grep tool searches the whole parent directory when path points to a file

Description

When the grep tool is given a path that points to a file, it silently searches that file's entire parent directory instead.

packages/opencode/src/tool/grep.ts:

const search = FSUtil.resolve(requested)
const info = yield* fs.stat(search).pipe(Effect.catch(() => Effect.succeed(undefined)))
const cwd = info?.type === "Directory" ? search : path.dirname(search)
const result = yield* ripgrep.grep({
  cwd,
  pattern: params.pattern,
  include: params.include,
  limit: 100,
})

The info?.type === "Directory" ? … : path.dirname(search) branch shows the file case is anticipated — but once cwd has been widened to the parent directory nothing narrows the search back down, so ripgrep is invoked over every file in that directory.

The Ripgrep service already supports scoping to a single file. GrepInput declares it and the implementation passes it as ripgrep's path argument (packages/core/src/ripgrep.ts):

export interface GrepInput {
  readonly cwd: string
  readonly pattern: string
  readonly file?: string
  readonly include?: string
  readonly limit: number
  readonly signal?: AbortSignal
}

"--",
input.pattern,
input.file ?? ".",

The v2 tool in packages/core/src/tool/grep.ts:97-104 uses it correctly:

.grep({
  cwd: info?.type === "Directory" ? target : path.dirname(target),
  pattern: input.pattern,
  file: info?.type === "File" ? path.basename(target) : undefined,
  include: input.include,
  limit: input.limit ?? Number.MAX_SAFE_INTEGER,
})

The tool wired into the CLI registry (packages/opencode/src/tool/registry.ts imports GrepTool from ./grep) is the one that omits file. file currently has no callers anywhere in the repo.

Consequences: the model asks about one file and receives matches from every sibling file, the 100-match limit is consumed by unrelated results, and a large directory turns a scoped lookup into a full scan.

Steps to reproduce

1. grep with pattern set to something that appears in several files in a directory.
2. Set path to one specific file in that directory.
3. The output contains matches from the other files as well.

Operating System

Windows 11 (platform independent)