Pod quota chain runs on CSS-internal /.internal/ writes — full pod walks per chunk and before/after every write — causing WrappedExpiringReadWriteLocker 6s lock expiries on IDP adapter storage and O(chunks × pod) write overhead. #2208

Environment

• Pivot with CSS 7.2.0

Description

• Problem
  With a per-pod quota enabled (config/storage/backend/pod-quota-file.json),
  every write — including writes to CSS-internal storage under /.internal/ —
  goes through the quota chain:

1. QuotaValidator calls getAvailableSpace before and after every write
   and createQuotaGuard mid-stream.
2. Default PodQuotaStrategy.createQuotaGuard calls getAvailableSpace (a
   full pod walk) per stream chunk: chunks × O(pod size).
3. getAvailableSpace does pod discovery (searchPimStorage) + a full
   recursive size walk via FileSizeReporter when the pod isn't cached;
   FileSizeReporter also accumulates large dirent arrays in memory.

• Observed impact (production)
  The IDP KeyValueStorage (AuthorizationCode store at
  /.internal/idp/adapter/) is backed by
  ResourceStore → ResourceStore_Backend → FileDataAccessor, so login writes
  hit the same chain:

  [WrappedExpiringReadWriteLocker] error: Lock expired after 6000ms on
  /.internal/idp/adapter/AuthorizationCode/
  [WrappedExpiringStorage] error: ... Failed to remove expired entries ...

On a sufficiently large pod, any internal write exceeds the 6s lock expiry —
logins and refresh flows fail intermittently.

• Root cause
  ignoreFolders: ["^/\\.internal$"] only excludes .internal from the size
  reporter's walk — it does not stop QuotaValidator from validating
  internal writes. CSS-internal storage shares the user accessor chain with pod
  data.

• Suggested fix
  Exempt /.internal/* at the quota strategy/validator level (return unlimited
  space without pod discovery/walk), not only in the reporter's walk excludes —
  as implemented in solid-contrib/pivot (FastQuotaStrategy.getAvailableSpace
  + delta-accessor skip).