Add non-Git projects across filesystem mounts (#2187)

* fix(projects): allow non-git folders across mounts

Treat failed Git worktree discovery as non-Git so ordinary directories remain addable. Preserve the underlying diagnostic as a structured warning instead of failing project creation.

* fix(projects): preserve discovery warnings

Propagate checkout context through the remaining worktree discovery calls so fail-open classification retains its structured warning.

packages/server/src/utils/checkout-git.ts

@@ -780,7 +780,7 @@ export interface MergeFromBaseOptions {
 export interface CheckoutContext {
   paseoHome?: string;
   worktreesRoot?: string;
-  logger?: Pick<Logger, "trace">;
+  logger?: Pick<Logger, "trace" | "warn">;
   facts?: CheckoutSnapshotFacts | null;
 }
 
@@ -805,13 +805,6 @@ export type CheckoutSnapshotFacts =
       pullRequestLookupTarget: PullRequestStatusLookupTarget | null;
     };
 
-function isNotGitRepositoryError(error: unknown): boolean {
-  if (!(error instanceof Error)) {
-    return false;
-  }
-  return /not a git repository \(or any of the parent directories\): \.git/i.test(error.message);
-}
-
 async function requireGitRepo(cwd: string): Promise<void> {
   try {
     await runGitCommand(["rev-parse", "--git-dir"], { cwd, envOverlay: READ_ONLY_GIT_ENV });
@@ -867,10 +860,12 @@ async function getWorktreeRoot(cwd: string, context?: CheckoutContext): Promise<
     });
     return parseGitRevParsePath(stdout);
   } catch (error) {
-    if (isNotGitRepositoryError(error)) {
-      return null;
-    }
-    throw error;
+    // Git discovery is fail-open: keep the directory usable as non-Git and retain the diagnostic.
+    context?.logger?.warn(
+      { err: error, cwd },
+      "Git worktree discovery failed; treating directory as non-Git",
+    );
+    return null;
   }
 }
 
@@ -1035,7 +1030,7 @@ async function getPaseoWorktreeForCwd(
 
   return {
     isPaseoOwnedWorktree: true,
-    worktreeRoot: knownWorktreeRoot ?? (await getWorktreeRoot(cwd)) ?? cwd,
+    worktreeRoot: knownWorktreeRoot ?? (await getWorktreeRoot(cwd, context)) ?? cwd,
   };
 }
 
@@ -2972,7 +2967,7 @@ export async function mergeToBase(
   }
   let normalizedBaseRef = baseRef;
   normalizedBaseRef = normalizeLocalBranchRefName(normalizedBaseRef);
-  const currentWorktreeRoot = (await getWorktreeRoot(cwd)) ?? cwd;
+  const currentWorktreeRoot = (await getWorktreeRoot(cwd, context)) ?? cwd;
   if (normalizedBaseRef === currentBranch) {
     return currentWorktreeRoot;
   }