diff --git a/scripts/committer b/scripts/committer
index 741e62bb2f2..e11a20d8624 100755
--- a/scripts/committer
+++ b/scripts/committer
@@ -39,7 +39,47 @@ if [ "$#" -eq 0 ]; then
   usage
 fi
 
-files=("$@")
+path_exists_or_tracked() {
+  local candidate=$1
+  [ -e "$candidate" ] || git ls-files --error-unmatch -- "$candidate" >/dev/null 2>&1
+}
+
+append_normalized_file_arg() {
+  local raw=$1
+
+  if path_exists_or_tracked "$raw"; then
+    files+=("$raw")
+    return
+  fi
+
+  if [[ "$raw" == *$'\n'* || "$raw" == *$'\r'* ]]; then
+    local normalized=${raw//$'\r'/}
+    while IFS= read -r line; do
+      if [[ "$line" == *[![:space:]]* ]]; then
+        files+=("$line")
+      fi
+    done <<< "$normalized"
+    return
+  fi
+
+  if [[ "$raw" == *[[:space:]]* ]]; then
+    local split_paths=()
+    # Intentional IFS split for callers that pass a single shell-expanded path blob.
+    # shellcheck disable=SC2206
+    split_paths=($raw)
+    if [ "${#split_paths[@]}" -gt 1 ]; then
+      files+=("${split_paths[@]}")
+      return
+    fi
+  fi
+
+  files+=("$raw")
+}
+
+files=()
+for raw_arg in "$@"; do
+  append_normalized_file_arg "$raw_arg"
+done
 
 # Disallow "." because it stages the entire repository and defeats the helper's safety guardrails.
 for file in "${files[@]}"; do
@@ -129,11 +169,9 @@ run_git_with_lock_retry() {
 }
 
 for file in "${files[@]}"; do
-  if [ ! -e "$file" ]; then
-    if ! git ls-files --error-unmatch -- "$file" >/dev/null 2>&1; then
-      printf 'Error: file not found: %s\n' "$file" >&2
-      exit 1
-    fi
+  if ! path_exists_or_tracked "$file"; then
+    printf 'Error: file not found: %s\n' "$file" >&2
+    exit 1
   fi
 done
 
diff --git a/test/scripts/committer.test.ts b/test/scripts/committer.test.ts
new file mode 100644
index 00000000000..623cd2e09e6
--- /dev/null
+++ b/test/scripts/committer.test.ts
@@ -0,0 +1,89 @@
+import { execFileSync } from "node:child_process";
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import path from "node:path";
+import { afterEach, describe, expect, it } from "vitest";
+
+const scriptPath = path.join(process.cwd(), "scripts", "committer");
+const tempRepos: string[] = [];
+
+function run(cwd: string, command: string, args: string[]) {
+  return execFileSync(command, args, {
+    cwd,
+    encoding: "utf8",
+  }).trim();
+}
+
+function git(cwd: string, ...args: string[]) {
+  return run(cwd, "git", args);
+}
+
+function createRepo() {
+  const repo = mkdtempSync(path.join(tmpdir(), "committer-test-"));
+  tempRepos.push(repo);
+
+  git(repo, "init", "-q");
+  git(repo, "config", "user.email", "test@example.com");
+  git(repo, "config", "user.name", "Test User");
+  writeFileSync(path.join(repo, "seed.txt"), "seed\n");
+  git(repo, "add", "seed.txt");
+  git(repo, "commit", "-qm", "seed");
+
+  return repo;
+}
+
+function writeRepoFile(repo: string, relativePath: string, contents: string) {
+  const fullPath = path.join(repo, relativePath);
+  mkdirSync(path.dirname(fullPath), { recursive: true });
+  writeFileSync(fullPath, contents);
+}
+
+function commitWithHelper(repo: string, commitMessage: string, ...args: string[]) {
+  return run(repo, "bash", [scriptPath, commitMessage, ...args]);
+}
+
+function committedPaths(repo: string) {
+  const output = git(repo, "diff-tree", "--no-commit-id", "--name-only", "-r", "HEAD");
+  return output.split("\n").filter(Boolean).toSorted();
+}
+
+afterEach(() => {
+  while (tempRepos.length > 0) {
+    const repo = tempRepos.pop();
+    if (repo) {
+      rmSync(repo, { force: true, recursive: true });
+    }
+  }
+});
+
+describe("scripts/committer", () => {
+  it("keeps plain argv paths working", () => {
+    const repo = createRepo();
+    writeRepoFile(repo, "alpha.txt", "alpha\n");
+    writeRepoFile(repo, "nested/file with spaces.txt", "beta\n");
+
+    commitWithHelper(repo, "test: plain argv", "alpha.txt", "nested/file with spaces.txt");
+
+    expect(committedPaths(repo)).toEqual(["alpha.txt", "nested/file with spaces.txt"]);
+  });
+
+  it("accepts a single space-delimited path blob", () => {
+    const repo = createRepo();
+    writeRepoFile(repo, "alpha.txt", "alpha\n");
+    writeRepoFile(repo, "beta.txt", "beta\n");
+
+    commitWithHelper(repo, "test: space blob", "alpha.txt beta.txt");
+
+    expect(committedPaths(repo)).toEqual(["alpha.txt", "beta.txt"]);
+  });
+
+  it("accepts a single newline-delimited path blob", () => {
+    const repo = createRepo();
+    writeRepoFile(repo, "alpha.txt", "alpha\n");
+    writeRepoFile(repo, "nested/file with spaces.txt", "beta\n");
+
+    commitWithHelper(repo, "test: newline blob", "alpha.txt\nnested/file with spaces.txt");
+
+    expect(committedPaths(repo)).toEqual(["alpha.txt", "nested/file with spaces.txt"]);
+  });
+});