diff --git a/.planning/PROJECT.md b/.planning/PROJECT.md
index 1f5405b..b171ee4 100644
--- a/.planning/PROJECT.md
+++ b/.planning/PROJECT.md
@@ -18,6 +18,8 @@ All 16 v1 requirements validated. Full pipeline working: capture -> classify ->
 
 **Phase 5 complete 2026-03-26:** Waveform types (sine, square, sawtooth, triangle) with bandlimited synthesis added. OscillatorBank decoupled from global config — NewBank now accepts injected config maps with dynamic gain scaling.
 
+**Phase 6 complete 2026-03-26:** TOML config system added. Users can override frequency and waveform per traffic class via `netsynth.toml` (auto-discovered or `--config` flag). Partial overrides, unknown-key validation, and fail-fast startup errors. New `config` package with BurntSushi/toml.
+
 ## Requirements
 
 ### Validated (v1.0)