diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index f4b3629..1c59480 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -41,12 +41,10 @@ action-style-guide/
 │   ├── reviewer.py              # LLM interaction with extended thinking (shared)
 │   ├── github_handler.py        # GitHub API interactions (action only)
 │   ├── fix_applier.py           # Apply fixes to markdown files (shared)
-│   ├── prompt_loader.py         # Load prompts and rules (shared)
-│   ├── prompts/                 # Minimal rule-agnostic prompt (identical for all categories)
-│   │   ├── writing-prompt.md
-│   │   ├── math-prompt.md
-│   │   ├── ...
-│   │   └── v0.6.1/             # Archived previous prompts
+│   ├── categories.py            # Single source of truth for category names (VALID_CATEGORIES)
+│   ├── prompts/                 # Single rule-agnostic prompt, shared across all categories
+│   │   ├── prompt.md            # The shared prompt
+│   │   └── v0.6.1/              # Archived previous (per-category) prompts
 │   └── rules/                   # Category-specific rules
 │       ├── writing-rules.md
 │       ├── math-rules.md
@@ -81,9 +79,9 @@ action-style-guide/
 - **Single source of truth**: Version in `__init__.py`
 
 ### Prompt Files
-- **Location**: `style_checker/prompts/*.md`
-- **Design**: All 8 prompt files are identical (rule-agnostic). Consolidation to single `prompt.md` planned (see PLAN.md 4.6).
-- **Version tracking**: Each prompt has version comment at top: `<!-- Prompt Version: X.Y.Z | Last Updated: YYYY-MM-DD | Description -->`
+- **Location**: `style_checker/prompts/prompt.md`
+- **Design**: A single rule-agnostic prompt shared across all 8 categories (consolidated in #17; previously one identical file per category).
+- **Version tracking**: The prompt has a version comment at top: `<!-- Prompt Version: X.Y.Z | Last Updated: YYYY-MM-DD | Description -->`
 - **Archive**: Previous prompts archived in `style_checker/prompts/v0.6.1/`
 
 ### GitHub Integration