The 'virtual node' realized as a centroid force: two allocation-free
O(n) passes per tick (membership resolved once at sim creation;
Float64Array sums). Measured indistinguishable from force-off at 338
nodes (271ms vs 272ms per 400-tick settle).
- createGraphSimulation: SimOptions.clusterPull + linkStrength +
velocityDecay (physics controls plumbing); degree-scaled link
stiffness so linkStrength=1 is exactly d3's default
- settleGraphLayout split into layout-settle.ts (it computes the
Louvain partition for the pull); layout.ts stays browser-barrel-pure
- barrel no longer re-exports clusters.ts: graphology + louvain are
fully out of the client bundle (verified against built chunks)
- replay passes the per-batch partition; CLUSTER_PULL_STRENGTH=0.15
tuned by sweep: cluster spread 63->36 world units, centroid
separation and total span unchanged (no blob merge, no collapse)
One engine owns the equilibrium: the merge settle and (next commit)
the live drag both run createGraphSimulation — d3-force link springs,
1/d charge, weak centroid gravity — so a drag's rest state IS the
server's rest state. The FA2-era anchor mechanism survives as a
post-tick POSITION-SPACE re-blend (retention 0.85): d3's forceLink is
a Hooke spring (strength*(d-L)*alpha), which overpowers any force-space
anchor at long range — the re-blend is alpha-independent and always
wins as the sim anneals (the 675-unit drift bug). Gravity retuned for
d3's 1/d many-body falloff (bootstrap 0.2 / incremental 0.12: cluster
spacing lands ~400 world units, the FA2-era density). Rim orphans seed
(and anchor) at 1.7x the CONNECTED core's mean radius — a max-span-based
rim fed back on itself and ran the layout away to 6000 units. Replay:
338 positions in 1.6s, old-node shift within a batch 4.8 (FA2: 23).
The layout now EVOLVES instead of reshuffling on every extraction. A pure
core module (src/core/layout.ts) warm-starts forceAtlas2 from the positions
ledger (data/graph/positions.json, read-modify-write like sources.json,
updatedAt stamp for future live-physics conflict handling), re-blends every
previously-positioned node toward its anchor each iteration (retention 0.85
- old placements stay recognizable, strong forces still win), seeds new
nodes near their positioned neighbors, and seeds orphans on the rim outside
the core so they read as unconnected knowledge.
- Port/store: GraphStore.readPositions/writePositions; snapshot carries
positions when the ledger exists (optional - fresh graphs unchanged).
- Extraction pipeline settles synchronously after every merge (chat and
notes paths), before usage persist - the next /api/graph fetch already
reflects new nodes.
- View: the ledger IS the layout; the local one-shot FA2 pass survives
only as a fallback when no ledger exists.
- scripts/replay-layout.ts: simulates organic growth by replaying the
current 338-node graph one imported file at a time (real import order,
edges activate when both endpoints exist). Real run: 338 positions in
0.3s, 90-degree-0 orphans collecting at mean r=338 vs connected r=194.
- Also restores the cluster region fills (hull background colors) that
6692b19 had removed on a misreading of "no glow".
Live-verified: fit zoom derives from the ledger bbox, pickAt aligns with
ledger positions at every probe, hover/click/detail-card work, 408/408
tests, typecheck/lint/build green.
Future live physics stays cheap by design: the same pure function is the
merge-time settler and the future client simulator; a pinned node is just
an anchor with full retention.
amosblomqvist