Fix overlapping comment highlights

[HamptonMakes]

Why

A new open comment nested inside an older resolved anchor was persisted but disappeared after reload because both threads shared the resolved anchor's invisible highlight.

What

• Give overlapping comment anchors independent nested highlight elements
• Keep open nested highlights interactive and route clicks to the innermost thread
• Cover the exact single-word heading selection, Enter submission, reload, and click flow

Risk Assessment

Low — limited to overlapping inline comment anchors; the existing comment UX and anchoring system suites pass.

Generated with Amp

[HamptonMakes]

what does this do?

[chatgpt-codex-connector]

💡 Codex Review

coplan/engine/app/javascript/controllers/coplan/text_selection_controller.js

Lines 842 to 844 in 074e4ea

	const mark = document.createElement("mark")
	mark.className = className
	range.surroundContents(mark)

Preserve click access for fully overlapping threads

When two threads anchor the exact same range, this unconditional nesting makes the later mark completely cover the earlier one; because openThreadPopover() now stops propagation, clicking the highlighted text can only open the inner thread, leaving the outer thread’s popover unreachable by mouse. This commonly occurs when multiple reviewers select the same phrase, so fully coincident anchors need a way to expose both threads rather than routing every click exclusively to the newest nested mark.

AGENTS.md reference: AGENTS.md:L138-L142

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