feat(layout,render): converge inline pipeline — vertical writing modes (slice 2)

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Summary

Slice 2 of the render↔layout inline-pipeline convergence (#270 = slice 1). Extends the InlineFlow persist+consume convergence to vertical writing modes, dropping the !is_vertical gate.

Render's vertical legacy path (emit_styled_segments_vertical) is a single-column linear pass with no line-breaking → multi-line / multi-run vertical text renders wrong today (all lines collapse into one column). This slice fixes it by having render consume layout's per-line InlineFlow — a correctness fix, not just dedup.

Changes

Layout (elidex-layout-block)

• Drop !is_vertical from the InlineFlow persist gate.
• Apply the is_vertical projection swap when folding the IFC origin — the same rule static_positions / assign_inline_layout_boxes use: inline-axis → physical x (horizontal) or y (vertical), block-axis → y or x. Each stored scalar then holds the absolute physical coordinate for its axis (no vertical-rl block reversal — matching the box convention). FlowAlign's resolution was already inline-axis-agnostic, so vertical text-align needed only enabling.

Render (elidex-render)

• Unified emit_inline_flow branches horizontal vs vertical at the glyph emit (shared per-line/run loop); vertical derives the column center_x from block_start/block_size and the pen y from inline_start.
• Extracted shared emit_vertical_text_segment / vertical_text_orientation (mirrors the horizontal emit_text_segment sharing; the legacy driver now delegates to it).
• The converged dispatch reads only writing_mode + text_orientation (Copy) — no ComputedStyle clone on the hot path; a styleless parent → horizontal default (mirrors layout's get_style unwrap_or_default, so a persisted flow is still painted).
• Citation sweep: Writing-Modes cites normalized to Level 4; fixed the §4.1 (= Introduction to Baselines) → §3.1 (Introduction to Vertical Writing) content mismatch.

Tests

+6 layout (vertical-rl/lr persist, the axis-swap proof, multi-column, vertical + justify-still-gated) + 1 render (multi-column vertical consume — x-separation between columns + downward y-advance within a column). Removed the now-obsolete slice-1 gate_excludes_vertical_writing_mode.

Edge matrix (per the inline white-space density lesson)

Covered: vertical-rl/lr persist · axis-swap (block↔x / inline↔y) · multi-column (wrap) · text-align baked into inline_start · all other gates (justify/pseudo/atomic/relpos/bidi/text-transform/fragmentation) still excluded · multi-column render. The shared orientation (mixed/upright/sideways) + vertical-decoration logic is a byte-identical extraction from the verified legacy path (covered by extraction fidelity); forced-break columns use the same packer line-break mechanism as wrap.

Deferred (program-internal, plan §10, cap-neutral)

• vertical-rl block-axis reversal: columns paint left-to-right, matching the pre-existing static_positions/box convention (consistent with clientRects — not a new divergence). WritingModeContext::is_block_reversed() exists but is unwired across boxes + static-pos + InlineFlow; wiring it is a standalone WM-correctness project.
• per-segment vertical metrics (column width from font_size) · shared inline_logical_to_physical helper (unify the 3 projection copies) · bidi reorder in the converged vertical path → slice 4.

Cap-neutral (One-issue-one-way + conformance/correctness, no new web-platform feature).

Pre-push gate: cargo fmt + mise run ci (10634 tests) + /code-review + /simplify + /review + /elidex-review (0 CRIT / 0 IMP) all green.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR extends the layout↔render inline-pipeline convergence (InlineFlow persist+consume) to vertical writing modes, fixing previously incorrect rendering of wrapped/multi-line vertical text by having render consume layout’s per-line/per-run geometry.

Changes:

• Layout: removes the vertical-writing-mode persistence exclusion and applies an is_vertical-aware origin fold so persisted InlineFlow coordinates are absolute physical coordinates.
• Render: unifies InlineFlow consumption for horizontal/vertical (branching at glyph emission), extracts shared vertical segment emission/orientation helpers, and avoids cloning ComputedStyle on the converged hot path.
• Tests/docs: adds vertical persistence/axis-swap/multi-column coverage and a render consume test for multi-column vertical flow; updates Writing-Modes citations and InlineFlow coordinate documentation.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
crates/layout/elidex-layout-block/src/inline/tests/inline_flow.rs	Adds vertical-writing-mode persistence tests; removes the slice-1 vertical gate test.
crates/layout/elidex-layout-block/src/inline/pack.rs	Updates FlowAlign docs to be writing-mode/inline-axis agnostic.
crates/layout/elidex-layout-block/src/inline/mod.rs	Drops !is_vertical from the persistence gate; applies axis-swap when folding IFC-local to absolute physical coordinates.
crates/core/elidex-render/src/builder/tests/inline_flow.rs	Adds a vertical InlineFlow consume test for multi-column output.
crates/core/elidex-render/src/builder/inline.rs	Threads writing-mode/orientation into InlineFlow consume; adds vertical branch consumption and extracts shared vertical segment emission/orientation.
crates/core/elidex-ecs/src/components.rs	Documents InlineFlow coordinate semantics after writing-mode projection at persist (horizontal vs vertical).

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

crates/core/elidex-render/src/builder/inline.rs:419

• emit_inline_flow currently skips a run entirely when run.entity has no ComputedStyle. That contradicts the nearby intent comment about a styleless parent still being painted (layout persists with unwrap_or_default semantics), and can make persisted flows silently render nothing if style data is missing. Consider falling back to ComputedStyle::default() for missing styles (and keep the visibility check).

        for run in &line.runs {
            let Ok(style) = dom.world().get::<&ComputedStyle>(run.entity) else {
                continue;
            };
            // visibility: hidden text occupies space (laid out) but is not painted.
            if style.visibility != Visibility::Visible {
                continue;