Add commits page with graph, diff, file browser, and checkout

New features:
- Commits list with ASCII graph, hash, message, author, date
- Single commit diff view with per-file diffs
- File tree browser at any commit
- File content viewer at any commit
- Checkout entire commit (detached HEAD)
- Checkout selected files from a commit

New GitService methods: listCommits, getCommitDiff,
listFilesAtCommit, getFileContentAtCommit, checkoutCommit,
checkoutFilesFromCommit.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/main/java/be/seeseepuff/webgit/controller/RepoController.java

@@ -58,6 +58,65 @@ public class RepoController
 		return "manage";
 	}
 
+	@GetMapping("/repo/{name}/commits")
+	public String commits(@PathVariable String name, Model model) throws IOException
+	{
+		model.addAttribute("name", name);
+		model.addAttribute("commits", gitService.listCommits(name));
+		return "commits";
+	}
+
+	@GetMapping("/repo/{name}/commit/{hash}")
+	public String commitDetail(@PathVariable String name, @PathVariable String hash, Model model) throws IOException
+	{
+		model.addAttribute("name", name);
+		model.addAttribute("hash", hash);
+		model.addAttribute("shortHash", hash.substring(0, Math.min(7, hash.length())));
+		model.addAttribute("diffs", gitService.getCommitDiff(name, hash));
+		return "commit";
+	}
+
+	@GetMapping("/repo/{name}/tree/{hash}")
+	public String tree(@PathVariable String name, @PathVariable String hash,
+					   @RequestParam(required = false, defaultValue = "") String path, Model model) throws IOException
+	{
+		model.addAttribute("name", name);
+		model.addAttribute("hash", hash);
+		model.addAttribute("shortHash", hash.substring(0, Math.min(7, hash.length())));
+		model.addAttribute("path", path);
+		model.addAttribute("files", gitService.listFilesAtCommit(name, hash, path));
+		return "tree";
+	}
+
+	@GetMapping("/repo/{name}/blob/{hash}/**")
+	public String blob(@PathVariable String name, @PathVariable String hash,
+					   jakarta.servlet.http.HttpServletRequest request, Model model) throws IOException
+	{
+		String fullPath = request.getRequestURI();
+		String prefix = "/repo/" + name + "/blob/" + hash + "/";
+		String filePath = fullPath.substring(prefix.length());
+		model.addAttribute("name", name);
+		model.addAttribute("hash", hash);
+		model.addAttribute("filePath", filePath);
+		model.addAttribute("content", gitService.getFileContentAtCommit(name, hash, filePath));
+		return "blob";
+	}
+
+	@PostMapping("/repo/{name}/checkout-commit")
+	public String checkoutCommit(@PathVariable String name, @RequestParam String hash) throws IOException, GitAPIException
+	{
+		gitService.checkoutCommit(name, hash);
+		return "redirect:/repo/" + name + "/commits";
+	}
+
+	@PostMapping("/repo/{name}/checkout-files")
+	public String checkoutFiles(@PathVariable String name, @RequestParam String hash,
+								@RequestParam List<String> files) throws IOException, GitAPIException
+	{
+		gitService.checkoutFilesFromCommit(name, hash, files);
+		return "redirect:/repo/" + name + "/changes";
+	}
+
 	@PostMapping("/repo/{name}/checkout")
 	public String checkout(@PathVariable String name, @RequestParam String branch) throws IOException, GitAPIException
 	{

src/main/java/be/seeseepuff/webgit/model/CommitInfo.java

@@ -0,0 +1,15 @@
+package be.seeseepuff.webgit.model;
+
+import java.util.List;
+
+public record CommitInfo(
+	String hash,
+	String shortHash,
+	String message,
+	String author,
+	String date,
+	List<String> parentHashes,
+	String graphLine
+)
+{
+}

src/main/java/be/seeseepuff/webgit/model/DiffInfo.java

@@ -0,0 +1,10 @@
+package be.seeseepuff.webgit.model;
+
+public record DiffInfo(
+	String changeType,
+	String oldPath,
+	String newPath,
+	String diff
+)
+{
+}

src/main/java/be/seeseepuff/webgit/model/FileInfo.java

@@ -0,0 +1,8 @@
+package be.seeseepuff.webgit.model;
+
+public record FileInfo(
+	String path,
+	String type
+)
+{
+}

src/main/java/be/seeseepuff/webgit/service/GitService.java

@@ -1,18 +1,40 @@
 package be.seeseepuff.webgit.service;
 
 import be.seeseepuff.webgit.config.WebgitProperties;
+import be.seeseepuff.webgit.model.CommitInfo;
+import be.seeseepuff.webgit.model.DiffInfo;
+import be.seeseepuff.webgit.model.FileInfo;
 import lombok.RequiredArgsConstructor;
 import org.eclipse.jgit.api.Git;
 import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.diff.DiffEntry;
+import org.eclipse.jgit.diff.DiffFormatter;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectLoader;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.lib.StoredConfig;
+import org.eclipse.jgit.revplot.PlotCommit;
+import org.eclipse.jgit.revplot.PlotCommitList;
+import org.eclipse.jgit.revplot.PlotLane;
+import org.eclipse.jgit.revplot.PlotWalk;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevTree;
 import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
+import org.eclipse.jgit.treewalk.TreeWalk;
+import org.eclipse.jgit.treewalk.filter.PathFilter;
 import org.springframework.stereotype.Service;
 
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -244,6 +266,205 @@ public class GitService
 		}
 	}
 
+	public List<CommitInfo> listCommits(String name) throws IOException
+	{
+		try (Git git = openRepository(name))
+		{
+			Repository repo = git.getRepository();
+			try (PlotWalk plotWalk = new PlotWalk(repo))
+			{
+				ObjectId head = repo.resolve("HEAD");
+				if (head == null)
+					return List.of();
+				plotWalk.markStart(plotWalk.parseCommit(head));
+
+				PlotCommitList<PlotLane> plotCommitList = new PlotCommitList<>();
+				plotCommitList.source(plotWalk);
+				plotCommitList.fillTo(Integer.MAX_VALUE);
+
+				int maxLanes = 0;
+				for (PlotCommit<PlotLane> pc : plotCommitList)
+				{
+					if (pc.getLane() != null && pc.getLane().getPosition() + 1 > maxLanes)
+						maxLanes = pc.getLane().getPosition() + 1;
+				}
+
+				List<CommitInfo> commits = new ArrayList<>();
+				for (PlotCommit<PlotLane> pc : plotCommitList)
+				{
+					String graphLine = buildGraphLine(pc, maxLanes);
+					List<String> parents = Arrays.stream(pc.getParents())
+						.map(p -> p.getId().abbreviate(7).name())
+						.toList();
+
+					DateTimeFormatter fmt = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm")
+						.withZone(ZoneId.systemDefault());
+
+					commits.add(new CommitInfo(
+						pc.getId().getName(),
+						pc.getId().abbreviate(7).name(),
+						pc.getShortMessage(),
+						pc.getAuthorIdent().getName(),
+						fmt.format(Instant.ofEpochSecond(pc.getCommitTime())),
+						parents,
+						graphLine
+					));
+				}
+				return commits;
+			}
+		}
+	}
+
+	private String buildGraphLine(PlotCommit<PlotLane> pc, int maxLanes)
+	{
+		int lanePos = pc.getLane() != null ? pc.getLane().getPosition() : 0;
+		int width = Math.max(maxLanes, lanePos + 1);
+		char[] line = new char[width];
+		Arrays.fill(line, ' ');
+
+		// Mark passing-through lanes
+		for (int i = 0; i < pc.getChildCount(); i++)
+		{
+			PlotCommit child = (PlotCommit) pc.getChild(i);
+			if (child.getLane() != null)
+			{
+				int childPos = child.getLane().getPosition();
+				if (childPos < width)
+					line[childPos] = '|';
+			}
+		}
+
+		line[lanePos] = '*';
+		return new String(line);
+	}
+
+	public List<DiffInfo> getCommitDiff(String name, String commitHash) throws IOException
+	{
+		try (Git git = openRepository(name))
+		{
+			Repository repo = git.getRepository();
+			ObjectId commitId = repo.resolve(commitHash);
+			try (var walk = new org.eclipse.jgit.revwalk.RevWalk(repo))
+			{
+				RevCommit commit = walk.parseCommit(commitId);
+				RevTree newTree = commit.getTree();
+				RevTree oldTree = null;
+				if (commit.getParentCount() > 0)
+				{
+					RevCommit parent = walk.parseCommit(commit.getParent(0));
+					oldTree = parent.getTree();
+				}
+
+				ByteArrayOutputStream out = new ByteArrayOutputStream();
+				try (DiffFormatter df = new DiffFormatter(out))
+				{
+					df.setRepository(repo);
+					List<DiffEntry> diffs = df.scan(oldTree, newTree);
+					List<DiffInfo> result = new ArrayList<>();
+					for (DiffEntry diff : diffs)
+					{
+						out.reset();
+						df.format(diff);
+						result.add(new DiffInfo(
+							diff.getChangeType().name(),
+							diff.getOldPath(),
+							diff.getNewPath(),
+							out.toString(StandardCharsets.UTF_8)
+						));
+					}
+					return result;
+				}
+			}
+		}
+	}
+
+	public List<FileInfo> listFilesAtCommit(String name, String commitHash, String dirPath) throws IOException
+	{
+		try (Git git = openRepository(name))
+		{
+			Repository repo = git.getRepository();
+			ObjectId commitId = repo.resolve(commitHash);
+			try (var walk = new org.eclipse.jgit.revwalk.RevWalk(repo))
+			{
+				RevCommit commit = walk.parseCommit(commitId);
+				RevTree tree = commit.getTree();
+
+				List<FileInfo> files = new ArrayList<>();
+				try (TreeWalk tw = new TreeWalk(repo))
+				{
+					tw.addTree(tree);
+					tw.setRecursive(false);
+					if (dirPath != null && !dirPath.isEmpty())
+					{
+						tw.setFilter(PathFilter.create(dirPath));
+						// Walk into the directory
+						while (tw.next())
+						{
+							if (tw.isSubtree() && tw.getPathString().equals(dirPath))
+							{
+								tw.enterSubtree();
+								break;
+							}
+						}
+					}
+					while (tw.next())
+					{
+						if (dirPath != null && !dirPath.isEmpty() && !tw.getPathString().startsWith(dirPath + "/"))
+							continue;
+						String type = tw.isSubtree() ? "tree" : "blob";
+						files.add(new FileInfo(tw.getPathString(), type));
+					}
+				}
+				return files;
+			}
+		}
+	}
+
+	public String getFileContentAtCommit(String name, String commitHash, String filePath) throws IOException
+	{
+		try (Git git = openRepository(name))
+		{
+			Repository repo = git.getRepository();
+			ObjectId commitId = repo.resolve(commitHash);
+			try (var walk = new org.eclipse.jgit.revwalk.RevWalk(repo))
+			{
+				RevCommit commit = walk.parseCommit(commitId);
+				RevTree tree = commit.getTree();
+
+				try (TreeWalk tw = TreeWalk.forPath(repo, filePath, tree))
+				{
+					if (tw == null)
+						return null;
+					ObjectLoader loader = repo.open(tw.getObjectId(0));
+					return new String(loader.getBytes(), StandardCharsets.UTF_8);
+				}
+			}
+		}
+	}
+
+	public void checkoutCommit(String name, String commitHash) throws IOException, GitAPIException
+	{
+		try (Git git = openRepository(name))
+		{
+			git.checkout()
+				.setName(commitHash)
+				.call();
+		}
+	}
+
+	public void checkoutFilesFromCommit(String name, String commitHash, List<String> files) throws IOException, GitAPIException
+	{
+		try (Git git = openRepository(name))
+		{
+			var checkout = git.checkout().setStartPoint(commitHash);
+			for (String file : files)
+			{
+				checkout.addPath(file);
+			}
+			checkout.call();
+		}
+	}
+
 	public void push(String name) throws IOException, GitAPIException
 	{
 		try (Git git = openRepository(name))

src/main/resources/templates/blob.html

@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html xmlns:th="http://www.thymeleaf.org">
+<head>
+<title th:text="'File - ' + ${filePath}">File</title>
+</head>
+<body>
+<h2 th:text="${filePath}">file.txt</h2>
+
+<p>
+<a th:href="@{/repo/{name}/tree/{hash}(name=${name}, hash=${hash})}">&lt; Back to tree</a>
+|
+<a th:href="@{/repo/{name}/commits(name=${name})}">&lt; Back to commits</a>
+</p>
+
+<table border="0" cellpadding="4" cellspacing="0">
+<tr>
+<td>
+<form method="post" th:action="@{/repo/{name}/checkout-files(name=${name})}">
+<input type="hidden" name="hash" th:value="${hash}">
+<input type="hidden" name="files" th:value="${filePath}">
+<input type="submit" value="Checkout this file">
+</form>
+</td>
+</tr>
+</table>
+
+<h3>Content</h3>
+<pre th:text="${content}">File content here</pre>
+
+</body>
+</html>

src/main/resources/templates/commit.html

@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<html xmlns:th="http://www.thymeleaf.org">
+<head>
+<title th:text="'Commit ' + ${hash}">Commit</title>
+</head>
+<body>
+<h2>Commit <span th:text="${shortHash}"></span></h2>
+
+<p><a th:href="@{/repo/{name}/commits(name=${name})}">&lt; Back to commits</a></p>
+
+<table border="0" cellpadding="4" cellspacing="0">
+<tr>
+<td>
+<form method="post" th:action="@{/repo/{name}/checkout-commit(name=${name})}">
+<input type="hidden" name="hash" th:value="${hash}">
+<input type="submit" value="Checkout this commit">
+</form>
+</td>
+<td>
+<a th:href="@{/repo/{name}/tree/{hash}(name=${name}, hash=${hash})}">Browse files</a>
+</td>
+</tr>
+</table>
+
+<h3>Changed Files</h3>
+
+<form method="post" th:action="@{/repo/{name}/checkout-files(name=${name})}">
+<input type="hidden" name="hash" th:value="${hash}">
+<table border="1" cellpadding="4" cellspacing="0">
+<tr>
+<th></th>
+<th>Change</th>
+<th>File</th>
+</tr>
+<tr th:each="d : ${diffs}">
+<td><input type="checkbox" name="files" th:value="${d.newPath}"></td>
+<td th:text="${d.changeType}"></td>
+<td th:text="${d.changeType == 'DELETE' ? d.oldPath : d.newPath}"></td>
+</tr>
+</table>
+<br>
+<input type="submit" value="Checkout selected files">
+</form>
+
+<h3>Diff</h3>
+<th:block th:each="d : ${diffs}">
+<h4 th:text="${d.changeType == 'DELETE' ? d.oldPath : d.newPath}"></h4>
+<pre th:text="${d.diff}"></pre>
+</th:block>
+
+</body>
+</html>

src/main/resources/templates/commits.html

@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<html xmlns:th="http://www.thymeleaf.org">
+<head>
+<title th:text="'Commits - ' + ${name}">Commits</title>
+</head>
+<body>
+<h2>Commits</h2>
+
+<table border="1" cellpadding="4" cellspacing="0">
+<tr>
+<th>Graph</th>
+<th>Hash</th>
+<th>Message</th>
+<th>Author</th>
+<th>Date</th>
+<th></th>
+<th></th>
+<th></th>
+</tr>
+<tr th:each="c : ${commits}">
+<td><pre th:text="${c.graphLine}" style="margin:0"></pre></td>
+<td><a th:href="@{/repo/{name}/commit/{hash}(name=${name}, hash=${c.hash})}" th:text="${c.shortHash}"></a></td>
+<td th:text="${c.message}"></td>
+<td th:text="${c.author}"></td>
+<td th:text="${c.date}"></td>
+<td><a th:href="@{/repo/{name}/tree/{hash}(name=${name}, hash=${c.hash})}">Browse</a></td>
+<td>
+<form method="post" th:action="@{/repo/{name}/checkout-commit(name=${name})}">
+<input type="hidden" name="hash" th:value="${c.hash}">
+<input type="submit" value="Checkout">
+</form>
+</td>
+<td><a th:href="@{/repo/{name}/commit/{hash}(name=${name}, hash=${c.hash})}">Diff</a></td>
+</tr>
+</table>
+
+<p th:if="${commits.isEmpty()}">No commits yet.</p>
+
+</body>
+</html>

src/main/resources/templates/nav.html

@@ -20,6 +20,7 @@
 <hr>
 <b th:text="${selectedRepo}"></b><br>
 <a th:href="@{/repo/{name}/changes(name=${selectedRepo})}" target="content">Staging</a><br>
+<a th:href="@{/repo/{name}/commits(name=${selectedRepo})}" target="content">Commits</a><br>
 <a th:href="@{/repo/{name}/branches(name=${selectedRepo})}" target="content">Branches</a><br>
 <a th:href="@{/repo/{name}/remote(name=${selectedRepo})}" target="content">Remote</a><br>
 <a th:href="@{/repo/{name}/manage(name=${selectedRepo})}" target="content">Manage</a><br>

src/main/resources/templates/tree.html

@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html xmlns:th="http://www.thymeleaf.org">
+<head>
+<title th:text="'Browse - ' + ${shortHash}">Browse</title>
+</head>
+<body>
+<h2>Browse <span th:text="${shortHash}"></span></h2>
+
+<p><a th:href="@{/repo/{name}/commits(name=${name})}">&lt; Back to commits</a></p>
+
+<p th:if="${!path.isEmpty()}">
+Path: <b th:text="${path}"></b>
+<br>
+<a th:href="@{/repo/{name}/tree/{hash}(name=${name}, hash=${hash}, path=${path.contains('/') ? path.substring(0, path.lastIndexOf('/')) : ''})}">&lt; Parent directory</a>
+</p>
+
+<table border="1" cellpadding="4" cellspacing="0">
+<tr>
+<th>Type</th>
+<th>Name</th>
+</tr>
+<tr th:each="f : ${files}">
+<td th:text="${f.type}"></td>
+<td>
+<a th:if="${f.type == 'tree'}" th:href="@{/repo/{name}/tree/{hash}(name=${name}, hash=${hash}, path=${f.path})}" th:text="${f.path.contains('/') ? f.path.substring(f.path.lastIndexOf('/') + 1) : f.path}"></a>
+<a th:if="${f.type == 'blob'}" th:href="@{'/repo/' + ${name} + '/blob/' + ${hash} + '/' + ${f.path}}" th:text="${f.path.contains('/') ? f.path.substring(f.path.lastIndexOf('/') + 1) : f.path}"></a>
+</td>
+</tr>
+</table>
+
+<p th:if="${files.isEmpty()}">Empty directory.</p>
+
+</body>
+</html>

src/test/java/be/seeseepuff/webgit/controller/RepoControllerTest.java

@@ -213,4 +213,81 @@ class RepoControllerTest
 
 		verify(gitService).deleteRepository("myrepo");
 	}
+
+	@Test
+	void commitsPageShowsCommits() throws Exception
+	{
+		when(gitService.listCommits("myrepo")).thenReturn(List.of(
+			new be.seeseepuff.webgit.model.CommitInfo("abc1234567890", "abc1234", "Initial commit", "author", "2026-01-01 12:00", List.of(), "*")
+		));
+
+		mockMvc.perform(get("/repo/myrepo/commits"))
+			.andExpect(status().isOk())
+			.andExpect(view().name("commits"))
+			.andExpect(model().attribute("name", "myrepo"))
+			.andExpect(content().string(org.hamcrest.Matchers.containsString("abc1234")))
+			.andExpect(content().string(org.hamcrest.Matchers.containsString("Initial commit")));
+	}
+
+	@Test
+	void commitDetailShowsDiff() throws Exception
+	{
+		when(gitService.getCommitDiff("myrepo", "abc1234")).thenReturn(List.of(
+			new be.seeseepuff.webgit.model.DiffInfo("ADD", "/dev/null", "file.txt", "+hello")
+		));
+
+		mockMvc.perform(get("/repo/myrepo/commit/abc1234"))
+			.andExpect(status().isOk())
+			.andExpect(view().name("commit"))
+			.andExpect(model().attribute("hash", "abc1234"))
+			.andExpect(content().string(org.hamcrest.Matchers.containsString("file.txt")));
+	}
+
+	@Test
+	void treeShowsFiles() throws Exception
+	{
+		when(gitService.listFilesAtCommit("myrepo", "abc1234", "")).thenReturn(List.of(
+			new be.seeseepuff.webgit.model.FileInfo("README.md", "blob")
+		));
+
+		mockMvc.perform(get("/repo/myrepo/tree/abc1234"))
+			.andExpect(status().isOk())
+			.andExpect(view().name("tree"))
+			.andExpect(content().string(org.hamcrest.Matchers.containsString("README.md")));
+	}
+
+	@Test
+	void blobShowsFileContent() throws Exception
+	{
+		when(gitService.getFileContentAtCommit("myrepo", "abc1234", "README.md")).thenReturn("# Hello");
+
+		mockMvc.perform(get("/repo/myrepo/blob/abc1234/README.md"))
+			.andExpect(status().isOk())
+			.andExpect(view().name("blob"))
+			.andExpect(content().string(org.hamcrest.Matchers.containsString("# Hello")));
+	}
+
+	@Test
+	void checkoutCommitRedirectsToCommits() throws Exception
+	{
+		mockMvc.perform(post("/repo/myrepo/checkout-commit")
+				.param("hash", "abc1234"))
+			.andExpect(status().is3xxRedirection())
+			.andExpect(redirectedUrl("/repo/myrepo/commits"));
+
+		verify(gitService).checkoutCommit("myrepo", "abc1234");
+	}
+
+	@Test
+	void checkoutFilesRedirectsToChanges() throws Exception
+	{
+		mockMvc.perform(post("/repo/myrepo/checkout-files")
+				.param("hash", "abc1234")
+				.param("files", "a.txt")
+				.param("files", "b.txt"))
+			.andExpect(status().is3xxRedirection())
+			.andExpect(redirectedUrl("/repo/myrepo/changes"));
+
+		verify(gitService).checkoutFilesFromCommit("myrepo", "abc1234", List.of("a.txt", "b.txt"));
+	}
 }

src/test/java/be/seeseepuff/webgit/service/GitServiceTest.java

@@ -333,4 +333,90 @@ class GitServiceTest
 		var remotes = gitService.listRemotes("myrepo");
 		assertEquals("https://new-url.com/repo.git", remotes.get("origin"));
 	}
+
+	@Test
+	void listCommitsReturnsCommitHistory() throws GitAPIException, IOException
+	{
+		gitService.cloneRepository(bareRemote.toUri().toString(), "myrepo");
+
+		var commits = gitService.listCommits("myrepo");
+		assertFalse(commits.isEmpty());
+		assertEquals("Initial commit", commits.getFirst().message());
+		assertNotNull(commits.getFirst().hash());
+		assertNotNull(commits.getFirst().shortHash());
+		assertNotNull(commits.getFirst().author());
+		assertNotNull(commits.getFirst().date());
+		assertNotNull(commits.getFirst().graphLine());
+	}
+
+	@Test
+	void getCommitDiffReturnsDiffs() throws GitAPIException, IOException
+	{
+		gitService.cloneRepository(bareRemote.toUri().toString(), "myrepo");
+
+		var commits = gitService.listCommits("myrepo");
+		var diffs = gitService.getCommitDiff("myrepo", commits.getFirst().hash());
+		assertFalse(diffs.isEmpty());
+		assertEquals("ADD", diffs.getFirst().changeType());
+		assertEquals("README.md", diffs.getFirst().newPath());
+		assertFalse(diffs.getFirst().diff().isEmpty());
+	}
+
+	@Test
+	void listFilesAtCommitReturnsFiles() throws GitAPIException, IOException
+	{
+		gitService.cloneRepository(bareRemote.toUri().toString(), "myrepo");
+
+		var commits = gitService.listCommits("myrepo");
+		var files = gitService.listFilesAtCommit("myrepo", commits.getFirst().hash(), "");
+		assertFalse(files.isEmpty());
+		assertTrue(files.stream().anyMatch(f -> f.path().equals("README.md")));
+	}
+
+	@Test
+	void getFileContentAtCommitReturnsContent() throws GitAPIException, IOException
+	{
+		gitService.cloneRepository(bareRemote.toUri().toString(), "myrepo");
+
+		var commits = gitService.listCommits("myrepo");
+		String content = gitService.getFileContentAtCommit("myrepo", commits.getFirst().hash(), "README.md");
+		assertEquals("# Test", content);
+	}
+
+	@Test
+	void getFileContentAtCommitReturnsNullForMissingFile() throws GitAPIException, IOException
+	{
+		gitService.cloneRepository(bareRemote.toUri().toString(), "myrepo");
+
+		var commits = gitService.listCommits("myrepo");
+		String content = gitService.getFileContentAtCommit("myrepo", commits.getFirst().hash(), "nonexistent.txt");
+		assertNull(content);
+	}
+
+	@Test
+	void checkoutCommitDetachesHead() throws GitAPIException, IOException
+	{
+		gitService.cloneRepository(bareRemote.toUri().toString(), "myrepo");
+
+		var commits = gitService.listCommits("myrepo");
+		gitService.checkoutCommit("myrepo", commits.getFirst().hash());
+
+		String head = gitService.getCurrentBranch("myrepo");
+		// Detached HEAD returns the commit hash
+		assertTrue(head.matches("[0-9a-f]+"));
+	}
+
+	@Test
+	void checkoutFilesFromCommitRestoresFiles() throws GitAPIException, IOException
+	{
+		gitService.cloneRepository(bareRemote.toUri().toString(), "myrepo");
+		// Modify a file
+		Path readme = worktreePath.resolve("myrepo").resolve("README.md");
+		Files.writeString(readme, "modified");
+
+		var commits = gitService.listCommits("myrepo");
+		gitService.checkoutFilesFromCommit("myrepo", commits.getFirst().hash(), List.of("README.md"));
+
+		assertEquals("# Test", Files.readString(readme));
+	}
 }