A4 — VM-reconcile damping (negative cache + single-peer catch-up)

[Jurij89]

Summary

• Damps the 60 s VM-reconcile loop: a per-UAL negative cache (5 min base, x2, 6 h cap) that scopes recompute with a cheap bound ASK gate instead of CG-wide counters.
• Replaces all-peers-parallel catch-up with a single peer chosen from preferred/core-first ordering, then round-robin, plus a per-CG fetch cooldown.
• Adds optional tombstoning (DKG_VM_RECONCILE_TOMBSTONE_AFTER_MS, default OFF) to advance the cursor after sustained max-backoff.
• Folds the still-relevant fix(agent): harden chain-driven VM reconcile robustness (audit follow-ups) #934 hardening into A4: transient head-fetch watermark hold, existence-gated core-host recording, tracked core-host persistence on shutdown, deterministic finalization op selection, failed warm-core unpin retry, typed keep-root coverage, and sync checkpoint/since threading tests.

Related

• Part of Sync responder's unbound GRAPH ?g page queries (O(store) per page) + retry/scheduler loops cause the ~9-core oxigraph peg (#1127) and the write-path failures (#1136) — analysis, staged fix plan, and an independent unauthenticated cross-CG read bypass in the same responder #1138 (Track A, PR A4).
• Supersedes fix(agent): harden chain-driven VM reconcile robustness (audit follow-ups) #934 for the still-relevant robustness fixes. The fix(agent): harden chain-driven VM reconcile robustness (audit follow-ups) #934 parser extraction and publication-provenance fallback were intentionally not folded because integration/A3 and Per-KA metadata trim: ~134 → ~50 quads/KA (RFC + Phases 0–3 implementation) #1155 already supersede those paths.
• Targets integration/issue-1138.

Files changed

File	What
packages/agent/src/dkg-agent-swm-host.ts	Negative cache, scoped recompute gate, single-peer round-robin, tombstone, existence-gated core-host recording
packages/agent/src/chain-reconciler.ts	Hold watermark persistence on transient head-fetch failure
packages/agent/src/dkg-agent-base.ts	VM reconcile cache state and tracked core-host recording promises
packages/agent/src/dkg-agent-lifecycle.ts	Track async core-host recording from StorageACK hook
packages/agent/src/dkg-agent.ts	Flush tracked core-host recording promises during stop
packages/agent/src/finalization-handler.ts	Deterministic operation selection for merkle-root match
packages/agent/src/p2p/warm-core-connections.ts	Retry failed warm-core unpins

Plus focused regression tests for A4 and #934 fold-in behavior.

Test plan

• node node_modules/typescript/bin/tsc -p packages/agent/tsconfig.json
• node ../../node_modules/vitest/vitest.mjs run --config vitest.config.ts test/chain-reconciler.test.ts test/core-fills-gap.test.ts test/warm-core-connections.test.ts test/chain-reconcile-e2e.test.ts test/durable-sync-since-threading.test.ts test/sync-checkpoint-key.test.ts --reporter verbose
• node ../../node_modules/vitest/vitest.mjs run --config vitest.config.ts test/sync-on-connect-retry.test.ts test/sync-requester-progress.test.ts --reporter verbose
• $env:NODE_PATH=(Resolve-Path .\node_modules).Path; node ../../node_modules/vitest/vitest.mjs run --config vitest.config.ts test/agent.part-16.test.ts --reporter verbose

---

Targets integration/issue-1138 (not main) so the heavy overlaps on agent lifecycle/base code are resolved once on the integration branch, which is promoted to main in gated waves (see #1138).

[github-actions]

Codex review completed — no issues found.