chore(release): bump engine to 0.9.0

[manojp99]

What's new in 0.9.0

The headline: opencode and any OpenAI-compatible client now get full session continuity with zero config. Before 0.9.0, every chat-completions request created a new amplifier session with a random sid; one opencode conversation fragmented into N session dirs. With 0.9.0, the amplifier session_id is derived from the client's session header (sent automatically by Vercel AI SDK), so one opencode conversation = one amplifier session — unified audit trail, persistent hook state across turns, append-mode events.jsonl.

Added

• Chat-completions session resume via X-Client-Session-Id / X-Session-Id. Server now uses a deterministic http-<client_sid> as the amplifier session_id, auto-detects first-turn vs continuation by checking if the session state dir exists on disk, and passes is_resumed to the kernel resume mechanism (same primitive amplifier-agent run --resume uses). One client conversation = one amplifier session. (feat(http): session resume via X-Client-Session-Id; client-authoritative reconciliation #71)

• X-Session-Id header fallback — opencode and other Vercel AI SDK-based clients send this header automatically. amplifier-agent now recognizes it as a fallback for X-Client-Session-Id, so session-resume works out of the box for opencode with zero client config. X-Client-Session-Id (our amplifier-native convention) remains authoritative when both are present. (feat(http): X-Session-Id fallback + drop workspace suffix #72)

• Client-authoritative transcript reconciliation in _reconciler.py. The chat-completions wire is stateless — clients send full history every turn. On divergence between stored and incoming, the client wins by fiat: we persist their view over ours without any rewind ceremony. (feat(http): session resume via X-Client-Session-Id; client-authoritative reconciliation #71)

Changed

• reconcile_client_history now runs foundation's transcript-repair pass before persisting. Catches broken chat-completions clients (orphaned tool_use without paired tool_result, ordering violations, incomplete assistant turns) that would otherwise cause Anthropic to reject the next LLM call with HTTP 400. Mirrors _runtime.py:_repair_loaded_transcript_if_needed from the CLI face. Healthy transcripts pass through unchanged (<10ms diagnostic). (feat(reconciler): repair broken client transcripts before persist #73)

• Workspace name is no longer suffixed with the client session id. Previously, X-Client-Session-Id: abc would route requests into workspaces/<base>-abc/. Now the workspace stays at <base> and per-client distinction is purely at the session_id level (workspaces/<base>/sessions/http-abc/). This keeps workspace-level hook state shared across all sessions of the same server process, where it belongs. (feat(http): X-Session-Id fallback + drop workspace suffix #72)

Wire protocol

Unchanged at 0.3.0. No wrapper bump. TypeScript wrapper stays at 0.7.0.

Backward compatibility

• Clients NOT sending X-Client-Session-Id or X-Session-Id: behavior unchanged — random sid per turn, no resume.
• Clients sending only X-Client-Session-Id: behavior unchanged from PR feat(http): session resume via X-Client-Session-Id; client-authoritative reconciliation #71.
• Clients sending only X-Session-Id (opencode default): NEW — gets full session continuity.
• Clients sending both: X-Client-Session-Id wins.

The wire format (request body, response body, headers) is unchanged. The only observable difference for existing clients is the on-disk workspace dir layout — workspace name is no longer suffixed with the client session id.

See CHANGELOG.md [0.9.0] for full details, including the [0.8.0] section which still applies.