Export OpenCode plugin module with id so the UI shows its name

[svarlamov-git-ai]

Fixes #2153

Problem

The OpenCode plugin only exported a plain plugin function (what OpenCode now calls the legacy format), so OpenCode had no id to display and fell back to showing the plugin as file:///.../.config/opencode/plugins/git-ai.ts in its UI.

Why not the v2 plugin API

The issue suggests migrating to define({ id, setup }) from @opencode-ai/plugin/v2/promise. I verified against OpenCode's source that the shipped v2 plugin context only exposes domain transforms (agent, catalog, command, integration, reference, skill) and aisdk hooks — it has no tool.execute.before/after hooks. Those are only on OpenCode's v2 roadmap (packages/plugin/src/v2/effect/PLAN.md, "Migrate Runtime Hooks → Tool execution hooks"). A pure v2 plugin would therefore lose all checkpointing, which is the plugin's entire purpose.

Fix

Use OpenCode's supported module format instead, which is exactly where its loader reads a plugin's display name from (resolvePluginId/readPluginId in packages/opencode/src/plugin/shared.ts — file-based plugins are expected to export an id):

const GitAiPluginModule: PluginModule = {
  id: "git-ai",
  server: GitAiPlugin,
}

export default GitAiPluginModule

The named GitAiPlugin export is kept for backwards compatibility: OpenCode versions predating the module format iterate a plugin module's exports and call each one as a function, and module namespace ordering puts GitAiPlugin before default, so the plugin still registers there. Current OpenCode detects the default-exported module, uses its id, and registers server() exactly once (no double registration; verified the loader history — server-object unwrapping and module detection shipped together).

The plugin typechecks cleanly against the latest published @opencode-ai/plugin package (tsc --strict). The import type is erased at runtime, so older installed type packages without PluginModule are unaffected.

Related: #2162

Investigated whether git-ai drops .md files from AI stats: it does not — default stats ignore patterns have no Markdown entries, and the OpenCode preset does no extension filtering. Added an integration test (test_opencode_new_markdown_file_gets_ai_attribution) proving a new skill.md written through OpenCode's write tool hooks gets full AI attribution. While writing it, found the test blame helper's AI_AUTHOR_NAMES didn't recognize opencode as an AI author; fixed. If #2162 reproduces for the reporter, a plugin that failed to load/display correctly (this issue) is a plausible cause.

Test coverage

• test_opencode_plugin_default_export_is_module_with_id (new, TDD — failed before the fix): asserts the module default export with id: "git-ai" and the retained named export.
• test_opencode_plugin_content_is_valid_typescript updated for the new imports/default export.
• test_opencode_new_markdown_file_gets_ai_attribution (new): end-to-end OpenCode-preset checkpoint flow on a new .md file, asserting committed line attribution.
• Full test suite, task lint, and task fmt pass.

🤖 Generated with Claude Code

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[devin-ai-integration]

✅ Devin Review: No Issues Found

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