Two-tier memory subsystem — short-term working storage, long-term pattern lookup, and security

Failure modes

Symptom	Cause	Fix	Severity
`TypeError: __init__() missing 1 required positional argument: 'user_id'`	`UnifiedMemory()` constructed without `user_id`	Pass `user_id` — it is required	high
`persist_pattern` / `stage_pattern` returns `None`	Long-term storage unavailable (e.g. no writable `storage_dir`)	Check `health_check()` / `get_backend_status()`; confirm storage config	medium
`retrieve` returns `None` for a key you stashed	The entry expired (`ttl_seconds`) or the backend isn't persistent	Re-stash with a longer TTL; check `supports_persistence()`	medium
Cross-process reads don't see another process's writes	The backend isn't distributed (in-process store)	Check `supports_distributed()`; configure Redis	medium
`recall_pattern` returns `None` for a real id	`check_permissions=True` and the caller's `access_tier` is insufficient	Use a higher `access_tier`, or pass `check_permissions=False` for trusted callers	medium
A `SENSITIVE` pattern stored unencrypted	`encryption_enabled` is off in the config	Enable encryption in `MemoryConfig`	medium

user_id is required. UnifiedMemory is per-user; there is no zero-arg constructor.
Protocol vs. UnifiedMemory signatures differ. The protocol's stash(key, value, ttl, agent_id) is not UnifiedMemory's stash(key, value, ttl_seconds) — don't conflate them.
Capabilities are deployment-dependent. Real-time, distribution, and persistence vary by backend — check before relying on them.

Confirm construction: UnifiedMemory(user_id="...").
health_check() / get_backend_status() for backend state.
get_capabilities() to confirm realtime/distributed/persistence.
For a missing short-term key, check the TTL and supports_persistence().
For a missing pattern, check pattern_id, access_tier, and check_permissions.