fix(runtime): an unset or zero radius projects square corners

[SunkenInTime]

What

A painted box with no rounded-* utility was getting Native SDK's theme radius (6px at the smallest), because Weaver projected an unset radius as null and Native reads null as "theme default". rounded-[0px] hit the same > 0 test and was treated as unset too. Result: every small painted box has ~2px scalloped corners that no class can remove. Two Opus agents in the cadence experiment saw it on gapless progress segments; one redesigned its bar into a tick meter because of it.

Fix is one comparison: pass the retained radius through when it is >= 0. The tree's default is 0, so "no utility" now means square, as the contract's CSS model implies. Contract table gains the row.

Receipts

• Shipped examples are pixel-identical. Same widget sources, same fixtures, same clock, two runtime binaries from the same commit differing only in this line:

  Example	Pixels changed
  clock	0 / 42,240
  pomodoro	0 / 103,200
  weather	0 / 67,840
  system	0 / 66,640
  now-playing	0 / 52,800

  Every example specifies its radii; nothing relied on the theme default.

• Probe. 20 gapless 8px grow segments in a track. Per-column accent height on master: 468888888888863468888888888863… (each seam loses rows). With this change: 8888888888888888…. Same result for rounded-[0px] segments, for no radius class, and for fixed w-[14px] segments.

• Runtime test painted boxes without a rounded utility project square corners, not the theme radius. zig build test: 89 passed, 1 skipped.

Not in this PR

The other two open items from the experiment (a supported route for data-driven widths, and npx --no-install weaver outside the repo tree) are real decisions; evidence and options are written up in the experiment folder for Dara.

🤖 Generated with Claude Code

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[greptile-apps]

Greptile Summary

Painted boxes now preserve a zero radius when lowered to the Native SDK. Boxes with no rounding utility and boxes using rounded-[0px] receive square corners instead of inheriting the Native theme radius.

The portable runtime test suite passed with 89 tests passing and 2 skipped. Focused coverage confirms that both the retained default and an explicitly authored zero radius reach the Native widget style as an explicit 0.

Confidence Score: 5/5

Safe to merge: the changed rendering behavior is covered by passing runtime tests and direct projection assertions.

The retained default, zero-value normalization, Native optional-radius projection, and painted-box lowering path were checked. The portable Zig runtime suite and focused zero-radius regression both completed successfully.

Files Needing Attention: No follow-up changes are needed. Native-host rendering could not be exercised on Linux, but the runtime’s Native widget projection is directly asserted by the portable test coverage.

T-Rex Logs

What T-Rex did

• Validated that a retained node defaults radius to 0 and that Native projection forwards all non-negative radii as an optional value, and ran the portable Zig runtime suite with 89 tests passed and 2 skipped.
• Confirmed that the authored radius property is retained as zero and only negative radius values become the -1 unset sentinel, with Native receiving 0 as an explicit optional float and negatives lowered to null; compared the portable runtime results before and after the change and ran the focused radius projection regression.
• Documented the default retention and normalization in code paths and noted the provider socket deadline warning but a successful runtime with exit code 0.
• Summarized the retention/normalization, projection, and Native type declaration checks, along with the regression assertion that zero remains an explicit value in the built state.

_{Ran code and verified through T-Rex}

_{Reviews (2): Last reviewed commit: "Merge remote-tracking branch 'origin/mas..." | Re-trigger Greptile}