Merge & Blame

An IntelliJ-style three-way merge editor and Git blame for VS Code.

Try the live preview with representative merge samples, apply/ignore controls, magic wands, and demo blame history. All demo edits stay in your browser.

Local → editable Result ← Incoming

Apply or ignore individual changes using the arrows and × buttons beside the code. All merging runs locally with deterministic algorithms. No AI service, telemetry, Java runtime, or JetBrains installation is required to use it.

Install and use

1. Install the generated merge-and-blame-0.3.0.vsix using Extensions: Install from VSIX… in VS Code's Command Palette.
2. With a conflicted Git repository open, run Merge & Blame: Resolve Git Conflicts and select a file. You can also right-click a file under Merge Changes in Source Control and select Merge & Blame: Open File.
3. Resolve changes and review the middle pane. Save writes the result without staging it. Apply Changes saves and stages that file once all its changes are resolved. Finish the repository's merge or rebase in your usual Git workflow.

The result initially contains the common ancestor. Enable threeWayMerger.autoApplyNonConflicting to apply non-conflicting changes on open. Saved sessions retain both the result and resolution state when reopened.

Git blame

Right-click a file's line numbers → Show Git Blame. Colored date-and-author annotations appear beside the code in the native VS Code editor. Its language features, extensions, selections, undo history, and unsaved text stay available. Hide Git Blame removes the annotations without reopening the file.

Hover an annotation or its code line and click Open commit to open VS Code's native commit diff, with the blamed historical file first and focused. All files changed in the commit are included, comparing the parent with the commit. A custom viewer is used only if VS Code's built-in Git API is unavailable; it shows an inline diff with highlighted removals/additions and one scrollbar. The gutter also offers Open Commit for Blamed Line. Uncommitted lines display Not committed yet and have no commit link. Annotations refresh after edits, when returning to the editor, and on repository changes reported by VS Code's Git extension.

Annotations are installed for the complete buffer. Vertical scrolling does not fetch blame or wait for the extension host, including over SSH. The annotation column keeps its width while edited text is being reattributed.

VS Code's public decoration API does not provide direct click handlers or a separate fixed annotation gutter. Native blame therefore uses hover links and annotations that scroll horizontally with the text. These are differences from IDEA's exact click/scroll behavior. Each custom merge pane retains its directly clickable annotation column and uses that side's Git revision.

Controls

The current file's line endings, UTF-8 BOM, and permissions are preserved when saving. Changes to the file or conflict stages outside the editor stop a save instead of overwriting them. Existing marker-free manual results are imported when no saved session is available.

Rebase labels identify Git's stage 2 as the rebased-onto version and stage 3 as the commit being replayed. Neither side is assumed to mean “my feature branch” in every operation.

Develop

Requires Node.js 22+ and Git. VS Code 1.100+ is the extension target.

npm ci
npm run typecheck
npm test
npm run build
npm run test:ui
npm run package

Press F5 in this repository to launch an Extension Development Host. Open a repository with actual Git conflicts in that window. npm run preview also serves a standalone demonstration at http://127.0.0.1:4173. It opens a 195-line example covering 17 change cases, including pure insertions from both sides and text inserted within an existing line. Use the Preview selector for focused insertion, deletion, replacement, conflict, and file-boundary samples; Reset sample restores the original example. Samples can be linked directly, for example http://127.0.0.1:4173/?sample=insertions. The demo does not write or stage files. Its gutter also previews blame and the commit view using explicitly labeled example history; the installed extension reads real history from Git.

npm run build:preview writes a standalone static site to site/. Asset URLs are relative so the demo works below a GitHub Pages project path. Pushes to main run the tests, build the VSIX, and deploy this site through GitHub Actions.

Browser tests use an installed Chrome. npm run test:host launches an isolated VS Code profile and temporary Git repository, exercises the real extension UI, and verifies the resulting working tree and index. Set VSCODE_EXECUTABLE if VS Code is installed elsewhere. Set MERGER_TEST_AUTO=1 to also exercise automatic initial application and its native undo lifecycle. npm run test:blame separately verifies annotations, historical commit/file selection, unsaved edits, native editor retention, TypeScript hovers, blank lines, scrolling with a paused extension host, native commit diffs, commit refresh, and native save/undo. Run MERGER_TEST_LEGACY=1 npm run test:blame to check upgrading an open, unsaved blame tab from 0.2.1 to the current VSIX, including UTF-8 BOM and CRLF preservation. Build the current VSIX first; set MERGER_TEST_LEGACY_VSIX if the old package is stored elsewhere. MERGER_TEST_FALLBACK_COMMIT=1 npm run test:blame disables VS Code's Git extension and checks the fallback's highlighted parent/commit diff and single scrollbar.

npm run test:reference compares 1,626 default text-resolver cases and 1,000 line-range cases with an installed JetBrains IDE. Set JETBRAINS_HOME to its Contents directory (or a directory containing lib/ on other platforms). This is a development check only.

See development.md for the goal and docs/intellij-reference.md for the source revision, test provenance, architecture, and fidelity differences. See docs/publishing.md for publishing through GitHub Actions with Marketplace Trusted Publishing, and for the extension's new identity.

Scope

Supports UTF-8 text conflicts, including add/add and modify/delete conflicts. Binary, symlink, and submodule conflicts are rejected with an explanation. The extension is an independent implementation of the text merge workflow; it does not include IntelliJ's language-specific PSI/import resolvers. Editor services come from the embedded Monaco editors; other VS Code extensions' language features are not automatically hosted inside the webview.

Apache-2.0. See LICENSE, NOTICE, and THIRD_PARTY_NOTICES.txt.

This is an independent project and is not affiliated with or endorsed by JetBrains.