New section 14: streamAssistant and the three-phase tool execution
blocks (prepare/execute/finalize) with durability callbacks, batch rules
(parallel vs sequential, length truncation, terminate), and the
unbreakable agent-loop.ts compatibility requirement with acceptance
criterion. Harness internals rewritten on top of the blocks: runToolBatch
with provisioned-id callbacks, reconciliation via phases 2+3, hook-to-
block wiring table. Auth surface removed from the stream block: Models
resolves auth per request; before_payload/after_response mount on
onPayload/onResponse. Sections 16-22 renumbered.
Restructured rewrite: concepts (session = tree + lanes + per-lane
operation logs + global facts), records and crash-site traces, recovery
as reduction, then API and implementation top-down. Renames refs to
lanes, generations to tasks; retires leaf entries, de-trees labels and
name, adds deferred provider requests (stopReason deferred, optional
fetchDeferred/cancelDeferred on ProviderStreams, deliberate lane
suspension), SQLite branch cache with tips and reverse lookup, Unix ms
timestamps. Supersedes harness.md.
