core: remove @effect/language-service plugin and optimize hot path type performance

- Removed @effect/language-service from both packages/core and packages/opencode tsconfig files and dependencies

- Wrapped mergeDeep calls in config loading and LLM streaming to avoid expensive remeda conditional merge type instantiations in hot paths

- Narrowed Drizzle migrate() overload signature to avoid expensive variance checks during database initialization

These changes reduce TypeScript type-checking overhead and improve startup and runtime performance for config loading, LLM streaming, and database migrations.

packages/opencode/src/config/config.ts

@@ -3,7 +3,7 @@ import path from "path"
 import { pathToFileURL } from "url"
 import os from "os"
 import z from "zod"
-import { mergeDeep, pipe } from "remeda"
+import { mergeDeep } from "remeda"
 import { Global } from "@opencode-ai/core/global"
 import fsNode from "fs/promises"
 import { NamedError } from "@opencode-ai/core/util/error"
@@ -47,8 +47,13 @@ import { Npm } from "@opencode-ai/core/npm"
 const log = Log.create({ service: "config" })
 
 // Custom merge function that concatenates array fields instead of replacing them
+// Keep remeda's deep conditional merge type out of hot config-loading paths; TS profiling showed it dominates here.
+function mergeConfig(target: Info, source: Info): Info {
+  return mergeDeep(target, source) as Info
+}
+
 function mergeConfigConcatArrays(target: Info, source: Info): Info {
-  const merged = mergeDeep(target, source)
+  const merged = mergeConfig(target, source)
   if (target.instructions && source.instructions) {
     merged.instructions = Array.from(new Set([...target.instructions, ...source.instructions]))
   }
@@ -387,12 +392,10 @@ export const layer = Layer.effect(
     })
 
     const loadGlobal = Effect.fnUntraced(function* () {
-      let result: Info = pipe(
-        {},
-        mergeDeep(yield* loadFile(path.join(Global.Path.config, "config.json"))),
-        mergeDeep(yield* loadFile(path.join(Global.Path.config, "opencode.json"))),
-        mergeDeep(yield* loadFile(path.join(Global.Path.config, "opencode.jsonc"))),
-      )
+      let result: Info = {}
+      result = mergeConfig(result, yield* loadFile(path.join(Global.Path.config, "config.json")))
+      result = mergeConfig(result, yield* loadFile(path.join(Global.Path.config, "opencode.json")))
+      result = mergeConfig(result, yield* loadFile(path.join(Global.Path.config, "opencode.jsonc")))
 
       const legacy = path.join(Global.Path.config, "config")
       if (existsSync(legacy)) {
@@ -402,7 +405,7 @@ export const layer = Layer.effect(
               const { provider, model, ...rest } = mod.default
               if (provider && model) result.model = `${provider}/${model}`
               result["$schema"] = "https://opencode.ai/config.json"
-              result = mergeDeep(result, rest)
+              result = mergeConfig(result, rest)
               await fsNode.writeFile(path.join(Global.Path.config, "config.json"), JSON.stringify(result, null, 2))
               await fsNode.unlink(legacy)
             })