Use subprocess.Popen for background jobs to survive TUI exit

asyncio's SubprocessTransport sends SIGKILL to child processes during
event loop cleanup, killing the gniza bash wrapper when the TUI exits.
Switch to subprocess.Popen which has no such cleanup behavior, allowing
backup jobs to continue running after the TUI is closed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tui/backend.py

@@ -1,5 +1,6 @@
 import asyncio
 import os
+import subprocess
 from pathlib import Path
 
 
@@ -24,24 +25,22 @@ async def run_cli(*args: str) -> tuple[int, str, str]:
     return proc.returncode or 0, stdout.decode(), stderr.decode()
 
 
-async def start_cli_process(*args: str, log_file: str | None = None) -> asyncio.subprocess.Process:
+def start_cli_background(*args: str, log_file: str) -> subprocess.Popen:
+    """Start a CLI process that survives TUI exit.
+
+    Uses subprocess.Popen directly (not asyncio) so there is no
+    SubprocessTransport that would SIGKILL the child on event-loop cleanup.
+    """
     cmd = [_gniza_bin(), "--cli"] + list(args)
-    if log_file:
-        fh = open(log_file, "w")
-        proc = await asyncio.create_subprocess_exec(
-            *cmd,
-            stdout=fh,
-            stderr=asyncio.subprocess.STDOUT,
-            start_new_session=True,
-        )
-        fh.close()
-        return proc
-    return await asyncio.create_subprocess_exec(
-        *cmd,
-        stdout=asyncio.subprocess.PIPE,
-        stderr=asyncio.subprocess.STDOUT,
+    fh = open(log_file, "w")
+    proc = subprocess.Popen(
+        cmd,
+        stdout=fh,
+        stderr=subprocess.STDOUT,
         start_new_session=True,
     )
+    fh.close()
+    return proc
 
 
 async def stream_cli(callback, *args: str) -> int:

tui/jobs.py

@@ -2,6 +2,7 @@ import asyncio
 import json
 import os
 import signal
+import subprocess
 import uuid
 from dataclasses import dataclass, field
 from datetime import datetime
@@ -9,7 +10,7 @@ from pathlib import Path
 
 from textual.message import Message
 
-from tui.backend import start_cli_process
+from tui.backend import start_cli_background
 
 MAX_OUTPUT_LINES = 10_000
 FINISHED_JOB_TTL_HOURS = 24
@@ -42,7 +43,7 @@ class Job:
     finished_at: datetime | None = None
     return_code: int | None = None
     output: list[str] = field(default_factory=list)
-    _proc: asyncio.subprocess.Process | None = field(default=None, repr=False)
+    _proc: subprocess.Popen | None = field(default=None, repr=False)
     _pid: int | None = field(default=None, repr=False)
     _pgid: int | None = field(default=None, repr=False)
     _reconnected: bool = field(default=False, repr=False)
@@ -80,7 +81,7 @@ class JobManager:
     async def run_job(self, app, job: Job, *cli_args: str) -> int:
         log_path = _work_dir() / f"gniza-job-{job.id}.log"
         job._log_file = str(log_path)
-        proc = await start_cli_process(*cli_args, log_file=str(log_path))
+        proc = start_cli_background(*cli_args, log_file=str(log_path))
         job._proc = proc
         job._pid = proc.pid
         try:
@@ -89,10 +90,9 @@ class JobManager:
             job._pgid = None
         self._save_registry()
         try:
-            # Wait for process and tail log file concurrently
-            wait_task = asyncio.create_task(proc.wait())
+            # Poll process and tail log file
             with open(log_path, "r") as f:
-                while not wait_task.done():
+                while proc.poll() is None:
                     line = f.readline()
                     if line:
                         text = line.rstrip("\n")
@@ -130,7 +130,7 @@ class JobManager:
         return job.return_code if job.return_code is not None else 1
 
     @staticmethod
-    def _kill_process_group(proc: asyncio.subprocess.Process) -> None:
+    def _kill_process_group(proc: subprocess.Popen) -> None:
         try:
             pgid = os.getpgid(proc.pid)
             os.killpg(pgid, signal.SIGKILL)