diff --git a/CHANGELOG.md b/CHANGELOG.md
index 17246ea..a8cfec1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
+## [Unreleased]
+
+### Fixed
+
+- 🔒 **A finished process's result could vanish before a slow caller ever read it** — a finished process's in-memory record (and its result) was deleted 300s after completion regardless of whether anyone had actually retrieved it yet. A caller whose own dispatch loop stalls past that window would come back to `{"detail": "Process not found"}` -- permanent, silent loss of a command that actually succeeded, with no way to distinguish "still running" from "result is gone." Now tracks `delivered_at` separately from `finished_at`: undelivered results get a much longer grace period (`OPEN_TERMINAL_PROCESS_UNDELIVERED_EXPIRY`, default 30 minutes), delivered results keep the original short one (`OPEN_TERMINAL_PROCESS_EXPIRY`, default 5 minutes, unchanged default), since the caller already has what it needs.
+
 ## [0.11.34] - 2026-04-08
 
 ### Added
diff --git a/open_terminal/env.py b/open_terminal/env.py
index b7bd1d1..f0bfe82 100644
--- a/open_terminal/env.py
+++ b/open_terminal/env.py
@@ -107,6 +107,30 @@ def _resolve_file_env(var: str, default: str = "") -> str:
     )
 )
 
+# How long (in seconds) to keep a finished process's in-memory record
+# AFTER its result has been successfully delivered at least once via
+# GET /execute/{id}/status. Short is fine here -- the caller already has
+# what it needs.
+PROCESS_EXPIRY: float = float(
+    os.environ.get(
+        "OPEN_TERMINAL_PROCESS_EXPIRY",
+        config.get("process_expiry", 300),  # 5 minutes
+    )
+)
+
+# How long (in seconds) to keep a finished process's in-memory record if
+# NOBODY has successfully polled its status yet. Deliberately much longer
+# than PROCESS_EXPIRY: a caller whose own dispatch loop stalls still
+# needs the result to be there when it eventually recovers and asks.
+# Expiring on the same short window as a delivered result turns a
+# recoverable caller-side hang into a permanent, silent loss.
+PROCESS_UNDELIVERED_EXPIRY: float = float(
+    os.environ.get(
+        "OPEN_TERMINAL_PROCESS_UNDELIVERED_EXPIRY",
+        config.get("process_undelivered_expiry", 1800),  # 30 minutes
+    )
+)
+
 # Minimum interval (in seconds) between log flushes during command execution.
 # 0 (default) = flush after every chunk (current behaviour).
 # Setting this to e.g. 1.0 reduces I/O pressure on high-output commands.
diff --git a/open_terminal/main.py b/open_terminal/main.py
index 01c0796..6f6b150 100644
--- a/open_terminal/main.py
+++ b/open_terminal/main.py
@@ -24,7 +24,7 @@
 from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
 from pydantic import BaseModel, Field
 
-from open_terminal.env import API_KEY, BINARY_FILE_MIME_PREFIXES, CORS_ALLOWED_ORIGINS, ENABLE_NOTEBOOKS, ENABLE_SYSTEM_PROMPT, ENABLE_TERMINAL, EXECUTE_DESCRIPTION, EXECUTE_TIMEOUT, FILE_BROWSER_ROOT, LOG_DIR, MAX_TERMINAL_SESSIONS, MULTI_USER, OPEN_TERMINAL_INFO, PROCESS_LOG_RETENTION, SESSION_CWD_TTL, SYSTEM_PROMPT, TERMINAL_TERM
+from open_terminal.env import API_KEY, BINARY_FILE_MIME_PREFIXES, CORS_ALLOWED_ORIGINS, ENABLE_NOTEBOOKS, ENABLE_SYSTEM_PROMPT, ENABLE_TERMINAL, EXECUTE_DESCRIPTION, EXECUTE_TIMEOUT, FILE_BROWSER_ROOT, LOG_DIR, MAX_TERMINAL_SESSIONS, MULTI_USER, OPEN_TERMINAL_INFO, PROCESS_EXPIRY, PROCESS_LOG_RETENTION, PROCESS_UNDELIVERED_EXPIRY, SESSION_CWD_TTL, SYSTEM_PROMPT, TERMINAL_TERM
 from open_terminal.utils.runner import PipeRunner, ProcessRunner, create_runner
 from open_terminal.utils.fs import UserFS
 
@@ -304,11 +304,11 @@ class BackgroundProcess:
     exit_code: Optional[int] = None
     log_task: Optional[asyncio.Task] = field(default=None, repr=False)
     finished_at: Optional[float] = field(default=None, repr=False)
+    delivered_at: Optional[float] = field(default=None, repr=False)
     log_path: Optional[str] = field(default=None, repr=False)
 
 
 _processes: dict[str, BackgroundProcess] = {}
-_EXPIRY_SECONDS = 300  # auto-clean finished processes after 5 min
 
 
 # ---------------------------------------------------------------------------
@@ -353,15 +353,26 @@ def _set_session_cwd(session_id: str | None, path: str):
 def _cleanup_expired():
     """Remove finished processes that have expired.
 
+    Two different grace periods: a process whose finished status has been
+    successfully delivered to a caller at least once only needs
+    PROCESS_EXPIRY (short -- the caller already has the result). A
+    process nobody has successfully polled yet gets
+    PROCESS_UNDELIVERED_EXPIRY instead (much longer), so a caller whose
+    own dispatch loop stalls doesn't come back to find its result
+    already gone.
+
     Also deletes log files older than *LOG_RETENTION_SECONDS*.
     """
     now = time.time()
-    expired = [
-        process_id
-        for process_id, background_process in _processes.items()
-        if background_process.finished_at
-        and now - background_process.finished_at > _EXPIRY_SECONDS
-    ]
+    expired = []
+    for process_id, background_process in _processes.items():
+        if not background_process.finished_at:
+            continue
+        if background_process.delivered_at is not None:
+            if now - background_process.delivered_at > PROCESS_EXPIRY:
+                expired.append(process_id)
+        elif now - background_process.finished_at > PROCESS_UNDELIVERED_EXPIRY:
+            expired.append(process_id)
     for process_id in expired:
         bp = _processes.pop(process_id)
         # Delete the log file if it has exceeded the retention period.
@@ -1201,6 +1212,12 @@ async def execute(
         background_process.log_path, offset=0, tail=tail
     )
 
+    if background_process.status != "running" and background_process.delivered_at is None:
+        # A synchronous wait that returned a finished result already
+        # delivered it to the caller -- same accounting as the dedicated
+        # status endpoint below.
+        background_process.delivered_at = time.time()
+
     return {
         "id": process_id,
         "command": request.command,
@@ -1259,6 +1276,12 @@ async def get_status(
         background_process.log_path, offset=offset, tail=tail
     )
 
+    if background_process.status != "running" and background_process.delivered_at is None:
+        # First successful read of a finished process's status -- from
+        # here on the short PROCESS_EXPIRY grace period applies instead
+        # of PROCESS_UNDELIVERED_EXPIRY.
+        background_process.delivered_at = time.time()
+
     return {
         "id": background_process.id,
         "command": background_process.command,