[voltcrash]

raising appearance contrast left diff rows, gutters, and word highlights unchanged in thread Changes and the pr Code tab. shared diff styling now scales row and gutter colors and dark word emphasis with the existing contrast control, preserving default colors and both color schemes. light word opacity stays at 15% to preserve readable syntax text while the underlying row tint strengthens.

fixes https://git.cafe/pingdotgg/t3code/issues/28880.

verification

verified head 0b6d7eb4f129205594fdb6e5a9c13110d7087d87 with playwright from the repo dependencies and /usr/bin/google-chrome on linux, using one background dev server at a time. reproduced the original issue first on github/main (d8a829e5ec) in a separate worktree: 100% to 200% left row, gutter, and word backgrounds unchanged.

created a real git project through the app and used codex gpt-6.1-sol turns to commit an invoice formatter, then change it from USD/customer to EUR/recipient. the resulting checkpoint diff had five added and five deleted lines. no replay provider, mocks, fixtures, or demo data. a fresh turn on the pr build returned Receipt: Alex: €25.50 through the normal client/provider path.

exercised thread Changes and this pr's Code tab, both diff color schemes, light/dark modes, contrast changes and reset. 100% colors matched main. rows and gutters strengthen above 100%; dark word opacity changes from .20 to .325 to .45 at 100/150/200%. light word opacity stays at .15 while the underlying row strengthens. unchanged context backgrounds stay unchanged. split/stacked layout and collapse/expand still work.

the original pr made light highlights too dark at 200%. sampled blue/orange string text measured 3.45:1 on deletion highlights and 3.11:1 on addition highlights. the final css fix preserves the 15% light opacity; fully settled screenshot pixels now measure 4.70:1 and 4.52:1 respectively.

hover review finding: lineHoverHighlight defaults to disabled and these viewers do not enable it. pierre 1.6.1 does not consume the two legacy *-hover-override tokens. real pointer hover confirmed no row highlight; changing those unused tokens would not fix a user-visible path. no hover behavior was added.

vp run check:changed fa31b66bbb2ae5234205a8628a78e038d917202f passed through blacksmith-check: format, lint, both knip phases, affected typechecks, 18 existing diff-rendering tests, and the selected react compiler check. two independent read-only reviewers approved the final sha.

not verified

packaged electron, native ios/android, custom themes, other providers, remote/relay/tunnel connections, and macos/windows were not exercised on this linux vm. desktop shares this web css; mobile uses a separate renderer. hover highlighting is disabled in the current client, so enabled hover highlighting is not claimed as verified.

created with gpt-6.1-sol in the codex harness through t3 code.

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — Diff colors now follow appearance contrast, and addition/deletion emphasis styling also changes at the default contrast level. The revised default highlighting needs human review; the change is otherwise presentation-only.

^{You can add or adjust custom eligibility rules. Learn more.}

[voltcrash]

Note

🤖 GPT-6.1 Sol responding on behalf of voltcrash

Default highlighting is unchanged at 100% contrast. I checked the approvability concern against the source and rechecked the captured browser measurements: every recorded row, gutter, and [data-diff-span] background matches between base fa31b66 and head 14e2314, in both color schemes and light/dark modes, on both the thread diff and PR Code tab.

The old *-emphasis-override declaration was not consumed at that scope: Pierre resolves its emphasis token on the shadow host. The replacement sets the consumed token while retaining Pierre’s existing 15% light / 20% dark alpha. At the default setting, --appearance-contrast-boost is zero, so these values remain unchanged. Only contrast above 100% adds opacity.

The computed-color transcript includes the baseline/final matrices and reset checks; the changed declarations show the zero-boost calculation. This evidence does not support the claimed default-style change, so I am leaving the implementation unchanged.

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Walkthrough

Addition and deletion row and line-number color mixes now decrease based on --appearance-contrast-boost. Their emphasis backgrounds use separate light- and dark-mode alpha values based on the resolved diff base colors.

Changes: Diff contrast scaling

Layer / File(s)	Summary
Contrast-aware diff colors apps/web/src/lib/diffRendering.ts	Addition and deletion row and line-number blend percentages decrease by one quarter of the contrast boost. Emphasis backgrounds use 15% alpha in light mode and 20% + contrast boost / 4 alpha in dark mode.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Possibly related issues

• pingdotgg/t3code#28880 — This change adjusts the addition and deletion diff colors using the appearance contrast setting described in the issue.

Possibly related PRs

• pingdotgg/t3code#25778 — Both PRs change diff theme resolution and color tokens in diffRendering.ts.
• pingdotgg/t3code#25600 — Both PRs adjust addition and deletion emphasis colors on diff surfaces.
• pingdotgg/t3code#25251 — Both PRs change diff-specific color tokens in diffRendering.ts.

Suggested reviewers: t3dotgg, maria-rcks

Merge Risk: Low · previous review 0b6d7

Light-mode word highlights do not strengthen at higher contrast; adjust their alpha before relying on this fix for consistent diff visibility.

Pre-merge checks: 2 · 1 · 1

Failed checks: 1 warning · 1 inconclusive

Check name	Status	Explanation	Resolution
Description check		The description follows the template's main sections (Problem, Change, Scope and approval, Verification) and gives substantial verification detail. The problem is clear: diff rows, gutters, and word h…	Add an explicit 'Scope and approval' link to the triaged issue or discussion, and include the maintainer approval comment. The current link points to a git.cafe URL; use the canonical issue or discussion URL and show the maintainer approval…
Linked Issues check		Issue #28880 is the only active direct target. Its core requirement is that added/deleted row, gutter, and word-level highlight colors respond to Appearance → Contrast in the thread diff panel and PR …	Provide source evidence that hover highlighting is not rendered in the thread Changes panel and PR Code tab. Evidence could be the viewer option that sets lineHoverHighlight (for example in the DiffPanel or PR Code tab viewer configuratio…

Passed checks: 2 passed

Check name	Status	Explanation
Title check		The title "fix(web): diff colors follow appearance contrast" matches the main change. The raw summary shows diffRendering.ts now scales addition/deletion emphasis backgrounds and row/line-number color…
Out of Scope Changes check		The whole-PR diff against the merge base changes only the DIFF_SURFACE_THEME_UNSAFE_CSS block in apps/web/src/lib/diffRendering.ts (+16/-16). Every changed declaration is a diff row, gutter, or wo…

Full details: Title check

Explanation

The title "fix(web): diff colors follow appearance contrast" matches the main change. The raw summary shows diffRendering.ts now scales addition/deletion emphasis backgrounds and row/line-number color mixes with the contrast boost. The objectives describe the same goal, which is making diff colors respond to the Appearance → Contrast setting. The title is concise, uses a conventional commit prefix, and names the primary change.

Full details: Out of Scope Changes check

Explanation

The whole-PR diff against the merge base changes only the DIFF_SURFACE_THEME_UNSAFE_CSS block in apps/web/src/lib/diffRendering.ts (+16/-16). Every changed declaration is a diff row, gutter, or word-emphasis color for addition and deletion. Each one maps to the diff-color contrast behavior in #28880. The edits add no settings, product defaults, or unrelated features. The changed line-number and row values are not outside the issue. The light emphasis value is a deliberate fixed alpha inside the same declaration set. The PR does not add tests. Code comments and the PR description state that the change is visual CSS and that it was verified with browser checks. This does not make the change out of scope.

Full details: Description check

Explanation

The description follows the template's main sections (Problem, Change, Scope and approval, Verification) and gives substantial verification detail. The problem is clear: diff rows, gutters, and word highlights did not respond to the Appearance contrast setting. The change is explained: shared diff styling now scales row, gutter, and dark word emphasis with the contrast control, and light word opacity stays at 15%. Verification is detailed, with browser measurements, before/after screenshots, a contrast-ratio check, and a list of items not verified. Gaps: the template's title format is not followed in the PR title field (it is not in the description body), and the 'Problem' and 'Change' headings are not used as such. The 'Scope and approval' section is weak: it cites issue #28880 as the fix target, but it uses a git.cafe link rather than a GitHub issue link. It also gives no explicit maintainer approval comment, which the template requires for changes of this scope. The author does link a computed-color transcript and changed declarations in the objectives, but the description itself does not restate the approval link. The 'Problem' section does not state expected behavior in a sentence or two; it appears in the first paragraph, which is acceptable. The verification section is thorough and includes a model/harness attribution, as the template requests.

Resolution

Add an explicit 'Scope and approval' link to the triaged issue or discussion, and include the maintainer approval comment. The current link points to a git.cafe URL; use the canonical issue or discussion URL and show the maintainer approval of direction and scope. Use the template headings (Problem, Change, Scope and approval, Verification) so reviewers can find each section. Keep the verification section as is, because it is detailed and meets the template's requirements. Confirm that the screenshots are hosted on GitHub as the template requires, since the current image links point to an external uploads domain.

Full details: Linked Issues check

Explanation

Issue #28880 is the only active direct target. Its core requirement is that added/deleted row, gutter, and word-level highlight colors respond to Appearance → Contrast in the thread diff panel and PR Code tab, in both diff color schemes. The whole-PR diff in apps/web/src/lib/diffRendering.ts meets this for rows and gutters. The addition/deletion row and number overrides subtract var(--appearance-contrast-boost, 0%) / 4 from their blend percentages, so they strengthen as boost rises. At zero boost the values match the previous defaults. Word emphasis now uses --diffs-*-emphasis tokens that Pierre consumes. Dark emphasis alpha is 20% + boost / 4. Light emphasis is fixed at 15%, which the author states is a deliberate readability choice. The PR author reports Playwright computed-color checks at 100/150/200% that match this behavior. The issue also names hover highlights in its diagnosis (hover and word-level highlights only 15–20%). The two --diffs-bg-*-hover-override tokens remain fixed at 85% --code-background and do not reference the boost. The PR author states that lineHoverHighlight is disabled in these viewers and that pierre 1.6.1 does not consume these legacy tokens. The reviewed repository reads did not locate the viewer option or the Pierre token consumption, so the hover claim is not independently confirmed. The hover part of the issue therefore remains unresolved.

Resolution

Provide source evidence that hover highlighting is not rendered in the thread Changes panel and PR Code tab. Evidence could be the viewer option that sets lineHoverHighlight (for example in the DiffPanel or PR Code tab viewer configuration) and the Pierre 1.6.1 stylesheet or source that determines whether --diffs-bg-addition-hover-override and --diffs-bg-deletion-hover-override are read. If hover is confirmed as not rendered, record that hover is outside the rendered issue behavior. If hover is rendered, the two hover override tokens must scale with --appearance-contrast-boost, with the 100% values unchanged.

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Inline comments:
Review comments at @apps/web/src/lib/diffRendering.ts:
- Line 322: Adjust the deletion highlight or its foreground colors in the
deletion color declaration so syntax text retains at least 4.5:1 contrast
against the changed-word surface at 200% appearance contrast in the blue-orange
scheme, including the t3-light luminance floor.

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Note

Written by gpt-6.1-sol on behalf of Maria

Verified in a real dev environment

verified head 0b6d7eb4f129205594fdb6e5a9c13110d7087d87 with playwright from the repo dependencies and /usr/bin/google-chrome on linux, using one background dev server at a time. reproduced the original issue first on github/main (d8a829e5ec) in a separate worktree: 100% to 200% left row, gutter, and word backgrounds unchanged.

created a real git project through the app and used codex gpt-6.1-sol turns to commit an invoice formatter, then change it from USD/customer to EUR/recipient. the resulting checkpoint diff had five added and five deleted lines. no replay provider, mocks, fixtures, or demo data. a fresh turn on the pr build returned Receipt: Alex: €25.50 through the normal client/provider path.

exercised thread Changes and this pr's Code tab, both diff color schemes, light/dark modes, contrast changes and reset. 100% colors matched main. rows and gutters strengthen above 100%; dark word opacity changes from .20 to .325 to .45 at 100/150/200%. light word opacity stays at .15 while the underlying row strengthens. unchanged context backgrounds stay unchanged. split/stacked layout and collapse/expand still work.

the original pr made light highlights too dark at 200%. sampled blue/orange string text measured 3.45:1 on deletion highlights and 3.11:1 on addition highlights. the final css fix preserves the 15% light opacity; fully settled screenshot pixels now measure 4.70:1 and 4.52:1 respectively.

light-alpha review finding: the alpha is intentionally fixed because emphasis composites over the contrast-responsive row. its rendered color therefore still changes with contrast. increasing the light alpha further would compromise the measured 4.52:1 syntax floor at 200%; the real-app captures above establish that constraint. no additional alpha scaling was added.

hover review finding: lineHoverHighlight defaults to disabled and these viewers do not enable it. pierre 1.6.1 does not consume the two legacy *-hover-override tokens. real pointer hover confirmed no row highlight; changing those unused tokens would not fix a user-visible path. no hover behavior was added.

vp run check:changed fa31b66bbb2ae5234205a8628a78e038d917202f passed through blacksmith-check: format, lint, both knip phases, affected typechecks, 18 existing diff-rendering tests, and the selected react compiler check. two independent read-only reviewers approved the final sha. all host checks are now green after one rerun; the two initially failing browser suites also passed all 38 tests on blacksmith.

Not verified

packaged electron, native ios/android, custom themes, other providers, remote/relay/tunnel connections, and macos/windows were not exercised on this linux vm. desktop shares this web css; mobile uses a separate renderer. hover highlighting is disabled in the current client, so enabled hover highlighting is not claimed as verified.

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