Need help interoperating between comint and CLI app's multi-line mode

[pareto optimal via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

Hello all, been stuck on this one for quite some hours :)

I'm trying to make an inferior comint based mode for memgpt.

In a terminal outside of emacs, when I use `memgpt run`, it has a special multi-line mode you can enter with `//`.

It looks like:

```
> Enter your message: //
> Enter your message:  (Finish with 'Alt+Enter' or 'Esc then Enter')
>
  - say hi
  - count to 10
  - say sayonara (I press Alt+enter)
💭 User wants to say hi, count to 10, and say sayonara. Handling the commands one by one.
🤖 Hello! How are you doing today? I'm all ears. Oh, and one, two, three...
```

The problem is in emacs if you just do something like this to run it with comint:

```
(progn
  (make-comint "memgpt" "memgpt" nil "run" "--strip-ui")
  (pop-to-buffer "*memgpt*"))
```

Then you go into multi-line mode, you'll get an error about `M-RET` not being bound. That's surmountable since I can bind `M-RET` to something.

```
(process-send-string "*memgpt*" "\e\r") ;; send escape codes for ESC enter to underlying process
```

The problem is that process-send-string sends at the beginning of the line.

I can prove that. Given comint buffer below and `|` denoting the cursor:

```
> Enter your message:  (Finish with 'Alt+Enter' or 'Esc then Enter')
  - say hi
  - count to 10
  - say sayonara|
```

Send:

```
(process-send-string "*memgpt*" "****")
```

and you get:

```
> Enter your message:  (Finish with 'Alt+Enter' or 'Esc then Enter')
****  - say hi
  - count to 10
  - say sayonara
```

So when I send `(process-send-string "*memgpt*" "\e\r")` I predictably get this result:

```
Empty input received. Try again!
> Enter your message:  (Finish with 'Alt+Enter' or 'Esc then Enter')
  - say hi
  - count to 10
  - say sayonara
```

Well a little confusing since it puts the response above your input string.

Then I went to the docs and found `comint-accumulate`. This is a not too horrible workaround and does work, but the output is a little noisy and strange if you don't know exactly whats happening:

```
> Enter your message:  (Finish with 'Alt+Enter' or 'Esc then Enter')
  - say hi
  - count to 10
  - say sayonara

>
    - say hi
      - count to 10
        - say sayonara
        
        
        > Enter your message:  (Finish with 'Alt+Enter' or 'Esc then Enter')
>
    - say hi
      - count to 10
        - say sayonara
        
        
        
💭 INSERT silly wrong LLM output
```

Any guidance or advice would really help so I can have a comint memgpt that isn't much more terrible to use than the normal version.

Thanks!