The event-type allowlist and opaque-payload attachment policy change live
Session authorization/export behavior independently of a format upgrade.
They belong in a focused PR against master, where supported native V3 nested
tool-result content must also be handled deliberately.
Restore the session-controller and archive implementation, tests and README
pairs to this layer's parent. Remove the test-only session-format-catalog
dependency and its lock entry with the migration-specific attachment tests.
The original changes are captured from immutable commit 85737364be9 for the
standalone work; migration identifier conversion and reader checks are intact.
This extraction keeps the integration stack's existing attachment behavior
until the separate policy change is reviewed. It makes no Session-format,
schema or version change.
Tianyi Cui
d5302e33f8