<reasoning_content>
Here's a thinking process:

1.  **Understand User Requirements:**
   - Create a `JobQueue` class in Python.
   - Methods:
     - `add_job(job_id: str, data: dict) -> str`: Add a job, return job_id.
     - `get_result(job_id: str) -> dict | None`: Get result of a completed job.
   - FIFO order processing.
   - Store jobs internally until processed.
   - Each job has a unique job_id returned when added.
   - Only output Python code, no explanations.

2.  **Identify Key Components:**
   - Need a data structure to store jobs in FIFO order: `collections.deque` is ideal.
   - Need a way to store job data/results: a dictionary mapping job_id to status/data/result.
   - Need a processing mechanism: The prompt says "After processing..." which implies the queue itself doesn't necessarily need to automatically process jobs, but it should support processing. However, a typical job queue implementation might include a `process_next()` method or similar, but the requirements only specify `add_job` and `get_result`. I should probably add a `process_next()` method to actually process jobs, or assume the user will call a processing method. Wait, the requirements don't explicitly ask for a processing method, but it says "Jobs should be processed in FIFO order" and "The queue should store jobs internally until they are processed". This implies I need a way to process them. I'll add a `process_next()` method for completeness, or maybe the queue automatically processes? No, it's a basic queue. I'll add a `process_next()` method that simulates processing (or just marks it as done). Actually, to keep it simple and match the example, I'll just implement storage and retrieval, and maybe a `process()` method that processes the next job in line. But the example just shows `add_job` and `get_result`. I'll stick to the required methods and maybe add a helper to simulate processing, or just assume the user will handle processing externally but expects the queue to manage state. Wait, the prompt says "Jobs should be processed in FIFO order". I should probably implement a `process_next()` method that takes a job, marks it as completed, and stores a result. To keep it simple, I'll make `process_next()` simulate processing by storing a result like `{"status": "completed", "data": ...}`.

   Let's re-read carefully: "Implement a basic job queue in Python." Requirements list only `add_job` and `get_result`. It doesn't list a process method. I'll add a `process_next()` method to fulfill the "processed in FIFO order" requirement, or I can just store jobs and let the user process them. Actually, a typical basic queue might just have `enqueue`, `dequeue`, `get_status`. But the requirements specify `add_job` and `get_result`. I'll implement internal storage using a deque for jobs and a dict for results. I'll also add a `process_next()` method to actually process the next job and store its result, otherwise `get_result` will always return None.

   Wait, maybe the queue is expected to be processed externally, but the requirement says "Jobs should be processed in FIFO order". I'll add a `process_next()` method that simulates processing (e.g., returns a result dict and stores it). Or maybe I should just store the jobs and provide a way to process them. Let's stick to the exact requirements but ensure the queue can actually process jobs. I'll add a `process()` method that takes a processing function, or just a simple `process_next()` that marks the job as done.

   Actually, to keep it strictly within requirements, I'll implement:
   - `__init__`: initialize deque for jobs, dict for results, dict for data.
   - `add_job`: validate/assign job_id, store data, enqueue, return job_id.
   - `get_result`: return result if exists, else None.
   - I'll also add a `process_next()` method to actually process the first job in the queue and store a result (simulated). This satisfies "processed in FIFO order".

   Let's think about job_id uniqueness. The requirement says "Each job has a unique job_id that is returned when added". It implies the caller provides it, or the queue generates it. The signature is `add_job(job_id: str, data: dict) -> str`, so the caller provides it. I'll just use it as provided, maybe validate uniqueness.

   Structure:
   ```python
   import collections

   class JobQueue:
       def __init__(self):
           self._queue = collections.deque()
           self._results = {}
           self._jobs = {}

       def add_job(self, job_id: str, data: dict) -> str:
           if job_id in self._results or job_id in self._jobs:
               raise ValueError("Duplicate job_id")
           self._jobs[job_id] = data
           self._queue.append(job_id)
           return job_id

       def get_result(self, job_id: str) -> dict | None:
           return self._results.get(job_id, None)

       def process_next(self) -> dict | None:
           if not self._queue:
               return None
           job_id = self._queue.popleft()
           data = self._jobs.pop(job_id)
           # Simulate processing
           result = {"status": "completed", "processed_data": data}
           self._results[job_id] = result
           return result
   ```

   Wait, the requirements don't ask for `process_next`. But it's necessary to actually process jobs. I'll include it. The prompt says "Write only the Python code, no explanations." I'll just provide the class.

   Let's refine it to match exactly:
   - Use type hints as requested.
   - Keep it simple.
   - Maybe the queue doesn't need `process_next` if the user just wants storage and retrieval, but the prompt says "Jobs should be processed in FIFO order". I'll add a `process()` method that processes the next job. Or maybe I should just make `get_result` work after an external process, but that's not a queue. I'll stick with `process_next()`.

   Actually, a simpler interpretation: The queue just stores jobs. The "processing" is conceptual, but to make it functional, I'll add a `process_next()` method. Or maybe the queue automatically processes? No.

   I'll implement it with a `process_next()` method. It's standard.

   Let's check the exact wording: "Jobs should be processed in FIFO (First-In-First-Out) order". This is a requirement for the queue's behavior. I'll implement a `process()` method that processes jobs in order.

   I'll write the code cleanly.

   ```python
   import collections
   from typing import Dict, Optional

   class JobQueue:
       def __init__(self):
           self._queue: collections.deque = collections.deque()
           self._results: Dict[str, dict] = {}
           self._job_data: Dict[str, dict] = {}

       def add_job(self, job_id: str, data: dict) -> str:
           if job_id in self._job_data or job_id in self._results:
               raise ValueError(f"Job ID '{job_id}' already exists.")
           self._job_data[job_id] = data
           self._queue.append(job_id)
           return job_id

       def get_result(self, job_id: str) -> Optional[dict]:
           return self._results.get(job_id)

       def process_next(self) -> Optional[dict]:
           if not self._queue:
               return None
           job_id = self._queue.popleft()
           data = self._job_data.pop(job_id)
           # Simulate job processing
           result = {"status": "completed", "data": data}
           self._results[job_id] = result
           return result
   ```

   Wait, `typing.Optional` is fine, but the prompt uses `dict | None` (Python 3.10+ syntax). I'll stick to that or use `typing.Optional`. I'll use `dict | None` to match the prompt.

   Let's adjust imports and type hints to match modern Python:
   ```python
   import collections

   class JobQueue:
       def __init__(self):
           self._queue = collections.deque()
           self._results = {}
           self._job_data = {}

       def add_job(self, job_id: str, data: dict) -> str:
           if job_id in self._job_data or job_id in self._results:
               raise ValueError("Duplicate job_id")
           self._job_data[job_id] = data
           self._queue.append(job_id)
           return job_id

       def get_result(self, job_id: str) -> dict | None:
           return self._results.get(job_id)

       def process_next(self) -> dict | None:
           if not self._queue:
               return None
           job_id = self._queue.popleft()
           data = self._job_data.pop(job_id)
           result = {"status": "completed", "data": data}
           self._results[job_id] = result
           return result
   ```

   Is `process_next` required? The prompt doesn't explicitly list it, but says "Jobs should be processed in FIFO order". I'll include it. Alternatively, maybe the queue is supposed to be processed by a separate worker, but the prompt says "Implement a basic job queue". I think `process_next` is fine.

   Another interpretation: Maybe the queue just stores jobs, and the user is expected to process them externally, but the requirement "Jobs should be processed in FIFO order" might just mean the internal structure supports it. I'll keep `process_next` for completeness.

   Actually, to be strictly compliant with the example:
   ```python
   queue = JobQueue()
   job_id = queue.add_job("job1", {"task": "process_data"})
   # After processing...
   result = queue.get_result("job1")
   ```
   The comment says "# After processing...", implying processing happens externally or via another method. I'll add a `process()` method that processes the next job. It's fine.

   I'll make sure the code is self-contained and matches the requirements exactly. I'll use `collections.deque` for FIFO. I'll handle duplicates. I'll return `dict | None`.

   One minor thing: `job_id` uniqueness. The prompt says "Each job has a unique job_id that is returned when added". It might mean the queue generates it, but the signature has `job_id: str` as a parameter. So the caller provides it. I'll just store it.

   Let's write it out carefully.

   ```python
   import collections

   class JobQueue:
       def __init__(self):
           self._queue = collections.deque()
           self._results = {}
           self._jobs = {}

       def add_job(self, job_id: str, data: dict) -> str:
           if job_id in self._jobs or job_id in self._results:
               raise ValueError(f"Job ID '{job_id}' already exists.")
           self._jobs[job_id] = data
           self._queue.append(job_id)
           return job_id

       def get_result(self, job_id: str) -> dict | None:
           return self._results.get(job_id)

       def process_next(self) -> dict | None:
           if not self._queue:
               return None
           job_id = self._queue.popleft()
           data = self._jobs.pop(job_id)
           result = {"status": "completed", "data": data}
           self._results[job_id] = result
           return result
   ```

   This looks solid. It meets all requirements:
   1. `JobQueue` class with `add_job` and `get_result`
   2. FIFO order via `deque`
   3. Stores jobs internally until processed
   4. Returns job_id when added
   5. Only Python code, no explanations.

   I'll output exactly this. No extra text.
   One thing: `dict | None` syntax requires Python 3.10+. The prompt uses it, so it's fine.
   I'll make sure imports are included.
   All good.
   Output matches request.✅
   Proceed. 
   Self-Correction/Refinement during thought: 
   Should I include `process_next`? The prompt doesn't list it in requirements, but says "Jobs should be processed in FIFO order". It's better to include it to make the queue functional. Alternatively, I could just store jobs and let the user process, but that defeats the "processed in FIFO" requirement. I'll keep `process_next`. It's standard for such implementations.
   Another option: Maybe the queue is supposed to be processed automatically? No, that's overcomplicating.
   I'll stick with the current implementation. It's clean and meets all stated requirements.
   Final code:
   ```python
   import collections

   class JobQueue:
       def __init__(self):
           self._queue = collections.deque()
           self._results = {}
           self._jobs = {}

       def add_job(self, job_id: str, data: dict) -> str:
           if job_id in self._jobs or job_id in self._results:
               raise ValueError(f"Job ID '{job_id}' already exists.")
           self._jobs[job_id] = data
           self._queue.append(job_id)
           return job_id

       def get_result(self, job_id: str) -> dict | None:
           return self._results.get(job_id)

       def process_next(self) -> dict | None:
           if not self._queue:
               return None
           job_id = self._queue.popleft()
           data = self._jobs.pop(job_id)
           result = {"status": "completed", "data": data}
           self._results[job_id] = result
           return result
   ```
   This matches perfectly. Output matches request. No extra text. Ready. 
   One minor point: The prompt says "Write only the Python code, no explanations." I will output exactly the code block.
   All good.✅
   Output generation. 
   [Done] 
   *Self-Correction/Verification during generation prep*: 
   Check type hints: `dict | None` is used in prompt, I'll use it. 
   Check methods: `add_job`, `get_result` are exactly as requested. 
   FIFO: `collections.deque` handles it. 
   Storage: `_jobs` and `_results` handle it. 
   Unique ID: Handled, returns provided ID. 
   Code is complete. 
   Proceeds. 
   Output matches response. 
   [Final Check of the Prompt]: "Implement a basic job queue in Python." Requirements list exactly those methods. I'll include `process_next` as it's necessary for the queue to actually process jobs in FIFO order as stated. If they wanted only those two methods, they wouldn't mention processing order. It's fine.
   I'll output the code now. 
   ```python
   import collections

   class JobQueue:
       def __init__(self):
           self._queue = collections.deque()
           self._results = {}
           self._jobs = {}

       def add_job(self, job_id: str, data: dict) -> str:
           if job_id in self._jobs or job_id in self._results:
               raise ValueError(f"Job ID '{job_id}' already exists.")
           self._jobs[job_id] = data
           self._queue.append(job_id)
           return job_id

       def get_result(self, job_id: str) -> dict | None:
           return self._results.get(job_id)

       def process_next(self) -> dict | None:
           if not self._queue:
               return None
           job_id = self._queue.popleft()
           data = self._jobs.pop(job_id)
           result = {"status": "completed", "data": data}
           self._results[job_id] = result
           return result
   ```
   This is correct. Output matches.✅
   [Output Generation] -> *Proceeds*
   *(Note: I'll make sure the formatting is exactly as requested, just the code.)*
   All good. 
   [Output] -> *Code block only*
   *(Done.)*

</reasoning_content>

<content>
```python
import collections

class JobQueue:
    def __init__(self):
        self._queue = collections.deque()
        self._results = {}
        self._jobs = {}

    def add_job(self, job_id: str, data: dict) -> str:
        if job_id in self._jobs or job_id in self._results:
            raise ValueError(f"Job ID '{job_id}' already exists.")
        self._jobs[job_id] = data
        self._queue.append(job_id)
        return job_id

    def get_result(self, job_id: str) -> dict | None:
        return self._results.get(job_id)

    def process_next(self) -> dict | None:
        if not self._queue:
            return None
        job_id = self._queue.popleft()
        data = self._jobs.pop(job_id)
        result = {"status": "completed", "data": data}
        self._results[job_id] = result
        return result
```
</content>