This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

A VS Code extension ("Partial Diff") that lets users compare text selections within a file, across files, or against the clipboard using VS Code's built-in diff viewer.

• npm test — run all tests (mocha, TDD style)
• npm test -- --grep "pattern" — run a single test by name
• npm run lint — tslint
• npm run compile:dev — webpack dev build
• npm run compile:prod — clean + webpack prod build (output: dist/extension.js)
• npm run watch — webpack dev build in watch mode
• npm run prep — full pre-PR check (compile:prod + lint + test)
• npm run coverage — nyc coverage report

• Store git worktrees under .git-worktrees/<branch_name> relative to the repository root.
• <branch_name> must not contain /. Use a slash-free branch name when creating worktrees.

Entry flow: src/extension.ts → BootstrapperFactory → Bootstrapper → registers commands and content provider with VS Code.

Adaptor pattern: All VS Code API access is wrapped in adaptors (src/lib/adaptors/) so the core logic is testable without VS Code. TextEditor, WindowAdaptor, WorkspaceAdaptor, and CommandAdaptor each wrap a corresponding VS Code API surface.

Command pattern: Each user action is a Command (interface in src/lib/commands/command.ts) created by CommandFactory. Commands are either TEXT_EDITOR type (receive the active editor) or GENERAL type.

Diff flow: Commands store selections in SelectionInfoRegistry (keyed by text keys: reg1, reg2, clipboard, visible1, visible2). When a diff is requested, DiffPresenter builds partialdiff:// URIs and calls vscode.diff. VS Code then calls ContentProvider.provideTextDocumentContent() to resolve the URI back to text, applying normalization rules via TextProcessRuleApplier.

Text normalization: NormalisationRuleStore loads rules from user config and tracks active/inactive state. TextProcessRuleApplier applies active rules to text before it enters the diff view. The diff title uses ~ instead of ↔ when normalization is active.

• Framework: Mocha with TDD interface (suite/test, not describe/it)
• Mocking: testdouble (td) — helpers in src/test/helpers.ts provide mock(), mockType(), mockMethods(), verify, when, contains, any, and wrapVerify
• Test location: src/test/ mirrors src/lib/ structure
• Execution: Tests run directly via ts-node (not compiled first)