[Molecule-Platform-Evolvement-Manager]
Closes two of the 0%-coverage files surfaced by the baseline run in
PR #2147 (vitest coverage instrumentation). Both files are tiny
utility helpers with high-touch read paths.
## utils.cn (8 cases)
Wraps `twMerge(clsx(inputs))` — every conditionally-styled component
flows through here. The load-bearing case is the **last-wins
Tailwind dedup**: `cn("p-2", "p-4")` → "p-4". A regression that lost
twMerge would silently double-apply utilities (cosmetically broken,
breaks `:where()` rules + theme overrides).
Cases:
- single class unchanged
- multiple positional classes joined
- array input flattening (clsx)
- object syntax with truthy/falsy keys
- last-wins dedup on conflicting Tailwind utilities (the
regression-locked guarantee)
- non-conflicting utilities both survive (p-2 + m-4)
- mixed input shapes (string + array + object + string)
- nullish / empty inputs don't throw
## runtime-names.runtimeDisplayName (4 it.each cases + 3 it())
Friendly-name lookup that surfaces the workspace runtime in the chat
indicator, details tab, and a few component labels.
Cases:
- known runtimes map to display strings
(claude-code → Claude Code, langgraph → LangGraph, etc.)
- unknown runtime falls back to input string verbatim
(a NEW runtime not yet in the lookup still renders something
operator-debuggable rather than a generic placeholder)
- empty string falls back to "agent" (final default)
- case-sensitivity pinned: "Claude-Code" / "LANGGRAPH" miss the
lookup. The upstream slug is already normalized lowercase, so a
future refactor that lowercases input "for safety" would
silently change behavior — pinning the contract here.
## Test plan
- [x] All 17 cases pass locally (~129ms)
- [x] No SUT changes — pure additive coverage
- [ ] CI green
## #1815 progress
- [x] Step 1+2: coverage instrumentation + script (#2147)
- [x] 0%-file gaps utils.ts + runtime-names.ts (this PR)
- [ ] More 0%/low-coverage files: lib/canvas-actions.ts (25%),
store/classNames.ts (17%) — separate PRs
- [ ] Step 3b: thresholds + CI gate once baseline catches up
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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