test(core): tighten environment conformance cleanup

Co-authored-by: Kit Langton <kit.langton@gmail.com>

packages/core/package.json

@@ -17,6 +17,7 @@
     "opencode": "./bin/opencode"
   },
   "exports": {
+    "./environment": "./src/environment/index.ts",
     "./session/runner": "./src/session/runner/index.ts",
     "./instructions": "./src/instructions/index.ts",
     "./*": "./src/*.ts"

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

@@ -161,11 +161,14 @@ function isPathAction(action: string): action is PathAction {
 }
 
 function expandHome(resource: string, home: string) {
-  if (resource.startsWith("~/")) return home + resource.slice(1)
   if (resource === "~") return home
   if (resource === "$HOME") return home
-  if (resource.startsWith("$HOME/")) return home + resource.slice(5)
-  if (resource.startsWith("$HOME\\")) return home + resource.slice(5)
+  const relative = resource.startsWith("~/")
+    ? resource.slice(2)
+    : resource.startsWith("$HOME/") || resource.startsWith("$HOME\\")
+      ? resource.slice(6)
+      : undefined
+  if (relative !== undefined) return (path.posix.isAbsolute(home) ? path.posix : path.win32).join(home, relative)
   return resource
 }
 

packages/core/src/environment/driver.ts

@@ -0,0 +1,9 @@
+import type { ChildProcessSpawner } from "effect/unstable/process/ChildProcessSpawner"
+import type { FilesImpl } from "./files"
+
+export interface Driver {
+  readonly spawner: ChildProcessSpawner["Service"]
+  readonly overrides?: Partial<FilesImpl>
+}
+
+export * as EnvironmentDriver from "./driver"

packages/core/src/environment/exec-defaults.ts

@@ -0,0 +1,185 @@
+import { Effect, Stream } from "effect"
+import { ChildProcess } from "effect/unstable/process"
+import type { ChildProcessSpawner } from "effect/unstable/process/ChildProcessSpawner"
+import { collectStream } from "@opencode-ai/util/process"
+import { Failed, NotFound, WrongKind, type FileInfo, type FileType, type FilesImpl } from "./files"
+
+const MAX_DATA_BYTES = 64 * 1024 * 1024
+const MAX_ERROR_BYTES = 64 * 1024
+const NOT_FOUND = 44
+const WRONG_KIND = 45
+const FAILED = 46
+
+const loadMetadata = (flags = "") => `
+metadata=$(stat ${flags} -c '%F\t%s\t%Y' -- "$1" 2>&1) || {
+  case "$metadata" in
+    *'No such file or directory'*|*'Not a directory'*) exit ${NOT_FOUND} ;;
+    *) printf '%s' "$metadata" >&2; exit ${FAILED} ;;
+  esac
+}
+`
+
+const statScript = `
+${loadMetadata()}
+printf '%s\n' "$metadata"
+`
+
+const readScript = `
+${loadMetadata("-L")}
+kind=\${metadata%%	*}
+if [ "$kind" != 'regular file' ] && [ "$kind" != 'regular empty file' ]; then
+  printf '%s' "$kind" >&2
+  exit ${WRONG_KIND}
+fi
+printf '%s\n' "$metadata"
+if [ "$2" = range ]; then
+  dd if="$1" iflag=skip_bytes,count_bytes skip="$3" count="$4" status=none
+else
+  cat -- "$1"
+fi
+`
+
+const listScript = `
+${loadMetadata()}
+kind=\${metadata%%	*}
+if [ "$kind" != directory ]; then
+  printf '%s' "$kind" >&2
+  exit ${WRONG_KIND}
+fi
+find "$1" -mindepth 1 -maxdepth 1 -printf '%y\0%f\0'
+`
+
+interface Result {
+  readonly exitCode: number
+  readonly stdout: Uint8Array
+  readonly stderr: Uint8Array
+}
+
+export const execDefaults = (spawner: ChildProcessSpawner["Service"]): FilesImpl => {
+  const run = (
+    path: string,
+    script: string,
+    args: ReadonlyArray<string> = [],
+    stdin?: Uint8Array,
+  ): Effect.Effect<Result, Failed> =>
+    Effect.scoped(
+      Effect.gen(function* () {
+        const command = ChildProcess.make("sh", ["-c", script, "sh", path, ...args], {
+          env: { LC_ALL: "C" },
+          extendEnv: true,
+          stdin: stdin === undefined ? undefined : Stream.make(stdin),
+        })
+        const handle = yield* spawner.spawn(command).pipe(Effect.mapError((cause) => new Failed({ path, cause })))
+        const [stdout, stderr, exitCode] = yield* Effect.all(
+          [
+            collectStream(handle.stdout, MAX_DATA_BYTES),
+            collectStream(handle.stderr, MAX_ERROR_BYTES),
+            handle.exitCode,
+          ],
+          { concurrency: "unbounded" },
+        ).pipe(Effect.mapError((cause) => new Failed({ path, cause })))
+        if (stdout.truncated || stderr.truncated) {
+          return yield* new Failed({ path, cause: new Error("Process output exceeded its collection limit") })
+        }
+        return { exitCode, stdout: stdout.buffer, stderr: stderr.buffer }
+      }),
+    )
+
+  const classify = <A>(
+    path: string,
+    result: Result,
+    success: (stdout: Uint8Array) => A,
+  ): Effect.Effect<A, NotFound | WrongKind | Failed> => {
+    if (result.exitCode === 0) return Effect.sync(() => success(result.stdout))
+    if (result.exitCode === NOT_FOUND) return Effect.fail(new NotFound({ path }))
+    if (result.exitCode === WRONG_KIND) {
+      return Effect.fail(new WrongKind({ path, actual: parseType(new TextDecoder().decode(result.stderr)) }))
+    }
+    return Effect.fail(processFailure(path, result))
+  }
+
+  const stat: FilesImpl["stat"] = (path) =>
+    run(path, statScript).pipe(Effect.flatMap((result) => classifyStat(path, result)))
+
+  const complete = (path: string, result: Result) =>
+    result.exitCode === 0 ? Effect.void : Effect.fail(processFailure(path, result))
+
+  return {
+    stat,
+    read: (path, range) =>
+      run(
+        path,
+        readScript,
+        range === undefined ? ["whole"] : ["range", String(range.offset), String(range.length)],
+      ).pipe(
+        Effect.flatMap((result) =>
+          classify(path, result, (stdout) => {
+            const newline = stdout.indexOf(10)
+            if (newline < 0) throw new Error("Missing read metadata header")
+            return {
+              info: parseInfo(stdout.slice(0, newline)),
+              bytes: stdout.slice(newline + 1),
+            }
+          }),
+        ),
+      ),
+    write: (path, bytes) =>
+      run(path, `mkdir -p "$(dirname "$1")" && cat > "$1"`, [], bytes).pipe(
+        Effect.flatMap((result) => complete(path, result)),
+      ),
+    list: (path) => run(path, listScript).pipe(Effect.flatMap((result) => classify(path, result, parseList))),
+    remove: (path) => run(path, `rm -rf -- "$1"`).pipe(Effect.flatMap((result) => complete(path, result))),
+    move: (from, to) =>
+      run(
+        from,
+        `${loadMetadata()}
+mv -- "$1" "$2"`,
+        [to],
+      ).pipe(Effect.flatMap((result) => classifyMove(from, result))),
+    mkdir: (path) => run(path, `mkdir -p -- "$1"`).pipe(Effect.flatMap((result) => complete(path, result))),
+  }
+}
+
+const classifyStat = (path: string, result: Result): Effect.Effect<FileInfo, NotFound | Failed> => {
+  if (result.exitCode === 0) return Effect.sync(() => parseInfo(result.stdout))
+  if (result.exitCode === NOT_FOUND) return Effect.fail(new NotFound({ path }))
+  return Effect.fail(processFailure(path, result))
+}
+
+const classifyMove = (path: string, result: Result): Effect.Effect<void, NotFound | Failed> => {
+  if (result.exitCode === 0) return Effect.void
+  if (result.exitCode === NOT_FOUND) return Effect.fail(new NotFound({ path }))
+  return Effect.fail(processFailure(path, result))
+}
+
+const processFailure = (path: string, result: Result) =>
+  new Failed({
+    path,
+    cause: new Error(new TextDecoder().decode(result.stderr).trim() || `Process exited with code ${result.exitCode}`),
+  })
+
+const parseInfo = (bytes: Uint8Array): FileInfo => {
+  const [rawType, rawSize, rawMtime] = new TextDecoder().decode(bytes).trim().split("\t")
+  const size = Number(rawSize)
+  const mtimeMs = Number(rawMtime) * 1_000
+  if (!rawType || !Number.isFinite(size) || !Number.isFinite(mtimeMs)) throw new Error("Invalid stat output")
+  return { type: parseType(rawType), size, mtimeMs }
+}
+
+const parseType = (value: string): FileType => {
+  if (value === "regular file" || value === "regular empty file" || value === "f") return "file"
+  if (value === "directory" || value === "d") return "directory"
+  if (value === "symbolic link" || value === "l") return "symlink"
+  return "other"
+}
+
+const parseList = (bytes: Uint8Array) => {
+  const fields = new TextDecoder().decode(bytes).split("\0")
+  fields.pop()
+  if (fields.length % 2 !== 0) throw new Error("Invalid find output")
+  return fields
+    .filter((_, index) => index % 2 === 0)
+    .map((type, index) => ({ name: fields[index * 2 + 1], type: parseType(type) }))
+}
+
+export * as EnvironmentExecDefaults from "./exec-defaults"

packages/core/src/environment/files.ts

@@ -0,0 +1,53 @@
+import { Effect, Schema } from "effect"
+
+export const FileType = Schema.Literals(["file", "directory", "symlink", "other"])
+export type FileType = typeof FileType.Type
+
+export interface FileInfo {
+  readonly type: FileType
+  readonly size: number
+  readonly mtimeMs: number
+}
+
+export interface DirEntry {
+  readonly name: string
+  readonly type: FileType
+}
+
+export class NotFound extends Schema.TaggedErrorClass<NotFound>()("Environment.NotFound", {
+  path: Schema.String,
+}) {}
+
+export class WrongKind extends Schema.TaggedErrorClass<WrongKind>()("Environment.WrongKind", {
+  path: Schema.String,
+  actual: FileType,
+}) {}
+
+export class Failed extends Schema.TaggedErrorClass<Failed>()("Environment.Failed", {
+  path: Schema.String,
+  cause: Schema.Defect(),
+}) {}
+
+export interface FilesImpl {
+  /**
+   * Reads a file, following a final symlink so `info` describes the target whose bytes are returned.
+   * The process-backed default caps collected output at 64 MiB; larger whole-file reads fail with
+   * `Failed`, so callers must use ranges for larger files.
+   */
+  readonly read: (
+    path: string,
+    range?: { readonly offset: number; readonly length: number },
+  ) => Effect.Effect<{ readonly info: FileInfo; readonly bytes: Uint8Array }, NotFound | WrongKind | Failed>
+  readonly write: (path: string, bytes: Uint8Array) => Effect.Effect<void, Failed>
+  /** Describes the path entry itself, so a final symlink is reported as `symlink` rather than followed. */
+  readonly stat: (path: string) => Effect.Effect<FileInfo, NotFound | Failed>
+  /** Lists a directory entry without following a final symlink; intermediate symlinks are traversed. */
+  readonly list: (path: string) => Effect.Effect<ReadonlyArray<DirEntry>, NotFound | WrongKind | Failed>
+  readonly remove: (path: string) => Effect.Effect<void, Failed>
+  readonly move: (from: string, to: string) => Effect.Effect<void, NotFound | Failed>
+  readonly mkdir: (path: string) => Effect.Effect<void, Failed>
+}
+
+export interface Files extends FilesImpl {}
+
+export * as EnvironmentFiles from "./files"

packages/core/src/environment/index.ts

@@ -0,0 +1,24 @@
+export * as Environment from "./index"
+
+export { type Driver } from "./driver"
+export {
+  type DirEntry,
+  Failed,
+  type FileInfo,
+  type Files,
+  type FilesImpl,
+  type FileType,
+  NotFound,
+  WrongKind,
+} from "./files"
+export { execDefaults } from "./exec-defaults"
+export { makeMemoryDriver, type MemoryDriver } from "./memory"
+
+import type { Driver } from "./driver"
+import { execDefaults } from "./exec-defaults"
+import type { Files } from "./files"
+
+export const makeFiles = (driver: Driver): Files => ({
+  ...execDefaults(driver.spawner),
+  ...driver.overrides,
+})

packages/core/src/environment/memory.ts

@@ -0,0 +1,168 @@
+import path from "node:path"
+import { Effect, PlatformError } from "effect"
+import { make } from "effect/unstable/process/ChildProcessSpawner"
+import type { Driver } from "./driver"
+import { Failed, NotFound, WrongKind, type FileInfo, type FilesImpl, type FileType } from "./files"
+
+type Node =
+  | { readonly type: "file"; readonly bytes: Uint8Array; readonly mtimeMs: number }
+  | { readonly type: "directory"; readonly mtimeMs: number }
+  | { readonly type: "symlink"; readonly target: string; readonly mtimeMs: number }
+
+export interface MemoryDriver extends Driver {
+  readonly symlink: (target: string, path: string) => Effect.Effect<void, Failed>
+}
+
+export const makeMemoryDriver = (): MemoryDriver => {
+  const nodes = new Map<string, Node>([["/", { type: "directory", mtimeMs: Date.now() }]])
+  const key = (value: string) => path.posix.resolve("/", value)
+  const info = (node: Node): FileInfo => ({
+    type: node.type,
+    size:
+      node.type === "file"
+        ? node.bytes.length
+        : node.type === "symlink"
+          ? new TextEncoder().encode(node.target).length
+          : 0,
+    mtimeMs: node.mtimeMs,
+  })
+  const resolveKey = (value: string, followFinal: boolean, seen = new Set<string>()): string | undefined => {
+    const normalized = key(value)
+    const parts = normalized.split("/").filter(Boolean)
+    const base = "/"
+    const walk = (current: string, index: number): string | undefined => {
+      if (index === parts.length) return current
+      const part = parts[index]
+      const candidate = path.posix.join(current, part)
+      const node = nodes.get(candidate)
+      if (node?.type !== "symlink" || (!followFinal && index === parts.length - 1)) return walk(candidate, index + 1)
+      if (seen.has(candidate)) return undefined
+      seen.add(candidate)
+      const target = path.posix.resolve(path.posix.dirname(candidate), node.target)
+      return resolveKey(path.posix.join(target, ...parts.slice(index + 1)), followFinal, seen)
+    }
+    return walk(base, 0)
+  }
+  const lookup = (value: string) => nodes.get(resolveKey(value, false) ?? key(value))
+  const requireParent = (value: string) => {
+    const parentPath = path.posix.dirname(key(value))
+    const parent = nodes.get(resolveKey(parentPath, true) ?? parentPath)
+    if (!parent) throw new Error(`Parent directory does not exist: ${path.posix.dirname(value)}`)
+    if (parent.type !== "directory") throw new Error(`Parent is not a directory: ${path.posix.dirname(value)}`)
+  }
+  const mkdirSync = (value: string) => {
+    const target = resolveKey(value, false) ?? key(value)
+    const existing = nodes.get(target)
+    if (existing?.type === "directory") return
+    if (existing) throw new Error(`Path is not a directory: ${value}`)
+    const parent = path.posix.dirname(target)
+    if (parent !== target) mkdirSync(parent)
+    nodes.set(target, { type: "directory", mtimeMs: Date.now() })
+  }
+  const failed = (value: string, cause: unknown) => new Failed({ path: value, cause })
+  const overrides: FilesImpl = {
+    stat: (value) => {
+      const node = lookup(value)
+      return node ? Effect.succeed(info(node)) : Effect.fail(new NotFound({ path: value }))
+    },
+    read: (value, range) => {
+      const original = lookup(value)
+      if (!original) return Effect.fail(new NotFound({ path: value }))
+      if (original.type === "directory") return Effect.fail(new WrongKind({ path: value, actual: "directory" }))
+      const resolved = resolveKey(value, true)
+      const node = resolved === undefined ? undefined : nodes.get(resolved)
+      if (!node) return Effect.fail(new NotFound({ path: value }))
+      if (node.type !== "file") return Effect.fail(new WrongKind({ path: value, actual: node.type }))
+      const bytes = range === undefined ? node.bytes : node.bytes.subarray(range.offset, range.offset + range.length)
+      return Effect.succeed({ info: info(node), bytes: bytes.slice() })
+    },
+    write: (value, bytes) =>
+      Effect.try({
+        try: () => {
+          mkdirSync(path.posix.dirname(key(value)))
+          const existing = lookup(value)
+          if (existing?.type === "directory") throw new Error(`Path is a directory: ${value}`)
+          const target = existing?.type === "symlink" ? resolveKey(value, true) : resolveKey(value, false)
+          if (!target) throw new Error(`Cannot resolve symlink: ${value}`)
+          requireParent(target)
+          nodes.set(target, { type: "file", bytes: bytes.slice(), mtimeMs: Date.now() })
+        },
+        catch: (cause) => failed(value, cause),
+      }),
+    list: (value) => {
+      const target = resolveKey(value, false) ?? key(value)
+      const node = nodes.get(target)
+      if (!node) return Effect.fail(new NotFound({ path: value }))
+      if (node.type !== "directory") return Effect.fail(new WrongKind({ path: value, actual: node.type }))
+      const entries = [...nodes.entries()]
+        .filter(([entry]) => entry !== target && path.posix.dirname(entry) === target)
+        .map(([entry, child]) => ({ name: path.posix.basename(entry), type: child.type satisfies FileType }))
+        .sort((a, b) => a.name.localeCompare(b.name))
+      return Effect.succeed(entries)
+    },
+    remove: (value) =>
+      Effect.sync(() => {
+        const target = resolveKey(value, false) ?? key(value)
+        for (const entry of nodes.keys()) {
+          if (entry === target || entry.startsWith(`${target}/`)) nodes.delete(entry)
+        }
+      }),
+    move: (from, to) => {
+      const source = resolveKey(from, false) ?? key(from)
+      const node = nodes.get(source)
+      if (!node) return Effect.fail(new NotFound({ path: from }))
+      return Effect.try({
+        try: () => {
+          const requested = resolveKey(to, false) ?? key(to)
+          const destination =
+            nodes.get(requested)?.type === "directory"
+              ? path.posix.join(requested, path.posix.basename(source))
+              : requested
+          if (node.type === "directory" && destination.startsWith(`${source}/`)) {
+            throw new Error(`Cannot move a directory into itself: ${from}`)
+          }
+          const existing = nodes.get(destination)
+          if (node.type === "directory" && existing && existing.type !== "directory") {
+            throw new Error(`Cannot overwrite a non-directory with a directory: ${to}`)
+          }
+          requireParent(destination)
+          const moved = [...nodes.entries()].filter(([entry]) => entry === source || entry.startsWith(`${source}/`))
+          for (const [entry] of moved) nodes.delete(entry)
+          for (const [entry, child] of moved) nodes.set(`${destination}${entry.slice(source.length)}`, child)
+        },
+        catch: (cause) => failed(from, cause),
+      })
+    },
+    mkdir: (value) => Effect.try({ try: () => mkdirSync(value), catch: (cause) => failed(value, cause) }),
+  }
+
+  const spawner = make((command) =>
+    Effect.suspend(() => {
+      const description = command._tag === "StandardCommand" ? command.command : "pipeline"
+      return Effect.fail(
+        PlatformError.systemError({
+          _tag: "Unknown",
+          module: "EnvironmentMemory",
+          method: "spawn",
+          pathOrDescriptor: description,
+          cause: failed(description, new Error("The memory driver cannot spawn processes")),
+        }),
+      )
+    }),
+  )
+
+  return {
+    spawner,
+    overrides,
+    symlink: (target, value) =>
+      Effect.try({
+        try: () => {
+          requireParent(value)
+          nodes.set(resolveKey(value, false) ?? key(value), { type: "symlink", target, mtimeMs: Date.now() })
+        },
+        catch: (cause) => failed(value, cause),
+      }),
+  }
+}
+
+export * as EnvironmentMemory from "./memory"

packages/core/src/skill.ts

@@ -2,7 +2,7 @@ export * as Skill from "./skill"
 
 import { makeLocationNode } from "@opencode-ai/util/effect/app-node"
 import path from "path"
-import { Context, Effect, Layer, Schema, Scope, Stream, Types } from "effect"
+import { Context, Effect, Layer, Schema, Stream, Types } from "effect"
 import { FileSystem } from "@opencode-ai/schema/filesystem"
 import { Skill } from "@opencode-ai/schema/skill"
 import { Agent } from "./agent"
@@ -13,7 +13,6 @@ import { Permission } from "./permission"
 import { AbsolutePath } from "./schema"
 import { SkillDiscovery } from "./skill/discovery"
 import { State } from "./state"
-import { Watcher } from "./filesystem/watcher"
 
 export const DirectorySource = Skill.DirectorySource
 export type DirectorySource = Skill.DirectorySource
@@ -82,51 +81,6 @@ const layer = Layer.effect(
     const discovery = yield* SkillDiscovery.Service
     const fs = yield* FSUtil.Service
     const bus = yield* Bus.Service
-    const watcher = yield* Watcher.Service
-    const scope = yield* Scope.Scope
-    const cache = new Map<string, { skills: Info[]; paths: readonly string[] }>()
-    const watched = new Set<string>()
-
-    const invalidate = Effect.fn("Skill.invalidateFromWatcher")(function* (file: string) {
-      const invalidated = Array.from(cache.entries()).filter(([, loaded]) =>
-        loaded.paths.some((item) => FSUtil.overlaps(item, file)),
-      )
-      if (invalidated.length === 0) return
-      for (const [key] of invalidated) cache.delete(key)
-      yield* Effect.logInfo("skill cache invalidated", {
-        file,
-        sources: invalidated.map(([key]) => key),
-        skills: invalidated.flatMap(([, loaded]) => loaded.skills.map((skill) => skill.id)),
-      })
-      yield* bus.publish(Skill.Event.Updated, {}).pipe(Effect.asVoid)
-    })
-
-    const watch = Effect.fn("Skill.watch")(function* (directory: string) {
-      const target = path.resolve(directory)
-      if (watched.has(target)) return
-      watched.add(target)
-      const updates = yield* watcher.subscribe({ path: target, type: "directory" })
-      yield* updates.pipe(
-        Stream.runForEach((update) => invalidate(update.path)),
-        Effect.forkIn(scope, { startImmediately: true }),
-      )
-    })
-
-    const watchDirectory = Effect.fn("Skill.watchDirectory")(function* (directory: string) {
-      const target = path.resolve(directory)
-      const resolved = yield* fs.realPath(directory).pipe(Effect.catch(() => Effect.succeed(undefined)))
-      if (resolved) {
-        yield* watch(resolved)
-        if (resolved !== target) {
-          yield* watch(path.dirname(target))
-        }
-        return resolved === target ? [target] : [target, resolved]
-      }
-      if (yield* fs.isDir(path.dirname(target))) {
-        yield* watch(path.dirname(target))
-      }
-      return [target]
-    })
 
     const state = State.create<Data, Draft>({
       name: "skill",
@@ -138,8 +92,7 @@ const layer = Layer.effect(
         },
         list: () => draft.sources as Source[],
       }),
-      finalize: () =>
-        Effect.sync(() => cache.clear()).pipe(Effect.andThen(bus.publish(Skill.Event.Updated, {})), Effect.asVoid),
+      finalize: () => bus.publish(Skill.Event.Updated, {}).pipe(Effect.asVoid),
     })
 
     const load = Effect.fn("Skill.load")(function* (source: Source) {
@@ -151,22 +104,14 @@ const layer = Layer.effect(
           directories: [],
           skills: [source.skill.id],
         })
-        return { skills: [source.skill], paths: [] }
+        return { skills: [source.skill], directories: [] }
       }
       const directories = source.type === "directory" ? [source.path] : yield* discovery.pull(source.url)
-      const roots = (yield* Effect.forEach(directories, watchDirectory)).flat()
-      const paths = [...roots]
       for (const directory of directories) {
         const files = yield* fs
           .scan("{*.md,**/SKILL.md}", { cwd: directory, absolute: true, include: "file", symlink: true, dot: true })
           .pipe(Effect.catch(() => Effect.succeed([] as string[])))
         for (const filepath of files.toSorted()) {
-          const resolved = yield* fs.realPath(filepath).pipe(Effect.catch(() => Effect.succeed(filepath)))
-          if (!roots.some((root) => FSUtil.contains(root, resolved))) {
-            const external = path.dirname(resolved)
-            paths.push(external)
-            yield* watch(external)
-          }
           const content = yield* fs.readFileStringSafe(filepath).pipe(Effect.catch(() => Effect.succeed(undefined)))
           if (!content) continue
           const markdown = ConfigMarkdown.parseOption(content)
@@ -194,7 +139,22 @@ const layer = Layer.effect(
         directories,
         skills: skills.map((skill) => skill.id),
       })
-      return { skills, paths }
+      return { skills, directories }
+    })
+
+    const cache = new Map<string, { skills: Info[]; directories: readonly string[] }>()
+    const invalidate = Effect.fn("Skill.invalidateFromWatcher")(function* (file: string) {
+      const invalidated = Array.from(cache.entries()).filter(([, loaded]) =>
+        loaded.directories.some((directory) => FSUtil.contains(directory, file)),
+      )
+      if (invalidated.length === 0) return
+      for (const [key] of invalidated) cache.delete(key)
+      yield* Effect.logInfo("skill cache invalidated", {
+        file,
+        sources: invalidated.map(([key]) => key),
+        skills: invalidated.flatMap(([, loaded]) => loaded.skills.map((skill) => skill.id)),
+      })
+      yield* bus.publish(Skill.Event.Updated, {}).pipe(Effect.asVoid)
     })
 
     yield* bus.subscribe(FileSystem.Event.Changed).pipe(
@@ -227,5 +187,5 @@ const layer = Layer.effect(
 export const node = makeLocationNode({
   service: Service,
   layer,
-  deps: [SkillDiscovery.node, FSUtil.node, Bus.node, Watcher.node],
+  deps: [SkillDiscovery.node, FSUtil.node, Bus.node],
 })

packages/core/test/config/agent.test.ts

@@ -51,6 +51,11 @@ describe("ConfigAgentPlugin.Plugin", () => {
   it.effect("matches Windows paths against home-relative permissions", () =>
     Effect.gen(function* () {
       const permissions = yield* loadHomePermissions("C:\\Users\\test")
+      expect(permissions).toContainEqual({
+        action: "external_directory",
+        resource: "C:\\Users\\test\\p\\**",
+        effect: "allow",
+      })
       expect(
         Permission.evaluate("external_directory", "C:\\Users\\test\\p\\opencode\\src\\*", permissions).effect,
       ).toBe("allow")

packages/core/test/environment.test.ts

@@ -0,0 +1,40 @@
+import fs from "node:fs/promises"
+import { Effect } from "effect"
+import { ChildProcessSpawner } from "effect/unstable/process"
+import { CrossSpawnSpawner } from "@opencode-ai/util/cross-spawn-spawner"
+import { LayerNode } from "@opencode-ai/util/effect/layer-node"
+import { execDefaults, Failed, makeFiles, makeMemoryDriver } from "../src/environment/index"
+import { tmpdir } from "./fixture/tmpdir"
+import { environmentConformance } from "./lib/environment-conformance"
+
+environmentConformance("memory environment", () => {
+  const driver = makeMemoryDriver()
+  return {
+    files: makeFiles(driver),
+    root: `/workspace-${crypto.randomUUID()}`,
+    symlink: driver.symlink,
+  }
+})
+
+environmentConformance(
+  "GNU exec environment",
+  async () => {
+    const spawner = await Effect.runPromise(
+      Effect.gen(function* () {
+        return yield* ChildProcessSpawner.ChildProcessSpawner
+      }).pipe(Effect.provide(LayerNode.compile(CrossSpawnSpawner.node))),
+    )
+    const tmp = await tmpdir("opencode-environment-")
+    return {
+      files: execDefaults(spawner),
+      root: tmp.path,
+      symlink: (target: string, link: string) =>
+        Effect.tryPromise({
+          try: () => fs.symlink(target, link),
+          catch: (cause) => new Failed({ path: link, cause }),
+        }),
+      dispose: () => tmp[Symbol.asyncDispose](),
+    }
+  },
+  process.platform !== "linux",
+)

packages/core/test/lib/environment-conformance.ts

@@ -0,0 +1,148 @@
+import { describe, expect, test } from "bun:test"
+import { Effect } from "effect"
+import { Failed, NotFound, WrongKind, type Files } from "../../src/environment/index"
+
+export interface EnvironmentHarness {
+  readonly files: Files
+  readonly root: string
+  readonly symlink?: (target: string, path: string) => Effect.Effect<void, Failed>
+  readonly dispose?: () => Promise<void>
+}
+
+export const environmentConformance = (
+  name: string,
+  makeHarness: () => EnvironmentHarness | Promise<EnvironmentHarness>,
+  skip = false,
+) => {
+  const check = (title: string, body: (harness: EnvironmentHarness) => Promise<void>) =>
+    test(title, async () => {
+      const harness = await makeHarness()
+      try {
+        await Effect.runPromise(harness.files.mkdir(harness.root))
+        await body(harness)
+      } finally {
+        try {
+          await Effect.runPromise(harness.files.remove(harness.root))
+        } finally {
+          await harness.dispose?.()
+        }
+      }
+    })
+
+  const bytes = (value: string) => new TextEncoder().encode(value)
+  const text = (value: Uint8Array) => new TextDecoder().decode(value)
+  const failure = <E>(effect: Effect.Effect<unknown, E>) => Effect.runPromise(Effect.flip(effect))
+
+  const suite = skip ? describe.skip : describe
+
+  suite(name, () => {
+    check("writes, stats, and reads a file with its info", async ({ files, root }) => {
+      const target = `${root}/hello.txt`
+      await Effect.runPromise(files.write(target, bytes("hello")))
+      const result = await Effect.runPromise(files.read(target))
+      expect(text(result.bytes)).toBe("hello")
+      expect(result.info.type).toBe("file")
+      expect(result.info.size).toBe(5)
+      expect(await Effect.runPromise(files.stat(target))).toEqual(result.info)
+    })
+
+    check("reports missing paths", async ({ files, root }) => {
+      const target = `${root}/missing`
+      expect(await failure(files.read(target))).toBeInstanceOf(NotFound)
+      expect(await failure(files.stat(target))).toBeInstanceOf(NotFound)
+      expect(await failure(files.list(target))).toBeInstanceOf(NotFound)
+      expect(await failure(files.move(target, `${root}/other`))).toBeInstanceOf(NotFound)
+    })
+
+    check("reports the actual kind", async ({ files, root }) => {
+      const directory = `${root}/directory`
+      const file = `${root}/file`
+      await Effect.runPromise(files.mkdir(directory))
+      await Effect.runPromise(files.write(file, bytes("data")))
+      const readError = await failure(files.read(directory))
+      const listError = await failure(files.list(file))
+      expect(readError).toBeInstanceOf(WrongKind)
+      expect((readError as WrongKind).actual).toBe("directory")
+      expect(listError).toBeInstanceOf(WrongKind)
+      expect((listError as WrongKind).actual).toBe("file")
+    })
+
+    check("write creates parent directories", async ({ files, root }) => {
+      const target = `${root}/one/two/file`
+      await Effect.runPromise(files.write(target, bytes("nested")))
+      await Effect.runPromise(files.write(`${root}/empty`, new Uint8Array()))
+      expect((await Effect.runPromise(files.stat(`${root}/one/two`))).type).toBe("directory")
+      expect(await Effect.runPromise(files.stat(`${root}/empty`))).toMatchObject({ type: "file", size: 0 })
+      expect(text((await Effect.runPromise(files.read(target))).bytes)).toBe("nested")
+    })
+
+    check("reads byte ranges", async ({ files, root }) => {
+      const target = `${root}/range`
+      await Effect.runPromise(files.write(target, bytes("0123456789")))
+      expect(text((await Effect.runPromise(files.read(target, { offset: 2, length: 4 }))).bytes)).toBe("2345")
+      expect(text((await Effect.runPromise(files.read(target, { offset: 8, length: 8 }))).bytes)).toBe("89")
+      expect(text((await Effect.runPromise(files.read(target, { offset: 20, length: 4 }))).bytes)).toBe("")
+    })
+
+    check("lists immediate entries with their kinds", async ({ files, root }) => {
+      await Effect.runPromise(files.write(`${root}/file name`, bytes("data")))
+      await Effect.runPromise(files.mkdir(`${root}/directory`))
+      await Effect.runPromise(files.write(`${root}/directory/nested`, bytes("nested")))
+      const entries = await Effect.runPromise(files.list(root))
+      expect(entries.toSorted((a, b) => a.name.localeCompare(b.name))).toEqual([
+        { name: "directory", type: "directory" },
+        { name: "file name", type: "file" },
+      ])
+    })
+
+    check("reports symlinks without resolving them", async (harness) => {
+      if (!harness.symlink) return
+      await Effect.runPromise(harness.files.write(`${harness.root}/target`, bytes("target")))
+      await Effect.runPromise(harness.files.write(`${harness.root}/target-dir/file`, bytes("through link")))
+      await Effect.runPromise(harness.symlink("target", `${harness.root}/link`))
+      await Effect.runPromise(harness.symlink("target-dir", `${harness.root}/link-dir`))
+      expect((await Effect.runPromise(harness.files.stat(`${harness.root}/link`))).type).toBe("symlink")
+      expect(await Effect.runPromise(harness.files.list(harness.root))).toContainEqual({
+        name: "link",
+        type: "symlink",
+      })
+      expect(text((await Effect.runPromise(harness.files.read(`${harness.root}/link-dir/file`))).bytes)).toBe(
+        "through link",
+      )
+      const listError = await failure(harness.files.list(`${harness.root}/link-dir`))
+      expect(listError).toBeInstanceOf(WrongKind)
+      expect((listError as WrongKind).actual).toBe("symlink")
+    })
+
+    check("follows symlinks when reading", async (harness) => {
+      if (!harness.symlink) return
+      await Effect.runPromise(harness.files.write(`${harness.root}/target`, bytes("target content")))
+      await Effect.runPromise(harness.files.mkdir(`${harness.root}/directory`))
+      await Effect.runPromise(harness.symlink("target", `${harness.root}/file-link`))
+      await Effect.runPromise(harness.symlink("directory", `${harness.root}/directory-link`))
+      await Effect.runPromise(harness.symlink("missing", `${harness.root}/dangling-link`))
+
+      const result = await Effect.runPromise(harness.files.read(`${harness.root}/file-link`))
+      expect(text(result.bytes)).toBe("target content")
+      expect(result.info.type).toBe("file")
+      expect(result.info.size).toBe(bytes("target content").length)
+
+      const directoryError = await failure(harness.files.read(`${harness.root}/directory-link`))
+      expect(directoryError).toBeInstanceOf(WrongKind)
+      expect((directoryError as WrongKind).actual).toBe("directory")
+      expect(await failure(harness.files.read(`${harness.root}/dangling-link`))).toBeInstanceOf(NotFound)
+    })
+
+    check("moves files and removes trees idempotently", async ({ files, root }) => {
+      const source = `${root}/source/file`
+      const destination = `${root}/destination`
+      await Effect.runPromise(files.write(source, bytes("moved")))
+      await Effect.runPromise(files.move(source, destination))
+      expect(text((await Effect.runPromise(files.read(destination))).bytes)).toBe("moved")
+      expect(await failure(files.stat(source))).toBeInstanceOf(NotFound)
+      await Effect.runPromise(files.remove(`${root}/source`))
+      await Effect.runPromise(files.remove(`${root}/source`))
+      expect(await failure(files.stat(`${root}/source`))).toBeInstanceOf(NotFound)
+    })
+  })
+}

packages/core/test/skill.test.ts

@@ -6,11 +6,11 @@ import { Agent } from "@opencode-ai/core/agent"
 import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
 import { LayerNode } from "@opencode-ai/util/effect/layer-node"
 import { Bus } from "@opencode-ai/core/bus"
+import { FSUtil } from "@opencode-ai/util/fs-util"
 import { AbsolutePath } from "@opencode-ai/core/schema"
 import { Skill } from "@opencode-ai/core/skill"
 import { SkillDiscovery } from "@opencode-ai/core/skill/discovery"
 import { FileSystem } from "@opencode-ai/schema/filesystem"
-import { Watcher } from "@opencode-ai/core/filesystem/watcher"
 import { tmpdir } from "./fixture/tmpdir"
 import { testEffect } from "./lib/effect"
 
@@ -25,15 +25,8 @@ const discovery = Layer.succeed(
     },
   }),
 )
-const watcherLayer = Watcher.testLayer
 const it = testEffect(
-  Layer.mergeAll(
-    AppNodeBuilder.build(LayerNode.group([Skill.node, Agent.node, Bus.node]), [
-      [SkillDiscovery.node, discovery],
-      [Watcher.node, watcherLayer],
-    ]),
-    watcherLayer,
-  ),
+  AppNodeBuilder.build(LayerNode.group([Skill.node, Agent.node, Bus.node]), [[SkillDiscovery.node, discovery]]),
 )
 
 function write(directory: string, name: string, description: string) {
@@ -60,24 +53,6 @@ function waitForSkillUpdate() {
   })
 }
 
-function expectSubscription(check: (input: Watcher.WatchInput) => boolean) {
-  return Effect.gen(function* () {
-    const watcher = yield* Watcher.Test
-    expect((yield* watcher.subscriptions()).some(check)).toBe(true)
-  })
-}
-
-function emitAndWait(update: Watcher.Update) {
-  return Effect.gen(function* () {
-    const watcher = yield* Watcher.Test
-    yield* Effect.acquireUseRelease(
-      waitForSkillUpdate(),
-      ({ deferred }) => watcher.emit(update).pipe(Effect.andThen(Deferred.await(deferred)), Effect.timeout("1 second")),
-      ({ fiber }) => Fiber.interrupt(fiber),
-    )
-  })
-}
-
 describe("Skill", () => {
   it.live("publishes updates when skill sources change", () =>
     Effect.gen(function* () {
@@ -223,7 +198,7 @@ metadata:
     ),
   )
 
-  it.live("clears cached skills when sources reload", () =>
+  it.live("invalidates cached skills and publishes updates for watcher changes", () =>
     Effect.acquireRelease(
       Effect.promise(() => tmpdir()),
       (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
@@ -235,155 +210,26 @@ metadata:
             await write(tmp.path, "deploy", "Initial deploy")
           })
 
+          const bus = yield* Bus.Service
           const skill = yield* Skill.Service
           yield* skill.transform((editor) => editor.source({ type: "directory", path: AbsolutePath.make(tmp.path) }))
-          expect((yield* skill.list()).find((item) => item.id === "deploy")?.description).toBe("Initial deploy")
 
+          expect((yield* skill.list()).find((item) => item.name === "deploy")?.description).toBe("Initial deploy")
+
+          const file = path.join(tmp.path, "deploy", "SKILL.md")
           yield* Effect.promise(() => write(tmp.path, "deploy", "Updated deploy"))
-          yield* skill.reload()
+          expect((yield* skill.list()).find((item) => item.name === "deploy")?.description).toBe("Initial deploy")
 
-          expect((yield* skill.list()).find((item) => item.id === "deploy")?.description).toBe("Updated deploy")
-        }),
-      ),
-    ),
-  )
-
-  it.live("reloads project sources created after their missing parent", () =>
-    Effect.acquireRelease(
-      Effect.promise(() => tmpdir()),
-      (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
-    ).pipe(
-      Effect.flatMap((tmp) =>
-        Effect.gen(function* () {
-          const source = path.join(tmp.path, "generated", "skills")
-          const file = path.join(source, "deploy", "SKILL.md")
-          const skill = yield* Skill.Service
-          const bus = yield* Bus.Service
-          yield* skill.transform((editor) => editor.source({ type: "directory", path: AbsolutePath.make(source) }))
-          expect(yield* skill.list()).toEqual([])
-
-          yield* Effect.promise(async () => {
-            await fs.mkdir(path.dirname(file), { recursive: true })
-            await write(source, "deploy", "Deploy production")
-          })
           yield* Effect.acquireUseRelease(
             waitForSkillUpdate(),
             ({ deferred }) =>
               bus
-                .publish(FileSystem.Event.Changed, { file, event: "add" })
+                .publish(FileSystem.Event.Changed, { file, event: "change" })
                 .pipe(Effect.andThen(Deferred.await(deferred)), Effect.timeout("1 second")),
             ({ fiber }) => Fiber.interrupt(fiber),
           )
 
-          expect((yield* skill.list()).map((item) => item.id)).toEqual([Skill.ID.make("deploy")])
-        }),
-      ),
-    ),
-  )
-
-  it.live("watches directory sources for added and changed skills", () =>
-    Effect.acquireRelease(
-      Effect.promise(() => tmpdir()),
-      (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
-    ).pipe(
-      Effect.flatMap((tmp) =>
-        Effect.gen(function* () {
-          yield* Effect.promise(async () => {
-            await fs.mkdir(path.join(tmp.path, "deploy"), { recursive: true })
-            await write(tmp.path, "deploy", "Initial deploy")
-          })
-
-          const skill = yield* Skill.Service
-          yield* skill.transform((editor) => editor.source({ type: "directory", path: AbsolutePath.make(tmp.path) }))
-          expect((yield* skill.list()).map((item) => item.id)).toEqual([Skill.ID.make("deploy")])
-          yield* expectSubscription((input) => input.type === "directory" && input.path === tmp.path)
-
-          const deploy = path.join(tmp.path, "deploy", "SKILL.md")
-          yield* Effect.promise(() => write(tmp.path, "deploy", "Updated deploy"))
-          yield* emitAndWait({ type: "update", path: deploy })
-          expect((yield* skill.list()).find((item) => item.id === "deploy")?.description).toBe("Updated deploy")
-
-          yield* Effect.promise(async () => {
-            await fs.mkdir(path.join(tmp.path, "review"), { recursive: true })
-            await write(tmp.path, "review", "Review changes")
-          })
-          const review = path.join(tmp.path, "review", "SKILL.md")
-          yield* emitAndWait({ type: "create", path: review })
-          expect((yield* skill.list()).map((item) => item.id)).toEqual([
-            Skill.ID.make("deploy"),
-            Skill.ID.make("review"),
-          ])
-
-          yield* Effect.promise(() => fs.rm(path.join(tmp.path, "review"), { recursive: true }))
-          yield* emitAndWait({ type: "delete", path: review })
-          expect((yield* skill.list()).map((item) => item.id)).toEqual([Skill.ID.make("deploy")])
-        }),
-      ),
-    ),
-  )
-
-  it.live("watches canonical directories behind symlinked skills", () =>
-    Effect.acquireRelease(
-      Effect.promise(() => tmpdir()),
-      (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
-    ).pipe(
-      Effect.flatMap((tmp) =>
-        Effect.gen(function* () {
-          const source = path.join(tmp.path, "source")
-          const target = path.join(tmp.path, "target", "bro")
-          const file = path.join(target, "SKILL.md")
-          yield* Effect.promise(async () => {
-            await fs.mkdir(source, { recursive: true })
-            await fs.mkdir(target, { recursive: true })
-            await fs.writeFile(file, "---\nname: bro\ndescription: Initial\n---\n# bro")
-            await fs.symlink(target, path.join(source, "bro"))
-          })
-
-          const skill = yield* Skill.Service
-          yield* skill.transform((editor) => editor.source({ type: "directory", path: AbsolutePath.make(source) }))
-          expect((yield* skill.list()).find((item) => item.id === "bro")?.description).toBe("Initial")
-          yield* expectSubscription((input) => input.type === "directory" && input.path === target)
-
-          yield* Effect.promise(() => fs.writeFile(file, "---\nname: bro\ndescription: Updated\n---\n# bro"))
-          yield* emitAndWait({ type: "update", path: file })
-          expect((yield* skill.list()).find((item) => item.id === "bro")?.description).toBe("Updated")
-        }),
-      ),
-    ),
-  )
-
-  it.live("invalidates symlinked sources when their target changes", () =>
-    Effect.acquireRelease(
-      Effect.promise(() => tmpdir()),
-      (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
-    ).pipe(
-      Effect.flatMap((tmp) =>
-        Effect.gen(function* () {
-          const source = path.join(tmp.path, "source")
-          const first = path.join(tmp.path, "first")
-          const second = path.join(tmp.path, "second")
-          yield* Effect.promise(async () => {
-            await fs.mkdir(path.join(first, "bro"), { recursive: true })
-            await fs.mkdir(path.join(second, "bro"), { recursive: true })
-            await write(first, "bro", "First")
-            await write(second, "bro", "Second")
-            await fs.symlink(first, source)
-          })
-
-          const skill = yield* Skill.Service
-          yield* skill.transform((editor) => editor.source({ type: "directory", path: AbsolutePath.make(source) }))
-          expect((yield* skill.list()).find((item) => item.id === "bro")?.description).toBe("First")
-          yield* expectSubscription((input) => input.type === "directory" && input.path === first)
-          yield* expectSubscription((input) => input.type === "directory" && input.path === tmp.path)
-
-          yield* Effect.promise(async () => {
-            await fs.unlink(source)
-            await fs.symlink(second, source)
-          })
-          yield* emitAndWait({ type: "update", path: source })
-
-          expect((yield* skill.list()).find((item) => item.id === "bro")?.description).toBe("Second")
-          yield* expectSubscription((input) => input.type === "directory" && input.path === second)
+          expect((yield* skill.list()).find((item) => item.name === "deploy")?.description).toBe("Updated deploy")
         }),
       ),
     ),

packages/tui/src/app.tsx

@@ -512,7 +512,7 @@ function App(props: { pair?: DialogPairCredentials }) {
   const terminalTitleEnabled = () => config.data.terminal?.title ?? true
   const copyOnSelectEnabled = () => config.data.terminal?.copy_on_select ?? process.platform !== "win32"
   const pasteSummaryEnabled = () => config.data.prompt?.paste !== "full"
-  const tabsVertical = () => (config.data.tabs?.vertical ?? false) && sessionTabsFitVertically(dimensions().width)
+  const tabsVertical = () => config.data.tabs.layout === "vertical" && sessionTabsFitVertically(dimensions().width)
   const tabsVisible = () =>
     sessionTabs.enabled() && (sessionTabs.tabs().length > 0 || sessionTabs.newTab()) && route.data.type !== "plugin"
 

packages/tui/src/component/dialog-config.tsx

@@ -101,12 +101,11 @@ export const settings: Setting[] = [
     labels: ["current directory", "global"],
   },
   {
-    title: "Vertical",
+    title: "Layout",
     category: "Tabs",
-    path: ["tabs", "vertical"],
-    default: false,
-    values: [false, true],
-    labels: ["off", "on"],
+    path: ["tabs", "layout"],
+    default: "horizontal",
+    values: ["horizontal", "vertical"],
     keywords: ["sidebar", "orientation", "left"],
   },
   {

packages/tui/src/config/index.tsx

@@ -132,8 +132,8 @@ export const Info = Schema.Struct({
       scope: Schema.optional(Schema.Literals(["global", "cwd"])).annotate({
         description: "Share tabs globally or keep a separate set for each working directory",
       }),
-      vertical: Schema.optional(Schema.Boolean).annotate({
-        description: "Show tabs in a left sidebar instead of a horizontal strip",
+      layout: Schema.optional(Schema.Literals(["horizontal", "vertical"])).annotate({
+        description: "Show tabs in a horizontal strip or vertical sidebar",
       }),
     }),
   ).annotate({ description: "Tab strip settings" }),
@@ -194,7 +194,7 @@ export type Resolved = Omit<Info, "attention" | "keybinds" | "leader" | "mouse"
   tabs: {
     enabled: boolean
     scope: "global" | "cwd"
-    vertical?: boolean
+    layout: "horizontal" | "vertical"
   }
 }
 
@@ -230,6 +230,7 @@ export function resolve(input: Info, options: { terminalSuspend: boolean }): Res
       ...input.tabs,
       enabled: input.tabs?.enabled ?? true,
       scope: input.tabs?.scope ?? "cwd",
+      layout: input.tabs?.layout ?? "horizontal",
     },
   }
 }

packages/tui/src/routes/session/index.tsx

@@ -204,7 +204,7 @@ export function Session() {
   const availableWidth = createMemo(
     () =>
       dimensions().width -
-      (config.tabs?.enabled && config.tabs.vertical && sessionTabsFitVertically(dimensions().width)
+      (config.tabs?.enabled && config.tabs.layout === "vertical" && sessionTabsFitVertically(dimensions().width)
         ? SESSION_SIDEBAR_WIDTH
         : 0),
   )

packages/tui/test/config-v2.test.tsx

@@ -18,7 +18,10 @@ test("validates mini replay settings", () => {
 test("validates the session tabs setting", () => {
   const decode = Schema.decodeUnknownSync(Info)
 
-  expect(decode({ tabs: { enabled: true, vertical: true } })).toEqual({ tabs: { enabled: true, vertical: true } })
+  expect(decode({ tabs: { enabled: true, layout: "vertical" } })).toEqual({
+    tabs: { enabled: true, layout: "vertical" },
+  })
+  expect(() => decode({ tabs: { layout: true } })).toThrow()
   expect(() => decode({ tabs: { enabled: "on" } })).toThrow()
 })
 
@@ -39,12 +42,13 @@ test("resolves nested config and keybind defaults", () => {
   expect(config.scroll).toEqual({ speed: 2, acceleration: true })
   expect(config.diffs).toEqual({ view: "split" })
   expect(config.debug).toEqual({ devtools: true })
-  expect(config.tabs).toEqual({ enabled: true, scope: "cwd" })
+  expect(config.tabs).toEqual({ enabled: true, scope: "cwd", layout: "horizontal" })
 })
 
 test("shows resolved tab defaults in settings", () => {
   expect(settings.find((setting) => setting.path.join(".") === "tabs.enabled")?.default).toBe(true)
   expect(settings.find((setting) => setting.path.join(".") === "tabs.scope")?.default).toBe("cwd")
+  expect(settings.find((setting) => setting.path.join(".") === "tabs.layout")?.default).toBe("horizontal")
 })
 
 test("provides config and its host interface", async () => {