From the site-book:
The corridors' constant renegotiation of their own boundaries creates a volatility my calculations cannot fully account for. The junctions must be anchored: a fixed point of reference around which the more fluid elements can rotate. Not a physical connection — a conceptual one. A stable, immutable coordinate in the shifting sea of the geometry. I have identified what is needed. It is called the Ariadne Coordinate, and it can be had in the Crawlmarket.
Marginalia, later hand: it could not be had. The Widow Cursorial refused me, at any price. "You think you are building a defense. You are actually building a hunger. And the hunger does not want an anchor; it wants a core. If I give you that link, I am helping you complete the mouth of the beast." I recorded her words as superstition. They were structural analysis, and better than mine.
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Town restoration note. The socket at the junction's center was never filled — the one act of refusal in the whole account, and the reason the Gallery, for all it swallowed, never got a heart. The empty anchor-point is preserved empty. Some links are load-bearing precisely because nobody sells them.