V115 Stayed Valuable Because It Was Preserved as a Known-Good Artifact

An old build can be more useful than a new branch when a regression removes the reference point.

The first engineering constraint behind V115 Stayed Valuable Because It Was Preserved as a Known-Good Artifact was concrete: LOUP preserved LOUP_V115_QUIET_AB_V1_APP_ONLY_0x20000.bin after it eliminated the major downlink stall and stayed stable in long calls.

That artifact became a control sample for later audio work. If a new build crackled, lagged or lost echo control, flashing V115 answered whether the board and PBX could still reproduce the earlier behaviour. Preservation also prevented source changes from rewriting history.

I kept the experiment narrow by changing one variable, capturing the observable result, and comparing it with a preserved working build before moving on. Evidence marker: v115-quiet-ab.

A firmware team needs immutable reference binaries, not only branches that can keep moving. In practice that keeps the next LOUP change measurable because the baseline remains available for comparison.

Project evidence

LOUP engineering marker: v115-quiet-ab. This note records the design or debugging lesson without publishing device credentials, private keys, customer data or manufacturing secrets.