Centralize shared fields

When multiple modules need the same state/config/schema (e.g., context variables like timezone, or prompt search paths), do not replicate those fields or the logic that derives them in several places. Instead, funnel access through a single abstraction and reuse shared utilities.

How to apply:

• Single source of truth: If snapshot/state is the canonical model, expose typed getters/builders (or pass around the snapshot-derived object) so handlers/schedulers don’t individually parse/maintain each field.
• Centralize composition logic: Put “include plugins” (or similar discovery rules) into one shared helper (e.g., subagents.get_paths(..., include_plugins=True)) instead of building paths in multiple call sites.
• Small readability refactors: Prefer extracting complex expressions/branches into named variables for clarity (especially around error handling/cleanup).

Example (pattern):

# Instead of each module reading/handling timezone separately,
# make snapshot the source of truth.

# snapshot.py
@dataclass
class SnapshotContext:
    timezone: str
    # ...other shared fields

def build_context_from_snapshot(snapshot: Any) -> SnapshotContext:
    return SnapshotContext(timezone=snapshot.timezone)

# state_sync_handler.py
ctx = build_context_from_snapshot(snapshot)
state_monitor.mark_dirty(sid, reason=reason, timezone=ctx.timezone)

# Or, if StateMonitor only stores projection fields,
# accept an object built from snapshot rather than individual scalars.

This reduces “adjust multiple scripts when fields change” and keeps code organization consistent while improving readability.