fix: use temp file for large diffs to avoid command-line length limits

README.md

@@ -46,27 +46,65 @@ That's it. No configuration, no setup wizards, no complexity.
 
 ## Extension Settings
 
-This extension keeps it simple with just two optional settings:
+This extension provides several optional settings to customize your experience:
 
-* `claude-commit.claudePath`: Custom path to Claude CLI executable (auto-detects by default)
-* `claude-commit.debugMode`: Enable debug output for troubleshooting
+- `claude-commit.claudePath`: Custom path to Claude CLI executable (auto-detects by default)
+- `claude-commit.debugMode`: Enable debug output for troubleshooting
+- `claude-commit.customInstructions`: Custom instructions for commit message generation
+- `claude-commit.instructionsFilePath`: Path to a file containing custom commit message instructions
 
 ## Configuration Examples
 
 ### Using a custom Claude path
+
 ```json
 {
     "claude-commit.claudePath": "/usr/local/bin/claude"
 }
 ```
 
 ### Debug mode for troubleshooting
+
 ```json
 {
     "claude-commit.debugMode": true
 }
 ```
 
+### Custom instructions (inline)
+
+Provide custom rules directly in your settings:
+
+```json
+{
+    "claude-commit.customInstructions": "Summarize changes into a single sentence suitable for release notes. Focus on user-facing impact rather than technical details."
+}
+```
+
+### Custom instructions (from file)
+
+Use a file to share commit message conventions across your team:
+
+```json
+{
+    "claude-commit.instructionsFilePath": ".vscode/copilot/commit-message-instructions.md"
+}
+```
+
+Then create `.vscode/copilot/commit-message-instructions.md`:
+
+```markdown
+# Commit Message Instructions
+
+- Summarize changes into a sentence for release notes
+- Focus on the "why" rather than the "what"
+- Use imperative mood (e.g., "Add feature" not "Added feature")
+- Maximum 50 characters for the subject line
+- Include ticket number if applicable: [TICKET-123] Subject
+```
+
+The file path can be relative (from workspace root) or absolute. If both file and inline instructions are provided, the file takes precedence.
+
 ## Troubleshooting
 
 ### Claude CLI not found

package.json

@@ -74,6 +74,16 @@
           "type": "boolean",
           "default": false,
           "description": "Enable debug mode to show CLI commands being executed"
+        },
+        "claude-commit.customInstructions": {
+          "type": "string",
+          "default": "",
+          "description": "Custom instructions for commit message generation (e.g., 'Summarize changes into a sentence for release notes')"
+        },
+        "claude-commit.instructionsFilePath": {
+          "type": "string",
+          "default": "",
+          "description": "Path to a file containing custom commit message instructions (e.g., '.vscode/copilot/commit-message-instructions.md')"
         }
       }
     }