feat: Support jj (#217)

Co-authored-by: Codex <codex@openai.com>
Co-authored-by: Ben Vinegar <ben@benv.ca>

Author: 3 people

.github/workflows/ci.yml

@@ -30,6 +30,11 @@ jobs:
         with:
           bun-version: 1.3.10
 
+      - name: Install Jujutsu
+        uses: taiki-e/install-action@v2
+        with:
+          tool: jj-cli
+
       - name: Install dependencies
         run: bun install --frozen-lockfile
 

.github/workflows/pr-ci.yml

@@ -33,6 +33,11 @@ jobs:
         with:
           node-version: 22
 
+      - name: Install Jujutsu
+        uses: taiki-e/install-action@v2
+        with:
+          tool: jj-cli
+
       - name: Install dependencies
         run: bun install --frozen-lockfile
 

CHANGELOG.md

@@ -6,6 +6,8 @@ All notable user-visible changes to Hunk are documented in this file.
 
 ### Added
 
+- Added `vcs = "jj"` support, enabling `hunk diff [revset]` and `hunk show [revset]`.
+
 ### Changed
 
 ### Fixed

README.md

@@ -57,6 +57,18 @@ hunk show                      # review the latest commit
 hunk show HEAD~1               # review an earlier commit
 ```
 
+### Working with Jujutsu
+
+Set `vcs = "jj"` in config to use the same `hunk diff [revset]` and `hunk show [revset]` commands with Jujutsu revsets instead. When `vcs` is unset, Hunk uses Git.
+
+To use hunk as jj's pager, run `jj config edit --user` and update:
+
+```toml
+[ui]
+pager = ["hunk", "pager"]
+diff-formatter = ":git"
+```
+
 ### Working with raw files and patches
 
 ```bash
@@ -112,13 +124,14 @@ Example:
 ```toml
 theme = "graphite"   # graphite, midnight, paper, ember
 mode = "auto"        # auto, split, stack
+vcs = "git"          # git, jj
 exclude_untracked = false
 line_numbers = true
 wrap_lines = false
 agent_notes = false
 ```
 
-`exclude_untracked` affects working-tree `hunk diff` sessions only.
+`exclude_untracked` affects Git working-tree `hunk diff` sessions only.
 
 ### Git integration
 

benchmarks/bootstrap-load.ts

@@ -108,7 +108,7 @@ async function measureGitBootstrap(repoDir: string) {
   try {
     const endToEndStart = performance.now();
     const bootstrap = await loadAppBootstrap({
-      kind: "git",
+      kind: "vcs",
       staged: false,
       options: { mode: "auto" },
     });

benchmarks/highlight-prefetch.ts

@@ -53,7 +53,7 @@ function createDiffFile(index: number, marker: string): DiffFile {
 function createBootstrap(): AppBootstrap {
   return {
     input: {
-      kind: "git",
+      kind: "vcs",
       staged: false,
       options: {
         mode: "auto",

benchmarks/large-stream-fixture.ts

@@ -103,7 +103,7 @@ export function createLargeSplitStreamBootstrap({
 }: LargeSplitStreamFixtureOptions = {}): AppBootstrap {
   return {
     input: {
-      kind: "git",
+      kind: "vcs",
       staged: false,
       options: {
         mode: "auto",

src/core/cli.test.ts

@@ -87,7 +87,7 @@ describe("parseCli", () => {
     ]);
 
     expect(parsed).toMatchObject({
-      kind: "git",
+      kind: "vcs",
       range: "main...feature",
       staged: false,
       options: {
@@ -107,23 +107,23 @@ describe("parseCli", () => {
     const staged = await parseCli(["bun", "hunk", "diff", "--staged"]);
     const cached = await parseCli(["bun", "hunk", "diff", "--cached"]);
 
-    expect(staged).toMatchObject({ kind: "git", staged: true });
-    expect(cached).toMatchObject({ kind: "git", staged: true });
+    expect(staged).toMatchObject({ kind: "vcs", staged: true });
+    expect(cached).toMatchObject({ kind: "vcs", staged: true });
   });
 
   test("parses untracked file toggles for git diff", async () => {
     const excluded = await parseCli(["bun", "hunk", "diff", "--exclude-untracked"]);
     const included = await parseCli(["bun", "hunk", "diff", "--no-exclude-untracked"]);
 
     expect(excluded).toMatchObject({
-      kind: "git",
+      kind: "vcs",
       staged: false,
       options: {
         excludeUntracked: true,
       },
     });
     expect(included).toMatchObject({
-      kind: "git",
+      kind: "vcs",
       staged: false,
       options: {
         excludeUntracked: false,
@@ -162,12 +162,22 @@ describe("parseCli", () => {
     ]);
 
     expect(parsed).toMatchObject({
-      kind: "git",
+      kind: "vcs",
       range: "main",
       pathspecs: ["src/app.ts", "test/app.test.ts"],
     });
   });
 
+  test("parses target followed by pathspecs without a separator", async () => {
+    const parsed = await parseCli(["bun", "hunk", "diff", "trunk()..@", ".github"]);
+
+    expect(parsed).toMatchObject({
+      kind: "vcs",
+      range: "trunk()..@",
+      pathspecs: [".github"],
+    });
+  });
+
   test("parses show mode with optional ref and pathspecs", async () => {
     const parsed = await parseCli(["bun", "hunk", "show", "HEAD~1", "--", "src/app.ts"]);
 
@@ -364,7 +374,7 @@ describe("parseCli", () => {
       selector: { sessionPath: "/tmp/live-window" },
       sourcePath: "/tmp/source-repo",
       nextInput: {
-        kind: "git",
+        kind: "vcs",
         staged: false,
         options: {},
       },

src/core/cli.ts

@@ -126,11 +126,11 @@ function renderCliHelp() {
     "Desktop-inspired terminal diff viewer for agent-authored changesets.",
     "",
     "Commands:",
-    "  hunk diff [ref] [-- <pathspec...>]      review working tree changes or compare against a ref",
+    "  hunk diff [target] [-- <pathspec...>]   review working tree changes or compare against a target",
     "  hunk diff --staged [-- <pathspec...>]   review staged changes",
     "  hunk diff <left> <right>                compare two concrete files",
-    "  hunk show [ref] [-- <pathspec...>]      review the last commit or a given ref",
-    "  hunk stash show [ref]                   review a stash entry",
+    "  hunk show [target] [-- <pathspec...>]   review the last commit or a given target",
+    "  hunk stash show [ref]                   review a stash entry (git only)",
     "  hunk patch [file]                       review a patch file or stdin",
     "  hunk pager                              general Git pager wrapper with diff detection",
     "  hunk difftool <left> <right> [path]     review Git difftool file pairs",
@@ -159,6 +159,7 @@ function renderCliHelp() {
     "",
     "Notes:",
     "  Run `hunk <command> --help` for command-specific syntax and options.",
+    '  "target" refers to a generic set of changes; it can be a ref (git) or revset (jj)',
     "",
   ].join("\n");
 }
@@ -369,7 +370,7 @@ function resolveReloadSelector(
 async function parseDiffCommand(tokens: string[], argv: string[]): Promise<ParsedCliInput> {
   const { commandTokens, pathspecs } = splitPathspecArgs(tokens);
   const command = applyWatchOption(
-    createCommand("diff", "review Git diffs or compare two concrete files"),
+    createCommand("diff", "review diffs or compare two concrete files"),
   )
     .option("--staged", "show staged changes instead of the working tree")
     .option("--cached", "alias for --staged")
@@ -402,7 +403,7 @@ async function parseDiffCommand(tokens: string[], argv: string[]): Promise<Parse
 
   if (parsedTargets.length === 0) {
     return {
-      kind: "git",
+      kind: "vcs",
       staged,
       pathspecs: normalizedPathspecs,
       options,
@@ -411,30 +412,35 @@ async function parseDiffCommand(tokens: string[], argv: string[]): Promise<Parse
 
   if (parsedTargets.length === 1) {
     return {
-      kind: "git",
+      kind: "vcs",
       range: parsedTargets[0],
       staged,
       pathspecs: normalizedPathspecs,
       options,
     };
   }
 
-  if (
-    parsedTargets.length === 2 &&
-    !staged &&
-    !normalizedPathspecs &&
-    areExistingFiles(parsedTargets[0]!, parsedTargets[1]!)
-  ) {
+  if (!staged && !normalizedPathspecs) {
+    if (parsedTargets.length === 2 && areExistingFiles(parsedTargets[0]!, parsedTargets[1]!)) {
+      return {
+        kind: "diff",
+        left: parsedTargets[0]!,
+        right: parsedTargets[1]!,
+        options,
+      };
+    }
+
     return {
-      kind: "diff",
-      left: parsedTargets[0]!,
-      right: parsedTargets[1]!,
+      kind: "vcs",
+      range: parsedTargets[0]!,
+      staged,
+      pathspecs: parsedTargets.slice(1),
       options,
     };
   }
 
   throw new Error(
-    "Use `hunk diff <ref>`, `hunk diff <ref1>..<ref2>`, or `hunk diff <left> <right>` for file comparison.",
+    "Use `hunk diff [target] [-- pathspec...]`, `hunk diff <left> <right>` for file comparison.",
   );
 }
 

src/core/config.test.ts

@@ -128,15 +128,15 @@ describe("config resolution", () => {
     const cwd = createTempDir("hunk-config-cwd-");
     const defaultResolved = resolveConfiguredCliInput(
       {
-        kind: "git",
+        kind: "vcs",
         staged: false,
         options: {},
       },
       { cwd, env: { HOME: home } },
     );
     const overriddenResolved = resolveConfiguredCliInput(
       {
-        kind: "git",
+        kind: "vcs",
         staged: false,
         options: { excludeUntracked: false },
       },
@@ -145,7 +145,7 @@ describe("config resolution", () => {
     const noConfigHome = createTempDir("hunk-config-home-");
     const fallbackResolved = resolveConfiguredCliInput(
       {
-        kind: "git",
+        kind: "vcs",
         staged: false,
         options: {},
       },
@@ -157,6 +157,33 @@ describe("config resolution", () => {
     expect(fallbackResolved.input.options.excludeUntracked).toBe(false);
   });
 
+  test("defaults to git VCS mode and accepts jj from config", () => {
+    const home = createTempDir("hunk-config-home-");
+    mkdirSync(join(home, ".config", "hunk"), { recursive: true });
+    writeFileSync(join(home, ".config", "hunk", "config.toml"), 'vcs = "jj"\n');
+
+    const cwd = createTempDir("hunk-config-cwd-");
+    const defaultResolved = resolveConfiguredCliInput(
+      {
+        kind: "vcs",
+        staged: false,
+        options: {},
+      },
+      { cwd, env: { HOME: createTempDir("hunk-config-empty-home-") } },
+    );
+    const configuredResolved = resolveConfiguredCliInput(
+      {
+        kind: "vcs",
+        staged: false,
+        options: {},
+      },
+      { cwd, env: { HOME: home } },
+    );
+
+    expect(defaultResolved.input.options.vcs).toBe("git");
+    expect(configuredResolved.input.options.vcs).toBe("jj");
+  });
+
   test("loadAppBootstrap exposes resolved initial preferences to the UI", async () => {
     const home = createTempDir("hunk-config-home-");
     const repo = createTempDir("hunk-config-repo-");