[codex] Handle Ctrl-C for non-TTY unified exec by pakrym-oai · Pull Request #26734 · openai/codex

pakrym-oai · 2026-06-06T04:05:53Z

Why

A long-running unified exec process started with tty: false could not be interrupted via write_stdin: ordinary non-TTY stdin writes are rejected once stdin is closed, but an exact U+0003 payload should still map to a process interrupt. The interrupt should flow through the same process lifecycle path as a real signal so Codex preserves process-reported output and exit metadata instead of fabricating a Ctrl-C exit code or tearing down the session early.

What Changed

Add process/signal to exec-server with ProcessSignal::Interrupt and an empty response.
Add a non-consuming ProcessHandle::signal path for spawned processes; on Unix it sends SIGINT to the process group and leaves terminate/hard-kill unchanged.
Route non-TTY U+0003 write_stdin through process.signal(...) instead of terminate, then let the normal post-write collection path drain output and observe exit.
Add exec-server coverage where a shell trap INT handler prints the signal and exits with its own code.
Add unified exec coverage where a tty: false process traps SIGINT, emits output, and exits with its own code.

Validation

just test -p codex-exec-server exec_process_signal_interrupts_process
just test -p codex-exec-server
just test -p codex-core write_stdin_ctrl_c_interrupts_non_tty_session

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pakrym-oai · 2026-06-08T20:55:43Z

@codex review this

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pakrym-oai · 2026-06-09T00:06:43Z

@codex review this

chatgpt-codex-connector · 2026-06-09T00:09:17Z

Codex Review: Didn't find any major issues. Swish!

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jif-oai

I guess you tried it? Should we add a small prompt in the tool def to encourage the model to use CTRL-C?

jif-oai · 2026-06-09T09:24:00Z


+    pub(super) async fn interrupt(&self) -> Result<(), UnifiedExecError> {
+        match &self.process_handle {
+            ProcessHandle::Local(process_handle) => process_handle


(found by Codex)
This only signals the spawned zsh process group. With unified-exec zsh-fork, approved commands run under EscalateServer outside that group, and the super-exec path still does not forward signal

I'll punt on zsh-fork for now.

jif-oai · 2026-06-09T09:24:41Z

        },
    );
+    router.request(
+        EXEC_SIGNAL_METHOD,


Can we make signal out-of-band or dispatch post-handshake requests concurrently?

I'd like to merge it as it. Signal has the same ordering semantic as write_stdin which we use for sigint in non-tty cases.

jif-oai · 2026-06-09T09:25:17Z

+            ProcessSignal::Interrupt => {
+                #[cfg(unix)]
+                {
+                    crate::process_group::interrupt_process_group(self.process_group_id)


This assumes SIGINT is default and unblocked in the child, but pipe spawn preserves the parent’s signal state. If Codex inherited SIGINT ignored, this returns success while the command keeps running

I think this is fine. Model will recover from the fact the process is still running (by explicitly killing it like it does today)

jif-oai · 2026-06-09T09:25:44Z

-    }
+/// Send SIGINT to a specific process group ID (best-effort).
+pub fn interrupt_process_group(process_group_id: u32) -> io::Result<()> {
+    signal_process_group_id(process_group_id as libc::pid_t, libc::SIGINT).map(|_| ())


(found by Codex)
Can we cover the default SIGINT path too? The pipe waiter maps code() == None to -1, so ordinary Ctrl-C reports exitCode: -1

jif-oai · 2026-06-09T09:26:35Z

+            ProcessSignal::Interrupt => {
+                #[cfg(unix)]
+                if let Some(process_group_id) = self.process_group_id {
+                    return crate::process_group::interrupt_process_group(process_group_id);


I think that for PTYs, this cached group is the shell/session leader, not necessarily the terminal foreground group. But not sure and very nit anyway

pakrym-oai · 2026-06-09T15:06:21Z

I guess you tried it? Should we add a small prompt in the tool def to encourage the model to use CTRL-C?

It doesn't need to be encouraged. That's the default behavior by the model today.

…on-tty-interrupt

jif-oai

lgtm

pakrym-oai marked this pull request as ready for review June 6, 2026 04:15

pakrym-oai requested a review from a team as a code owner June 6, 2026 04:15

chatgpt-codex-connector Bot reviewed Jun 6, 2026

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Comment thread codex-rs/core/src/unified_exec/process_manager.rs Outdated

pakrym-oai force-pushed the pakrym/unified-exec-non-tty-interrupt branch from f765fdc to 5f1f3e3 Compare June 6, 2026 04:41

jif-oai reviewed Jun 8, 2026

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Comment thread codex-rs/core/src/unified_exec/process.rs Outdated

Comment thread codex-rs/core/src/unified_exec/process.rs Outdated

Comment thread codex-rs/core/src/unified_exec/process_manager.rs Outdated

pakrym-oai force-pushed the pakrym/unified-exec-non-tty-interrupt branch 4 times, most recently from 2ce392c to ae2c317 Compare June 8, 2026 18:36

Handle Ctrl-C for non-TTY unified exec

b564da4

pakrym-oai force-pushed the pakrym/unified-exec-non-tty-interrupt branch from ae2c317 to b564da4 Compare June 8, 2026 18:46

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Comment thread codex-rs/utils/pty/src/pipe.rs

Comment thread codex-rs/core/src/unified_exec/process.rs

Comment thread codex-rs/utils/pty/src/process.rs Outdated

pakrym-oai added 2 commits June 8, 2026 14:35

Report unsupported process interrupts

5b5caa9

Avoid expect_err in exec server test

83c0b87

jif-oai reviewed Jun 9, 2026

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pakrym-oai added 3 commits June 9, 2026 08:23

Report SIGINT exit code for unified exec

9ff7581

codex: fix CI failure on PR #26734

e605b38

Merge remote-tracking branch 'origin/main' into pakrym/unified-exec-n…

eb4878b

…on-tty-interrupt

jif-oai approved these changes Jun 9, 2026

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pakrym-oai merged commit f2969f3 into main Jun 9, 2026
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pakrym-oai deleted the pakrym/unified-exec-non-tty-interrupt branch June 9, 2026 22:10

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