A Space connected to GitHub stays current without polling: every green build of its repository is a webhook delivery, and the delivery imports. A Space that already sits on the built commit is skipped at no cost, which is what makes the arrangement affordable — most deliveries do nothing at all.

That skip is earned by a single field on the sync source, lastSyncCommitSha. And the same field is deliberately held back whenever an import did not fully reconcile: when two-way protection kept server-newer nodes, when a node did not land, or when the import failed outright. Each of those holds exists because advancing past it once lost content. Together they mean something nobody had written down:

A sync source that never reconciles pays a full download and parse of its whole repository on every delivery, for as long as it does not reconcile — and the rate is set by that repository's CI schedule, not by anything about the Space.

On Systemorph/MeshWeaver that schedule is 254 green publish signals in 24 hours (measured 2026-09-10), 87 of them from a probe that runs every fifteen minutes and builds nothing. For the Spaces that reconcile, all 254 cost nothing. For one that does not, all 254 are a clone.

How to tell whether a source is stuck

Open the Space's GitHub Sync settings, or get @{Space}/_GitSync, and compare two of the three clocks:

• lastSyncedAt ≈ lastSyncAttemptAt → the source is reconciling. Nothing to do.
• lastSyncedAt days behind lastSyncAttemptAt, with outcome Imported → it runs, it reports that it imported, and it still has not reconciled. That is the stuck shape.

A frozen lastSyncedAt beside outcome Skipped is not this — that is the sanctioned no-op, and a lastSyncCommitSha a few hours behind the branch tip is normal too, because a delivery imports at the commit the build proved rather than at the tip.

Two live examples measured on 2026-09-10: Essentials last reconciled 2026-08-10 while attempting that same afternoon, 436 commits behind; Deployments on the staff portal last reconciled 2026-08-19 while attempting the same afternoon. Both were reported as Imported every time.

What is now written down

What a Green Build Costs a Synced Space carries the whole model: which workflow runs count as a publish signal, the four reasons a delivery is skipped, what a non-skipped delivery actually transfers (a shallow clone of the entire repository — a configured subdirectory filters what is parsed, never what is downloaded), the three ways the baseline freezes and why each one is correct on its own, what the content-addressed import marker already narrows, and the check above.