DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.
The tengu_sm_compact session memory compaction system, which automatically truncated conversation history using a token-counting approach, has been removed. It is replaced by the new reactive compaction system (see In Development section).
Evidence
Removed orchestrator (search for "tengu_sm_compact" returns 0 results in new version)
Strings lifted out of the shipped bundle, so the claim above can be checked against them.