diff --git a/src/cli.ts b/src/cli.ts
index 460d14b..4bcc5a5 100755
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -10,6 +10,7 @@ import { action as reviewAction } from "./commands/review.ts"
 import { action as shellAction } from "./commands/shell.ts"
 import { action as closeAction } from "./commands/close.ts"
 import { action as mergeAction } from "./commands/merge.ts"
+import { action as rebaseAction } from "./commands/rebase.ts"
 import { action as saveAction } from "./commands/save.ts"
 import { action as diffAction } from "./commands/diff.ts"
 import { action as showAction } from "./commands/show.ts"
@@ -96,6 +97,14 @@ program
   .description("Merge a branch into main and close the session")
   .action(mergeAction)
 
+// ── sandlot rebase ───────────────────────────────────────────────────
+
+program
+  .command("rebase")
+  .argument("<branch>", "branch name")
+  .description("Rebase a branch onto the latest main")
+  .action(rebaseAction)
+
 // ── sandlot save ─────────────────────────────────────────────────────
 
 program
diff --git a/src/commands/helpers.ts b/src/commands/helpers.ts
index 9f0d1d5..02de7a8 100644
--- a/src/commands/helpers.ts
+++ b/src/commands/helpers.ts
@@ -1,3 +1,4 @@
+import { join } from "path"
 import { $ } from "bun"
 import * as git from "../git.ts"
 import * as vm from "../vm.ts"
@@ -16,6 +17,30 @@ export async function requireSession(branch: string): Promise<{ root: string; se
   return { root, session }
 }
 
+/** Resolve conflict markers in files using Claude, then stage them. */
+export async function resolveConflicts(
+  files: string[],
+  cwd: string,
+  onFile: (file: string) => void,
+): Promise<void> {
+  for (const file of files) {
+    onFile(file)
+    const content = await Bun.file(join(cwd, file)).text()
+
+    const resolved = await vm.claudePipe(
+      content,
+      "resolve this merge conflict. output ONLY the resolved file content with no markdown fences, no explanation, no surrounding text.",
+    )
+
+    if (resolved.exitCode !== 0) {
+      throw new Error(`Claude failed to resolve ${file}: ${resolved.stderr}`)
+    }
+
+    await Bun.write(join(cwd, file), resolved.stdout.trimEnd() + "\n")
+    await git.stageFile(file, cwd)
+  }
+}
+
 /** Stage all changes, generate a commit message, and commit. Returns true on success. */
 export async function saveChanges(worktree: string, branch: string, message?: string): Promise<boolean> {
   const spin = spinner("Staging changes", branch)
diff --git a/src/commands/merge.ts b/src/commands/merge.ts
index d7a24c1..2561de4 100644
--- a/src/commands/merge.ts
+++ b/src/commands/merge.ts
@@ -1,10 +1,10 @@
-import { join } from "path"
 import * as git from "../git.ts"
 import * as vm from "../vm.ts"
 import * as state from "../state.ts"
 import { spinner } from "../spinner.ts"
 import { die } from "../fmt.ts"
 import { action as closeAction } from "./close.ts"
+import { resolveConflicts } from "./helpers.ts"
 
 export async function action(branch: string) {
   const root = await git.repoRoot()
@@ -28,23 +28,7 @@ export async function action(branch: string) {
 
   try {
     await vm.ensure((msg) => { spin.text = msg })
-
-    for (const file of conflicts) {
-      spin.text = `Resolving ${file}`
-      const content = await Bun.file(join(root, file)).text()
-
-      const resolved = await vm.claudePipe(
-        content,
-        "resolve this merge conflict. output ONLY the resolved file content with no markdown fences, no explanation, no surrounding text.",
-      )
-
-      if (resolved.exitCode !== 0) {
-        throw new Error(`Claude failed to resolve ${file}: ${resolved.stderr}`)
-      }
-
-      await Bun.write(join(root, file), resolved.stdout + "\n")
-      await git.stageFile(file, root)
-    }
+    await resolveConflicts(conflicts, root, (file) => { spin.text = `Resolving ${file}` })
 
     await git.commitMerge(root)
     spin.succeed(`Resolved ${conflicts.length} conflict(s) and merged ${branch}`)
diff --git a/src/commands/rebase.ts b/src/commands/rebase.ts
new file mode 100644
index 0000000..ff7b220
--- /dev/null
+++ b/src/commands/rebase.ts
@@ -0,0 +1,57 @@
+import { $ } from "bun"
+import * as git from "../git.ts"
+import * as vm from "../vm.ts"
+import { spinner } from "../spinner.ts"
+import { die } from "../fmt.ts"
+import { requireSession, resolveConflicts } from "./helpers.ts"
+
+const MAX_REBASE_ROUNDS = 10
+
+export async function action(branch: string) {
+  const { root, session } = await requireSession(branch)
+  const worktree = session.worktree
+
+  if (await git.isDirty(worktree)) {
+    die(`Branch "${branch}" has unsaved changes. Run "sandlot save ${branch}" first.`)
+  }
+
+  const main = await git.mainBranch(root)
+  const fetchSpin = spinner("Fetching origin", branch)
+
+  await $`git -C ${root} fetch origin ${main}`.nothrow().quiet()
+  fetchSpin.text = `Rebasing onto origin/${main}`
+
+  let conflicts = await git.rebase(`origin/${main}`, worktree)
+  if (conflicts.length === 0) {
+    fetchSpin.succeed(`Rebased ${branch} onto ${main}`)
+    return
+  }
+
+  fetchSpin.stop()
+  console.log(`◆ Rebase conflicts in ${conflicts.length} file(s). Resolving with Claude...`)
+  const resolveSpin = spinner("Starting container", branch)
+
+  try {
+    await vm.ensure((msg) => { resolveSpin.text = msg })
+
+    let round = 1
+    while (conflicts.length > 0) {
+      if (round > MAX_REBASE_ROUNDS) {
+        throw new Error(`Exceeded ${MAX_REBASE_ROUNDS} conflict resolution rounds — aborting rebase`)
+      }
+
+      await resolveConflicts(conflicts, worktree, (file) => {
+        resolveSpin.text = `Resolving ${file} (round ${round})`
+      })
+
+      conflicts = await git.rebaseContinue(worktree)
+      round++
+    }
+
+    resolveSpin.succeed(`Rebased ${branch} onto ${main} (resolved ${round - 1} conflict round(s))`)
+  } catch (err) {
+    resolveSpin.fail(String((err as Error).message ?? err))
+    await git.rebaseAbort(worktree)
+    process.exit(1)
+  }
+}
diff --git a/src/git.ts b/src/git.ts
index f7db35a..1f5c475 100644
--- a/src/git.ts
+++ b/src/git.ts
@@ -119,6 +119,43 @@ export async function abortMerge(cwd: string): Promise<void> {
   await $`git merge --abort`.cwd(cwd).nothrow().quiet()
 }
 
+/** Rebase the current branch onto another. Returns conflicted file paths, or empty array if clean. */
+export async function rebase(onto: string, cwd: string): Promise<string[]> {
+  // Bail early if a rebase is already in progress
+  const inProgress = await $`git -C ${cwd} rev-parse --verify --quiet REBASE_HEAD`.nothrow().quiet()
+  if (inProgress.exitCode === 0) {
+    throw new Error(`A rebase is already in progress. Run "git -C ${cwd} rebase --abort" to cancel it first.`)
+  }
+
+  const result = await $`git rebase ${onto}`.cwd(cwd).nothrow().quiet()
+  if (result.exitCode === 0) return []
+
+  const unmerged = await $`git diff --name-only --diff-filter=U`.cwd(cwd).nothrow().quiet().text()
+  const files = unmerged.trim().split("\n").filter(Boolean)
+  if (files.length > 0) return files
+
+  // No conflicts but rebase still failed — include stderr for diagnostics
+  const stderr = result.stderr.toString().trim()
+  throw new Error(`Rebase onto "${onto}" failed: ${stderr || "(no output from git)"}`)
+}
+
+/** Continue a rebase after resolving conflicts. Returns conflicted files for the next commit, or empty if done. */
+export async function rebaseContinue(cwd: string): Promise<string[]> {
+  const result = await $`git -c core.editor=true rebase --continue`.cwd(cwd).nothrow().quiet()
+  if (result.exitCode === 0) return []
+
+  const unmerged = await $`git diff --name-only --diff-filter=U`.cwd(cwd).nothrow().quiet().text()
+  const files = unmerged.trim().split("\n").filter(Boolean)
+  if (files.length > 0) return files
+
+  throw new Error(`Rebase --continue failed: ${result.stderr.toString().trim()}`)
+}
+
+/** Abort an in-progress rebase. */
+export async function rebaseAbort(cwd: string): Promise<void> {
+  await $`git rebase --abort`.cwd(cwd).nothrow().quiet()
+}
+
 /** Check if a worktree has uncommitted changes. */
 export async function isDirty(worktreePath: string): Promise<boolean> {
   const result = await $`git -C ${worktreePath} status --porcelain`.nothrow().quiet()