diff --git a/src/commands/commit.ts b/src/commands/commit.ts
index 88e7aeb..71747ec 100644
--- a/src/commands/commit.ts
+++ b/src/commands/commit.ts
@@ -1,7 +1,7 @@
 import { Command } from "commander";
 import * as git from "../lib/git.ts";
 import { LogManager } from "../lib/log-manager.ts";
-import { requireFilesystem } from "../lib/storage.ts";
+import { requireGit } from "../lib/storage.ts";
 import type { WikiContext } from "../types.ts";
 
 export function makeCommitCommand(): Command {
@@ -10,7 +10,7 @@ export function makeCommitCommand(): Command {
     .argument("[message]", "commit message")
     .action(async function (this: Command, message: string | undefined) {
       const ctx: WikiContext = this.optsWithGlobals().wikiContext;
-      requireFilesystem(ctx, "commit");
+      requireGit(ctx, "commit");
 
       // Auto-generate message from last log entry if not provided
       if (!message) {
diff --git a/src/commands/diff.ts b/src/commands/diff.ts
index c0a36f1..e883c1c 100644
--- a/src/commands/diff.ts
+++ b/src/commands/diff.ts
@@ -1,6 +1,6 @@
 import { Command } from "commander";
 import * as git from "../lib/git.ts";
-import { requireFilesystem } from "../lib/storage.ts";
+import { requireGit } from "../lib/storage.ts";
 import type { WikiContext } from "../types.ts";
 
 export function makeDiffCommand(): Command {
@@ -9,7 +9,7 @@ export function makeDiffCommand(): Command {
     .argument("[ref]", "commit ref to show (default: uncommitted changes)")
     .action(async function (this: Command, ref: string | undefined) {
       const ctx: WikiContext = this.optsWithGlobals().wikiContext;
-      requireFilesystem(ctx, "diff");
+      requireGit(ctx, "diff");
       const result = await git.diff(ctx.root, ref);
 
       if (!result.ok) {
diff --git a/src/commands/history.ts b/src/commands/history.ts
index aa42367..6cc4832 100644
--- a/src/commands/history.ts
+++ b/src/commands/history.ts
@@ -1,6 +1,6 @@
 import { Command } from "commander";
 import * as git from "../lib/git.ts";
-import { requireFilesystem } from "../lib/storage.ts";
+import { requireGit } from "../lib/storage.ts";
 import type { WikiContext } from "../types.ts";
 
 export function makeHistoryCommand(): Command {
@@ -14,7 +14,7 @@ export function makeHistoryCommand(): Command {
       options: { last: string },
     ) {
       const ctx: WikiContext = this.optsWithGlobals().wikiContext;
-      requireFilesystem(ctx, "history");
+      requireGit(ctx, "history");
       const limit = parseInt(options.last, 10);
 
       let result;
diff --git a/src/commands/init.ts b/src/commands/init.ts
index 67cf9e2..bcdea9a 100644
--- a/src/commands/init.ts
+++ b/src/commands/init.ts
@@ -10,7 +10,7 @@ import {
   getDefaultIndex,
   getDefaultLog,
 } from "../lib/templates.ts";
-import type { RegistryEntry } from "../types.ts";
+import type { BackendType, RegistryEntry } from "../types.ts";
 
 export function makeInitCommand(): Command {
   return new Command("init")
@@ -18,11 +18,13 @@ export function makeInitCommand(): Command {
     .argument("[dir]", "directory to initialize (defaults to cwd)")
     .option("-n, --name <name>", "wiki name")
     .option("-d, --domain <domain>", "knowledge domain", "general")
+    .option("-b, --backend <type>", "storage backend (filesystem, git, supabase)", "filesystem")
     .action(
       async (
         dir: string | undefined,
-        options: { name?: string; domain: string },
+        options: { name?: string; domain: string; backend: string },
       ) => {
+        const backend = options.backend as BackendType;
         const targetDir = resolve(dir ?? ".");
         const name = options.name ?? basename(targetDir);
         const domain = options.domain;
@@ -41,7 +43,7 @@ export function makeInitCommand(): Command {
         await Promise.all(dirs.map((d) => mkdir(d, { recursive: true })));
 
         // Write config
-        const config = getDefaultConfig(name, domain);
+        const config = getDefaultConfig(name, domain, backend);
         await saveConfig(targetDir, config);
 
         // Write template files
@@ -51,20 +53,22 @@ export function makeInitCommand(): Command {
           writeFile(resolve(targetDir, "wiki/log.md"), getDefaultLog(), "utf-8"),
         ]);
 
-        // Git init + initial commit
-        const initResult = await git.init(targetDir);
-        if (!initResult.ok) {
-          console.error(`Warning: git init failed: ${initResult.output}`);
-        } else {
-          await git.addAll(targetDir);
-          const commitResult = await git.commit(
-            targetDir,
-            "Initialize wiki",
-          );
-          if (!commitResult.ok) {
-            console.error(
-              `Warning: initial commit failed: ${commitResult.output}`,
+        // Git init + initial commit (git backend only)
+        if (backend === "git") {
+          const initResult = await git.init(targetDir);
+          if (!initResult.ok) {
+            console.error(`Warning: git init failed: ${initResult.output}`);
+          } else {
+            await git.addAll(targetDir);
+            const commitResult = await git.commit(
+              targetDir,
+              "Initialize wiki",
             );
+            if (!commitResult.ok) {
+              console.error(
+                `Warning: initial commit failed: ${commitResult.output}`,
+              );
+            }
           }
         }
 
diff --git a/src/commands/pull.ts b/src/commands/pull.ts
index 59f8602..d9d0c6b 100644
--- a/src/commands/pull.ts
+++ b/src/commands/pull.ts
@@ -1,6 +1,6 @@
 import { Command } from "commander";
 import * as git from "../lib/git.ts";
-import { requireFilesystem } from "../lib/storage.ts";
+import { requireGit } from "../lib/storage.ts";
 import type { WikiContext } from "../types.ts";
 
 export function makePullCommand(): Command {
@@ -8,7 +8,7 @@ export function makePullCommand(): Command {
     .description("Pull wiki changes from remote")
     .action(async function (this: Command) {
       const ctx: WikiContext = this.optsWithGlobals().wikiContext;
-      requireFilesystem(ctx, "pull");
+      requireGit(ctx, "pull");
 
       if (!(await git.hasRemote(ctx.root))) {
         console.error('No remote configured. Use "wiki repo connect" to add one.');
diff --git a/src/commands/push.ts b/src/commands/push.ts
index eb757d2..169ff97 100644
--- a/src/commands/push.ts
+++ b/src/commands/push.ts
@@ -1,6 +1,6 @@
 import { Command } from "commander";
 import * as git from "../lib/git.ts";
-import { requireFilesystem } from "../lib/storage.ts";
+import { requireGit } from "../lib/storage.ts";
 import type { WikiContext } from "../types.ts";
 
 export function makePushCommand(): Command {
@@ -8,7 +8,7 @@ export function makePushCommand(): Command {
     .description("Push wiki changes to remote")
     .action(async function (this: Command) {
       const ctx: WikiContext = this.optsWithGlobals().wikiContext;
-      requireFilesystem(ctx, "push");
+      requireGit(ctx, "push");
 
       if (!(await git.hasRemote(ctx.root))) {
         console.error('No remote configured. Use "wiki repo connect" to add one.');
diff --git a/src/commands/status.ts b/src/commands/status.ts
index 45d40b8..d3055a2 100644
--- a/src/commands/status.ts
+++ b/src/commands/status.ts
@@ -49,7 +49,7 @@ export function makeStatusCommand(): Command {
 
       // Git info (filesystem backend only)
       let gitInfo = { commits: "N/A", hasRemote: false };
-      if ((ctx.config.backend ?? "filesystem") === "filesystem") {
+      if (ctx.config.backend === "git") {
         const gitLog = await git.log(ctx.root, 1);
         const commitCount = gitLog.ok ? (await git.log(ctx.root, 99999)).output.split("\n").filter(Boolean).length.toString() : "0";
         const remote = await git.hasRemote(ctx.root);
diff --git a/src/commands/sync.ts b/src/commands/sync.ts
index c8f7bb2..3218181 100644
--- a/src/commands/sync.ts
+++ b/src/commands/sync.ts
@@ -1,6 +1,6 @@
 import { Command } from "commander";
 import * as git from "../lib/git.ts";
-import { requireFilesystem } from "../lib/storage.ts";
+import { requireGit } from "../lib/storage.ts";
 import type { WikiContext } from "../types.ts";
 
 export function makeSyncCommand(): Command {
@@ -8,7 +8,7 @@ export function makeSyncCommand(): Command {
     .description("Pull then push (sync with remote)")
     .action(async function (this: Command) {
       const ctx: WikiContext = this.optsWithGlobals().wikiContext;
-      requireFilesystem(ctx, "sync");
+      requireGit(ctx, "sync");
 
       if (!(await git.hasRemote(ctx.root))) {
         console.error('No remote configured. Use "wiki repo connect" to add one.');
diff --git a/src/lib/git-provider.ts b/src/lib/git-provider.ts
new file mode 100644
index 0000000..4eab8f0
--- /dev/null
+++ b/src/lib/git-provider.ts
@@ -0,0 +1,43 @@
+import { WikiManager } from "./wiki.ts";
+import * as git from "./git.ts";
+import type { StorageProvider } from "../types.ts";
+
+export class GitProvider implements StorageProvider {
+  private wiki: WikiManager;
+  public readonly root: string;
+
+  constructor(root: string) {
+    this.root = root;
+    this.wiki = new WikiManager(root);
+  }
+
+  async readPage(relativePath: string): Promise<string | null> {
+    return this.wiki.readPage(relativePath);
+  }
+
+  async writePage(relativePath: string, content: string): Promise<void> {
+    await this.wiki.writePage(relativePath, content);
+    await this.autoCommit(`update ${relativePath}`);
+  }
+
+  async appendPage(relativePath: string, content: string): Promise<boolean> {
+    const ok = await this.wiki.appendPage(relativePath, content);
+    if (ok) {
+      await this.autoCommit(`append to ${relativePath}`);
+    }
+    return ok;
+  }
+
+  async pageExists(relativePath: string): Promise<boolean> {
+    return this.wiki.pageExists(relativePath);
+  }
+
+  async listPages(dir?: string): Promise<string[]> {
+    return this.wiki.listPages(dir);
+  }
+
+  private async autoCommit(message: string): Promise<void> {
+    await git.addAll(this.root);
+    await git.commit(this.root, message);
+  }
+}
diff --git a/src/lib/storage.ts b/src/lib/storage.ts
index 91e0676..24cf3f8 100644
--- a/src/lib/storage.ts
+++ b/src/lib/storage.ts
@@ -1,24 +1,30 @@
 import { WikiManager } from "./wiki.ts";
+import { GitProvider } from "./git-provider.ts";
 import type { BackendType, StorageProvider, WikiContext } from "../types.ts";
 
 export function createProvider(
   backend: BackendType,
   root: string,
 ): StorageProvider {
-  if (backend === "filesystem") return new WikiManager(root);
-  throw new Error(
-    `Unknown storage backend: "${backend}". Supported: filesystem`,
-  );
+  switch (backend) {
+    case "filesystem":
+      return new WikiManager(root);
+    case "git":
+      return new GitProvider(root);
+    case "supabase":
+      throw new Error("Supabase backend not yet implemented.");
+    default:
+      throw new Error(
+        `Unknown storage backend: "${backend}". Supported: filesystem, git`,
+      );
+  }
 }
 
-export function requireFilesystem(
-  ctx: WikiContext,
-  commandName: string,
-): void {
+export function requireGit(ctx: WikiContext, commandName: string): void {
   const backend = ctx.config.backend ?? "filesystem";
-  if (backend !== "filesystem") {
+  if (backend !== "git") {
     console.error(
-      `"wiki ${commandName}" requires filesystem backend. This wiki uses "${backend}".`,
+      `"wiki ${commandName}" requires git backend. This wiki uses "${backend}".`,
     );
     process.exit(1);
   }
diff --git a/src/lib/templates.ts b/src/lib/templates.ts
index 746426a..a701d36 100644
--- a/src/lib/templates.ts
+++ b/src/lib/templates.ts
@@ -1,11 +1,15 @@
-import type { WikiConfig } from "../types.ts";
+import type { WikiConfig, BackendType } from "../types.ts";
 
-export function getDefaultConfig(name: string, domain: string): WikiConfig {
+export function getDefaultConfig(
+  name: string,
+  domain: string,
+  backend: BackendType = "filesystem",
+): WikiConfig {
   return {
     name,
     domain,
     created: new Date().toISOString(),
-    backend: "filesystem" as const,
+    backend,
     paths: {
       raw: "raw",
       wiki: "wiki",
diff --git a/src/types.ts b/src/types.ts
index c1e289e..b93cb9e 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,4 +1,4 @@
-export type BackendType = "filesystem";
+export type BackendType = "filesystem" | "git" | "supabase";
 
 export interface StorageProvider {
   readPage(relativePath: string): Promise<string | null>;
diff --git a/test/commands.test.ts b/test/commands.test.ts
index c41d363..36c0177 100644
--- a/test/commands.test.ts
+++ b/test/commands.test.ts
@@ -32,8 +32,8 @@ async function runWiki(args: string[], input?: string): Promise<{ stdout: string
   return { stdout, stderr, exitCode };
 }
 
-async function initWiki(name = "testwiki"): Promise<void> {
-  const result = await runWiki(["init", wikiDir, "--name", name, "--domain", "test"]);
+async function initWiki(name = "testwiki", backend = "filesystem"): Promise<void> {
+  const result = await runWiki(["init", wikiDir, "--name", name, "--domain", "test", "--backend", backend]);
   if (result.exitCode !== 0) {
     throw new Error(`Init failed: ${result.stderr}`);
   }
@@ -225,33 +225,31 @@ describe("log command", () => {
 
 describe("commit command", () => {
   it("commits changes with provided message", async () => {
-    await initWiki();
-    await runWiki(
-      ["-w", "testwiki", "write", "wiki/concepts/new.md"],
-      "New page content",
-    );
-    const result = await runWiki(["-w", "testwiki", "commit", "Add new concept page"]);
+    await initWiki("testwiki", "git");
+    // Modify a file directly (not via wiki write, which auto-commits)
+    const indexPath = join(wikiDir, "wiki/index.md");
+    const content = await readFile(indexPath, "utf-8");
+    await writeFile(indexPath, content + "\n- [[new-entry]]\n", "utf-8");
+    const result = await runWiki(["-w", "testwiki", "commit", "Add new entry"]);
     expect(result.exitCode).toBe(0);
-    expect(result.stdout).toContain("Add new concept page");
+    expect(result.stdout).toContain("Add new entry");
   });
 
   it("reports nothing to commit when clean", async () => {
-    await initWiki();
+    await initWiki("testwiki", "git");
     const result = await runWiki(["-w", "testwiki", "commit", "Empty commit"]);
     expect(result.stdout).toContain("Nothing to commit");
   });
 
-  it("auto-generates message from last log entry", async () => {
-    await initWiki();
-    await runWiki(["-w", "testwiki", "log", "append", "ingest", "Added attention paper"]);
+  it("auto-commits on wiki write with git backend", async () => {
+    await initWiki("testwiki", "git");
     await runWiki(
       ["-w", "testwiki", "write", "wiki/concepts/attention.md"],
       "Attention content",
     );
-    const result = await runWiki(["-w", "testwiki", "commit"]);
-    expect(result.exitCode).toBe(0);
-    // Should use the log entry message as commit message
-    expect(result.stdout).toContain("Added attention paper");
+    // Page was auto-committed, so manual commit has nothing to do
+    const result = await runWiki(["-w", "testwiki", "commit", "Manual commit"]);
+    expect(result.stdout).toContain("Nothing to commit");
   });
 });
 
@@ -380,29 +378,29 @@ describe("orphans command", () => {
 
 describe("history command", () => {
   it("shows git history for a page", async () => {
-    await initWiki();
+    await initWiki("testwiki", "git");
+    // wiki write auto-commits with git backend
     await runWiki(
       ["-w", "testwiki", "write", "wiki/concepts/tracked.md"],
       "Version 1",
     );
-    await runWiki(["-w", "testwiki", "commit", "Add tracked page"]);
     const result = await runWiki(["-w", "testwiki", "history", "wiki/concepts/tracked.md"]);
     expect(result.exitCode).toBe(0);
-    expect(result.stdout).toContain("Add tracked page");
+    expect(result.stdout).toContain("update wiki/concepts/tracked.md");
   });
 });
 
 describe("diff command", () => {
   it("shows no changes when working tree is clean", async () => {
-    await initWiki();
+    await initWiki("testwiki", "git");
     const result = await runWiki(["-w", "testwiki", "diff"]);
     expect(result.exitCode).toBe(0);
     expect(result.stdout).toContain("No changes");
   });
 
   it("shows changes to tracked files", async () => {
-    await initWiki();
-    // Modify a tracked file (index.md was committed during init)
+    await initWiki("testwiki", "git");
+    // Modify a tracked file directly (not via wiki write, which auto-commits)
     const indexPath = join(wikiDir, "wiki/index.md");
     const content = await readFile(indexPath, "utf-8");
     await writeFile(indexPath, content + "\n## New Section\n", "utf-8");
diff --git a/test/init.test.ts b/test/init.test.ts
index 62ed457..ad115c9 100644
--- a/test/init.test.ts
+++ b/test/init.test.ts
@@ -282,7 +282,7 @@ describe("templates", () => {
 // --- init integration ---
 
 describe("init command (integration)", () => {
-  it("creates all directories and files", async () => {
+  it("creates all directories and files (filesystem)", async () => {
     const wikiDir = join(testDir, "mywiki");
     const proc = Bun.spawn(
       ["bun", "run", "bin/wiki.ts", "init", wikiDir, "--name", "mywiki", "--domain", "test"],
@@ -309,7 +309,31 @@ describe("init command (integration)", () => {
     expect(await Bun.file(join(wikiDir, "wiki/index.md")).exists()).toBe(true);
     expect(await Bun.file(join(wikiDir, "wiki/log.md")).exists()).toBe(true);
 
-    // Check git
+    // Filesystem backend should NOT have .git
+    let hasGit = true;
+    try { await stat(join(wikiDir, ".git")); } catch { hasGit = false; }
+    expect(hasGit).toBe(false);
+  });
+
+  it("creates git repo with --backend git", async () => {
+    const wikiDir = join(testDir, "gitwiki");
+    const proc = Bun.spawn(
+      ["bun", "run", "bin/wiki.ts", "init", wikiDir, "--name", "gitwiki", "--backend", "git"],
+      {
+        cwd: process.cwd(),
+        stdout: "pipe",
+        stderr: "pipe",
+        env: {
+          ...process.env,
+          GIT_AUTHOR_NAME: "Test",
+          GIT_AUTHOR_EMAIL: "test@test.com",
+          GIT_COMMITTER_NAME: "Test",
+          GIT_COMMITTER_EMAIL: "test@test.com",
+        },
+      },
+    );
+    await proc.exited;
+
     const gitStat = await stat(join(wikiDir, ".git"));
     expect(gitStat.isDirectory()).toBe(true);
   });
diff --git a/test/storage.test.ts b/test/storage.test.ts
index 78e0044..ac63d83 100644
--- a/test/storage.test.ts
+++ b/test/storage.test.ts
@@ -3,6 +3,8 @@ import { mkdtemp, rm } from "fs/promises";
 import { join } from "path";
 import { tmpdir } from "os";
 import { createProvider } from "../src/lib/storage.ts";
+import { GitProvider } from "../src/lib/git-provider.ts";
+import * as git from "../src/lib/git.ts";
 import type { StorageProvider } from "../src/types.ts";
 
 let testDir: string;
@@ -27,6 +29,17 @@ describe("createProvider", () => {
     expect(provider.listPages).toBeInstanceOf(Function);
   });
 
+  it("creates a git provider", () => {
+    const gitProvider = createProvider("git", testDir);
+    expect(gitProvider).toBeInstanceOf(GitProvider);
+  });
+
+  it("throws for supabase (not yet implemented)", () => {
+    expect(() => createProvider("supabase", testDir)).toThrow(
+      "Supabase backend not yet implemented",
+    );
+  });
+
   it("throws for unknown backend", () => {
     expect(() => createProvider("unknown" as any, testDir)).toThrow(
       'Unknown storage backend: "unknown"',
@@ -84,3 +97,56 @@ describe("StorageProvider contract (filesystem)", () => {
     expect(pages).not.toContain("root.md");
   });
 });
+
+describe("GitProvider", () => {
+  let gitDir: string;
+  let gitProvider: StorageProvider;
+
+  beforeEach(async () => {
+    gitDir = await mkdtemp(join(tmpdir(), "llmwiki-git-"));
+    await git.init(gitDir);
+    gitProvider = createProvider("git", gitDir);
+  });
+
+  afterEach(async () => {
+    await rm(gitDir, { recursive: true, force: true });
+  });
+
+  it("writePage stores content and auto-commits", async () => {
+    await gitProvider.writePage("test.md", "hello");
+    const content = await gitProvider.readPage("test.md");
+    expect(content).toBe("hello");
+    const log = await git.log(gitDir, 1);
+    expect(log.ok).toBe(true);
+    expect(log.output).toContain("update test.md");
+  });
+
+  it("appendPage auto-commits on success", async () => {
+    await gitProvider.writePage("page.md", "first\n");
+    await gitProvider.appendPage("page.md", "second");
+    const log = await git.log(gitDir, 2);
+    expect(log.ok).toBe(true);
+    expect(log.output).toContain("append to page.md");
+  });
+
+  it("appendPage does not commit on missing page", async () => {
+    const ok = await gitProvider.appendPage("missing.md", "nope");
+    expect(ok).toBe(false);
+    const log = await git.log(gitDir, 1);
+    // No commits should exist (or only prior ones)
+    expect(log.output).not.toContain("append to missing.md");
+  });
+
+  it("readPage returns null for missing page", async () => {
+    const content = await gitProvider.readPage("nope.md");
+    expect(content).toBeNull();
+  });
+
+  it("listPages works like filesystem", async () => {
+    await gitProvider.writePage("a.md", "a");
+    await gitProvider.writePage("sub/b.md", "b");
+    const pages = await gitProvider.listPages();
+    expect(pages).toContain("a.md");
+    expect(pages).toContain("sub/b.md");
+  });
+});