docs(environments): describe the Linux sleep inhibitor as it now runs

[Hmbown]

Summary

Devin's analysis note on #6372: docs/ENVIRONMENTS.md still showed the Linux inhibitor as systemd-inhibit … sleep infinity, while since #6372 the command is cat reading a pipe the guard holds and the release is that pipe closing. The guide now says so, and states that nothing is left behind.

No-Issue: docs follow-up to #6372's review note; one line of the environment guide.

Testing

Docs only; no code or generated file changes. CI's light-change path covers the markdown checks.

• cargo fmt --all -- --check (n/a, no Rust changes)
• cargo clippy --workspace --all-targets --all-features --locked (n/a)
• cargo test --workspace --all-features --locked (n/a)

Checklist

• This PR adds a new layer/module/abstraction — it names or deletes the layer it replaces (n/a)
• Updated docs or comments as needed
• Added or updated tests where relevant (n/a)
• Verified TUI behavior manually if UI changes (n/a)
• Harvested/co-authored credit uses a GitHub numeric noreply address (n/a)

🤖 Generated with Claude Code

https://claude.ai/code/session_0134iUMxmGuXiG1LzPgfZVnv

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Generated by Claude Code

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-21T03:10:09.463206Z	c6a7075	Draft marked ready

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[claude]

Claude finished @Hmbown's task in 42s —— View job

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Review: docs(environments) — Linux sleep inhibitor description

• Gather context (PR diff, docs/ENVIRONMENTS.md, crates/tui/src/sleep_guard.rs)
• Verify the doc change against the actual implementation
• Post findings

Summary

This is a documentation-only fix (+5/-3, single file) correcting docs/ENVIRONMENTS.md to match the Linux sleep-inhibitor implementation that shipped in #6372.

I cross-checked the updated text against crates/tui/src/sleep_guard.rs:

• The command is accurately described: systemd-inhibit --what=idle --why="Codewhale turn in flight" --mode=block cat, matching start_inhibitor() (sleep_guard.rs:106-117).
• The explanation that cat reads a pipe held by the guard, and that dropping the guard closes the pipe so cat exits on EOF and systemd-inhibit follows, matches both the module doc comment (sleep_guard.rs:36-39) and the spawn() implementation (stdin piped, never written to; kill_on_drop(true)).
• The claim "nothing is left behind" is backed by the existing test a_released_guard_leaves_no_grandchild_behind (sleep_guard.rs:188-214), which explicitly checks that grandchild processes don't outlive the guard.
• Surrounding scope statements (idle-only assertion, headless hosts never hold it, Windows unimplemented and why) are unchanged and remain consistent with the module's stated scope (sleep_guard.rs:10-25).

No correctness, provider/model-routing, reuse, test-coverage, or security concerns — this only touches prose in a markdown file. No code changes to review. I don't have anything to flag here; the update accurately reflects current behavior.

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.