feat: add OpenCode as a first-class harness client

[Ram-Pavith]

Summary

Adds OpenCode as a first-class CodeAlmanac harness client so build / ingest / garden run through the OpenCode CLI (opencode run), alongside Codex and Claude via Yoke.

Also covers transcript sync, setup UI polish, and almanac wiki — while keeping a native OpenCode harness (not Yoke).

Closes #41

Why not Yoke for OpenCode

OpenCode is a model router, not a single provider. Users already connect OpenRouter, native provider APIs, Zen free models, and other OpenAI-compatible endpoints in the OpenCode TUI. Whatever shows up in opencode models is what they can run interactively.

A Yoke OpenCode path would:

1. Block shipping on AlmanacCode/Yoke releasing and pinning Provider.OPENCODE.
2. Cap model choice to whatever Yoke/CodeAlmanac encodes — always behind the user’s live OpenCode catalog (including nested OpenRouter ids like openrouter/...).
3. Re-own auth that OpenCode already handles.

This PR calls opencode run --model <provider/model> with the user’s normal OpenCode install. Config only checks id shape (provider/model; nested segments allowed). Setup prefers the live opencode models list. Result: lifecycle jobs can use the same connected models as the OpenCode TUI (OpenRouter and everything else OpenCode is logged into), without a second allowlist or Yoke pin.

Contrast: #28 wires OpenCode through Yoke — better if the product wants every harness only via Yoke; worse for “use my OpenCode accounts/models now.”

What changed

Harness

• Native OpenCode adapter (integrations/harnesses/opencode/)
• Lifecycle agents staged under runtime_root/opencode/ via additive OPENCODE_CONFIG_DIR (not the user repo’s .opencode/)
• Setup target + OpenCode provider/model config validation + README

Transcript sync

• TranscriptApp.OPENCODE
• Discovery via ~/.local/share/opencode/opencode.db (session / parent_id IS NULL)
• Synthetic identity opencode-session:<id>
• Runtime over message/part (before generic transcript runtime)
• query_readonly_or_empty for foreign SQLite
• sync --from defaults to all transcript apps

Setup UI polish

• OpenCode brand color, responsive card grid, change-handling module
• SIGWINCH redraw; OpenCode in instruction-step copy
• Telemetry step kept (7-step wizard)

Almanac wiki

• opencode-harness.md, dual on-ramp guide, controlled-model decision carve-out for OpenCode, event-shape/sync docs

Test plan

• uv run pytest tests/test_opencode_*.py tests/test_setup_wizard_*.py tests/test_cli.py -q
• Full uv run pytest / uv run ruff check .
• Manual: config set harness.default opencode + harness.model to an OpenRouter id from opencode models
• Manual: codealmanac sync status --from opencode

Related

• Yoke-based counterpart: feat: wire OpenCode as a third harness via Yoke #28
• Implements Add OpenCode as a first-class CodeAlmanac harness client #41