diff --git a/cron/jobs.py b/cron/jobs.py
index 566db1e6dbc..a7c87d223e1 100644
--- a/cron/jobs.py
+++ b/cron/jobs.py
@@ -72,6 +72,65 @@ def _apply_skill_fields(job: Dict[str, Any]) -> Dict[str, Any]:
     return normalized
 
 
+def _coerce_job_text(value: Any, fallback: str = "") -> str:
+    """Coerce legacy/hand-edited nullable cron fields to strings for readers."""
+    if value is None:
+        return fallback
+    return str(value)
+
+
+def _schedule_display_for_job(job: Dict[str, Any]) -> str:
+    display = _coerce_job_text(job.get("schedule_display")).strip()
+    if display:
+        return display
+
+    schedule = job.get("schedule")
+    if isinstance(schedule, dict):
+        for key in ("display", "value", "expr", "run_at"):
+            text = _coerce_job_text(schedule.get(key)).strip()
+            if text:
+                return text
+    elif schedule is not None:
+        return str(schedule)
+
+    return "?"
+
+
+def _normalize_job_record(job: Dict[str, Any]) -> Dict[str, Any]:
+    """Return a read-safe cron job shape for UI/API/tool/scheduler consumers.
+
+    Older or hand-edited jobs can have nullable fields like ``prompt``,
+    ``name``, or ``schedule_display``.  Keep storage untouched on read, but
+    ensure consumers never crash while formatting or running those records.
+    """
+    normalized = _apply_skill_fields(job)
+    job_id = _coerce_job_text(normalized.get("id"), "unknown")
+    prompt = _coerce_job_text(normalized.get("prompt"))
+    normalized["id"] = job_id
+    normalized["prompt"] = prompt
+
+    name = _coerce_job_text(normalized.get("name")).strip()
+    if not name:
+        script = _coerce_job_text(normalized.get("script")).strip()
+        label_source = (
+            prompt
+            or (normalized["skills"][0] if normalized.get("skills") else "")
+            or script
+            or job_id
+            or "cron job"
+        )
+        name = label_source[:50].strip() or "cron job"
+    normalized["name"] = name
+    normalized["schedule_display"] = _schedule_display_for_job(normalized)
+
+    state = _coerce_job_text(normalized.get("state")).strip()
+    if not state:
+        state = "scheduled" if normalized.get("enabled", True) else "paused"
+    normalized["state"] = state
+
+    return normalized
+
+
 def _secure_dir(path: Path):
     """Set directory to owner-only access (0700). No-op on Windows."""
     try:
@@ -533,11 +592,12 @@ def create_job(
     else:
         context_from = None
 
-    label_source = (prompt or (normalized_skills[0] if normalized_skills else None) or (normalized_script if normalized_no_agent else None)) or "cron job"
+    prompt_text = _coerce_job_text(prompt)
+    label_source = (prompt_text or (normalized_skills[0] if normalized_skills else None) or (normalized_script if normalized_no_agent else None)) or "cron job"
     job = {
         "id": job_id,
         "name": name or label_source[:50].strip(),
-        "prompt": prompt,
+        "prompt": prompt_text,
         "skills": normalized_skills,
         "skill": normalized_skills[0] if normalized_skills else None,
         "model": normalized_model,
@@ -581,13 +641,13 @@ def get_job(job_id: str) -> Optional[Dict[str, Any]]:
     jobs = load_jobs()
     for job in jobs:
         if job["id"] == job_id:
-            return _apply_skill_fields(job)
+            return _normalize_job_record(job)
     return None
 
 
 def list_jobs(include_disabled: bool = False) -> List[Dict[str, Any]]:
     """List all jobs, optionally including disabled ones."""
-    jobs = [_apply_skill_fields(j) for j in load_jobs()]
+    jobs = [_normalize_job_record(j) for j in load_jobs()]
     if not include_disabled:
         jobs = [j for j in jobs if j.get("enabled", True)]
     return jobs
@@ -637,7 +697,7 @@ def update_job(job_id: str, updates: Dict[str, Any]) -> Optional[Dict[str, Any]]
 
         jobs[i] = updated
         save_jobs(jobs)
-        return _apply_skill_fields(jobs[i])
+        return _normalize_job_record(jobs[i])
     return None
 
 
diff --git a/cron/scheduler.py b/cron/scheduler.py
index df5fdfbb629..7fda096031a 100644
--- a/cron/scheduler.py
+++ b/cron/scheduler.py
@@ -845,7 +845,7 @@ def _build_job_prompt(job: dict, prerun_script: Optional[tuple] = None) -> str:
             result is used for prompt injection. When omitted, the script
             (if any) runs inline as before.
     """
-    prompt = job.get("prompt", "")
+    prompt = str(job.get("prompt") or "")
     skills = job.get("skills")
 
     # Run data-collection script if configured, inject output as context.
@@ -933,6 +933,8 @@ def _build_job_prompt(job: dict, prerun_script: Optional[tuple] = None) -> str:
     if skills is None:
         legacy = job.get("skill")
         skills = [legacy] if legacy else []
+    elif isinstance(skills, str):
+        skills = [skills]
 
     skill_names = [str(name).strip() for name in skills if str(name).strip()]
     if not skill_names:
@@ -1015,7 +1017,7 @@ def run_job(job: dict) -> tuple[bool, str, str, Optional[str]]:
         Tuple of (success, full_output_doc, final_response, error_message)
     """
     job_id = job["id"]
-    job_name = job["name"]
+    job_name = str(job.get("name") or job.get("prompt") or job_id or "cron job")
 
     # ---------------------------------------------------------------
     # no_agent short-circuit — the script IS the job, no LLM involvement.
diff --git a/tests/cron/test_jobs.py b/tests/cron/test_jobs.py
index 0405f997b14..af42ca444b2 100644
--- a/tests/cron/test_jobs.py
+++ b/tests/cron/test_jobs.py
@@ -207,6 +207,26 @@ class TestJobCRUD:
         jobs = list_jobs()
         assert len(jobs) == 2
 
+    def test_list_jobs_normalizes_partial_legacy_records(self, tmp_cron_dir):
+        save_jobs([
+            {
+                "id": "abc123deadbe",
+                "name": None,
+                "prompt": None,
+                "schedule_display": None,
+                "schedule": {"kind": "interval", "minutes": 60, "display": "every 60m"},
+                "enabled": True,
+            }
+        ])
+
+        jobs = list_jobs()
+
+        assert jobs[0]["id"] == "abc123deadbe"
+        assert jobs[0]["name"] == "abc123deadbe"
+        assert jobs[0]["prompt"] == ""
+        assert jobs[0]["schedule_display"] == "every 60m"
+        assert jobs[0]["state"] == "scheduled"
+
     def test_remove_job(self, tmp_cron_dir):
         job = create_job(prompt="Temp job", schedule="30m")
         assert remove_job(job["id"]) is True
diff --git a/tests/cron/test_scheduler.py b/tests/cron/test_scheduler.py
index ce213a9f396..e0cb1cc155e 100644
--- a/tests/cron/test_scheduler.py
+++ b/tests/cron/test_scheduler.py
@@ -1788,6 +1788,11 @@ class TestBuildJobPromptSilentHint:
         result = _build_job_prompt(job)
         assert "[SILENT]" in result
 
+    def test_hint_present_when_legacy_prompt_is_null(self):
+        job = {"id": "abc123deadbe", "name": None, "prompt": None}
+        result = _build_job_prompt(job)
+        assert "[SILENT]" in result
+
     def test_delivery_guidance_present(self):
         """Cron hint tells agents their final response is auto-delivered."""
         job = {"prompt": "Generate a report"}
diff --git a/tests/tools/test_cronjob_tools.py b/tests/tools/test_cronjob_tools.py
index ab6f8eef08a..ccb01edc56b 100644
--- a/tests/tools/test_cronjob_tools.py
+++ b/tests/tools/test_cronjob_tools.py
@@ -122,6 +122,28 @@ class TestUnifiedCronjobTool:
         assert listing["jobs"][0]["name"] == "Server Check"
         assert listing["jobs"][0]["state"] == "scheduled"
 
+    def test_list_handles_partial_legacy_job_records(self):
+        from cron.jobs import save_jobs
+
+        save_jobs([
+            {
+                "id": "abc123deadbe",
+                "name": None,
+                "prompt": None,
+                "schedule_display": None,
+                "schedule": {"kind": "interval", "minutes": 60, "display": "every 60m"},
+                "repeat": {"times": None, "completed": 0},
+                "enabled": True,
+            }
+        ])
+
+        listing = json.loads(cronjob(action="list"))
+
+        assert listing["success"] is True
+        assert listing["jobs"][0]["name"] == "abc123deadbe"
+        assert listing["jobs"][0]["prompt_preview"] == ""
+        assert listing["jobs"][0]["schedule"] == "every 60m"
+
     def test_pause_and_resume(self):
         created = json.loads(cronjob(action="create", prompt="Check", schedule="every 1h"))
         job_id = created["job_id"]
diff --git a/tools/cronjob_tools.py b/tools/cronjob_tools.py
index b4cc4f69ecc..c9d0e9ade7e 100644
--- a/tools/cronjob_tools.py
+++ b/tools/cronjob_tools.py
@@ -220,18 +220,20 @@ def _validate_cron_script_path(script: Optional[str]) -> Optional[str]:
 
 
 def _format_job(job: Dict[str, Any]) -> Dict[str, Any]:
-    prompt = job.get("prompt", "")
+    prompt = str(job.get("prompt") or "")
     skills = _canonical_skills(job.get("skill"), job.get("skills"))
+    job_id = str(job.get("id") or "unknown")
+    name = str(job.get("name") or prompt[:50] or (skills[0] if skills else "") or job_id or "cron job")
     result = {
-        "job_id": job["id"],
-        "name": job["name"],
+        "job_id": job_id,
+        "name": name,
         "skill": skills[0] if skills else None,
         "skills": skills,
         "prompt_preview": prompt[:100] + "..." if len(prompt) > 100 else prompt,
         "model": job.get("model"),
         "provider": job.get("provider"),
         "base_url": job.get("base_url"),
-        "schedule": job.get("schedule_display"),
+        "schedule": job.get("schedule_display") or "?",
         "repeat": _repeat_display(job),
         "deliver": job.get("deliver", "local"),
         "next_run_at": job.get("next_run_at"),