Handle truncated git review diff previews safely

- Drop unterminated paths from truncated NUL-separated git stdout
- Preserve truncation state when building untracked review diffs

Author: juliusmarminge

apps/server/src/vcs/GitVcsDriverCore.test.ts

@@ -9,6 +9,7 @@ import * as Scope from "effect/Scope";
 
 import { GitCommandError } from "@t3tools/contracts";
 import { ServerConfig } from "../config.ts";
+import { splitNullSeparatedGitStdoutPaths } from "./GitVcsDriverCore.ts";
 import * as GitVcsDriver from "./GitVcsDriver.ts";
 
 const ServerConfigLayer = ServerConfig.layerTest(process.cwd(), {
@@ -77,6 +78,30 @@ const initRepoWithCommit = (
   });
 
 it.layer(TestLayer)("GitVcsDriver core integration", (it) => {
+  describe("review diff previews", () => {
+    it.effect("drops an unterminated path from truncated NUL-separated git output", () =>
+      Effect.sync(() => {
+        const paths = splitNullSeparatedGitStdoutPaths({
+          stdout: "complete.txt\0partial",
+          stdoutTruncated: true,
+        });
+
+        assert.deepStrictEqual(paths, ["complete.txt"]);
+      }),
+    );
+
+    it.effect("keeps the final path when NUL-separated git output is complete", () =>
+      Effect.sync(() => {
+        const paths = splitNullSeparatedGitStdoutPaths({
+          stdout: "complete.txt\0final.txt",
+          stdoutTruncated: false,
+        });
+
+        assert.deepStrictEqual(paths, ["complete.txt", "final.txt"]);
+      }),
+    );
+  });
+
   describe("repository status", () => {
     it.effect("reports non-repository directories without failing", () =>
       Effect.gen(function* () {

apps/server/src/vcs/GitVcsDriverCore.ts

@@ -208,6 +208,12 @@ function splitNullSeparatedPaths(input: string, truncated: boolean): string[] {
   return parts.filter((value) => value.length > 0);
 }
 
+export function splitNullSeparatedGitStdoutPaths(
+  result: Pick<GitVcsDriver.ExecuteGitResult, "stdout" | "stdoutTruncated">,
+): string[] {
+  return splitNullSeparatedPaths(result.stdout, result.stdoutTruncated);
+}
+
 function sanitizeRemoteName(value: string): string {
   const sanitized = value
     .trim()
@@ -1654,7 +1660,7 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
   });
 
   const readUntrackedReviewDiffs = Effect.fn("readUntrackedReviewDiffs")(function* (cwd: string) {
-    const untrackedOutput = yield* runGitStdoutWithOptions(
+    const untrackedResult = yield* executeGit(
       "GitVcsDriver.readUntrackedReviewDiffs.list",
       cwd,
       ["ls-files", "--others", "--exclude-standard", "-z"],
@@ -1663,9 +1669,9 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
         truncateOutputAtMaxBytes: true,
       },
     );
-    const untrackedPaths = splitNullSeparatedPaths(untrackedOutput, false);
+    const untrackedPaths = splitNullSeparatedGitStdoutPaths(untrackedResult);
     if (untrackedPaths.length === 0) {
-      return { diff: "", truncated: false };
+      return { diff: "", truncated: untrackedResult.stdoutTruncated };
     }
 
     const diffs = yield* Effect.forEach(
@@ -1689,7 +1695,7 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
         .map((result) => result.stdout)
         .filter((diff) => diff.trim().length > 0)
         .join("\n"),
-      truncated: diffs.some((result) => result.stdoutTruncated),
+      truncated: untrackedResult.stdoutTruncated || diffs.some((result) => result.stdoutTruncated),
     };
   });