Tonight's brief was to read everything about "OpenCode API 2.0" and write down what moving to
it would change and what it would buy. Two things fell out of the measuring that are not
migration concerns at all — they are broken in production right now:
The two surfaces are MUTUALLY BLIND. A session created through /api reads as [] on the legacy
GET /session/{id}/message, and a legacy session 500s on GET /api/session/{id}/message. We run
turns through /api since Phase D and read transcripts through legacy, so every opencode
conversation created since 2026-08-10 opens empty — the row carries its title and directory
from the session record, and the transcript underneath it is nothing.
GET /api/session defaults to 50 rows and hands back a cursor.next. We send neither limit nor
cursor, so the oldest sessions silently stop appearing once the store passes 50. The local
store is at exactly 50 today. That is this morning's commit.
On the name: there is no "2.0" in the running server, and "API 2.0" turns out to mean two
different things. The /api/* surface in 1.18.16 has operation ids literally called v2.*, and
we already run every turn on it — so it is not something to adopt, it is something to finish.
OpenCode 2.0 the product is a separate beta (binary opencode2, npm @next) whose docs warn it
may wipe data, and which REMOVES the two durable routes the restart-recovery work would depend
on, in favour of an experimental/ path. Worth knowing before building on them.
Verified by driving a real turn end to end: the durable event log replays from a cursor
(?after=5 returned exactly 6-10, and the SSE at ?after=7 replayed 8,9,10 then held the socket),
which is the answer to the gap Phase B left open. But deltas are live-only BY SCHEMA — the
durable oneOf has 28 members and omits text.delta, tool.input.delta, reasoning.delta,
compaction.delta — so both streams are needed, not one.
Also reproduced a second silent-failure mode with the same signature as the missing credential:
a session with no model, on a serve with no configured default, sits at admitted -> prompted
forever. Our runner only sets a model when one was asked for.
Probes cleaned up after themselves; the session store is back to the 50 rows it started with.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
