Q:

Solvilocks and the 17 chars

Once upon a time, a little user named Solvilocks
tramped into the woods and happened on a house
with three puzzles cooling on the windowsill
and nobody home.
The first puzzle was much too hard. &hairsp “Ow!”
The second puzzle simply seemed too easy. &hairsp Sneer.
This puzzle might turn out just right.
Your name to begin said the puzzle.
             
Little Solvilocks, typed little Solvilocks, and thought:
                                            &hairsp (Too easy too?)
 17 chars too many          ?
                                                         &hairsp  (Really?)
 16 chars too many          really?!
 15 chars too many          ?
 14 chars too many          this
 13 chars too many          is
 12 chars too many          silly
 11 chars too many          ?
 10 chars too many
or 9 chars too many           wha?
 8 chars too many           ?
 7 chars too many           ?
 6 chars too many
or Just right                 &hairsp
                                                        just right?
                                           &hairsp (I hope, I hope, I hope.)
 5 chars too many           just?!
 4 chars too many           !
 3 chars too many           -???
                                           &hairsp (Is this what it wants?)
 2 chars too many
or 1 char too many       why you...
           
                                         ??
        
               [  = blank ]
           
                                         ???
        
               [  = blank ]
 0 chars remaining
or 1 char remaining      ?????
 No chars remaining         ??????????
 2 chars remaining          -
 3 chars remaining          must
 4 chars remaining          stop
 5 chars remaining          typing
 6 chars remaining          compulsively
 7 chars remaining          rrrrrrrr
 8 chars remaining          ohhhhh
                                      &hairsp (Hmmmmm;) &hairsp (mmmmmm.)
 9 chars remaining          
                                                                    (Whew!)
              [  = empty entry ]
  
What would the puzzle say next?
 
(And why did it say everything else?)

All relevant information is only in what the puzzle said.
Everything else includes just one weak hint
and a red herring.

A:

It appears to me that

 The messages are self-referential in that they describe the difference between the number of characters in the message itself and the line number (starting from 0). I can't explain the blank entries: maybe the setter didn't find a solution for those or it would make the puzzle too obvious?

So, for instance,

 "17 chars too many" is on line 0 and has 17 characters, so 17 too many.

 For the lines marked with an or, the puzzle found more than one possibility. Take line 10: it's either "6 chars too many", which has 16 chars and therefore 6 too many, or "Just right", which has 10 characters, exactly what it should be.

The first thing to catch my eye were

 the lines with an "or" in them. If the answer changes depending on what the answer itself is, then surely something self-referential must be going on.

 Since all of the lines talk about character counts, that is the natural suspicion, and one can easily notice that the "or" points are the points in which the character count changes (either because of two digits -> one digit or singular -> plural).

As for the blanks,

 I'm guessing this happens because there is no way to make a correct answer of the format "[number] chars too many", "Just right", or "[number] chars remaining" for those lines.

 I do not like this because the rules as to what the puzzle might say don't seem so stringent at a first glance: it uses "no" instead of "0" in one of the lines, and the hint given in the community wiki uses "characters left" (if changing the wording is indeed illegal, that would be an evil red herring).

For the next line,

 If we assume the answer can only be in the format "[number] chars remaining", then we can't represent 27 characters that way, as "9 chars remaining" is 26 and "10 chars remaining" is 28. So that line would have to be a blank.

Summary table from puzzle’s poser:

 
    Target cutoff                          Target length
                \                         ---------------
                 \17 chars too many              0
                 1\6 chars too many              1
                 15\ chars too many              2
                 14 \chars too many              3
                 13 c\hars too many              4
                 12 ch\ars too many              5
                 11 cha\rs too many              6
            or/  10 char|s too many              7 \
              \  9 chars| too many               7 /
                 8 chars \too many               8
                 7 chars t\oo many               9
            or/  6 chars to|o many              10 \
              \  Just right|                    10 /
                 5 chars too\ many              11
                 4 chars too \many              12
                 3 chars too m\any              13
            or/  2 chars too ma|ny              14 \
              \  1 char too man|y               14 /
              x                 \               15 x
              x                  \              16 x
            or/  0 chars remaining|             17 \
              \  1 char remaining |             17 /
                 No chars remaining\            18
                 2 chars remaining  \           19
                 3 chars remaining   \          20
                 4 chars remaining    \         21
                 5 chars remaining     \        22
                 6 chars remaining      \       23
                 7 chars remaining       \      24
                 8 chars remaining        \     25
                 9 chars remaining         \    26
              x                             \   27 x
                 10 chars remaining          \  28    

A:

(Wikified worksheet – feel free to correct or add.)

What the puzzle “said”
can be grouped like this,
with ors on the same lines.

                                                                  mostly
   consecutive         consecutive                              consecutive
     stretch             stretch             oddballs             stretch
 -----------------   ----------------   ------------------   -----------------
                                        Your name to begin
 17 chars too many
 16 chars too many
 15 chars too many
 14 chars too many
 13 chars too many
 12 chars too many
 11 chars too many
 10 chars too many   9 chars too many
                     8 chars too many
                     7 chars too many
                     6 chars too many   Just right
                     5 chars too many
                     4 chars too many
                     3 chars too many
                     2 chars too many   1 char too many
                                        [blank]
                                        [blank]
                                        1 char remaining     0 chars remaining
                                        No chars remaining
                                                             2 chars remaining
                                                             3 chars remaining
                                                             4 chars remaining
                                                             5 chars remaining
                                                             6 chars remaining
                                                             7 chars remaining
                                                             8 chars remaining
                                                             9 chars remaining

From manshu:

I found a hint on OP’s chat profile.
In about section, it says 181 chars remaining:

 $\small\color{black}{\textsf{( From poser, a non-chat-profile equivalent if typed in a comment:}}$
 581 characters left
 $\small\color{black}{\textsf{)}}$

