Upstream provenance and compatibility boundary

Dagro implements the default Dagre layout path used by D2. The version constants identify behavioral source revisions, not complete API coverage.

Pinned sources

Source	Revision	Test artifact
@dagrejs/dagre 3.1.1	c3ed0802cd98de74c21cff1f754689ebbb0f8dae	npm integrity sha512-zroZB1dFOFiGgv4Xcrn1DckB1o4aOikPqD2NDQPV0WM//CXGcS6xiD0rNkqHmw6FEg4tabt4nxPLwgCWT+Vb2A==; dist/dagre.cjs SHA-256 70b9a4367932dd436075d98892a7968d65cf66ae83263f995e0531823b59b671
@dagrejs/graphlib 4.0.5	d3a0cf36f55ebd75f28b6acf7a436a54e1b990dc	npm integrity sha512-7xrBTqIts3o+PMUZX97wSc+7TUbW+/rULzGNCTP6yooNVDXbzw4Wutg/H/xOutTB/c/k0YqOAavgPh4/Zk9PFA==; dist/graphlib.cjs SHA-256 271f39d50dbcf2f795808cb4f5b90fb42a096b5f84b4dd6bb672487b454011e7

The test-only package.json and lockfile pin those exact packages. CI pins Node 24.19.0 and uses npm ci --ignore-scripts; neither JavaScript package is a production dependency.

The compatibility oracle is rebuilt from the exact Dagre commit by testdata/differential/build-dagre-3.1.1-d2-compat.sh. The builder verifies upstream package-lock.json SHA-256 9f5e1e7a40667dcffc12e35ea5d4db96f346dadf943e97c1ecc2b4dc21afbb2d, applies the pinned source patch, runs the upstream build with esbuild 0.27.3, tsx 4.21.0, TypeScript 5.9.3, and Graphlib 4.0.5, and verifies patched dist/dagre.js SHA-256 9b91fccee8e70a74299cf47eaf8100c46a900fb1f334a11424ff3682c1019585. The generated test-only CommonJS oracle has SHA-256 8e34c25ed53dbccca2fa206780b0b46974b285c74e0cd7b34d0d1fafa5506cab; it is generated in CI and is not checked in or shipped.

Source map

Upstream source	Dagro implementation
lib/layout.ts, lib/coordinate-system.ts, lib/position/index.ts	layout.go, coordinate_system.go, position.go
lib/acyclic.ts, lib/greedy-fas.ts	acyclic.go, greedy_fas.go
lib/nesting-graph.ts, lib/normalize.ts, lib/parent-dummy-chains.ts, lib/add-border-segments.ts	nesting_graph.go, normalize.go, parent_dummy_chains.go, add_border_segments.go
lib/rank/*.ts	rank.go, rank_util.go, feasible_tree.go, network_simplex.go
lib/order/*.ts	order.go and order_*.go
lib/position/bk.ts	position_bk.go
lib/util.ts, lib/data/list.ts	util.go, numeric_semantics.go, list.go
Graphlib graph operations used by D2 and Dagre's default path	graph.go, callback.go, and ordered collection helpers

Verified D2 profile

The release contract is the directed, compound, named-multiedge profile used by D2: graph rankdir, nodesep, edgesep, and ranksep; node IDs, parentage, width, and height; and named edges with width, height, and labelpos. The observable outputs are graph bounds, node and edge-label coordinates, and ordered edge points.

The checked corpus was captured from D2 commit 1a60d69e4df9b9557923e61bf10f9aa3aa5422e1. Across 313 D2 Dagre E2E cases, 270 invoked the adapter, producing 349 calls and 311 unique layout inputs. Official Dagre 3.1.1 returned for 309 inputs, but only 308 results were fully finite. The exact expected-output partition is therefore:

• 308 bit-for-bit official 3.1.1 outputs after D2's JSON bridge normalization;
• three named compatibility outputs: one replaces a successful but non-finite official result, and two replace official errors.

The 311-input corpus and the first three named compatibility cases are derived from D2's MPL-2.0 E2E fixtures and retain D2's copyright and license coverage; see testdata/differential/D2-CORPUS-NOTICE.md and D2-LICENSE.txt. Their expected JSON additionally contains generated layout geometry from the pinned MIT oracle or documented compatibility patch. The synthetic fourth case is generated under Dagro's MIT license. Sources and hashes are recorded in the manifests.

The compatibility cases are:

D2 case	Content-addressed input ID	Official behavior
regression/overlapping-edge-label/dagre	7cfd90e29056db3a1a4d2b45690869ff537734eb5d809ab5f1bb832e59a0bc67	returns non-finite geometry
txtar/theme-overrides/dagre	e052b4c21cba3edb2df9b001d3f64058bf66eb4b30aeec321afa063278915d88	throws during rectangle intersection
stable/us_map/dagre	e2cfd977b7a3bf293fced2080851d9ce8e6bf5425153799b0f3efed58ac27853	throws during rectangle intersection
d2-profile/multiple-reversed-parallel-partners	297220aa20dc2b11460f16bd2c6387f96a4fba40497a7ce71296b45bae600cc4	returns a finite but different layout; synthetic MIT-licensed regression that pins the composition of the two ordering corrections, not a captured D2 fixture

TestLayoutMatchesD2Corpus verifies the partition, every input and expected output hash, finiteness, and exact float64 bits. The pinned JavaScript oracle also checks ordinary fixtures directly and confirms all four documented upstream behaviors rather than silently skipping them.

Compatibility corrections

The reviewable patch testdata/differential/dagre-3.1.1-d2-compat.patch has SHA-256 d510c474e1f291c38c14c276f6bc498dbbd0dc7132e3b9694e31b47650356d19 and applies to the pinned Dagre commit. It makes three changes:

1. The reversed-parallel-edge ordering special case applies only when exactly one dummy represents a reversed edge. Official 3.1.1 can otherwise drop a same-direction dummy from a group of three and propagate non-finite geometry.
2. Every reversed partner for the same forward dummy is retained in encounter order. With correction 1 applied, upstream's single-valued object table can overwrite an earlier opposite-direction partner and leave a valid D2-profile graph without coordinates.
3. A rectangle intersection at the exact center of a zero-width or zero-height node returns the center, and axis-aligned intersections avoid division by zero.

Dagro has one additional public-API safety correction: generated revN names are collision-checked before an internal reversed edge is inserted. This prevents a caller's named multiedge from being overwritten and removes that collision's dependence on global dummy-ID history. Ordinary non-colliding names preserve the official first candidate.

The raw seven-point self-loop route intentionally remains identical to Dagre 3.1.1. Any D2 curve or endpoint-chopping normalization belongs in the D2 adapter and is not hidden in Dagro.

Out of scope

No parity claim is made for dynamic remembered layout state, per-cluster direction, customOrder, ordering constraints, manual rank APIs, rankalign, or other Dagre 3.x surfaces D2 does not use. Graphlib coverage is likewise the D2-used public graph operations plus the operations required internally by the verified layout path, not all of Graphlib 4.0.5.