fix(checker): preserve explicitly authored straight route intent - #397

Problem and value

Schema-valid route: "straight" relationships in architecture, data-flow, and lifecycle diagrams can render successfully but fail check, validate, and atomic deliver solely because the final artifact checker treats every diagonal as unintended. On base 6db72a9, the lifecycle reproduction renders M 307 157 L 493 307, then fails orthogonal_arrows.

Preserve explicit straight intent in a small renderer-generated SVG attribute. The checker accepts that attribute only on a semantic relationship with one actual direct segment. This recovers the supported authoring behavior without altering paths or broadly accepting unmarked diagonals. This is a recovered fuzz finding; the minimal redacted reproductions are in archify/test/authored-straight-routes.test.mjs.

Stability impact

• Contract repair across three renderers and the shared artifact checker. Automatic routes, workflow routing, explicit endpoint-side validation, opaque-node clearance, and other quality gates retain their existing behavior.
• Previously rendered unmarked HTML keeps the strict diagonal check; rerender the supported JSON to carry its authored intent into the artifact.
• Nonempty via overrides straight and cannot acquire the direct-route exception. Empty via remains compatible for architecture/lifecycle. Data-flow retains its existing orthogonal-via validation.
• Only actual two-point authored diagonals receive metadata; axis-aligned straight relationships and existing example bytes stay unchanged. The checker rejects stale markers on bent/curved paths and markers without semantic edge identity.
• The lifecycle design guidance now distinguishes the axis-aligned recommendation from the supported explicit straight option.
• No schema, dependencies, Viewer behavior, finite-SVG validation, default router, version, or release identity changes. This does not incorporate the separate fix(checker): scope finite_svg to numeric attributes (#372) #373 finite-SVG or fix(architecture): infer endpoint side from the dominant axis, not the bare dx sign #379 inferred-side changes.

Tests run

Base 6db72a9aea3d0f67a6a034e41f8a5491476a11c1; candidate 4f8e59416a4488b9dd7e95d642ad1486fd938619. Node 22.23.2 on macOS:

• New end-to-end regression file: 14 passed. Covers all three modes under standard/showcase through render → check → validate → deliver, exact path/point preservation, marker removal, auto routing, explicit-side rejection, via precedence, and invalid-marker controls.
• Existing render-output-checks, layout-rules, v1-compatibility, and gallery suites: 138 passed.
• Base reproduction: all three minimal inputs render successfully and fail only orthogonal_arrows; the candidate retains the same endpoint coordinates and SVG d.
• Golden checks passed, including both development and packaged examples. Gallery generation reproduced its 11 checked-in artifacts and 99 checks.
• Extracted ZIP outside the repo, without node_modules or installation: the same 14 end-to-end checks passed.
• Full npm test: 1359 total; 1311 passed, 1 failed, 47 skipped. The sole failure is the pre-existing checked-in MCO byte-reproducibility drift (its old HTML still uses network fonts). The same test fails on clean base 6db72a9; base and candidate regenerate the pinned MCO artifact to identical bytes (SHA-256 3c53dea72ae62c91cb367a0e835f0ebd4aa1e4aa8719747278593aea60177180, 823676 bytes). The unrelated MCO artifacts are unchanged. Chrome-gated/optional tests remain explicitly skipped; this is not a claim of a green complete local suite.
• Independent review found an empty-via gap, which was fixed; both new empty-via delivery cases passed independent replay. No remaining in-scope review blocker.

Visual evidence

Not applicable: the SVG geometry, styling, and Viewer code are unchanged. Fixed inputs preserve the exact paths/points, and existing example/Gallery output remains byte-identical. The visible difference is successful delivery of explicitly authored straight routes. Browser/perceptual acceptance is not claimed.

Generated artifacts

archify.zip regenerated with official Node 22.23.2 and reproduced byte-for-byte by a second build. Its 79-entry inventory is unchanged; only the seven affected renderer/checker/documentation entries differ from base. Examples, Gallery, guide/start pages, README showcase, and Viewer outputs need no regeneration because their authoritative generated output remains unchanged.

Final-head hosted CI passed on 4f8e594 across Node 18/20/22/24, browser/WebM, ZIP freshness, published-manifest and all three package-smoke platforms: CI run. This does not reclassify the documented pre-existing local MCO failure.