fix(client): avoid abort on terminal hangup

[akbash-bot]

Summary

• make terminal restoration fully best-effort when the outer PTY has hung up
• cover real PTY-master closure and verify the detached server survives
• keep direct-SIGHUP and server-EOF restoration behavior covered

Checks

• cargo test --test client_mode client_exits_cleanly_when_terminal_hangs_up -- --exact
• cargo test --test client_mode client_restores_terminal_on_sighup -- --exact
• cargo test --test client_mode client_restores_terminal_on_server_eof -- --exact
• just lint
• 3,240 Rust tests passed (one unrelated live-handoff harness test skipped because this issue's required external CARGO_TARGET_DIR is outside its hardcoded checkout-root process scan)
• just windows-lint
• integration asset, plugin marketplace, and maintenance script tests
• live PTY hangup: SIGABRT/core before; exit 0 with server surviving after

refs #2424

[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: 345bc42e-fdb0-4c85-8b47-22abfb49f27e

📥 Commits

Reviewing files that changed from the base of the PR and between c6885a2 and af7c05e.

📒 Files selected for processing (1)

• tests/client_mode.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• tests/client_mode.rs

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📝 Walkthrough

Walkthrough

The client now uses fallible terminal restoration. Unix-only client-mode tests detect PTY closure, verify clean client exit, and confirm server responsiveness.

Changes

Terminal hangup handling

Layer / File(s)	Summary
Fallible terminal restoration src/client/mod.rs	restore_terminal_state now calls ratatui::try_restore() and ignores the returned error.
PTY closure integration test tests/client_mode.rs	The tests run on Unix, distinguish SIGHUP handling from terminal-window closure, detect client attachment through nonblocking PTY output, simulate PTY closure, verify client exit, and confirm server ping responsiveness.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• herdrdev/herdr#2041: Updates client terminal restoration and extends PTY and SIGHUP closure coverage.
• herdrdev/herdr#2347: Modifies client terminal-state restoration and adds guarded restoration logic.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the client terminal hangup fix, which is the main change in the pull request.
Description check	✅ Passed	The description accurately summarizes the terminal restoration fix, added PTY coverage, validation checks, and expected behavior.
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/2424-hungup-stderr

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[coderabbitai]

Actionable comments posted: 1

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 12a5ae19-61d9-4b2f-ae6e-2c598a20a545

📥 Commits

Reviewing files that changed from the base of the PR and between 3825c0c and c6885a2.

📒 Files selected for processing (2)

• src/client/mod.rs
• tests/client_mode.rs

[greptile-apps]

Greptile Summary

The PR prevents terminal restoration from aborting a client after its outer PTY hangs up while preserving the detached server.

• Replaces the panicking terminal restoration call with its fallible, best-effort counterpart.
• Adds an end-to-end Unix PTY hangup test that verifies clean client exit and server survival.
• Retains coverage for direct SIGHUP and server-EOF restoration paths.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete blocking or non-blocking defects identified in the changed behavior.

The production change is narrowly scoped to suppressing restoration failure after terminal hangup, and the new integration coverage exercises the intended client-exit and detached-server-survival behavior.

Important Files Changed

Filename	Overview
src/client/mod.rs	Makes ratatui terminal restoration fallible and best-effort so teardown cannot abort when the outer PTY is already unwritable.
tests/client_mode.rs	Gates the Unix-specific integration suite appropriately and adds real PTY-master closure coverage for clean client exit and server survival.

_{Reviews (1): Last reviewed commit: "test(client): gate PTY integration on un..." | Re-trigger Greptile}