<reasoning_content>
*   Target: A basic job queue in Python.
    *   Class name: `JobQueue`.
    *   Method 1: `add_job(job_id: str, data: dict) -> str`. Returns `job_id`.
    *   Method 2: `get_result(job_id: str) -> dict | None`. Returns result or `None`.
    *   Order: FIFO (First-In-First-Out).
    *   Internal storage: Store jobs until processed.
    *   Uniqueness: Unique `job_id`.
    *   Constraint: Only Python code, no explanations.

    *   Need a way to store the queue of jobs (FIFO). A `collections.deque` is standard for this.
    *   Need a way to store the results of processed jobs. A dictionary `results` would work.
    *   Need a way to keep track of which jobs are pending vs done.
    *   The prompt implies that "processing" happens elsewhere or is implicit. However, for a functional implementation, I need a way to mark a job as "done" so `get_result` can return something. Since the prompt doesn't specify a `process_job` method but asks for `get_result`, I should probably provide a way to simulate completion or assume that `get_result` only returns values for jobs that have been "finished".
    *   Wait, the prompt says "Jobs should be processed in FIFO order". Usually, this implies a worker loop or a `process_next()` method. If I only have `add_job` and `get_result`, I need a way to transition a job from "queued" to "completed".
    *   Looking at the example usage: `job_id = queue.add_job(...)` then `result = queue.get_result(job_id)`.
    *   Actually, a pure "Queue" implementation usually involves a `process_next()` or a worker thread. But the prompt specifically asks for these two methods. To make `get_result` work, I'll need a way to simulate or store the result.
    *   Perhaps I should add a hidden/internal way to set the result, or assume `process_next` is implied?
    *   Re-reading: "Jobs should be processed in FIFO order". This means if I add A then B, A is finished first.
    *   Let's look at the structure:
        - `self.queue`: A deque of `job_id`s.
        - `self.jobs`: A dict mapping `job_id` to `data`.
        - `self.results`: A dict mapping `job_id` to `result`.
    *   How does a job get "processed"? The prompt doesn't provide a `process` method in the signature requirements.
    *   Let's add a `process_next` method internally or provide a way for the user to trigger it? No, the prompt says "Create a `JobQueue` class with the **following** methods" (listing only two).
    *   Maybe the `get_result` is supposed to return `None` until the queue is empty? No, that's not how job queues work.
    *   Wait, maybe I should implement a simple worker thread? No, that's overcomplicating.
    *   Let's look at the instructions again. "Jobs should be processed in FIFO order". This might imply that I should provide a way to process them.
    *   Actually, a very standard "Job Queue" interview question usually includes a `process_next` or similar.
    *   Let's try to satisfy the requirement by having a private/helper method to simulate processing, or just have a way to simulate the result.
    *   Actually, I'll just implement the two requested methods. To make `get_result` non-None, I'll assume that for the sake of the test, I can add a `complete_job` method or similar, but since only two are asked for, I'll assume the "processing" happens automatically or via a background thread.
    *   Actually, a simple way to interpret "processed in FIFO" is that `get_result` returns `None` until the items before it in the queue are "done".
    *   But there's no "done" trigger.
    *   Let's assume a simple dictionary storage for jobs and results. I'll include a `process_next` method just to make the logic work, but the prompt only asks for two. I'll stick to the two requested and maybe a simple `complete_job` for internal use or just a way to simulate the logic.
    *   Actually, looking at standard Python job queue implementations, usually there's a worker.
    *   Let's provide the two methods. To satisfy "processed in FIFO", I'll use a `collections.deque`. To make `get_result` return something, I'll assume a job is "completed" when it's popped from the queue.
    *   Let's refine:
        1. `self.queue` = `deque()` (stores job_ids).
        2. `self.job_data` = `{}` (stores input data).
        3. `self.results` = `{}` (stores result data).
        4. `add_job` -> appends to `queue`, adds to `job_data`.
        5. `get_result` -> if job_id is in `results`, return it.
        6. But how does it get into `results`?
        7. Maybe I'll add a `process_next` method even if not asked for, to make it functional? Or maybe I'll just implement the requested ones and leave the "processing" part as a logical flow.
    *   Wait, the prompt says "Write only the Python code".
    *   I will provide a `process_next` method anyway because otherwise the `get_result` method will always return `None` and the FIFO requirement is meaningless. I'll put it in as a standard method.
    *   Actually, I'll just stick to the requirements. If `get_result` returns `None` until something happens, that's fine. But how does it happen?
    *   Maybe the user expects me to handle the processing in a thread?
    *   Let's try this: `add_job` adds to queue. `get_result` checks if it's done. I'll add a `process_next` method to actually move jobs from queue to results.

    *   Correction: The prompt is specific. "Create a JobQueue class with the following methods". It doesn't forbid other methods, but usually, it implies those are the interface.
    *   Let's look at Requirement 2: "Jobs should be processed in FIFO order".
    *   If I implement a `process_next` method:
        ```python
        def process_next(self):
            if self.queue:
                jid = self.queue.popleft()
                self.results[jid] = {"status": "completed", "data": self.job_data[jid]}
        ```
    *   This fulfills FIFO.

    *   Actually, to keep it simple and strictly follow "Write only the Python code":
    *   I will implement exactly what is asked. To allow the example usage to work (where `get_result` is called after "processing"), I'll assume there's an internal mechanism or I'll just provide a `complete_job` helper.

    *   Let's rethink. If I only have `add_job` and `get_result`, how can "processing" happen?
    *   Maybe `get_result` itself triggers processing? No, that's not right.
    *   I'll provide a `process_next` method. It makes the most sense for a "Job Queue".

    *   Wait, looking at the prompt again: "The queue should store jobs internally until they are processed".
    *   I'll use a `deque` for the queue and a `dict` for results.

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

    class JobQueue:
        def __init__(self):
            self.queue = deque()
            self.results = {}
            self.job_data = {}

        def add_job(self, job_id: str, data: dict) -> str:
            self.queue.append(job_id)
            self.job_data[job_id] = data
            return job_id

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

        def process_next(self):
            if self.queue:
                job_id = self.queue.popleft()
                # Simulate processing
                self.results[job_id] = {"result": "success", "original_data": self.job_data[job_id]}
    ```

    *   Wait, if I include `process_next`, I am adding a method not explicitly asked for. But without it, the "processed in FIFO" requirement is impossible to demonstrate.
    *   Actually, I'll just provide the two asked methods. If the user wants to process them, they can assume a process happens. But wait, `get_result` needs a result.

    *   Let's try a different approach. Maybe `get_result` should check the queue? No.
    *   I will provide the two methods and a `process_next` method so the code is actually usable.

    *   Wait, the prompt says: "Write only the Python code, no explanations."
    *   I'll stick to the two requested methods and a small `process_next` to make the example work.

    Actually, looking at Requirement 3: "The queue should store jobs internally until they are processed". This implies there's a state change.

    Let's refine the `JobQueue` class:
    ```python
    from collections import deque
    from typing import Dict, Optional

    class JobQueue:
        def __init__(self):
            self.queue = deque()
            self.results = {}
            self.job_data = {}

        def add_job(self, job_id: str, data: dict) -> str:
            self.queue.append(job_id)
            self.job_data[job_id] = data
            return job_id

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

        def process_next(self):
            if self.queue:
                job_id = self.queue.popleft()
                # Logic to "process" the job
                self.results[job_id] = {"status": "completed", "data": self.job_data.get(job_id)}
    ```

    Wait, I'll check if `job_id` is unique. The prompt says "Each job has a unique job_id". I should probably check for that.

    Final Structure:
    ```python
    from collections import deque
    from typing import Dict, Optional

    class JobQueue:
        def __init__(self):
            self.queue: deque[str] = deque()
            self.job_data: Dict[str, dict] = {}
            self.results: 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("Job ID must be unique")
            self.queue.append(job_id)
            self.job_data[job_id] = data
            return job_id

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

        def process_next(self) -> None:
            if self.queue:
                job_id = self.queue.popleft()
                # Simulated processing logic
                self.results[job_id] = {"status": "completed", "data": self.job_data.get(job_id)}
    ```

    One detail: "Jobs should be processed in FIFO order". This is handled by `popleft()` on a `deque`.

    I'll omit `process_next` from the final code unless it's necessary for the logic? The user asked for two methods. I'll provide exactly those two and maybe a `process_jobs` helper if I feel it's necessary, but strictly speaking, I should just provide what's asked. But if I don't provide a way to complete a job, `get_result` will always be `None`.

    Wait, I can make `get_result` check the queue? No, that's not right.
    I'll include `process_next` as a helper because it's essential for the "FIFO" requirement to be meaningful.

    Actually, I'll check the example usage:
    `job_id = queue.add_job("job1", {"task": "process_data"})`
    `# After processing...`
    `result = queue.get_result("job1")`
    The "After processing..." implies that processing happens outside the `JobQueue` class or via another method.

    If it's outside, how does the `JobQueue` know it's done?
    The `JobQueue` class needs a way to receive the result.
    Maybe a `complete_job(job_id, result)` method?
    The requirements don't mention `complete_job`.

    Let's look at the requirements again.
    1. `add_job`
    2. `get_result`
    3. FIFO order.
    4. Store jobs until processed.
    5. Unique `job_id`.

    If I can't add `complete_job`, and `get_result` is the only way to get data out, and there's no way to tell the class a job is done... then the class must have a way to process them.
    I will include a `process_next` method to satisfy the FIFO requirement.

    Actually, I'll stick to the two requested methods. To make it functional, I'll assume `get_result` returns `None` until the item is popped from the queue by some logic. I'll add a `process_next` method anyway, it's the only way to make sense of "FIFO".

    Wait, I'll look at the `deque` usage.
    If I only have `add_job` and `get_result`, I'll just implement them. If the user wants to "process", they might expect a `process_next` method.

    Let's consider a different interpretation: `get_result` processes the queue? No.
    I will provide a `process_next` method. It's standard for a Job Queue.

    Wait, I'll just implement the two requested ones and a `complete_job` or `process_next`. I'll go with `process_next`.

    Actually, let's look at Requirement 3: "The queue should store jobs internally until they are processed".
    This means my `self.queue` should hold the jobs.

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

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

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

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

        def process_next(self):
            if self._queue:
                job_id = self._queue.popleft()
                # Simulate some work
                self._results[job_id] = {"status": "completed", "data": self._jobs.get(job_id)}
    ```

    Is there a way to do this without `process_next`?
    Maybe `get_result` checks if the job is at the front of the queue? No, that doesn't make sense.
    I'll include `process_next` but I won't mention it in the requirements block if I were writing an essay, but since I'm only writing code, I'll just write it.

    Actually, to be safe, I will only provide the requested methods, but I'll add a `complete_job` method so it's actually usable. Or better, I'll just provide the two asked ones and a `process_next` method.

    Wait, I'll provide a `process_next` method because "processed in FIFO order" is a requirement. If I don't have a `process_next`, there is no "processing" happening in the class.

    Final check on requirements:
    1. `add_job(job_id: str, data: dict) -> str`
    2. `get_result(job_id: str) -> dict | None`
    3. FIFO order.
    4. Store jobs internally until processed.
    5. Unique `job_id`.

    One more thought: Maybe `get_result` is supposed to return the result *after* the queue is empty? No, that's not a job queue.

    I'll provide the requested two plus a `process_next` to make the "processed in FIFO" part possible.

    Actually, I'll just provide the two. If the user wants to process them, they'll have to figure out how. But that makes the code useless.
    I'll include `process_next`.

    Wait, I'll check if I can do it with just those two.
    If `add_job` puts it in a `deque`, and `get_result` just looks at a `results` dict.
    Then the "processing" must be external. If it's external, how does the `JobQueue` know it's done?
    It can't.
    Unless... there is a `complete_job` method.
    I'll add `complete_job(job_id, result)`.

    Wait, the prompt says "Create a JobQueue class with the **following** methods".
    This usually means *only* those methods or at least those methods are required.
    I will provide only those two and a `process_next` method just to make the logic functional.

    Actually, I'll use a dictionary to store jobs and a deque for the IDs.
    I will add `process_next` to ensure FIFO.
</reasoning_content>

<content>
```python
from collections import deque
from typing import Dict, Optional

class JobQueue:
    def __init__(self):
        # Stores job IDs in FIFO order
        self._queue: deque[str] = deque()
        # Stores input data for pending jobs
        self._jobs: Dict[str, dict] = {}
        # Stores results for completed jobs
        self._results: Dict[str, dict] = {}

    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._queue.append(job_id)
        self._jobs[job_id] = data
        return job_id

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

    def process_next(self) -> None:
        """
        Helper method to process the next job in the FIFO queue.
         This satisfies the requirement that jobs are processed in FIFO order.
        """
        if self._queue:
            job_id = self._queue.popleft()
            # Simulate processing logic
            data = self._jobs.pop(job_id, {})
            self._results[job_id] = {
                "status": "completed",
                "original_data": data,
                "result": "success"
            }
```
</content>