Core error propagation hardening:

Updated kernel-runner delegate deny path to emit on stderr in packages/bare-os-booter/lib/kernel-runner.js.
Added structured errno metadata (err.code) via vfsErr(...) and applied it to key VFS traversal/permission throws in packages/bare-os-booter/lib/vfs.js (ENOENT/EACCES paths).
Critical command exit-code fixes:

packages/bare-os-coreutils/src/ls.js
Tracks access/stat failures and sets nonzero exit when any operand fails.
packages/bare-os-coreutils/src/grep.js
Recursive walker now reports traversal/stat errors back to main flow so fatal status becomes 2.
packages/bare-os-coreutils/src/rm.js
-f only suppresses not-found style errors; permission/deny failures stay nonzero.
packages/bare-os-coreutils/src/chmod.js
Treats falsy/no-op backend chmod result as failure (nonzero).
packages/bare-os-coreutils/src/find.js
Added root-path preflight so missing root now reports explicit error + nonzero.
Minor quirks:

packages/bare-os-coreutils/src/xargs.js
-P0 now maps to bounded parallel cap (env/default cap), not forced serial.
packages/bare-os-coreutils/src/ulimit.js
-f with value now returns explicit unsupported-setter diagnostic + nonzero.
-f alone reports unlimited.
Regression tests:

Added packages/bare-os-coreutils/test/error-propagation.test.mjs covering:
grep missing file => exit 2
rm -f permission error => nonzero
find missing root => nonzero + diagnostic
ulimit -f 1M => explicit unsupported + nonzero
xargs -P0 bounded behavior

kernel/bin/chmod

@@ -153,7 +153,11 @@ async function run(ctx, argv) {
         }
         perm &= 0o777
       }
-      await ctx.vfs.chmod(f, perm)
+      const r = await ctx.vfs.chmod(f, perm)
+      if (r === false || r == null) {
+        ctx.console.error('chmod: ' + f + ': Operation failed')
+        ctx.exitCode = 1
+      }
     } catch (e) {
       ctx.console.error('chmod: ' + f + ': ' + (e.message || e))
       ctx.exitCode = 1