ChatSession.messages flips from list[dict] to list[Turn] — the in-memory
canonical trajectory. Reads migrate to typed fields (turn.role, turn.text,
turn.tool_calls); appends and assignments go through turn_from_dict /
turns_from_dicts; the fork bulk-save and retry's multipart check read via
turn_to_dict. _full_messages lowers Turns→dicts at the wire boundary — the
fold/repair and provider translators still consume dicts until the next slice.
The token-accounting helpers accept a dict or a Turn.
Non-session consumers migrate too: coordinator_idle_observer and eval to typed
fields (mypy-enumerated), and server's last-assistant extractor via turn_to_dict
(an Any-typed call site mypy could not flag). An all-text multipart content
list (the unreadable-attachment placeholder path) now round-trips faithfully
through the adapter (single text block → str, multiple → list).
Tests that inspected session.messages as dicts read it through the
dicts_from_turns / turn_to_dict bridge; those that built it pass dicts through
turns_from_dicts / turn_from_dict. Byte-identical wire harness; full non-live
suite green (7130).
GenerationCancelled extends BaseException, not Exception, so it bypassed
the except handler in _run_initial. The finally block ran but
_extract_last_assistant_content returned "" (response never appended to
messages), and _fire_notify_targets bailed on the empty content guard.
Fixes:
- Catch BaseException (not just Exception) in _run_initial so
GenerationCancelled is handled and the UI state is cleaned up
- Remove the empty-content suppression in _fire_notify_targets —
scheduled tasks should always deliver, even with a fallback message
when no output was captured
Patrick Buckley