The Walking Dead: Season 9

Season overview

Role: Meticulous television and film archivist.
Task: Produce a JSON object for The Walking Dead Season 9.
Keys: overview (160-220 word summary), primer (array of exactly 4 concise bullet points).
Constraints: Use ONLY provided synopsis and sources. No invented facts. No markdown/asterisks/headings/bullets in the text (except the JSON array structure). Output valid JSON only.
Source Analysis:
TMDB Season Synopsis: Survivors are rebuilding civilization under Rick's leadership after defeating Negan and the Saviors. The group faces a new threat: walkers that have started whispering.
Source [1]: General info, Rick Grimes awakens from coma.
Source [2]: Created by Frank Darabont, stars Andrew Lincoln, Norman Reedus, Melissa McBride, Lauren Cohan. Rick Grimes leads survivors.
Source [3]: Rick Grimes finds family and survivors in a world of flesh-eating zombies.
Source [4]: Developed by Frank Darabont, based on comics by Robert Kirkman, Tony Moore, Charlie Adlard.
Source [5]: Season 1 info (not relevant for Season 9 narrative).
Overview:
Following the defeat of Negan and the Saviors, the survivors are engaged in the process of rebuilding civilization. This reconstruction effort takes place under the leadership of Rick Grimes. While the group works toward establishing a more stable society, they are confronted by a significant and unprecedented threat. The walkers in their environment have begun to exhibit new behavior, specifically starting to whisper. This development forces the group to face what is described as their biggest threat yet. The series, which is an American post-apocalyptic horror drama developed by Frank Darabont, continues to follow the struggle of these survivors in a world dominated by flesh-eating zombies. As they attempt to move past the conflict with the Saviors, the emergence of these whispering walkers presents a new challenge to the stability they are trying to achieve under Rick's guidance. (Word count check: ~145 words. Need to expand to 160-220 words using only provided info).
Expanding Overview (to meet 160-220 requirement):
Following the defeat of Negan and the Saviors, the survivors are now focused on rebuilding civilization. This reconstruction effort is being conducted under the leadership of Rick Grimes. As the group works to establish a new way of life, they are forced to face what is described as their biggest threat yet. The walkers surrounding the group have begun to exhibit a new and unsettling behavior, as they have started whispering. This development presents a major challenge to the survivors as they attempt to