fix(server): selected-file commits work through a symlink to a repository subdirectory

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

@@ -4222,6 +4222,11 @@ it.layer(layerTest)("GitVcsDriver core integration", (it) => {
           NodeFS.existsSync(path.join(status.workingTree.rootPath!, "nested", "new.txt")),
           true,
         );
+        // Git prints index and object paths relative to its physical cwd, not this alias.
+        const aliasCwd = path.join(yield* makeTmpDir(), "alias");
+        NodeFS.symlinkSync(nestedCwd, aliasCwd, "junction");
+        const prepared = yield* driver.prepareCommitContext(aliasCwd, ["nested/new.txt"]);
+        assert.include(prepared?.stagedSummary ?? "", "nested/new.txt");
         yield* driver.commit(nestedCwd, "Commit nested selection", "", {
           stage: { filePaths: ["nested/new.txt", "nested/tracked.txt"] },
         });

apps/server/src/vcs/GitVcsDriverCore.ts

@@ -2633,7 +2633,9 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
             cwd,
             ["rev-parse", "--git-path", "index", "--git-path", "objects"],
           )).split("\n");
-          const indexPath = path.resolve(cwd, indexValue.trim());
+          // Git prints these relative to its physical cwd, so resolve them past a symlinked cwd.
+          const physicalCwd = yield* fileSystem.realPath(cwd).pipe(Effect.orElseSucceed(() => cwd));
+          const indexPath = path.resolve(physicalCwd, indexValue.trim());
           const directory = yield* fileSystem.makeTempDirectoryScoped({
             prefix: "t3code-commit-index-",
           });
@@ -2651,7 +2653,7 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
           const quoted = (entry: string) =>
             entry.startsWith('"') ? entry : `"${entry.replace(/[\\"]/g, "\\$&")}"`;
           const alternates = [
-            path.resolve(cwd, objectsValue.trim()),
+            path.resolve(physicalCwd, objectsValue.trim()),
             ...objectDirectories
               .split("\n")
               .flatMap((line) =>