feat(axi-sdk-js): add OpenCode ambient integration

[kunchenguid]

Intent

The developer wanted to add OpenCode support to the AXI JavaScript SDK’s existing self-installation system, which already handled Claude and Codex. They asked the agent to research OpenCode’s plugin documentation, discuss the design via lavish-axi, then implement an ambient-context-only OpenCode plugin that injects the AXI home view without adding a custom tool. They explicitly allowed using their real OpenCode setup for development/testing and required end-to-end validation before declaring completion. They also wanted confirmation that downstream users would get OpenCode support automatically after upgrading the SDK, while preserving Claude and Codex behavior.

What Changed

• Added OpenCode support to the AXI JavaScript SDK self-install hooks through a managed ambient-context plugin that injects the AXI home view.
• Updated hook tests and CLI fixtures so OpenCode, Claude, and Codex installation paths are covered without requiring prebuilt dist/ output.
• Refreshed SDK, AXI skill, README, and docs guidance to describe OpenCode plugin-based ambient integration alongside existing session-hook integrations.

Risk Assessment

⚠️ Medium: The diff is well-contained, but it adds a generated global OpenCode plugin that depends on OpenCode's experimental system-transform hook and user runtime environment, so integration risk remains despite no substantiated code findings.

Testing

• Summary: Exercised the axi-sdk-js unit and subprocess integration tests covering hook installation, OpenCode plugin generation/runtime behavior, and the dist-free CLI fixture; all relevant tests passed.
• npm test in packages/axi-sdk-js
• npm test
• npx vitest run test/hooks.test.ts
• npx vitest run test/cli.test.ts -t "hooks automatically|hook installation"
• Outcome: 🔧 1 issue found → auto-fixed across 2 runs (7m49s)

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

Round 1 - passed ✅

✅ **Rebase** - passed

Round 1 - passed ✅

⚠️ **Review** - medium risk

Round 1 - passed ✅

🔧 **Test** - 1 issue found → auto-fixed

Round 1 - found 1 warning

• ⚠️ packages/axi-sdk-js/test/fixtures/version-bin.mjs:1 - npm test fails in the subprocess integration tests because this fixture imports ../../dist/cli.js, but dist/ is not present in the fresh worktree after dependency installation. The focused OpenCode and hook-installation tests run successfully without the prebuilt package output.
• npm test
• npx vitest run test/hooks.test.ts
• npx vitest run test/cli.test.ts -t "hooks automatically|hook installation"

Round 2 (auto-fix) - passed ✅

• npm test in packages/axi-sdk-js

🔧 **Document** - 4 issues found → auto-fixed

Round 1 - found 4 issues (2 warnings, 2 infos)

• ⚠️ .agents/skills/axi/SKILL.md:154 - The AXI skill still says default ambient-context app targets are Claude Code and Codex only. The SDK change now self-installs OpenCode support by default too, so this guidance should include OpenCode to avoid agents building new AXIs from stale target-app assumptions.
• ⚠️ .agents/skills/axi/SKILL.md:163 - The per-app integration guidance lists Claude Code and Codex but has no OpenCode entry. It should document that OpenCode is supported via a managed plugin in ~/.config/opencode/plugins/ using ambient system-context injection rather than a native SessionStart hook.
• ℹ️ README.md:77 - The public principle summary describes ambient context only as self-installing into session hooks. With OpenCode support, the implementation can self-install through a plugin instead, so the summary should be broadened to mention session hooks or plugins/context integrations.
• ℹ️ docs/index.html:578 - The website's Ambient context section says the agent context always comes from session hooks that output to stdout. The new OpenCode path injects the AXI home view through a managed plugin system-context transform, so this public documentation should be updated to avoid excluding the OpenCode behavior.

Round 2 (auto-fix) - passed ✅

🔧 **Lint** - 4 issues found → auto-fixed

Round 1 - found 4 warnings

• ⚠️ docs/index.html:1 - Prettier formatting check failed for this changed file.
• ⚠️ packages/axi-sdk-js/README.md:1 - Prettier formatting check failed for this changed file.
• ⚠️ packages/axi-sdk-js/src/hooks.ts:1 - Prettier formatting check failed for this changed file.
• ⚠️ packages/axi-sdk-js/test/hooks.test.ts:1 - Prettier formatting check failed for this changed file.

Round 2 (auto-fix) - passed ✅

✅ **Push** - passed

Round 1 - passed ✅