The studio writes these attributes through `HF_AUDIO_FX_ATTR` and
`HF_AUDIO_AUTOMATION_ATTR` but reads them out of `dataAttributes`, which is
keyed without the `data-` prefix — so the read side carried its own
`"fx-chain"` and `"automation"` literals in four places. The two spellings had
no link, so a rename could only half-land: the writes would move and the panel
would go on reading an attribute nothing writes any more.
Both keys are now derived from their attribute (`HF_AUDIO_FX_DATA_KEY`,
`HF_AUDIO_AUTOMATION_DATA_KEY`) and the four read sites use them.
Falsified two ways. Repointing the derived key breaks 24 existing panel and
summary tests, which is what proves the reads actually go through it. And the
new one-line pairing assertion in each module fails the moment the derivation
is replaced by a literal again — which is the regression it exists for, since
a hardcoded key that happens to be right today passes every other test in the
suite.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
