feat(aircoding): AirCoding V2 baseline — deterministic multi-agent architecture

Forked from OpenCode v1.17.4 with multi-agent system:
- 5 agents: aircoding, scheduler, worker, architect, reviewer
- Deterministic DAG scheduling engine (coordinator_tick)
- Tool whitelists as hard enforcement
- AirCoding validation plugin
- System prompt injection for routing
- V1 requirements: C4 docs, ADR, AGENTS.md, debug-log.md
- Design documents in docs/

packages/core/src/config/plugin/skill.ts

@@ -0,0 +1,48 @@
+export * as ConfigSkillPlugin from "./skill"
+
+import path from "path"
+import { Effect } from "effect"
+import { Config } from "../../config"
+import { Global } from "../../global"
+import { Location } from "../../location"
+import { PluginV2 } from "../../plugin"
+import { AbsolutePath } from "../../schema"
+import { SkillV2 } from "../../skill"
+
+export const Plugin = PluginV2.define({
+  id: PluginV2.ID.make("config-skill"),
+  effect: Effect.gen(function* () {
+    const config = yield* Config.Service
+    const global = yield* Global.Service
+    const location = yield* Location.Service
+    const skill = yield* SkillV2.Service
+    const transform = yield* skill.transform()
+    const entries = yield* config.entries()
+    const directories = entries.flatMap((entry) => (entry.type === "directory" ? [entry.path] : []))
+    const items = entries.flatMap((entry) => (entry.type === "document" ? (entry.info.skills ?? []) : []))
+
+    yield* transform((editor) => {
+      for (const directory of directories) {
+        editor.source(
+          new SkillV2.DirectorySource({ type: "directory", path: AbsolutePath.make(path.join(directory, "skill")) }),
+        )
+        editor.source(
+          new SkillV2.DirectorySource({ type: "directory", path: AbsolutePath.make(path.join(directory, "skills")) }),
+        )
+      }
+      for (const item of items) {
+        if (URL.canParse(item) && /^(https?:)$/.test(new URL(item).protocol)) {
+          editor.source(new SkillV2.UrlSource({ type: "url", url: item }))
+          continue
+        }
+        const expanded = item.startsWith("~/") ? path.join(global.home, item.slice(2)) : item
+        editor.source(
+          new SkillV2.DirectorySource({
+            type: "directory",
+            path: AbsolutePath.make(path.isAbsolute(expanded) ? expanded : path.join(location.directory, expanded)),
+          }),
+        )
+      }
+    })
+  }),
+})