core: consolidate shared infrastructure into core package

Moves effect logging, observability, runtime utilities, flags, installation
version info, and process utilities from opencode to core package. This
enables better code sharing across packages and establishes core as the
single source of truth for foundational utilities.

All internal imports updated to use @opencode-ai/core paths for consistency.

9 files changed, 553 insertions, 16 deletions

diff --git a/packages/core/src/effect/logger.ts b/packages/core/src/effect/logger.ts
new file mode 100644
index 000000000..69f9631e0
--- /dev/null
+++ b/packages/core/src/effect/logger.ts
@@ -0,0 +1,73 @@
+import { Cause, Effect, Logger, References } from "effect"
+import * as Log from "../util/log"
+
+type Fields = Record<string, unknown>
+
+const normalizeKey = (key: string) => (key === "sessionID" ? "session.id" : key)
+
+export interface Handle {
+  readonly debug: (msg?: unknown, extra?: Fields) => Effect.Effect<void>
+  readonly info: (msg?: unknown, extra?: Fields) => Effect.Effect<void>
+  readonly warn: (msg?: unknown, extra?: Fields) => Effect.Effect<void>
+  readonly error: (msg?: unknown, extra?: Fields) => Effect.Effect<void>
+  readonly with: (extra: Fields) => Handle
+}
+
+const clean = (input?: Fields): Fields =>
+  Object.fromEntries(
+    Object.entries(input ?? {})
+      .filter((entry) => entry[1] !== undefined && entry[1] !== null)
+      .map(([key, value]) => [normalizeKey(key), value]),
+  )
+
+const text = (input: unknown): string => {
+  // oxlint-disable-next-line no-base-to-string
+  if (Array.isArray(input)) return input.map((item) => String(item)).join(" ")
+  // oxlint-disable-next-line no-base-to-string
+  return input === undefined ? "" : String(input)
+}
+
+const call = (run: (msg?: unknown) => Effect.Effect<void>, base: Fields, msg?: unknown, extra?: Fields) => {
+  const ann = clean({ ...base, ...extra })
+  const fx = run(msg)
+  return Object.keys(ann).length ? Effect.annotateLogs(fx, ann) : fx
+}
+
+export const logger = Logger.make((opts) => {
+  const extra = clean(opts.fiber.getRef(References.CurrentLogAnnotations))
+  const now = opts.date.getTime()
+  for (const [key, start] of opts.fiber.getRef(References.CurrentLogSpans)) {
+    extra[`logSpan.${key}`] = `${now - start}ms`
+  }
+  if (opts.cause.reasons.length > 0) {
+    extra.cause = Cause.pretty(opts.cause)
+  }
+
+  const svc = typeof extra.service === "string" ? extra.service : undefined
+  if (svc) delete extra.service
+  const log = svc ? Log.create({ service: svc }) : Log.Default
+  const msg = text(opts.message)
+
+  switch (opts.logLevel) {
+    case "Trace":
+    case "Debug":
+      return log.debug(msg, extra)
+    case "Warn":
+      return log.warn(msg, extra)
+    case "Error":
+    case "Fatal":
+      return log.error(msg, extra)
+    default:
+      return log.info(msg, extra)
+  }
+})
+
+export const layer = Logger.layer([logger], { mergeWithExisting: false })
+
+export const create = (base: Fields = {}): Handle => ({
+  debug: (msg, extra) => call((item) => Effect.logDebug(item), base, msg, extra),
+  info: (msg, extra) => call((item) => Effect.logInfo(item), base, msg, extra),
+  warn: (msg, extra) => call((item) => Effect.logWarning(item), base, msg, extra),
+  error: (msg, extra) => call((item) => Effect.logError(item), base, msg, extra),
+  with: (extra) => create({ ...base, ...extra }),
+})
diff --git a/packages/core/src/effect/memo-map.ts b/packages/core/src/effect/memo-map.ts
new file mode 100644
index 000000000..c797dbf42
--- /dev/null
+++ b/packages/core/src/effect/memo-map.ts
@@ -0,0 +1,3 @@
+import { Layer } from "effect"
+
+export const memoMap = Layer.makeMemoMapUnsafe()
diff --git a/packages/core/src/effect/observability.ts b/packages/core/src/effect/observability.ts
new file mode 100644
index 000000000..0203079ab
--- /dev/null
+++ b/packages/core/src/effect/observability.ts
@@ -0,0 +1,107 @@
+import { Effect, Layer, Logger } from "effect"
+import { FetchHttpClient } from "effect/unstable/http"
+import { OtlpLogger, OtlpSerialization } from "effect/unstable/observability"
+import * as EffectLogger from "./logger"
+import { Flag } from "../flag/flag"
+import { InstallationChannel, InstallationVersion } from "../installation/version"
+import { ensureProcessMetadata } from "../util/opencode-process"
+
+const base = Flag.OTEL_EXPORTER_OTLP_ENDPOINT
+export const enabled = !!base
+const processID = crypto.randomUUID()
+
+const headers = Flag.OTEL_EXPORTER_OTLP_HEADERS
+  ? Flag.OTEL_EXPORTER_OTLP_HEADERS.split(",").reduce(
+      (acc, x) => {
+        const [key, ...value] = x.split("=")
+        acc[key] = value.join("=")
+        return acc
+      },
+      {} as Record<string, string>,
+    )
+  : undefined
+
+export function resource(): { serviceName: string; serviceVersion: string; attributes: Record<string, string> } {
+  const processMetadata = ensureProcessMetadata("main")
+  const attributes: Record<string, string> = (() => {
+    const value = process.env.OTEL_RESOURCE_ATTRIBUTES
+    if (!value) return {}
+    try {
+      return Object.fromEntries(
+        value.split(",").map((entry) => {
+          const index = entry.indexOf("=")
+          if (index < 1) throw new Error("Invalid OTEL_RESOURCE_ATTRIBUTES entry")
+          return [decodeURIComponent(entry.slice(0, index)), decodeURIComponent(entry.slice(index + 1))]
+        }),
+      )
+    } catch {
+      return {}
+    }
+  })()
+
+  return {
+    serviceName: "opencode",
+    serviceVersion: InstallationVersion,
+    attributes: {
+      ...attributes,
+      "deployment.environment.name": InstallationChannel,
+      "opencode.client": Flag.OPENCODE_CLIENT,
+      "opencode.process_role": processMetadata.processRole,
+      "opencode.run_id": processMetadata.runID,
+      "service.instance.id": processID,
+    },
+  }
+}
+
+function logs() {
+  return Logger.layer(
+    [
+      EffectLogger.logger,
+      OtlpLogger.make({
+        url: `${base}/v1/logs`,
+        resource: resource(),
+        headers,
+      }),
+    ],
+    { mergeWithExisting: false },
+  ).pipe(Layer.provide(OtlpSerialization.layerJson), Layer.provide(FetchHttpClient.layer))
+}
+
+const traces = async () => {
+  const NodeSdk = await import("@effect/opentelemetry/NodeSdk")
+  const OTLP = await import("@opentelemetry/exporter-trace-otlp-http")
+  const SdkBase = await import("@opentelemetry/sdk-trace-base")
+
+  // @effect/opentelemetry creates a NodeTracerProvider but never calls
+  // register(), so the global @opentelemetry/api context manager stays
+  // as the no-op default. Non-Effect code (like the AI SDK) that calls
+  // tracer.startActiveSpan() relies on context.active() to find the
+  // parent span - without a real context manager every span starts a
+  // new trace. Registering AsyncLocalStorageContextManager fixes this.
+  const { AsyncLocalStorageContextManager } = await import("@opentelemetry/context-async-hooks")
+  const { context } = await import("@opentelemetry/api")
+  const mgr = new AsyncLocalStorageContextManager()
+  mgr.enable()
+  context.setGlobalContextManager(mgr)
+
+  return NodeSdk.layer(() => ({
+    resource: resource(),
+    spanProcessor: new SdkBase.BatchSpanProcessor(
+      new OTLP.OTLPTraceExporter({
+        url: `${base}/v1/traces`,
+        headers,
+      }),
+    ),
+  }))
+}
+
+export const layer = !base
+  ? EffectLogger.layer
+  : Layer.unwrap(
+      Effect.gen(function* () {
+        const trace = yield* Effect.promise(traces)
+        return Layer.mergeAll(trace, logs())
+      }),
+    )
+
+export const Observability = { enabled, layer }
diff --git a/packages/core/src/effect/runtime.ts b/packages/core/src/effect/runtime.ts
new file mode 100644
index 000000000..e4f682709
--- /dev/null
+++ b/packages/core/src/effect/runtime.ts
@@ -0,0 +1,21 @@
+import { Layer, type Context, ManagedRuntime, type Effect } from "effect"
+import { memoMap } from "./memo-map"
+import { Observability } from "./observability"
+
+export function makeRuntime<I, S, E>(service: Context.Service<I, S>, layer: Layer.Layer<I, E>) {
+  let rt: ManagedRuntime.ManagedRuntime<I, E> | undefined
+  const getRuntime = () =>
+    (rt ??= ManagedRuntime.make(Layer.provideMerge(layer, Observability.layer) as Layer.Layer<I, E>, {
+      memoMap,
+    }))
+
+  return {
+    runSync: <A, Err>(fn: (svc: S) => Effect.Effect<A, Err, I>) => getRuntime().runSync(service.use(fn)),
+    runPromiseExit: <A, Err>(fn: (svc: S) => Effect.Effect<A, Err, I>, options?: Effect.RunOptions) =>
+      getRuntime().runPromiseExit(service.use(fn), options),
+    runPromise: <A, Err>(fn: (svc: S) => Effect.Effect<A, Err, I>, options?: Effect.RunOptions) =>
+      getRuntime().runPromise(service.use(fn), options),
+    runFork: <A, Err>(fn: (svc: S) => Effect.Effect<A, Err, I>) => getRuntime().runFork(service.use(fn)),
+    runCallback: <A, Err>(fn: (svc: S) => Effect.Effect<A, Err, I>) => getRuntime().runCallback(service.use(fn)),
+  }
+}
diff --git a/packages/core/src/flag/flag.ts b/packages/core/src/flag/flag.ts
new file mode 100644
index 000000000..72c8931f5
--- /dev/null
+++ b/packages/core/src/flag/flag.ts
@@ -0,0 +1,107 @@
+import { Config } from "effect"
+
+function truthy(key: string) {
+  const value = process.env[key]?.toLowerCase()
+  return value === "true" || value === "1"
+}
+
+function falsy(key: string) {
+  const value = process.env[key]?.toLowerCase()
+  return value === "false" || value === "0"
+}
+
+function number(key: string) {
+  const value = process.env[key]
+  if (!value) return undefined
+  const parsed = Number(value)
+  return Number.isInteger(parsed) && parsed > 0 ? parsed : undefined
+}
+
+const OPENCODE_EXPERIMENTAL = truthy("OPENCODE_EXPERIMENTAL")
+const OPENCODE_DISABLE_CLAUDE_CODE = truthy("OPENCODE_DISABLE_CLAUDE_CODE")
+const OPENCODE_DISABLE_CLAUDE_CODE_SKILLS =
+  OPENCODE_DISABLE_CLAUDE_CODE || truthy("OPENCODE_DISABLE_CLAUDE_CODE_SKILLS")
+const copy = process.env["OPENCODE_EXPERIMENTAL_DISABLE_COPY_ON_SELECT"]
+
+export const Flag = {
+  OTEL_EXPORTER_OTLP_ENDPOINT: process.env["OTEL_EXPORTER_OTLP_ENDPOINT"],
+  OTEL_EXPORTER_OTLP_HEADERS: process.env["OTEL_EXPORTER_OTLP_HEADERS"],
+
+  OPENCODE_AUTO_SHARE: truthy("OPENCODE_AUTO_SHARE"),
+  OPENCODE_AUTO_HEAP_SNAPSHOT: truthy("OPENCODE_AUTO_HEAP_SNAPSHOT"),
+  OPENCODE_GIT_BASH_PATH: process.env["OPENCODE_GIT_BASH_PATH"],
+  OPENCODE_CONFIG: process.env["OPENCODE_CONFIG"],
+  OPENCODE_CONFIG_CONTENT: process.env["OPENCODE_CONFIG_CONTENT"],
+  OPENCODE_DISABLE_AUTOUPDATE: truthy("OPENCODE_DISABLE_AUTOUPDATE"),
+  OPENCODE_ALWAYS_NOTIFY_UPDATE: truthy("OPENCODE_ALWAYS_NOTIFY_UPDATE"),
+  OPENCODE_DISABLE_PRUNE: truthy("OPENCODE_DISABLE_PRUNE"),
+  OPENCODE_DISABLE_TERMINAL_TITLE: truthy("OPENCODE_DISABLE_TERMINAL_TITLE"),
+  OPENCODE_SHOW_TTFD: truthy("OPENCODE_SHOW_TTFD"),
+  OPENCODE_PERMISSION: process.env["OPENCODE_PERMISSION"],
+  OPENCODE_DISABLE_DEFAULT_PLUGINS: truthy("OPENCODE_DISABLE_DEFAULT_PLUGINS"),
+  OPENCODE_DISABLE_LSP_DOWNLOAD: truthy("OPENCODE_DISABLE_LSP_DOWNLOAD"),
+  OPENCODE_ENABLE_EXPERIMENTAL_MODELS: truthy("OPENCODE_ENABLE_EXPERIMENTAL_MODELS"),
+  OPENCODE_DISABLE_AUTOCOMPACT: truthy("OPENCODE_DISABLE_AUTOCOMPACT"),
+  OPENCODE_DISABLE_MODELS_FETCH: truthy("OPENCODE_DISABLE_MODELS_FETCH"),
+  OPENCODE_DISABLE_MOUSE: truthy("OPENCODE_DISABLE_MOUSE"),
+  OPENCODE_DISABLE_CLAUDE_CODE,
+  OPENCODE_DISABLE_CLAUDE_CODE_PROMPT: OPENCODE_DISABLE_CLAUDE_CODE || truthy("OPENCODE_DISABLE_CLAUDE_CODE_PROMPT"),
+  OPENCODE_DISABLE_CLAUDE_CODE_SKILLS,
+  OPENCODE_DISABLE_EXTERNAL_SKILLS: OPENCODE_DISABLE_CLAUDE_CODE_SKILLS || truthy("OPENCODE_DISABLE_EXTERNAL_SKILLS"),
+  OPENCODE_FAKE_VCS: process.env["OPENCODE_FAKE_VCS"],
+  OPENCODE_SERVER_PASSWORD: process.env["OPENCODE_SERVER_PASSWORD"],
+  OPENCODE_SERVER_USERNAME: process.env["OPENCODE_SERVER_USERNAME"],
+  OPENCODE_ENABLE_QUESTION_TOOL: truthy("OPENCODE_ENABLE_QUESTION_TOOL"),
+
+  // Experimental
+  OPENCODE_EXPERIMENTAL,
+  OPENCODE_EXPERIMENTAL_FILEWATCHER: Config.boolean("OPENCODE_EXPERIMENTAL_FILEWATCHER").pipe(
+    Config.withDefault(false),
+  ),
+  OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: Config.boolean("OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER").pipe(
+    Config.withDefault(false),
+  ),
+  OPENCODE_EXPERIMENTAL_ICON_DISCOVERY: OPENCODE_EXPERIMENTAL || truthy("OPENCODE_EXPERIMENTAL_ICON_DISCOVERY"),
+  OPENCODE_EXPERIMENTAL_DISABLE_COPY_ON_SELECT:
+    copy === undefined ? process.platform === "win32" : truthy("OPENCODE_EXPERIMENTAL_DISABLE_COPY_ON_SELECT"),
+  OPENCODE_ENABLE_EXA: truthy("OPENCODE_ENABLE_EXA") || OPENCODE_EXPERIMENTAL || truthy("OPENCODE_EXPERIMENTAL_EXA"),
+  OPENCODE_EXPERIMENTAL_BASH_DEFAULT_TIMEOUT_MS: number("OPENCODE_EXPERIMENTAL_BASH_DEFAULT_TIMEOUT_MS"),
+  OPENCODE_EXPERIMENTAL_OUTPUT_TOKEN_MAX: number("OPENCODE_EXPERIMENTAL_OUTPUT_TOKEN_MAX"),
+  OPENCODE_EXPERIMENTAL_OXFMT: OPENCODE_EXPERIMENTAL || truthy("OPENCODE_EXPERIMENTAL_OXFMT"),
+  OPENCODE_EXPERIMENTAL_LSP_TY: truthy("OPENCODE_EXPERIMENTAL_LSP_TY"),
+  OPENCODE_EXPERIMENTAL_LSP_TOOL: OPENCODE_EXPERIMENTAL || truthy("OPENCODE_EXPERIMENTAL_LSP_TOOL"),
+  OPENCODE_EXPERIMENTAL_PLAN_MODE: OPENCODE_EXPERIMENTAL || truthy("OPENCODE_EXPERIMENTAL_PLAN_MODE"),
+  OPENCODE_EXPERIMENTAL_MARKDOWN: !falsy("OPENCODE_EXPERIMENTAL_MARKDOWN"),
+  OPENCODE_MODELS_URL: process.env["OPENCODE_MODELS_URL"],
+  OPENCODE_MODELS_PATH: process.env["OPENCODE_MODELS_PATH"],
+  OPENCODE_DISABLE_EMBEDDED_WEB_UI: truthy("OPENCODE_DISABLE_EMBEDDED_WEB_UI"),
+  OPENCODE_DB: process.env["OPENCODE_DB"],
+  OPENCODE_DISABLE_CHANNEL_DB: truthy("OPENCODE_DISABLE_CHANNEL_DB"),
+  OPENCODE_SKIP_MIGRATIONS: truthy("OPENCODE_SKIP_MIGRATIONS"),
+  OPENCODE_STRICT_CONFIG_DEPS: truthy("OPENCODE_STRICT_CONFIG_DEPS"),
+
+  OPENCODE_WORKSPACE_ID: process.env["OPENCODE_WORKSPACE_ID"],
+  OPENCODE_EXPERIMENTAL_HTTPAPI: truthy("OPENCODE_EXPERIMENTAL_HTTPAPI"),
+  OPENCODE_EXPERIMENTAL_WORKSPACES: OPENCODE_EXPERIMENTAL || truthy("OPENCODE_EXPERIMENTAL_WORKSPACES"),
+
+  // Evaluated at access time (not module load) because tests, the CLI, and
+  // external tooling set these env vars at runtime.
+  get OPENCODE_DISABLE_PROJECT_CONFIG() {
+    return truthy("OPENCODE_DISABLE_PROJECT_CONFIG")
+  },
+  get OPENCODE_TUI_CONFIG() {
+    return process.env["OPENCODE_TUI_CONFIG"]
+  },
+  get OPENCODE_CONFIG_DIR() {
+    return process.env["OPENCODE_CONFIG_DIR"]
+  },
+  get OPENCODE_PURE() {
+    return truthy("OPENCODE_PURE")
+  },
+  get OPENCODE_PLUGIN_META_FILE() {
+    return process.env["OPENCODE_PLUGIN_META_FILE"]
+  },
+  get OPENCODE_CLIENT() {
+    return process.env["OPENCODE_CLIENT"] ?? "cli"
+  },
+}
diff --git a/packages/core/src/global.ts b/packages/core/src/global.ts
index 538cc091b..bf605618f 100644
--- a/packages/core/src/global.ts
+++ b/packages/core/src/global.ts
@@ -3,6 +3,24 @@ import { xdgData, xdgCache, xdgConfig, xdgState } from "xdg-basedir"
 import os from "os"
 import { Context, Effect, Layer } from "effect"
 
+const app = "opencode"
+const data = path.join(xdgData!, app)
+const cache = path.join(xdgCache!, app)
+const config = path.join(xdgConfig!, app)
+const state = path.join(xdgState!, app)
+
+export const Path = {
+  get home() {
+    return process.env.OPENCODE_TEST_HOME ?? os.homedir()
+  },
+  data,
+  bin: path.join(cache, "bin"),
+  log: path.join(data, "log"),
+  cache,
+  config,
+  state,
+}
+
 export namespace Global {
   export class Service extends Context.Service<Service, Interface>()("@opencode/Global") {}
 
@@ -19,23 +37,14 @@ export namespace Global {
   export const layer = Layer.effect(
     Service,
     Effect.gen(function* () {
-      const app = "opencode"
-      const home = process.env.OPENCODE_TEST_HOME ?? os.homedir()
-      const data = path.join(xdgData!, app)
-      const cache = path.join(xdgCache!, app)
-      const cfg = path.join(xdgConfig!, app)
-      const state = path.join(xdgState!, app)
-      const bin = path.join(cache, "bin")
-      const log = path.join(data, "log")
-
       return Service.of({
-        home,
-        data,
-        cache,
-        config: cfg,
-        state,
-        bin,
-        log,
+        home: Path.home,
+        data: Path.data,
+        cache: Path.cache,
+        config: Path.config,
+        state: Path.state,
+        bin: Path.bin,
+        log: Path.log,
       })
     }),
   )
diff --git a/packages/core/src/installation/version.ts b/packages/core/src/installation/version.ts
new file mode 100644
index 000000000..25d9cd99a
--- /dev/null
+++ b/packages/core/src/installation/version.ts
@@ -0,0 +1,8 @@
+declare global {
+  const OPENCODE_VERSION: string
+  const OPENCODE_CHANNEL: string
+}
+
+export const InstallationVersion = typeof OPENCODE_VERSION === "string" ? OPENCODE_VERSION : "local"
+export const InstallationChannel = typeof OPENCODE_CHANNEL === "string" ? OPENCODE_CHANNEL : "local"
+export const InstallationLocal = InstallationChannel === "local"
diff --git a/packages/core/src/util/log.ts b/packages/core/src/util/log.ts
new file mode 100644
index 000000000..a61c15f7a
--- /dev/null
+++ b/packages/core/src/util/log.ts
@@ -0,0 +1,185 @@
+import path from "path"
+import fs from "fs/promises"
+import { createWriteStream } from "fs"
+import * as Global from "../global"
+import z from "zod"
+import { Glob } from "./glob"
+
+export const Level = z.enum(["DEBUG", "INFO", "WARN", "ERROR"]).meta({ ref: "LogLevel", description: "Log level" })
+export type Level = z.infer<typeof Level>
+
+const levelPriority: Record<Level, number> = {
+  DEBUG: 0,
+  INFO: 1,
+  WARN: 2,
+  ERROR: 3,
+}
+const keep = 10
+
+let level: Level = "INFO"
+
+function shouldLog(input: Level): boolean {
+  return levelPriority[input] >= levelPriority[level]
+}
+
+export type Logger = {
+  debug(message?: any, extra?: Record<string, any>): void
+  info(message?: any, extra?: Record<string, any>): void
+  error(message?: any, extra?: Record<string, any>): void
+  warn(message?: any, extra?: Record<string, any>): void
+  tag(key: string, value: string): Logger
+  clone(): Logger
+  time(
+    message: string,
+    extra?: Record<string, any>,
+  ): {
+    stop(): void
+    [Symbol.dispose](): void
+  }
+}
+
+const loggers = new Map<string, Logger>()
+
+export const Default = create({ service: "default" })
+
+export interface Options {
+  print: boolean
+  dev?: boolean
+  level?: Level
+}
+
+let logpath = ""
+export function file() {
+  return logpath
+}
+let write = (msg: any) => {
+  process.stderr.write(msg)
+  return msg.length
+}
+
+export async function init(options: Options) {
+  if (options.level) level = options.level
+  void cleanup(Global.Path.log)
+  if (options.print) return
+  logpath = path.join(
+    Global.Path.log,
+    options.dev ? "dev.log" : new Date().toISOString().split(".")[0].replace(/:/g, "") + ".log",
+  )
+  await fs.truncate(logpath).catch(() => {})
+  const stream = createWriteStream(logpath, { flags: "a" })
+  write = async (msg: any) => {
+    return new Promise((resolve, reject) => {
+      stream.write(msg, (err) => {
+        if (err) reject(err)
+        else resolve(msg.length)
+      })
+    })
+  }
+}
+
+async function cleanup(dir: string) {
+  const files = (
+    await Glob.scan("????-??-??T??????.log", {
+      cwd: dir,
+      absolute: false,
+      include: "file",
+    }).catch(() => [])
+  )
+    .filter((file) => path.basename(file) === file)
+    .sort()
+  if (files.length <= keep) return
+
+  const doomed = files.slice(0, -keep)
+  await Promise.all(doomed.map((file) => fs.unlink(path.join(dir, file)).catch(() => {})))
+}
+
+function formatError(error: Error, depth = 0): string {
+  const result = error.message
+  return error.cause instanceof Error && depth < 10
+    ? result + " Caused by: " + formatError(error.cause, depth + 1)
+    : result
+}
+
+let last = Date.now()
+export function create(tags?: Record<string, any>) {
+  tags = tags || {}
+
+  const service = tags["service"]
+  if (service && typeof service === "string") {
+    const cached = loggers.get(service)
+    if (cached) {
+      return cached
+    }
+  }
+
+  function build(message: any, extra?: Record<string, any>) {
+    const prefix = Object.entries({
+      ...tags,
+      ...extra,
+    })
+      .filter(([_, value]) => value !== undefined && value !== null)
+      .map(([key, value]) => {
+        const prefix = `${key}=`
+        if (value instanceof Error) return prefix + formatError(value)
+        if (typeof value === "object") return prefix + JSON.stringify(value)
+        return prefix + value
+      })
+      .join(" ")
+    const next = new Date()
+    const diff = next.getTime() - last
+    last = next.getTime()
+    return [next.toISOString().split(".")[0], "+" + diff + "ms", prefix, message].filter(Boolean).join(" ") + "\n"
+  }
+  const result: Logger = {
+    debug(message?: any, extra?: Record<string, any>) {
+      if (shouldLog("DEBUG")) {
+        write("DEBUG " + build(message, extra))
+      }
+    },
+    info(message?: any, extra?: Record<string, any>) {
+      if (shouldLog("INFO")) {
+        write("INFO  " + build(message, extra))
+      }
+    },
+    error(message?: any, extra?: Record<string, any>) {
+      if (shouldLog("ERROR")) {
+        write("ERROR " + build(message, extra))
+      }
+    },
+    warn(message?: any, extra?: Record<string, any>) {
+      if (shouldLog("WARN")) {
+        write("WARN  " + build(message, extra))
+      }
+    },
+    tag(key: string, value: string) {
+      if (tags) tags[key] = value
+      return result
+    },
+    clone() {
+      return create({ ...tags })
+    },
+    time(message: string, extra?: Record<string, any>) {
+      const now = Date.now()
+      result.info(message, { status: "started", ...extra })
+      function stop() {
+        result.info(message, {
+          status: "completed",
+          duration: Date.now() - now,
+          ...extra,
+        })
+      }
+      return {
+        stop,
+        [Symbol.dispose]() {
+          stop()
+        },
+      }
+    },
+  }
+
+  if (service && typeof service === "string") {
+    loggers.set(service, result)
+  }
+
+  return result
+}
diff --git a/packages/core/src/util/opencode-process.ts b/packages/core/src/util/opencode-process.ts
new file mode 100644
index 000000000..f59270ad2
--- /dev/null
+++ b/packages/core/src/util/opencode-process.ts
@@ -0,0 +1,24 @@
+export const OPENCODE_RUN_ID = "OPENCODE_RUN_ID"
+export const OPENCODE_PROCESS_ROLE = "OPENCODE_PROCESS_ROLE"
+
+export function ensureRunID() {
+  return (process.env[OPENCODE_RUN_ID] ??= crypto.randomUUID())
+}
+
+export function ensureProcessRole(fallback: "main" | "worker") {
+  return (process.env[OPENCODE_PROCESS_ROLE] ??= fallback)
+}
+
+export function ensureProcessMetadata(fallback: "main" | "worker") {
+  return {
+    runID: ensureRunID(),
+    processRole: ensureProcessRole(fallback),
+  }
+}
+
+export function sanitizedProcessEnv(overrides?: Record<string, string>) {
+  const env = Object.fromEntries(
+    Object.entries(process.env).filter((entry): entry is [string, string] => entry[1] !== undefined),
+  )
+  return overrides ? Object.assign(env, overrides) : env
+}