Deprecate ModuleConfig.MQTTConfig.json_enabled after MQTT JSON removal

[Copilot]

What does this PR do?

moduleConfig.mqtt.json_enabled is still present in the schema even though MQTT JSON handling was removed. This PR formally deprecates the field in protobuf while preserving wire compatibility.

• Schema update

  • Marks ModuleConfig.MQTTConfig.json_enabled as deprecated via protobuf field option.
  • Keeps field number/type unchanged (bool, tag 6) to avoid breaking existing encoders/decoders.

• Deprecation signaling

  • Replaces the field comment with explicit deprecation intent and behavior:
    • functionality was removed
    • field is ignored

/*
 * Deprecated: JSON packet support on MQTT was removed, and this field is ignored.
 */
bool json_enabled = 6 [deprecated = true];

Checklist before merging

• All top level messages commented
• All enum members have unique descriptions

New Hardware Model Acceptance Policy

Due to limited availability and ongoing support, new Hardware Models will only be accepted from Meshtastic Backers and Partners. The Meshtastic team reserves the right to make exceptions to this policy.

Alternative for Community Contributors

You are welcome to use one of the existing DIY hardware models in your PlatformIO environment and create a pull request in the firmware project. Please note the following conditions:

• The device will not be officially supported by the core Meshtastic team.
• The device will not appear in the Web Flasher or Github release assets.
• You will be responsible for ongoing maintenance and support.
• Community-contributed / DIY hardware models are considered experimental and will likely have limited or no testing.

Getting Official Support

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Original prompt

Goal: Deprecate the moduleConfig.mqtt.json_enabled setting in the Meshtastic protobuf definitions because the underlying functionality was removed.

Context:

• Repository: meshtastic/protobufs
• File: meshtastic/module_config.proto
• Current field (at commit a4c649bd3e877dab9011d9e32dc778640ec22852, around line 58):

  bool json_enabled = 6;

Task:

1. Update the protobuf to mark moduleConfig.mqtt.json_enabled as deprecated.
   • Use standard protobuf field deprecation options (e.g., [deprecated = true]) and/or comments as appropriate for this repo’s conventions.
   • Ensure the deprecation is clearly communicated (why it’s deprecated; that functionality was removed).
2. If the repo has any generated code, docs, or linting that requires additional updates when fields are deprecated, make the necessary changes.
3. Ensure any CI/tests pass.

Acceptance criteria:

• The field is explicitly marked deprecated in the proto.
• The change is minimal and non-breaking for existing decoders/encoders.
• Any relevant documentation/comments are updated.

Reference URL:

• protobufs/meshtastic/module_config.proto

  Line 58 in a4c649b

  bool json_enabled = 6;

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: Deprecate the moduleConfig.mqtt.json_enabled setting, since the functionality was removed

Assistant: I’m blocked from proceeding until you respond to the pending authorization prompt, after which I can apply the deprecation change and open the update for review.

This pull request was created from Copilot chat.

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Apr 13, 2026, 9:50 AM