feat!: replace get_job/job_history with describe_job/query_job_events (#4130)

A 1M-row column refresh over 200 fragments produced no visible result,
and the client could only ever say `"running"`. Everything needed to
diagnose it already existed server-side — the job registry records a
`claim`/`claim_complete` pair per fragment carrying `rows_processed` —
but none of it was reachable.

## Before

Four ways to ask about a job, none of which told you much.

```python
job = table.refresh_column_async("embedding")
job.status()               # "running". That was the entire debug surface.
db.get_job(job_id)         # state, and a spec. No result, no progress.
db.job_history(job_id)     # raw record batches, no limit, no filter
db.job(job_id)             # a handle that knew nothing
```

## After

Open a job the way you open a table; the handle answers everything.

```python
job = db.open_job(job_id)      # raises JobNotFoundError if there is no such job
```

```python
>>> print(job)
Job(
    id='job-1',
    state='failed',
    job_type='refresh_column',
    creation_ms=1757000000000,
    spec={
        "column": "embedding",
        "num_workers": 4
    },
    failure=JobFailureInfo(phase='execute', message='worker died', retryable=True),
)
```

Individual fields are there too — `job.state`, `job.job_type`,
`job.creation_ms`, `job.spec`, `job.result`, `job.failure` — and
`job.result` carries `rows_assigned` / `rows_failed` as soon as the job
succeeds, with no `wait()` required.

Per-fragment progress *while it is still running*:

```python
done = job.events(filter="state = 'claim_complete'", limit=10_000)
done.column("rows_processed").to_pylist()      # [5000, 5000, ...]
```

The handle an async action returns is the same object, one `refresh()`
away:

```python
job = table.refresh_column_async("embedding")
job.refresh()
job.state, job.result
```

TypeScript is the same experience, down to `console.log`:

```ts
const job = await db.openJob(jobId);   // rejects if there is no such job
console.log(job);                      // same multi-line layout
job.state; job.jobType; job.spec; job.result; job.failure;
const done = await job.events({ filter: "state = 'claim_complete'", limit: 10_000 });
```

## Why each piece matters

- **A result without waiting.** `rows_assigned` / `rows_failed` used to
live only on the terminal result, so a job that never terminated
reported nothing at all.
- **`limit`.** The server caps event rows at 1000 and truncates without
saying so, which silently hid most of a 200-fragment job's history.
- **`filter`.** `claim_complete` rows carry per-claim `rows_processed` —
the only progress signal that exists mid-flight.
- **Events outlive the worker.** They live in the job registry, not in
pod logs that vanish with the pod.
- **One place to ask.** `open_job` replaces `describe_job`,
`query_job_events` and `job`, so a question about a job has one answer
instead of one per calling location.
- **A missing job is an error, not a `None`.** The common case is a job
id copied out of a log, where absence is the surprise worth raising —
and it matches `open_table`.
- **Printing is the debug surface.** Every field on its own line, JSON
payloads keeping their structure. An unrefreshed handle stays on one
line, because there is nothing to lay out.
- **In-process jobs say so.** A local refresh reports `state` and leaves
the rest null rather than inventing fields it has no record for.

`list_jobs` and `cancel_job` stay as they were: one lists, the other is
a one-shot action that should not need a describe first.

## Breaking

All shipped in 0.38.0. No deprecated aliases.

| Was | Now |
| --- | --- |
| `Connection.get_job` → `describe_job` | `Connection.open_job` returns
a populated `Job`, or raises |
| `Connection.job_history` → `query_job_events` | `job.events(...)` |
| `Connection.job` | `Connection.open_job` |
| Python events → `List[pa.RecordBatch]` | `pa.Table` |
| `JobDescription.spec_json` / `.result_json` | internal; use `job.spec`
/ `job.result` |

Node's `Job` is now a TypeScript class wrapping the native handle, so it
returns an Arrow table and parsed values like Python does. New
`Error::JobNotFound` / `JobNotFoundError`; the three job exceptions are
now in the Python API reference.

python/python/tests/test_remote_db.py

@@ -2467,7 +2467,7 @@ def test_remote_blob_byte_apis_not_supported_on_old_server():
 
 
 def test_remote_connection_jobs_surface():
-    from lancedb.exceptions import JobFailedError
+    from lancedb.exceptions import JobFailedError, JobNotFoundError
 
     schema = pa.schema([("state", pa.string())])
     batch = pa.record_batch([pa.array(["created", "done"])], schema=schema)
@@ -2475,6 +2475,7 @@ def test_remote_connection_jobs_surface():
     with pa.ipc.new_stream(sink, schema) as writer:
         writer.write_batch(batch)
     events_body = sink.getvalue().to_pybytes()
+    query_events_payloads = []
 
     def handler(request):
         content_len = int(request.headers.get("Content-Length", 0))
@@ -2512,6 +2513,22 @@ def test_remote_connection_jobs_surface():
             request.end_headers()
             request.wfile.write(json.dumps(rsp).encode())
         elif request.path == "/v1/jobs/describe":
+            if payload["job_id"] == "job-2":
+                request.send_response(200)
+                request.send_header("Content-Type", "application/json")
+                request.end_headers()
+                request.wfile.write(
+                    json.dumps(
+                        dict(
+                            job_id="job-2",
+                            job_type="refresh_column",
+                            job_state="DONE",
+                            creation_ms=2000,
+                            result=dict(rows_assigned=1000000, rows_failed=0),
+                        )
+                    ).encode()
+                )
+                return
             if payload["job_id"] != "job-1":
                 request.send_response(404)
                 request.end_headers()
@@ -2543,7 +2560,7 @@ def test_remote_connection_jobs_surface():
             request.end_headers()
             request.wfile.write(b'{"job_id": "job-1"}')
         elif request.path == "/v1/jobs/query_events":
-            assert payload["job_id"] == "job-1"
+            query_events_payloads.append(payload)
             request.send_response(200)
             request.send_header("Content-Type", "application/vnd.apache.arrow.stream")
             request.end_headers()
@@ -2559,24 +2576,109 @@ def test_remote_connection_jobs_surface():
         assert jobs[0].table == "t1"
         assert jobs[1].state == "finished"
 
-        description = db.get_job("job-1")
-        assert description.job_type == "create_index"
-        assert description.state == "failed"
-        assert json.loads(description.spec_json) == {"column": "vec"}
-        assert description.failure.message == "worker died"
-        assert description.failure.retryable is True
-        assert db.get_job("missing") is None
-
         assert db.cancel_job("job-1") is True
         assert db.cancel_job("missing") is False
 
-        batches = db.job_history("job-1")
-        assert len(batches) == 1
-        assert batches[0].num_rows == 2
-        assert batches[0].column("state").to_pylist() == ["created", "done"]
+        # Opening a job hands back a populated handle; a missing one fails.
+        with pytest.raises(JobNotFoundError, match="missing"):
+            db.open_job("missing")
+        finished = db.open_job("job-2")
+        assert finished.state == "finished"
+        assert finished.result == {"rows_assigned": 1000000, "rows_failed": 0}
 
-        job = db.job("job-1")
+        job = db.open_job("job-1")
         assert job.id == "job-1"
+        # Opening already populated the handle.
+        assert job.state == "failed"
+        assert job.spec == {"column": "vec"}
+        assert job.failure.message == "worker died"
         assert job.status() == "failed"
         with pytest.raises(JobFailedError, match="worker died"):
             job.wait(timeout=timedelta(seconds=5))
+
+
+def test_remote_job_handle_reports_its_own_detail():
+    schema = pa.schema([("state", pa.string())])
+    batch = pa.record_batch([pa.array(["claim_complete"])], schema=schema)
+    sink = pa.BufferOutputStream()
+    with pa.ipc.new_stream(sink, schema) as writer:
+        writer.write_batch(batch)
+    events_body = sink.getvalue().to_pybytes()
+    event_payloads = []
+
+    def handler(request):
+        content_len = int(request.headers.get("Content-Length", 0))
+        body = request.rfile.read(content_len) if content_len > 0 else b""
+        payload = json.loads(body) if body else {}
+        if request.path == "/v1/jobs/describe":
+            request.send_response(200)
+            request.send_header("Content-Type", "application/json")
+            request.end_headers()
+            request.wfile.write(
+                json.dumps(
+                    dict(
+                        job_id="job-1",
+                        job_type="refresh_column",
+                        job_state="DONE",
+                        creation_ms=2000,
+                        spec=dict(column="vec"),
+                        result=dict(rows_assigned=1000000),
+                    )
+                ).encode()
+            )
+        elif request.path == "/v1/jobs/query_events":
+            event_payloads.append(payload)
+            request.send_response(200)
+            request.send_header("Content-Type", "application/vnd.apache.arrow.stream")
+            request.end_headers()
+            request.wfile.write(events_body)
+        else:
+            request.send_response(404)
+            request.end_headers()
+
+    with mock_lancedb_connection(handler) as db:
+        job = db.open_job("job-1")
+
+        # Opening populates the handle in the same round trip.
+        assert job.state == "finished"
+        job.refresh()
+        assert job.job_type == "refresh_column"
+        assert job.creation_ms == 2000
+        assert job.spec == {"column": "vec"}
+        assert job.result == {"rows_assigned": 1000000}
+        assert job.failure is None
+        # The JSON payloads stay reachable, but as internal APIs.
+        assert json.loads(job._spec_json) == {"column": "vec"}
+        assert json.loads(job._result_json) == {"rows_assigned": 1000000}
+
+        # print() shows everything the handle knows and nothing it does not.
+        # print() lays every known field out on its own line, with the JSON
+        # payloads indented rather than crammed onto one line.
+        assert repr(job) == "\n".join(
+            [
+                "Job(",
+                "    id='job-1',",
+                "    state='finished',",
+                "    job_type='refresh_column',",
+                "    creation_ms=2000,",
+                "    spec={",
+                '        "column": "vec"',
+                "    },",
+                "    result={",
+                '        "rows_assigned": 1000000',
+                "    },",
+                ")",
+            ]
+        )
+        # Nothing it does not know shows up.
+        assert "failure" not in repr(job)
+
+        events = job.events(filter="state = 'claim_complete'", limit=500)
+        assert isinstance(events, pa.Table)
+        assert events.column("state").to_pylist() == ["claim_complete"]
+        # The handle supplies job_id; the caller only narrows the query.
+        assert event_payloads[-1] == {
+            "job_id": "job-1",
+            "limit": 500,
+            "filter": "state = 'claim_complete'",
+        }