fix: keep PATH exports on their own line when assembling shell-env.sh

[Arshgill01]

Fixes #3165.

When Python venv (or any enterShell task) re-exports PATH and the parent PATH contains a directory with a space, devenv shell printed bash: export: … not a valid identifier and truncated PATH at the first space.

prepare_shell trims the Nix env script with trim_end(), which removes the newline after eval "${shellHook:-}". Task exports were then appended with no separator, so the first export PATH='…' landed on the same physical line. Outer bash consumed the quotes; eval word-split the PATH value at spaces.

Changes

• Add push_shell_fragment, which inserts a newline before appending a non-empty fragment.
• Use it wherever the env script is concatenated with task exports/messages (prepare_shell, PTY/reload shell-env.sh, direnv export).
• Empty fragments remain a no-op, so projects without venv/task exports are unchanged.

Tests

• Unit: assemble a trimmed env script plus a PATH export containing Some App, assert the export is on its own line, then bash the result and check PATH is not truncated.
• Integration: tests/shell-path-spaces — PATH with a space + a venv-like enterShell PATH export; --shell zsh writes .devenv/shell-env.sh (the glued assembly) and devenv shell -- covers the non-interactive path.

No competing open PR for #3165.

Test plan

• Standalone reproduction: glued eval "${shellHook:-}"export PATH='…Some App…' produces not a valid identifier and truncates PATH; with a newline separator, bash sources cleanly and PATH keeps the space-containing dir.
• cargo nextest run -p devenv trimmed_shell_env push_shell_fragment
• devenv-run-tests run tests --only shell-path-spaces
• Manual: PATH="/tmp/Some App/bin:$PATH" devenv shell in a project with languages.python.venv.enable = true — no export errors, echo "$PATH" still contains Some App.

[github-actions]

🔍 Suggested Reviewers

Based on git blame analysis of the changed lines, the following contributors have significant experience with the modified code:

• @sandydoo - 50.0% of changed lines (8 lines)
• @domenkozar - 50.0% of changed lines (8 lines)

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Last updated: 2026-09-30T04:38:50.497Z

[Arshgill01]

Rebased onto latest cachix/devenv main (was ~13 commits behind). The push_shell_fragment / PATH-with-spaces fix is unchanged; the changelog entry now lives under 2.3.2 (unreleased) so it stays with the current unreleased notes rather than the released 2.3.1 section.

[Arshgill01]

Still ready for review (bundled)

Gentle weekly nudge — still no maintainer feedback on the open Arshgill01 set. All MERGEABLE (rebasing onto latest main now if needed):

PR	Summary
#3166	PATH spaces in shell-env.sh (Fixes #3165)
#3156	GC-root concurrent NotFound TOCTOU leftover from #3133
#3152	Reuse running process manager for process deps (Fixes #3137)
#2978	process-compose list / wait lifecycle commands

Happy to address review feedback on any of them.