test(runtime): stop implying the folder-workspace escape guard is load-bearing

The two `..` tests both passed with the guard deleted: child repos are already
filtered to those inside the folder root, so any path a match could accept is
inside the folder anyway. Replace the tautological test with one that pins the
real behavior (a `..` path normalizing back inside still routes) and label the
guard as defense-in-depth against the candidate filter widening.

Co-authored-by: Orca <help@stably.ai>

src/main/runtime/folder-workspace-child-repos.test.ts

@@ -54,6 +54,16 @@ describe('matchFolderWorkspaceChildRepo', () => {
     expect(matchFolderWorkspaceChildRepo([API, OUTSIDE], FOLDER, '../other/x.ts')).toBeNull()
   })
 
+  it('routes a `..` path that normalizes back inside the workspace', () => {
+    // Why: normalization, not the escape guard, is what decides this. A path can
+    // only reach a child repo if it is already inside the folder, since child repos
+    // are filtered to the folder — so the guard rejects nothing a match would have
+    // accepted. It stays as defense-in-depth if that filter ever changes.
+    expect(
+      matchFolderWorkspaceChildRepo([API], FOLDER, 'fint_api/../../fint/fint_api/src/app.ts')
+    ).toEqual({ repo: API, rebasedRelativePath: 'src/app.ts' })
+  })
+
   it('returns null for a path in the folder but outside every child repo', () => {
     expect(matchFolderWorkspaceChildRepo([API], FOLDER, 'README.md')).toBeNull()
   })

src/main/runtime/folder-workspace-child-repos.ts

@@ -39,8 +39,10 @@ export function matchFolderWorkspaceChildRepo(
     return null
   }
   const absolutePath = resolveRuntimePath(folderPath, relativePath)
-  // Why: a `..` segment can escape the workspace, which must not silently
-  // resolve to an unrelated repo the user never opened.
+  // Why: a `..` segment must not silently resolve to a repo the user never opened.
+  // Defense-in-depth today — the loop below only considers repos already inside
+  // `folderPath`, so anything it could match is inside the folder anyway. This
+  // stops that from being load-bearing if the candidate filter ever widens.
   if (relativePathInsideRoot(folderPath, absolutePath) === null) {
     return null
   }