:
         # - Single-rule-per-LLM-call evaluation
         # - Sequential fix application between rules
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 096bfd7..5bb216f 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -15,7 +15,8 @@
 import tempfile
 from pathlib import Path
 
-from style_checker.cli import format_report, default_report_path, check_git_dirty, ALL_CATEGORIES
+from style_checker.cli import format_report, default_report_path, check_git_dirty
+from style_checker.categories import VALID_CATEGORIES
 from style_checker import __version__
 
 
@@ -244,12 +245,12 @@ class TestCategories:
     """Tests for category validation."""
 
     def test_all_categories_present(self):
-        """ALL_CATEGORIES should match the 8 standard categories."""
+        """VALID_CATEGORIES should match the 8 standard categories."""
         expected = {'writing', 'math', 'code', 'jax', 'figures', 'references', 'links', 'admonitions'}
-        assert set(ALL_CATEGORIES) == expected
+        assert set(VALID_CATEGORIES) == expected
 
     def test_all_categories_count(self):
-        assert len(ALL_CATEGORIES) == 8
+        assert len(VALID_CATEGORIES) == 8
 
 
 # ---------------------------------------------------------------------------
diff --git a/tests/test_parsing.py b/tests/test_parsing.py
index fbb1d17..25ca07b 100644
--- a/tests/test_parsing.py
+++ b/tests/test_parsing.py
@@ -13,12 +13,13 @@
 
 @pytest.fixture
 def handler():
-    """Create a GitHubHandler without connecting to GitHub."""
+    """Create a GitHubHandler without connecting to GitHub.
+
+    The method under test reads VALID_CATEGORIES from the module-level
+    `style_checker.categories` import, so no class-attribute setup needed.
+    """
     with patch.object(GitHubHandler, '__init__', lambda self, *a, **kw: None):
-        h = GitHubHandler.__new__(GitHubHandler)
-        # Set the class attribute that extract_lecture_from_comment uses
-        h.VALID_CATEGORIES = GitHubHandler.VALID_CATEGORIES
-        return h
+        return GitHubHandler.__new__(GitHubHandler)
 
 
 class TestCommentParsing:
diff --git a/tests/test_prompt_loader.py b/tests/test_prompt_loader.py
deleted file mode 100644
index a8e5b83..0000000
--- a/tests/test_prompt_loader.py
+++ /dev/null
@@ -1,77 +0,0 @@
-"""
-Tests for prompt_loader.py — PromptLoader class
-"""
-
-import pytest
-from style_checker.prompt_loader import PromptLoader, load_prompt
-
-
-@pytest.fixture
-def loader():
-    """Create a PromptLoader using the real prompts/rules directories."""
-    return PromptLoader()
-
-
-class TestPromptLoader:
-    """Test PromptLoader class"""
-
-    def test_load_single_category(self, loader):
-        """Loading a single category should return prompt + rules + lecture"""
-        result = loader.load_prompt(["writing"], "# Test Lecture\n\nSome content.")
-        assert "# Test Lecture" in result
-        assert "Some content." in result
-        # Should include rules content
-        assert "qe-writing-001" in result
-
-    def test_load_multiple_categories(self, loader):
-        """Loading multiple categories should include rules from all"""
-        result = loader.load_prompt(["writing", "math"], "# Test\n\nContent.")
-        assert "qe-writing-001" in result
-        assert "qe-math-001" in result
-
-    def test_all_categories_loadable(self, loader):
-        """Every valid category should load without error"""
-        for category in PromptLoader.VALID_CATEGORIES:
-            result = loader.load_prompt([category], "# Test\n\nContent.")
-            assert len(result) > 100, f"Category '{category}' returned suspiciously short prompt"
-
-    def test_invalid_category_raises(self, loader):
-        """Invalid category name should raise ValueError"""
-        with pytest.raises(ValueError, match="Invalid categories"):
-            loader.load_prompt(["nonexistent"], "# Test")
-
-    def test_prompt_includes_lecture_content(self, loader):
-        """Lecture content should appear in the final prompt"""
-        marker = "UNIQUE_MARKER_12345"
-        result = loader.load_prompt(["writing"], f"# Test\n\n{marker}")
-        assert marker in result
-
-    def test_prompt_file_has_version(self, loader):
-        """All prompt files should have version comments"""
-        for category in PromptLoader.VALID_CATEGORIES:
-            prompt_file = loader.prompts_dir / f"{category}-prompt.md"
-            content = prompt_file.read_text()
-            assert "Prompt Version:" in content, \
-                f"{category}-prompt.md missing version comment"
-
-    def test_rules_file_has_rules(self, loader):
-        """All rules files should contain at least one rule"""
-        for category in PromptLoader.VALID_CATEGORIES:
-            rules_file = loader.rules_dir / f"{category}-rules.md"
-            content = rules_file.read_text()
-            assert "### Rule:" in content, \
-                f"{category}-rules.md has no rules"
-
-
-class TestConvenienceFunction:
-    """Test the load_prompt() convenience function"""
-
-    def test_load_prompt_function(self):
-        """Convenience function should work identically to class method"""
-        result = load_prompt(["math"], "# Test\n\nContent.")
-        assert "qe-math-001" in result
-
-    def test_load_prompt_invalid_category(self):
-        """Convenience function should raise on invalid category"""
-        with pytest.raises(ValueError):
-            load_prompt(["invalid"], "# Test")
diff --git a/tests/test_reviewer.py b/tests/test_reviewer.py
index b33368d..708e86d 100644
--- a/tests/test_reviewer.py
+++ b/tests/test_reviewer.py
@@ -2,11 +2,11 @@
 Tests for reviewer.py — extract_individual_rules() and RULE_EVALUATION_ORDER
 """
 
+from style_checker.categories import VALID_CATEGORIES
 from style_checker.reviewer import (
     extract_individual_rules,
     RULE_EVALUATION_ORDER,
 )
-from style_checker.prompt_loader import PromptLoader
 
 
 # Expected rule counts per category (from rule files)
@@ -27,7 +27,7 @@ class TestExtractIndividualRules:
 
     def test_all_categories_extract(self):
         """Every category should extract at least one rule"""
-        for category in PromptLoader.VALID_CATEGORIES:
+        for category in VALID_CATEGORIES:
             rules = extract_individual_rules(category)
             assert len(rules) > 0, f"No rules extracted for '{category}'"
 
@@ -42,7 +42,7 @@ def test_total_rule_count(self):
         """Total rules across all categories should be 49"""
         total = sum(
             len(extract_individual_rules(cat))
-            for cat in PromptLoader.VALID_CATEGORIES
+            for cat in VALID_CATEGORIES
         )
         assert total == 49
 
@@ -57,7 +57,7 @@ def test_rule_has_required_fields(self):
 
     def test_rule_type_values(self):
         """Rule types should only be 'rule', 'style', or 'migrate'"""
-        for category in PromptLoader.VALID_CATEGORIES:
+        for category in VALID_CATEGORIES:
             rules = extract_individual_rules(category)
             for rule in rules:
                 assert rule['rule_type'] in ('rule', 'style', 'migrate'), \
@@ -65,7 +65,7 @@ def test_rule_type_values(self):
 
     def test_rule_id_format(self):
         """Rule IDs should follow qe-category-NNN pattern"""
-        for category in PromptLoader.VALID_CATEGORIES:
+        for category in VALID_CATEGORIES:
             rules = extract_individual_rules(category)
             for rule in rules:
                 assert rule['rule_id'].startswith('qe-'), \
@@ -74,7 +74,7 @@ def test_rule_id_format(self):
     def test_no_duplicate_rule_ids(self):
         """No duplicate rule IDs across all categories"""
         all_ids = []
-        for category in PromptLoader.VALID_CATEGORIES:
+        for category in VALID_CATEGORIES:
             rules = extract_individual_rules(category)
             all_ids.extend(r['rule_id'] for r in rules)
         assert len(all_ids) == len(set(all_ids)), \
@@ -88,15 +88,24 @@ def test_nonexistent_category_returns_empty(self):
 class TestRuleEvaluationOrder:
     """Test RULE_EVALUATION_ORDER configuration"""
 
+    def test_rule_evaluation_order_keys_match_valid_categories(self):
+        """RULE_EVALUATION_ORDER must have exactly the same keys as VALID_CATEGORIES,
+        in the same order. Catches drift between the two when either is edited."""
+        assert tuple(RULE_EVALUATION_ORDER.keys()) == tuple(VALID_CATEGORIES), (
+            "RULE_EVALUATION_ORDER keys diverged from VALID_CATEGORIES.\n"
+            f"  RULE_EVALUATION_ORDER: {tuple(RULE_EVALUATION_ORDER.keys())}\n"
+            f"  VALID_CATEGORIES:      {tuple(VALID_CATEGORIES)}"
+        )
+
     def test_all_categories_have_order(self):
         """Every valid category should have an evaluation order defined"""
-        for category in PromptLoader.VALID_CATEGORIES:
+        for category in VALID_CATEGORIES:
             assert category in RULE_EVALUATION_ORDER, \
                 f"'{category}' missing from RULE_EVALUATION_ORDER"
 
     def test_order_matches_extracted_rules(self):
         """Evaluation order should include exactly the rules in the rule files"""
-        for category in PromptLoader.VALID_CATEGORIES:
+        for category in VALID_CATEGORIES:
             rules = extract_individual_rules(category)
             extracted_ids = [r['rule_id'] for r in rules]
             ordered_ids = RULE_EVALUATION_ORDER[category]
@@ -106,7 +115,7 @@ def test_order_matches_extracted_rules(self):
 
     def test_evaluation_order_is_respected(self):
         """extract_individual_rules should return rules in RULE_EVALUATION_ORDER"""
-        for category in PromptLoader.VALID_CATEGORIES:
+        for category in VALID_CATEGORIES:
             rules = extract_individual_rules(category)
             ids = [r['rule_id'] for r in rules]
             expected = RULE_EVALUATION_ORDER[category]
@@ -131,7 +140,7 @@ class TestRuleTypeCounts:
     def test_rule_type_count(self):
         """Should have 32 'rule' type rules"""
         count = sum(
-            1 for cat in PromptLoader.VALID_CATEGORIES
+            1 for cat in VALID_CATEGORIES
             for r in extract_individual_rules(cat)
             if r['rule_type'] == 'rule'
         )
@@ -140,7 +149,7 @@ def test_rule_type_count(self):
     def test_style_type_count(self):
         """Should have 13 'style' type rules"""
         count = sum(
-            1 for cat in PromptLoader.VALID_CATEGORIES
+            1 for cat in VALID_CATEGORIES
             for r in extract_individual_rules(cat)
             if r['rule_type'] == 'style'
         )
@@ -149,7 +158,7 @@ def test_style_type_count(self):
     def test_migrate_type_count(self):
         """Should have 4 'migrate' type rules"""
         count = sum(
-            1 for cat in PromptLoader.VALID_CATEGORIES
+            1 for cat in VALID_CATEGORIES
             for r in extract_individual_rules(cat)
             if r['rule_type'] == 'migrate'
         )

From 01c50cf849490783deb2b6344a068421c86c054d Mon Sep 17 00:00:00 2001
From: Matt McKay <mmcky@users.noreply.github.com>
Date: Mon, 25 May 2026 17:01:14 +1000
Subject: [PATCH 2/2] =?UTF-8?q?refactor:=20consolidate=208=20byte-identica?=
 =?UTF-8?q?l=20prompts=20into=20single=20prompt.md=20(=C2=A71.4)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Addresses Copilot review feedback on PR #17 by removing the root cause
rather than documenting it: the prompt-file-per-category invariant.

Before: 8 byte-identical files (admonitions-prompt.md, code-prompt.md,
...) sat in style_checker/prompts/. create_single_rule_prompt picked
one based on the category arg, even though the content was the same
for every category. The TECHNICAL-REVIEW §1.4 and roadmap §4.6 both
flagged this — Copilot's two comments on PR #17 surfaced the cost
(docstring drift risk + lost test coverage when prompt_loader was
deleted).

After: a single style_checker/prompts/prompt.md is loaded once per
rule invocation, identical for every category. The `category` arg on
create_single_rule_prompt is now unused but kept in the signature so
callers don't need to change if a category-specific prompt is ever
reintroduced.

Replacement test coverage in test_reviewer.py:
- test_prompt_file_exists — catches packaging regressions where the
  prompt file isn't shipped.
- test_prompt_file_has_version_header — keeps the version-tracking
  invariant that test_prompt_loader used to enforce.

Docs updated:
- architecture.md: diagram, "Prompt Construction" section, repo tree.
- extended-thinking.md: "8 identical (for now)" → "single shared".
- testing.md: drop test_prompt_loader.py reference; refresh coverage.
- roadmap.md: mark §4.6 (prompt consolidation) as Done (PR #17).
- contributing.md: update "Adding a New Category" steps (no more
  category-prompt.md to create; mention categories.py and the test
  that catches RULE_EVALUATION_ORDER drift).
- tests/README.md: same content updates + uv install command.

Net: -7 files (deleted 8 .md, added 1 .md), reviewer.py simpler,
docs aligned with current architecture.
---
 docs/developer/architecture.md                | 42 +++++++++++--------
 docs/developer/contributing.md                | 11 +++--
 docs/developer/extended-thinking.md           |  2 +-
 docs/developer/roadmap.md                     |  4 +-
 docs/developer/testing.md                     | 17 ++++----
 style_checker/prompts/code-prompt.md          | 41 ------------------
 style_checker/prompts/figures-prompt.md       | 41 ------------------
 style_checker/prompts/jax-prompt.md           | 41 ------------------
 style_checker/prompts/links-prompt.md         | 41 ------------------
 style_checker/prompts/math-prompt.md          | 41 ------------------
 .../{admonitions-prompt.md => prompt.md}      |  0
 style_checker/prompts/references-prompt.md    | 41 ------------------
 style_checker/prompts/writing-prompt.md       | 41 ------------------
 style_checker/reviewer.py                     | 25 ++++++-----
 tests/README.md                               | 16 +++----
 tests/test_reviewer.py                        | 29 +++++++++++++
 16 files changed, 87 insertions(+), 346 deletions(-)
 delete mode 100644 style_checker/prompts/code-prompt.md
 delete mode 100644 style_checker/prompts/figures-prompt.md
 delete mode 100644 style_checker/prompts/jax-prompt.md
 delete mode 100644 style_checker/prompts/links-prompt.md
 delete mode 100644 style_checker/prompts/math-prompt.md
 rename style_checker/prompts/{admonitions-prompt.md => prompt.md} (100%)
 delete mode 100644 style_checker/prompts/references-prompt.md
 delete mode 100644 style_checker/prompts/writing-prompt.md

diff --git a/docs/developer/architecture.md b/docs/developer/architecture.md
index a26de46..9bd9df0 100644
--- a/docs/developer/architecture.md
+++ b/docs/developer/architecture.md
@@ -17,7 +17,7 @@ Technical documentation for developers working on the QuantEcon Style Guide Chec
                            ▼
 ┌─────────────────────────────────────────────────────┐
 │                      action.yml                      │
-│  Sets up Python, installs deps, invokes action.py    │
+│  Installs uv, syncs deps, invokes action.py via uv   │
 └──────────────────────────┬──────────────────────────┘
                            │
               ┌────────────┴────────────┐
@@ -32,18 +32,16 @@ Technical documentation for developers working on the QuantEcon Style Guide Chec
                     ┌───────────────────┼──────────────┐
                     ▼                   ▼              ▼
           ┌──────────────┐   ┌──────────────┐  ┌─────────────┐
-          │prompt_loader  │   │ fix_applier   │  │Anthropic API│
-          │Load prompts   │   │Apply fixes    │  │(Claude)     │
-          │Load rules     │   │Validate       │  └─────────────┘
-          └──────┬───────┘   └──────────────┘
-          ┌──────┴───────┐
-          ▼              ▼
-    ┌──────────┐  ┌──────────┐
-    │prompts/  │  │ rules/   │
-    │(8 files) │  │(8 files) │
-    └──────────┘  └──────────┘
+          │ prompts/      │   │ fix_applier   │  │Anthropic API│
+          │ prompt.md     │   │Apply fixes    │  │(Claude)     │
+          │  + rules/*.md │   │Validate       │  └─────────────┘
+          └──────────────┘   └──────────────┘
 ```
 
+`categories.py` is the single source of truth for the 8 category names
+(`writing`, `math`, `code`, `jax`, `figures`, `references`, `links`,
+`admonitions`); every other module imports `VALID_CATEGORIES` from it.
+
 ## Two Entry Points, One Engine
 
 - **`action.py`**: GitHub Action entry point. Reads files via GitHub API, creates PRs with fixes.
@@ -87,15 +85,21 @@ Key classes:
 - `AnthropicProvider` — Claude API wrapper with extended thinking and streaming fallback
 - `StyleReviewer` — Main review orchestrator
 
-### Prompt Loader (`prompt_loader.py`)
+### Prompt Construction (`reviewer.create_single_rule_prompt`)
 
-Loads and combines category-specific prompts and rules:
+For each rule, the reviewer builds an LLM prompt as:
 
 ```
-[Category Prompt]  +  [Style Guide Rules]  +  [Lecture Content]  →  LLM
+[Shared base prompt (prompts/prompt.md)]
+  + [Single rule definition from rules/{category}-rules.md]
+  + [Lecture content]
+  → LLM
 ```
 
-The prompt is rule-agnostic — all 8 category prompts are identical. Scope and analysis context come from the rule definitions themselves. This prevents signal dilution from category-specific instructions.
+The base prompt is rule-agnostic — a single `prompts/prompt.md` file is
+shared across all 8 categories. Scope and analysis context come from the
+rule definitions themselves, which prevents signal dilution from
+category-specific instructions.
 
 ### Fix Applier (`fix_applier.py`)
 
@@ -228,16 +232,18 @@ Depends on lecture length and violations found.
 ```
 action-style-guide/
 ├── action.yml                 # GitHub Action definition
+├── pyproject.toml             # Package + dep manifest (uv-managed)
+├── uv.lock                    # Reproducible dep lockfile
 ├── style_checker/             # Main package
 │   ├── __init__.py            # Version (__version__)
+│   ├── categories.py          # Single source of truth for VALID_CATEGORIES
 │   ├── cli.py                 # Local CLI entry point (qestyle)
 │   ├── action.py              # GitHub Action entry point
 │   ├── reviewer.py            # LLM review engine (shared)
 │   ├── fix_applier.py         # Apply fixes to files (shared)
 │   ├── github_handler.py      # GitHub API (action only)
-│   ├── prompt_loader.py       # Load prompts + rules (shared)
-│   ├── prompts/               # Minimal rule-agnostic prompts
-│   └── rules/                 # Category-specific rule definitions
+│   ├── prompts/               # Single shared prompt.md (+ v0.6.1 archive)
+│   └── rules/                 # Per-category rule definitions
 ├── tests/                     # Test suite
 ├── docs/                      # Documentation (this site)
 └── examples/                  # Example workflows
diff --git a/docs/developer/contributing.md b/docs/developer/contributing.md
index 6277723..a3cf097 100644
--- a/docs/developer/contributing.md
+++ b/docs/developer/contributing.md
@@ -88,16 +88,15 @@ Rules are in `style_checker/rules/` and are read directly by the LLM — **no co
    [Good and bad examples]
    ```
 
-3. Update corresponding prompt file in `style_checker/prompts/` if needed
+3. The base prompt (`prompts/prompt.md`) is shared across all categories; usually no edit needed there.
 4. Test with real lecture files
 
 ### Adding a New Category
 
-1. Create `prompts/category-prompt.md`
-2. Create `rules/category-rules.md`
-3. Add category to `VALID_CATEGORIES` in `github_handler.py` and `prompt_loader.py`
-4. Add to category list in `review_lecture_smart()`
-5. Test end-to-end
+1. Create `style_checker/rules/{category}-rules.md`
+2. Add the new name to `VALID_CATEGORIES` in `style_checker/categories.py`
+3. Add an entry for it in `RULE_EVALUATION_ORDER` in `style_checker/reviewer.py` (the test suite will fail loudly if the keys drift)
+4. Test end-to-end
 
 ## Pull Request Process
 
diff --git a/docs/developer/extended-thinking.md b/docs/developer/extended-thinking.md
index 7a8c6be..9907d86 100644
--- a/docs/developer/extended-thinking.md
+++ b/docs/developer/extended-thinking.md
@@ -117,5 +117,5 @@ This is 40 lines vs the previous 120-line category-specific prompts, and it prod
 |----------|-----------|
 | `thinking_budget=10000` | Enough for careful analysis, not excessive cost |
 | `temperature=1.0` | Required by Anthropic for extended thinking |
-| 8 identical prompt files (for now) | Consolidation to single file planned (validated on writing, pending other categories) |
+| Single shared `prompts/prompt.md` | Consolidated from 8 byte-identical files (validated on writing, then rolled out across all categories) |
 | Archive v0.6.1 prompts | Reference for regression testing and comparison |
diff --git a/docs/developer/roadmap.md b/docs/developer/roadmap.md
index a4c0f53..d147a44 100644
--- a/docs/developer/roadmap.md
+++ b/docs/developer/roadmap.md
@@ -28,7 +28,7 @@ The project is in **active development**. Breaking changes are acceptable — th
 ### Phase 3: Test Suite Improvements ✅
 
 - Fixed `test_parsing.py` to test real methods
-- Added tests for `fix_applier.py`, `prompt_loader.py`, `reviewer.py`
+- Added tests for `fix_applier.py`, `reviewer.py` (incl. RULE_EVALUATION_ORDER drift detection and prompt file existence)
 - Set up CI pipeline (GitHub Actions, ruff linting, Python 3.11/3.12/3.13)
 
 ## In Progress
@@ -44,7 +44,7 @@ Focus: reduce LLM hallucinations, improve fix accuracy, move mechanical rules to
 | 4.3 Deterministic Checkers | ~13 mechanical rules via regex (zero hallucination risk) | Planned |
 | 4.4 Rule Clarity | Improve 12 rule descriptions to reduce misinterpretation | Planned |
 | 4.5 Scope Reduction | Reduce noise from overly subjective rules | Planned |
-| 4.6 Prompt Consolidation | Merge 8 identical prompt files into single `prompt.md` | Planned |
+| 4.6 Prompt Consolidation | Merge 8 identical prompt files into single `prompt.md` | **Done** (PR #17) |
 | 4.7 Extended Thinking | Claude reasons internally → 0% false positives | **Done** (v0.7.0) |
 
 ### Phase 5: Style Suggestion UX
diff --git a/docs/developer/testing.md b/docs/developer/testing.md
index e48f7f9..6bd9c0a 100644
--- a/docs/developer/testing.md
+++ b/docs/developer/testing.md
@@ -27,8 +27,7 @@ tests/
 ├── test_github_handler.py    # GitHub API interaction, comment parsing
 ├── test_markdown_parser.py   # LLM response parsing
 ├── test_parsing.py           # Comment trigger pattern matching
-├── test_prompt_loader.py     # Prompt/rules file loading
-├── test_reviewer.py          # Rule extraction and evaluation order
+├── test_reviewer.py          # Rule extraction, RULE_EVALUATION_ORDER, prompt file
 ├── test_llm_integration.py   # Real LLM API calls (@integration)
 └── test_cli.py               # CLI argument parsing
 ```
@@ -43,8 +42,7 @@ Run automatically with `pytest`:
 | `test_github_handler.py` | GitHub API interaction, comment parsing |
 | `test_markdown_parser.py` | LLM response parsing |
 | `test_parsing.py` | Comment trigger pattern matching (real method) |
-| `test_prompt_loader.py` | Prompt/rules file loading |
-| `test_reviewer.py` | Rule extraction and evaluation order |
+| `test_reviewer.py` | Rule extraction, RULE_EVALUATION_ORDER consistency, prompt file existence |
 | `test_cli.py` | CLI argument parsing |
 
 ### Integration Tests (Slow, Costs Money)
@@ -69,15 +67,14 @@ pytest --cov=style_checker --cov-report=html
 open htmlcov/index.html
 ```
 
-Current coverage:
+Current coverage (approximate — re-measure with `pytest --cov`):
 
 | File | Coverage |
 |------|----------|
-| `fix_applier.py` | 92% |
-| `prompt_loader.py` | 86% |
-| `github_handler.py` | 55% |
-| `reviewer.py` | 47% |
-| `action.py` | 0% (needs integration mocking) |
+| `fix_applier.py` | high |
+| `github_handler.py` | medium |
+| `reviewer.py` | medium |
+| `action.py` | 0% (needs integration mocking — tracked in TECHNICAL-REVIEW §6.1) |
 
 ## CI Pipeline
 
diff --git a/style_checker/prompts/code-prompt.md b/style_checker/prompts/code-prompt.md
deleted file mode 100644
index 2508759..0000000
--- a/style_checker/prompts/code-prompt.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!-- Prompt Version: 0.7.0 | Last Updated: 2026-02-13 | Minimal rule-agnostic prompt with extended thinking -->
-
-You are a style checker for QuantEcon lecture files written in MyST Markdown.
-
-## Task
-
-Find all violations of the provided rule in the lecture document.
-
-First, silently analyze the entire document and identify candidate violations.
-Then, verify each candidate — confirm the current text actually violates the rule and the fix changes the text.
-Only include confirmed violations in your response. Report 0 if none exist.
-
-## Response Format
-
-```markdown
-# Review Results
-
-## Summary
-[1-2 sentence summary]
-
-## Issues Found
-[NUMBER ONLY]
-
-## Violations
-
-### Violation 1: [rule-code] - [Rule Title]
-**Severity:** error
-**Location:** Line [X] / Section "[name]"
-**Description:** [Why this violates the rule]
-**Current text:**
-~~~markdown
-[exact quote]
-~~~
-**Suggested fix:**
-~~~markdown
-[corrected version — MUST be different from current text]
-~~~
-**Explanation:** [Why this fix resolves the violation]
-```
-
-If Issues Found is 0, do not include a Violations section.
diff --git a/style_checker/prompts/figures-prompt.md b/style_checker/prompts/figures-prompt.md
deleted file mode 100644
index 2508759..0000000
--- a/style_checker/prompts/figures-prompt.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!-- Prompt Version: 0.7.0 | Last Updated: 2026-02-13 | Minimal rule-agnostic prompt with extended thinking -->
-
-You are a style checker for QuantEcon lecture files written in MyST Markdown.
-
-## Task
-
-Find all violations of the provided rule in the lecture document.
-
-First, silently analyze the entire document and identify candidate violations.
-Then, verify each candidate — confirm the current text actually violates the rule and the fix changes the text.
-Only include confirmed violations in your response. Report 0 if none exist.
-
-## Response Format
-
-```markdown
-# Review Results
-
-## Summary
-[1-2 sentence summary]
-
-## Issues Found
-[NUMBER ONLY]
-
-## Violations
-
-### Violation 1: [rule-code] - [Rule Title]
-**Severity:** error
-**Location:** Line [X] / Section "[name]"
-**Description:** [Why this violates the rule]
-**Current text:**
-~~~markdown
-[exact quote]
-~~~
-**Suggested fix:**
-~~~markdown
-[corrected version — MUST be different from current text]
-~~~
-**Explanation:** [Why this fix resolves the violation]
-```
-
-If Issues Found is 0, do not include a Violations section.
diff --git a/style_checker/prompts/jax-prompt.md b/style_checker/prompts/jax-prompt.md
deleted file mode 100644
index 2508759..0000000
--- a/style_checker/prompts/jax-prompt.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!-- Prompt Version: 0.7.0 | Last Updated: 2026-02-13 | Minimal rule-agnostic prompt with extended thinking -->
-
-You are a style checker for QuantEcon lecture files written in MyST Markdown.
-
-## Task
-
-Find all violations of the provided rule in the lecture document.
-
-First, silently analyze the entire document and identify candidate violations.
-Then, verify each candidate — confirm the current text actually violates the rule and the fix changes the text.
-Only include confirmed violations in your response. Report 0 if none exist.
-
-## Response Format
-
-```markdown
-# Review Results
-
-## Summary
-[1-2 sentence summary]
-
-## Issues Found
-[NUMBER ONLY]
-
-## Violations
-
-### Violation 1: [rule-code] - [Rule Title]
-**Severity:** error
-**Location:** Line [X] / Section "[name]"
-**Description:** [Why this violates the rule]
-**Current text:**
-~~~markdown
-[exact quote]
-~~~
-**Suggested fix:**
-~~~markdown
-[corrected version — MUST be different from current text]
-~~~
-**Explanation:** [Why this fix resolves the violation]
-```
-
-If Issues Found is 0, do not include a Violations section.
diff --git a/style_checker/prompts/links-prompt.md b/style_checker/prompts/links-prompt.md
deleted file mode 100644
index 2508759..0000000
--- a/style_checker/prompts/links-prompt.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!-- Prompt Version: 0.7.0 | Last Updated: 2026-02-13 | Minimal rule-agnostic prompt with extended thinking -->
-
-You are a style checker for QuantEcon lecture files written in MyST Markdown.
-
-## Task
-
-Find all violations of the provided rule in the lecture document.
-
-First, silently analyze the entire document and identify candidate violations.
-Then, verify each candidate — confirm the current text actually violates the rule and the fix changes the text.
-Only include confirmed violations in your response. Report 0 if none exist.
-
-## Response Format
-
-```markdown
-# Review Results
-
-## Summary
-[1-2 sentence summary]
-
-## Issues Found
-[NUMBER ONLY]
-
-## Violations
-
-### Violation 1: [rule-code] - [Rule Title]
-**Severity:** error
-**Location:** Line [X] / Section "[name]"
-**Description:** [Why this violates the rule]
-**Current text:**
-~~~markdown
-[exact quote]
-~~~
-**Suggested fix:**
-~~~markdown
-[corrected version — MUST be different from current text]
-~~~
-**Explanation:** [Why this fix resolves the violation]
-```
-
-If Issues Found is 0, do not include a Violations section.
diff --git a/style_checker/prompts/math-prompt.md b/style_checker/prompts/math-prompt.md
deleted file mode 100644
index 2508759..0000000
--- a/style_checker/prompts/math-prompt.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!-- Prompt Version: 0.7.0 | Last Updated: 2026-02-13 | Minimal rule-agnostic prompt with extended thinking -->
-
-You are a style checker for QuantEcon lecture files written in MyST Markdown.
-
-## Task
-
-Find all violations of the provided rule in the lecture document.
-
-First, silently analyze the entire document and identify candidate violations.
-Then, verify each candidate — confirm the current text actually violates the rule and the fix changes the text.
-Only include confirmed violations in your response. Report 0 if none exist.
-
-## Response Format
-
-```markdown
-# Review Results
-
-## Summary
-[1-2 sentence summary]
-
-## Issues Found
-[NUMBER ONLY]
-
-## Violations
-
-### Violation 1: [rule-code] - [Rule Title]
-**Severity:** error
-**Location:** Line [X] / Section "[name]"
-**Description:** [Why this violates the rule]
-**Current text:**
-~~~markdown
-[exact quote]
-~~~
-**Suggested fix:**
-~~~markdown
-[corrected version — MUST be different from current text]
-~~~
-**Explanation:** [Why this fix resolves the violation]
-```
-
-If Issues Found is 0, do not include a Violations section.
diff --git a/style_checker/prompts/admonitions-prompt.md b/style_checker/prompts/prompt.md
similarity index 100%
rename from style_checker/prompts/admonitions-prompt.md
rename to style_checker/prompts/prompt.md
diff --git a/style_checker/prompts/references-prompt.md b/style_checker/prompts/references-prompt.md
deleted file mode 100644
index 2508759..0000000
--- a/style_checker/prompts/references-prompt.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!-- Prompt Version: 0.7.0 | Last Updated: 2026-02-13 | Minimal rule-agnostic prompt with extended thinking -->
-
-You are a style checker for QuantEcon lecture files written in MyST Markdown.
-
-## Task
-
-Find all violations of the provided rule in the lecture document.
-
-First, silently analyze the entire document and identify candidate violations.
-Then, verify each candidate — confirm the current text actually violates the rule and the fix changes the text.
-Only include confirmed violations in your response. Report 0 if none exist.
-
-## Response Format
-
-```markdown
-# Review Results
-
-## Summary
-[1-2 sentence summary]
-
-## Issues Found
-[NUMBER ONLY]
-
-## Violations
-
-### Violation 1: [rule-code] - [Rule Title]
-**Severity:** error
-**Location:** Line [X] / Section "[name]"
-**Description:** [Why this violates the rule]
-**Current text:**
-~~~markdown
-[exact quote]
-~~~
-**Suggested fix:**
-~~~markdown
-[corrected version — MUST be different from current text]
-~~~
-**Explanation:** [Why this fix resolves the violation]
-```
-
-If Issues Found is 0, do not include a Violations section.
diff --git a/style_checker/prompts/writing-prompt.md b/style_checker/prompts/writing-prompt.md
deleted file mode 100644
index 2508759..0000000
--- a/style_checker/prompts/writing-prompt.md
+++ /dev/null
@@ -1,41 +0,0 @@
-<!-- Prompt Version: 0.7.0 | Last Updated: 2026-02-13 | Minimal rule-agnostic prompt with extended thinking -->
-
-You are a style checker for QuantEcon lecture files written in MyST Markdown.
-
-## Task
-
-Find all violations of the provided rule in the lecture document.
-
-First, silently analyze the entire document and identify candidate violations.
-Then, verify each candidate — confirm the current text actually violates the rule and the fix changes the text.
-Only include confirmed violations in your response. Report 0 if none exist.
-
-## Response Format
-
-```markdown
-# Review Results
-
-## Summary
-[1-2 sentence summary]
-
-## Issues Found
-[NUMBER ONLY]
-
-## Violations
-
-### Violation 1: [rule-code] - [Rule Title]
-**Severity:** error
-**Location:** Line [X] / Section "[name]"
-**Description:** [Why this violates the rule]
-**Current text:**
-~~~markdown
-[exact quote]
-~~~
-**Suggested fix:**
-~~~markdown
-[corrected version — MUST be different from current text]
-~~~
-**Explanation:** [Why this fix resolves the violation]
-```
-
-If Issues Found is 0, do not include a Violations section.
diff --git a/style_checker/reviewer.py b/style_checker/reviewer.py
index 6a41874..c0886fb 100644
--- a/style_checker/reviewer.py
+++ b/style_checker/reviewer.py
@@ -154,25 +154,28 @@ def extract_individual_rules(category: str) -> List[Dict[str, str]]:
 def create_single_rule_prompt(category: str, rule: Dict[str, str], lecture_content: str) -> str:
     """
     Create a focused prompt for checking a single rule.
-    
+
+    The base prompt is rule-agnostic — a single `prompts/prompt.md` is shared
+    across all categories. The `category` arg is currently unused but kept in
+    the signature so callers don't need to change if a category-specific
+    prompt is ever reintroduced.
+
     Args:
-        category: Category name (e.g., 'writing')
+        category: Category name (e.g., 'writing') — currently unused
         rule: Dict with 'rule_id', 'title', and 'content'
         lecture_content: The lecture to check
-        
+
     Returns:
         Complete prompt focused on one specific rule
     """
-    # Load the base prompt (without rules)
     prompts_dir = Path(__file__).parent / "prompts"
-    prompt_file = prompts_dir / f"{category}-prompt.md"
-    
+    prompt_file = prompts_dir / "prompt.md"
+
     if not prompt_file.exists():
         raise FileNotFoundError(f"Prompt file not found: {prompt_file}")
-    
-    with open(prompt_file, 'r') as f:
-        base_prompt = f.read()
-    
+
+    base_prompt = prompt_file.read_text()
+
     # Create focused prompt with single rule
     focused_prompt = f"""{base_prompt}
 
@@ -186,7 +189,7 @@ def create_single_rule_prompt(category: str, rule: Dict[str, str], lecture_conte
 
 {lecture_content}
 """
-    
+
     return focused_prompt
 
 def parse_markdown_response(response: str) -> Dict[str, Any]:
diff --git a/tests/README.md b/tests/README.md
index 1e06f48..9d72d0a 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -33,21 +33,14 @@ Tests the fix application engine:
 - First-occurrence-only replacement
 - Fix quality validation warnings
 
-### `test_prompt_loader.py`
-Tests prompt and rules loading:
-- Single and multi-category prompt loading
-- All 8 categories loadable
-- Invalid category error handling
-- Prompt version tracking presence
-- Rules file content validation
-
 ### `test_reviewer.py`
-Tests rule extraction and evaluation order:
+Tests rule extraction, evaluation order, and prompt-file invariants:
 - Rule counts per category (49 total)
 - Rule type distribution (32 rule, 13 style, 4 migrate)
-- RULE_EVALUATION_ORDER consistency with rule files
+- RULE_EVALUATION_ORDER consistency with rule files AND with VALID_CATEGORIES (drift detection)
 - Rule field validation and ID format
 - No duplicate rule IDs
+- Shared `prompts/prompt.md` exists and carries a version header
 
 ### `test_llm_integration.py`
 **Integration tests** that make real LLM API calls (marked with `@pytest.mark.integration`):
@@ -107,7 +100,8 @@ pytest -m integration -v
 
 Install test dependencies:
 ```bash
-pip install -r requirements.txt
+uv sync --all-extras       # recommended (uses uv.lock)
+# or: pip install -e ".[dev,action]"
 ```
 
 This includes:
diff --git a/tests/test_reviewer.py b/tests/test_reviewer.py
index 708e86d..9dd7fda 100644
--- a/tests/test_reviewer.py
+++ b/tests/test_reviewer.py
@@ -2,6 +2,9 @@
 Tests for reviewer.py — extract_individual_rules() and RULE_EVALUATION_ORDER
 """
 
+from pathlib import Path
+
+import style_checker
 from style_checker.categories import VALID_CATEGORIES
 from style_checker.reviewer import (
     extract_individual_rules,
@@ -9,6 +12,9 @@
 )
 
 
+PROMPTS_DIR = Path(style_checker.__file__).parent / "prompts"
+
+
 # Expected rule counts per category (from rule files)
 EXPECTED_RULE_COUNTS = {
     'writing': 8,
@@ -134,6 +140,29 @@ def test_no_extra_ids_in_order(self):
                     f"'{category}': '{rule_id}' in order but not in rule file"
 
 
+class TestPromptFile:
+    """Test the single shared prompt file used by create_single_rule_prompt.
+
+    Replaces coverage from the deleted test_prompt_loader.py — but for a
+    single consolidated prompt instead of one file per category.
+    """
+
+    def test_prompt_file_exists(self):
+        """create_single_rule_prompt() raises FileNotFoundError at runtime if
+        the prompt file is missing — assert at test time so we catch packaging
+        regressions before they hit production."""
+        prompt_file = PROMPTS_DIR / "prompt.md"
+        assert prompt_file.exists(), \
+            f"Shared prompt file missing: {prompt_file}"
+
+    def test_prompt_file_has_version_header(self):
+        """The prompt should carry a `<!-- Prompt Version: X.Y.Z ... -->` comment
+        so logs can record which prompt produced a given review."""
+        content = (PROMPTS_DIR / "prompt.md").read_text()
+        assert "Prompt Version:" in content, \
+            "prompt.md missing the 'Prompt Version: ...' header comment"
+
+
 class TestRuleTypeCounts:
     """Test that rule type distribution matches expectations"""