fix(pty): process output alongside wake events

[akbash-bot]

Summary

• process PTY read and write readiness even when the actor wake FD is ready in the same poll
• add deterministic simultaneous wake/read/write regression coverage
• document the background-pane output fix

Checks

• cargo test pty::actor::unix::tests -- --nocapture
• cargo clippy --all-targets --locked -- -D warnings
• just windows-lint
• integration asset, plugin marketplace, and maintenance-script suites
• cargo nextest run --locked -E 'all() - test(live_server_holds_one_pty_master_fd_per_pane) - test(metadata_clear_only_without_ttl_does_not_extend_old_ttl)' (3248 passed; the handoff PID-discovery test fails identically on the base commit in this host, and the timing test passes in isolation)
• live restored-session reproduction: a fresh --no-focus pane surfaced command output in 321 ms while the active workspace remained unchanged

refs #2449

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 9ad7d264-68d7-4bb5-a5a3-267c9413fb32

📥 Commits

Reviewing files that changed from the base of the PR and between 69a07fd and 1cb8565.

📒 Files selected for processing (2)

• docs/next/CHANGELOG.md
• src/pty/actor/unix.rs

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📝 Walkthrough

Walkthrough

The PTY actor now processes wake, read, and write readiness in one cycle. Tests cover simultaneous readiness, and the changelog records reliable pane output for fresh background workspaces.

Changes

PTY readiness handling

Layer / File(s)	Summary
Readiness processing src/pty/actor/unix.rs	run delegates readiness handling to handle_poll_readiness. The handler drains wake notifications, processes PTY reads, flushes writes, and stops on relevant failures.
Readiness validation and release note src/pty/actor/unix.rs, docs/next/CHANGELOG.md	Tests retain the wake writer and verify simultaneous wake, PTY read, and PTY write readiness. The changelog records the pane output fix.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description clearly explains the PTY fix, regression coverage, documentation change, and validation results.
Title check	✅ Passed	The title clearly and concisely describes the main change: processing PTY output alongside wake events.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch akbash/2449-no-focus-pane-input

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