feat(exec): ensure MISE_ENV is set in spawned shell when specified via -E flag

[ceelian]

Description

This PR ensures that the MISE_ENV environment variable is properly set in spawned shells when using the mise exec and mise encommand with the -E flag to specify an environment. This solves the issue in the discussion #6928

Changes

• Modified src/cli/exec.rs to check if MISE_ENV is set (via the -E flag) and ensure it's included in the environment variables passed to the spawned shell
• Added new e2e test e2e/cli/test_en_mise_env to verify the behavior

Problem

When using mise exec -E <env> -- <command>, the MISE_ENV variable was not being propagated to the spawned shell environment, making it difficult for scripts to know which mise environment context they're running in. This also applied to the mise -E <env> en command, the command that made me aware of the issue.

Solution

After building the environment with env_with_path(), we now check if MISE_ENV is set (populated by the -E flag) and explicitly add it to the environment map before spawning the shell.

// Ensure MISE_ENV is set in the spawned shell if it was specified via -E flag
if !env::MISE_ENV.is_empty() {
    env.insert("MISE_ENV".to_string(), env::MISE_ENV.join(","));
}

Testing

Added comprehensive e2e test that verifies MISE_ENV is properly set when using mise -E <env> en.

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Note

Ensure MISE_ENV is passed to spawned shells for exec/en when specified via -E, and add e2e tests validating propagation and precedence.

• CLI/Exec:
  • In src/cli/exec.rs, after building env with env_with_path, explicitly insert MISE_ENV (comma-joined) into the spawned shell env when provided via -E.
• E2E Tests:
  • Add e2e/cli/test_en_mise_env covering:
    • MISE_ENV visibility in spawned shell and config discovery for env-specific files.
    • Env var loading/overrides for dev and staging, including multiple envs with order precedence.
    • Behavior without -E (no MISE_ENV, only base config applied).

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[Copilot]

Pull Request Overview

This PR fixes the issue where the MISE_ENV environment variable was not being propagated to spawned shells when using the -E flag to specify an environment. The fix ensures that scripts running in the spawned shell can determine which mise environment context they're operating in.

Key Changes

• Modified src/cli/exec.rs to explicitly set MISE_ENV in the spawned shell environment after building the environment map
• Added comprehensive e2e test suite (test_en_mise_env) to verify the behavior with single and multiple environments

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/cli/exec.rs	Adds logic to insert MISE_ENV into the environment map when it's non-empty, ensuring the variable is available in spawned shells
e2e/cli/test_en_mise_env	Comprehensive test suite with 16 test cases covering single environments, multiple environments, environment-specific config loading, and variable precedence

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[jdx]

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