fix(server): checkpoints work in Windows workspaces with paths over 260 characters

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

@@ -15,6 +15,7 @@ import { ChildProcessSpawner } from "effect/unstable/process";
 import { assert, it } from "@effect/vitest";
 
 import { CheckpointRef, GitCommandError, VcsProcessExitError } from "@t3tools/contracts";
+import { HostProcessPlatform } from "@t3tools/shared/hostProcess";
 import * as ServerConfig from "../config.ts";
 import * as CheckpointStore from "../checkpointing/CheckpointStore.ts";
 import * as ProcessRunner from "../processRunner.ts";
@@ -1116,3 +1117,45 @@ it.effect("GitVcsDriver flushes checkpoint objects and refs to disk before publi
     ),
   );
 });
+
+it.effect.each(["win32", "linux"] as const)(
+  "checkpoint working-tree commands enable Git long paths only on Windows (%s)",
+  (platform) =>
+    Effect.gen(function* () {
+      const fs = yield* FileSystem.FileSystem;
+      const path = yield* Path.Path;
+      const liveProcess = yield* VcsProcess.VcsProcess;
+      const driver = yield* GitVcsDriver.makeVcsDriverShape();
+      const cwd = yield* fs.makeTempDirectoryScoped({ prefix: "t3-checkpoint-long-paths-" });
+      const { git, checkpointRef } = yield* makeCheckpointFixture(driver, cwd);
+      // An unborn nested repository fails the first `add`, so recovery's listing runs too.
+      yield* git(["init", "empty"]);
+      const observedArgs: ReadonlyArray<string>[] = [];
+      const platformDriver = yield* GitVcsDriver.makeVcsDriverShape().pipe(
+        Effect.provideService(HostProcessPlatform, platform),
+        Effect.provideService(VcsProcess.VcsProcess, {
+          run: (input) => {
+            observedArgs.push(input.args);
+            return liveProcess.run(input);
+          },
+        }),
+      );
+
+      yield* platformDriver.checkpoints.captureCheckpoint({ cwd, checkpointRef });
+      yield* fs.writeFileString(path.join(cwd, "file.txt"), "changed\n");
+      assert.isTrue(yield* platformDriver.checkpoints.restoreCheckpoint({ cwd, checkpointRef }));
+
+      assert.strictEqual(yield* fs.readFileString(path.join(cwd, "file.txt")), "unstaged\n");
+      assert.strictEqual((yield* git(["ls-tree", checkpointRef, "--", "empty"])).stdout, "");
+      const worktreeCommands = observedArgs.filter((args) =>
+        ["add", "--others", "restore", "clean", "reset"].some((command) => args.includes(command)),
+      );
+      // Failed add, recovery listing, retried add, then restore, clean and reset.
+      assert.strictEqual(worktreeCommands.length, 6);
+      for (const args of worktreeCommands) {
+        const setting = args.indexOf("core.longpaths=true");
+        if (platform === "win32") assert.strictEqual(args[setting - 1], "-c", args.join(" "));
+        else assert.strictEqual(setting, -1, args.join(" "));
+      }
+    }).pipe(Effect.scoped, Effect.provide(GitContractLayer)),
+);

apps/server/src/vcs/GitVcsDriver.ts

@@ -32,6 +32,7 @@ import {
   type VcsStatusResult,
   type WorktreeSubmodules,
 } from "@t3tools/contracts";
+import { HostProcessPlatform } from "@t3tools/shared/hostProcess";
 import {
   makeGitVcsDriverCore,
   PATCH_RENDER_PREFIX_ARGS,
@@ -775,6 +776,13 @@ export const makeVcsDriverShape = Effect.fn("makeGitVcsDriverShape")(function* (
     "core.fsyncMethod=fsync",
   ] as const;
 
+  // Git for Windows cannot open paths longer than MAX_PATH (260 characters) unless
+  // core.longpaths is on, and it is off by default. Without it, checkpoint `git add -A` exits
+  // 128 with "Filename too long" in any workspace holding such a path, and restore cannot write
+  // or clean those files. Checkpoints only snapshot and restore paths that already exist, so
+  // commands that touch the working tree turn it on even if the user's config says false.
+  const longPaths = (yield* HostProcessPlatform) === "win32" ? ["-c", "core.longpaths=true"] : [];
+
   const checkpoints: VcsDriver.VcsCheckpointOps = {
     captureCheckpoint: Effect.fn("GitVcsDriver.checkpoints.captureCheckpoint")(function* (input) {
       const operation = VcsProcess.CHECKPOINT_CAPTURE_OPERATION;
@@ -939,6 +947,7 @@ export const makeVcsDriverShape = Effect.fn("makeGitVcsDriverShape")(function* (
             args: [
               ...indexConfig,
               ...durableWrite,
+              ...longPaths,
               "add",
               ...(sparseCheckout ? ["--sparse"] : []),
               "-A",
@@ -957,7 +966,15 @@ export const makeVcsDriverShape = Effect.fn("makeGitVcsDriverShape")(function* (
                 const untracked = yield* execute({
                   operation,
                   cwd: input.cwd,
-                  args: ["ls-files", "--others", "--exclude-standard", "-z", "--", "."],
+                  args: [
+                    ...longPaths,
+                    "ls-files",
+                    "--others",
+                    "--exclude-standard",
+                    "-z",
+                    "--",
+                    ".",
+                  ],
                   env: commitEnv,
                   maxOutputBytes: WORKSPACE_FILES_MAX_OUTPUT_BYTES,
                 });
@@ -1072,7 +1089,16 @@ export const makeVcsDriverShape = Effect.fn("makeGitVcsDriverShape")(function* (
         yield* execute({
           operation,
           cwd: input.cwd,
-          args: ["restore", "--source", commitOid, "--worktree", "--staged", "--", "."],
+          args: [
+            ...longPaths,
+            "restore",
+            "--source",
+            commitOid,
+            "--worktree",
+            "--staged",
+            "--",
+            ".",
+          ],
         });
       }
       // Restoring away the last tracked file can remove a nested workspace directory.
@@ -1091,7 +1117,7 @@ export const makeVcsDriverShape = Effect.fn("makeGitVcsDriverShape")(function* (
       const cleaned = yield* execute({
         operation,
         cwd: input.cwd,
-        args: ["clean", "-fd", "--", "."],
+        args: [...longPaths, "clean", "-fd", "--", "."],
         allowNonZeroExit: true,
       });
       if (cleaned.exitCode !== 0) {
@@ -1118,7 +1144,7 @@ export const makeVcsDriverShape = Effect.fn("makeGitVcsDriverShape")(function* (
         yield* execute({
           operation,
           cwd: input.cwd,
-          args: ["reset", "--quiet", "--", "."],
+          args: [...longPaths, "reset", "--quiet", "--", "."],
         });
       }