β.2 — Vendor + pin opencode in the VSIX

[jack-champagne]

Phase: β — Schuster demo · Plan task: β.2 · Est: 2 pd · Suggested role: Dev B

What to build

Stop assuming opencode on $PATH (audit §4 Assumption 4 — currently a bare cp.spawn("opencode")). Commit/bundle a pinned opencode binary in the VSIX (or a download-at-build step pinned to a SHA), gated by a boot-smoke test.

Acceptance criteria

• VSIX ships an opencode binary at a fixed SHA; build fails if it doesn't reach /event SSE 200 against a synthesized project. (S35)
• ServerManager spawns the vendored binary, not a $PATH lookup. (S35)

Blocked by: none
Authoritative refs: plan §2 β.2 · PRD S35

[Rchari1]

Implementation up at #8 (stacked on #7). Pinned opencode v1.17.3 — boot smoke green on first try: GET /event → 200 (text/event-stream) against a synthesized project on darwin-arm64, no LLM creds. Both ACs evidenced in the PR body; CI now boot-smokes both platform binaries (ubuntu + macos-14 matrix) on every PR including future pin bumps.