Workflow.record: platform-recorded typed history with list/latest

[czpython]

Every extension that accumulates working state hand-maintains a journal — each agent call wrapped in an add_* write, the replay contract restated in a docstring — rebuilding what the platform already witnesses at its own chokepoints. This gives the SDK the record instead.

Workflow.record — an ordered, in-memory, read-only record of the run's typed utterances, appended by the platform:

• Agent.__call__ appends the post-to_result() domain value, body-level only. The existing _in_step gate keeps in-step calls out on the live pass; the enclosing step's memoization keeps them out on replay — so the record rebuilds bit-for-bit on recovery. run() bodies (one whole step) never append.
• Gate.wait appends the validated Gate instance.
• review() now returns a typed ReviewReply (platform-owned Gate subclass, topic pinned to review) and appends it. The resume endpoint's wire shape is untouched — {action, answers, note} validates as-is, partial senders included.

Selection is by contract type, never by producer: record.list(T, **filters) / record.latest(T, **filters), flat attr=value equality, ANDed — subscriber-filter semantics. No after=, no windows, no ordinals — a projection that needs more is a domain bug, per the ticket.

record is a plain read-don't-write instance attribute, same species as subject and input. Two SDK test flows that used the name as a step renamed to note_repo.

Nothing is stored and no DBOS step was added, renamed, or reordered — in-flight runs replay across this deploy unchanged.

Docs: "Replay-rebuilt workflow state" in writing-an-extension.md becomes "The run record" — the platform records the run's calls, extensions project them; step returns and run() internals stay in locals.

Build's _plan_phase moves to attribute access on the typed reply; the journal migration itself is ENG-734, stacked on this.

codex-reviewed: the adversarial pass flagged subclass shadowing of record and a filter-typo inconsistency. The typo behavior is settled as plain subscriber semantics (attributes read directly; a typo raises as entries scan); the shadowing hardening (getter-only property + reserved-name check) was tried and dropped — platform attributes stay plain read-don't-write names here, like subject/input/state.

ENG-733