dev-five-git · owjs3901 · Sep 12, 2026 · Sep 12, 2026
diff --git a/docs/integer-line-advance-verification.md b/docs/integer-line-advance-verification.md
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+# Integer pixel line advances: verified, visual gate rejected
+
+Measured on 2026-09-12 against base `442fc90699bb`. Absolute pixel emission
+reproduces the supplied Figma block heights, but fails the required
+no-regression bar at both wider landing widths. The experimental Rust change
+and its tests were removed; this report is the deliverable. No threshold,
+plugin golden, manifest checksum, fidelity classification, provenance entry,
+or source map was changed.
+
+## Binary identity and method
+
+Both builds used this worktree's own binary, rebuilt between measurements:
+
+```text
+C:/Users/owjs3/orca/workspaces/devup-mcp/W12-integer-advance/target/debug/devup-mcp.exe
+```
+
+Both reported `devup-mcp 0.4.5 (442fc90699bb-dirty)`. The baseline's dirty
+state contained only the newly written regression tests, with production
+code unchanged. SHA-256 distinguishes the actual executables:
+
+| Build | SHA-256 |
+| --- | --- |
+| Baseline | `38FBFAF5348131D509211AE8C57372FDF1128AB26EF93B8043B2968EF877CA45` |
+| Absolute pixel experiment | `88CB77AA3DDFFAC93FC42097B8EFF56D18E9D161EAB8396A03934973995116B8` |
+
+Each acquisition ran in the **main checkout** at
+`C:/Users/owjs3/Desktop/projects/devup-mcp/harness/render`, with
+`DEVUP_MCP_BIN` set to the path above, using `python scripts/acquire.py landing`.
+The existing call bank, dependencies, Chromium, and release visual comparator
+were used in place. There was no copied call bank or shared Cargo target.
+Comparison used channel tolerance 24.
+
+For the first two renders a temporary copy of `scripts/render.mjs` added
+read-only DOM measurements before its existing screenshot step; the render
+and comparison logic was unchanged. It selected the distinctive heading,
+subtitle, and benchmark text, recorded computed font size and line height,
+and read `getBoundingClientRect()`. Parent containers were excluded from the
+table using the element's matching text and computed font size. The temporary
+script was deleted before the test gate. Generated JSON measurement reports
+were retained in the main harness's ignored `out/` directory as
+`integer-baseline.json` and `integer-pixels.json`.
+
+## Independent mechanism verification
+
+Fresh snapshot acquisition reports `lineHeight.value = 129.99999523162842`
+with `unit = PERCENT` for these nodes. The candidate calculates
+`round(fontSize * percent / 100.0)` and emits the result with `px`; it does
+**not** round the ratio before multiplying or divide the rounded advance
+back by font size. Actual browser measurements reproduce all seven supplied
+rows before the change and match all seven design heights afterward:
+
+| Node | Font | Lines | Design height | Baseline DOM height | Pixel DOM height | Pixel computed line height |
+| --- | ---: | ---: | ---: | ---: | ---: | ---: |
+| `833:3646`, mobile heading | 38 | 5 | 245 | 246.953125 | 245 | 49px |
+| `833:3647`, mobile subtitle | 18 | 3 | 69 | 70.171875 | 69 | 23px |
+| `833:3664`, mobile benchmarks | 28 | 1 | 36 | 36.390625 | 36 | 36px |
+| `833:3328`, tablet heading | 52 | 4 | 272 | 270.375 | 272 | 68px |
+| `833:3329`, tablet subtitle | 24 | 2 | 62 | 62.375 | 62 | 31px |
+| `833:3346`, tablet benchmarks | 36 | 1 | 47 | 46.796875 | 47 | 47px |
+| `832:2980`, desktop heading | 52 | 4 | 272 | 270.375 | 272 | 68px |
+
+The baseline's computed advances were 49.4, 23.4, 36.4, 67.6, 31.2,
+46.8, and 67.6px respectively. The measurements validate the supplied rule
+for these captures, including its font-size-dependent sign reversal.
+
+## Tests first, then the actual emitter experiment
+
+Before changing either emitter, a temporary integration test exercised
+`generate_devup_json` with the captured percentage at font sizes 38, 18, 52,
+and 36, expecting `49px`, `23px`, `68px`, and `47px`. A second test exercised
+`generate_component` on an unstyled 52px text node, expecting
+`lineHeight="68px"`.
+
+```text
+cargo test --locked -p devup-mcp-devup-ui --test integer_line_advance -j 2
+
+RED: 0 passed; 2 failed
+percentage_style_rounds_the_advance_at_each_font_size:
+  font size 38; left: Number(1.3); right: "49px"
+inline_percentage_text_rounds_the_advance:
+  emitted <Text boxSize="100%" fontSize="52px" lineHeight="1.3">
+```
+
+Only afterward, `typography_value()`'s PERCENT branch was changed to read
+the style's numeric `fontSize` and emit
+`format_px((size * percent / 100.0).round())`. `line_height()` took a numeric
+font-size argument and did the same for both node and rich-text segment
+callers. AUTO and pixel-valued branches were unchanged. Repeating the same
+test command gave **2 passed, 0 failed**. The binary was then rebuilt and
+all three screens freshly acquired from that experimental binary.
+
+This was a bounded experiment, not a completed general token implementation.
+The landing themes use their own font sizes: mobile h1 is 38px and the two
+wider h1 values are 52px. Computed browser sizes and advances above prove that
+the larger headings did not accidentally receive the mobile 49px advance.
+
+A fixed pixel token is valid for its associated font size only. A node that
+overrides that size needs a newly computed pixel advance from its resolved
+size and percentage; responsive token slots likewise need their own advances.
+Codegen currently receives a style-ID-to-token-name map, not the style
+metrics needed to compare overrides. A complete implementation would need
+that metadata or explicit resolved node/segment overrides. A missing numeric
+font size or a font-size variable that can change by mode cannot safely use
+one precomputed pixel advance. The temporary candidate did not solve those
+cases and is not retained as production code. They do not explain this
+experiment's regression: the measured landing headings have known numeric
+sizes and exact correct pixel advances.
+
+## All-width visual result
+
+| Screen | Width | Baseline binary | Pixel-emission binary | Required maximum | Decision |
+| --- | ---: | ---: | ---: | ---: | --- |
+| `landing-833-3640` | 360 | 11.41% | 9.64% | strictly below 11.41% | Local gain |
+| `landing-833-3322` | 992 | 3.10% | 3.71% | 3.10% | Reject |
+| `landing-832-2975` | 1920 | 1.84% | 2.31% | 1.84% | Reject |
+
+The candidate render exited 1 for both wider regressions. Page heights were
+2955 / 2964 / 3084px at baseline and 2955 / 2966 / 3086px with pixel emission.
+No threshold was tightened for the rejected mobile-only improvement.
+
+The local correction succeeded; the aggregate screenshot constraint resisted
+it because local line advance is not the only remaining geometry or glyph
+difference. Concrete evidence:
+
+| Node | Design Y | Baseline Y | Pixel Y |
+| --- | ---: | ---: | ---: |
+| Mobile subtitle | 359 | 360.953125 | 359 |
+| Mobile benchmarks | 888 | 893.125 | 890 |
+| Tablet subtitle | 546 | 544.375 | 546 |
+| Tablet benchmarks | 940 | 940.75 | 942 |
+| Desktop subtitle | 496 | 494.375 | 496 |
+| Desktop benchmarks | 900 | 900.75 | 902 |
+
+The corrected subtitle positions match exactly, but each benchmark section
+still begins two pixels below its design position. At wider widths the
+baseline's short text partly offset that downstream displacement; fixing the
+text exposes more of it. The source of that separate displacement is not
+established here, and no width-specific or unrelated layout correction was
+added to conceal it.
+
+Direct PNG measurement also separates advance from glyph placement. Selecting
+primary-blue pixels (`abs(R-90)<25`, `abs(G-68)<25`, `B>230`, more than two
+pixels per row) within the heading rectangles produced these inclusive bands:
+
+| Heading | Figma | Baseline | Pixel emission |
+| --- | --- | --- | --- |
+| Mobile, x=16 y=90 w=328 h=245 | 101–127 / 150–176 / 199–225 | 101–127 / 150–176 / 200–226 | 101–127 / 150–176 / 199–225 |
+| Desktop, x=280 y=200 w=551 h=272 | 216–251 / 284–319 / 352–387 | 214–250 / 282–318 / 349–385 | 215–251 / 283–319 / 351–387 |
+
+The desktop pixel candidate has exact 68px band advances, yet its glyph bands
+start one pixel above Figma's and are a different height. Absolute advances
+therefore solve the demonstrated accumulation defect without solving all
+font rasterization/placement or downstream layout errors. The wider
+regression cannot be attributed to re-emitting a ratio or sharing the wrong
+font-size advance: neither occurred in this run.
+
+## Corpus and final verification
+
+Changed plugin goldens: **none**. Changed manifest checksums: **none**.
+The rejected experiment was removed before the final gate, so all 268 pinned
+goldens remain the original reviewed contract. The consistency test was not
+weakened. All forbidden files remain untouched.
+
+Final gate commands used
+`CARGO_PROFILE_DEV_DEBUG=0`, `CARGO_PROFILE_TEST_DEBUG=0`,
+`CARGO_INCREMENTAL=0`, and `CARGO_BUILD_JOBS=2`, without `CARGO_TARGET_DIR`.
+
+| Gate | Result |
+| --- | --- |
+| `cargo fmt --all -- --check` | Pass |
+| `cargo clippy --locked --workspace --all-targets --all-features -j 2 -- -D warnings` | Pass, zero warnings |
+| `cargo test --workspace -j 2 --no-fail-fast` | 1049 passed, 0 failed, 2 ignored |
+| `cargo insta test --workspace --all-features --check` | Pass; no snapshots to review |
+| `cargo test --locked -p devup-mcp --test stdio_smoke` | 2 passed, 0 failed |
+
+Test linking emitted the existing localized MSVC library-creation
+`linker_messages` warnings; the clippy command itself emitted zero warnings.
+The report was staged before the gate, and no temporary untracked files were
+introduced during it, so the build-identity check passed.
+
+Finally, fresh acquisition from the restored worktree binary followed by the
+unchanged `node scripts/render.mjs` passed the existing thresholds at
+**11.41% / 3.10% / 1.84%**. The restored executable's SHA-256, recorded before
+that acquisition, was
+`8479CA649C9B8DCDC45F1E5AEB11A2A148851654434BB8C671240827A9D18159`.
+The generated harness inputs are thus back on the baseline generator. No
+experimental emitter, failing experimental test, or temporary render script
+is retained in the commit. The line-advance defect remains open because its
+isolated correction fails the mandatory no-regression gate.