---
phase: 09-frequency-design-and-group-architecture
plan: "02"
subsystem: config
tags: [frequency-design, auto-assign, collision-prevention, test-update]
dependency_graph:
  requires: []
  provides: [updated-autoAssignFreq-range, collision-free-auto-assign]
  affects: [config/config.go, config/config_test.go]
tech_stack:
  added: []
  patterns: [FNV-32a hash, deterministic frequency assignment]
key_files:
  created: []
  modified:
    - config/config.go
    - config/config_test.go
decisions:
  - "autoAssignFreq range moved to [2500, 4000] Hz with numSteps=31 (50 Hz steps) to guarantee 51 Hz gap above max built-in frequency of 2449 Hz"
  - "TestAutoFreqSkipsBuiltins updated to expect 150.0 for HTTPS (coordinated with Plan 01 rebalancing)"
metrics:
  duration: "~3 min"
  completed: "2026-03-27"
  tasks_completed: 2
  files_modified: 2
---

# Phase 9 Plan 2: Auto-Assign Frequency Range Update Summary

Update autoAssignFreq to use [2500, 4000] Hz with 31 steps of 50 Hz, ensuring no collision with any built-in frequency (max 2449 Hz after Phase 9 Plan 1 rebalancing).

## What Was Built

Updated the `autoAssignFreq` function constants and corresponding test assertions so user-defined traffic classes are always assigned frequencies in the [2500, 4000] Hz range, safely above all built-in protocol frequencies.

## Tasks Completed

| Task | Name | Commit | Files |
|------|------|--------|-------|
| 1 | Update autoAssignFreq constants and comment | 8ae1ddc | config/config.go |
| 2 | Update config_test.go auto-assign range assertion | dbcbeb3 | config/config_test.go |

## Changes Made

### Task 1: config/config.go

- Changed `baseHz` constant from `1200.0` to `2500.0`
- Changed `numSteps` from `uint32(24)` to `uint32(31)` (covers [2500, 4000] in 50 Hz steps: 2500 + 30*50 = 4000)
- Updated function comment from `[1200, 2350]` to `[2500, 4000]`
- `stepHz = 50.0` unchanged

### Task 2: config/config_test.go

- Updated `TestAutoFreqAssignment` comment from `[1200, 2350]` to `[2500, 4000]`
- Updated range bounds assertion from `< 1200.0 || > 2350.0` to `< 2500.0 || > 4000.0`
- Updated `TestAutoFreqSkipsBuiltins` HTTPS expected value from `175.0` to `150.0` (coordinated with Plan 01 HTTPS rebalancing)

## Verification Results

- `go build ./config/...` exits 0
- `TestAutoFreqAssignment` passes
- `TestAutoFreqDeterministic` passes
- `TestAutoFreqSkipsBuiltins` will pass once Plan 01 updates HTTPS BaseHz to 150.0

## Deviations from Plan

None - plan executed exactly as written.

## Known Stubs

None.

## Self-Check: PASSED

- config/config.go contains `baseHz   = 2500.0`: FOUND
- config/config.go contains `numSteps = uint32(31)`: FOUND
- config/config_test.go contains `cfg.BaseHz < 2500.0 || cfg.BaseHz > 4000.0`: FOUND
- Commits 8ae1ddc and dbcbeb3 exist in git log