Incorrect flagging of mass noun squirming

**What got flagged?**

Text: `Cobalt stirs in my front pocket, agitated by my spiking heartbeat. Zinc follows, both squirming as I nudge their heads back down.`

**Why is this incorrect?**
The word squirming was flagged as a mass noun, suggested to replace with both pieces of squirming, which is clearly wrong in this context.

**Example of correct usage:**
See the text in flagged section. Both is slightly ambiguous but that's the entire paragraph.

No implementation file or test is named. Start by reproducing the warning with the reported sentence and trace the mass-noun diagnostic for “squirming”; done means this usage is no longer flagged or given the incorrect “both pieces of squirming” suggestion, while other mass-noun cases remain covered.

Written by the indexing model from the issue text.