feat(mqtt): leveld parser

[qzhuyan]

Description

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Fixes #(issue)

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce.

• Test A
• Test B

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Performance Impact

• This change improves performance
• This change has no performance impact
• This change may have performance implications (please describe)

Security Considerations

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• This change has security implications (please describe)

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.87063% with 186 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.91%. Comparing base (722f1d9) to head (a3b9a69).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/mqtt_serde/parser/leveled.rs	89.26%	167 Missing ⚠️
src/mqtt_serde/parser/stream.rs	94.00%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #94      +/-   ##
==========================================
+ Coverage   74.78%   76.91%   +2.12%     
==========================================
  Files          63       66       +3     
  Lines       15062    17049    +1987     
==========================================
+ Hits        11264    13113    +1849     
- Misses       3798     3936     +138     

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[Copilot]

Pull request overview

Adds a “leveled” MQTT parsing mode to support parsing packets at different depths (type-only, raw body, headers-only, or full), enabling consumers to trade parsing cost for throughput.

Changes:

• Introduces parser::leveled with ParseLevel, ParsedPacket, and level-specific parse functions.
• Extends MqttParser with parse_level configuration and a new next_parsed() API.
• Adds ControlPacketType::from_first_byte() and MqttPacket::packet_type() helpers used by the leveled parser.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/mqtt_serde/parser/stream.rs	Adds parse-level configuration and next_parsed() to the streaming parser.
src/mqtt_serde/parser/mod.rs	Exposes the new leveled parser module.
src/mqtt_serde/parser/leveled.rs	Implements leveled parsing (L0–L3) plus unit tests.
src/mqtt_serde/mod.rs	Re-exports ParseLevel from the crate root.
src/mqtt_serde/control_packet.rs	Adds helpers to extract/control packet type information.
mqtt_grpc_duality/src/bin/r-proxy.rs	Removes stray whitespace in imports.

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[Copilot]

parse_headers_only() routes both MQTT v3.1 (3) and v3.1.1 (4) to parse_headers_only_v3, but the returned HeadersParsedPacket hard-codes mqtt_version: 4. This misreports the negotiated protocol version when parsing v3.1 packets. Consider passing the input mqtt_version through (or storing 3 vs 4 based on the caller) instead of always using 4.