Summary

This PR fixes the compression gauge on multi-slice sessions by resolving TX compression meters against the active TX slice instead of using last-match-wins global meter IDs.

The implementation now tracks COMPPEAK, AFTEREQ, and SC_MIC by TX waveform source when the radio provides explicit per-slice source indices, and by manifest slice context for repeated TX- num=0 blocks seen on 8000-series captures. RadioModel keeps MeterModel updated with the active TX slice so runtime TX reassignment selects the correct meter pair without reconnecting.

Investigation Notes

Issue #2040 matches our FLEX-6600 findings. The 6600 manifest repeats TX waveform blocks per slice, with observed SC_MIC / COMPPEAK pairs such as 22/23, 44/45, 66/67, and 88/89. Those numeric IDs are session-specific manifest slots, not API contracts. The old scalar indexes bound to the highest-numbered slice, so any other active TX slice could publish VITA meter values that were silently ignored.

For 6000-series radios without AFTEREQ, the derived gauge uses active-slice SC_MIC and COMPPEAK:

compression_lift_db = max(0, COMPPEAK - SC_MIC)
display_db = -clamp(compression_lift_db, 0, 25)

For 8000-series radios with AFTEREQ, the derived gauge uses active-slice AFTEREQ and COMPPEAK:

compression_lift_db = max(0, COMPPEAK - AFTEREQ)
display_db = -clamp(compression_lift_db, 0, 25)

The 8400M validation logs showed slice 0 using AFTEREQ 24 + COMPPEAK 25 and slice 1 using AFTEREQ 47 + COMPPEAK 48, with compression activity on both slices after TX reassignment.

Changes

• Replace scalar compression meter indexes with per-source and per-slice maps in MeterModel.
• Add active TX slice tracking from RadioModel into MeterModel.
• Clear stale compression state when the active TX slice changes or compression meter definitions are removed.
• Add throttled meter diagnostics showing selected reference meter, COMPPEAK, active slice, source index, freshness, lift, display value, and availability.
• Add unit tests for 6000-series explicit source mapping, 8000-series explicit source mapping, 8000-series repeated TX- num=0 mapping, sparse slice IDs, removal handling, freshness gating, and no-fallback behavior.
• Update meter documentation with current formulas, FPS notes, and multi-slice resolution rules.

Validation

• Rebasing branch onto latest origin/main at c215b4c completed cleanly.
• cmake --build build -j 10
• ./build/meter_model_test
• git diff --check
• Manual 8400M log review confirmed both slice 0 and slice 1 resolve active-slice compression pairs and show live compression values.

👨🏼‍💻 Generated with OpenAI Codex (GPT-5.5 Pro 4/23) and tested by @jensenpat