/**
 * Session-shell resolution for Windows.
 *
 * `pickShell` (`_shell-pick.ts`) decides the shell *per command* — it inspects
 * each command string and routes PowerShell-looking work to PowerShell, else
 * `cmd.exe`. That keeps individual commands working, but it means the shell the
 * model is *told* about (the system-prompt Environment block) and the shell that
 * actually runs a given command can disagree, and a plain command like
 * `git status` silently lands in `cmd.exe` while `Get-ChildItem` lands in
 * PowerShell. The model has no stable target to write syntax for.
 *
 * This module resolves ONE shell for the whole session and pins it via the
 * `WRONGSTACK_SHELL` env var. Because `WRONGSTACK_SHELL` is already the top
 * precedence in `pickShell`, pinning it makes every command route to the same
 * shell with zero changes to `bash.ts` — and the system-prompt builder can read
 * the same env var to tell the model exactly which shell + syntax to use.
 *
 * Resolution (Windows only — POSIX has no fixed session shell here; `bash.ts`
 * routes through `/bin/bash -c` and honours an explicit `WRONGSTACK_SHELL` as a
 * binary path):
 *   1. A valid user-set `WRONGSTACK_SHELL` (cmd | powershell | pwsh) wins and is
 *      left untouched.
 *   2. Otherwise prefer `pwsh` (PowerShell 7+) when `pwsh.exe` is on PATH.
 *   3. Otherwise `powershell` (Windows PowerShell 5.1).
 *   4. Otherwise `cmd` (only when no PowerShell is installed — effectively never
 *      on a real Windows box).
 *
 * @see {@link ../../docs/configuration.md#windows-shell-selection-wrongstackshell}
 */
import type { BashShell } from './_shell-pick.js';
/**
 * Map a raw `WRONGSTACK_SHELL` value (which may carry a `.exe` suffix or odd
 * casing) to a canonical {@link BashShell}, or `undefined` when it is unset /
 * not a known shell. Mirrors the override parsing in `pickShell`.
 */
export declare function normalizeShell(value: string | undefined): BashShell | undefined;
export interface ResolveSessionShellDeps {
    /**
     * Returns true when `bin` (e.g. `'pwsh.exe'`) resolves on PATH. Injectable so
     * the resolver is unit-testable off-Windows; defaults to `resolveWin32Command`
     * (which itself short-circuits to "not found" when `process.platform` is not
     * win32).
     */
    hasBinary?: ((bin: string) => boolean) | undefined;
}
/**
 * Pure decision: which single shell should the session use on `platform`?
 * Returns `undefined` on non-win32 (no fixed session shell). Does not mutate
 * anything.
 */
export declare function resolveSessionShell(platform: NodeJS.Platform, env: {
    get(key: string): string | undefined;
}, deps?: ResolveSessionShellDeps): BashShell | undefined;
export interface EnsureSessionShellOptions {
    /** Env to read/mutate. Defaults to `process.env`. */
    env?: NodeJS.ProcessEnv | undefined;
    /** Platform override (tests). Defaults to `process.platform`. */
    platform?: NodeJS.Platform | undefined;
    /** Binary-presence probe (tests). Forwarded to {@link resolveSessionShell}. */
    hasBinary?: ((bin: string) => boolean) | undefined;
}
/**
 * Resolve the session shell and pin it into `WRONGSTACK_SHELL` so the bash tool
 * and the system-prompt builder agree on one stable value. Idempotent:
 *
 *   - non-win32 → no-op, returns `undefined`.
 *   - a valid user-set `WRONGSTACK_SHELL` → returned as-is, env left untouched.
 *   - otherwise → resolves, writes the canonical value into the env, returns it.
 *
 * Call this once at process boot, before the system-prompt builder is built.
 */
export declare function ensureSessionShell(opts?: EnsureSessionShellOptions): BashShell | undefined;
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